Abstract:
In an inkjet printer having at least one interchangeable container ( 16 ) for printing ink, having a holder ( 10 ) to hold the interchangeable container ( 16 ), having a switching device to block and enable the inkjet printer, having a signal transmitter ( 24 ) and a signal receiver ( 28 ) connected to the switching device, which are arranged on the holder ( 10 ), and having a signal transmitting device, on the interchangeable container ( 16 ), which transmits an enable signal from the signal transmitter ( 24 ) to the signal receiver ( 28 ) during or after the insertion of the interchangeable container ( 16 ) into the holder, the signal transmitting device is arranged in the interior of the interchangeable container ( 16 ) and has a signal input ( 38 ), a signal transmission element ( 40 ) and a signal output ( 48 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is entitled to the benefit of and incorporates by reference essential subject matter disclosed in International Patent Application No. PCT/DE99/02289 filed on Jul. 26, 1999 and German Patent Application No. 19839225.7 filed on Aug. 28, 1998. 
     FIELD OF THE INVENTION 
     The invention relates to a matrix printer using interchangeable ink container and having a means for preventing operation of the printer with an improper ink container. 
     BACKGROUND OF THE INVENTION 
     A matrix printer of this type, designed as an inkjet printer, is disclosed by the document EP 0 606 047 A2. Its print head has a relatively small supply volume for ink, which is connected via a flexible connecting line to an interchangeable container which contains a larger ink supply. The printing ink is led out of the interchangeable container, through the connecting line, into the supply volume of the print head. As a result, the inkjet printer can carry out print jobs with very high ink consumption without the printing operation being interrupted to refill the supply volume or to replace the print head. 
     Although the known inkjet printer starts a printing operation even when no interchangeable container is connected to the supply volume in the print head, in this case there is the risk that particularly long print jobs will be carried out only incompletely and/or erroneously and will therefore have to be repeated. 
     U.S. Pat. No. 5,506,611 describes an inkjet printer and an interchangeable ink container that can be operated therein. In order to verify the proper arrangement of the ink container inside a holder belonging to the printer, inter alia a reporting system is proposed which is constructed as follows: provided on the printer is a shaft-like holder, into whose clear space a projection projects. Provided on the upper side of the ink container is an opening which is closed by a displaceable cover. When the ink container is inserted into the holder, the cover is held back by the projection, so that the opening in the upper side of the ink container is opened as the ink container is inserted further into the holder. This releases the pivoting path of a flag which, being driven by a spring, swings out of the ink container and penetrates into a forked light barrier. The latter reports the presence of an ink container in the printer to a printer control system. 
     A further drawback is that an interchangeable container with ink unsuitable for the operation of the inkjet printer can also be inserted into the holder, and makes the print head unserviceable or damages it permanently. 
     DE 91 16 990 U1 has therefore proposed to apply to the surface of an ink container a pattern of lines which connects two contacts arranged on a container holder when the ink container is put correctly into the container holder. The making of contact is reported to a control unit, which for its part enables the printing operation. In the case of this arrangement, it is also disadvantageous that, by means of the improper connection of the contacts, it is possible to feign a proper ink container which, however, contains an ink which is unsuitable for the printer. On the other hand, in the event of relatively long use of one and the same ink container, oxidation of the pattern of lines and of the contacts can occur. 
     U.S. Pat. No. 5,506,611 describes an inkjet printer and an interchangeable ink container that can be operated therein. In order to verify the proper arrangement of the ink container inside a holder belonging to the printer, inter alia a reporting system is proposed which is constructed as follows: provided on the printer is a shaft-like holder, into whose clear space a projection projects. Provided on the upper side of the ink container is an opening which is closed by a displaceable cover. When the ink container is inserted into the holder, the cover is held back by the projection, so that the opening in the upper side of the ink container is opened as the ink container is inserted further into the holder. This releases the pivoting path of a flag which, being driven by a spring, swings out of the ink container and penetrates into a forked light barrier. The latter reports the presence of an ink container in the printer to a printer control system. 
