Printer system with automatic ink ribbon cassette exchange function

Abstract: A printer system includes an ink ribbon end detector for detecting that one of the ink ribbon cassettes (5-5 through 5-8) has been used to the end; an used ink ribbon cassette holding position memory device for storing therein information indicative of holding position of a used ink ribbon cassette (5-5 through 5-8) held on a stocker (5-1) when the ink ribbon cassette end detection means detects that an ink ribbon has been used to the end, and a cassette holding determining device for determining whether or not an ink ribbon cassette (5-5 through 5-8) whose ink ribbon has not been used is set in the stocker (5-1) based on holding information. In the printer system having the described arrangement, an optimal available ink ribbon cassette (5-5 through 5-8) is selected, and in the case of storing plural ink ribbon cassettes (5-5 through 5-8) the same color, a continuous printing operation of a large capacity may be performed without using user's hands.

Description: FIELD OF THE INVENTION The present invention relates to a printer system according to the preamble of claim 1. BACKGROUND OF THE INVENTION According to a conventional color printers, an ink ribbon cassette is divided into a plurality of areas, in a checkered manner (see Fig. 61) or in a stripe manner (see Fig. 62), such as Y (yellow)/M (magenta)/C (cyan)/B (black) so as to be printed while overlapping one another as disclosed in the Japanese unexamined patent publication No. 60-253578/1985 (hereinafter referred to as JP'578). However, such a printer has the problem that the ribbon on whose color is not used is sent without being contributed to the printing when the colors are not uniformly used. In order to solve the problem, the thermal transfer printer disclosed in the JP'578 is arranged such that a plurality of ink ribbon cassettes are prepared so as to be disposed parallel to a moving direction of a carriage, thereby ensuring that the carriage can go and catch a target ink ribbon cassette in accordance with the need. Fig. 63 is an explanatory view illustrating such an arrangement. As illustrated in Fig. 63, a carriage 100 can be moved in the direction parallel to a platen (not illustrated) by a timing belt 107 and a carriage drive motor 108. A stocker 105 can hold four ink ribbon cassettes 101 through 104 in the direction parallel to the platen. Since the carriage 100 holds the ink ribbon cassette 103 as illustrated in Fig. 63, the printing can be carried out by a printing head 109 with the use of the ink ribbon cassette 103. When carrying out the printing with the use of another ink ribbon cassette such as an ink ribbon cassette 103, the ink ribbon cassettes 101 may be acquired by the carriage 100 after the ink ribbon cassette 103 is returned to a vacant position of the stocker 105. The following methods are for delivering an ink ribbon cassette between the carriage 100 and the stocker 105: a method wherein the carriage moves and gets the necessary ink ribbon cassette without the movement of the stocker; and a method wherein the stocker itself moves and places the ink ribbon cassette on the carriage. Here it is assumed that the colors of the respective ink ribbon cassettes 101 through 104 are the same. In such a case, when the ink ribbon cassette 101 is ended, the ink ribbon cassette 102 is substituted therefor. When the ink ribbon cassette 102 is ended, the ink ribbon cassette 103 is substituted therefor. Thus, the consecutive printing can be carried out. According to the JP'578, a method wherein four ink ribbon cassettes are stacked on a carriage is proposed. Fig. 64 is an explanatory view illustrating the method proposed in the JP'578, and shows that the upper most ink ribbon cassette 101 among the four stacked ink ribbon cassettes is in a state where the printing operation can be carried out. In such a state, in order to change the ink ribbon cassette with another one for use in the printing operation, it is required that (1) a motor (not illustrated) for moving up and down the ink ribbon cassette is rotated, (2) the legs of a cassette cradle are pushed up, and (3) the motor from moving up and down the ink ribbon cassette is stopped when the next ink ribbon cassette is disposed in the position of the printing head 109. In the case where the printing is carried out by moving the ink ribbon cassettes group in the moving direction of the printing head, i.e., in the vertical direction with respect to the shaft direction of the platen, when the current ink ribbon is consumed, the changing of the ink ribbon cassettes are automatically carried out from the fourth stacked ink ribbon cassette to the third stacked ink ribbon cassette, from the third to the second, and from the second to the first. Thus, the consecutive printing can be carried out. According to the Japanese unexamined patent publication No. 62-227781/1987 (hereinafter referred to as JP'781), the consecutive printing by the ink ribbon can be carried out with the use of a thermal transfer serial printer in which an ink ribbon cassette containing two ink ribbons is provided. Fig. 65 is a front view illustrating the state where the lower side ink ribbon (159b) of the two ink ribbons 159a and 159b which are contained by the ink ribbon cassette 158 is used. Fig. 66 is a front view illustrating the state where the upper side ink ribbon (159a) of the two ink ribbon s 159a and 159b is used. In Figures 65 and 66, supporters 156a and 156b are (1) fixed to a holder 155 for holding the ink ribbon cassette 158, (2) are fitted to respective guides 153a and 153b which are fixed to a carrier frame 151, and (3) are slidable in the up-and-down direction by a driving mechanism 155a (a solenoid 152, an armature 152a, and a spring 152b). In Fig. 65, when one line printing with the ink ribbon 159b is finished, the printing operation is suspended so that the holder 155 is pushed down so as to change the state into that of Fig. 66. Namely, the state is realized where the ink ribbon 159a and the printing head 154 can neighbor with each other. Then, the printing operation restarts while the ink ribbon 159a is fed by a ribbon motor 157. When it is detected that the ink ribbon 159a became in a ribbon end state during repeatedly carrying out the bidirectional printing in accordance with the foregoing operations, the printing operation is suspended. In such a case, the printing for the remaining characters is continuously carried out while the ink ribbon cassette 158 is lifted up to the position of Fig. 65 and the ink ribbon 159b is driven. The following is well known as the printers having no stocker: a thermal printer disclosed in the Japanese unexamined patent publication No. 61-112666/1986 (hereinafter referred to as JP'666); a thermal transfer recording apparatus disclosed in the Japanese unexamined patent publication No. 3-187777/1991 (hereinafter referred to as JP'777); and a thermal printer disclosed in the Japanese unexamined patent publication No. 5-169783/1993 (hereinafter referred to as JP'783). According to such a printer, the printing is carried out with respect to a plain paper with the use of an ink ribbon cassette, in addition thereto the printing may be carried out with respect to a thermosensible paper which colors up on receipt of heat. The printer has the problem that the ink ribbon cassette should be taken out for each printing with respect to the thermosensible paper. In order to solve the problem, the thermal printer disclosed in the JP'666 proposes the arrangement wherein a carriage is provided with the moving mechanism for moving the ink ribbon cassette from a thermal head and wherein the ink ribbon cassette is taken out from the thermal head during the mode in which the printing is carried out with respect to the thermosensible paper which does not necessitate the use of the ink ribbon cassette. Figs. 67(a) and 67(b) are explanatory views illustrating such an arrangement, Fig. 67(a) illustrates the state in which the printing is carried out with respect to the plain paper while Fig. 67(b) illustrates the state in which the printing is carried out with respect to the thermosensible paper. A carriage 110 can be moved by a timing belt (not illustrated) and a carriage drive motor (not illustrated) in a direction vertical to a moving direction of a recording paper 111 as illustrated in Figures 67(a) and 67(b). The carriage 110 is provided with (1) an ink ribbon cassette holder mechanism 113 having an ink ribbon cassette winding mechanism 112 and (2) a printing head 114. With the arrangement, the printing is carried out by the printing head 114 with an ink ribbon cassette 115 being held by the carriage 110. In contrast, when the printing is carried out with respect to a thermosensible paper 119 without the ink ribbon cassette 115, the ink ribbon cassette holder mechanism 113 is pushed up by a cam plate 116, which is actuated by a motor 118 and a gear 117 in the carriage, so that the printing is carried out while the ink ribbon cassette 115 is taken away from the printing head 114. Figs. 68(a) and 68(b) are views illustrating the arrangement disclosed in the JP'783, Fig. 68(a) illustrates the state in which the printing is carried out with respect to the plain paper while Fig. 68(b) illustrates the state in which the printing is carried out with respect to the thermosensible paper. In the thermal printer disclosed in the JP'783, like the foregoing case, a carriage 120 is provided with an ink ribbon cassette plate 122 for holding an ink ribbon cassette 121, the carriage 120 being moved by a timing belt (not illustrated) and a drive motor (not illustrated) in a direction vertical to a moving direction of printing paper (not illustrated). The carriage 120 is connected with the ink ribbon cassette plate 122 by a moving arm 123 so that the ink ribbon cassette plate 122 can be parallelly moved with respect to the carriage 120. With the arrangement, in the mode in which the printing is carried out with respect to the thermosensible paper without the ink ribbon cassette 121, a cam 124 pushes up the ink ribbon cassette plate 122 so that a printing head 125 directly comes into contact with printing paper (not illustrated), thereby ensuring that the printing is carried out with respect to the thermosensible paper without the user's removing operation of the ink ribbon cassette 121. The thermal transfer recording apparatus disclosed in the JP'777 proposes the structure in which (1) a carriage holds a plurality of ink ribbon cassettes and (2) a mechanism is prepared for avoiding of the erroneous insertion of the ink ribbon cassette, thereby ensuring that the plurality of ink ribbon cassettes are simultaneously used for the multiple color printing. Fig. 69 is an explanatory view illustrating such a thermal transfer recording apparatus. There is provided, on a carriage 127, with a cassette plate 128 which can hold a plurality of ink ribbon cassettes that are elevated by an elevator 126, the carriage 127 being moved by a timing belt (not illustrated) and a drive motor (not illustrated) in a direction vertical to a moving direction of printing paper (not illustrated). When the color printing is carried out by the thermal transfer recording apparatus, a yellow ink ribbon cassette 129c, a magenta ink ribbon cassette 129b, and a cyan ink ribbon cassette 129a are stacked in this order on the cassette plate of the carriage 127 (see Fig. 70) so that (1) the printing is carried out in yellow color by the yellow ink ribbon cassette 129c while keeping the cassette plate 128 lowered, then (2) the printing is carried out in magenta color by the magenta ink ribbon cassette 129b while the elevator 126 keeps the cassette plate 128 raised by one stage, and thereafter (3) the printing is carried out in cyan color by the cyan ink ribbon cassette 129a while the elevator 126 keeps the cassette plate 128 further raised by another one stage. The three different color ink ribbon cassettes 129a through 129c have detection elements 130a through 130c for identifying respective ink ribbon colors (see Fig. 71). Detection switches 131a through 131c for detecting the detection elements 130a through 130c respectively are provided in the cassette plate 128 (see Figures 69 and 70). As illustrated in Fig. 69, in the cassette plate 128, the detection switches 131a through 131c are disposed so as to come into contact with the detection elements 130a through 130c of the respective ink ribbon cassettes 129a through 129c when the ink ribbon cassettes 129a through 129c are attached to the cassette plate 128. When the ink ribbon cassettes 129a through 129c are attached to the cassette plate 128, the detection switches 131a through 131c detect the detection elements 130a through 130c of the respective ink ribbon cassettes 129a through 129c, thereby judging whether or not the respective ink ribbon cassettes 129a through 129c are appropriately attached to the cassette plate 128. The detail operations of the thermal printer in the JP'666, the thermal transfer recording apparatus in the JP'777, and the thermal printer in the JP'783 are disclosed in the respective unexamined patent publications, so such explanations are omitted here. In Figs 72(a) and 72(b), a printing paper feed roller feeds a printing paper 111 in an arrow direction. When the printing paper 111 is inserted, the output of a sensor 113 for detecting whether or not the printing paper exists becomes the on state. The following methods are for delivering an ink ribbon cassette between the carriage 100 and the stocker 105: a method wherein the carriage moves and gets the necessary ink ribbon cassette without the movement of the stocker; and a method wherein the stocker itself moves and places the ink ribbon cassette on the carriage. Figures 72(a) and 72(b) illustrate the latter method. Fig. 72(a) illustrates the state where the stocker is moved up, while Fig. 72(b) illustrates the state where the stocker is moved down so that the ink ribbon cassette is held by the carriage. According to the Japanese unexamined patent publication No. 2-258276/1990 (hereinafter referred to as JP'276), in order to smoothly feed the printing paper, the carriage is moved to the center of the printing paper so as to press the printing paper during feeding of the printing paper, so that the jam of the printing paper can be avoided. Figures 73 through 75 are explanatory views illustrating the technique of JP'276. In Fig. 73, the feed system of the printer is composed of a printing head 201, a platen 202 facing the printing head 201, a ribbon guide 206 disposed between the printing head 201 and the platen 202, a carriage (carrier) 207, movable in the right and left directions, having the printing head 201 and the ribbon guide 206, a tractor 204 for feeding a printing paper 203, and a cutter 205 for cutting away the printing paper. The tractor 204 is driven to rotate by a stepping motor 209 through a driving shaft 208. The carriage 207 is horizontally moved by a stepping motor 211 through a timing belt 210. There is provided a detection sensor 212, for determining the feed position of the printing paper, on the feed path connecting the printing head 201 and the tractor 204. Fig. 74 is a view illustrating the position of the carriage 207 when the printing paper 203 is fed in the discharge direction. Fig. 75 is an enlarged view illustrating the printing paper feed path up to the cutter after the printing. A predetermined amount of the printing paper is fed based on the fact that (1) the printing paper 203 is set to the tractor 204, (2) the stepping motor 209 is driven upon pressing a switch on an operation panel so as to feed the printing paper 203, and (3) the detection sensor 212 detects the upper end portion of the printing paper. Note that the carriage 207 is driven by the stepping motor 211 so as to move to the center of the printing paper upon pressing the switch on the operation panel (see Fig. 74), thereby causing that the printing paper 203 is pressed by the ribbon guide 206. Thus, the printing paper 203 is fed while being fallen in a direction reverse to the direction in which the printing paper 203 winds around the platen 202 (the printing paper feed path), and the upper end portion of the printing paper is caught by a guide lower end 205'' of the cutter 205, thereby avoiding the printing paper jam. In a conventional printer which can not change the ink ribbon cassette while holding a plurality of ink ribbon cassettes, when a ribbon end is detected during printing, it is required that (1) the printing is suspended so that the user takes away the ink ribbon cassette from the carriage and attaches the new ink ribbon cassette on the carriage, and thereafter (2) the user restarts the printing. JP'578 does not disclose how to control the continuous printing when a plurality of same color ribbons are set. However, since one ink ribbon cassette can be automatically changed with another ink ribbon cassette, the method, where in the printing is carried out while changing the ink ribbon cassettes in order when each ribbon end is detected during printing, may be proposed. However, such a method presents the problem that it is likely that the printing is carried out while the ink ribbon cassette which is already ended is attached to the carriage again, since the holding positions of the respective ink ribbon cassettes which are already ended are not stored. In contrast, when the holding positions of the ink ribbon cassettes which are already ended are stored, the following problem arises. More specifically, even though the user changes the ink ribbon cassette which is already ended with a new one, the new ink ribbon cassette will never be used since it is not detected on the printer side whether or not the changing of the ink ribbon cassette has been carried out. Moreover, since the control wherein the ink ribbon cassette having least remaining amount has priority over other ink ribbon cassettes to be used is not carried out, it is likely that a plurality of ink ribbon cassettes which can still be used are presented. According to the continuous printing method of the ribbons disclosed in JP'781, one ink ribbon cassette contains two ink ribbons and when one ink ribbon is ended, another ink ribbon is substituted therefor. However, such a method presents the problem that the user can not know whether or not only one ink ribbon has been ended when the first ink ribbon was ended. Thus, since the printing can not be carried out when the second ink ribbon is ended, at this time the user must simultaneously change two ink ribbon cassettes with new ones. Even if the user knows that the first ink ribbon cassette is ended and changes only the first one with a new one, the printer can not know the changing of the first ink ribbon cassette. Therefore, the printer continues the printing with the use of only the second ink ribbon cassette though the first ink ribbon cassette has been changed with a new one. Accordingly, though such a printing method carries out the bidirectional printing with the alternate use of the first and second ink ribbons, the continuous printing can not be carried out while changing the ink ribbon each time each ink ribbon is ended. In the arrangement where the stocker is provided which stores plural ink ribbon cassettes in a direction parallel to the moving direction of the carriage, and the ink ribbon cassette is exchanged between the carriage and the stocker, the following problems are presented. In order to exchange the ink ribbon cassette between the carriage and the stocker smoothly and speedily, it is required to place the carriage and the stocker so as to face one another and to set the distance between them as small as possible. Therefore, the space between the carriage and the stocker wherein the ink ribbon cassette is set becomes small, and it is not easy to insert the user's hand, thereby presenting the problem of inconvenience in exchanging the cassette. For this reason, it may be arranged such that the user exchanges the ink ribbon cassette by adopting the stocker which is rotatable or detachable, i.e., by opening the stocker. However, if the carriage is activated by mistake when the stocker is opened, even if the exchange is not performed properly, the printing may be started using the wrong ink ribbon cassette without notice. Moreover, in the case of placing the ink ribbon cassette on the carriage by moving the stocker in the direction of the carriage, since the entire height of the printer is low, by setting such that the printer is set in this state except during the printing operation, the printer can be miniaturized. However, in this state, since the stocker and the carriage are in tight contact with one another through the ink ribbon cassette, it is not possible for the user to exchange the