Abstract:
An ink jet recording apparatus has an ink jet head comprised of a substrate having at least a pair of partition walls with deformable side walls spaced apart at a preselected distance to form a channel for receiving ink and communicating with a nozzle opening, a pair of electrodes each connected to respective ones of the side walls of the partition walls, and a driving circuit for applying a driving voltage to the pair of electrodes to deform the side walls of the partition walls to vary the volume of the channel to thereby eject ink from the channel. A data storage device of the ink jet head stores two or more different types of driving information data of the ink jet head including driving condition data. An external circuit is connected to the driving circuit of the ink jet head and has a setting device for reading at least the driving condition data stored in the data storage device and automatically setting driving conditions of the ink jet head.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an ink jet recording apparatus which is applied to, for example, a printer or a facsimile machine and which discharges ink from a nozzle opening. 
     2. Description of the Related Art 
     Up to now, an ink jet recording apparatus has been known in which an ink jet head for discharging ink from plural nozzles is used to record characters and images on a recording medium. In such an ink jet recording apparatus, the ink jet head opposite to the recording medium is fixed to a head holder, the head holder is mounted to a carriage, and scanning is performed in a direction perpendicular to a conveying direction of the recording medium. 
       FIG. 9  is a schematic exploded view of an example of an ink jet head used in such an ink jet recording apparatus, and  FIGS. 10A and 10B  are sectional views of a main part of the ink jet head. As shown in  FIG. 9  and  FIGS. 10A and 10B , in a piezoelectric ceramic plate  201 , plural grooves  202  are arranged in parallel with each other and are separated from one another by side walls  203 . One end portion of each groove  202  in a longitudinal direction thereof is provided so as to extend to one end surface of the piezoelectric ceramic plate  201  while the other end portion is not extended to the other end surface and gradually becomes shallow. Further, electrodes  205  for application of a driving electric field are formed on surfaces on the opening side of both side walls  203  of each groove  202  in the longitudinal direction. 
     A cover plate  207  is jointed to the opening side of the grooves  202  of the piezoelectric ceramic plate  201  through an adhesive  209 . The cover plate  207  is provided with: an ink chamber  211  that is a concave portion communicated with the shallow other end portion of each groove  202 ; and an ink supply port  212  that penetrates a bottom portion of the ink chamber  211  in an opposite direction to the grooves  202 . 
     Further, a nozzle plate  215  is jointed to an end surface, which is opened with the grooves  202 , of a joint member of the piezoelectric ceramic plate  201  and the cover plate  207 . Nozzle openings  217  are formed at positions, which are opposite to the respective grooves  202 , in the nozzle plate  215 . 
     Note that a wiring substrate  220  mounted with, for example, a driving circuit having a driving IC and the like, is fixed onto a surface, which is on the opposite side to the cover plate  207 , of the piezoelectric ceramic plate  201  on the opposite side to the nozzle plate  215 . In the wiring substrate  220 , wirings  222  connected to the respective electrodes  205  through bonding wires  212  or the like are formed, and a driving voltage can be applied to the electrodes  205  through the wirings  222 . 
     In the ink jet head structured as described above, when ink is filled into the respective grooves  202  from the ink supply port  212 , and a predetermined driving electric field is made to act on both the side walls  203  of the predetermined groove  202  through the electrodes  205 , the side walls  203  are deformed to vary a volume in the predetermined groove  202 , as a result of which an ink droplet in the groove  202  is discharged from the nozzle opening  217 . 
     For example, as shown in  FIG. 11 , in the case where ink is discharged from the nozzle opening  217  corresponding to a groove  202   a , a positive driving voltage is applied to electrodes  205   a  and  205   b  in the groove  202   a , and also, electrodes  205   c  and  205   d  respectively opposite thereto are made to be grounded. Thus, a driving electric field in a direction toward the groove  202   a  acts on side walls  203   a  and  203   b . When the driving electric field is perpendicular to a polarization direction of the piezoelectric ceramic plate  201 , the side walls  203   a  and  203   b  are deformed in the direction of the groove  202   a  due to a piezoelectric thickness slide effect. Thus, a volume in the groove  202   a  is reduced to increase a pressure. As a result, the ink droplet is discharged from the nozzle opening  217 . 
