JP2005231123A - Recording head driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To independently switch a drop diameter of a recording droplet ejected from each nozzle of a recording head within a single ejection cycle. <P>SOLUTION: Each nozzle of the recording head of an inkjet printer is provided with heating elements 56 and 58 different in heating value, respectively. Driving circuit 70, which are each provided in such a manner as to correspond to the respective nozzles, are provided with shift registers 72 and 74 which sequentially transfer one-bit driving data input from a data input part 80 and which input the driving data into a latch 76, and a transistor driving part 78 which makes the heating elements 56 and 58 switch to any one of the off-state of the respective heating elements 56 and 58, the on-state of only the heating element 58, the on-state of only the heating element 56, and the on-state of the respective heating elements 56 and 58, via switching elements 64 and 66, in accordance with two-bit driving data retained by the latch 76. In a multiple tone mode, two-bit driving data are each independently input into the respective driving circuits 70 corresponding to the respective nozzles within the single ejection cycle, and the ejection of an ink droplet from each nozzle is independently switched to any one of the state of the nonejection of the ink, the state of a small ink ejection amount, the state of an intermediate-level ink ejection amount and the state of a large ink ejection amount, depending on the two-bit driving data, within the single ejection cycle. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a recording head driving device, and in particular, includes a plurality of nozzles each provided with a plurality of heating elements, and a recording droplet is supplied from each nozzle as the plurality of heating elements provided in each nozzle is turned on / off. The present invention relates to a recording head driving apparatus that drives a recording head to be ejected.

  In an inkjet recording method, an on-demand type has been known as a type of recording method in which ink droplets ejected from nozzles of a recording head are attached to a recording medium to record an image (eg, a character image or a photographic image) on the recording medium. It has been. The on-demand type is a method in which ink droplets are intermittently ejected from nozzles in response to recording information. As a typical example, ink is heated by a heating element provided in the ink chamber, and this heating causes the ink chamber to enter the ink chamber. A thermal method is known in which ink droplets are ejected from nozzles by generated bubbles.

  In addition, in an inkjet recording printer, in order to achieve both high recording speed and improved image quality of recorded images, the amount of ink discharged from the nozzles according to the gradation value of each pixel of image data used for image recording Drop modulation for switching (drop diameter of ink droplets) has been adopted. For example, in Patent Document 1, in a configuration in which two liquid discharge heaters are provided corresponding to a single liquid nozzle, in the first mode, voltage drive pulses of the same condition are simultaneously applied to both heaters so that the volume Vd1 is reduced. A technique is disclosed in which liquid is discharged, and in the second mode, a volume Vd2 (<Vd1) liquid is discharged by applying a driving pulse to one heater under a driving condition different from that in the first mode.

Further, in Patent Document 2, in a head having a configuration in which a plurality of heating elements are arranged inside each nozzle, a single pulse is applied only to one heating element when recording small dots, and one of the heating elements is recorded when recording large dots. A technique is disclosed in which a single pulse is applied to a heat generating element and a divided pulse is applied to the other heat generating element, thereby causing a sufficient difference in size between large and small dots.
Japanese Patent Laid-Open No. 10-16221 Japanese Patent Laid-Open No. 10-230601

  However, the techniques described in Patent Document 1 and Patent Document 2 both have a configuration in which all nozzles are uniformly switched between a large diameter and a small diameter for the droplet diameter of ink droplets ejected from each nozzle of the recording head. It has become. For this reason, when dots to be recorded with large diameter ink droplets and dots to be recorded with small diameter ink droplets are mixed in the dot row to be recorded simultaneously, for example, from the nozzle in the first discharge cycle, Ink droplets are ejected from the nozzles in the next ejection cycle by setting the ejected ink droplets to a large diameter and ejecting ink droplets only from the nozzles corresponding to the dots to be recorded with the large-diameter ink droplets. Control to record the dot row in a plurality of ejection cycles in a pseudo manner, such as switching the nozzle to a small diameter and ejecting ink droplets only from nozzles corresponding to dots to be recorded with small diameter ink droplets. Need to do. Therefore, there has been a problem that a significant improvement in recording speed and image quality cannot be expected.