ink ribbon cassette. Furthermore, when the ink ribbon has been used to the end in the middle of the printing operation, and the ink ribbon cassette of the same kind (color) is not stored in the stocker, the new ink ribbon cassette is set on the carriage, and the printing operation must be restarted. In the described printer, it is difficult to set and take out the ink ribbon cassette on and from the carriage as being disturbed by the mechanical section of the stocker and the carriage. In the case of the printer which is not provided with the detection means for detecting the kind (color) of the ink ribbon cassette for reducing the cost, etc., normally, the color of the ink ribbon cassette to be mounted to the position of the stocker is set beforehand, for example, black, yellow, magenta, cyan, etc. from the left end, so as to store the color of the ink ribbon each time. However, when the user sets the ink ribbon cassette not on the stocker but directly on the carriage, since the printer does not know the set ink ribbon cassette is in what color, a printing operation may not be performed in correct color. The thermal transfer printer disclosed in the JP'578 is an automatic changer printer in which the ink on the ribbon of the ink ribbon cassette is transferred to the printing paper by heating a plurality of small heating elements disposed on the printing head while the printing head comes into contact with the ink ribbon. However, since there is no sensor for detecting whether or not the ink ribbon cassette is attached to the carriage, it can not be detected whether or not the ink ribbon cassette is attached onto the carriage. Thus, in the case where the printing is carried out with respect to a thermosensible paper which colors upon receipt of heat without the ink ribbon cassette, the user has to confirm whether the ink ribbon cassette is not attached to the carriage for each printing so that the printing is not carried out while the ink ribbon cassette is attached to the carriage. When the user finds that the ink ribbon cassette is attached to the carriage, the user must take out the ink ribbon cassette from the carriage. Note that no description concerning the printing with respect to the thermosensible paper is disclosed in the the JP'578. Moreover, in the case where the ink ribbon cassette is automatically moved to the carriage for each printing from the stocker which holds the ink ribbon cassettes, the ribbon which is to be moved to the carriage should be taken out from the stocker beforehand prior to each printing. Namely, it is required to confirm for each thermosensible paper printing whether or not the ink ribbon cassette is attached to the carriage so that the printing is not carried out with the ink ribbon cassette, thereby presenting the problem that the printing is not effectively carried out. According to the thermal printer of the JP'666 and the thermal printer disclosed in the JP'783, the user can carry out, without taking out the ink ribbon cassette at the user's end, (1) the printing with respect to the plain paper with the ink ribbon cassette and (2) the printing with respect to the thermosensible paper without the ink ribbon cassette. However, it is not considered to carry out the multiple color printing with the use of a plurality of ink ribbons. Accordingly, the user must change the ink ribbon cassette in accordance with the color to be printed for each multiple color printing. In especial, three color ink ribbon cassettes, i.e., the yellow, magenta and cyan ink ribbon cassettes, are ordinarily used for the color printing. So, it is frequently required to change the ink ribbon, thereby presenting the problem that the color printing can not effectively carried out. In order to carry out only the color printing, the complicated structure is separately required, thereby presenting another problem. According to the thermal transfer recording apparatus disclosed in the JP'777, with the use of a plurality of ink ribbon cassettes, the user can effectively carry out the multiple color printing without changing the ink ribbon cassette. The thermal transfer recording apparatus is arranged so that the ink ribbon cassettes are stacked on the carriage. When the printing is carried out with respect to thee thermosensible paper, another sliding corresponding to one ink ribbon cassette is required so that the printing head does not face the ink ribbon of the ink ribbon cassette thereby realizing the printing with respect to the thermosensible paper. So, when using three color ink ribbons such as yellow, magenta and cyan ink ribbons, the space for four ink ribbon cassettes should be totally prepared on the carriage for the color printing based on the fact that the space for the three ink ribbon cassettes and the space for the sliding during the printing with respect to the thermosensible paper should be prepared, thereby requiring the great space and thereby resulting in that the printer becomes bulky. According to the thermal transfer printer disclosed in the JP'578, there is no sensor provided for detecting whether or not the ink ribbon cassettes are attached to the stocker, i.e., for detecting the ink ribbon cassette holding states of the respective carriage and stocker. This causes to present the problem that no errors can be detected such as (1) the error that the changing operation is not appropriately carried out due to some error that the automatic changer fails to move the ink ribbon cassette from the carriage to the stocker for example or (2) the error that the ink ribbon cassette is detached in response to the externally applied shocks during printing. When the error is not detected, the stresses are concentrated on the element whose strength is weaker, thereby causing to present the problem that the printer becomes out of order or the elements are damaged. The thermal transfer printer disclosed in the JP'578 is a color printer that can carry out the multiple color printing by automatically changing the three color ink ribbon cassettes, for example, Y (yellow)/M (magenta)/C (cyan) ink ribbon cassettes during the printing, although only a single ink ribbon cassette can be attached to the carriage at a time. In general, when carrying out the color printing, it is required that (1) the data to be printed are divided into respective Y (yellow)/M (magenta)/C (cyan) components and (2) the Y component data are printed by the Y color ink ribbon cassette, the M component data are printed by the M color ink ribbon cassette, and the C component data are printed by the C color ink ribbon cassette. Accordingly, when the ink ribbon cassettes are not attached to respective appropriate positions in the stocker, the color printing can not appropriately be carried out. The thermal transfer printer disclosed in the JP'578 has no sensor for detecting whether or not the ink ribbon cassettes have been attached to the stocker. So, the user can not judge whether or not each ink ribbon cassette has been appropriately attached to the stocker for each selected printing mode, thereby presenting the problem that the appropriate printing may not be carried out. The thermal transfer recording apparatus disclosed in the JP'777 identifies each one of the ink ribbon cassettes stacked on the carriage based on the fact that the detection switches, provided in the cassette plate for identifying the types of the respective ink ribbon cassettes, detect the respective detection elements attached to the respective ink ribbon cassettes so that the respective ink ribbon cassettes have been appropriately attached. However, since the ink ribbon cassettes are stacked on the carriage, the following problems (a) and (b) arise: (a) (1) the thickness of the carriage including the thickness of the cassette plate becomes thicker in proportion to the attachable number of the ink ribbon cassettes and (2) the entire thickness of the printer becomes so thick because the space on the upper side of the carriage for the sliding width by which the cassette plate elevates is further required; and (b) it is only judged whether or not the ink ribbon cassette is the one which should be held in its ink ribbon cassette holding position because only a single detection switch is provided in each ink ribbon cassette holding position in the cassette plate. According to the ink ribbon cassette automatic changer printer disclosed in JP'578, the ink ribbon cassette is delivered between the stocker and the carriage based on the fact that the stocker is moved up and down by the changer, thereby enabling to attach and detach the ink ribbon cassette. Accordingly, if the carriage is tried to be moved when (1) the stocker has been moved down by the changer or (2) the stocker has been down due to some reasons, the carriage can not be moved because the carriage collides with the stocker, thereby causing to excessively burden the carriage drive motor. So, to keep moving the carriage under such a condition causes the carriage drive motor to be heated up, thereby presenting the reasons of some faults and accidents. According to the ink ribbon cassette automatic changer printer disclosed in JP'578, the ink ribbon cassette is delivered between the stocker and the carriage based on the fact that the stocker is moved up and down by the changer, thereby enabling to attach and detach the ink ribbon cassette. Accordingly, in the case where the carriage is forcedly moved by the user when the stocker has been moved up by the changer, if the changer tries to move down the stocker, the carriage collides with the stocker, thereby causing to excessively burden the changer. So, if the changer keeps moving down the stocker under such a condition, it causes that the carriage drive motor is heated up, thereby presenting the reasons of some faults and accidents. Alternatively, if the changer tries to move up the stocker when something is placed on the stocker, such a movement excessively burdens the changer, thereby presenting the problem similar to the foregoing case. According to the ink ribbon cassette automatic change printer disclosed in JP'578, the ink ribbon cassette is delivered between the stocker and the carriage based on the fact that the stocker is moved up and down by the changer, thereby enabling to attach and detach the ink ribbon cassette. So, if the user tries to set the printing paper when the stocker has been moved up by the changer, such operation presents the problem that the printing paper is caught by the lower end portion of the stocker (see Fig. 72(a)). JP'276 discloses a technical method wherein the carriage is controlled so as to move to the center of the printing paper, thereby avoiding the paper jam. However, in the foregoing ink ribbon cassette automatic changer printer having the stocker, when the carriage is merely moved to the center of the printing paper, both ends of the printing paper are caught by the lower end portion of the stocker, thereby presenting the problem that it is not possible to smoothly feed the printing paper. Therefore, in order to supply the printing paper to the foregoing ink ribbon cassette automatic changer printer having the stocker, it is required that the stocker is kept be down so that the printing paper is not caught by the lower end portion of the stocker. In other words, when the stocker is kept be down, the printing paper is not caught by the lower end portion of the stocker. Thus, the printing paper is guided by the front surface portion of the stocker so as to be fed (see Fig. 72(b)). In the case where the user supplies the printing paper to the printer when the stocker is kept be up, it is required for the user to carry out the operation for moving down the stocker prior to supplying the printing paper, thereby requesting the user to have troublesome things. According to the ink ribbon cassette automatic changer printer disclosed in JP'578, the ink ribbon cassette is delivered between the stocker and the carriage based on the fact that the stocker is moved up and down by the changer, thereby enabling to attach and detach the ink ribbon cassette. Therefore, in the case where the changer moves up from the down state after setting the printing paper, when the stocker is moved up while the ink ribbon cassette is held by the carriage and the ink ribbon cassette which is first used after starting to print is different from that held by the carriage, it is required that the ink ribbon cassette of the carriage is once returned to the stocker and the ink ribbon cassette which is first used for the printing is attached to the carriage. Thus, the problem arises that another time is required for returning the ink ribbon cassette to the stocker, thereby requiring longer time for starting the printing operation. In contrast, in the case where the stocker is moved up from the down state by the changer after setting the printing paper, when the stocker is moved up after removing the ink ribbon cassette from the carriage and the ink ribbon cassette which is first used after starting to print is coincident with that which has been originally held by the carriage, it is required that the same ink ribbon cassette must be attached to the carriage again, thereby causing dead time and dead operation in the entire printing operation. According to the ink ribbon cassette automatic changer printer disclosed in JP'578, the ink ribbon cassette is delivered between the stocker and the carriage based on the fact that the stocker is moved up and down by the changer, thereby enabling to attach and detach the ink ribbon cassette. Therefore, it is judged, when the carriage is not provided with the ink ribbon cassette type detection device, what type of the ink ribbon cassette is attached to the carriage by judging that the ink ribbon cassette was removed from what position of the stocker. The types (colors) of the respective ink ribbon cassettes which are held by the stocker are predetermined, i.e., for example, the colors of the respective ink ribbon cassettes of the stocker are B (black), Y (yellow), M (magenta) and C (cyan) respectively from the left end to the right end in this order. So, when the ink ribbon cassette is attached to the carriage during staying of the carriage in the left end of the stocker, it can be identified that the color of thus attached ink ribbon cassette is black. However, generally, in the conventional printers, a sensor is provided which turns ON when the carriage moves to the left end of the stocker. The position of the carriage is identified in accordance with the moved distance of the carriage from the position in which the sensor turns ON. Thus, the position of the carriage can not be identified before carrying out the initialization of the printer. The initialization is carried out, for example, just after turning on the power source. When the initialization of the printer is carried out, for example, the carriage is moved to the position in which the sensor turns ON. Accordingly, at that time, the type (color) of the ink ribbon cassette which has been attached to the carriage by the changer can not be identified. Even in the case where the ink ribbon cassette has already been attached to the carriage at turning on the power source, the type (color) of the ink ribbon cassette can not be identified. Finally, document US-A-5,267,802 discloses a printer having a carriage for holding a cassette including a thermal print head so as to be movable, a turret for storing a plurality of cassettes so as to be detachable therefrom, and a moving device for moving the cassette on the carriage to a right end so as to deliver the cassette between the carriage and the turret. When the ink ribbon cassette is moved from the carriage to the position where the stocker is mounted, the ink ribbon cassette is not mounted to the position before being mounted. However, irrespectively of the fact that the ink ribbon cassette is held in the stocker, the ink ribbon cassette is moved to the stocker, and the ink ribbon cassette is moved to the position where the ink ribbon cassette of the stocker is held, which may cause a damage of the stocker. As a result, even if the carriage has already held the ink ribbon cassette which is first used at the starting of the printing, it is required that (1) the ink ribbon cassette is once returned to the stocker, (2) the position of the carriage is identified, and thereafter (3) the ink ribbon cassette is again held by the carriage, thereby presenting the problem that the printer must do such vain operations. SUMMARY OF THE INVENTION The present invention is achieved in finding a way to solve the above-mentioned problems. Accordingly, a printer system with an automatic ink ribbon exchange function of the present invention permits the following object to be achieved. An object of the present invention is to provide a printer system with an automatic ink ribbon cassette exchange function in which (1) the removing operation of an ink ribbon cassette during printing to thermo-sensible paper which does not necessitate the ink ribbon cassette is included so as to reduce the printing steps and so as to effectively carry out the printing with high speed and (2) the thickness of the printer is reduced and the printing is effectively carried out with high speed. In order to achieve the above object, the present invention provides a printer as specified in claim 1. Preferred embodiments of the invention are described in the sub claims. For a fuller understanding of the nature and advantages of the invention, reference should be made to the ensuing detailed description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view corresponding to a claim of a printer system in accordance with the present invention. Fig. 2 is a view corresponding to a claim of another printer system in accordance with the present invention. Fig. 3 is a view corresponding to a claim of a still another printer system in accordance with the present invention. Fig. 4 is a view corresponding to a claim of a yet another printer system in accordance with the present invention. Fig. 5 is a block diagram illustrating the basic structure of an ink ribbon cassette automatic changer printer. Fig. 6 is an explanatory view illustrating how ink ribbon cassettes are held by a stocker. Figures 7(a) and 7(b) are explanatory views illustrating a holding state of the stocker. Figures 8(a) and 8(b) are explanatory views illustrating how the stocker is opened. Figures 9(a) through 9(d) are explanatory views illustrating a changer upper end sensor and a changer lower end sensor. Fig. 10 is an explanatory view illustrating an ink ribbon end sensor. Fig. 11 is an entire view illustrating an ink ribbon cassette automatic changer printer in accordance with one embodiment of the present invention. Fig. 12 is an entire view illustrating another ink ribbon cassette automatic changer printer in accordance with one embodiment of the present invention. Fig. 13 is an entire view illustrating a still another ink ribbon cassette automatic changer printer in accordance with one embodiment of the present invention. Fig. 14 is an entire view illustrating a still another ink ribbon cassette automatic changer printer wherein the stocker is opened. Figures 15(a) through 15(d) are explanatory views illustrating how an ink ribbon cassette is delivered between the stocker and a carriage. Fig. 16 is a flow chart for controlling of the changing of the ink ribbon cassette during the continuous printing. Fig. 17 is a flow chart for a case where an instruction for stopping the printing is entered during the continuous printing. Fig. 18 is a view illustrating one example wherein the user inputs the order in which the remaining amount of the ink ribbon cassette becomes less. Fig. 19 is an explanatory view showing information of the remaining amounts of the respective ink ribbons which are stored in a memory device. Fig. 20 is an explanatory view illustrating information of the holding positions of the respective ended ink ribbon cassettes which are stored in a memory device. Fig. 21 is a view illustrating one example of displayed screen for informing the user of the holding positions of the respective ended ink ribbon cassettes. Fig. 22 is a flow chart how the stocker is controlled so as to be moved down. Fig. 23 is a flow chart how the ink ribbon cassette is controlled so as to be changed. Fig. 24 is a flow chart showing the detail of the step S71 of Fig. 23. Fig. 25 is an explanatory view illustrating color information of the respective ink ribbon cassettes which are stored in the memory device of the holding positions. Fig. 26 is a flow chart showing the detail of the step S71 of Fig. 23. Fig. 27 is a view illustrating one example of displayed screen for requesting the user to input the colors of the ink ribbon cassette. Fig. 28 is an entire view illustrating an ink ribbon