JP2018158492A - Large-sized printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large-sized printer capable of reducing a problem caused by a long cable.SOLUTION: A large-sized printer which performs serial printing on a medium with an Ad short side with or more includes: a printing head part that has a first connector and discharges a liquid; a first substrate having a second connector and a third connector; a second substrate having a fourth connector; a first cable of which one end is connected to the first connector and the other end is connected to the second connector; and a second cable of which one end is connected to the third connector and the other end is connected to the fourth connector, where on the other end of the first cable, terminals are provided on only one surface of the first cable, on one end of the second cable, terminals are provided on only one surface of the second cable, the number of the terminals provided on the other end of the first cable is the same as the number of the terminals provided on one end of the second cable, and a terminal surface provided with the terminal is provided in the second connector and a terminal surface provided with the terminal is provided in the third connector face in different directions.SELECTED DRAWING: Figure 21

Description

  The present invention relates to a large format printer.

  2. Related Art An ink jet printer that prints an image or a document by ejecting ink is known that uses a piezoelectric element (for example, a piezo element). Piezoelectric elements are provided corresponding to each of a plurality of nozzles in a head (print head), and each is driven according to a drive signal, whereby a predetermined amount of ink (liquid) is ejected from the nozzles at a predetermined timing. , Forming dots. Since the piezoelectric element is a capacitive load such as a capacitor when viewed electrically, it is necessary to supply a sufficient current to operate the piezoelectric element of each nozzle. For this reason, the above-described ink jet printer has a configuration in which the drive circuit supplies a high voltage drive signal amplified by the amplification circuit to the head to drive the piezoelectric element.

  Patent Document 1 discloses an ink jet printer that supplies a control signal and a drive signal from a control board attached to a casing of a printing apparatus to a print head via a flexible cable. In Patent Document 2, a carriage on which a print head (inkjet head) and a drive circuit that generates drive pulses and applies them to a print head are reciprocated to eject ink droplets from the print head. A recording apparatus for recording an image is disclosed.

JP 2014-133358 A Japanese Patent No. 4196523

  By the way, in a large format printer (LFP: Large Format Printer) capable of performing serial printing on a medium having an A3 short side width or more, the moving distance of the print head becomes long, and the print head and the control board. Can be 1 m or longer, the inductance and impedance of the signal line is increased. Therefore, in the large format printer, when the control signal and the drive signal are supplied from the control board to the print head as in the ink jet printer disclosed in Patent Document 1, if the inductance of the signal line increases, the overshoot of the drive signal If the undershoot increases and an overvoltage exceeding the withstand voltage is instantaneously applied to a circuit or a drive element mounted on the printhead, the printhead may be damaged. Further, when the impedance of the signal line is increased, the voltage drop of the drive signal is increased, so that the printing accuracy and the printing stability are reduced, or malfunction such as erroneous ink ejection may occur. In addition, if the cable connecting the print head and the control board becomes long, the crosstalk between the drive signal and the control signal increases, so the low-voltage control signal is easily affected by the high-voltage drive signal, resulting in erroneous ejection. Such a malfunction may occur. In addition, if the cable connecting the print head and the control board becomes long, static electricity is generated due to friction between the printer housing and the cable as the print head moves, and the cable is easily charged. A circuit that operates at a low power supply voltage may cause electrostatic breakdown and the print head may be damaged.

In addition, in a large format printer, when a drive circuit is mounted on a carriage as in the recording apparatus disclosed in Patent Document 2, the weight of a movable part for performing serial printing increases.
Since the load on the motor for reciprocating the movable part increases, an expensive motor is required, and it is difficult to reduce the cost. Moreover, there is a possibility that the discharge accuracy and the discharge stability are lowered due to the heat generation of the drive circuit. Furthermore, since the vibration during reciprocating movement increases as the weight of the movable part increases, there is a risk that the printing accuracy and printing stability may be reduced even by a large vibration of the print head.

  The present invention has been made in view of the above problems, and according to some aspects of the present invention, a large format capable of reducing at least one of the problems caused by a long cable. A printer can be provided.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the following aspects or application examples can be realized.

[Application Example 1]
The large-format printer according to this application example is a large-format printer capable of performing serial printing on a medium having an A3 short side width or more, and includes a print head unit that includes a first connector and discharges liquid, A first board having two connectors and a third connector; a second board having a fourth connector; and a first cable having one end connected to the first connector and the other end connected to the second connector. A second cable connected at one end to the third connector and connected at the other end to the fourth connector, and the other end of the first cable has a terminal only on one side of the first cable. The one end of the second cable is provided with a terminal only on one side of the second cable, the number of the terminals provided on the other end of the first cable, and the second cable At one end The number of vignetting said terminal are the same, the terminal surface of the terminal is provided in said second connector, and a terminal face of the terminal in the third connector is provided is oriented in different directions.

  “Serial printing” is a printing method in which the print head unit moves to perform printing. The first cable and the second cable may be flexible flat cables. The print head unit may include a drive element, and the liquid may be ejected when a drive signal is applied to the drive element and the drive element is driven. The driving element may be, for example, a piezoelectric element or a heat generating element.

  In the large format printer according to this application example, one drive signal is output from the fifth connector provided on the second substrate, propagates through the second cable, and is input from the third connector to the first substrate. The other drive signal is output from the sixth connector provided on the second substrate, propagates through the third cable, and is input from the fourth connector to the first substrate. In the first substrate, these drive signals are combined to be output as one drive signal from the second connector, propagated through the first cable, and input from the first connector to the print head unit. That is, the drive signal propagates through two cables and is supplied from the second substrate to the first substrate, and further propagates through one cable and is supplied to the print head unit. The inductance and impedance of the signal line through which the drive signal propagates are reduced as compared with the case where the signal is propagated through one cable and supplied to the print head unit. Therefore, according to the large format printer according to this application example, since it is possible to perform serial printing on a medium having an A3 short side width or more, a signal line through which a drive signal propagates to the print head unit becomes long. Overshoot or undershoot of the drive signal caused by the inductance of the signal line is reduced, and the possibility that the print head unit will fail or malfunction is reduced. Further, according to the large format printer according to this application example, the signal line through which the drive signal propagates to the print head unit becomes long, but the voltage drop of the drive signal caused by the impedance of the signal line is reduced, and high printing is performed. Accuracy and printing stability can be realized.

  In a large format printer capable of performing serial printing on a medium having an A3 short side width or longer, a signal line through which various signals propagate to the print head unit becomes long, so that the impedance and inductance of the signal line are reduced. In some cases, a large number of substrates and a large number of cables are used for the purpose. Therefore, it is easy to make a mistake in inserting each cable into each board. On the other hand, according to the large format printer according to this application example, on the first substrate, the first cable is connected to the second connector, the second cable is connected to the third connector, and the third cable is connected to the fourth connector. However, since the terminal surface of the second connector and the terminal surface of the third connector are in different directions, it is difficult for the first cable and the second cable to be inserted incorrectly. Since the terminal surfaces of the 4 connectors face different directions, it is difficult for the first cable and the third cable to be inserted incorrectly. Therefore, according to the large-format printer according to this application example, the possibility that the print head unit breaks down or malfunctions due to the wrong insertion of the cable in the first substrate is reduced.

[Application Example 2]
In the large format printer according to the application example described above, the terminal surface of the second connector and the terminal surface of the third connector may face in a perpendicular direction.

  According to the large-sized printer according to this application example, in the first board, since the terminal surface of the second connector and the terminal surface of the third connector are oriented in a direction orthogonal to each other, there is a mistake in inserting the first cable and the second cable. This is unlikely to occur and the terminal surface of the second connector and the terminal surface of the fourth connector are orthogonal to each other, so it is difficult for the first cable and the third cable to be inserted incorrectly. As a result, the possibility of malfunction or malfunction of the print head unit is reduced.

[Application Example 3]
In the large format printer according to the application example, the terminal surface of the second connector and the terminal surface of the third connector may face in opposite directions.

  According to the large format printer according to this application example, in the first board, the terminal surface of the second connector and the terminal surface of the third connector are opposite to each other, so that the first cable and the second cable are inserted incorrectly. Because the terminal surface of the second connector and the terminal surface of the fourth connector are facing in opposite directions, it is difficult for the first cable and the third cable to be inserted incorrectly. This reduces the possibility that the print head will fail or malfunction.

[Application Example 4]
In the large format printer according to the application example described above, a maximum width in which the serial printing is possible may be 24 inches or more and 75 inches or less.

  When the maximum width capable of serial printing is not less than 24 inches and not more than 75 inches, the total length of the signal line through which the drive signal propagates can be about 1 m to 3 m, so that the impedance and inductance of the signal line increase. Therefore, when a large number of boards or a large number of cables are used to reduce the impedance or inductance of the signal line, it is very easy to make a mistake in inserting each cable into each board. According to the printer, the above effect is greater. If the maximum width that can be serially printed exceeds 75 inches, the impedance and inductance of the signal line through which the drive signal propagates become too large. Since there is a greater possibility that the print head unit will fail or malfunction due to undershoot, the above effect is difficult to obtain.

[Application Example 5]
In the large format printer according to the application example described above, the maximum width capable of serial printing may correspond to any of 24 inches, 36 inches, 44 inches, and 64 inches.

  According to the large format printer according to this application example, it is possible to reduce a possibility that the print head unit may break down or malfunction in a particularly demanding 24-inch compatible printer, 36-inch compatible printer, 44-inch compatible printer, or 64-inch compatible printer. be able to.

[Application Example 6]
In the large format printer according to the application example, the print head unit may eject the liquid at a frequency of 30 kHz or more.

  The higher the frequency of ejecting the liquid (the higher the speed of printing), the more sudden the voltage change of the drive signal, and the greater the overshoot and undershoot. Therefore, when a large number of boards and a large number of cables are used to reduce the impedance and inductance of the signal line through which the drive signal propagates, it is very easy to make a mistake in inserting each cable into each board. According to the large format printer according to this application example, since the high-speed printing is performed at a frequency of 30 kHz or more, in particular, the overshoot or undershoot of the drive signal tends to be large, the above effect is greater.

It is an external appearance schematic diagram of a large format printer. It is a figure which shows the lower surface (ink discharge surface) of a head. FIG. 2 is a diagram schematically illustrating an internal configuration of a large format printer. It is a block diagram which shows the electric constitution of a large format printer. It is a figure which shows schematic structure corresponding to one discharge part. It is a figure which shows the waveform of the drive signals COMA and COMB. It is a figure which shows the waveform of the drive signal VOUT. It is a figure which shows the structure of a drive signal selection circuit. It is a figure which shows the decoding content in a decoder. It is a figure which shows the structure of a selection part. It is a figure for demonstrating operation | movement of a drive signal selection circuit. It is a figure which shows the circuit structure of a drive circuit. It is a figure for demonstrating operation | movement of a drive circuit. It is a figure for demonstrating the connection relation of a board | substrate and a cable. It is a figure which shows the structure of a cable. It is a figure which shows the structure of a cable. It is a figure which shows the specific example of the relationship between the number and signal of the signal line of a cable, and the number and signal of the connection terminal of a connector. It is a figure which shows the specific example of the relationship between the number and signal of the signal line of a cable, and the number and signal of the connection terminal of a connector. It is a figure which shows the specific example of the relationship between the number and signal of the signal line of a cable, and the number and signal of the connection terminal of a connector. It is a figure which shows arrangement | positioning of the connector of a drive circuit board. It is a figure which shows arrangement | positioning of the connector of a 1st relay board | substrate. It is a figure which shows arrangement | positioning of the connector of a 2nd relay board | substrate. It is a figure which shows the arrangement | positioning of a board | substrate and a cable schematically. It is a figure which shows an example of a shielded cable. It is a figure which shows the specific example of the relationship between the number and signal of the signal line of a cable, and the number and signal of the connection terminal of a connector. It is a figure which shows an example of a daisy chain.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The drawings used are for convenience of explanation. The embodiments described below do not unduly limit the contents of the present invention described in the claims. Also, not all of the configurations described below are essential constituent requirements of the present invention.