     In attaching the above-described ink jet head to an ink jet recording apparatus, driving conditions of the ink jet head, for example, a so-called voltage rank that indicates a magnitude of a driving voltage to be applied to electrodes in each groove, a type of ink to be used, and resolution, need to be set for each ink jet head. 
     For example, the voltage rank depends on a thickness of a side wall of each groove, and thus differs for each ink jet head due to a manufacturing error or the like. Further, as to identical ink jet heads as well, the voltage rank differs depending on a type of ink to be used, that is, oil-based ink, aqueous ink, or the like. For example, the case of the oil-based ink adopts a voltage of 20 to 24 V, and the voltage rises by approximately 3.0 V when the side wall becomes thick by 4.0 μm. 
     Therefore, according to the prior art, in, for example, the product shipment of ink jet heads, the ink jet heads are individually managed by being attached with labels each showing a voltage rank. Further, in attaching the ink jet head to an ink jet recording apparatus, setting is performed manually while an operator checks the voltage rank written in the label. 
     Accordingly, there is a problem in that an operation for managing and setting a voltage rank for each ink jet head becomes complicated. Further, the voltage rank needs to be set in each case of shipment or exchange of an ink jet head, which is extremely troublesome. In addition, there is a problem in that a setting error is caused by manually setting the voltage rank for each ink jet head. 
     Further, there is a problem in that most of ink jet-head users do not know a the lifetime of the head, and in the case where performance of the head, for example, an ink discharge characteristic is deteriorated, it is difficult for the users to make a judgment on whether the cause of the deterioration is the expired lifetime or the failure of the head. On the other hand, there is a problem in that a manufacturer does not know the head usage status on the user side and thus, it is relatively difficult for the manufacturer to discover the cause of the head failure. 
     It is noted that in the case where the identical ink jet head is used to the end of its lifetime without exchange, the usage status of the head can be grasped with relative ease. Thus, when a problem arises in performance of the head, a projection can be made as to which is the cause between, for example, the lifetime of the head or other factors. However, most users use plural ink jet heads while the heads are replaced with one another, and thus, it is very difficult that the usage status is managed to be grasped for each head. Further, there is also a case where, depending on the user, different types of ink are used with the identical head while being replaced with one another. Therefore, it is very difficult to discover the cause of the head failure. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above, and has an object to provide an ink jet recording apparatus in which an operation for managing and setting driving conditions of an ink jet head can be simplified and a usage status of the ink jet head can be reliably grasped. 
     In order to attain the above described object, according to a first aspect of the present invention, there is provided an ink jet recording apparatus comprising an ink jet head which has a wiring substrate mounted with a driving circuit including a driving IC and in which a driving voltage is applied to an electrode provided on a side wall of a groove formed in a piezoelectric ceramic plate to vary a volume in the groove to thereby discharge ink filled therein from a nozzle opening; and an external circuit connected to the driving circuit. The ink jet head is provided with data storage means for storing driving information data at least including driving condition data of the ink jet head. The external circuit is provided with setting means for reading at least the driving condition data included in the driving information data and automatically setting driving conditions of the ink jet head. 
     According to a third aspect of the present invention, in the first or second aspect of the invention, there is provided an ink jet recording apparatus characterized in that the driving information data includes dot count data obtained by counting the number of times of ink discharge of the ink jet head. 
     According to a fourth aspect of the present invention, in the third aspect of the invention, there is provided an ink jet recording apparatus characterized by further including data writing means for storing the number of times of ink discharge of the ink jet head as the dot count data in the data storage means. 
     According to a fifth aspect of the present invention, in the fourth aspect of the invention, there is provided an ink jet recording apparatus characterized by further including: data managing means for managing the dot count data stored in the data storage means; and notifying means for notifying that the ink jet head is close to the end of its lifetime, in which the data managing means makes the notifying means operate at a time point when the dot count data attains a predetermined value or more. 