  The present invention has been made in consideration of the above-described facts, and provides a recording head driving device capable of independently switching the drop diameter of recording droplets ejected from each nozzle of a recording head within a single ejection cycle. Is the purpose.

  In order to achieve the above object, a recording head driving apparatus according to the first aspect of the present invention includes a plurality of nozzles each provided with a plurality of heating elements, and the plurality of heating elements provided in the individual nozzles are turned on and off. A recording head driving device for driving a recording head for discharging recording droplets from each nozzle, provided for each nozzle, and provided for the corresponding nozzle based on the input driving data of a plurality of bits. A plurality of switching means for switching the discharge amount of the recording droplet from the corresponding nozzle to one of two or more discharge amounts by switching on / off of the plurality of generated heating elements, and individually driving each nozzle Input means for inputting drive data of a plurality of bits per single nozzle to each of the plurality of switching means corresponding to each nozzle within a single discharge cycle; It is characterized by comprising.

  The recording head driving apparatus according to the first aspect of the present invention includes a plurality of nozzles each provided with a plurality of heating elements, and recording liquid is supplied from each nozzle as the plurality of heating elements provided in each nozzle is turned on and off. The recording head that ejects droplets is driven. In the recording head, for example, as described in claim 6, the structure of the recording liquid flow path provided corresponding to each nozzle may be a side shooter type or a roof shooter type. There may be. According to the first aspect of the present invention, switching means is provided for each nozzle of the recording head, and the switching means is a plurality of nozzles provided for the corresponding nozzles based on the input driving data of a plurality of bits. By switching on and off the heat generating elements, the recording droplet ejection amount from the corresponding nozzle is switched to one of two or more types of ejection amounts. Further, the input means according to the first aspect of the invention provides a plurality of bits of driving data per single nozzle for independently driving each nozzle to a plurality of switching means corresponding to each nozzle. Each is input within one discharge cycle.

  As a result, each switching means performs a single discharge on / off of a plurality of heating elements provided in the corresponding nozzle based on a plurality of bits of driving data for independently driving each input nozzle. Since switching is performed within each cycle, the ejection amount (that is, the drop diameter) of the recording droplets from each nozzle of the recording head can be switched independently within a single ejection cycle.

  In more detail, the input means and the switching means in the invention described in claim 1 are, for example, as described in claim 2, the input means includes a plurality of shifts provided corresponding to each of the plurality of switching means. The shift register group connected so that the register sequentially transfers 1-bit data includes a plurality of shift register groups provided in the same number as the number of bits of the drive data, and the drive data to be input to the individual switching means. And a data sending section that sequentially sends data of different bits to different shift register groups within a single ejection cycle, and the switching means includes a plurality of shifts. A latch that holds a plurality of bits of drive data transferred by the register group, and a nozzle that corresponds to the latch based on the plurality of bits of drive data held in the latches. It can be configured to include a driving circuit for switching on and off of vignetting the plurality of heating elements.

  In the first aspect of the present invention, the number of heating elements provided in each nozzle of the recording head may be two or more. For example, the first and second heating elements having different thermal energy may be used. In the case where each nozzle is provided, for example, as described in claim 3, the input means inputs 2-bit drive data to each of the plurality of switching means, and the plurality of switching means are input. Based on the 2-bit drive data, each of the first and second heating elements provided in the corresponding nozzle is turned off, only the first heating element is turned on, or only the second heating element is turned on, By turning on each of the first and second heating elements, the ejection amount of the recording droplet can be switched. Thereby, the discharge amount (drop diameter) of the recording droplets from each nozzle of the recording head can be independently switched to any one of the three discharge amounts within a single discharge cycle.