1. Overview of Large Format Printer The large format printer (large format printer) according to this embodiment forms ink dot groups on a print medium such as paper by ejecting ink according to image data supplied from an external host computer. Thus, the inkjet printer prints an image (including characters, graphics, etc.) according to the image data.

  FIG. 1 is a schematic external view of a large format printer 1 according to the present embodiment. As shown in FIG. 1, a large format printer 1 according to the present embodiment is a serial scan type (serial printing type) large format printer, and includes a main body 2 and a support stand 3 that supports the main body 2. In the present embodiment, the large format printer is a printer capable of performing serial printing on a medium (print medium) having a width equal to or larger than the A3 short side width (297 mm). In other words, the A3 short side width (297 mm). ) A printer capable of performing serial printing with the above-mentioned printing width. In the present embodiment, in the large-format printer 1, the moving direction of the carriage 24 is described as a main scanning direction X, the transport direction of the printing medium P is set as a sub-scanning direction Y, and the vertical direction is set as Z. In addition, although the main scanning direction X, the sub-scanning direction Y, and the vertical direction Z are illustrated in the drawing as three axes that are orthogonal to each other, the arrangement relationship of each component is not necessarily limited to that orthogonal. In the following description, when necessary, the main scanning direction X, the sub-scanning direction Y, and the vertical direction Z will be described by distinguishing the positive direction and the negative direction. With respect to the main scanning direction X, the direction in which the carriage 24 moves away from the home position, which will be described later, is the positive direction (the direction of the arrow in FIG. 1), and the opposite direction is the negative direction. For the sub-scanning direction Y, the direction in which the print medium P is conveyed from upstream to downstream is the positive direction (the direction of the arrow in FIG. 1), and the opposite direction is the negative direction. For the vertical direction Z, the direction opposite to the direction of gravity is defined as the positive direction (the direction of the arrow in FIG. 1), and the direction of gravity is defined as the negative direction.

  As shown in FIG. 1, the main body 2 includes a supply unit 4 that supplies a print medium P (for example, roll paper), a head unit 20 that discharges ink droplets to the print medium P, and performs printing on the print medium P. The discharge unit 6 that discharges the print medium P printed by the head unit 20 to the outside of the main body 2, the operation unit 7 that performs operations such as execution and stop of printing, and the discharged ink (liquid) are stored. An ink storage unit 8. Although not shown, a USB port and a power port are disposed on the rear surface of the large format printer 1. That is, the large format printer 1 is configured to be connectable to a computer or the like via a USB port.

  The head unit 20 includes a carriage 24 and a head 21 mounted on the carriage 24 so as to face the print medium (roll paper) P.

  The head 21 is a liquid ejecting head for ejecting ink droplets (droplets) from a large number of nozzles. Specifically, the head 21 includes a piezoelectric element 60 (see FIGS. 4 and 5) that is a driving element. When a driving signal is applied to the piezoelectric element 60 and the piezoelectric element 60 is driven, ink (liquid) is supplied. Discharge.

  FIG. 2 is a diagram illustrating the lower surface (ink ejection surface) of the head 21. As shown in FIG. 2, on the ink ejection surface of the head 21, there are mainly six nozzle plates 632 each having a plurality of nozzle rows 650 in which a large number of nozzles 651 are arranged at a predetermined pitch Py along the sub-scanning direction Y. They are arranged side by side along the scanning direction X. Between the two nozzle rows 650 provided on each nozzle plate 632, each nozzle 651 is shifted by half the pitch Py in the sub-scanning direction Y. Thus, in the present embodiment, the 12 nozzle rows 650 (the first nozzle row 650a to the twelfth nozzle row 650l) are provided on the ink ejection surface of the head 21.

  The carriage 24 is supported by the carriage guide shaft 32 and moves (reciprocates) in the main scanning direction X. At this time, the print medium P is conveyed in the sub-scanning direction Y. That is, the large format printer 1 according to the present embodiment performs serial printing in which the head unit 20 including the carriage 24 on which the head 21 that ejects ink droplets is mounted moves (reciprocates) in the main scanning direction X and performs printing.

  A plurality of ink cartridges 22 are attached to the ink reservoir 8, and each ink cartridge 22 is filled with ink of a corresponding color. In FIG. 1, four ink cartridges 22 corresponding to four colors of C (cyan), M (magenta), Y (yellow), and B (black) are illustrated, but the ink cartridges 22 are limited to this configuration. For example, the ink reservoir 8 may be provided with five or more ink cartridges 22 or ink cartridges 22 corresponding to colors such as gray, green, and violet. The ink stored in each ink cartridge 22 is supplied to the head 21 via the ink tube 9. The large format printer 1 may have a configuration in which a plurality of ink cartridges 22 are attached to the carriage 24.

  FIG. 3 is a diagram schematically showing an internal configuration when the large-format printer 1 is viewed in the negative direction of the sub-scanning direction Y. As shown in FIG. 3, the large format printer 1 includes a head unit 20, a carriage guide shaft 32, a platen 33, a capping mechanism 35, and a maintenance mechanism 80.

  The head unit 20 moves (reciprocates) within the movable region R along the carriage guide shaft 32 based on control of a carriage movement mechanism (not shown). The head 21 and the second relay substrate 103 are mounted on the carriage 24 of the head unit 20. A head substrate 104 is mounted on the head 21, and the ink ejection surface of the head 21 faces the print medium P.

  The platen 33 is provided with a roller (not shown) that conveys the print medium P, conveys the print medium P in the sub-scanning direction Y, and holds the print medium P when ink droplets are ejected onto the print medium P. To do. That is, the maximum width that can be serially printed by the head unit 20 of the large format printer 1 (hereinafter referred to as “maximum printing width”) is equivalent to the platen width PW that is the width of the platen 33 in the main scanning direction X. The platen width PW is set wider than the standard dimension Ws of the medium width W that is the width of the print medium P in the main scanning direction X in order to stably hold and transport the print medium P. In the present embodiment, the platen width PW (that is, the maximum printing width) satisfies Ws <PW ≦ Ws × 1.15 with respect to the standard dimension Ws. In other words, the large format printer 1 corresponding to the standard dimension Ws is a printer having a maximum printing width larger than the standard dimension Ws and 115% or less of the standard dimension Ws.

For example, the large format printer 1 having a standard width Ws of 24 inches for the medium width W is a printer corresponding to a maximum print width of 24 inches (referred to as a “24-inch compatible printer”). Is a printer that is larger than 24 inches and 27.6 inches or less. The large format printer 1 having a standard width Ws of 36 inches for the medium width W is a printer corresponding to a maximum print width of 36 inches (referred to as a “36-inch compatible printer”), and specifically, the maximum print width. Is a printer that is larger than 36 inches and 41.4 inches or less. The large-format printer 1 having a standard width Ws of 44 inches for the medium width W is a printer corresponding to a maximum print width of 44 inches (referred to as a “44-inch compatible printer”), and specifically, the maximum print width. Is a printer that is larger than 44 inches and not larger than 50.6 inches. The large format printer 1 having a standard width Ws of 64 inches for the medium width W is a printer corresponding to a maximum print width of 64 inches (referred to as a “64-inch compatible printer”). Is a printer that is larger than 64 inches and not larger than 73.6 inches.

  A capping mechanism 35 that seals the nozzle formation surface (ink discharge surface) of the head 21 is provided at the home position where the head unit 20 moves (reciprocates). The home position is also a position where the large format printer 1 waits for the head unit 20 when printing is not being performed. That is, it is preferable that the capping mechanism width CW, which is the width of the home position (capping mechanism 35) in the main scanning direction X, is greater than or equal to the head unit width HW which is the width of the head unit 20 in the main scanning direction X.

  In the movable region R of the head unit 20, a maintenance mechanism 80 is provided in a place farthest from the home position. As a maintenance process, the maintenance mechanism 80 removes foreign matter such as cleaning powder (pumping process) for sucking thickened ink or bubbles in the discharge unit 600 by a tube pump (not shown) and paper dust adhering to the vicinity of the nozzle. A wiping process of wiping with a wiper is performed. During the execution of the maintenance process, it is preferable that the head unit 20 and the platen 33 that is the printing area do not overlap when viewed from the vertical direction Z. That is, the maintenance mechanism width MW, which is the width of the maintenance mechanism 80 in the main scanning direction X, is preferably provided to be equal to or larger than the head unit width HW, which is the width of the head unit 20 in the main scanning direction X.

  Further, the large format printer 1 includes a control board 100, a drive circuit board 101, a first relay board 102, and a plurality of cables 19. Between the control board 100 and the drive circuit board 101, between the drive circuit board 101 and the first relay board 102, between the first relay board 102 and the second relay board 103, and between the second relay board 103 and the head board 104. 1, between the first relay substrate 102 and the head substrate 104, and between the control substrate 100 and the head substrate 104 are connected by one or a plurality of cables 19. Then, the drive signal and control signal propagated through the cable 19 are supplied to the head substrate 104, and ink is ejected from each nozzle 651 formed on the ejection surface of the head 21 based on the drive signal and control signal. In the present embodiment, the cable 19 is a flexible flat cable (FFC). In the present embodiment, the control board 100, the drive circuit board 101, and the first relay board 102 are fixed at predetermined locations in the casing of the large format printer 1. Accordingly, the cables 19 connecting the control board 100 and the drive circuit board 101 and between the drive circuit board 101 and the first relay board 102 are deformed as the head unit 20 moves (reciprocates). do not do. In contrast, between the first relay board 102 and the second relay board 103, between the second relay board 103 and the head board 104, between the first relay board 102 and the head board 104, and the control board. The cable 19 that connects between the head substrate 104 and the head substrate 104 is deformed as the head unit 20 reciprocates. The details of the connection relationship between these boards and the cable 19 will be described later.

2. Electrical Configuration of Large Format Printer FIG. 4 is a block diagram showing an electrical configuration of the large format printer 1 according to the present embodiment. As described above, the large format printer 1 includes the control board 100, the drive circuit board 101, the first relay board 102, the second relay board 103, and the head board 104.

  As shown in FIG. 4, the control board 100 is provided with (mounted on) a control unit 111, a power supply circuit 112, and a control signal transmission unit 113.

  The control unit 111 is realized by a processor such as a microcontroller, for example, and generates various data and signals based on various signals such as image data supplied from a host computer.

  Specifically, the control unit 111 is a 2-bit drive that is digital data that is a source of drive signals COMA and COMB that drive the ejection units 600 of the head 21 based on various signals from the host computer. Data COMA_D0 and COMA_D1 and drive data COMB_D0 and COMB_D1 are generated. The drive data COMA_D0 and COMA_D1 propagate through the cable 19 (see FIG. 3) and are supplied to the drive circuits 50a and 50c provided on the drive circuit board 101. Similarly, the drive data COMB_D0 and COMB_D1 propagate through the cable 19 and are supplied to the drive circuits 50b and 50d provided on the drive circuit board 101.

  The control unit 111 also includes six print data signals SI1 to SI6, a latch signal LAT, and a change signal as a plurality of types of control signals for controlling the discharge of the liquid from the discharge unit 600 based on various signals from the host computer. A CH and a clock signal SCK are generated and output to the control signal transmission unit 113.

  Further, the control unit 111 performs various processes according to the temperature signal TH and the abnormality signal XHOT supplied from the drive circuit board 101. For example, the control unit 111 generates drive data COMA_D0, COMA_D1 and drive data COMB_D0, COMB_D1 so that the waveforms of the drive signals COMA, COMB are corrected according to the temperature signal TH. Further, when the abnormality signal XHOT is active (for example, high level) (when indicating abnormality), the control unit 111 supplies the drive data COMA_D0 and COMA_D1 and the drive data COMB_D0 and COMB_D1 to the drive circuits 50a to 50d. And the ejection of ink from the head 21 is stopped.