     According to the present invention, in the ink jet recording apparatus, the ink jet head is provided with the data storage means for storing a plurality of different types of driving information data including the driving condition data of the ink jet head, and the external circuit is provided with the setting means, which is connected to the data storage means, for reading at least the driving condition data stored in the data storage means and automatically setting the driving conditions of the ink jet head. Therefore, the operation for managing and setting the driving conditions of the ink jet head can be simplified, and the usage status of the ink jet head can be reliably grasped. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings: 
         FIG. 1  is a schematic perspective view of an ink jet recording apparatus in accordance with Embodiment 1 of the present invention; 
         FIG. 2  is a perspective view of an ink jet head in accordance with Embodiment 1 of the present invention; 
         FIG. 3  is a sectional view of a main part of the ink jet head in accordance with Embodiment 1 of the present invention; 
         FIGS. 4A and 4B  are an exploded perspective view and a perspective sectional view of a head chip of the ink jet head, respectively, in accordance with Embodiment 1 of the present invention; 
         FIG. 5  is a control block diagram for explaining a control system of the ink jet recording apparatus in accordance with Embodiment 1 of the present invention; 
         FIG. 6  is a chart showing a procedure of automatically setting a voltage rank of the ink jet head in accordance with Embodiment 1 of the present invention; 
         FIG. 7  is a control block diagram for explaining a control system of an ink jet recording apparatus in accordance with Embodiment 2 of the present invention; 
         FIG. 8  is a chart showing a procedure of announcing exchanging timing of an ink jet head in accordance with Embodiment 2 of the present invention; 
         FIG. 9  is an exploded perspective view showing an outline of an ink jet head according to the prior art; 
         FIGS. 10A and 10B  are sectional views showing the outline of the ink jet head according to the prior art; and 
         FIG. 11  is a sectional view showing the outline of the ink jet head according to the prior art. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Hereinafter, the present invention will be described in detail in accordance with embodiments thereof. 
     Embodiment 1 
       FIG. 1  is a schematic perspective view of an ink jet recording apparatus in accordance with Embodiment 1 of the present invention. 
     An ink jet recording apparatus  10  in this embodiment is provided with plural ink jet heads  20  for respective colors, a carriage  11  to which the ink jet heads  20  are arranged in parallel in a main scanning direction, and ink tanks  90  which constitute a part of an ink reservoir means and each of which supplies ink through an ink supply pipe  91  comprised of a flexible tube. The carriage  11  is mounted on a pair of guide rails  12   a  and  12   b  movably in an axial direction thereof. Further, a driving motor  13  is provided on the one end side of the guide rails  12   a  and  12   b , and a driving force from the driving motor  13  is moved along a timing belt  15  looped around a pulley  14   a  coupled with the driving motor  13  and a pulley  14   b  provided on the other end side of the guide rails  12   a  and  12   b.    
     Further, conveying roller pairs  16  and  17  are provided on both the end portion sides in a direction perpendicular to a conveying direction of the carriage  11  and along the respective guide rails  12   a  and  12   b . The conveying roller pairs  16  and  17  convey a recording medium S on the lower side of the carriage  11  and in the direction perpendicular to the conveying direction of the carriage  11 . 
     Then, while the recording medium S is conveyed by the conveying roller pairs  16  and  17 , scanning with the carriage  11  is performed in a direction perpendicular to a feeding direction of the recording medium S. Therefore, characters, images, and the like are recorded onto the recording medium S by the ink jet heads  20 . 
     Note that the ink jet heads  20  are each of a large type for discharging monochromatic ink, and, for example, the four ink jet heads are mounted in parallel to the carriage  11  in correspondence with ink in four colors of black (B), yellow (Y), magenta (M), and cyan (C) in this embodiment. 
     Further, each ink tank  90  filled with ink of each color is provided at the position where the movement of the carriage  11  in the main scanning direction and the movement of the recording medium S are not interrupted and the position lower by a predetermined amount than a nozzle opening of the ink jet head  20  so as to impart a negative pressure to the inside of the ink jet head  20 . 
     Moreover, the ink jet recording apparatus  10  is provided with an unillustrated external circuit for sending printing data and the like to a driving circuit of each of the ink jet heads  20 , which will be described below in detail. 
     Note that, in the above-described ink jet recording apparatus  10 , a so-called cleaning operation for wiping a surface of a nozzle plate of the ink jet head  20  to remove adhered ink is performed at predetermined timing, for example, timing of starting or timing before a printing start, or arbitrary timing. 