cassette automatic changer printer wherein a stocker is provided with a stocker cassette type identification sensor. Figures 29(a) through 29(d) are explanatory views illustrating the identification holes for identifying the types of the respective ink ribbon cassettes. Fig. 30 is an explanatory view showing the relation between the positions of the respective identification holes and the ribbon types of the respective ink ribbon cassettes. Fig. 31 is an explanatory view showing a case where it is judged on the carriage side whether or not the ink ribbon cassettes exist with the use of the stocker having no stocker cassette holding sensor. Fig. 32 is an explanatory view showing a case where it is judged on the carriage side whether or not the ink ribbon cassettes exist and the kind of the ink ribbon cassette with the use of the stocker having no stocker cassette type identification sensor. Figures 33(a) through 33(d) are explanatory views illustrating the identification holes for identifying the types of the respective ink ribbon cassettes. Fig. 34 is an explanatory view showing the relation between the positions of the respective identification holes and the ribbon types of the respective ink ribbon cassettes. Fig. 35 is a flow chart showing what procedures are made for printing to the thermosensible paper. Fig. 36 is a flow chart showing what procedures are made for checking the holding states of the respective ink ribbon cassettes of the stocker before and after the movement of changer. Fig. 37 is a flow chart showing what procedures are made for checking the holding states of the respective ink ribbon cassettes of the stocker in a predetermined time interval during the printing. Fig. 38 is a flow chart showing what procedures are made for checking the holding states of the respective ink ribbon cassettes of the stocker in a predetermined time interval during the printing. Fig. 39 is a flow chart showing what procedures are made for checking the holding states of the respective ink ribbon cassettes of the stocker prior to the printing. Fig. 40 is a flow chart showing what procedures are made for checking the holding states of the respective ink ribbon cassettes of the stocker prior to the printing so as to appropriately carry out the printing. Fig. 41 is an explanatory view showing one example of the holding states of the respective ink ribbon cassettes. Fig. 42 is another explanatory view showing one example of the holding states of the respective ink ribbon cassettes. Fig. 43 is an explanatory view showing one example of the ink ribbon cassettes required for the printing mode stored in the memory device. Fig. 44 is an explanatory view showing one display example of the suitable holding state data of the respective ink ribbon cassettes stored in the memory device. Fig. 45 is an explanatory view showing one display example of the screen for inputting the types of the respective ink ribbon cassettes of the stocker. Fig. 46 is an explanatory view showing one storing example of the holding states of the ribbon types of the respective ink ribbon cassettes. Fig. 47 is a flow chart showing what procedures are made for judging on the carriage side whether or not the ink ribbon cassettes exist with the use of the stocker having no stocker cassette holding sensor. Fig. 48 is a flow chart showing what procedures are made for judging on the carriage side whether or not the ink ribbon cassettes exist and the type of the ink ribbon cassette with the use of the stocker having no stocker cassette type identification sensor. Fig. 49 is an explanatory view showing the states where the existence and non-existence of each ink ribbon cassette of the stocker is stored in the memory device. Fig. 50 is an explanatory view showing one storing example of the holding states of the ribbon types of the respective ink ribbon cassettes. Fig. 51 is an explanatory view showing a table for judging the up and down positions of the stocker according to the on and off states of the respective changer upper end and lower end sensors. Figures 52(a) and 52(b) are side views of an ink ribbon cassette automatic changer printer of an embodiment. Fig. 53 is a flow chart showing how the changer prohibits the movement of the carriage when the changer is not in the carriage movable state. Fig. 54 is a flow chart showing what procedures are made for prohibiting the movement of the changer when the changer does not become a target state. Fig. 55 is a flow chart showing what procedures are made for automatically moving the changer from the carriage movable state into a ribbon changing state after the printing operation. Fig. 56 is a flow chart showing what procedures are made for automatically moving the changer from the carriage movable state into the ribbon changing state when turning on the power source. Fig. 57 is a flow chart showing what procedures are made for prohibiting the moving-up of the stocker until the printing paper is supplied. Fig. 58 is a flow chart showing (1) the procedures of whether or not the stocker is moved up while holding the ink ribbon cassette when starting the printing and (2) the procedures for identifying the type of the ink ribbon cassette on the carriage in accordance with the ink ribbon cassette holding states of the stocker when the type of the ink ribbon cassette on the carriage can not be identified. Fig. 59 is an explanatory view showing the storing state wherein the types of the respective ink ribbon cassettes which are held by the stocker. Figures 60(a) and 60(b) are explanatory views showing the storing state wherein the respective ink ribbon cassettes holding states of the stocker. Fig. 61 is an explanatory view illustrating one example of a conventional color ink ribbon. Fig. 62 is another explanatory view illustrating one example of a conventional color ink ribbon. Fig. 63 is an explanatory view illustrating a conventional ink ribbon cassette automatic changer printer. Fig. 64 is a plane view illustrating a conventional printer. Fig. 65 is a front view illustrating a conventional printer of JP'781 in which especially the lower side ribbon is used. Fig. 66 is a front view illustrating a conventional printer of JP'781 in which especially the upper side ribbon is used. Figures 67(a) and 67(b) are explanatory views illustrating the states of the ink ribbon cassette of the case where the printing is carried out with respect to the plain paper and thermosensible paper by a conventional ink ribbon cassette automatic changer printer. Figures 68(a) and 68(b) are another explanatory views illustrating the states of the ink ribbon cassette of the case where the printing is carried out with respect to the plain paper and thermosensible paper by a conventional ink ribbon cassette automatic changer printer. Fig. 69 is an explanatory view illustrating a carriage of a conventional multiple color thermal transfer recording apparatus in which a plurality of ink ribbon cassettes are simultaneously used. Fig. 70 is an explanatory view illustrating the relation between the detection switches of a conventional multiple color thermal transfer recording apparatus in which a plurality of ink ribbon cassettes are simultaneously used and the ink ribbon cassettes. Fig. 71 is an explanatory view illustrating the types of the ink ribbon cassettes used in a conventional multiple color thermal transfer recording apparatus in which a plurality of ink ribbon cassettes are simultaneously used. Figures 72(a) and 72(b) are side views illustrating a conventional ink ribbon cassette automatic changer printer. Fig. 73 is an explanatory view illustrating a conventional printer. Fig. 74 is an explanatory view illustrating another conventional printer. Fig. 75 is an explanatory view illustrating a still another conventional printer. DESCRIPTION OF THE EMBODIMENTS [FIRST EMBODIMENT] The following descriptions will discuss the first embodiment of the present invention in reference to Fig. 5 through Fig. 21. However, the present invention is not limited to this preferred embodiment. Fig. 5 is a block diagram showing a basic configuration of a computer system such as a word processor including a printer, a personal computer, etc. The ink ribbon cassette automatic changer printer system in accordance with the present invention, as illustrated in Fig. 5, is provided with a control and operation (hereinafter referred to as CPU (Central Processing Unit)) 1 for carrying out (1) the control of each operation of the constituent elements and (2) a variety of calculations. A memory device 3 is connected with the CPU 1. An input device 2, a display device 4, and a print device 5 are respectively connected with the CPU 1 through an I/O port 6. The memory device 3 is composed of (1) a RAM (Random Access Memory) to and from which document data, image data and a variety of variable data can be stored and can be read out (2) a ROM (Read Only Memory) in which control programs for operating the CPU 1 and other programs are stored. The input device 2 is a key board, for inputting the document data and the user's instructions, which is connected with the CPU 1 through a key interface. The input device 2 may be connected to a color image scanner (not illustrated) for inputting color image data. An LCD (Liquid Crystal Display) for displaying the document data, image data or the massages for the user is connected with the CPU 1 as the display device 4 through an LCD controller. The print device 5 is a print device (ink ribbon cassette automatic changer printer) for printing the document data and the image data. The print device 5 is provided with (1) a carriage 5-3, which is movable in a direction parallel to the platen, has a thermal head, and can hold one ink ribbon cassette, (2) a stocker 5-1 which can hold, above the carriage 5-3 in parallel, four ink ribbon cassettes in a direction parallel to the moving direction of the carriage 5-3, (3) a changer 5-2 which can remove the ink ribbon cassette held in an arbitrary position of the stocker 5-1 so as to attach it onto the carriage 5-3 or which can remove the ink ribbon cassette held by the carriage 5-3 so as to attach it to an arbitrary position of the stocker 5-1, the arbitrary position being the position where no ink ribbon cassette is held, and (4) a paper feeder 5-4 for feeding the printing paper. The stocker 5-1 is provided with (a) four stocker cassette holding sensors for detecting whether or not the respective four ink ribbon cassettes are held, and (b) a stocker close sensor for detecting whether or not the stocker 5-1 is opened so that the user can easily change the ink ribbon cassette. The changer 5-2 is provided with a changer upper end sensor and a changer lower end sensor. The changer upper end sensor is provided for judging whether or not the stocker 5-1 is in a raised state while the changer lower end sensor is provided for judging whether or not the stocker 5-1 is in a descendent state. The changer 5-2 is further provided with a motor for elevating the changer 5-2 and a driver for driving the motor. The carriage 5-3 is provided with (1) a carriage cassette holding sensor for detecting whether or not the ink ribbon cassette is held on the carriage 5-3, (2) an ink ribbon end sensor for detecting whether or not the ink ribbon is ended during the printing, (3) a printing head for carrying out the printing, (4) a driver for applying a voltage to the printing head, (5) a motor for driving the carriage 5-3, (6) a motor for making the printing head come into contact with the printing paper and for rewinding the ink ribbon and (7) two drivers for driving the respective motors (5) and (6). The paper feeder 5-4 is provided with a printing paper sensor for judging whether or not the printing paper is set, a motor for feeding the printing paper and a driver for driving the motor. Note that the outputs of the respective sensors are inputted to the CPU 1 through an I/O port 6, the drivers are driven by the CPU 1 through the I/O port 6. Figures 6 through 15 are explanatory views illustrating the ink ribbon cassette automatic changer printer 5. In Fig. 6, the stocker 5-1 can hold the ink ribbon cassettes 5-5 through 5-8, and is provided with stocker cassette holding sensors 5-1-1 through 5-1-4 for detecting whether or not the respective ink ribbon cassettes are held. Figures 7(a) and 7(b) are explanatory views illustrating the stocker cassette holding sensor 5-1-1 (the other stocker cassette holding sensors 5-1-2 through 5-1-4 have the same structure as the stocker cassette holding sensor 5-1-1). The stocker cassette holding sensor 5-1-1 uses a switch which turns on when a projection is pushed down. According to Fig. 7(a), the stocker cassette holding sensor 5-1-1 is in the off state because no ink ribbon cassette is held by the stocker 5-1. According to Fig. 7(b), the stocker cassette holding sensor 5-1-1 is in the on state because the projection is pushed down based on the fact that the ink ribbon cassette 5-5 is held by the stocker 5-1. The stocker 5-1 can be opened, as illustrated in Fig. 8(a), so that the user can change the ink ribbon cassette with ease, and is provided with a stocker close sensor 5-1-5 for detecting whether or not the stocker 5-1 is opened. Figures 8(a) and 8(b) are explanatory views illustrating the stocker close sensor 5-1-5. The stocker close sensor 5-1-5 uses a switch which turns on when a projection is pushed down. According to Fig. 8(a), the stocker 5-1 is in the open state, so the stocker close sensor 5-1-5 is in the off state. According to Fig. 8(b), the stocker close sensor 5-1-5 changes into the on state because the projection is pushed down based on the fact that the stocker 5-1 is closed. The changer 5-2 can move up and down the stocker 5-1, and is arranged so that the ink ribbon cassette is delivered between the stocker 5-1 and the carriage 5-3. The changer 5-2 has a changer upper end sensor 5-2-2 and a changer lower end sensor 5-2-3. Figures 9(a) through 9(d) are explanatory views illustrating the changer upper end sensor 5-2-2 and the changer lower end sensor 5-2-3. As illustrated in the Figures, a cam 5-2-1 rotates in synchronism with the changer 5-2. More specifically, the cam 5-2-1 rotates by 180 degrees in accordance with the movement of the stocker 5-1 from an upper end position to a lower end position. When the stocker 5-1 is in the upper end position (corresponding to zero degree), its state becomes like Fig. 9(a). In such a state, the changer upper end sensor 5-2-2 changes into the on state, while the changer lower end sensor 5-2-3 changes into the off state. When the stocker 5-1 is in the lower end position (corresponding to 180 degrees), its state becomes like Fig. 9(c). In such a state, the changer upper end sensor 5-2-2 changes into the off state, while the changer lower end sensor 5-2-3 changes into the on state. The states illustrated in Figures 9(b) and 9(d) where in the changer upper end sensor 5-2-2 and the changer lower end sensor 5-2-3 are both in the on state or both in the off state indicate the state wherein the stocker 5-1 is between the upper and lower end positions. As illustrated in Fig. 6, the carriage 5-3 is guided by a shaft 5-9 and is moved by a carriage drive mechanism (not illustrated) in parallel to a platen 5-10 so that the printing is carried out by a printing head 5-3-2. Note that the printing head 5-3-2 is a thermal head. The carriage 5-3 is provided with a carriage cassette holding sensor 5-3-1 by which it can be judged whether or not the carriage 5-3 holds an ink ribbon cassette. The carriage cassette holding sensor 5-3-1 also uses the switch similar to those of the stocker cassette holding sensors 5-1-1 through 5-1-4. The carriage 5-3 is provided with an ink ribbon end sensor 5-3-3 by which it can be detected that the ink ribbon has been ended during the printing. Fig. 10 is an explanatory view illustrating the ink ribbon end sensor 5-3-3. Fig. 10 illustrates the state where an ink ribbon 5-7-1 is sandwiched between a light emitting section 5-3-3-1 and a light receiving section 5-3-3-2 of the ink ribbon end sensor 5-3-3. There is provided with an ink ribbon end mark 5-7-2 near an end portion of the ink ribbon 5-7-1, the end portion having alternate transparent portion and non-transparent portion. In ordinary, the ink ribbon scarcely transmits the incident light, so the light does not reach the light receiving section 5-3-3-2. However, when the ink ribbon 5-7-1 is wound up in an arrow direction and the ink ribbon end mark 5-7-2 passes through the ink ribbon end sensor 5-3-3, then the light receiving section 5-3-3-2 receives light pulses and converts it into electric pulses so as to output, thereby enabling to detect that the ink ribbon has been exhausted. Fig. 11 is a view illustrating the state where the changer 5-2 moves up the stocker 5-1. The carriage 5-3 is movable in a direction parallel to a platen 5-10 only when the stocker 5-1 is in the upper end position. In Fig. 11, the stocker 5-1 holds the ink ribbon cassettes 5-5 through 5-8, while the carriage 5-3 holds no ink ribbon cassette. In order to attach the ink ribbon cassette 5-7 to the carriage 5-3, as illustrated in Fig. 12, it is required (1) to move the carriage 5-3 beneath the ink ribbon cassette 5-7, (2) to move down the stocker 5-1 by the changer 5-2, and (3) to move up the stocker 5-1 after the carriage 5-3 has held the ink ribbon cassette 5-7. Fig. 13 is a view illustrating the state where the stocker 5-1 is again moved up by the changer 5-2 after the ink ribbon cassette 5-7 is attached to the carriage 5-3. In such a state, the carriage 5-3 can carry out the printing with the use of the ink ribbon cassette 5-7. When attaching one of the other ink ribbon cassettes to the carriage 5-3, it is required (1) to move the carriage 5-3 beneath a vacant position in the stocker 5-1, (2) to move down the stocker 5-1 by the changer 5-2, and (3) to move up the stocker 5-1 after the carriage 5-3 has held the ink ribbon cassette 5-7. This causes the ink ribbon cassette 5-7 to return to the original position of the stocker 5-1, thereafter, the above-mentioned other ink ribbon cassette can be attached to the carriage 5-3 in accordance with the foregoing manner. Note that the detail explanation how to deliver the ink ribbon cassette between the stocker 5-1 and the carriage 5-3 will be later described. Fig. 14 is a view illustrating the state where the stocker 5-1 is opened. The stocker 5-1 can rotate around a stocker rotation shaft 5-1-6 so as to be opened when the stocker 5-1 remains in the upper end position as illustrated in Fig. 13, thereby ensuring that the user can change the ink ribbon cassettes 5-5 through 5-8. Since the stocker 5-1 is further provided with the stocker close sensor 5-1-5, it can be judged in accordance with the stocker close sensor 5-1-5 whether the stocker is in the opened state. Note that the stocker close sensor 5-1-5 has already been explained before with reference to Fig. 8(a). Figures 15(a) through 15(d) are explanatory views illustrating the delivery of the ink ribbon cassette 5-7 between the stocker 5-1 and the carriage 5-3. Note that since the outlines of the respective ink ribbon cassettes 5-5 through 5-8 are coincident with each other, the respective ways to deliver are the same accordingly. In Fig. 15(a), the ink ribbon cassette 5-7 is held by the stocker 5-1 through a stocker fix holding claw 5-1-7 and a stocker movable holding claw 5-1-8. The carriage 5-3 is provided with a plurality of carriage fix holding claws 5-3-4 for holding the ink ribbon cassette. When the ink ribbon cassette 5-7 held by the stocker 5-1 is attached to the carriage 5-3, the changer 5-2 (not illustrated in Fig. 15) moves down the stocker 5-1 as illustrated in Fig. 15(b). Fig. 15(b) illustrates that the ink ribbon cassette 5-7 is held by both (1) the stocker 5-1 (the stocker fix holding claw 5-1-7 and the stocker movable holding claw 5-1-8) and (2) the carriage 5-3 (the carriage holding claw 5-3-4). Next, the changer 5-2 moves the stocker movable holding claw 5-1-8 in an arrow direction of Fig. 15(c), thereby resulting in that the ink ribbon cassette 5-7 is released from the stocker 5-1. Then, the changer 5-2 moves up the stocker 5-1. With the movement, the ink ribbon cassette 5-7 is held by the carriage 5-3, thereby causing the stocker 5-1 not to hold the ink ribbon cassette 5-7 (see Fig. 15(d)). In contrast, when the ink ribbon cassette 5-7 held by the carriage 5-3 returns to the stocker 5-1 (see Fig. 15(d)), the changer 5-2 moves the stocker movable holding claw 5-1-8 in an arrow direction of Fig. 15(c) so that the stocker 5-1 moves down. Then, the changer 5-2 returns the stocker movable holding claw 5-1-8 as it was as illustrated in Fig. 15(b), i.e., holds the ink ribbon cassette 5-7 so that the stocker 5-1 moves up. The holding force exerted on the ink ribbon