  In addition to the above processing, the control unit 111 grasps the scanning position (current position) of the carriage 24 (head unit 20), and drives a carriage motor (not shown) based on the scanning position of the carriage 24. I do. Thereby, the movement of the carriage 24 in the main scanning direction X is controlled. Further, the control unit 111 performs a process of driving a transport motor (not shown). Thereby, the movement of the print medium P in the sub-scanning direction Y is controlled.

  Further, the control unit 111 causes the maintenance mechanism 80 (see FIG. 3) to perform a maintenance process (cleaning process (pumping process) or wiping process) for recovering the ink ejection state of the head 21 normally.

The control signal transmission unit 113 converts the six print data signals SI1 to SI6 output from the control unit 111 into differential signals (SI1 +, SI1-) to (SI6 +, SI6-), respectively. Further, the control signal transmission unit 113 converts the latch signal LAT, change signal CH, and clock signal SCK output from the control unit 111 into differential signals (LAT +, LAT−), (CH +, CH−), (SCK +, To SCK-). Then, these differential signals (SI1 +, SI1-) to (SI6 +, SI6-), (LAT +, LAT−), (CH +, CH−), (SCK +, SCK−) propagate through the cable 19 and the head. The signal is supplied to the control signal receiving unit 115 provided on the substrate 104. The control signal transmission unit 113 is, for example, LV
A differential signal of DS (Low Voltage Differential Signaling) transfer method is generated. Since the differential signal of the LVDS transfer system has an amplitude of about 350 mV, high-speed data transfer can be realized. Note that the control signal transmission unit 113 may generate differential signals of various high-speed transfer methods such as LVPECL (Low Voltage Positive Emitter Coupled Logic) and CML (Current Mode Logic) other than LVDS.

  The power supply circuit 112 generates a high power supply voltage signal VHV having a constant voltage (for example, 42V) and a ground voltage signal GND having a ground voltage (0V). The high power supply voltage signal VHV propagates through the cable 19 and is supplied to drive circuits 50 a to 50 d provided on the drive circuit board 101 and drive signal selection circuits 120 a to 120 f provided on the head board 104. The ground voltage signal GND propagates through the cable 19 and is supplied to each circuit provided on the drive circuit board 101 and each circuit provided on the head board 104.

  The drive circuit board 101 is provided (mounted) with four drive circuits 50a to 50d and a voltage conversion circuit 114.

  The voltage conversion circuit 114 converts the high power supply voltage signal VHV (for example, 42V) into a low power supply voltage signal VDD having a constant voltage (for example, 3.3V). In addition, the voltage conversion circuit 114 converts the high power supply voltage signal VHV (for example, 42V) into a power supply voltage signal GVDD having a constant voltage (for example, 7.5V) and supplies the power supply voltage signal to the drive circuits 50a to 50d.

  The drive circuits 50a and 50c generate the drive signal COMA based on the 2-bit drive data COMA_D0 and COMA_D1 output from the control unit 111. Similarly, the drive circuits 50b and 50d generate the drive signal COMB based on the 2-bit drive data COMB_D0 and COMB_D1 output from the control unit 111. In the present embodiment, the drive circuits 50a and 50c integrate the drive data COMA_D0 and COMA_D1, and generate the drive signal COMA by D / A converting and amplifying the accumulated data. Similarly, the drive circuits 50b and 50d integrate the drive data COMB_D0 and COMB_D1, and generate the drive signal COMB by D / A converting and amplifying the accumulated data. That is, the drive data COMA_D0 and COMA_D1 and the drive data COMB_D0 and COMB_D1 are digital data indicating differences with respect to the latest integrated data. Note that the control unit 111 generates integrated data itself (drive data corresponding to digital data obtained by analog / digital conversion of the waveforms of the drive signals COMA and COMB) as drive data, and the drive circuits 50a to 50d generate the drive data. The drive signals COMA and COMB may be generated by D / A conversion and amplification.

  In addition, the drive circuits 50a to 50d generate a reference voltage signal VBS (for example, 6V) from the power supply voltage signal GVDD output from the voltage conversion circuit 114. The drive circuits 50a to 50d are different only in input drive data and output drive signals, and may have the same circuit configuration, and details thereof will be described later.

The drive signal COMA and the reference voltage signal VBS generated by the drive circuit 50a are separated into three drive signals COMA1 to COMA3 and three reference voltage signals VBS1 to VBS3 in the drive circuit board 101, respectively. Similarly, the drive signal COMB and the reference voltage signal VBS generated by the drive circuit 50b are separated into three drive signals COMB1 to COMB3 and three reference voltage signals VBS1 to VBS3 in the drive circuit board 101, respectively. Similarly, the drive signal COMA and the reference voltage signal VBS generated by the drive circuit 50c are separated into three drive signals COMA4 to COMA6 and three reference voltage signals VBS4 to VBS6 in the drive circuit board 101, respectively. Similarly, the drive signal COMB and the reference voltage signal VBS generated by the drive circuit 50d are separated into three drive signals COMB4 to COMB6 and three reference voltage signals VBS4 to VBS6 in the drive circuit board 101, respectively. The drive signals COMA1 to COMA6 are all signals having the same waveform, the drive signals COMB1 to COMB6 are all signals having the same waveform, and the reference voltage signals VBS1 to VBS6 are all signals having the same waveform.

  Each of the drive signals COMA1 to COMA6 and COMB1 to COMB6 propagates through a plurality (hereinafter, eight) of signal lines on the drive circuit board 101 and further propagates through a plurality of (hereinafter, four) cables 19. It is supplied to the first relay board 102. Further, each of the reference voltage signals VBS1 to VBS6 propagates through a plurality (16 in the following) of signal lines on the drive circuit board 101, and further propagates through a plurality of (in the following, 8) cables 19 to be the first relay. It is supplied to the substrate 102.

  Further, the drive circuit board 101 generates a plurality of signal lines through which the high power supply voltage signal VHV and the ground voltage signal GND supplied from the power supply circuit 112 provided on the control board 100 are propagated, and a voltage conversion circuit 114. And a plurality of signal lines through which the low power supply voltage signal VDD is transmitted. The high power supply voltage signal VHV, the ground voltage signal GND, and the low power supply voltage signal VDD are further propagated through the cable 19 and supplied to the first relay board 102.

  Further, the drive circuit board 101 is provided with a plurality of signal lines through which the temperature signal TH and the abnormality signal XHOT supplied from the first relay board 102 propagate. The temperature signal TH and the abnormal signal XHOT are further propagated through the cable 19 and supplied to the control board 100.

  Drive signals COMA <b> 1 to COMA <b> 6 and COMB <b> 1 to COMB <b> 6 are supplied to the first relay board 102 through the four cables 19 from the drive circuit board 101. Then, each of the drive signals COMA1 to COMA6 and COMB1 to COMB6 propagates eight signal lines on the first relay substrate 102, and then four signal lines obtained by shorting the eight signal lines two by two. And further propagates through the two cables 19 and is supplied to the second relay substrate 103. Reference voltage signals VBS <b> 1 to VBS <b> 6 are supplied to the first relay board 102 from the drive circuit board 101 via the eight cables 19, respectively. Each of the reference voltage signals VBS <b> 1 to VBS <b> 6 propagates 16 signal lines on the first relay substrate 102, and then propagates 8 signal lines in which the 16 signal lines are short-circuited two by two. Further, it propagates through the four cables 19 and is supplied to the second relay substrate 103.

  Further, the first relay substrate 102 is provided with a plurality of signal lines through which the high power supply voltage signal VHV, the ground voltage signal GND, and the low power supply voltage signal VDD supplied from the drive circuit substrate 101 propagate. The high power supply voltage signal VHV, the ground voltage signal GND, and the low power supply voltage signal VDD propagate through the cable 19 and are supplied to each circuit provided on the head substrate 104.

  Further, the first relay substrate 102 is provided with a plurality of signal lines through which the temperature signal TH and the abnormality signal XHOT supplied from the head substrate 104 propagate. The temperature signal TH and the abnormal signal XHOT propagate through the cable 19 and are supplied to the drive circuit board 101.

Drive signals COMA <b> 1 to COMA <b> 6 and COMB <b> 1 to COMB <b> 6 are supplied to the second relay substrate 103 via the two cables 19 from the first relay substrate 102. Then, each of the drive signals COMA1 to COMA6 and COMB1 to COMB6 propagates through the four signal lines on the second relay substrate 103 and then shorts the four signal lines two by two. , Further propagates through one cable 19 and is supplied to the head substrate 104.
Further, the reference voltage signals VBS1 to VBS6 are supplied to the second relay board 103 from the first relay board 102 via the four cables 19, respectively. Each of the reference voltage signals VBS <b> 1 to VBS <b> 6 propagates eight signal lines on the second relay substrate 103, and then propagates four signal lines that are short-circuited by two of the eight signal lines. Further, it propagates through the two cables 19 and is supplied to the head substrate 104.

  Drive signals COMA <b> 1 to COMA <b> 6 and COMB <b> 1 to COMB <b> 6 are supplied to the head substrate 104 from the second relay substrate 103 via one cable 19. Each of the drive signals COMA1 to COMA6 and COMB1 to COMB6 propagates through one signal line in which the two signal lines are short-circuited after propagating through the two signal lines on the head substrate 104. Further, reference voltage signals VBS1 to VBS6 are supplied to the head substrate 104 from the second relay substrate 103 via the two cables 19 respectively. Each of the reference voltage signals VBS <b> 1 to VBS <b> 6 propagates through the four signal lines on the head substrate 104 and then propagates through one signal line in which the four signal lines are short-circuited.

  The head substrate 104 is provided with (mounted on) a control signal receiving unit 115, a temperature detection circuit 116, and six drive signal selection circuits 120a to 120f.

  The control signal receiving unit 115 transmits the differential signals (SI1 +, SI1-) to (SI6 +, SI6-), (LAT +, LAT−), (CH +, CH−) of the LVDS transfer method transmitted from the control signal transmitting unit 113. , (SCK +, SCK−) are received, the received differential signals are differentially amplified, and converted into single-end print data signals SI1 to SI6, a latch signal LAT, a change signal CH, and a clock signal SCK. The control signal receiving unit 115 may receive various high-speed transfer differential signals such as LVPECL and CML other than LVDS.

  The print data signals SI1 to SI6 are supplied to the drive signal selection circuits 120a to 120f, respectively. The latch signal LAT, the change signal CH, and the clock signal SCK are commonly supplied to the drive signal selection circuits 120a to 120f.

  The drive signal selection circuits 120a to 120f output the drive signals VOUT1 to VOUT6 to any of the plurality of ejection units 600 that eject ink from the plurality of nozzles in the head 21, respectively. Specifically, the drive signal selection circuits 120a to 120f are one of the drive signals COMA1 to COMA6 and COMB1 to COMB6 based on the clock signal SCK, the print data signals SI1 to SI6, the latch signal LAT, and the change signal CH, respectively. Are selected and output as drive signals VOUT1 to VOUT6, or none are selected and the output is set to high impedance. The circuit configuration of the drive signal selection circuits 120a to 120f may be the same, and details thereof will be described later.

The drive signal VOUT1 is applied to one end of the piezoelectric element 60 included in each ejection unit 600 provided corresponding to the first nozzle array 650a and the second nozzle array 650b, and a reference voltage signal is applied to the other end of the piezoelectric element 60. VBS1 is applied. Further, the drive signal VOUT2 is applied to one end of the piezoelectric element 60 included in each ejection unit 600 provided corresponding to the third nozzle row 650c and the fourth nozzle row 650d, and the other end of the piezoelectric element 60 has a reference A voltage signal VBS2 is applied. The drive signal VOUT3 is applied to one end of the piezoelectric element 60 included in each ejection unit 600 provided corresponding to the fifth nozzle row 650e and the sixth nozzle row 650f, and the other end of the piezoelectric element 60 has a reference A voltage signal VBS3 is applied. Further, the drive signal VOUT4 is applied to one end of the piezoelectric element 60 included in each ejection unit 600 provided corresponding to the seventh nozzle row 650g and the eighth nozzle row 650h, and the other end of the piezoelectric element 60 has a reference A voltage signal VBS4 is applied. Further, the drive signal VOUT5 is applied to one end of the piezoelectric element 60 included in each ejection unit 600 provided corresponding to the ninth nozzle row 650i and the tenth nozzle row 650j, and the other end of the piezoelectric element 60 has a reference A voltage signal VBS5 is applied. The drive signal VOUT6 is applied to one end of the piezoelectric element 60 included in each of the ejection units 600 provided corresponding to the eleventh nozzle row 650k and the twelfth nozzle row 650l. A voltage signal VBS6 is applied.