  In the invention described in claim 3, for example, as described in claim 4, a multi-gradation mode is provided as a drive mode of the recording head, and a signal designating the drive mode is input to the input means. When the multi-gradation mode is designated as the drive mode, whether each of the first and second heating elements provided in the individual nozzles of the recording head is turned off or only the first heating element is turned on, It can be configured such that 2 bits of recording data is input per single nozzle indicating whether only the second heat generating element is turned on or each of the first and second heat generating elements is turned on. When the multi-gradation mode is designated as the drive mode, the input means is configured to input the input recording data of 2 bits per single nozzle as drive data to each switching means. It is possible. As a result, the discharge amount (drop diameter) of the recording droplets from each nozzle of the recording head within a single discharge cycle has three types of discharge amounts independently according to 2-bit drive data (recording data). Since it is switched to either one, a multi-tone image can be recorded at high speed.

  In the invention described in claim 3, for example, as described in claim 5, a large drop mode and a small drop mode are provided as drive modes of the recording head, and a signal specifying the drive mode is input to the input means. In addition, when the large drop mode or the small drop mode is designated as the drive mode, the recording data of 1 bit per single nozzle indicating whether or not the recording droplet is ejected from each nozzle of the recording head When the large drop mode is designated as the drive mode, the input unit is a 2-bit unit that turns off the first and second heating elements to the switching unit corresponding to the nozzle that does not eject the recording droplets. For the drive data, the switching means corresponding to the nozzle for ejecting the recording droplets is turned on for each of the first and second heating elements, or the second heating element is used. When the 2-bit drive data for turning on only the first heat generating element that generates a large amount of thermal energy is input and the small drop mode is designated as the drive mode, switching corresponding to the nozzle that does not eject the recording droplets is performed. 2 bits of driving data for turning off the first and second heating elements are switched to the switching means corresponding to the nozzles for ejecting the recording droplets, and the ejection amount of the recording droplets is smaller than that in the large drop mode 2. It is preferable that each bit driving data is input.

  In the invention according to claim 5, when the large drop mode or the small drop mode is designated as the drive mode of the print head, the discharge amount of the print droplet from each nozzle of the print head within a single discharge cycle Since the (drop diameter) is constant, it is difficult to record a multi-tone image, but since the number of bits per single nozzle of the recording data input to the input means is 1 bit, By inputting the recording data to the means in a short time, an image can be recorded at a higher speed. Also, since the ejection volume of the recording droplets from each nozzle is switched depending on whether the driving mode is the large drop mode or the small drop mode, for example, when the image quality of the recorded image is important, the large drop mode is designated and the recording liquid In the case where importance is placed on suppressing the consumption of the recording head, it is possible to switch the drive of the recording head according to the needs, such as designating a small drop mode.

  As described above, the present invention switches on / off of a plurality of heating elements provided in the corresponding nozzle based on the input driving data of a plurality of bits by the switching means provided corresponding to each nozzle. Then, the recording droplet discharge amount from the corresponding nozzle is switched to one of two or more discharge amounts, and multiple bits of driving data per single nozzle for individually driving each nozzle, Since a plurality of switching means corresponding to the nozzles of the recording head are each input within a single ejection cycle, the drop diameters of the recording droplets ejected from each nozzle of the recording head within the single ejection cycle are independent. It has the outstanding effect that it can switch to.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an ink jet printer 10 including a recording head driving device according to the present invention. The ink jet printer 10 is provided with a paper tray 14 on the left side in FIG. 1 on which recording sheets of various sizes can be set. On the right side in FIG. 1, images (for example, character images and photographic images) are provided. A discharge tray 16 for placing the recorded recording paper is provided. A recording paper conveyance path is formed between the paper tray 14 and the discharge tray 16, and a pair of conveyance rollers 22 and 24 rotated by a driving force of a rotation driving unit (not shown) transmitted on the recording paper conveyance path. , 26 are arranged. The conveyance roller pair 22 also has a function of pulling out the recording paper from the paper tray 14, and the recording paper drawn from the paper tray 14 by the conveyance roller pair 22 is conveyed to the discharge tray 16 by the conveyance roller pairs 22, 24, and 26. And placed on the discharge tray 16.