     It is the object of the invention to configure a matrix printer of the type mentioned at the beginning, and an interchangeable container for printing ink to be used with said printer, in such a way that the printing operation can be enabled or blocked reliably if no interchangeable container, or an unsuitable one, is inserted into the holder. 
     SUMMARY OF THE INVENTION 
     This object is achieved by a matrix printer having the features of claim  1 . Advantageous developments of the invention are specified in the dependent claims. 
     In order to block and enable the printing operation, the matrix printer according to the invention has a signal transmitter and a signal receiver, which are formed on the holder, and also a signal transmitting device which is arranged on the interchangeable container. The receipt of an enable signal, emitted by the signal transmitter, by the signal receiver is interrupted as long as the interchangeable container having the signal transmitting device is not inserted into the holder. The printing operation remains blocked and is enabled only when the signal transmitting device of the interchangeable container, when the container is inserted completely into the holder, passes on the enable signal to the signal receiver. 
     The invention therefore firstly ensures that the printing operation is enabled only when an interchangeable container having the above-described equipment is inserted into the holder. Secondly, an interchangeable container without the signal transmitting device cannot be operated with the matrix printer. In this way, the matrix printer is therefore simultaneously protected against the use of an interchangeable container with unsuitable printing ink, which does not have the signal transmitting device. 
     There is interaction between a signal input, a signal transmitting device and a signal output. The arrangement of signal input and signal output is made in such a way that the enable signal can be transmitted from the signal transmitter to the signal receiver on the holder. This arrangement makes the signal transmitting device particularly robust against external influences. In addition, the inkjet printer and the interchangeable container, as a result of the precisely defined mutual arrangement of signal transmitter and signal input, on the one hand, and signal output and signal receiver, on the other hand, and also a corresponding arrangement and configuration of the signal transmission element, bear additional features which protect against the use of unsuitable interchangeable containers. 
     It is advantageous that the signal transmitting device in the interchangeable container is mounted separately from the ink supply. As a result, it is protected against possible damaging effects of the printing ink, and otherwise necessary devices for sealing the interchangeable container at the signal input and at the signal output are dispensed with. 
     The use and transmission of a mechanical enable signal provides a particularly simple and robust embodiment of the inkjet printer and of the interchangeable container. In this connection, a mechanical signal is understood to mean a symbol transmitted by the transport of movement energy or potential energy in a system of coupled mechanical components and having a specific significance. The signal transmitter protrudes from a side of the holder that faces the interchangeable container, engages in the signal input of the interchangeable container when the latter is inserted and comes into contact with a transmission element which can be moved counter to spring force. During further insertion, the transmission element is forced by the signal transmitter and counter to the spring force to execute a movement by means of which it is pressed against the signal receiver, which is a switching element which is connected to the switching device and is prestressed into an opened position. When the interchangeable container has been inserted completely into the holder, the switching element is displaced by the transmission element into a closed position, in which the printing operation is enabled. In the case of this embodiment, therefore, it is not possible to insert an interchangeable container with unsuitable printing ink completely into the holder, which firstly protects the printer and secondly indicates clearly to the operator of the printer that he is trying to insert an interchangeable container with unsuitable printing ink. 
     In particular, the signal transmitter can be designed as a pin and the transmission element as a pivoting lever, whose axis of rotation runs transversely with respect to the insertion direction and on whose one arm the pin acts. As a result, the pin simultaneously fulfils the task of a signal transmitter and that of a guide element as the interchangeable container is inserted into the holder. Furthermore, a different type of matrix printer, which is serviceable only with a specific different sort of printing ink, can be protected in a particularly simple way against the use of unsuitable interchangeable containers by means of a slight alteration to the position of the pin on the holder and a corresponding alteration in the arrangement of the signal input and of the pivoting lever in the interchangeable container during the production of said printer. 