  Each piezoelectric element 60 is provided corresponding to each of the ejection units 600 and is displaced by applying drive signals VOUT1 to VOUT6 (drive signals COMA1 to COMA6, COMB1 to COMB6). Each piezoelectric element 60 is displaced in accordance with the potential difference between the drive signals VOUT1 to VOUT6 (drive signals COMA1 to COMA6, COMB1 to COMB6) and the reference voltage signals VBS1 to VBS6 to discharge liquid (ink). As described above, the drive signals COMA1 to COMA6 and COMB1 to COMB6 are signals for driving each of the ejection units 600 to eject the liquid, and the head unit 20 (head 21) receives the drive signals COMA1 to COMA6 and COMB1 to COMB1. Liquid (ink) is ejected according to COMB6.

  At this time, the ejection characteristics change depending on the temperature characteristics of the piezoelectric element 60, and as a result, the liquid ejection accuracy is affected. Therefore, the temperature detection circuit 116 detects the temperature of the head unit 20 (head 21, head substrate 104) by a temperature sensor (not shown), and outputs a temperature signal TH that is an analog signal including temperature information of the head unit 20. . Further, the temperature detection circuit 116 compares the voltage value of the temperature signal TH with a predetermined threshold (a voltage value corresponding to a temperature at which an abnormality in ink ejection may occur) to indicate an abnormality in the head unit 20 (for example, too high temperature). An abnormal signal XHOT that is a digital signal is output. That is, if the abnormal signal XHOT is active (for example, high level), it indicates that it is abnormal. The temperature signal TH and the abnormal signal XHOT propagate through the cable 19 and are supplied to the first relay board 102. As described above, the temperature signal TH and the abnormality signal XHOT are further supplied to the control unit 111 provided on the control board 100 via the drive circuit board 101, and the control unit 111 is supplied from the drive circuit board 101. Various processes are performed according to the temperature signal TH and the abnormal signal XHOT. As a result, it is possible to improve the accuracy of ink ejection from the ejection unit 600 and to prevent an abnormal operation or failure of the head unit 20 (head 21, head substrate 104).

  Since the drive signals COMA (COMA1 to COMA6) and COMB (COMB1 to COMB6) are signals for driving the ejection unit 600, they are high voltage signals (several tens of volts) and are used to generate the drive signals COMA and COMB. The circuits 50a to 50d have large power consumption and are likely to become high temperature. In addition, when the waveforms of the drive signals COMA and COMB change according to the temperature characteristics of the drive circuits 50a to 50d, the liquid ejection accuracy from the ejection unit 600 is affected. Therefore, a temperature sensor is provided in the vicinity of the drive circuits 50a to 50d in the drive circuit board 101, and the control unit 111 receives the output signal of the temperature sensor via the cable 19, and outputs the output signal and temperature of the temperature sensor. Based on the signal TH, the drive data COMA_D0 and COMA_D1 and the drive data COMB_D0 and COMB_D1 may be generated so that the waveforms of the drive signals COMA and COMB are temperature-corrected.

3. Configuration of Discharge Unit FIG. 5 is a diagram illustrating a schematic configuration corresponding to one discharge unit 600 included in the head 21. As shown in FIG. 5, the head 21 includes a discharge unit 600 and a reservoir 641.

  The reservoir 641 is provided for each ink color, and the ink is introduced into the reservoir 641 from the supply port 661. Ink is supplied from the ink reservoir 8 to the supply port 661 through the ink tube 9.

  The discharge unit 600 includes a piezoelectric element 60, a vibration plate 621, a cavity (pressure chamber) 631, and a nozzle 651. Among these, the diaphragm 621 functions as a diaphragm that is displaced (bending vibration) by the piezoelectric element 60 provided on the upper surface in the drawing, and expands / reduces the internal volume of the cavity 631 filled with ink. The nozzle 651 is an opening provided in the nozzle plate 632 and communicating with the cavity 631. The cavity 631 is filled with a liquid (for example, ink), and the internal volume changes due to the displacement of the piezoelectric element 60. The nozzle 651 communicates with the cavity 631 and discharges the liquid in the cavity 631 as droplets according to the change in the internal volume of the cavity 631.

  A piezoelectric element 60 shown in FIG. 5 has a structure in which a piezoelectric body 601 is sandwiched between a pair of electrodes 611 and 612. In the piezoelectric body 601 having this structure, the central portion in FIG. 5 is bent vertically with respect to both end portions together with the electrodes 611 and 612 and the diaphragm 621 in accordance with the voltage applied by the electrodes 611 and 612. Specifically, the piezoelectric element 60 bends upward when the voltage of the drive signal VOUT (any one of the drive signals VOUT1 to VOUT6) increases, while it bends downward when the voltage of the drive signal VOUT decreases. It has a configuration. In this configuration, if the ink is bent upward, the internal volume of the cavity 631 is expanded. Therefore, if the ink is drawn from the reservoir 641, if the ink is bent downward, the internal volume of the cavity 631 is reduced. Depending on the degree, the ink is ejected from the nozzle 651.

  The piezoelectric element 60 is not limited to the illustrated structure, and may be any type that can deform the piezoelectric element 60 and discharge a liquid such as ink. Further, the piezoelectric element 60 is not limited to bending vibration, and may be configured to use so-called longitudinal vibration.

  The piezoelectric element 60 is provided in the head 21 corresponding to the cavity 631 and the nozzle 651, and is also provided corresponding to the selection unit 230 (see FIG. 8) described later. For this reason, a set of the piezoelectric element 60, the cavity 631, the nozzle 651, and the selection unit 230 is provided for each nozzle 651.

4). Structure of drive signal As a method of forming dots on the print medium P, in addition to a method of forming one dot by ejecting ink droplets once, it is possible to eject ink droplets twice or more in a unit period. A method of forming one dot by landing one or more ink droplets ejected during a period and combining the one or more ink droplets that have landed (second method), or combining these two or more ink droplets There is a method (third method) for forming two or more dots without causing them to occur.

  In the present embodiment, by the second method, “large dot”, “medium dot”, “small dot”, and “non-recording (no dot)” are performed by ejecting ink twice at most for one dot. 4 gradations are expressed. In order to express these four gradations, in this embodiment, two types of drive signals COMA (COMA1 to COMA6) and COMB (COMB1 to COMB6) are prepared, and in each case, the first half pattern and the second half pattern Is given. In the first half and the second half of one cycle, the drive signal COMOMAMB is selected according to the gradation to be expressed (or not selected) and supplied to the piezoelectric element 60.

  FIG. 6 is a diagram illustrating waveforms of the drive signals COMA and COMB. As shown in FIG. 6, the drive signal COMA includes a trapezoidal waveform Adp1 arranged in a period T1 from when the latch signal LAT rises to when the change signal CH rises, and the latch signal LAT after the change signal CH rises. It is a waveform that is continuous with the trapezoidal waveform Adp2 arranged in the period T2 until the rise. A period composed of the period T1 and the period T2 is defined as a period Ta, and a new dot is formed on the print medium P every period Ta.

  In the present embodiment, the trapezoidal waveforms Adp1 and Adp2 are substantially the same waveforms, and if each is supplied to one end of the piezoelectric element 60, a predetermined amount from the nozzle 651 corresponding to the piezoelectric element 60, Specifically, it is a waveform for ejecting a medium amount of ink.

  The drive signal COMB has a waveform in which the trapezoidal waveform Bdp1 arranged in the period T1 and the trapezoidal waveform Bdp2 arranged in the period T2 are continuous. In the present embodiment, the trapezoidal waveforms Bdp1 and Bdp2 are different from each other. Among these, the trapezoidal waveform Bdp1 is a waveform for causing the ink near the opening of the nozzle 651 to vibrate and preventing the viscosity of the ink from increasing. For this reason, even if the trapezoidal waveform Bdp1 is supplied to one end of the piezoelectric element 60, ink droplets are not ejected from the nozzle 651 corresponding to the piezoelectric element 60. The trapezoidal waveform Bdp2 is different from the trapezoidal waveform Adp1 (Adp2). If the trapezoidal waveform Bdp2 is supplied to one end of the piezoelectric element 60, it is a waveform that causes an amount of ink smaller than the predetermined amount to be ejected from the nozzle 651 corresponding to the piezoelectric element 60.

  The voltage at the start timing and the voltage at the end timing of the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2 are all the same as the voltage Vc. That is, the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2 are waveforms that start at the voltage Vc and end at the voltage Vc, respectively.

  FIG. 7 is a diagram illustrating waveforms of the drive signals VOUT (VOUT1 to VOUT6) corresponding to “large dots”, “medium dots”, “small dots”, and “non-recording”.

  As shown in FIG. 7, the drive signal VOUT corresponding to the “large dot” has a waveform in which the trapezoidal waveform Adp1 of the drive signal COMA in the period T1 and the trapezoidal waveform Adp2 of the drive signal COMA in the period T2 are continuous. Yes. When this drive signal VOUT is supplied to one end of the piezoelectric element 60, a medium amount of ink is ejected in two from the nozzle 651 corresponding to the piezoelectric element 60 in the period Ta. For this reason, the respective inks land on the print medium P and coalesce to form large dots.

  The drive signal VOUT corresponding to “medium dot” has a waveform in which the trapezoidal waveform Adp1 of the drive signal COMA in the period T1 and the trapezoidal waveform Bdp2 of the drive signal COMB in the period T2 are continuous. When this drive signal VOUT is supplied to one end of the piezoelectric element 60, medium and small amounts of ink are ejected in two from the nozzle 651 corresponding to the piezoelectric element 60 in the period Ta. For this reason, the respective inks land on the print medium P and combine to form medium dots.

  The drive signal VOUT corresponding to “small dot” is the voltage Vc immediately before being held by the capacitive property of the piezoelectric element 60 in the period T1, and the trapezoidal waveform Bdp2 of the drive signal COMB in the period T2. When the drive signal VOUT is supplied to one end of the piezoelectric element 60, a small amount of ink is ejected from the nozzle 651 corresponding to the piezoelectric element 60 only in the period T2 in the period Ta. For this reason, this ink lands on the print medium P, and small dots are formed.

  The drive signal VOUT corresponding to “non-recording” is a trapezoidal waveform Bdp1 of the drive signal COMB in the period T1, and is the voltage Vc just before being held by the capacitance of the piezoelectric element 60 in the period T2. When this drive signal VOUT is supplied to one end of the piezoelectric element 60, the nozzle 651 corresponding to the piezoelectric element 60 only slightly vibrates in the period T2, and ink is not ejected in the period Ta. For this reason, ink does not land on the print medium P, and no dots are formed.

5. Configuration of Drive Signal Selection Circuit FIG. 8 is a diagram illustrating the configuration of the drive signal selection circuit 120 (120a to 120f). As shown in FIG. 8, the drive signal selection circuit 120 includes a selection control unit 220 and a plurality of selection units 230.

  The selection control unit 220 is supplied with a clock signal SCK, a print data signal SI, a latch signal LAT, and a change signal CH. In the selection control unit 220, a set of a shift register (S / R) 222, a latch circuit 224, and a decoder 226 is provided corresponding to each of the piezoelectric elements 60 (nozzles 651). That is, the number of sets of the shift register (S / R) 222, the latch circuit 224, and the decoder 226 included in one drive signal selection circuit 120 is the same as the total number m of the nozzles 651 included in the two nozzle rows 650. .