  An ink jet head 20 (corresponding to a recording head according to the present invention) is disposed between the conveying roller pairs 24 and 26. As shown in FIG. 2, the inkjet printer 10 is provided with a pair of chassis 44 at both ends along a direction substantially orthogonal to the recording paper conveyance direction, and the recording paper is conveyed between the pair of chassis 44. A carriage shaft 46 is stretched along a direction substantially perpendicular to the direction. In the vicinity of the carriage shaft 46, an endless carriage feed belt 50 wound around a pair of pulleys 48 is arranged in parallel with the carriage shaft 46. One of the pair of pulleys 48 is connected to a rotation shaft of a carriage motor (not shown) via a driving force transmission mechanism (not shown). When the driving force of the carriage motor is transmitted and the pulley 48 is rotated, Accordingly, the carriage feed belt 50 also moves.

  An ink jet head 20 (carriage 32) supported by the carriage shaft 46 is attached to the carriage feed belt 50 so as to be slidable along the carriage shaft 46. An ink container 52 is attached to the carriage 32. Yes. A plurality of ink storage chambers are formed in the ink storage section 52, and inks of different colors (for example, C, M, Y, BK) for recording a color image on the recording paper S are stored in each ink storage chamber. Reserved. Further, a recording head 34 is provided on the lower surface of the carriage 32 (see also FIG. 1). The inkjet head 20 includes a carriage 32, a recording head 34, and the like. When the carriage feed belt 50 is moved, the inkjet head 20 moves along the carriage shaft 46.

  As shown in FIG. 3, the recording head 34 has a nozzle array in which a plurality of circular holes (nozzles) 36 are formed at a constant pitch along the arrow B direction (the recording paper conveyance direction). A plurality of rows (for example, four or more rows) are arranged along a direction substantially orthogonal to the head surface 34A of the recording head 34 (a surface facing the upper surface of the recording sheet conveyed between the conveying roller pairs 24 and 26). 36, ink discharge ports 38 of the respective nozzles 36 are respectively formed. Inside the recording head 34, a plurality of ink chambers are formed corresponding to the respective nozzle rows, and each ink chamber communicates with each nozzle 36 of the corresponding nozzle row. The individual ink storage chambers of the ink storage section 52 are each in communication with any of a plurality of ink chambers inside the recording head 34, and each nozzle row of the recording head 34 is connected to the ink chamber from the ink storage section 52. Ink of different colors is supplied through the.

  Further, in the middle of the ink flow path from the ink chamber of the recording head 34 to each nozzle 36, a first heat generating element 56 and a second heat generating element 58 for discharging ink droplets from the ink discharge port 38 of the nozzle 36. Each heater unit 60 (see FIG. 4) is provided. The structure of the ink flow path from the ink chamber to each nozzle 36 may be a side shooter type in which ink droplets are ejected in a direction substantially parallel to the heat generating surfaces of the heat generating elements 56 and 58, or the heat generating element 56. , 58 may be a roof shooter type in which ink droplets are ejected in a direction substantially perpendicular to the heating surface.

  Next, the drive unit of the recording head 34 corresponding to the recording head driving apparatus according to the present invention will be described. As shown in FIG. 4, the first heat generating element 56 and the second heat generating element 58 of the heater unit 60 corresponding to each nozzle 36 have one end connected to the power supply line 62 and the other end switching element made of a MOSFET or the like. The first heating element 56 generates heat when a voltage is applied to the first heating element 56 when the switching element 64 is turned on, and the second heating element 58 turns on the switching element 66 when the switching element 66 is turned on. Then, a voltage is applied to generate heat. Note that the heat generating elements used as the first heat generating element 56 and the second heat generating element 58 have a larger heat generation amount when the voltage is applied to the first heat generating element 56 than to the second heat generating element 58. Have been selected.

  The switching elements 64 and 66 constitute a part of a drive circuit 70 provided corresponding to each nozzle 36, and the drive circuit 70 is connected to the gates of the switching elements 64 and 66, respectively. A transistor driver 78 for inputting an on / off control signal to the switching elements 64 and 66 is provided. The transistor drive unit 78 is connected to a latch 76 that holds 2-bit drive data, and the switching elements 64 and 66 correspond to the 2-bit drive data held in the latch 76 during a predetermined ink discharge period. (The heating elements 56 and 58) are turned off, only the switching element 66 (the heating element 58) is turned on, only the switching element 64 (the heating element 58) is turned on, or the switching elements 64 and 66 (the heating element 56). , 58) to switch on each of them.