cassette 5-7 is enough greater in the case where it is held by the stocker fix holding claw 5-1-7 and the stocker movable holding claw 5-1-8 than in the case where it is held by the carriage holding claw 5-3-4. So, this causes that the ink ribbon cassette 5-7 is taken out from the carriage 5-3 (see Fig. 15(a)) so as to be attached to the stocker 5-1. When the changer 5-2 raises and lowers the stocker 5-1, whether or not the stocker movable holding claw 5-1-8 to be moved is determined by a cam (not shown) which rotates by the changer motor for raising or lowering the stocker 5-1. The cam is allowed to rotate by 180° to move the stocker 5-1 from the lower end to the upper end. When the cam rotates 180° in a clockwise direction, the stocker movable holding claw 5-1-8 is moved, while when the cam rotates 180° in a counterclockwise direction, the stocker movable holding claw 5-1-8 stops moving. In the present embodiment, the stocker 5-1 has the stocker movable holding claw 5-1-8 in the same number (four in this embodiment) as the number of ink ribbon cassettes that can be stored. The stocker movable holding claw 5-1-8 in each position includes a claw (not shown) to be pushed up by being in contact with the carriage 5-3 when lowering the stocker 5-1. Here, since only the claw being pushed up is moved by the cam which rotates by the changer motor (not shown), only the stocker movable holding claw 5-1-8 placed right above the carriage 5-3 can be moved. As described, the ink ribbon cassette can be delivered between the stocker 5-1 and the carriage 5-3, a continuous printing operation is performed without using an assistance of the user. The control system for automatically exchanging the ink ribbon cassette exchange control system of the printer of the present invention will be explained below in reference to the flowchart of Fig. 16. In S1, the user inputs a command for printing through the input device 2 (keyboard). In S2, the user selects the continuous printing mode using the ribbon of one color by the input device 2 (keyboard). Other possible modes include a color printing mode, two colors printing mode, etc. However, since this is not specifically related to the present invention, explanations thereof shall be omitted here. In S3, it is determined whether or not at least two ink ribbon cassettes are stored in the stocker 5-1 by the stocker cassette holding sensors 5-1-1 through 5-1-4. If only one ink ribbon cassette is stored, it is recognized as an error, and a message for setting additional ink ribbon cassette is displayed on the display device 4 (S4). In S3, if it is determined that at least two ink ribbon cassettes are stored in the stocker 5-1, it is determined that all of the ink ribbon cassettes are in the same color (S5). Here, it may be arranged so as to determined the color by color detection means provided in the stocker 5-1. Alternatively, the user may indicates which of the ink ribbon cassette is in the same color. The following explanations will be given in the case of storing four ink ribbon cassettes in the stocker 5-1. Next, in S6, among the ink ribbon cassette stored in the stocker, the arranged order from the least mount of ink ribbon cassette is inputted by the user through the input device 2 (keyboard). The described input is displayed on the display device 4 as shown in Fig. 18, and the number of the kink ribbon cassette is inputted from that has the least amount of ink ribbon. For example, in the case where the ink ribbon cassette set in the middle left position (second ink ribbon cassette from the left) of the stocker 5-1 has the least amount of the ink ribbon, the ink ribbon cassette set in the middle right position (third ink ribbon cassette from the left) of the stocker 5-1 has the second least amount of the ink ribbon, the ink ribbon cassette set in the left end position has the second largest amount of the ink ribbon cassette, and the ink ribbon cassette set in the right end position has the largest amount of the ink ribbon cassette, the numbers are inputted through the input device 2 (keyboard) in the order of 2, 3, 1 and 4. The information indicative of the remaining amount of ink ribbon cassette inputted in S6 is stored in predetermined addresses of the memory device 3 as shown in Fig. 19. For example, when the numbers are inputted in the described order, as shown in Fig. 19, numbers are stored in the order of 3, 1, 2 and 4 from the address of +0. Here, if the order of the ink ribbon cassettes from the least amount of the ink ribbon is not inputted by the user, for example, when the cancel key is operated in S6, the numbers are stored from the address of +0 in the order of 1, 2, 3 and 4 in the memory device 3. In this embodiment, the order indicating the remaining amount of ink ribbon is inputted by the user through the input device 2 to be stored in the memory device 3. However, the percentage of the remaining amount of the ink ribbon cassette may be detected automatically by providing an ink ribbon remaining amount detecting device. The described method of detecting the ink ribbon remaining amount is a known technique as disclosed by Japanese Laid-Open Patent Application No. 187779/1991 (Tokukaihei 3-187779). In the next stage, the ink ribbon cassette which has the least remaining amount of the ink ribbon is determined based on the information indicating the ink ribbon remaining amount (see Fig. 19) stored in the memory device 3. Then, the ink ribbon cassette is take out of the stocker 5-1 by the changer 5-2 to be set on the carriage 5-3 (S8), and a printing operation is executed (S9). In S10, it is determined whether or not an input is made for stopping a printing operation from the input device 2 (keyboard) by the user. If so, the sequence goes onto S31, and if not, the sequence moves onto S11. In S11, it is determined that the ink ribbon is used to the end by the ink ribbon end sensor 5-3-3 during the printing operation, the printing operation is temporarily stopped (S12), and a message "ink ribbon cassette being exchanged" is displayed on the display device 4 in S13, so as to inform the user of the fact that the case of the stoppage of the printing operation is not the operation error. The ink ribbon cassette which is used up is taken out of the carriage 5-3 by the changer 5-2 and is set at the initial position of the stocker 5-1 (step S14 and S15). Here, the set position of this cassette is stored in a predetermined address of he memory device 3 as the information indicative of the used-up ink ribbon cassette holding position (=1) as shown in Fig. 20 (S16). In the example shown in Fig. 20, the information "1" is stored in the address of +5 and the address of +6, while information of "0" is stored in other addresses. Therefore, the respective ink ribbon cassettes stored in the middle left position (second ink ribbon cassette from the left end) and the ink ribbon cassette stored in the middle right position (the third ink ribbon cassette from the left end) are used up, while the other ink ribbon cassettes have not being used up. In S17, it is determined whether or not all of the ink ribbon cassettes stored in the stocker 5-1 have being used up based on information indicative of the end of the ink ribbon cassette holding position stored in the memory device 3 as shown in Fig. 20. If so, i.e., all of the information indicative of the end of ink ribbon cassette holding position are "1", the user is informed of the exchange of the ink ribbon cassette, for example, by displaying it on the display device (S18). In the case where the described condition is not satisfied, i.e., at least two information indicating the ink ribbon cassette holding position exist, the ink ribbon cassette having the second least amount of the ink ribbon cassette is determined based on the information indicating the remaining amount of ink ribbon and the information indicating the end of ink ribbon cassette holding position. Then, the ink ribbon cassette is take out of the stocker 5-1 by the changer 5-2 to be mounted on the carriage 5-3 (S19 and S20). In the case shown in Fig. 19 and Fig. 20, the ink ribbon cassette in the left end position is set. Thereafter, the interrupted printing operation is restarted (S21). After the printing operation has been completed, the user is informed of the message of exchanging the ink ribbon cassette stored in the position corresponding to the position where the information indicating the used ink ribbon cassette holding position of the stocker 5-1 is 1, and is displayed on the display device 4, for example, as shown in Fig. 21 (S23). Fig. 21 shows that the ink ribbon cassette set in the middle left position (second ink ribbon cassette from the left end) and the ink ribbon cassette to be stored in the middle right position (third ink ribbon cassette from the left end) are used up. On the other hand, in S10, when the user inputs an instruction for stopping the printing operation through the input device 2 (keyboard), as shown in Fig. 17, the printing operation is interrupted in S31, and the ink ribbon cassette being used is taken out of the carriage 5-3 by the changer 5-2 to be set in the initial position of the stocker 5-1 (S32 and S33). Next, in S34, the ink ribbon cassette which has been used up is determined based on the information indicative of the end of ink ribbon holding position (Fig. 20), and inform the user of the used up ink ribbon cassette using the display device 4 as shown in Fig. 21. When installing and taking out the ribbon in and of the stocker 5-1, the stocker 5-1 is set in the open position. Here, the stocker closing sensor 5-1-5 determines that the stocker 5-1 is set in the open position (S35), and the installation and removal of the ink ribbon cassette are determined by the stocker cassette holding sensors 5-1-1 through 5-1-4 (S36). Moreover, when the stocker closing sensor 5-1-5 determines that the stocker 5-1 is closed (S37), the information indicative of the end of ink ribbon cassette position memory is cleared to "0" after the removal and the installation of the ink ribbon cassette are performed (S38), and the sequence goes back to S6. Here, it may also arranged so as to determine that the used up ink ribbon cassette is taken out and is exchanged with new ink ribbon cassette, and to automatically renew the stored number for the information indicative of the remaining amount of the ink ribbon cassette to have the information "1" indicative of the ink ribbon remaining amount in the position where the removal and the installation of the ink ribbon are performed. Here, as shown in Fig. 20, the information related to the middle left ink ribbon cassette (second from the left) and the information related to the middle right ink ribbon cassette (third from the left) are "1" indicating that theses cassettes are used up as shown in Fig. 20, after the stocker closing sensor 5-1-2 (middle left - second sensors from the left) detects the installation and the removal of the ink ribbon cassette, the values of the information are stored in the order of 0, 0, 1 and 0 from the left end in Fig. 20. The ink ribbon cassette exchange control by the CPU is performed in accordance with the described flowchart. [SECOND EMBODIMENT] The second embodiment of the present invention will be explained below in reference to Fig. 22 through Fig. 27. However, the present invention is not limited to this preferred embodiment. In the present invention, the basic configuration of the computer system such as a word processor, a personal computer including a printer, etc., is the same as the described first embodiment. Therefore, for convenience in explanations, members having the same functions as those shown in the previous embodiment will be designated by the same reference numerals, and the descriptions thereby shall be omitted here. Fig. 22 is a flowchart showing the controlling process for lowering the stocker by the CPU 1. While a printing operation is being executed using an ink ribbon cassette in one color, if it is required to exchange with an ink ribbon cassette in another color, it is required to lower the stocker 5-1. For example, after performing a printing operation using an ink ribbon cassette in yellow, if a printing operation using a black ink ribbon is required, the CPU 1 recognizes a necessity of lowering the stocker 5-1. In S51, it is determined whether or not it is necessary to lower the stocker 5-1. If so, the sequence goes onto the step S52. If not, the process is terminated. In S52, it is determined whether or not the stocker 5-1 is closed based on the output from the stocker closing sensor 5-1-5. If so, the sequence goes onto S54, and if not, the sequence moves onto S53. In the determination, the opening and closing information of the stocker, i.e., output information from the stocker closing sensor is stored in the RAM of the memory device 3. For example, the CPU 1 alters the opening and closing information by reading out an output from the stocker closing sensor 5-1-5. In S54, the process is completed when the stocker 5-1 is lowered. The process of lowering the stocker is performed by the CPU 1 by controlling an operation of a stocker according to the program prepared beforehand. On the other hand, in S53, an error handling such as displaying a message such as "close a stocker", etc., for example, on the display device 4, and the sequence goes back to S52. By the described control, an occurrence of such an inconvenience that the changer is operated in spite of the fact that the stocker is opened can be prevented. The flowchart showing a control process for exchanging an ink ribbon cassette will be shown in Fig. 23. The following process is performed also under the control of the CPU 1. When the user gives an instruction for exchanging an ink ribbon cassette by an input device 2 (keyboard), etc., if the ink ribbon cassette in the same color as the ink ribbon cassette used in the current printing operation is not stored in the stocker 5-1, the following process is executed. Here, the ink ribbon use-up sensor 5-3-3 is provided for detecting the used up ink ribbon. In S61, it is determined whether or not the ink ribbon cassette is stored in a carriage 5-3 by a carriage cassette holding sensor 5-3-1. If so, the sequence goes back to S62, and if not, the sequence goes onto S67. In S67, it is determined whether or not a changer 5-2 raises the stocker 5-1 to an upper limit position by a changer upper limit sensor 5-2-2 and a changer lower limit sensor 5-2-3. If so, the sequence goes onto S69, and if not the sequence moves onto S68. In S62, it is determined whether or not the changer 5-2 lowers the stocker 5-1 to the lower limit position by the changer lower limit sensor 5-2-3 and the changer upper limit sensor 5-2-2. If so, the sequence goes onto S68. If not, the sequence goes onto S63. In S63, it is determined whether or not the changer 5-2 raises the stocker 5-1 to the upper limit position by the changer upper limit sensor 5-2-2 and the changer lower limit sensor 5-2-3. If so, the sequence directly goes to S65, and if not, the sequence moves onto S64. The sequence moves to the S64 only when the abnormal condition has occurred where the stocker 5-1 is not at the lower limit position nor the upper limit position. This may occur when the user forces the stocker to be raised or lowered. In S64, the changer 5-2 raises the stocker 5-1 to the upper limit position by cancelling the holding of the ink ribbon cassette. In S65, the carriage 5-3 is moved to the position where the ink ribbon cassette of the stocker 5-1 is not held. Here, the position where the ink ribbon cassette of the stocker 5-3 is not held is determined by the stocker cassette holding sensor 5-1-1 through 5-1-4. In S66, the changer 5-2 lowers the stocker 5-1 to the lower limit position by cancelling the holding of the ink ribbon cassette of the stocker 5-1, and the sequence moves onto S68. In S68, the changer 5-2 raises the stocker 5-1 to the upper limit while holding the ink ribbon cassette of the stocker 5-1. As a result, the holding of the ink ribbon cassette is switched from the carriage 5-3 to the stocker 5-1, and the stocker 5-1 is held at the upper limit position. In S69, a message such as "exchange ribbon cassette in the stocker", etc., is displayed on the display device 4 so as to urge the user to exchange the ink ribbon cassette in the stocker 5-1. Reading the message, the user rotates (opens) the stocker 5-1 to exchange the ink ribbon cassette in the stocker 5-1 with a new ink ribbon cassette. In S70, the user determines whether or not the stocker 5-1 is set in the open position by the stocker closing sensor 5-1-5. If so, the sequence moves onto S71. The exchange of the cassette in S71 is required when the user sets the ink ribbon cassette in the carriage 5-3 by mistake while exchanging the ink ribbon cassette. The process in S71 will be explained later. In S72, it is determined whether or not the ink ribbon cassette has been exchanged by the user. The determination may be carried out by the completion instructing method by the user through the input device 2 (keyboard), or by the method for detecting that the ink ribbon cassette is set in the stocker 5-1 by the stocker cassette holding sensors 5-1-1 through 5-1-4. In S73, it is determined whether or not the stocker 5-1 is set in the close position by the user using the stocker closing sensor 5-1-5. If not, the sequence moves onto S74. In S74, a message such as "close a stocker", etc., is displayed on the display device 4 so as to urge the user to close the stocker 5-1, and the sequence goes back to S73. If it is determined in S73 that the stocker 5-1 is closed, the sequence is terminated. Fig. 24 is a flowchart which explained the process in S71 in Fig. 23 in detail. In the arrangement of the present embodiment, a device for determining the type of the ink ribbon cassette such as color, etc., is not provided. Therefore, it is arranged such that the color of the ink ribbon cassette is determined by the holding position of the ink ribbon cassette of the stocker 5-1. If not specified, the color is set in the order of black, yellow, magenta and cyan from the left, and the color information of the holding position is stored in the memory device 3 as shown in Fig. 25. In the memory position having the address of +0 of the memory device 3, the color of the ink ribbon cassette to be held in the left end of the stocker 5-1 is stored, and in Fig. 25, the name of the color "black" is stored. Similarly, in the memory position having an address +1, the name of the second color from the left, is stored, in the memory position having the address of +2, the name of the second color from the right is stored, and in the memory position having the address of +3, the name of the color to be stored in the right end position of the stocker 5-1 is stored. For example, when the user sets the ink ribbon cassette to the left end of the stocker, the CPU 1 recognizes that the stock cassette holding sensor 5-1-1 is turned ON, and it is recognized that the ink ribbon cassette is in black based on the information stored in the address of +0 in Fig. 25 in the memory device 3. In the present embodiment, the color of the ink ribbon cassette is determined in the described manner, if the user stores the ink ribbon cassette directly in the carriage 5-3, the CPU 1 cannot determine the color of the ink ribbon cassette. As a note, even if the ink ribbon cassette is stored in the carriage 5-3 by the user, if an empty space, i.e., a space where the ink ribbon cassette is not set in the stocker 5-1 is only one, the CPU 1 can recognize that the ink ribbon cassette set on the carriage 5-3 is in a color corresponding to the empty space. In S70 of Fig. 23, after it is determined that the stocker 5-1 rotates (open position), the sequence moves onto S71, i.e., the process in the flowchart of Fig. 24. In S81 of Fig. 24, it is determined whether or not the ink ribbon cassette is held in the carriage 5-3 by the cassette holding sensor 5-3-1 of the carriage. If so, the sequence moves onto S82. If not, on the other hand, the process is terminated. In S82, it is determined whether or not a single empty space where the ink ribbon cassette is not held in the stocker 5-1 by the stocker cassette holding sensors 5-1-1 through 5-1-4. If so, the sequence moves onto S83. If not on the other hand, the sequence moves onto the step S84. In S83, the empty position of the stocker 5-1 detected in S82 and the information shown in Fig. 25 stored in the memory device 3, the kind of the ink ribbon cassette set on the carriage 5-3, the name of the color in this example are recognized, thereby terminating the process. On the other hand, in S84, the color of the ink ribbon cassette on the carriage 5-3 cannot be recognized, a message "remove the ribbon cassette from the carriage", etc., is displayed