  The print data signal SI is used to select any one of “large dots”, “medium dots”, “small dots”, and “non-recording” for each of the m ejection portions 600 (piezoelectric elements 60). This is a signal of 2 m bits in total including 2-bit print data (SIH, SIL).

  The print data signal SI is a signal that is synchronized with the clock signal SCK, and is configured to temporarily hold each 2-bit print data (SIH, SIL) included in the print data signal SI corresponding to the nozzle 651. Is the shift register 222.

  Specifically, the shift registers 222 having the number of stages corresponding to the piezoelectric elements 60 (nozzles 651) are cascade-connected to each other, and the serially supplied print data signal SI is sequentially transferred to the subsequent stage according to the clock signal SCK. It has become.

  In order to distinguish the shift register 222, the first stage, the second stage,..., And the m stage are shown in order from the upstream side to which the print data signal SI is supplied.

  Each of the m latch circuits 224 latches the 2-bit print data (SIH, SIL) held in each of the m shift registers 222 at the rising edge of the latch signal LAT.

  Each of the m decoders 226 decodes 2-bit print data (SIH, SIL) latched by each of the m latch circuits 224, and has a period T1 defined by the latch signal LAT and the change signal CH. , The selection signals Sa and Sb are output every T2, and the selection by the selection unit 230 is defined.

  FIG. 9 is a diagram showing the decoded contents in the decoder 226. For example, if the latched 2-bit print data (SIH, SIL) is (1, 0), the decoder 226 sets the logic levels of the selection signals Sa and Sb to the H and L levels in the period T1, respectively, and the period T2 Means output as the L and H levels, respectively.

  Note that the logic levels of the selection signals Sa and Sb are shifted to higher amplitude logic by a level shifter (not shown) than the logic levels of the clock signal SCK, the print data signal SI, the latch signal LAT, and the change signal CH. The

  The selection unit 230 is provided corresponding to each of the piezoelectric elements 60 (nozzles 651). That is, the number of selection units 230 included in one drive signal selection circuit 120 is the same as the total number m of nozzles 651 included in the two nozzle rows 650.

  FIG. 10 is a diagram illustrating a configuration of the selection unit 230 corresponding to one piezoelectric element 60 (nozzle 651).

  As shown in FIG. 10, the selection unit 230 includes inverters (NOT circuits) 232a and 232b and transfer gates 234a and 234b.

  The selection signal Sa from the decoder 226 is supplied to a positive control terminal that is not circled in the transfer gate 234a, while being logically inverted by the inverter 232a and negatively controlled in the transfer gate 234a. Supplied to the end. Similarly, the selection signal Sb is supplied to the positive control terminal of the transfer gate 234b, while logically inverted by the inverter 232b and supplied to the negative control terminal of the transfer gate 234b.

  The drive signal COMA is supplied to the input terminal of the transfer gate 234a, and the drive signal COMB is supplied to the input terminal of the transfer gate 234b. The output terminals of the transfer gates 234a and 234b are connected in common, and the drive signal VOUT is output to the ejection unit 600 via the common connection terminal.

  When the selection signal Sa is at the H level, the transfer gate 234a conducts (turns on) between the input end and the output end, and when the selection signal Sa is at the L level, the transfer gate 234a does not conduct between the input end and the output end. (Off). Similarly, the transfer gate 234b is turned on / off between the input end and the output end according to the selection signal Sb.

  Next, the operation of the drive signal selection circuit 120 (120a to 120f) will be described with reference to FIG.

  The print data signal SI (any one of the print data signals SI1 to SI6) is serially supplied in synchronization with the clock signal SCK and sequentially transferred in the shift register 222 corresponding to the nozzle. When the supply of the clock signal SCK is stopped, the shift register 222 is in a state where the 2-bit print data (SIH, SIL) corresponding to the nozzle 651 is held. The print data signal SI is supplied in the order corresponding to the last m stages,..., Two stages, and one stage nozzles in the shift register 222.

  Here, when the latch signal LAT rises, each of the latch circuits 224 latches the 2-bit print data (SIH, SIL) held in the shift register 222 at the same time. In FIG. 11, LT1, LT2,..., LTm indicate 2-bit print data (SIH, SIL) latched by the latch circuit 224 corresponding to the 1-stage, 2-stage,. Yes.

  The decoder 226 shows the logic levels of the selection signals Sa and Sb in each of the periods T1 and T2 in accordance with the dot size defined by the latched 2-bit print data (SIH, SIL), as shown in FIG. The output is as follows.

That is, when the print data (SIH, SIL) is (1, 1) and the size of the large dot is defined, the decoder 226 sets the selection signals Sa and Sb to the H and L levels in the period T1, and the period At T2, the H and L levels are set. Further, when the print data (SIH, SIL) is (1, 0) and the size of the medium dot is defined, the decoder 226 sets the selection signals Sa and Sb to the H and L levels in the period T1, and the period At T2, L and H levels are set. Further, when the print data (SIH, SIL) is (0, 1) and the size of the small dot is specified, the decoder 226 sets the selection signals Sa and Sb to the L and L levels in the period T1, and the period At T2, L and H levels are set. When the print data (SIH, SIL) is (0, 0) and non-recording is specified, the decoder 226 sets the selection signals Sa and Sb to the L and H levels in the period T1, and in the period T2. L and L level.

  When the print data (SIH, SIL) is (1, 1), the selection unit 230 selects the drive signal COMA (trapezoidal waveform Adp1) because the selection signals Sa and Sb are at the H and L levels in the period T1. Even at T2, since Sa and Sb are at the H and L levels, the drive signal COMA (trapezoidal waveform Adp2) is selected. As a result, the drive signal VOUT corresponding to the “large dot” shown in FIG. 7 is generated.

  Further, when the print data (SIH, SIL) is (1, 0), the selection unit 230 selects the drive signal COMA (trapezoidal waveform Adp1) because the selection signals Sa and Sb are at the H and L levels in the period T1. In the period T2, since Sa and Sb are at the L and H levels, the drive signal COMB (trapezoid waveform Bdp2) is selected. As a result, the drive signal VOUT corresponding to the “medium dot” shown in FIG. 7 is generated.

  In addition, when the print data (SIH, SIL) is (0, 1), the selection unit 230 does not select any of the drive signals COMA and COMB because the selection signals Sa and Sb are at the L and L levels in the period T1. In the period T2, since Sa and Sb are at the L and H levels, the drive signal COMB (trapezoid waveform Bdp2) is selected. As a result, the drive signal VOUT corresponding to the “small dot” shown in FIG. 7 is generated. Note that since neither the drive signal COMA nor COMB is selected during the period T1, one end of the piezoelectric element 60 is opened. However, the drive signal VOUT is held at the immediately preceding voltage Vc due to the capacitance of the piezoelectric element 60. .

  Further, when the print data (SIH, SIL) is (0, 0), the selection unit 230 selects the drive signal COMB (trapezoidal waveform Bdp1) because the selection signals Sa and Sb are at the L and H levels in the period T1. In the period T2, since the selection signals Sa and Sb are at the L and L levels, none of the drive signals COMA and COMB is selected. As a result, the drive signal VOUT corresponding to “non-recording” shown in FIG. 7 is generated. Note that in the period T2, since neither the drive signal COMA nor COMB is selected, one end of the piezoelectric element 60 is opened, but the drive signal VOUT is held at the immediately preceding voltage Vc due to the capacitance of the piezoelectric element 60. .

  Note that the drive signals COMA and COMB shown in FIGS. 6 and 11 are merely examples. Actually, various combinations of waveforms prepared in advance are used according to the moving speed of the head unit 20 and the properties of the print medium P.

  Further, here, the example in which the piezoelectric element 60 bends upward as the voltage increases has been described. However, when the voltage supplied to the electrodes 611 and 612 is reversed, the piezoelectric element 60 increases as the voltage increases. Will bend downward. For this reason, in the configuration in which the piezoelectric element 60 bends downward as the voltage increases, the drive signals COMA and COMB illustrated in FIGS. 6 and 11 have waveforms that are inverted with respect to the voltage Vc.

6). Configuration of Drive Circuit Next, the drive circuits 50a to 50d will be described. Of these, the drive circuits 50a and 50c are summarized as follows. The drive signal COMA is generated as follows. That is, the drive circuits 50a and 50c first integrate the 2-bit drive data COMA_D0 and COMA_D1, convert the integrated data to analog, and secondly feed back the output drive signal COMA and also output the drive signal. The deviation between the signal based on the COMA (attenuation signal) and the target signal is corrected with the high frequency component of the drive signal COMA, and a modulation signal is generated according to the corrected signal. Third, the transistor is switched according to the modulation signal As a result, an amplified modulated signal is generated, and fourthly, the amplified modulated signal is smoothed (demodulated) with a low-pass filter, and the smoothed signal is output as the drive signal COMA.

  The drive circuits 50b and 50d have the same configuration, and differ only in that the drive signal COMB is output from the 2-bit drive data COMB_D0 and COMB_D1. Therefore, in FIG. 12 below, the drive circuits 50a to 50d will be described as the drive circuit 50 without distinction.

  FIG. 12 is a diagram illustrating a circuit configuration of the drive circuit 50. As shown in FIG. 12, the drive circuit 50 includes an integrated circuit device 500, an output circuit 550, a first feedback circuit 570, and a second feedback circuit 572.

  The integrated circuit device 500 applies gate signals (amplification control) to each of the first transistor M1 and the second transistor M2 based on 2-bit drive data COMA_D0 and COMA_D1 (COMB_D0 and COMB_D1) input via the terminals In1 and In2. Signal). Therefore, the integrated circuit device 500 includes an integrating unit 501, a DAC (Digital to Analog Converter) 511, an adder 512, an adder 513, a comparator 514, an integral attenuator 516, an attenuator 517, and an inverter 515. A first gate driver 521, a second gate driver 522, a first power supply unit 530, and a reference voltage generation unit 580. The integrated circuit device 500 includes a first power supply unit 530.

  The reference voltage generation unit 580 generates a first reference voltage DAC_HV (high voltage side reference voltage) and a second reference voltage DAC_LV (low voltage side reference voltage), and supplies the generated voltage to the DAC 511.

  The accumulating unit 501 accumulates 2-bit drive data COMA_D0 and COMA_D1 (COMB_D0, COMB_D1), and supplies the accumulated k-bit data (drive data dA (dB)) to the DAC 511.

  The DAC 511 converts the k-bit drive data dA (dB) that defines the waveform of the drive signal COMA into an original drive signal Aa of a voltage between the first reference voltage DAC_HV and the second reference voltage DAC_LV, and the adder 512 To the input terminal (+). The maximum amplitude and the minimum value of the original drive signal Aa are determined by the first reference voltage DAC_HV and the second reference voltage DAC_LV (for example, about 1 to 2 V), and the amplified voltage is used to drive the original drive signal Aa. Signal COMA. That is, the original drive signal Aa is a target signal before the drive signal COMA is amplified.

  The integral attenuator 516 attenuates the voltage of the terminal Out input through the terminal Vfb, that is, the drive signal COMA, integrates it, and supplies it to the input terminal (−) of the adder 512.

  The adder 512 supplies a voltage signal Ab obtained by subtracting the voltage at the input terminal (−) from the voltage at the input terminal (+) to the input terminal (+) of the adder 513.

  Note that the power supply voltage of the circuit from the DAC 511 to the inverter 515 is, for example, low amplitude 3.3 V (the voltage of the low power supply voltage signal VDD supplied from the voltage conversion circuit 114 (see FIG. 4)). For this reason, while the voltage of the original drive signal Aa is about 2V at the maximum, the voltage of the drive signal COMA may exceed 40V at the maximum. The voltage of the signal COMA is attenuated by the integral attenuator 516.