  Note that the switching elements 64 and 66, the transistor driving unit 78, and the latch 76 correspond to the switching unit according to the first aspect. Specifically, the latch 76 includes the switching elements 64 and 66 in the latch according to the second aspect. The transistor drive unit 78 corresponds to the drive circuit according to claim 2.

  The drive circuit 70 is provided with a first shift register 72 and a second shift register 74 each connected to a latch 76. Although not shown, the first shift register 72 of each drive circuit 70 corresponding to each nozzle 36 belonging to the same nozzle row of the recording head 34 is used for the ink of each nozzle 36 on the head surface 34 </ b> A of the recording head 34. The second shift registers 74 of the drive circuits 70 are sequentially connected in the order of arrangement of the ink discharge ports 38, and are sequentially connected in the order of arrangement of the discharge ports 38. The first shift register group and the second shift register group that are sequentially connected are connected to the data input unit 80, respectively.

  On the other hand, in the inkjet printer 10 according to the present embodiment, as the drive mode of the recording head 34, a multi-tone mode suitable for recording multi-tone images such as photographic images, and a large drop mode suitable for recording character images and the like. , And a small drop mode capable of suppressing ink consumption, and a mode selection signal for specifying in which drive mode the recording head 34 is driven is input to the data input unit 80. The selection of the drive mode may be performed based on an instruction from the user, or may be automatically performed based on the type of image to be recorded on the recording paper.

The data input unit 80 also receives recording data for driving the recording head 34 to record an image to be recorded on a recording sheet. When the multi-gradation mode is designated as the drive mode, the data input unit 80 stores 2-bit print data (single ink discharge amount from each nozzle 36 in four values per single nozzle 36 of the print head 34). (No ink discharge (for example, (00) _B ), discharge amount: small (for example, (01) _B ), discharge amount: medium (for example, (10) _B ), discharge amount: large (for example, (11) _B )) Recording data) is input. Usually, recording data is input by using a total of two input lines at 1 bit / line. However, the data input unit 80 decodes and uses the data sent in a time-division manner at 2 bits / line. Also good. When the large drop mode or the small drop mode is designated as the drive mode, the data input unit 80 stores 1-bit print data (ink from each nozzle 36) for each single nozzle 36 of the print head 34. Binary data (recording data representing ink ejection, ink ejection) is input.

  The data input unit 80 determines 2-bit driving data to be transferred to the driving circuit 70 corresponding to each nozzle 34 of the recording head 34 based on the driving mode specified by the mode selection signal and the input recording data. To do. The upper (or lower) 1-bit data of the 2-bit drive data to be transferred to the drive circuit 70 corresponding to each nozzle 36 belonging to the same nozzle row of the recording head 34 is transferred to the head surface 34A. The data is rearranged in the order of arrangement of the ink discharge ports 38 of the nozzles 36, and the data (bit string) is sequentially sent to the first shift register group corresponding to the nozzles 36 within a predetermined ink discharge period. 1-bit data (the upper (or lower) 1-bit of 2-bit drive data) sequentially sent to the first shift register group is sequentially transferred by the first shift register group.

  Similarly to the above, the data input unit 80 is a low-order (or high-order) 1 bit of 2-bit drive data to be transferred to the drive circuit 70 corresponding to each nozzle 36 belonging to the same nozzle row of the recording head 34. Are rearranged in the order of arrangement of the ink discharge ports 38 of the nozzles 36 on the head surface 34A, and the data (bit string) is transferred to the second shift register group corresponding to the nozzles 36 for a predetermined ink discharge period. Sequentially. 1-bit data (low-order (or high-order) 1-bit of 2-bit drive data) sequentially sent to the second shift register group is sequentially transferred by the second shift register group. The data input unit 80 performs each of the above processes within a predetermined ink ejection period for all the nozzle rows provided in the recording head 34.