     Here, description will be made of the ink jet head mounted to the above-described ink jet recording apparatus with reference to  FIGS. 2 ,  3 , and  4 A and  4 B. Note that  FIG. 2  is a perspective view of the ink jet head in accordance with this embodiment;  FIG. 3  is a sectional view of a main part of the ink jet head; and  FIGS. 4A and 4B  are an exploded perspective view and a perspective sectional view of a head chip. 
     As shown in the figures, the ink jet head  20  in this embodiment includes a head chip  30 , a channel substrate  40  provided on the side of one surface thereof, and a wiring substrate  50  mounted with a driving circuit and the like for driving the head chip  30 . The respective members are fixed to a base plate  60 . 
     In a piezoelectric ceramic plate  31  that constitutes the head chip  30 , plural channels or grooves  33  communicated with nozzle openings  32  are arranged in parallel with each other and are separated from one another by side walls  34 . One end portion of each groove  33  in a longitudinal direction thereof is provided so as to extend to one end surface of the piezoelectric ceramic plate  31  while the other end portion is not extended toward the other end surface and gradually becomes shallow. Further, electrodes  35  for application of a driving electric field are formed on surfaces on the opening side of the side walls  34  on both sides in a width direction of each groove  33  along a longitudinal direction thereof. 
     Each groove  33  formed in the piezoelectric ceramic plate  31  is formed by, for example, a disk-shaped dice cutter, and a shape of a portion whose depth gradually becomes shallow is determined by a shape of the dice cutter. Further, the electrodes formed in each groove  33  are formed by performing, for example, known evaporation in an oblique direction. 
     One end of a flexible printed circuit (FPC)  51  is connected to the electrodes  35  provided on the opening side of both the side walls  34  of the above-described groove  33 , and the other end of the FPC  51  is connected to a driving circuit  52  on the wiring substrate  50 . Thus, the electrodes  35  are electrically connected to the driving circuit  52 . In addition, a data storage means  100  described below is provided on the wiring substrate  50  in this embodiment. 
     Further, an ink chamber plate  36  is jointed to the opening side of the grooves  33  of the piezoelectric ceramic plate  31 . The ink chamber plate  36  is provided with a common ink chamber  36   a  which is formed so as to penetrate the ink chamber plate  36  and which is provided over all the grooves  33  arranged in parallel with each other. 
     Note that the ink chamber plate  36  can be formed of a ceramic plate, a metal plate, or the like, but preferably is formed of the ceramic plate whose coefficient of thermal expansion is approximate to that of the piezoelectric ceramic plate  31  in consideration of deformation caused after the ink chamber plate  36  is jointed with the piezoelectric ceramic plate  31 . 
     Further, a nozzle plate  37  is jointed to an end surface, which is opened with the grooves  33 , of a joint member of the piezoelectric ceramic plate  31  and the ink chamber plate  36 . Nozzle openings  32  are formed at positions, which are opposite to the respective grooves  33 , in the nozzle plate  37 . 
     In this embodiment, the nozzle plate  37  is larger in area than the end surface, which is opened with the grooves  33 , of the joint member of the piezoelectric ceramic plate  31  and the ink chamber plate  36 . The nozzle plate  37  is obtained by forming the nozzle openings  32  in a polyimide film or the like with the use of, for example, an excimer laser apparatus. Further, although not shown in the figure, a repellent film with repellency for avoiding ink adhesion and the like is provided on a surface, which is opposite to a printed material, of the nozzle plate  37 . 
     Further, a nozzle supporting plate  39  provided with an engagement hole  38  to be engaged with the joint member is jointed to an outer circumferential surface on the side of the end surface, which is opened with the grooves  33 , of the joint member of the piezoelectric ceramic plate  31  and the ink chamber plate  36 . Note that the nozzle supporting plate  39  is jointed to the outside of the end surface, which is jointed to the joint member, of the nozzle plate  37  so as to stably hold the nozzle plate  37 . 
     A surface, which is opposite to the ink chamber plate  36 , of the piezoelectric ceramic plate  31  in the head chip  30  with the above-described structure is jointed and fixed to the base plate  60 . On the other hand, the channel substrate  40  is jointed to one surface of the ink chamber plate  36 . 