on the display device so as to urge the user to remove the ink ribbon cassette from the carriage 5-3. Then, the sequence goes back to S81. The processes in S81-S84 are repeated, and the process will not be terminated until it is detected that the ink ribbon cassette is taken out from the carriage 5-3, or a space is formed in the stocker 5-1. Namely, the printing operation will not be started. The above-mentioned process is an inform processing in the case where the ink ribbon is set on the carriage by mistake. Fig. 26 shows another detained flowchart of S71 in Fig. 23. In the flowchart of Fig. 24, the user sets the ink ribbon cassette directly to the carriage 5-3, and if multiple empty spaces are formed in the stocker 5-1, the color of the ink ribbon cassette cannot be determined. Therefore, either the ink ribbon cassette is taken out of the carriage 5-3, or set such that the printing operation is not started until a single empty space is left in the stocker. In the flowchart of Fig. 26, as in the case of the flowchart of Fig. 24, by the inputs of the name of the color, i.e., the type of the ribbon cassette made by the user, the CPU recognizes the type of the ink ribbon cassette. After it is determined in S70 in Fig. 23 that the stocker is rotated, i.e., the stocker is held in the open position, the sequence moves onto S71 in the flowchart of Fig. 26. In S91 of Fig. 26, it is determined whether or not the ink ribbon cassette is stored in the carriage 5-3 by the carriage cassette holding sensor 5-3-1. If so, the sequence moves onto S92. If not, the process is terminated. In S92, it is determined whether or not only a signal empty space is left in which the ink ribbon cassette is stored in the stocker 5-1 by the stocker cassette holding sensors 5-1-1 through 5-1-4. If so, the sequence goes onto the step S93, and otherwise, the sequence moves onto S94. In S93, the kind (color in this example) of the ink ribbon cassette mounted on the carriage 5-3 is recognized based on the empty position of the stocker 5-1 detected in S92 and information shown in Fig. 25, thereby terminating the process. On the other hand, in S94, the color of the ink ribbon cassette on the carriage 5-3 is not recognized. Therefore, the user is informed to input the color of the set ink ribbon cassette. The user may input in the manner shown in Fig. 27, the kind of the ink ribbon cassette is displayed, and the input device 2 is selected among them. In S95, it is determined whether or not the ink ribbon cassette inputted in S94 is of a special kind. If so the sequence goes onto S96. If not, the sequence moves onto S97. A special color for the ink ribbon cassette suggests a color which is not stored in the memory device 3 beforehand as shown in Fig. 25 (such as black, yellow, magenta, cyan). Examples of such special color includes: red, blue, gold, silver, etc., or a label cassette (an ink ribbon and a paper ribbon are stored in the ink ribbon cassette, and a print is made on the paper ribbon). In S96, the printing mode is switched according to the kind of the ink ribbon cassette inputted in S95. In general, for example, in the color printing mode, i.e., the seven color printing is performed using the ink ribbon cassettes in black, yellow, magenta and cyan, however, if an input is made to indicate that the red ink ribbon cassette is mounted, the printing mode is switched to the two color printing mode (for performing two color printing using the ink ribbon cassettes in black and red), or if an input is made to indicate that label cassette is set, the printing mode is switched to the label cassette printing mode (for the restriction in the number of characters which can be printed in one time or for altering the width of a voltage pulse to be applied to the thermal head). On the other hand, in S97, based on the kind of the ink ribbon cassette inputted in S94 and the information stored in the memory 3 shown in Fig. 25, it is determined whether or not the corresponding position in the stocker 5-1 is empty, i.e., the ink ribbon cassette is not held. If so, the sequence is terminated, and if not the sequence moves onto S98. In S98, since it is determined that the ink ribbon cassette of the same type (in the same color) as that mounted on the carriage 5-3 is already set in the stocker 5-1, the user is informed of taking out the ink ribbon cassette on the carriage 5-3. Namely, a message such as "remove the ribbon cassette from the carriage" is displayed on the display device 4. As a result, the sequence goes back to S91. This is because when the ink ribbon cassette on the carriage 5-3 is to be exchanged with an other ink ribbon cassette held in the stocker 5-1 by the changer 5-2, the ink ribbon cassette on the carriage 5-3 would not be moved back to the stocker 5-1. The above-mentioned process is the control and informing process to be performed when the ink ribbon cassette is set on the carriage. Here, even if the ink ribbon cassette is mounted on the carriage, the printing operation would be performed in an appropriate color, thereby easily switching the set printing mode. [THIRD EMBODIMENT] The following description deals with the third embodiment in accordance with the present invention with reference to Figures 28 through 50. Note that the present invention is not restricted to the present embodiment. The present embodiment deals with an ink ribbon cassette automatic changer printer system as one example wherein the printing is carried out by automatically changing four ink ribbon cassettes whose ink ribbon colors are respectively Y (yellow)/M (magenta)/C (cyan)/B (black). Note that the basic structure of the system of the present embodiment is the same as the first embodiment except for the following points. So, for convenience sake, the members having the same functions as those of the first embodiment have the same reference numerals as those of the first embodiment, and the explanations thereof are omitted here. A printer system in accordance with the present embodiment, as illustrated in Fig. 28, has, in the respective four ink ribbon cassette holding positions of the stocker 5-1, three sensors A through C, which are substituted for the foregoing stocker cassette holding sensors 5-1-1 through 5-1-4, for detecting what types of the ink ribbon cassettes are attached to the stocker 5-1. The sensor A has totally 4 stocker cassette type identification sensors 5-1-1-1 through 5-1-1-4. The sensor B has totally 4 stocker cassette type identification sensors 5-1-2-1 through 5-1-2-4. The sensor C has totally 4 stocker cassette type identification sensors 5-1-3-1 through 5-1-3-4. The sensors A through C are totally composed of 12 stocker cassette type identification sensors. According to the combinations of the sensor A (the stocker cassette type identification sensors 5-1-1-1 through 5-1-1-4, the sensor B (the stocker cassette type identification sensors 5-1-2-1 through 5-1-2-4) and the sensor C (the stocker cassette type identification sensors 5-1-3-1 through 5-1-3-4), it is identified (1) whether or not the ink ribbon cassettes are held in the respective ink ribbon cassette holding positions of the stocker 5-1 and (2) what types (colors) of the respective ink ribbon cassettes are held. Figures 29(a) through 29(d) are explanatory views illustrating identification holes for identifying the types of the respective ink ribbon cassettes. An ink ribbon cassette 6-1, as illustrated in Fig. 29(a), is provided with three identification holes 6-1-1 through 6-1-3 in respective predetermined positions. As illustrated in Fig. 29(b), when the ink ribbon cassette 6-1 is held by the stocker 5-1, (1) the stocker cassette type identification sensor 5-1-1-1 of the sensor A is located in the position of the identification hole 6-1-1, (2) the stocker cassette type identification sensor 5-1-2-1 of the sensor B is located in the position of the identification hole 6-1-2, and (3) the stocker cassette type identification sensor 5-1-3-1 of the sensor C is located in the position of the identification hole 6-1-3. Figures 29(c) and 29(d) are detail explanatory views illustrating the stocker cassette type identification sensor 5-1-1-1 of the sensor A, the stocker cassette type identification sensor 5-1-2-1 of the sensor B, and the stocker cassette type identification sensor 5-1-3-1 of the sensor C. Note that the stocker cassette type identification sensors 5-1-1-2 through 5-1-1-4 of the sensor A, the stocker cassette type identification sensors 5-1-2-2 through 5-1-2-4 of the sensor B, and the stocker cassette type identification sensors 5-1-3-2 through 5-1-3-4 of the sensor C, these sensors being provided in other ink ribbon cassette holding position of the stocker 5-1, are similar to the foregoing. The stocker cassette type identification sensor 5-1-1-1 of the sensor A, the stocker cassette type identification sensor 5-1-2-1 of the sensor B, and the stocker cassette type identification sensor 5-1-3-1 of the sensor C are the switches which become the on state upon pushing down respective projections. According to Fig. 29(c), the stocker cassette type identification sensor 5-1-1-1 of the sensor A, the stocker cassette type identification sensor 5-1-2-1 of the sensor B, and the stocker cassette type identification sensor 5-1-3-1 of the sensor C are all in the off state since no ink ribbon cassette is held by the stocker 5-1. In contrast, according to Fig. 29(d), when an ink ribbon cassette 6-2 in which identification holes 6-2-1 and 6-2-3 are opened is attached, the stocker cassette type identification sensor 5-1-1-1 of the sensor A and the stocker cassette type identification sensor 5-1-3-1 of the sensor C are in the off state, while the stocker cassette type identification sensor 5-1-2-1 of the sensor B is the on state. Fig. 30 is an explanatory view illustrating the relation between the identification hole and the ribbon type of the ink ribbon cassette. Thus, the identification holes which are provided in the respective ink ribbon cassettes beforehand in accordance with the types thereof are detected by the stocker cassette type identification sensors of the sensors A through C, and it is identified in accordance with the combinations of the detected results whether or not the ink ribbon cassettes exist and what types of the attached respective ink ribbon cassettes. Fig. 35 is a flow chart showing what procedures are made for printing to the thermosensible paper. According to the procedures, when the printing is carried out with respect to the thermosensible paper which does not need the ink ribbon cassette, the ink ribbon cassette 5-7 is controlled so as to be automatically taken out from the carriage 5-3. First, in S101, when the printing mode in which the printing is carried out with respect to the thermosensible paper is selected, S102 is proceeded so that it is detected by the carriage cassette holding sensor 5-3-1 whether the ink ribbon cassette 5-7 is not held by the carriage 5-3. If not, S110 is proceeded so as to start the printing. In S102, if the ink ribbon cassette 5-7 is held by the carriage 5-3, S103 is proceeded so that the stocker cassette holding sensors 5-1-1 through 5-1-4 detect what ink ribbon cassettes are held by the stocker 5-1. Then, S104 is proceeded, and it is judged whether or not the stocker 5-1 has a vacant ink ribbon cassette holding position. If the vacant ink ribbon cassette holding position exists, S105 is proceeded so that the carriage 5-3 moves under the vacant ink ribbon cassette holding position. The changer 5-2 moves the ink ribbon cassette 5-7 held by the carriage 5-3 to the vacant ink ribbon cassette holding position of the stocker 5-1 (S106). Thus, the carriage 5-3 holds no ink ribbon cassette, then the printing starts in S110. If the stocker 5-1 has no vacant ink ribbon cassette holding position in S104, S107 is proceeded. More specifically, in S107, the message for the user such as "Please take out the ink ribbon cassette from the carriage" is displayed by the display device 4, thereby alarming and informing the user that it is requested to take out the ink ribbon cassette 5-7 from the carriage 5-3. Thus, the user takes out the ink ribbon cassette 5-7 from the carriage 5-3 in accordance with the request (S108). It is detected by the carriage cassette holding sensor 5-3-1 provided in the carriage 5-3 whether or not the ink ribbon cassette 5-7 has been taken out in S109. If not, returning to S107, it is requested again that the user should take out the ink ribbon cassette 5-7 from the carriage 5-3. If it is confirmed that the ink ribbon cassette 5-7 has been taken out from the carriage 5-3 in S109, then the printing starts in S110. Thus, the printing with respect to the thermosensible paper is carried out in accordance with the foregoing steps. Fig. 36 is a flow chart showing what procedures are made for checking what ink ribbon cassettes are held by the stocker before and after the movement of the changer. Such a procedure is for promptly detecting the printer operating error such as the error of the changer 5-2 based on the fact that (1) the holding state of the ink ribbon cassettes of the respective stocker 5-1 and carriage 5-3 after the changer 5-2 operation is foreseen in accordance with those before the changer 5-2 operation, and (2) the foreseen holding state is compared with the actual holding state after the changer 5-2 operation. More specifically, the holding state of the ink ribbon cassettes of the stocker 5-1 and carriage 5-3 is detected by the stocker cassette holding sensors 5-1-1 through 5-1-4 and by the carriage cassette holding sensor 5-3-1 (S201). Then, the detected results are stored in the RAM of the memory device 3 (S202). The position, in which the stocker 5-1 having the ink ribbon cassette required for the printing is held, is identified (S203). After the identification, the carriage 5-3 is moved under the identified position (S204). The ink ribbon cassette 5-7 is attached to the carriage 5-3 by the changer 5-2 (S205). After the changer 5-2 operation, the holding state of the ink ribbon cassettes of the carriage 5-3 is detected by the carriage cassette holding sensor 5-3-1 (S206). The holding states of the respective ink ribbon cassettes of the stocker 5-1 are detected by the stocker cassette holding sensors 5-1-1 through 5-1-4 (S207). In S208, the holding states of the respective ink ribbon cassettes of the case where the changer 5-2 have appropriately operated obtained based on those which are stored in the memory device 3 in S208 and are before the changer 5-2 operation. For example, in the case where (1) the stored holding states of the respective ink ribbon cassettes that are stored in the memory device 3 in S208 before the changer 5-2 operation are shown in Fig. 41 and (2) the ink ribbon cassette in the left end position of the ink ribbon cassette holding positions of the stocker 5-1 is moved to the carriage 5-3 by the changer 5-2, (a) the holding state of the ink ribbon cassette in the left end position of the ink ribbon cassette holding positions of the stocker 5-1 changes into "non-existence" and (b) the holding state of the ink ribbon cassette in the carriage 5-3 changes into "existence" provided that the changer 5-2 have appropriately operated (see Fig. 42). In S209, it is confirmed by the comparison whether or not the actual holding states detected in S207 and S208 are coincident with those which should be after the changer 5-2 operation. If not, it is judged that some error occurs in the changer 5-2 operation, and S220 is proceeded. In S220 , the display device 4 displays the message such as "The changing of the ink ribbon cassette has been mistakenly carried out, so please check the printer", thereby alarming and informing the user that some error has occurred and thereby suspending the printing operation. On the contrary, when it is confirmed that the ink ribbon cassette holding states are coincident with each other and the changer 5-2 operation is correctly carried out in S209, S210 is proceeded. In S210, the printing is carried out by the ink ribbon cassette attached to the carriage 5-3. When the the printing is finished by the ink ribbon cassette held by the carriage 5-3, the ink ribbon cassette holding states of the stocker 5-1 and the holding state of the carriage 5-3 are detected (S211). Then, the detected results are stored in the memory device 3 as the ink ribbon cassette holding state of before the changer 5-2 operation (S212). A holding position is obtained in S213 so as to return, the ink ribbon cassette which has been used during the printing and is held by the carriage 5-3, to the original holding position of the stocker 5-1. The carriage 5-3 is moved under the original holding position of the ink ribbon cassette in the stocker 5-1 (S214). The ink ribbon cassette of the carriage 5-3 is returned by the changer 5-2 to the original ink ribbon cassette holding position of the stocker 5-1 (S215). After the changer 5-2 operation, the ink ribbon cassette holding state of the carriage 5-3 is detected by the carriage cassette holding sensor 5-3-1 (S216). The ink ribbon cassette holding states of the stocker 5-1 are detected by the stocker cassette holding sensors 5-1-1 through 5-1-4 (S217). In S218, the ink ribbon holding states of the case where the changer 5-2 has appropriately operated are obtained in accordance with the ink ribbon holding states of before the changer 5-2 operation which has been stored in the memory device 3 in S212. The way to obtain the ink ribbon holding states is similar to that of S208. The correct holding states, obtained in S218, of after the changer 5-2 operation are compared with the actual ink ribbon holding states obtained in S216 and S217 (S219). If both holding states are coincident with each other, it is judged that the changer 5-2 operation has been appropriately carried out, thereby ending the procedure. On the contrary, in S219, when the actual ink ribbon holding states are not coincident with the due holding states, S220 is proceeded. In S220, the display device 4 displays the message such as "The changing of the ink ribbon cassette has been mistakenly carried out, so please check the printer.", thereby alarming and informing the user that some error has occurred and thereby suspending the procedure. In accordance with the foregoing manner, it is checked, each time the ink ribbon cassette is attached to the carriage 5-3 or each time the ink ribbon cassette is returned to the stocker 5-1, whether or not some errors occur. With the foregoing procedures, the holding states of the respective ink ribbon cassettes are checked after and before the changer movement. Figures 37 and 38 are flow charts showing what procedures are made for checking the ink ribbon cassette holding states of the stocker for a predetermined time interval during the printing. Such procedures are made for earlier detecting the printer errors, such as the error in which the ink ribbon cassette is separated from the stocker 5-1 during the printing, based on the checking whether or not some errors occur in accordance with the ink ribbon cassette holding states detected in time interval T during the printing (see Fig. 37). As illustrated in Fig. 38, the ink ribbon cassette holding states of the carriage 5-3 and the stocker 5-1 are detected by the carriage cassette holding sensor 5-3-1 and by the stocker cassette holding sensors 5-1-1 through 5-1-4 (S301). The detected ink ribbon cassette holding states are stored in the RAM of the memory device 3 (S302). A timer by which the checking is carried out in the time interval T is reset (t=0) in S303. Note that the timer is included in the CPU 1. Then, the timer starts (S304). It is first checked whether or not the printing is being carried out (S305). If not, the procedure is ended. If it is judged to be in the printing operation in S305, S306 is proceeded for checking whether or not the changer 5-2 has been operated. If so, there occurs some difference from the ink ribbon cassette holding states stored in S302. Therefore, the ink ribbon cassette holding state of the carriage 5-3 is detected in S308 and the ink ribbon cassette holding states of the stocker 5-1 are detected in S309. The ink ribbon cassette holding states stored in S302 are replaced with the detected ink ribbon cassette holding states in S309 (S310), thereafter returning to S305. When the changer 5-2 has not operated in S306, S307 is proceeded for checking whether or not the time interval T has been elapsed. If not yet elapsed, S305 is again proceeded. If the time has been elapsed in S307, S311 is proceeded. In S311, the current ink ribbon cassette holding states of the carriage 5-3 and the stocker 5-1 are detected by the carriage cassette holding sensor 5-3-1 and by the stocker cassette holding sensors 5-1-1 through 5-1-4. Such detected results are compared with