  Thereby, on / off of the heat generating elements 56 and 58 of each nozzle 34 of the recording head 34 (that is, ink discharge) is controlled in accordance with a predetermined ink discharge period (2-bit drive data held in the latch 76). 2 bits of drive data is transferred to the drive circuit 70 corresponding to each nozzle 34 within the period), and the transferred 2-bit drive data is stored in the latch 76 of each drive circuit 70 when a predetermined ink discharge period ends. It is held and used for the on / off control (ink discharge) of the heating elements 56 and 58 of each nozzle 34 in the next ink discharge period.

  The data input unit 80 and the first and second shift register groups correspond to the input means according to claim 1 (specifically, claims 2 to 5), and the first and second shift registers. The group corresponds to a plurality of shift register groups described in claim 2, and the data input unit 80 corresponds to the data transmission unit described in claim 2.

  Next, the operation of this embodiment will be described. In the present embodiment, the transistor drive unit 78 controls on / off (ink ejection) of the heating elements 56 and 58 based on the 2-bit drive data held in the latch 76 as shown in the following Table 1, for example. .

In addition, the data input unit 80 indicates that the recording data of 2 bits per single nozzle 36 input when the multi-gradation mode is designated as the drive mode indicates that no ink is ejected from the nozzle 36 (00). _If the print data is _B , the ink discharge amount is small (01) _B , the ink discharge amount is medium (10) _B , and the ink discharge amount is large (11) _B , the input single nozzle The recording data of 2 bits per 36 is transferred as it is to the driving circuit 70 corresponding to each nozzle 36 as 2-bit driving data. As a result, the ejection of ink droplets from the nozzles 36 of the recording head 34 within a single ink ejection period (within a single ejection cycle) indicates no ink ejection and ink ejection amount according to the input recording data. = Small, Ink Ejection Amount = Medium and Ink Ejection Amount = Since each is switched independently, it is possible to record a multi-tone image with high image quality and high speed.

Further, the data input unit 80 indicates that 1-bit print data per single nozzle 36 inputted when the large drop mode or the small drop mode is designated as the drive mode indicates that no ink is ejected from the nozzle 36 ( 0) _B , when there is print data indicating ink discharge (1) _B , as shown in Table 2 below, when the specified drive mode is the large drop mode, “no ink discharge” is displayed on the print data. The 2-bit drive data (that is, (00) _B ) indicating “no ink discharge” is transferred to the drive circuit 70 corresponding to the nozzle 36 indicated as “no ink discharge”. The drive circuit 70 corresponding to 36 outputs 2-bit drive data (that is, (11) _B ) representing “ink discharge amount = large”. When the designated drive mode is the small drop mode, the drive circuit 70 corresponding to the nozzle 36 that is “no ink discharge” on the print data has two bits of drive data (“no ink discharge”) ( That is, (00) _B ) is transferred to the drive circuit 70 corresponding to the nozzle 36 that is “ink ejected” on the recording data, ie, 2-bit drive data (that is, (01) _B ) is output.

  In the large drop mode and the small drop mode, the ink discharge amount from the nozzle 36 that is “with ink discharge” on the recording data is constant (“ink discharge amount = large” in the large drop mode, “ink” in the small drop mode) Since the discharge amount is small, it is not suitable for recording multi-tone images. However, in the large drop mode and the small drop mode, 1-bit print data per single nozzle 36 is input to the data input unit 80. Therefore, the amount of recording data to be input to the data input unit 80 is half that of the multi-gradation mode. Therefore, by inputting recording data to the data input unit 80 in a short time, an image can be recorded at a higher speed, which is suitable for recording an image (for example, a character image) in which the recording speed is important. .

  Also, in the large drop mode, ink droplets having a large drop diameter are ejected from the nozzle 36 "with ink ejection" on the recording data, so that characters can be clearly recorded when recording a character image or the like, and the small drop mode In this case, since ink droplets having a small drop diameter are ejected from the nozzle 36 “with ink ejection” on the recording data, the ink consumption can be suppressed.