     Note that provided on a surface of the channel substrate  40  is a coupling portion  42  which is provided projectedly along the base plate  60  and which is opened with an ink supply path  41 . The coupling portion  42  is connected with one end portion of an ink communicating pipe  43  formed of a stainless-steel pipe or the like. Further, the other end of the ink communicating pipe  43  is connected to an ink reservoir portion  80 , which is connected to an ink tank such as an ink cartridge through the ink supply pipe  91 , for temporarily reservoiring a predetermined amount of ink (refer to  FIG. 1 ). 
     Here, description will be made of the above-described ink jet recording apparatus  10 , particularly the external circuit and the data storage means, with reference to  FIG. 5 . Note that  FIG. 5  is a control block diagram showing a control system of the ink jet recording apparatus. 
     As shown in  FIG. 5 , the ink jet recording apparatus  10  in this embodiment is provided with the ink jet head  20  and an external circuit  110  connected to the ink jet head  20 . The external circuit  110  is connected to an external terminal  120  such as a personal computer (PC). 
     Further, the ink jet head  20  is provided with the head chip  30  and the wiring substrate  50  as described above. In this embodiment, a driving circuit  52  connected to the head chip  30  and the data storage means  100  in which a plurality of types of driving information data of the ink jet head  20  are stored are provided on the wiring substrate  50 . 
     On the other hand, in this embodiment, the external circuit  110  is constituted by: a driving portion  130  connected to the driving circuit  52  through a signal line  111 ; and a control portion  150  which includes a setting means  140  and which is connected to the data storage means  100  through a control line  112 . 
     The driving portion  130  has a function of sending printing data and the like from the external terminal  120  to the ink jet head  20 . That is, when the printing data and the like are input to the driving circuit  52  through the signal line  111 , a predetermined driving voltage is applied to the electrodes  35  of each groove  33  of the head chip  30  from the driving circuit  52 . Then, in the ink jet head  20  in which application of the driving voltage is performed, the volume in each groove  33  is varied to discharge the ink filled therein from the nozzle opening  32 . 
     Further, the control portion  150  is comprised of, for example, a CPU, and has the setting means  140  connected to the data storage means  100  provided therein. The setting means  140  has a function of reading the driving information data stored in the data storage means  100  and automatically setting driving conditions of the ink jet head  20 . 
     For example, in this embodiment, it is set that the setting means  140  reads the magnitude of the driving voltage applied to the electrodes  35  of each groove  33  of the head chip  30 , that is, driving condition data that is voltage rank data, and automatically sets the voltage rank of the ink jet head  20 . 
     Specifically, after reading the voltage rank data stored in the data storage means  100 , the setting means  140  sends the voltage rank data to the driving portion  130  to automatically set the voltage rank of the ink jet head  20  in the driving portion  130 . That is, the voltage rank corresponding to each of the ink jet heads  20  for four colors is automatically set in the driving portion  130  through the setting means  140 . Then, when the printing data and the like are input from the external terminal  120  to the driving portion  130 , a corresponding driving voltage with a predetermined magnitude is applied to each ink jet head  20  through the driving circuit  52 . 
     Note that, as examples of the above-described data storage means  100 , non-volatile memories, such as electrically erasable and programmable read only memory (EEPROM) and flash ROM, and RAM can be given. In this embodiment, the EEPROM is used. 
     Here, description is made of a procedure in which the setting means  140  automatically sets the voltage rank of the ink jet head  20  with reference to  FIG. 6 . Note that  FIG. 6  is a chart showing the procedure of automatically setting the voltage rank of the ink jet head. 
     As shown in  FIG. 6 , first, the ink jet head  20  is attached to the ink jet recording apparatus  10  (step S 1 ). For example, in this embodiment, the ink jet heads for respective colors of black (B), yellow (Y), magenta (M), and cyan (C) are attached to the above-described carriage  11 . Next, an unillustrated power supply of the ink jet recording apparatus  10  is turned on (step S 2 ). Thus, the setting means  140  reads the voltage rank data stored in the data storage means  100  (step S 3 ), and automatically sets the voltage rank corresponding to each of the ink jet heads  20  (step S 4 ). Note that printing is then performed in accordance with the printing data from the external circuit  110  (step S 5 ). Thereafter, in the case where the printing data exists at step S 6  (YES), printing is continuously performed. In the case where the printing data does not exist at step S 6  (NO), the power source is turned off for the completion of printing (step S 7 ). 