     The matrix printer can be both an inkjet printer and a dot matrix printer. In the first case, the interchangeable container is designed as an ink container and, in the second case, as an ink ribbon cartridge. Both types of printer can be damaged by an unsuitable ink or ink ribbon impregnation. The invention offers reliable protection for both. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following text, two exemplary embodiments of the invention will be explained with reference to the drawing, in which: 
     FIG. 1 shows a longitudinally sectioned view of a part of a holder with an interchangeable container in its released position in accordance with a first exemplary embodiment of the invention, 
     FIG. 2 shows a longitudinally sectioned view of the part of the holder with the interchangeable container in its inserted position in accordance with the first exemplary embodiment of the invention, 
     FIG. 3 shows a longitudinally sectioned view of a part of a holder with an interchangeable container in its released position in accordance with a second exemplary embodiment of the invention, and 
     FIG. 4 shows a longitudinally sectioned view of the part of the holder with the interchangeable container in its inserted position in accordance with the second exemplary embodiment of the invention. 
     FIG. 5 shows an alternative embodiment of the invention in which the interchangeable container is an ink ribbon cartridge. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a holder  10  for use in an inkjet printer according to a first exemplary embodiment of the invention. As viewed in longitudinal section, the holder  10  has a rectangular frame  12  having a first opening  14  on its upper side, which is used for the insertion and withdrawal of an interchangeable container  16 . During the insertion operation, the inter changeable container  16  is firstly put loosely from above, through the opening  14 , into a compartment  18  which is arranged inside the frame  12  and can be displaced in the latter in an insertion direction  20 . 
     A side wall  22  of the frame  12 , arranged on the left in the illustration of FIG. 1, has on its inner surface, which points in the direction opposite to the insertion direction  20 , a pin  24  which, at approximately a right angle to the inner surface, protrudes from the latter in the direction of the compartment  18 . Likewise formed on the left-hand side wall  22 , underneath the pin  24 , is an opening  26 . It accommodates an electrical switch  28  having a signal receiver in the form of a switching pin  30  which is prestressed elastically into an opened position of the switch  28  and can be moved in the direction  20  counter to a spring force, and which is approximately the same length as the pin  24 . 
     Formed on a left-hand side wall  32  of the moveable compartment  18  and a left-hand side wall  36  of the interchangeable container  16  are, respectively, an upper opening  34  and  38 . The upper openings  34  and  38 , as viewed in cross section, have a shape that corresponds to the cross-sectional shape of the pin  24  and are aligned with the latter when the interchangeable container is inserted into the compartment  18 . 
     In the interior of the interchangeable container  16 , a transmitting device in the form of a two-arm pivoting lever  40  is mounted such that it can be rotated about its axis of rotation  42 , its upper and lower arms  40   a  and  40   b  protruding to an approximately equal length from the axis of rotation  42 . The axis of rotation  42  runs horizontally and, at the same time, transversely with respect to the insertion direction  20 , and is mounted on the interchangeable container  16  close to the side wall  36  and, as viewed in a vertical direction, approximately centrally. 
     A compression spring  44  is fixed at one end to the lower arm  40   b  of the pivoting lever and at the other end to the left-hand side wall  36  of the interchangeable container  16 . As a result, the pivoting lever  40  is prestressed into a position in which the upper arm  40   a  rests with its upper end on the left-hand side wall  36  of the interchangeable container  16 , above the opening  38 . An opening  46  and  48 , respectively, is in each case formed on the left-hand side wall  36  of the interchangeable container  16  and the left-hand side wall of the compartment  18 , which is adjacent in the insertion direction  20 , opposite the lower end of the lower arm  40   b  of the pivoting lever  40 . 
     If the compartment  18  is moved in the insertion direction  20 , the pin  24  moves into the interchangeable container  16  through the openings  34  and  38 , and the switching pin  30  moves into the interchangeable container  16  through the openings  46  and  48 , approximately simultaneously. In the process, the pin  24  encounters the upper arm  40   a  of the pivoting lever  40  and deflects the latter counter to the force of the compression spring  44 . At the same time, its lower arm  40   b  is pivoted in the direction of the side wall  36  of the interchangeable container, which moves the switching pin  30  of the switch  28  as soon as the compartment  18  is resting on the inner surface of the side wall  22  of the frame  12  (FIG.  2 ). With this movement of the switching pin  30  of the switch  28 , an electrical circuit (not illustrated) is closed, and controls the enabling of the inkjet printer for printing operations. Only when the circuit is closed will the inkjet printer be enabled. The maximum possible operating travel of the switching pin  30  is defined in such a way that it must in any case pass through the openings  46 ,  48  before the left-hand side wall  32  of the compartment  18  is resting on the frame  12 . 