  As described above, according to the present embodiment, the drive data corresponding to each nozzle 36 of the recording head 34 is independently input with 2 bits of drive data for each nozzle 36. When the multi-gradation mode is designated, a multi-gradation image can be recorded at high speed with high image quality. In addition, by adopting a configuration in which driving data of 2 bits per single nozzle 36 is independently input to the driving circuit 70 corresponding to each nozzle 36, a large drop mode and a small drop mode are provided as driving modes. It is also possible to select an optimal drive mode (drive of the recording head 34) according to needs and the like.

In the above description, when the designated drive mode is the large drop mode, a 2-bit representing “ink discharge amount = high” is displayed in the drive circuit 70 corresponding to the nozzle 36 that is “with ink discharge” on the print data. When the drive data (that is, (11) _B ) is output and the designated drive mode is the small drop mode, “ink discharge” is output to the drive circuit 70 corresponding to the nozzle 36 that is “with ink discharge” on the print data. Although an example of outputting 2-bit drive data (that is, (01) _B ) representing “amount = small” has been described, the present invention is not limited to this. Two-bit drive data (that is, (10) _B ) representing “ink discharge amount = medium” may be output to the corresponding drive circuit 70. In addition, since it is sufficient that the ink consumption is smaller in the small drop mode than in the large drop mode, if the ink discharge amount in the large drop mode is large, the ink discharge amount may be medium in the small drop mode. The user may select in advance whether the amount is medium or small.

  The multi-gradation mode described above is a driving mode in which the ink discharge amount from a single nozzle 36 is switched to three or more types based on 2-bit recording data (driving data) per single nozzle 36. However, as a driving mode suitable for recording an image (for example, a low-resolution photographic image) in which tone reproducibility is important but high definition is not important, a plurality of driving modes based on data of a plurality of bits per pixel are used. A low-resolution multi-gradation mode for switching the total amount of ink discharged from these nozzles to three or more types may be further provided. In this low resolution multi-gradation mode, a single pixel is represented by a plurality of ink droplets ejected from a plurality of nozzles 36, and a plurality of bits of data per nozzle 36 are input to the data input unit 80. Since it can be realized by inputting, the amount of data to be input to the data input unit 80 can be reduced and an image can be recorded at a higher speed than the multi-gradation mode described above.

  In the above description, the timing and the period for turning on the heat generating elements 56 and 58 are not particularly defined, but the timing and the period for turning on the heat generating elements 56 and 58 may be the same or different. When the timing and period for turning on the heating elements 56 and 58 are different, for example, as shown in FIG. 5, a timing control unit that outputs a timing control signal that defines the timing and period for turning on the first heating element 56 82 and a timing control unit 84 that outputs a timing control signal that defines the timing and period for turning on the second heating element 58 are provided in the drive circuit 70, and AND between the transistor drive unit 78 and the switching elements 64 and 66. Circuits 86 and 88 are provided, and a signal corresponding to the logical product of the on / off control signal output from the transistor driving unit 78 to the switching element 64 and the timing control signal output from the timing control unit 82 is input to the switching element 64. Output from transistor driver 78 to switching element 66 It can be realized by configuring a signal corresponding to the logical product of the timing control signal output from the on-off control signal and a timing control unit 84 which is to be input to the switching element 66. For example, as schematically shown in FIG. 5, if the first heat generating element 56 whose heat generation amount is larger than that of the second heat generating element 58 is turned on twice, the ink discharge amount is set to large / medium / small. This is preferable because the difference in the drop diameter of the ink droplets when switching is greater.

  Further, in the above description, the example in which the two heating elements 56 and 58 are provided in the single nozzle 36 has been described. However, the present invention is not limited to this, and the single nozzle 36 is provided with three or more heating elements. You may do it. In this case, in the multi-gradation mode, it is necessary to input recording data of 3 bits or more per single nozzle 36, but a multi-gradation image can be recorded.