     As described above, in the ink jet recording apparatus  10  in this embodiment, the ink jet head  20  is provided with the data storage means  100  for storing the voltage rank data, and the external circuit  110  is provided with the setting means  140  for reading the voltage rank data stored in the data storage means  100  and automatically setting the voltage rank of the ink jet head  20 . Therefore, the operation for managing and setting the voltage rank can be simplified. For example, the setting operation of the voltage rank through manual input is not required in each case of shipment, exchange, or the like of the ink jet head  20 . Thus, the setting operation of the voltage rank can be simplified. Further, since the management and setting of the voltage rank are automatically performed, for example, error input and the like are not caused due to a manual operation. Therefore, an effect of reliable prevention of setting errors is also provided. 
     Further, as in this embodiment, in the ink jet recording apparatus  10  in which the carriage  11  is mounted with the four ink jet heads  20  arranged in parallel and corresponding to ink in four colors, the voltage ranks of the respective ink jet heads  20  are individually and automatically set. Therefore, the operation for setting the voltage rank can be considerably simplified. 
     Embodiment 2 
       FIG. 7  is a control block diagram for explaining a control system of an ink jet recording apparatus in accordance with Embodiment 2 of the present invention. Note that the same parts as those in Embodiment 1 described above are denoted by the same reference numerals, and overlapping description is omitted here. 
     As shown in  FIG. 7 , an ink jet recording apparatus  10 A in this embodiment has the same basic structure as the ink jet recording apparatus  10  in Embodiment 1 except the point in that: a data writing means  160  and a data managing means  170  are provided in a control portion  150 A in an external circuit  110 A; and further, a notifying means  180  connected to the data managing means  170  is provided. 
     The data writing means  160  is connected to a driving portion  130 A and to the data storage means  100 . The data writing means  160  has a function of acquiring the number of times of ink discharge of the ink jet head  20  from the driving portion  130 A and storing the acquired number of times of ink discharge as dot count data in the data storage means  100 . For example, in the case where the dot count data has not been stored in the data storage means  100 , the dot count data is stored in the data storage means  100  as it is. Further, in the case where the dot count data which is used before is stored in the data storage means  100 , the additional number of times of ink discharge is added to the dot count data. 
     Note that the timing at which the dot count data is stored in the data storage means  100  by the data writing means  160  is preferably at, for example, the time of a cleaning operation, the time after printing of one sheet, or the time of turning-on or turning-off of a power supply. 
     On the other hand, the data managing means  170  has a function of managing the dot count data in the data storage means  100 . That is, the data managing means  170  makes the notifying means  180  operate at the time point when the dot count data attains a predetermined value or more in this embodiment. Examples of the notifying means  180  may include a blink of a warning lamp and an alarm. Further, the drive of the ink jet head  20  may be stopped depending on the circumstances. 
     Thus, the exchange timing of the ink jet head  20  can be reliably notified to a user. Note that the time point when the dot count data attains a predetermined value or more indicates the lifetime of the ink jet head  20  in this embodiment. 
     Here, description will be made of the notifying means  180  for notifying the exchange timing of the ink jet head  20  with reference to  FIG. 8 . Note that  FIG. 8  is a chart showing a procedure of notifying the exchange timing of the ink jet head. 
     In this embodiment, as shown in  FIG. 8 , first, the ink jet head  20  is attached to the carriage  11  in the ink jet recording apparatus  10  (step S 11 ). Next, the unillustrated power supply of the ink jet recording apparatus  10  is turned on (step S 12 ). Thus, the data managing means  170  reads the dot count data stored in the data storage means  100  (step S 13 ). Then, in the case where the dot count data read by the data managing means  170  has a predetermined value or more (YES) at step S 14 , the notifying means  180  is made to operate to notify to the user that the ink jet head  20  needs to be exchanged (step S 15 ). On the other hand, in the case where the dot count data has a smaller value than the predetermined value (NO) at step S 14 , the driving portion  130  sends the printing data from the external circuit  110  to the driving circuit  52 , and printing is performed in accordance with the printing data (step S 16 ). Then, the dot count data corresponding to printing at step S 16  is stored in the data storage means  100  by the data writing means  160  at the time of the cleaning operation or the like (step S 17 ). Subsequently, in the case where the printing data exists (YES) at step S 18 , the step returns to step S 13  again, and then, the operation of steps S 14  to S 17  described above is performed. On the other hand, in the case where the printing data does not exist (NO) at step S 18 , the power supply is turned off for the completion of printing (step S 19 ). 