     It is also possible to put the interchangeable container  16  directly into the frame  12 . The compartment  18  and, with the latter, the openings  34  and  48  can then be omitted. 
     FIG. 3 shows a holder  50  for use in an inkjet printer according to a second exemplary embodiment of the invention. As viewed in longitudinal section, the holder  50  has a rectangular frame  52  with an insertion opening  54  on its upper side for the insertion and withdrawal of an interchangeable container  56 . During the insertion operation, the interchangeable container  56  is firstly put loosely from above into a compartment  58  which is arranged inside the frame  52  and can be displaced in the latter in a horizontal insertion direction  60 . 
     Arranged at the end of the frame  52  which is on the left in the illustration of FIG. 3 is a closing lever  62 , which is mounted such that it can be rotated about an axis of rotation  64  fixed to the frame. The closing lever  62  may be part of a closure cap (not illustrated further) for the insertion opening  54 . The  35  axis of rotation  64  of the closing lever  62  runs horizontally and, at the same time, transversely with respect to the insertion direction  60 . FIG. 3 shows the closing lever  62  in an opened position, in which it extends upward vertically. As viewed from above, it has a rectangular profile with a long side  67  extending transversely with respect to the insertion direction, and a largely rectangular transverse side  68  which faces the observer and broadens only at its lower end in the shape of a curve  70  which encloses the axis of rotation  64 , the curved edge pointing in the direction opposite the insertion direction  60 . 
     Formed in this broadened portion of the transverse side  68  is a guide slot  72 , which extends essentially parallel to the curved edge  70 . The guide slot  72  has an end close to the axis of rotation and an end remote from the axis of rotation. The guide slot  72  approaches the axis of rotation  64  continuously in a portion  72 ′, starting from its end remote from the axis of rotation  64 , and at a point corresponding to a pivoting angle α of the closing lever  62 , merges into a second portion  72 ″ which extends circularly around the axis of rotation  64 . In the opened position of the closing lever  62  illustrated in FIG. 3, the near end of the guide slot  72  is located above the axis of rotation  64  and at the same height as the latter, as viewed in the insertion direction  60 . The end of the guide slot  72  which is remote from the axis of rotation  64  is, by contrast, located to the right of the axis of rotation  64  and is at the same vertical height as the latter. A guide pin  74  engages in the guide slot  72 , at that end of the guide slot  72  which is remote from the axis of rotation  64  when the closing lever  62  is in the opened position. The guide pin  74  is formed on that side surface of the compartment  58  which faces the observer but is not illustrated in FIG.  3 . 
     The guide pin  74  can alternatively also be arranged on the interchangeable container  56 . In this case, the guide slot  72  is open at its end remote from the axis of rotation  64 , so that it can be disengaged from the guide pin  74  for the insertion and removal of the interchangeable container  56  into and from the compartment  58 . This is particularly advantageous when—according to an alternative embodiment of the holder  50 —the compartment  58  is dispensed with and the interchangeable container  56  is put directly into the frame  52 . 
     On the inner surface of its long side  67  which points to the right in the illustration of FIG. 3, the closing lever  62  has a signal transmitter in the form of a pin  76 , which protrudes approximately vertically from said pin. Its vertical position on the closing lever  62  is determined by the fact that, in the event of a pivoting movement of the closing lever  62  in the direction  66 , it moves into an opening  78  arranged on the upper side of the interchangeable container  56 . This will be discussed in more detail below. 
     Mounted in the interchangeable container  56  such that it can be moved in the axial direction is a transmitting device in the form of a pin  80  which has a vertical longitudinal axis whose imaginary extension runs approximately through the center of the opening  78 . For this purpose, a web  82  having an opening enclosing the cross section of the pin  80  is fixed to an inner wall of the interchangeable container  56 . The pin  80  is held, with the aid of a helical compression spring, which is fastened at its upper end to said pin and at its lower end rests on the underside of the container  56 , in a position in which its upper end is arranged approximately underneath the opening  78  and its lower end is arranged approximately above an opening  86  in the underside of the interchangeable container  56 , said opening being arranged in extension of the pin. 