1 is a schematic configuration diagram of an inkjet printer according to an embodiment. It is a top view which shows the mechanism which moves an inkjet head. It is a perspective view which shows the discharge part vicinity of an inkjet head. FIG. 3 is a block diagram illustrating a schematic configuration of a drive unit of a recording head. FIG. 10 is a block diagram illustrating another example of a schematic configuration of a drive unit of a recording head.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Inkjet printer 34 Recording head 36 Nozzle 56 Heating element 58 Heating element 64 Switching element 66 Switching element 70 Drive circuit 72 1st shift register 74 2nd shift register 76 Latch 78 Transistor drive part 80 Data input part

Claims (6)

A recording head driving device that includes a plurality of nozzles each provided with a plurality of heating elements, and that drives a recording head that discharges recording droplets from each nozzle when the plurality of heating elements provided on each nozzle is turned on and off. There,
The amount of recording droplets ejected from the corresponding nozzle by switching on and off the plurality of heating elements provided for each nozzle based on the input multi-bit driving data provided for each nozzle. A plurality of switching means for switching to any one of two or more types of discharge amounts;
Input means for inputting a plurality of bits of driving data per single nozzle for independently driving each nozzle into the plurality of switching means corresponding to each nozzle within a single discharge cycle;
A recording head driving apparatus comprising: In the input means, a plurality of shift registers provided corresponding to each of the plurality of switching means are connected so that one bit of data is sequentially transferred. Within a single discharge cycle, a plurality of shift register groups provided and different bit data of drive data to be input to the individual switching means are sequentially sent to different shift register groups. And a data sending unit for performing
The switching means includes a latch for holding a plurality of bits of driving data transferred by the plurality of shift register groups, and a plurality of heating elements provided in corresponding nozzles based on the plurality of bits of driving data held in the latches 2. A recording head driving apparatus according to claim 1, further comprising a driving circuit for switching on and off. Each nozzle of the recording head is provided with first and second heat generating elements that generate different heat energy as the plurality of heat generating elements,
The input means inputs 2-bit drive data to the plurality of switching means,
The plurality of switching means, based on the input 2-bit drive data, whether to turn off each of the first and second heating elements provided in the corresponding nozzle, or to turn on only the first heating element, 2. The recording head driving apparatus according to claim 1, wherein the ejection amount of the recording droplet is switched by turning on only the second heating element or turning on each of the first and second heating elements. A multi-gradation mode is provided as a driving mode of the recording head, and when the signal specifying the driving mode is input to the input unit and the multi-gradation mode is specified as the driving mode, the recording is performed. The first and second heat generating elements provided in the individual nozzles of the head are turned off, only the first heat generating element is turned on, only the second heat generating element is turned on, or the first and second heat generating elements are turned on. 2 bits of recording data are input per single nozzle indicating whether each element is turned on,
When the multi-gradation mode is designated as the drive mode, the input means inputs 2-bit print data per single nozzle as drive data to each switching means. The recording head driving apparatus according to claim 3. A large drop mode and a small drop mode are provided as the drive mode of the recording head, and a signal designating a drive mode is input to the input means, and a large drop mode or a small drop mode is designated as the drive mode. 1 bit of recording data is inputted per single nozzle indicating whether or not the recording droplets are ejected from the individual nozzles of the recording head,
When the large drop mode is designated as the drive mode, the input means supplies 2-bit drive data for turning off the first and second heating elements to the switching means corresponding to the nozzle that does not eject the recording droplet. The switching means corresponding to the nozzle that discharges the recording droplets turns on the first and second heat generating elements or turns on only the first heat generating element that generates larger heat energy than the second heat generating element. When each of 2-bit drive data is input and the small drop mode is designated as the drive mode, the first and second heating elements are turned off by the switching means corresponding to the nozzles that do not eject the recording droplets. The bit drive data is supplied to the switching means corresponding to the nozzle for ejecting the recording droplet, and the 2-bit driving data in which the ejection amount of the recording droplet is smaller than that in the large drop mode. S recording head driving device according to claim 3, wherein the inputting.   2. The recording head driving apparatus according to claim 1, wherein the recording head has a side shooter type or a roof shooter type in the structure of the recording liquid flow path provided corresponding to each nozzle. .

Images