the ink ribbon cassette holding states stored in the memory device 3 (S312). If the states are not coincident with each other (S313), S314 is proceeded. In S314, the display device 4 displays the message such as "Some errors occur in the printer, so please check the printer", thereby alarming and informing the user thereof. In contrast, if the states are coincident with each other in S312, it is judged that the printer operation has been appropriately carried out, thereby returning to S303 from S313. Then, the timer is again reset and the timer starts again so as to prepare the next checking which is carried out after time interval T has elapsed. Thus, during over the printing operations, (1) the stored ink ribbon holding states stored in the memory device 3 are updated each time the changer 5-2 is operated and (2) the ink ribbon cassette holding states are checked in the time interval T, thereby checking whether or not some error occurs. Note that the time interval T is not always constant. For instance, without using the timer, the ink ribbon cassette holding states can be detected each time the printing by one line is carried out. In accordance with the foregoing procedures, the ink ribbon cassette holding states of the stocker in every the predetermined period of time are checked during the printing. Fig. 39 is a flow chart showing what procedures are made for checking the ink ribbon cassette holding states of the stocker prior to the printing. Such procedures are made to confirm the user whether or not the ink ribbon cassettes are attached to the stocker 5-1 prior to the printing so as to identify (1) the types of the ink ribbon cassettes required for the printing and (2 ) the positions of the stocker 5-1 for holding the respective ink ribbon cassettes. Since the required number and types of the ink ribbon cassettes vary depending on the printing mode, the data of Fig. 43 relating to appropriate ink ribbon cassette holding states are stored in the memory device 3 beforehand. Note that no ink ribbon cassette is necessary to be held in the position represented as "arbitrary" in Fig. 43. First, the printing mode is selected (S401). The ink ribbon cassette holding states of the stocker 5-1 are detected by the stocker cassette holding sensors 5-1-1 through 5-1-4 (S402). Such detected results are compared with the ink ribbon cassette holding states stored in the memory device 3 which correspond to the printing mode (S403). If the ink ribbon cassettes are not attached to the holding positions of the stocker 5-1 to which the respective ink ribbons should be attached (S404), S405 is proceeded. In S405, the display device 4 alarms and informs the user that the ink ribbon cassette is mistakenly attached. After the user attached the ink ribbon cassette to the correct holding position (S406), S402 is proceeded for checking again the ink ribbon cassette holding states of the stocker 5-1. In contrast, in S404, the ink ribbon cassette holding states of the stocker 5-1 are coincident with the ink ribbon cassette holding states stored in the memory device 3 which correspond to the selected printing mode, S407 is proceeded. In S407, the display device 4 displays (1) the types of the ink ribbon cassettes required for the printing and (2) the positions of the stocker 5-1 for holding the respective ink ribbon cassettes as shown in Fig. 44 by referencing to the appropriate ink ribbon cassette holding states data (see Fig. 43) stored in the memory device 3, thereby informing and confirming the user thereof. Thereafter, S408 is proceeded for starting the printing. Thus, the ink ribbon cassette holding states of the stocker are checked prior to the printing. Fig. 40 is a flow chart showing what procedures are made for correctly printing by checking the ink ribbon cassette holding states of the stocker prior to the printing. Such procedures are made for correctly printing irrespective of the holding positions of the stocker 5-1 in the case where it is judged that the required ink ribbon cassettes are all prepared upon checking prior to the printing whether or not the ink ribbon cassettes required for the selected printing mode are attached to the stocker 5-1. Here, it is only necessary to identify what color ink ribbon cassettes are attached to the respective positions of the stocker 5-1. In the case where no stocker cassette type identification sensors are provided, it may be arranged so that the user inputs the types of the respective ink ribbon cassettes attached to the stocker 5-1 so as to be inputted from the ink ribbon cassette on the left side end to the ink ribbon cassette on the right side in order. More specifically, the printing mode is first selected (S501). The holding states and types of the ink ribbon cassettes in the stocker 5-1 are detected by the sensor A (the stocker cassette type identification sensors 5-1-1-1 through 5-1-1-4), the sensor B (the stocker cassette type identification sensors 5-1-2-1 through 5-1-2-4) and the sensor C (the stocker cassette type identification 5-1-3-1 through 5-1-3-4). In accordance with the detected results, it is checked whether or not all the types of the ink ribbon cassettes required for the printing mode selected in S501 are attached to the stocker 5-1 (S503). The types of the ink ribbon cassettes required for the printing mode have been stored in the memory device 3 as illustrated in Fig. 43. In S503, it is judged whether or not the results of S502 are coincident with the stored ones. Note that the coincidence of the holding positions is not necessary but the coincidence of the types and number is necessary. When one type of the ink ribbon cassettes is not coincident, the step proceeds from S504 to S505. In S505, the display device 4 alarms and informs the user that the ink ribbon is mistakenly attached. The display device 4 displays so as to alarm and inform the user that (1) ink ribbon cassette required for the printing which has been judged not to be attached in S502 and (2) its holding position in which the ink ribbon cassette should be held in the stocker 5-1 (S506). In accordance with the alarmings and informings of S505 and S506, the ink ribbon cassette is attached by the user in S507. Thereafter, returning to S502, it is checked whether or not all the types of the ink ribbon cassettes required for the printing are attached to the stocker 5-1 again. When it is judged that all the types of the ink ribbon cassettes required for the printing are attached to the stocker 5-1 in S502 and S503, the step proceeds from S504 to S508 so that the types and the holding positions of the ink ribbon cassettes attached to the stocker 5-1 are stored in the RAM of the memory device 3 (S508). Then, the printing is carried out in accordance with the types and the holding places of the ink ribbon cassettes attached to the stocker 5-1 which have been stored in the RAM of the memory device 3 in S508 (S509). For example, there are four holding places, i.e., a holding place 1 (located in the left end) through a holding place 4 (located in the right end) in the stocker 5-1. When the color printing mode is selected in S501, it is identified based on the data stored in the memory device 3 (see Fig. 43) that the four types of the ink ribbon cassettes required for the selected printing mode are black, yellow, magenta and cyan ink ribbon cassettes respectively. It is assumed in S502 that (1) the cyan ink ribbon cassette is attached to the holding position 1, (2) the black ink ribbon cassette is attached to the holding position 2, (3) the magenta ink ribbon cassette is attached to the holding position 3 and (4) the blue ink ribbon cassette is attached to the holding position 4. In S503, since it is judged that the stocker 5-1 does not have the yellow ink ribbon cassette required for the printing. So, in S505 and S506, (1) "the blue ink ribbon cassette has been mistakenly attached to the stocker" and (2) "the yellow ink ribbon cassette should be attached to the holding position 4" are alarmed and informed to the user. The user attaches the yellow ink ribbon cassette to the holding position 4 in accordance with the foregoing alarming and informing. Thus, when it is judged that all the ink ribbon cassettes required for the printing are prepared, the holding states and the types of the ink ribbon cassettes in the stocker 5-1, i.e., the data that (1) the cyan ink ribbon cassette is attached to the holding position 1, (2) the black ink ribbon cassette is attached to the holding position 2, (3) the magenta ink ribbon cassette is attached to the holding position 3 and (4) the yellow ink ribbon cassette is attached to the holding position 4 are stored in the memory device 3 as illustrated in Fig. 46. The ink ribbon cassette changing of the changer 5-2 is carried out with reference to the data stored in the memory device 3. For instance, when the black ink ribbon cassette is required, the ink ribbon cassette in the holding position 2 is used. When the yellow ink ribbon cassette is required, the ink ribbon cassette in the holding position 4 is used. When the magenta ink ribbon cassette is required, the ink ribbon cassette in the holding position 3 is used. When the cyan ink ribbon cassette is required, the ink ribbon cassette in the holding position 1 is used. As mentioned above, after the holding states of the ink ribbon cassettes in the stocker are checked prior to the printing, the printing is appropriately carried out. With reference to Fig. 31, the following description deals with the case where it is judged on the carriage side whether or not the ink ribbon cassettes exist with the use of the stocker having no stocker cassette holding sensor. As illustrated in Fig. 31, the stocker cassette holding sensors 5-1-1 through 5-1-4, which were provided in the stocker 5-1, are not provided for judging the ink ribbon cassette holding state of the stocker, i.e., for detecting whether or not the ink ribbon cassette exists. Fig. 32 is a view illustrating the case where it is judged on the carriage side whether or not the ink ribbon cassettes exist and what the types of the ink ribbon cassette are with the use of the stocker having no stocker cassette type identification sensors. As illustrated in Fig. 32, instead of the sensor A (the stocker cassette type identification sensors 5-1-1-1 through 5-1-1-4), the sensor B (the stocker cassette type identification sensors 5-1-2-1 through 5-1-2-4) and the sensor C (the stocker cassette type identification sensors 5-1-3-1 through 5-1-3-4), there is provided a carriage cassette type identification sensor A (5-3-1-1), a carriage cassette type identification sensor B (5-3-1-2) and a carriage cassette type identification sensor C (5-3-1-3) for detecting what type of the ink ribbon cassette is held by the carriage 5-3. According to the combinations of the detected results of the carriage cassette type identification sensor A (5-3-1-1), the carriage cassette type identification sensor B (5-3-1-2) and the carriage cassette type identification sensor C (5-3-1-3), it is identified whether or not the ink ribbon cassette is held by the carriage 5-3 and what type (color) of the ink ribbon cassette is held. Figures 33(a) through 33(d) are explanatory views illustrating identification holes for identifying the types of the respective ink ribbon cassettes. As illustrated in Fig. 33(a), there are provided identification holes 7-1-1 through 7-1-3 on respective predetermined positions of the surface of an ink ribbon cassette 7-1 which comes into contact with the upper surface of the carriage. When the ink ribbon cassette 7-1 is held by the carriage 5-3 (see Fig. 33(b)), the carriage cassette type identification sensor A (5-3-1-1) is located in the identification hole 7-1-1, the carriage cassette type identification sensor B (5-3-1-2) is located in the identification hole 7-1-2 and the carriage cassette type identification sensor C (5-3-1-3 ) is located in the identification hole 7-1-3 respectively. Figures 33(c) and 33(d) are detail explanatory views illustrating the carriage cassette type identification sensor A (5-3-1-1), the carriage cassette type identification sensor B (5-3-1-2) and the carriage cassette type identification sensor C (5-3-1-3). The carriage cassette type identification sensor A (5-3-1-1), the carriage cassette type identification sensor B (5-3-1-2) and the carriage cassette type identification sensor C (5-3-1-3) respectively use the switches which change in to the on state when pushing down the respective projections. In case of Fig. 33(c), no ink ribbon is held by the stocker 5-1. Since no ink ribbon is held by the stocker 5-1, even when the stocker is moved down by the changer 5-2, the carriage cassette type identification sensor A (5-3-1-1), the carriage cassette type identification sensor B (5-3-1-2) and the carriage cassette type identification sensor C (5-3-1-3) are all into the off states. In contrast, as illustrate d in Fig. 33(d), when an ink ribbon cassette 7-2 having identification holes 7-2-1 and 7-2-3 is attached to the stocker 5-1 and the stocker 5-1 is moved down by the changer 5-2, the ink ribbon cassette 7-2 is held by the carriage 5-3, thereby resulting in that the carriage cassette type identification sensor A (5-3-1-1) and the carriage cassette type identification sensor C (5-3-1-3) become in the on states, while the carriage cassette type identification sensor B (5-3-1-2) becomes in the off state. Fig. 37 is an explanatory view illustrating the relation between the positions of the respective identification holes and the types of the respective ink ribbon cassettes. Thus, the holes for identifying the ink ribbon cassettes which are prepared in accordance with the types of the respective ink ribbon cassettes are detected by the carriage cassette type identification sensor A (5-3-1-1), the carriage cassette type identification sensor B (5-3-1-2) and the carriage cassette type identification sensor C (5-3-1-3). Then, it is judged whether or not the ink ribbon cassettes exist and what types of the ink ribbon cassettes are by the combinations of such detected results. Fig. 47 is a flow chart showing what procedures are made for judging on the carriage side whether or not the ink ribbon cassettes exist with the use of the stocker having no stocker cassette holding sensors. According to such procedures, it is confirmed whether or not the ink ribbon cassettes are attached to the stocker 5-1 prior to the printing operation as follows: (1) each attaching and detaching of the ink ribbon cassettes is carried out with respect to the position of the stocker 5-1 where each ink ribbon cassette is held, (2) the ink ribbon holding states in the respective holding positions of the stocker 5-1 are checked, i.e., whether or not the ink ribbon cassettes exist are checked by the carriage cassette holding sensor 5-3-1 of the carriage 5-3, thereby confirming the user that the types of the ink ribbon cassettes required for the selected printing mode and the holding positions to be held thereof. The required number and the types of the ink ribbon cassettes vary depending on the selected printing mode. So, the memory device 3 stores the data (appropriate ink ribbon cassette holding states) shown on Fig. 43 beforehand. Note that it not necessary for an ink ribbon cassette to be held in the position denoted as "arbitrary" in Fig. 43. Note also that either a "red", "green", or "blue" ink ribbon cassette may be held in the position denoted as "color". First, the printing mode is selected (S601). The stocker 5-1 is moved up by the changer 5-2 (S602). Then, a counter n is reset to zero (S603). The counter n is incremented by 1 (S605). The carriage 5-3 is moved under a holding position n of the stocker 5-1 (S605). Then, the stocker 5-1 is moved down by the changer 5-2 (S606). The ink ribbon cassette of the holding position n in the stocker 5-1 is attached to the carriage 5-3 (S607). It is detected by the carriage cassette holding sensor 5-3-1 of the carriage 5-3 whether or not the ink ribbon cassette exist in the holding position n of the stocker 5-1 (S 608). In S609, it is stored in the RAM of the memory device 3 whether or not the ink ribbon cassette exist in the holding position n of the stocker 5-1 (see Fig. 49). The ink ribbon cassette is taken out from the carriage 5-3 (S610). Thereafter, the ink ribbon cassette is returned to the stocker 5-1 and the stocker 5-1 is moved up (S611). According to the present embodiment, since there are four ink ribbon cassette holding positions in the sticker 5-1, it is checked whether or not the counter n is equal to four. If not so, S604 is carried out so that the counter n is incremented by 1. Thereafter, with respect to the next holding position of the stocker 5-1, it is similarly checked whether or not the ink ribbon cassette exists, and such checked result is stored. Thus, S604 through S611 are repeatedly carried out during n ≤ 4, i.e., are repeatedly carried out for the respective holding positions 1 through 4 of the stocker 5-1, thereby checking and storing the actual holding states (existence or non-existence) of the ink ribbon cassettes of the stocker 5-1. Fig. 49 shows one storing example of such holding states. The content of the stored holding states is effective until the stocker 5-1 is opened, i.e., until the stocker close sensor 5-1-5 changes into the off state. Next, (1) the actual holding states (existence or non-existence) of the ink ribbon cassettes of the stocker 5-1 obtained in accordance with the foregoing manner and (2) the holding states of the ink ribbon cassettes, which are stored in the memory device 3 as shown in Fig. 43, suitable for the selected printing mode are compared with each other (S613) . If the ink ribbon cassette is not attached to the holding position of the stocker where the ink ribbon cassette must be attached, the step proceeds from S614 to S615 so that the display device 4 alarms and informs the user that the ink ribbon cassette is mistakenly attached. When the user attaches the ink ribbon cassette to the appropriate holding position (S616), the process returns to S602 so as to check the ink ribbon cassette holding states of the stocker. In contrast, when (1) the actual holding states (existence or non-existence) of the ink ribbon cassettes of the stocker 5-1 obtained in accordance with the foregoing manner and (2) the holding states of the ink ribbon cassettes, which are stored in the memory device 3 as shown in Fig. 43, suitable for the selected printing mode (S613) are coincident with each other in S614, S617 is proceeded so that the display device 4 informs and confirms the user by displaying, as shown in Fig. 44, the types of the ink ribbon cassettes and the due positions thereof with reference to the ink ribbon cassette holding data (Fig. 43) stored in the memory device 3. Thereafter, S618 is proceeded so as to start the printing. According to the foregoing manner, it is judged on the carriage side whether or not the ink ribbon cassettes sexist with the use of the stocker having no stocker cassette holding sensor. Fig. 48 is a flow chart showing what procedures are made for judging on the carriage side of (1) the existence or non-existence of the ink ribbon cassettes and (2) the types thereof with the use of the stocker having no stocker cassette type identification sensor. According to such procedures, it is confirmed of existence and non-existence of the ink ribbon cassettes and the types thereof in the stocker 5-1 prior to the printing operation as follows: (1) each attaching and detaching of the ink ribbon cassettes is carried out with respect to the position of the stocker 5-1 where each ink ribbon cassette is held, (2) the ink ribbon cassette holding states (existence or non-existence and types) in the respective holding positions of the stocker 5-1, i.e., whether or not the ink ribbon cassettes exist are checked by the carriage cassette type identification sensor A (5-3-1-1), the carriage cassette type identification sensor B (5-3-1-2), and the carriage cassette type identification sensor C (5-3-1-3), and (3) it is checked in accordance with the holding states whether or not the types of the ink ribbon cassettes required for the selected printing mode are attached to the stocker 5-1. If so, the printing is appropriately carried out irrespective of the holding position of the stocker 5-1. First, the printing mode is selected (S701). The stocker 5-1 is moved up by the changer 5-2 (S702). Then, the counter n is reset to zero (S703). In S704, the counter n is incremented by 1. When the type of the ink ribbon cassette, held in the holding position n of the stocker 5-1, has been identified based on the fact that the types of the ink ribbon cassettes of the stocker 5-1 have once been checked for example (S705 and S706), it is recognized as unnecessary to judge the type of