  The attenuator 517 attenuates the high frequency component of the drive signal COMA input via the terminal Ifb and supplies the attenuated high frequency component to the input terminal (−) of the adder 513. The adder 513 supplies a voltage signal As obtained by subtracting the voltage at the input terminal (−) from the voltage at the input terminal (+) to the comparator 514. The function of the attenuator 517 is adjustment of modulation gain (sensitivity). That is, the frequency and duty ratio of the modulation signal Ms change in accordance with the drive data dA (dB), but the attenuator 517 adjusts these changes.

  The voltage of the signal As output from the adder 513 is a voltage obtained by subtracting the attenuation voltage of the signal supplied to the terminal Ifb from the voltage of the original drive signal Aa by subtracting the attenuation voltage of the signal supplied to the terminal Vfb. is there. For this reason, the voltage of the signal As by the adder 513 is obtained by subtracting the deviation obtained by subtracting the attenuation voltage of the drive signal COMA (COMB) output from the terminal Out from the target voltage of the original drive signal Aa. It can be said that the signal is corrected with the high frequency component of (COMB).

  The comparator 514 outputs a modulation signal Ms that is pulse-modulated as follows based on the subtraction voltage from the adder 513. Specifically, the comparator 514 is at the H level when the signal As output from the adder 513 is at a voltage rise, when the signal As becomes equal to or higher than the voltage threshold Vth1, and when the signal As is at the voltage fall, A modulation signal Ms that becomes L level when it falls below the threshold value Vth2 is output. As will be described later, the voltage threshold is set to have a relationship of Vth1> Vth2.

  The modulation signal Ms from the comparator 514 is supplied to the second gate driver 522 through logic inversion by the inverter 515. On the other hand, the modulation signal Ms is supplied to the first gate driver 521 without undergoing logic inversion. For this reason, the logic levels supplied to the first gate driver 521 and the second gate driver 522 are mutually exclusive.

  The logic levels supplied to the first gate driver 521 and the second gate driver 522 are actually timings so that they are not simultaneously at the H level (so that the first transistor M1 and the second transistor M2 are not turned on simultaneously). You may control. Therefore, strictly speaking, exclusive here means that they are not simultaneously at the H level (the first transistor M1 and the second transistor M2 are not simultaneously turned on).

  By the way, the modulation signal here is the modulation signal Ms in a narrow sense, but if it is considered that the signal is pulse-modulated according to the original drive signal Aa, a negative signal of the modulation signal Ms is also included in the modulation signal. That is, the modulation signal pulse-modulated according to the original drive signal Aa includes not only the modulation signal Ms but also a signal obtained by inverting the logic level of the modulation signal Ms and a signal whose timing is controlled.

  Note that the adder 512, the adder 513, the comparator 514, the inverter 515, the integral attenuator 516, and the attenuator 517 modulate the original drive signal Aa to generate the modulation signal Ms. Function as.

The first gate driver 521 level-shifts the low logic amplitude, which is the output signal of the comparator 514, to a high logic amplitude and outputs the result from the terminal Hdr. Of the power supply voltage of the first gate driver 521, the higher side is a voltage applied via the terminal Bst, and the lower side is a voltage applied via the terminal Sw. The terminal Bst is connected to one end of the capacitor C5 and the cathode electrode of the backflow preventing diode D1. The terminal Sw is connected to the source electrode in the first transistor M1, the drain electrode in the second transistor M2, the other end of the capacitor C5, and one end of the inductor L1. The anode electrode of the diode D1 is connected to one end of the terminal Gvd, and the voltage Vm (for example, 7.5 V) of the power supply voltage signal GVDD supplied from the voltage conversion circuit 114 (see FIG. 4) is applied. Therefore, the potential difference between the terminal Bst and the terminal Sw is approximately equal to the potential difference between both ends of the capacitor C5, that is, the voltage Vm (for example, 7.5 V).

  The second gate driver 522 operates on the lower potential side than the first gate driver 521. The second gate driver 522 levels the low logic amplitude (L level: 0 V, H level: 3.3 V), which is the output signal of the inverter 515, to a high logic amplitude (for example, L level: 0 V, H level: 7.5 V). Shift and output from terminal Ldr. Among the power supply voltages of the second gate driver 522, the voltage Vm (for example, 7.5V) is applied as the high-order side, and the ground supplied from the power supply circuit 112 (see FIG. 4) via the ground terminal Gnd as the low-order side. The voltage (0 V) of the voltage signal GND is applied (the lower power supply terminal is grounded).

  The first transistor M1 and the second transistor M2 are, for example, N-channel FETs (Field Effect Transistors). Among these, in the first transistor M1 on the high side, the voltage Vh (for example, 42V) of the high power supply voltage signal VHV supplied from the voltage conversion circuit 114 (see FIG. 4) is applied to the drain electrode, and the gate electrode is The resistor H1 is connected to the terminal Hdr. For the low-side second transistor M2, the gate electrode is connected to the terminal Ldr via the resistor R2, and the source electrode is grounded.

  Therefore, when the first transistor M1 is off and the second transistor M2 is on, the voltage at the terminal Sw is 0V, and the voltage Vm (for example, 7.5V) is applied to the terminal Bst. On the other hand, when the first transistor M1 is on and the second transistor M2 is off, a voltage Vh (for example, 42V) is applied to the terminal Sw, and a voltage Vh + Vm (for example, 49.5V) is applied to the terminal Bst.

  That is, the first gate driver 521 uses the capacitor C5 as a floating power supply, and the reference potential (the potential of the terminal Sw) changes to 0 V or a voltage Vh (for example, 42 V) according to the operation of the first transistor M1 and the second transistor M2. Therefore, the amplification control when the L level is near 0 V and the H level is near the voltage Vm (for example, 7.5 V), or the L level is near the voltage Vh (for example, 42 V) and the H level is near the voltage Vh + Vm (for example, 49.5 V). Output a signal. On the other hand, in the second gate driver 522, the reference potential (the potential of the ground terminal Gnd) is fixed to 0V regardless of the operations of the first transistor M1 and the second transistor M2, and therefore the L level is near 0V and An amplification control signal whose H level is near the voltage Vm (for example, 7.5 V) is output.

  The first gate driver 521 and the second gate driver 522 function as a gate driver 520 that generates an amplification control signal based on the modulation signal Ms. The first transistor M1 and the second transistor M2 function as an amplifier circuit that generates an amplified modulation signal obtained by amplifying the modulation signal Ms.

  The other end of the inductor L1 is a terminal Out that is an output in the drive circuit 50, and a drive signal COMA (COMB) is supplied from the terminal Out to each of the selection units 230.

The terminal Out is connected to one end of the capacitor C1, one end of the capacitor C2, and one end of the resistor R3. Among these, the other end of the capacitor C1 is grounded. Therefore, the inductor L1 and the capacitor C1 are a low pass filter (Low Pass Filter) 560 that smoothes (demodulates) the amplified modulation signal appearing at the connection point between the first transistor M1 and the second transistor M2 to generate a drive signal. Function as.

  The other end of the resistor R3 is connected to the terminal Vfb and one end of the resistor R4, and the voltage Vh is applied to the other end of the resistor R4. As a result, the drive signal COMA that has passed through the first feedback circuit 570 (the circuit configured by the resistors R3 and R4) is pulled up and fed back to the terminal Vfb.

  On the other hand, the other end of the capacitor C2 is connected to one end of the resistor R5 and one end of the resistor R6. Among these, the other end of the resistor R5 is grounded. For this reason, the capacitor C2 and the resistor R5 function as a high pass filter that passes a high frequency component equal to or higher than the cutoff frequency in the drive signal COMA (COMB) from the terminal Out. Note that the cutoff frequency of the high-pass filter is set to about 9 MHz, for example.

  The other end of the resistor R6 is connected to one end of the capacitor C4 and one end of the capacitor C3. Among these, the other end of the capacitor C3 is grounded. For this reason, the resistor R6 and the capacitor C3 function as a low-pass filter that passes a low-frequency component having a frequency equal to or lower than the cutoff frequency among signal components that have passed through the high-pass filter. Note that the cutoff frequency of the LPF is set to about 160 MHz, for example.

  Since the cut-off frequency of the high-pass filter is set lower than the cut-off frequency of the low-pass filter, the high-pass filter and the low-pass filter pass a high-frequency component in a predetermined frequency range in the drive signal COMA. It functions as a pass filter.

  The other end of the capacitor C4 is connected to the terminal Ifb of the integrated circuit device 500. As a result, the terminal Ifb has a high-frequency component of the drive signal COMA that has passed through the second feedback circuit 572 (a circuit composed of the capacitor C2, the resistor R5, the resistor R6, the capacitor C3, and the capacitor C4) that functions as the bandpass filter. Among them, the direct current component is cut and returned.

  By the way, the drive signal COMA (COMB) output from the terminal Out smooths the amplified modulation signal at the connection point (terminal Sw) between the first transistor M1 and the second transistor M2 by a low-pass filter including the inductor L1 and the capacitor C1. Signal. This drive signal COMA (COMB) is integrated / subtracted via the terminal Vfb and then fed back to the adder 512. Therefore, the feedback delay (the delay due to the smoothing of the inductor L1 and the capacitor C1 and the integral attenuator). Self-oscillation at a frequency determined by the transfer function of feedback).

  However, since the delay amount of the feedback path via the terminal Vfb is large, the frequency of the self-excited oscillation can be sufficiently secured with sufficient accuracy of the drive signal COMA (COMB) only by the feedback via the terminal Vfb. There are cases where it cannot be raised.

  Therefore, in this embodiment, by providing a path for returning the high-frequency component of the drive signal COMA (COMB) via the terminal Ifb, in addition to the path via the terminal Vfb, the delay when viewed in the entire circuit is reduced. doing. For this reason, the frequency of the signal As obtained by adding the high-frequency component of the drive signal COMA to the signal Ab can sufficiently ensure the accuracy of the drive signal COMA (COMB) compared to the case where there is no path through the terminal Ifb. It gets higher.

  FIG. 13 is a diagram illustrating the waveforms of the signal As and the modulation signal Ms in association with the waveform of the original drive signal Aa.

  As shown in FIG. 13, the signal As is a triangular wave, and its oscillation frequency varies according to the voltage (input voltage) of the original drive signal Aa. Specifically, it is highest when the input voltage is an intermediate value, and decreases as the input voltage increases from the intermediate value or decreases.

  In addition, the slope of the triangular wave in the signal As is approximately equal between the rise (voltage rise) and the fall (voltage drop) when the input voltage is near the intermediate value. For this reason, the duty ratio of the modulation signal Ms, which is the result of comparing the signal As with the voltage thresholds Vth1 and Vth2 by the comparator 514, is approximately 50%. When the input voltage increases from the intermediate value, the downward slope of the signal As becomes gentle. For this reason, the period during which the modulation signal Ms is at the H level is relatively long, and the duty ratio is increased. On the other hand, as the input voltage becomes lower from the intermediate value, the upward slope of the signal As becomes gentler. For this reason, the period during which the modulation signal Ms is at the H level becomes relatively short, and the duty ratio becomes small.

  Therefore, the modulation signal Ms is a pulse density modulation signal as follows. That is, the duty ratio of the modulation signal Ms is approximately 50% at the intermediate value of the input voltage, and increases as the input voltage becomes higher than the intermediate value, and decreases as the input voltage becomes lower than the intermediate value.

  The first gate driver 521 turns on / off the first transistor M1 based on the modulation signal Ms. That is, the first gate driver 521 turns on the first transistor M1 if the modulation signal Ms is at the H level, and turns off the first transistor M1 if the modulation signal Ms is the L level. The second gate driver 522 turns on / off the second transistor M2 based on the logic inversion signal of the modulation signal Ms. In other words, the second gate driver 522 turns off the second transistor M2 when the modulation signal Ms is at the H level, and turns on when the modulation signal Ms is at the L level.

  Therefore, the voltage of the drive signal COMA (COMB) obtained by smoothing the amplified modulated signal at the connection point between the first transistor M1 and the second transistor M2 by the inductor L1 and the capacitor C1 increases as the duty ratio of the modulated signal Ms increases. As the duty ratio becomes smaller, the drive signal COMA (COMB) is controlled and output so as to be a signal obtained by expanding the voltage of the original drive signal Aa.