     An opening  88  on the underside of the compartment  58  is aligned with an opening  94  in the bottom of the frame  52  when the compartment  58  is located in the position shown in FIG. 4. A signal receiver in the shape of a switching pin  90  and belonging to a switch  92  arranged underneath the frame  52  and projects into the opening  94 , without projecting into the interior of the frame  52 . In terms of construction and functioning, the switch  92  corresponds to the switch  28  described with reference to the first exemplary embodiment. 
     In order to insert the interchangeable container  56  put loosely into the frame  52 , the closing lever  62  is pivoted in the direction  66 . In the process, as is known from slotted guides of this or similar type, the guide pin  74  is used to exert a force, acting in the insertion direction  60 , on the compartment  58  or the interchangeable container  56 , so that the interchangeable container  56  and the compartment  58  are moved together in the insertion direction  60 . After the pivoting lever  62  has been pivoted through the angle α the interchangeable container  56  is located in its working position shown in FIG.  4 . If the pivoting lever  62  is pivoted further in the direction of the arrow  66 , the pin  76  arranged on the pivoting lever  62  engages in the opening  78  on the upper side of the interchangeable container  56 , comes into contact with the upper end of the pin  80  in the interchangeable container  56  during further movement of the pivoting lever  62 , and presses said pin, counter to the spring force, downward and successively into the opening  86 , the opening  88  located in the compartment  58  and against the switching pin  90  of the switch  92 . In the position which is illustrated in FIG.  4  and in which the interchangeable container  56  has been inserted completely into the holder  50 , and the pivoting lever  62  is located parallel to the upper side of said container, the pin  80  operates the switch  92  and in this way completes an electrical circuit explained with reference to the first exemplary embodiment, by which means the inkjet printer is enabled to print. 
     The side wall  96  of the frame  52  which is on the left in FIGS. 3 and 4 has a further switch  98  inserted into it in such a way that its switching pin  100  projects into the interior of the frame  52 . In the position illustrated in FIG. 4, the further switch  98  is operated by the left-hand side wall of the compartment  58  or, if the latter is omitted, by the left-hand side wall of the interchangeable container  56 . 
     By means of a logical combination of the switching states of the switches  92  and  98 , a security concept is implemented as follows: if an interchangeable container  56  is to be put into the compartment  58 , the switches  92  and  98  must be unoperated. After the interchangeable container  56  has been put in and the closing lever  62  has been pivoted into the closed position, the switch  92  is operated first, and the further switch  98  is operated only later. Only in the case of this chronological sequence of the switching edges will the printer be enabled. This therefore prevents a manipulation to the effect that one of the switches  92 ,  98  is blocked in its operated position, and in this way a proper interchangeable container is feigned. 
     The above-described security concept can also be used in the case of the holder  10  in the first exemplary embodiment, as illustrated in FIGS. 1 and 2. It is a precondition that a further switching element, corresponding to the further switching element  98  in terms of arrangement and function, is provided. 
     As mentioned, the matrix printer with which an interchangeable ink cartridge of this invention instead of being an inkjet printer can also be a dot matrix printer wherein the ink is provided by way of an ink ribbon cartridge. Such an embodiment of the invention is shown in FIG. 5 wherein an ink ribbon container or cartridge  16 ′ having an ink ribbon  106  and an ink ribbon reservoir  104  is held in use by a holder  10 ′, with the cartridge  16 ′ being moved in the direction  20 ′ to bring it into the position at which it is held in use by the holder  10 ′. The illustrated parts of FIG. 5 called out by primed referenced numbers correspond respectively to the parts of FIGS. 1 and 2 called out by the same unprimed reference numbers, so the signalling functions performed as the ink ribbon cartridge  16 ′ are moved onto the holder  10 ′is the same as those performed when the interchangeable container  16  of FIGS. 1 and 2 is moved onto the holder  10 .