the ink ribbon cassette in the holding position n, thereby returning to S704 so that the counter n is further incremented by 1 and the type of the ink ribbon cassette is detected with respect to the next one in the stocker 5-1. Note that in the case where the types of the respective ink ribbon cassettes in the stocker 5-1 have been identified, since such types are stored in the RAM of the memory device 3 as shown in Figures 46 and 50, it is judged in accordance with the stored data whether or not the types have been identified. In contrast, when the type of the ink ribbon cassette, held in the holding position n of the stocker 5-1, has not yet been identified based on the fact that the types of the ink ribbon cassettes of the stocker 5-1 is checked for the first time for example (S705), the process advances to S706. In S706, it is detected by the stocker cassette holding sensors 5-1-1 through 5-1-4 whether or not the ink ribbon cassette is held in the holding position n of the stocker 5-1. If not, the process returns to S704 based on the judgement that no ink ribbon cassette exists in the holding position n of the stocker 5-1, thereafter the detection is carried out with respect to the next holding position of the stocker 5-1 by further incrementing the counter n by 1. In S706, when it is judged that the ink ribbon cassette is held in the holding position n, S707 is carried out accordingly. In S707, the carriage 5-3 is moved under the holding position n of the stocker 5-1. Then, the stocker 5-1 is moved down by the changer 5-2 (S708), and the ink ribbon cassette in the holding position n of the stocker 5-1 is attached to the carriage 5-3 (S709). In S710, it is detected, what type of the ink ribbon cassette is held in the holding position n of the stocker 5-1, by the carriage cassette type identification sensor A (5-3-1-1), the carriage cassette type identification sensor B (5-3-1-2) and the carriage cassette type identification sensor C (5-3-1-3) of the carriage 5-3. The detected type of the ink ribbon cassette in the holding position n is stored in the RAM of the memory device 3 as shown in Figures 46 and 50 (S711). Thereafter, the ink ribbon cassette is taken out from the carriage (S712), and the ink ribbon cassette is returned to the stocker 5-1 by the changer 5-2. In S713, the stocker 5-1 is moved up. According to the present embodiment, since there are provided four ink ribbon cassette holding positions in the stocker 5-1, it is checked in S714 whether or not the counter n is equal to four. If not counted, S704 is carried out again and the counter n is incremented by 1 so that the existence or non-existence of the ink ribbon cassettes is detected for the next holding position of stocker 5-1 and the detected result is stored in like the manner. Thus, S704 through S713 are repeatedly carried out during n ≤ 4, i.e., are repeatedly carried out for the respective holding positions 1 through 4 of the stocker 5-1, thereby checking and storing the actual holding states (existence or non-existence and types) of the respective ink ribbon cassettes of the stocker 5-1. Figures 46 and 50 show one storing example of such holding states. The content of the stored holding states is effective until the stocker 5-1 is opened so as to be taken out the ink ribbon cassette, i.e., until the stocker cassette holding sensors 5-1-1 through 5-1-4 change into the off state. Based on thus obtained results, it is checked whether or not all the types of the ink ribbon cassettes required for the printing mode selected in S701 are attached to the stocker 5-1 (S715). The ink ribbon cassettes required for the selected mode have been stored in the memory device 3 as shown in Fig. 43. In S716, it is judged whether or not the appropriate ink ribbon holding states are coincident with the actual holding states. Note that it is not necessary that the respective holding positions are coincident with each other but necessary that the number and types are coincident with each other. If one of the ink ribbon cassettes is not prepared, the process advances from S716 to S717. In S717, the device such as the display device 4 alarms and informs the user that there occurs error due to the ink ribbon cassette. The display device 4 alarms and informs that (1) the ink ribbon cassette required for the printing which is judged not to be attached to the stocker 5-1 in accordance with the checking of S715 and (2) the position to which the ink ribbon cassette must be attached (S718). After the user attaches the ink ribbon cassette in accordance with the alarming and informing of S717 and S718 (S719), S702 is carried out again so that it is checked whether or not all the types of the ink ribbon cassettes required for the printing are attached to the stocker 5-1. During the re-check, the checking with respect to the holding position, where the attaching and detaching of the ink ribbon cassette are not carried out in S719 because the types of the ink ribbon cassette has already been identified, is skipped in S705. Thus, when it is judged that all the types of the ink ribbon cassettes required for the printing are attached to the stocker 5-1 in S702 through S716, the types of the respective ink ribbon cassettes attached to the stocker 5-1 and the holding positions of the respective ink ribbon cassettes are stored in the RAM of the memory device 3 as shown in Figures 46 and 50 (S720). In S721, the desired printing is carried out in accordance with the types of the respective ink ribbon cassettes attached to the stocker 5-1 and the holding positions of the respective ink ribbon cassettes which are stored in S720. For example, since there are provided four holding positions, i.e., the holding position 1 (the left end) through the holding position 4 (the right end), when the color printing mode is selected in S701, it is judged based on the content (see Fig. 43) of the memory device 3 that the four types of the ink ribbon cassettes required for the color printing mode are black, yellow, magenta and cyan ink ribbon cassettes respectively. It is assumed that the cyan ink ribbon cassette is held in the holding position 1, the black ink ribbon cassette is held in the holding position 2, the magenta ink ribbon cassette is held in the holding position 3 and the blue ink ribbon cassette is held in the holding position 4 in S702 through S714. Since it is judged that the yellow ink ribbon cassette required for the printing lacks in S715, it is alarmed and informed to the user that "the blue ink ribbon cassette is mistakenly attached" and "the yellow ink ribbon cassette should be attached to the holding position 4. When it is confirmed, based on the fact that the user has attached the yellow ink ribbon cassette to the holding position 4, that all the ink ribbon cassettes required for the printing are prepared, the ink ribbon cassette holding states of the stocker 5-1 and types of the ink ribbon cassettes are respectively stored, i.e., the data that the cyan ink ribbon cassette is held in the holding position 1, the black ink ribbon cassette is held in the holding position 2, the magenta ink ribbon cassette is held in the holding position 3 and the yellow ink ribbon cassette is held in the holding position 4 are stored in the memory device 3 as shown in Fig . 46. The changer 5-2 changes the ink ribbon cassette in reference to such stored data. More specifically, when the black ink ribbon cassette is required, the ink ribbon cassette attached to the holding position 2 is used. When the yellow ink ribbon cassette is required, the ink ribbon cassette attached to the holding position 4 is used. When the magenta ink ribbon cassette is required, the ink ribbon cassette attached to the holding position 3 is used. When the cyan ink ribbon cassette is required, the ink ribbon cassette attached to the holding position 1 is used. It is judged on the carriage side in accordance with the foregoing manner (1) whether or not the ink ribbon cassettes exist and (2) what types of the respective ink ribbon cassettes are attached with the use of the stocker having no stocker cassette type identification sensor. [FOURTH EMBODIMENT] The following descriptions will discuss the fourth embodiment of the present invention in reference to Fig. 51 through Fig. 60. However, it should be noted here that the present invention is not limited to this preferred embodiment. The present embodiment will be explained through the example of the ink ribbon cassette-automatic changer printing system which permits a printing operation by automatically exchanging among four ink ribbon cassettes. The basic configuration of the system of the present invention is the same as that of the first embodiment with some exemptions. Therefore, for convenience in explanations, members having the same function as the aforementioned preferred embodiment will be designated by the same reference numerals, and thus the descriptions thereof shall be omitted here. Fig. 51 is a table which summarizes the relationship among the output state of the changer upper limit sensor 5-2-2 and the changer lower limit sensor 5-2-3 (see Fig. 9 in the first embodiment), and an angle of the cam 5-2-1 and the height position of the stocker. For example, when the changer upper limit sensor 5-2-2 is set ON, and the changer lower limit sensor 5-2-3 is set OFF, it can be seen that the angle of the cam 5-2-1 is 0°, and the stocker 5-1 is set in the upper limit position. In the present embodiment, a carriage left limit sensor (not shown) is provided. The carriage left limit sensor is turned ON when the carriage 5-3 is moved to the left limit position, and using this position as an original position, the carriage left limit sensor recognizes the current position of the carriage 5-3 by the moving distance from the original position. (The motor for driving the carriage 5-3 can recognizes the moving distance by the number of steps of the stepping motor is provided). Here, in order to move the carriage 5-3 right below each of the ink ribbon cassettes 5-5 through 5-8, the number of steps (from the original position to the position of each stocker) to be applied to the stepping motor (not shown) for moving the carriage 5-3 is stored in the memory device 3 beforehand. Then, the value obtained by subtracting the number of steps in the current position of the carriage from the number of steps in the target position of the stocker is applied to the stepping motor. When the changer 5-2 raises or lowers the stocker 5-1, whether or not the stocker movable holding claw (see Fig. 15 in the first embodiment) can be selected by the claw moving cam (not shown) which raises and lowers the stocker 5-1. Like the cam 5-2-1 (see Fig. 9 in the first embodiment), the claw moving cam rotates in synchronous with the operation of the changer. The claw moving cam has a projection formed at a position between 180 ° (the stocker 5-1 is at the bottom end) and 270 ° (the stocker 5-1 is at the intermediate position) for moving the stocker movable holding claw. Namely, when the stocker 5-1 is raised by rotating the changer motor (not shown) in the direction of 180° → 270° → 360° (0°), the stocker movable holding claw 5-1-8 is moved. On the other hand, when the stocker 5-1 is raised by rotating the changer motor in the direction of 180° → 90° → 0°, the stocker movable holding claw 5-1-8 is not moved. Fig. 52(a) and Fig. 52(b) are explanatory view showing the cross section of the ink ribbon cassette automatic changer printer in accordance with the present invention. Fig. 52(a) shows the state where the stocker 5-1 is raised to the upper limit position, while Fig. 52(b) shows the state where the stocker 5-1 is lowered to the lower limit position. In Fig. 52(a) and Fig. 52(b), the print sheet 5-4-3 is fed by the sheet feeding roller 5-4-2 in the direction of an arrow in the figures to be placed between a platen 5-10 and the print head 5-3-2. When the print sheet 5-4-3 is inserted, the output from the sheet detecting sensor 5-4-1 is set ON so as to indicate that the sheet is inserted. For the sheet detecting sensor 5-4-1, the same switch as the carriage cassette detecting sensor 5-3-1 is used (the switch is turned ON only when the projection is pushed, and the projection is pushed by the insertion of the sheet, and the output is set ON. In Fig. 52(a), the stocker 5-1 is placed in the upper limit position. However, in this state, when the print sheet 5-4-3 is transported, the leading end portion of the print sheet 5-4-3 is brought in contact with the bottom end portion of the stocker 5-1, which causes sheet jam. In Fig. 52(b), the stocker 5-1 is placed at the lower limit position. In this state, the print sheet 5-4-3 is not in contact with the lower limit position of the stocker 5-1, and is smoothly transported while being guided by the front surface portion of the stocker 5-1. Fig. 53 is a flowchart showing process for preventing the carriage from moving when the changer is not in the carriage movable state. In the present embodiment, in order to pass the ink ribbon cassette between the stocker 5-1 and the carriage 5-3, the changer 5-2 moves the stocker 5-2 up and down. However, even if the carriage 5-3 is tried to be moved when the stocker 5-1 is not raised, the carriage 5-3 is in contact with the stocker 5-1, and the carriage 5-3 cannot be moved, which causes a trouble. in this process, it is controlled such that the carriage 5-3 is not moved when the stocker is not placed in the upper limit position. When an instruction for moving the carriage 5-3 is given, the process shown in the flowchart of Fig. 53 is started. First, in S801, it is determined whether the changer upper limit sensor 5-2-2 is set in the ON position or the OFF position. If the changer upper limit sensor 5-2-2 is set in the ON position, the sequence goes to S802, while, if the changer upper limit sensor 5-2-2 is set in the OFF position, the sequence goes onto S803. In S802, it is determined whether the changer lower limit sensor 5-2-3 is set in the ON position or in the OFF position. If the changer lower limit sensor 5-2-3 is set in the ON position, the sequence goes to S803, while, if the changer upper limit sensor 5-2-2 is set in the OFF position, the sequence goes to S804. In S803, since the changer upper limit sensor 5-2-2 is in the OFF position or the changer upper limit sensor 5-2-2 is set in the ON position and the changer lower limit sensor 5-2-3 is in the ON position, as can be seen from Fig. 51, the stocker is not in the upper limit position, and the carriage 5-3 cannot be moved. Therefore, the stocker 5-1 is moved by the carriage 5-3, and the sequence goes onto S804. On the other hand, in S804, since the changer upper limit sensor 5-2-2 is set ON, and the changer lower limit sensor 5-2-3 is set OFF, it can be seen that the stocker 5-1 is in the upper limit position as is clear from Fig. 51, and the carriage 5-3 is moved, thereby terminating the process. By the described process, when the changer is not set in the carriage movable position, the movement of the carriage is stopped. Fig. 24 is a flowchart showing the content of the process for stopping the operation of the changer when the changer is not set in the desired state. In the present embodiment, when the ink ribbon cassette is passed between the stocker 5-1 and the carriage 5-3, the changer 5-2 moves the stocker 5-1 up and down. However, when the stocker 5-1 cannot be moved for some reason (for example, the carriage 5-3 is moved by the user or a object is placed on the stocker 5-1), a load is incurred on the changer motor, etc., which may result in some trouble. Therefore, in this process, it is controlled such that if a desirable state of the changer 5-2 cannot be achieved even after a predetermined time has elapsed, the operation of the changer 5-2 would be stopped. The predetermined time is set to an optimal value according to the specification of the ink ribbon cassette automatic changer printer (larger enough than the time required for a normal operation and smaller enough than the time which creates the problem such as an overheat of the motor) to be stored in the memory device 3. When an instruction is given for operating the changer 5-2, the process shown in the flowchart of Fig. 54 is started. First, in S811, the timer is reset for measuring the time. The timer is provided in the arithmetic and control unit 1. In S812, the operation of the changer 5-2 (for raising or lowering the stocker 5-1) is initiated. In S813, it is determined whether or not the operation of the changer 5-2 is completed by the changer upper limit sensor 5-2-2 and the changer lower limit sensor 5-2-3. If so, the process is terminated, and if not the sequence goes onto S814. In the case where the changer 5-2 is operated so as to raise the stocker 5-1, when the changer upper limit sensor 5-2-2 is set in the ON position, and the changer lower limit sensor is set in the OFF position, it is determined that the process is completed. On the other hand, in the case where the changer 5-2 is operated so as to lower the stocker 5-1, when the changer upper limit sensor 5-2-2 is set in the OFF position, and the changer lower limit sensor is set in the ON position, it is determined that the process is completed. In S814, it is determined whether or not a predetermined time has elapsed after the operation of the changer 5-2 is started based on the timer in the arithmetic control unit 1 and the time set in the memory unit 3. If the predetermined times has not elapsed, the sequence goes back to S813, and if elapsed, the sequence moves onto S815. In S815, since the operation of the changer 5-2 is not completed although the predetermined time has elapsed, it is determined that an abnormality has occurred in the ink ribbon cassette automatic changer printer. Then, a message such as "Abnormality has occurred in the printer. Switch off the power supply." is displayed on the display unit 4 so as to inform the user of the occurrence of abnormality, thereby terminating the process in accordance with the present embodiment. By the displayed message, the user can see the occurrence of the abnormality in the printer, and if an object is placed on the stocker, it is to be removed, and the power switch is turned off. On the other hand, if the power supply is turned on again, the system initializes the printer. In this state, if the problem of the abnormality condition is solved, the printing operation is performed again in the normal process. By the process for managing the abnormality condition, if the changer is not set in the desired state, the operation of the changer is stopped. Fig. 55 is a flowchart showing the content in the process for automatically switching the changer from the carriage movable state to the ribbon exchange state. In this process, in order to ease the insertion of print sheet by the user in the ink ribbon cassette automatic changer printer (in order to prevent the occurrence of sheet jamming), or in order to lower the height of the member for storing the ink ribbon cassette automatic changer printer, it is controlled so that the stocker 5-1 is lowered after the printing operation is completed. When the printing operation of the ink ribbon cassette automatic changer printer is started, the process shown in the flowchart of Fig. 55 is started. First, in step S822, the printing process is performed. In S822, it is determined whether or not the printing operation is terminated. If not, the sequence goes back to S821, if so the sequence moves onto S823. In S823, it is determined whether or not the ink ribbon cassette is held on the carriage 5-3. If so, the sequence moves onto S827, and if not the sequence moves to S824. In S824, in order to set the ink ribbon cassette on the carriage 5-3 back to the initial position of the stocker 5-1, the carriage 5-3 is moved to the position right below the holding position corresponding to the stocker 5-1. In S825, the changer 5-2 lowers the stocker 5-1. As a result, the ink ribbon cassette on the carriage 5-3 is supported by both the carriage 5-3 and the stocker 5-1. In S826, the changer 5-2 raises the stocker 5-1 (holding the ink ribbon cassette) without moving the stocker movable holding claw 5-1-8. By the described process in S824 through S826, the ink ribbon cassette is passed to the stocker 5-1 on the carriage 5-3. Next, in S827, the carriage 5-3 is moved to the home position. In the conventional printer, the home position of the carriage 5-3 is set in the central position as disclosed by Japanese Laid-Open Patent Application No. 2582767/1990 (Tokukaihei 2-2582767), in order to smoothly transport the print sheet. On the other hand, in the present invention, it is arranged so as to smoothly transport the print sheet by setting the stocker in the lower position 5-1 as will be described later. Therefore, the home position of the