  Since this drive circuit 50 uses pulse density modulation, there is an advantage that a change width of the duty ratio can be increased as compared with pulse width modulation in which the modulation frequency is fixed.

  That is, since the minimum positive pulse width and negative pulse width that can be handled by the entire circuit are limited by the circuit characteristics, in the pulse width modulation with a fixed frequency, the duty ratio change width is within a predetermined range (for example, from 10%). Only 90%). On the other hand, in pulse density modulation, the oscillation frequency decreases as the input voltage moves away from the intermediate value. Therefore, the duty ratio can be increased in a region where the input voltage is high, and the region where the input voltage is low. In, the duty ratio can be further reduced. For this reason, in the self-excited oscillation type pulse density modulation, a wider range (for example, a range from 5% to 95%) can be secured as a change width of the duty ratio.

The drive circuit 50 is a self-excited oscillation circuit that includes a signal path through which the drive signal COMA (COMB), the modulation signal Ms, and the amplified modulation signal propagate, and is a self-excited oscillation circuit. Is not required. For this reason, there is an advantage that integration other than a circuit that handles high voltage, that is, a portion of the integrated circuit device 500 is easy.

  In addition, in the drive circuit 50, as a feedback path of the drive signal COMA (COMB), not only a path via the terminal Vfb but also a path for feeding back a high frequency component via the terminal Ifb, Delay is reduced. For this reason, since the frequency of self-excited oscillation becomes high, the drive circuit 50 can generate the drive signal COMA (COMB) with high accuracy.

  Returning to FIG. 12, in the example shown in FIG. 12, the resistor R1, the resistor R2, the first transistor M1, the second transistor M2, the capacitor C5, the diode D1, and the low-pass filter 560 generate an amplification control signal based on the modulation signal. The output circuit 550 generates a drive signal COMA (COMB) based on the amplification control signal and outputs the drive signal COMA to the capacitive load (piezoelectric element 60).

  The first power supply unit 530 applies a signal to a terminal different from the terminal to which the drive signal VOUT of the piezoelectric element 60 is applied. The first power supply unit 530 is configured by a constant voltage circuit such as a band gap reference circuit, for example. The first power supply unit 530 outputs a reference voltage signal VBS having a constant voltage (for example, 6V) from the terminal Vbs. The first power supply unit 530 generates the reference voltage signal VBS with reference to the ground potential of the ground terminal Gnd.

7). Next, referring to FIG. 14, the control board 100, the drive circuit board 101, the first relay board 102, the second relay board 103, the head board 104, and the plurality of cables 19 (19a to 19t) are used. The connection relationship will be described. In FIG. 14, the relative positional relationship between the boards, the length of each cable 19, and the position and orientation of the connector are different from the actual ones.

  As shown in FIG. 14, the control board 100 is provided with four connectors 10a to 10d. The connector 10a is connected to the first end of the cable 19a, the connector 10b is connected to the first end of the cable 19b, the connector 10c is connected to the first end of the cable 19c, and the connector 10d is connected to the first end of the cable 19d. One end is connected.

  The drive circuit board 101 (an example of “second board”) is provided with twelve connectors 11a to 11l. The connector 11a is connected to the second end of the cable 19a, the connector 11b is connected to the second end of the cable 19b, and the connector 11c is connected to the second end of the cable 19c. The connector 11d (an example of “fourth connector”) is connected to the first end (an example of “the other end of the second cable”) of the cable 19e (an example of the “second cable”). The first end of the cable 19f is connected, the first end of the cable 19g is connected to the connector 11f, the first end of the cable 19h is connected to the connector 11g, and the first end of the cable 19i is connected to the connector 11h. The connector 11i is connected to the first end of the cable 19j, the connector 11j is connected to the first end of the cable 19k, the connector 11k is connected to the first end of the cable 19l, and the connector 11l is connected to the cable 19m. The 1st end of is connected.

Fourteen connectors 12a to 12n are provided on the first relay board 102 (an example of the “first board” and another example of the “second board”). The connector 12a (an example of “third connector”) is connected to the second end of the cable 19e (an example of “one end of the second cable”), and the connector 12b is connected to the second end of the cable 19f. Is connected to the second end of the cable 19h, the connector 12d is connected to the second end of the cable 19i, and the connector 12f is connected to the second end of the cable 19j. Are connected, the second end of the cable 19k is connected to the connector 12g, the second end of the cable 19l is connected to the connector 12h, and the second end of the cable 19m is connected to the connector 12i. The connector 12j (an example of “second connector” and another example of “fourth connector”) includes a cable 19n (an example of “first cable” and another example of “second cable”). 1st end (an example of “the other end of the first cable” and (another example of the other end of the second cable)) is connected, and the connector 12k is connected to the first end of the cable 19о. The first end of the cable 19p is connected to the connector 121, the first end of the cable 19q is connected to the connector 12m, and the first end of the cable 19r is connected to the connector 12n.

  The second relay substrate 103 (another example of the “first substrate”) included in the head unit 20 (an example of the “print head unit”) is provided with six connectors 13a to 13f. The connector 13a (an example of the “first connector” and another example of the “third connector”) includes an example of the second end of the cable 19n (an example of the “one end of the first cable”), Another example of “one end”) is connected, the second end of the cable 19о is connected to the connector 13b, the second end of the cable 19p is connected to the connector 13c, and the second end of the cable 19q is connected to the connector 13d. Is connected. Further, the connector 13e (another example of the “second connector”) is connected to the first end (another example of the “other end of the first cable”) of the cable 19s (another example of the “first cable”). The first end of the cable 19t is connected to the connector 13f.

  The head substrate 104 included in the head 21 of the head unit 20 (another example of “printing head unit”) is provided with four connectors 14 a to 14 d. The connector 14a (another example of “first connector”) is connected to the second end of the cable 19s (another example of “one end of the first cable”), and the connector 14b is connected to the second end of the cable 19t. The connector 14c is connected to the second end of the cable 19r, and the connector 14d is connected to the second end of the cable 19d.

  For example, the high power supply voltage signal VHV, the ground voltage signal GND, the drive data COMA_D0, COMA_D1, the drive data COMB_D0, COMB_D1, and the like propagate through the cable 19a. A high power supply voltage signal VHV, a ground voltage signal GND, and the like propagate through the cable 19b. A high power supply voltage signal VHV, a ground voltage signal GND, a temperature signal TH, an abnormal signal XHOT, and the like propagate through the cable 19c. The cable 19d includes a ground voltage signal GND and a plurality of types of control signals (differential signals (SI1 +, SI1-) to (SI6 +, SI6-) of print data signals SI1 to SI6), differential signals (LAT +, LAT of the latch signal LAT). -), Differential signals (CH +, CH-) of the change signal CH, differential signals (SCK +, SCK-)) of the clock signal SCK, etc. are propagated.

The drive signal COMB1, COMA2, COMB3, COMA4, COMB5, COMA6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19e. The drive signals COMA1, COMB2, COMA3, COMB4, COMA5, COMB6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19f. The drive signals COMB1, COMA2, COMB3, COMA4, COMB5, COMA6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19g. The drive signals COMA1, COMB2, COMA3, COMB4, COMA5, COMB6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19h. The drive signals COMB1, COMA2, COMB3, COMA4, COMB5, COMA6, reference voltage signals VBS1 to VBS6, etc. propagate through the cable 19i. Drive signals COMA1, COMB2, COMA3, COMB4, COMA5, COMB6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19j. Drive signals COMB1, COMA2, COMB3, COMA4, COMB5, COMA6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19k. The drive signals COMA1, COMB2, COMA3, COMB4, COMA5, COMB6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19l. The cable 19m propagates a high power supply voltage signal VHV, a low power supply voltage signal VDD, a ground voltage signal GND, a temperature signal TH, an abnormal signal XHOT, and the like.

  The drive signals COMB1, COMA2, COMB3, COMA4, COMB5, COMA6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19n. The drive signals COMA1, COMB2, COMA3, COMB4, COMA5, COMB6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19о. The drive signals COMB1, COMA2, COMB3, COMA4, COMB5, COMA6, reference voltage signals VBS1 to VBS6, etc. propagate through the cable 19p. Drive signals COMA1, COMB2, COMA3, COMB4, COMA5, COMB6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19q. A high power supply voltage signal VHV, a low power supply voltage signal VDD, a ground voltage signal GND, a temperature signal TH, an abnormal signal XHOT, and the like propagate through the cable 19r.

  The drive signals COMB1, COMA2, COMB3, COMA4, COMB5, COMA6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19s. Drive signals COMA1, COMB2, COMA3, COMB4, COMA5, COMB6, reference voltage signals VBS1 to VBS6, and the like propagate through the cable 19t.

  In order to effectively use the space in the casing of the large format printer 1, for example, the control board 100 is fixed to the back side in the casing so that the connection ports of the connectors 10a to 10d face the positive direction of the sub-scanning direction Y. The drive circuit board 101 is fixed to the back side in the housing so that the connection ports of the connectors 11a to 11l face the positive direction of the vertical direction Z, and the first relay board 102 has the connection ports of the connectors 12a to 12n in the vertical direction Z. It is fixed on the back side in the housing so as to face in the positive direction. The second relay board 103 is fixed to the home position side in the carriage 24 so that the connection ports of the connectors 13a to 13f face the negative direction of the main scanning direction X, and the head board 104 has the connection ports of the connectors 14a and 14b. The head 21 is fixed in the head 21 so that it faces the negative direction of the main scanning direction X and the connection ports of the connectors 14c and 14d face the positive direction of the main scanning direction X.

  Based on the arrangement of the control board 100, the drive circuit board 101, the first relay board 102, the second relay board 103, and the head board 104, considering the ease of connection between the boards, the cables 19a to 19t are respectively A type A cable (see FIG. 15) in which connection terminals 193 are provided on the first surface 191 (front surface) at both ends (first end and second end) and one end (first end and second end) In either one), the connection terminal 193 is provided on the first surface 191 (front surface), and the connection terminal 193 is provided on the second surface 192 (back surface) at the other end (one of the first end and the second end). One of the type B cables (see FIG. 16) is used. For example, type A cables (see FIG. 15) are used as the cables 19a to 19d, 19n to 19q, and 19s, and type B cables (see FIG. 16) are used as the cables 19e to 19m, 19r, and 19t.

Here, since the large-format printer 1 can perform serial printing on the print medium P having an A3 short side width or more, the width of the movable region R of the head unit 20 is increased, whereas Thus, the space in which the drive circuit board 101 can be disposed is restricted, and thus the signal lines through which the drive signals COMA and COMB propagate from the drive circuit board 101 to the head unit 20 can be 1 m or more. Therefore, unless any countermeasure is taken, the inductance of the signal line becomes very large, which causes large overshoots and undershoots in the drive signals COMA and COMB, so that the drive signal selection circuit 120 and the piezoelectric element 60 operate. A voltage outside the guaranteed voltage range is instantaneously applied, and the drive signal selection circuit 120 and the piezoelectric element 60 may fail. In addition, the impedance of the signal line is increased, and as a result, the voltage drop of the drive signals COMA and COMB is increased, which may cause a decrease in printing stability.

  Therefore, in the present embodiment, the first relay board 102 and the second relay board 103 are provided for the purpose of reducing the inductance and impedance of the signal lines through which the drive signals COMA (COMA1 to COMA6) and COMB (COMB1 to COMB6) propagate. It has been. Then, the drive signals COMB1, COMA2, COMB3, COMA4, COMB5, and COMA6 propagate from the drive circuit board 101 through the four cables 19e, 19g, 19i, and 19k and are input to the first relay board 102, and the first relay Two cables 19n and 19p are propagated from the board 102 and input to the second relay board 103, and one cable 19s is propagated from the second relay board 103 to the head board 104. Further, the drive signals COMA1, COMB2, COMA3, COMB4, COMA5, and COMB6 propagate from the drive circuit board 101 through the four cables 19f, 19h, 19j, and 19l and are input to the first relay board 102, and the first relay Two cables 19о and 19q are propagated from the board 102 and inputted to the second relay board 103, and one cable 19t is propagated from the second relay board 103 and inputted to the head board 104. That is, the drive signals COMA1 to COMA6 and COMB1 to COMB6 are not propagated through only one cable 19 from the drive circuit board 101 to the head board 104, but are propagated through a plurality of cables 19, thereby The combined inductance and the combined impedance of the signal lines propagating through COMA1 to COMA6 and COMB1 to COMB6 are reduced.