     As described above, the dot count data of the ink jet head  20  is stored in the data storage means  100  in this embodiment. Thus, the usage status of the ink jet head  20  can be grasped with relative ease. Note that the description of the setting means  140  for automatically setting the voltage rank is omitted in this embodiment, but, needless to say, the action effect of the setting means  140  is the same as that in Embodiment 1. 
     Further, in this embodiment, the dot count data of each ink jet head  20  is automatically managed. Thus, this is effective for the case where the plural ink jet heads  20  are mounted to the ink jet recording apparatus  10 A, the case where the plural ink jet heads  20  are frequently replaced with one another, and other cases. 
     Further, when the usage status of the ink jet head  20 , that is, the dot count data can be grasped by the user, in the case where performance of the ink jet head  20 , for example, an ink discharge characteristic is deteriorated, the information on the usage status or dot count data serves as a judgment factor on whether the cause of the deterioration is the lifetime of the ink jet head  20 . On the other hand, a manufacturer can acquire the dot count data of the ink jet head  20  which is acquired by the user, and thus, the dot count data serves as a judgment factor for discovering the cause of the failure of the ink jet head  20 . Therefore, there is also obtained an effect that the cause of the failure of the ink jet head  20  can be promptly discovered in this embodiment. 
     Other Embodiment 
     Hereinabove, the description has been made of the respective embodiments according to the present invention. However, the basic structure of an ink jet recording apparatus is not limited to those described above. 
     In Embodiments 1 and 2 described above, as the driving information data of the ink jet head  20 , the voltage rank data or dot count data is stored in the data storage means  100 . However, the present invention is not limited to this. For example, driving information data such as an ID of each ink jet head  20 , a type of ink to be used, the number of nozzle openings, and resolution may be stored in the data storage means  100 . Note that it is sufficient that the above driving information data is automatically set by the external circuit  110  or  110 A after, for example, the ink jet head  20  is mounted to the ink jet recording apparatus  10  or  10 A and the power supply is turned on. 
     Further, when the number of times of exchange or the like of the ink jet head  20  is stored in the data storage means  100 , the information serves as a judgment factor for projecting the cause of the failure of the ink jet head  20 . 
     Moreover, the dot count data may be counted in one-nozzle units or block units, for example, four-nozzle units, and the counted data may be stored in the data storage means  100 . The dot count data corresponding to a predetermined nozzle unit serves as a more detailed judgment factor for discovering the cause of the failure of the ink jet head  20 . 
     Furthermore, the ink jet head of large type in which monochromatic printing is performed with one head is exemplified in Embodiments 1 and 2. However, the present invention is not limited to this. An ink jet head may be adopted which is of small type in which printing in plural colors can be performed with one head. 
     Note that the description has been made of, as an example, the ink jet recording apparatus  10  mounted with the four ink jet heads  20  in Embodiments 1 and 2. However, an ink jet recording apparatus may be adopted in which ink jet heads  20  are mounted for respective colors in correspondence with ink in five colors or more, for example, five to eight colors. Thus, when the present invention is applied to an ink jet recording apparatus mounted with five or more ink jet heads  20 , the operation for setting the driving conditions of the ink jet head  20  can be considerably simplified, and the dot count data for each ink jet head  20  can be easily managed. 
     As described above, in the ink jet recording apparatus according to the present invention, the ink jet head is provided with the data storage means for storing the driving information data at least including the driving condition data of the ink jet head, and the external circuit is provided with the setting means, which is connected to the data storage means, for reading at least the driving condition data stored in the data storage means and automatically setting the driving conditions of the ink jet head. Therefore, the operation for managing and setting the driving conditions of the ink jet head can be simplified, and the usage status of the ink jet head can be reliably grasped.