carriage 5-3 is not limited. For example, in the present embodiment, the home position is set to the left end position of the stocker 5-1 for storing the black ink ribbon cassette which is usually used most often. However, the home position may be set to an other position. In S828, the changer 5-2 does not lower the stocker movable holding claw 5-1-8 but lowers the stocker 5-1 (holding the ink ribbon cassette). By the described process, after performing the printing operation, the position of the changer is automatically switched from the carriage movable state to the ribbon exchange state. The processes in S824 and S827 are the processes for moving the carriage 5-3. Therefore, if the changer is not in the carriage movable state, it is also controlled so as to prevent the carriage from moving. The processes in S825, S826 and S828 are to be performed by the changer 5-2 (for moving the stocker 5-1 up and down). Therefore, it is also controlled such that if the changer is not set in the desired state, the operation of the changer is stopped. Fig. 58 is a flowchart showing the process for automatically switching the position of the changer from the carriage movable state to the ribbon exchange state upon turning ON the power switch. This process is performed for controlling such that if the stocker 5-1 is in a lower position (due to the interruption of the power source, etc.), the stocker 5-1 is further lowered so as to ease the user to insert the print sheet to the ink ribbon cassette automatic changer printer (to prevent the sheet jamming) or to lower the height of the member for storing the ink ribbon cassette automatic changer printer. When the power switch of the ink ribbon cassette automatic changer printer system is turned ON, the operation shown in the flowchart of Fig. 56 is started. First, in S831, it is determined whether the changer upper limit sensor 5-2-2 is set in the ON position or in the OFF position. If the changer upper limit sensor 5-2-2 is set in the ON position, the sequence moves to S832, and if it is set in the OFF position, the sequence moves to S833. In S832, it is determined whether the changer lower limit sensor 5-2-3 is set in the ON position or in the OFF position. If the changer lower limit sensor 5-2-3 is set in the ON position, the sequence moves to S834, and if it is in the OFF position, since the changer upper limit sensor 5-2-2 is in the ON position and the changer lower limit sensor 5-2-3 is in the OFF position, as can be seen from Fig. 7, it is determined that the stocker 5-1 is in the upper limit position. Then, the sequence moves to S835. In S833, it is determined whether the changer lower limit sensor 5-2-3 is in the ON position or in the OFF position. If it is in the ON position, since the changer upper limit sensor 5-2-2 is in the OFF position, and the changer lower limit sensor 5-2-3 is in the ON position, as can be seen from Fig. 7, the stocker 5-1 is in the lower limit position. Therefore, it is determined that the power source before turning the power switch ON is properly interrupted (the power switch is turned OFF when the printing operation is not performed), thereby terminating this process. On the other hand, if the changer lower limit sensor 5-2-3 is in the OFF position, the sequence moves to S834. In S834, both the changer upper limit sensor 5-2-2 and the changer lower limit sensor 5-2-3 are in the ON position, or both the changer upper limit sensor 5-2-2 and the changer lower limit sensor 5-2-3 are in the OFF position. Therefore, as can be seen from Fig. 7, since the stocker 5-1 is in the intermediate position, the changer 5-2 once lowers the stocker 5-1, and after placing the ink ribbon cassette on the carriage 5-3, the changer 5-2 raises the stocker 5-1. Then, the sequence moves to S835. In S835, since the stocker 5-1 is raised to the upper limit position, and the carriage 5-3 can be moved, the carriage 5-3 is moved to the home position. This is because by moving the carriage 5-3 to the home position (the position where the black ink ribbon cassette which is usually used most often is stored), the process for initiating the printing operation can be performed efficiently. Lastly, in S836, the changer 5-2 lowers the stocker 5-1, and this process is terminated. By the described process, the position of the changer can be automatically switched from the carriage movable state to the ribbon exchange state upon turning ON the power switch. Fig. 57 is a flowchart showing the process for preventing the stocker from being raised until the print sheet is inserted. This process is performed for controlling the stocker 5-1 so as not to be raised until the insertion of the print sheet is confirmed in order to ease the user to insert the print sheet in the ink ribbon cassette automatic changer printer when initiating the printing operation (in order to prevent the occurrence of sheet jamming). When the user gives an instruction for starting the printing operation in the ink ribbon cassette automatic changer printer system, or an additional sheet is required when the sheet is run out during the printing operation, the process in the flowchart of Fig. 57 is started. First, in S841, it is determined whether or not the print sheet is inserted by the sheet detecting sensor 5-4-1. If the sheet is not inserted, the sequence moves to S842. On the other hand, if the sheet is inserted, the sequence moves to S849. In S842, it is determined whether or not the changer upper limit sensor 5-2-2 is in the ON position or in the OFF position. If it is in the ON position, the sequence moves to S843, and if it is in the OFF position, the sequence moves to S844. In S843, it is determined whether or not the changer lower limit sensor 5-2-3 is in the ON position or in the OFF position. If the changer lower limit sensor 5-2-3 is in the ON position, the sequence goes to S845. On the other hand, if the changer lower limit sensor 5-2-3 is in the OFF position, since the changer upper limit sensor 5-2-2 is in the ON position, and the changer lower limit sensor 5-2-3 is in the OFF position, as can be seen from Fig. 51, it is determined that the stocker 5-1 is in the upper limit position, and the sequence moves to S846. In S844, it is determined whether or not the changer lower limit sensor 5-2-3 is in the ON position or in the OFF position. If the changer lower limit sensor 5-2-3 is in the ON position, since the changer upper limit sensor 5-2-2 is in the OFF position, and the changer lower limit sensor 5-2-3 is in the ON position, as can be seen from Fig. 7, it is determined that the stocker 5-1 is in the lower limit position, and the sequence goes to S843. On the other hand, if the changer lower limit sensor 5-2-3 is in the OFF position, the sequence goes to S845. In S845, both the changer upper limit sensor 5-2-5 and the changer lower limit sensor 4-2-3 are set in the ON position, or both the changer upper limit sensor 5-2-2 and the changer lower limit sensor 5-2-3 are set in the OFF position. Therefore, as can be seen from Fig. 7, since the stocker 5-1 is in an intermediate position, the changer 5-2 once lowers the stocker 5-1, and the stocker 5-1 holds thereon the ink ribbon cassette on the carriage 5-3, the changer 5-2 raises the stocker 5-1. In S846, since the stocker 5-1 is set on the upper limit position, and the carriage 5-3 can be moved, the carriage 5-2 is moved to the home position. When the kind (color) of the ink ribbon cassette to be used is known, (for example, in the case where the sheet is run out during the printing operation), it may be arranged such that the carriage 5-2 is moved right below the position in the stocker, where the ink ribbon cassette to be used is held. As a result, the time required for starting the printing operation can be shortened. In S847, the changer 5-2 lowers the stocker 5-1, and the sequence moves to S848. In S848, a message such as "set a print sheet in the printer", etc., is displayed on the display device 4 for urging the user to insert the print sheet. Then, the sequence moves to S841. Although it is not adopted in the present embodiment, if the insertion of the sheet is confirmed in S841, the printing operation is started in S849, and this process is terminated. The described process is performed so as to prevent the stocker from being raised until the print sheet is inserted. Fig. 58 is a flowchart showing the process for determining whether or not the stocker is to be raised with the ink ribbon cassette being held thereon when raising the position of the stocker at the start of the printing operation. The flowchart of Fig. 58 also shows the process for recognizing the kind of the ink ribbon cassette on the carriage based on the storing state of the ink ribbon cassette in the stocker in the case, that is to be performed when the kind of the ink ribbon cassette on the carriage cannot be recognized. The described process is performed for controlling so as to determine whether the changer 5-2 raises the stocker 5-1 with the ink ribbon cassette held thereon or in the open state at the start of the printing operation, in order to reduce the time required for stating the printing operation. When the kind of the ink ribbon cassette on the carriage cannot be recognized by the general method (for example, when the position of the carriage cannot be recognized immediately after the power switch is turned ON, or the ink ribbon cassette is already set on the carriage upon turning ON the power switch), the kind of the ink ribbon cassette on the carriage is recognized from the holding state of the ink ribbon cassette in the stocker. When the user gives an instruction for starting the printing operation in the ink ribbon cassette automatic changer printer system, the process in the flowchart of Fig. 58 is started. The example will be given through the following case. The print sheet is already inserted in the printer, the stocker 5-1 is in the lower state, and four ink ribbon cassettes are stored in the stocker 5-1 in the order of B, Y, M and C (black, yellow, magenta and cyan) from the left end. The described state is stored in the memory 3 as shown in Fig. 59. In Fig. 58, the kind (color) of the ink ribbon cassette to be used first when starting the printing operation in 901 is recognized (black, when the color is not specified in the print data) in reference to the print data stored in the memory device 3. In S902, it is determined whether or not the current position of the carriage 5-3 is known. If the current position of the carriage 5-3 is known, the sequence moves to S903. If not, the sequence moves to S610. The position of the carriage 5-3 is recognized in the following manner. A carriage left limit position sensor (not shown) is provided. The carriage left limit position sensor is set in the ON position when the carriage 5-3 is moved to the left limit position. The position of the carriage 5-3 is recognized by the distance the carriage 5-3 moves from the described position (original position). Therefore, for example, when the printer is not initialized after turning ON the power switch (the carriage 5-3 is not moved to the original position), the current position of the carriage 5-3 cannot be recognized. In S903, as the position of the carriage 5-3 is known, the kind of the ink ribbon cassette held on the carriage 5-3 is recognized based on the position of the carriage 5-3. (Since the order off storing the ink ribbon cassettes in the stocker 5-1 is stored in the memory device 3 as shown in Fig. 59, i.e., the storing order of four ink ribbon cassettes B, Y, M and C from the left end in the stocker 5-1, for example, when the stocker 5-1 is moved to the left limit position of the carriage 5-3, it can be seen that the black ink ribbon cassette is held on the carriage 5-3 from Fig. 59. In S903, it is determined whether or not the kind (color) of the ink ribbon cassette held on the carriage 5-3 recognized in S903 is identical with the kind (color) of the ink ribbon cassette to be used when starting the printing operation. If so, the sequence moves to S908, and if not the sequence moves to S905. In S905, since the ink ribbon cassette held on the carriage 5-3 will not be used when starting the printing operation, the changer 5-2 raises the stocker 5-1 with the ink ribbon cassette held thereon. In S906, the carriage 5-3 is moved to the position right below the position where the ink ribbon cassette to be used first when starting the printing operation, that is recognized in S901 is held. (For example, when the kind (color) of the ink ribbon cassette recognized in S901 is cyan, it can be seen from Fig. 59 that the carriage 5-1 is moved to the right limit position). In S907, the changer 5-2 lowers the stocker 5-1. In S908, the changer 5-2 raises the normal recording area 5-1 with the ink ribbon cassette remaining in the carriage 5-3. In S909, since the ink ribbon cassette to be used first when starting the printing operation, which is recognized in S901 is held on the carriage 6-3, the printing operation is started using the cassette, thereby terminating this process. On the other hand, if it is determined in S902 that the current position of the carriage 5-3 is not known, the sequence moves to S610. In S610, the ink ribbon cassette holding position of the stocker 5-1 is detected by the stocker cassette holding sensors 5-1-1 through 5-1-4 to be stored in the memory device 3. (In this example, four ink ribbon cassettes are stored in the stocker 5-1 in the order of B, Y, M and C from the left end, and thus the storing state is stored in the memory 3 as shown in Fig. 60(a).) 60(a)). In S611, the changer 5-2 raises the stocker 5-1 with the ink ribbon cassette remaining on the carriage 5-3. In S612, the ink ribbon cassette holding state of the stocker 5-1 is detected again by the stocker cassette holding sensors 5-1-1 through 5-1-4, to be compared with the state stored in S610. As a result of comparison, it is recognized such that the ink ribbon cassette corresponding to the position subject to a change from "exist" to "not exist" is the ink ribbon cassette held on the carriage 5-3. In the case where the content of the memory in S610 is as shown in Fig. 60(a), and the result of detection in S612 is as shown in Fig. 60(b), as a change occurs at the left end position, from the content stored in the memory 3 as shown in Fig. 59, it is recognized that the black ink ribbon cassette is held on the carriage 5-3. In the case where three ink ribbon cassettes are stored on the stocker 5-1, and a single ink ribbon cassette is held on the carriage 5-3, the kind (color) of the ink ribbon cassette held on the carriage 5-3 can be recognized from the position of the empty space in the stocker 5-1, where the ink ribbon cassette is not held. In the case where a single ink ribbon cassette is held on the carriage 5-3, and the stocker 5-1 is set in the state shown in Fig. 60(b), it can be recognized that the black ink ribbon cassette is held on the carriage 5-3 without comparing the state with the state shown in Fig. 60(a). In S613, it is determined whether or not the kind (color) of the ink ribbon cassette held on the carriage 5-3 that is recognized in S612 is identical with the kind (color) of the ink ribbon cassette to be used first when starting the printing operation that is recognized in S901. If they are identical, the sequence moves to S909, and if not, the sequence moves to S614, In S614, the changer 5-2 lowers the stocker 5-1, and the sequence moves to S905. Then, the same processes as described earlier are performed. In the case of adopting the system which is nor provided with the stocker cassette holding sensors 5-1-1 through 5-1-4, if it is determined that the position of the carriage 5-3 is not known in S902, the sequence may skip to S905. Even in the case of adopting the system provided with the stocker cassette holding sensors 5-1-1 through 5-1-4, the process for transiting to S610 is effective (the process for reducing the time required for starting the printing operation) only when the kind (color) of the ink ribbon cassette held on the carriage 5-3 is identical with the kind (color) of the ink ribbon cassette to be used first that is recognized in S901. Therefore, when there is a high possibility that they are different (for example, when the recognized color is other than "black" in S901), it is better to move to S905. By the described process, when raising the stocker at the start of the printing operation, it is determined whether or not the ink ribbon cassette is to be raised with the ink ribbon cassette held therein. If the kind of the ink ribbon cassette on the carriage cannot be recognized, the kind of the ink ribbon cassette on the carriage is recognized from the storing state of the ink ribbon cassette in the stocker. The invention being thus described, it will be obvious that the same way may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims: A printer system with an ink ribbon cassette automatic exchange function, comprising: a carriage (5-3) having a thermal head, said carriage (5-3) being movable while holding the ink ribbon cassette; a stocker (5-1) for detachably storing a number of cassettes; a changer (5-2) for moving said carriage (5-3) and said stocker (5-1) between (1) a ribbon delivery state in which said carriage (5-3) and said stocker (5-1) come closer with each other so as to deliver the ink ribbon cassette therebetween and (2) a carriage movable state in which said carriage (5-3) and said stocker (5-1) are away from each other so that said carriage (5-3) becomes movable, characterized by said carriage (5-3) including both the ink ribbon cassette and the thermal head; said carriage (5-3) having cassette detection means for detecting if the ink ribbon cassette is stored; said stocker (5-1) having storage detection means (5-1-1 to 5-1-4) for detecting if each ink ribbon cassette (5-5 to 5-8) is stored; and cassette removing means for removing the ink ribbon cassette held on the carriage (5-3) by operating the changer (5-2) when a print mode for printing on a thermosensitive sheet is selected; said cassette removing means removes the ink ribbon cassette when said ink ribbon cassette is held on said carriage based on a result of detection by said cassette detection means; and said cassette removing means moves the ink ribbon cassette as removed from the carriage (5-3) to a position of the stocker (5-1) where the ink ribbon cassette is not held based on a result of detection of said storage detection means (5-1-1 to 5-1-4). A printer system according to claim 1, comprising: ink ribbon cassette judging means (1.) for detecting holding states of the respective ink ribbon cassettes of said stocker (5-1) before and after the movement of said changer (5-2), (2.) checking whether or not the holding states of the respective ink ribbon cassettes after the movement of said changer (5-2) are coincident with target holding states to be after the movement of said changer (5-2), and (3.) for carrying out error procedures when said both holding states are not coincident with each other. A printer system according to claim 1, comprising: ink ribbon cassette holding state informing means (1.) for detecting holding states of the respective ink ribbon cassettes of said stocker (5-1) prior to printing, (2.) for judging whether or not the detected holding states are suitable for a printing mode to be printed, and (3.) for informing of suitable holding states of the ink ribbon cassette. A printer system according to claim 1, comprising: changer movement cassette detection means for detecting holding states of the respective ink ribbon cassettes of said stocker (5-1) based on the fact that said cassette detection means of said carriage (5-3) detects the ink ribbon cassettes during the ink ribbon cassette delivery of said changer (5-2). A printer system according to claim 1, comprising: a carriage (5-3), having a printing head and carriage ribbon type identifying means for identifying type of the ink ribbon cassette held by said carriage (5-3), said carriage (5-3) being movable while holding the ink ribbon cassette, a stocker (5-1) for holding the ink ribbon cassettes, the respective ink ribbon cassettes being detachable from said stocker, changer movement cassette detection means for detecting the types of the respective ink ribbon cassettes of said stocker (5-1) based on the fact that said carriage ribbon type identifying means identifies the ribbon type of the ink ribbon cassette held by said carriage (5-3) during the ink ribbon cassette delivery of said changer (5-2).

Inventors: OGAWA TATSUYA, SHIMIZU YUKIO, TAKATANI HIROSHI, WATANABE TADASHI, OGAWA, TATSUYA, SHIMIZU, YUKIO, TAKATANI, HIROSHI, WATANABE, TADASHI
Applicants: SHARP KK, SHARP KABUSHIKI KAISHA
Application year: 1995
Main classification: B41J35
IPC codes: B41J35, B41J17, B41J33