  FIG. 17 shows the relationship between the numbers of the signal lines of the cables 19e to 19l and the signals propagating through the signal lines, the numbers of the connection terminals of the connectors 11d to 11k and 12a to 12h, and the signals input / output from the connection terminals. A specific example is shown. FIG. 18 shows the numbers of the signal lines of the cables 19n to 19q and the signals that propagate through the signal lines, the numbers of the connection terminals of the connectors 12j to 12m and 13a to 13d, and the signals that are input and output from the connection terminals. A specific example of the relationship is shown. FIG. 19 shows the numbers of the signal lines of the cables 19s and 19t, the signals propagated through the signal lines, the numbers of the connection terminals of the connectors 13e, 13f, 14a, and 14b, and the signals input / output from the connection terminals. A specific example of the relationship is shown.

  In the example of FIGS. 17 to 19, for example, the drive signal COMA1 output from the 25th and 23rd terminals of the four connectors 11e, 11g, 11i, and 11k provided on the drive circuit board 101 is the four cables 19f. , 19h, 19j, 19l through the second and fourth signal lines (a total of eight signal lines), and input to the first relay board 102 from the second and fourth terminals of the four connectors 12b, 12d, 12f, and 12h. Is done. In the first relay board 102, the drive signal COMA1 input from the second terminal of the connector 12b and the drive signal COMA1 input from the second terminal of the connector 12d are combined (two drive signals COMA1 having the same drive waveform). The two signal lines that propagate the signal are short-circuited to become one drive signal COMA1), output from the 25th terminal of the connector 12k, input from the 4th terminal of the connector 12b, and the 4th terminal of the connector 12d Are combined with the drive signal COMA1 input from, and output from the 23rd terminal of the connector 12k. Similarly, in the first relay board 102, the drive signal COMA1 input from the second terminal of the connector 12f and the drive signal COMA1 input from the second terminal of the connector 12h are combined and output from the 25th terminal of the connector 12m. Then, the drive signal COMA1 input from the 4th terminal of the connector 12f and the drive signal COMA1 input from the 4th terminal of the connector 12h are combined and output from the 23rd terminal of the connector 12m.

The drive signal COMA1 output from the 25th and 23rd terminals of the connectors 12k and 12m of the first relay board 102 propagates through the 2nd and 4th signal lines (total of 4 signal lines) of the two cables 19о and 19q. The signals are input to the second relay board 103 from the second and fourth terminals of the connectors 13b and 13d. In the second relay board 103, the drive signal COMA1 input from the second terminal of the connector 13b and the drive signal COMA1 input from the second terminal of the connector 13d are combined and output from the 25th terminal of the connector 13f. The drive signal COMA1 input from the 4th terminal of the connector 13b and the drive signal COMA1 input from the 4th terminal of the connector 13d are combined and output from the 23rd terminal of the connector 13f.

  The drive signal COMA1 output from the 25th and 23rd terminals of the connector 13f of the second relay board 103 propagates through the 2nd and 4th signal lines (a total of two signal lines) of one cable 19t, and the connector 14b Input from the 25th and 23rd terminals to the head substrate 104. In the head substrate 104, the drive signals COMA1 input from the 25th and 23rd terminals of the connector 14b are combined and supplied to the drive signal selection circuit 120a.

  The propagation paths of the drive signals COMA2 to COMA6 and COMB1 to COMB6 are also the same as those of the drive signal COMA1, and thus description thereof is omitted.

  Here, unit lengths of all signal lines (total of eight signal lines) through which the drive signal COMA1 propagates in the four cables 19f, 19h, 19j, and 19l connecting the drive circuit board 101 and the first relay board 102. The combined impedance per unit is a unit of all signal lines (total of four signal lines) through which the drive signal COMA1 propagates in the two cables 19о and 19q connecting the first relay board 102 and the second relay board 103. Less than the combined impedance per length. In addition, the synthesis per unit length of all signal lines (total of four signal lines) through which the drive signal COMA1 propagates in the two cables 19о and 19q connecting the first relay board 102 and the second relay board 103. The impedance is higher than the combined impedance per unit length of all signal lines (two signal lines in total) through which the drive signal COMA1 propagates in one cable 19t connecting the second relay board 103 and the head board 104. small. The same applies to the drive signals COMA2 to COMA6 and COMB1 to COMB6. Therefore, according to the large-format printer 1 according to the present embodiment, serial printing can be performed on the printing medium P having an A3 short side width or more, and thus the drive signal COMA (COMA1) is transmitted to the head unit 20 (head 21). ~ COMA6) and COMB (COMB1 to COMB6) propagate in the signal line, but the combined impedance and the first relay of all signal lines through which the drive signals COMA and COMB propagate from the drive circuit board 101 to the first relay board 102 Since the combined impedance of all signal lines through which the drive signals COMA and COMB propagate from the substrate 102 to the second relay substrate 103 is reduced, the voltage drop of the drive signals COMA and COMB is reduced, and high printing accuracy and printing stability are achieved. Can be realized.

Further, the unit length of all signal lines (a total of eight signal lines) through which the drive signal COMA1 propagates in the four cables 19f, 19h, 19j, and 19l connecting the drive circuit board 101 and the first relay board 102. The combined inductance per unit is the unit length of all signal lines (a total of four signal lines) through which the drive signal COMA1 propagates in the two cables 19о and 19q connecting the first relay board 102 and the second relay board 103. It is smaller than the combined inductance per unit. In addition, the synthesis per unit length of all signal lines (total of four signal lines) through which the drive signal COMA1 propagates in the two cables 19о and 19q connecting the first relay board 102 and the second relay board 103. The inductance is greater than the combined inductance per unit length of all signal lines (two signal lines in total) through which the drive signal COMA1 propagates in one cable 19t connecting the second relay board 103 and the head board 104. small. The same applies to the drive signals COMA2 to COMA6 and COMB1 to COMB6. Therefore, according to the large-format printer 1 according to the present embodiment, serial printing can be performed on the printing medium P having an A3 short side width or more, and thus the drive signal COMA (COMA1) is transmitted to the head unit 20 (head 21). ~ COMA6) and COMB (COMB1 to COMB6) propagate in the signal line, but the combined inductance and the first relay of all signal lines through which the drive signals COMA and COMB propagate from the drive circuit board 101 to the first relay board 102 Since the combined inductance of all signal lines through which the drive signals COMA and COMB propagate from the substrate 102 to the second relay substrate 103 is reduced, overshoot and undershoot of the drive signals COMA and COMB are reduced, and the head unit 20 (head 21) is less likely to cause a failure or malfunction.

  As described above, the control board 100, the drive circuit board 101, and the first relay board 102 are fixed in the casing of the large format printer 1, and thus do not move with the movement of the head unit 20. Accordingly, the cables 19a to 19c and 19e to 19m that connect any two of the control board 100, the drive circuit board 101, and the first relay board 102 are not deformed with the movement of the head unit 20 for serial printing. Further, the second relay board 103 and the head board 104 provided in the head unit 20 move as the head unit 20 moves for serial printing, but the relative positional relationship between these boards does not change. Accordingly, the cables 19a and 19b connecting the second relay substrate 103 and the head substrate 104 are not deformed with the movement of the head unit 20 for serial printing. Accordingly, the cable 19d for connecting the control board 100 and the head board 104, the cable 19r for connecting the first relay board 102 and the head board 104, and the cables 19n for connecting the first relay board 102 and the second relay board 103 are connected. Only 19q is deformed with the movement of the head unit 20 for serial printing. Thus, according to the large-format printer 1 according to the present embodiment, the number of cables that are connected to the head unit 20 and deform as the head unit 20 moves is not connected to the head unit 20, and the head unit 20 moves. Accordingly, there is a risk that problems such as failure or malfunction of the head unit 20 (head 21), deterioration of printing accuracy and printing stability, etc. may occur while securing the movability of the head unit 20 because the number of cables is not deformed. Can be reduced.

  In the present embodiment, the first relay board 102 and the second relay board 103 are connected by four cables 19n to 19q, but the first relay board 102 and the second relay board 103 are connected. The greater the number of cables 19 that are connected, the smaller the combined inductance and combined impedance of the signal lines through which the drive signals COMA and COMB propagate, and the printing accuracy and stability are improved. Further, the resonance frequency determined by the inductor L1 and the capacitor C1 (see FIG. 12) of the drive circuits 50a to 50d, the combined inductance of the signal lines through which the drive signals COMA and COMB propagate, and the combined capacitance of the piezoelectric element 60 are determined. , The waveforms of the drive signals COMA and COMB are distorted. In general, the smaller the combined inductance of the signal lines through which the drive signals COMA and COMB propagate, the greater the difference between the two resonance frequencies. The possibility that the printing accuracy and stability are lowered is reduced. On the other hand, when the number of cables 19 that connect the first relay board 102 and the second relay board 103 increases, the cost increases and the slidability of the head unit 20 deteriorates. Therefore, it is preferable to set the number of cables to an appropriate value in consideration of the tradeoff between the advantages and disadvantages of increasing the number of cables.

In the present embodiment, the control signals (differential signals (SI1 +, SI1-) to (SI6 +, SI6 +, SI6 +) of the print data signals SI1 to SI6) for controlling the discharge of the liquid (ink) from the head unit 20 (head 21). ), The differential signal (LAT +, LAT−) of the latch signal LAT, the differential signal (CH +, CH−) of the change signal CH, and the differential signal (SCK +, SCK−) of the clock signal SCK) from the control board 100. The cable 19d is propagated to the head substrate 104. That is, these control signals propagate to the head substrate 104 (head 21) without passing through the drive circuit substrate 101, the first relay substrate 102, and the second relay substrate 103. Therefore, according to the large-format printer 1 according to the present embodiment, crosstalk between the drive signals COMA and COMB and these control signals in the drive circuit board 101, the first relay board 102, and the second relay board 103 is avoided. This reduces the influence of the low voltage control signal from the high voltage drive signals COMA and COMB, reduces the possibility of the head unit 20 (head 21) malfunctioning, and realizes high printing accuracy and printing stability. it can.

  Further, in the present embodiment, a large number of cables 19 are used, and in particular, since many cables 19 are connected to the drive circuit board 101, the first relay board 102, and the second relay board 103, each cable 19 is as much as possible. The layout of each connector is taken into consideration so as to shorten the length. FIG. 20 is a diagram showing the arrangement of connectors on the drive circuit board 101. FIG. 21 is a diagram showing the arrangement of connectors on the first relay board 102. FIG. 22 is a diagram showing the arrangement of the connectors on the second relay board 103. FIG. 23 schematically shows the arrangement of the drive circuit board 101, the first relay board 102, the second relay board 103, and the cables 19d to 19r when the large format printer 1 is viewed in the negative direction of the sub-scanning direction Y. FIG.

  As shown in FIGS. 20 and 23, the surface (connecting surface) on which the connectors 11 a to 11 l of the drive circuit board 101 are provided faces the positive direction of the vertical direction Z. That is, the drive circuit board 101 is fixed in the casing of the large format printer 1 so that the connection surface faces upward. The three connectors 11a to 11c are arranged in this order toward the negative direction of the sub-scanning direction Y on the side close to the home position, and the nine connectors toward the positive direction of the sub-scanning direction Y on the side far from the home position. 11d to 11l are arranged in this order. That is, the three connectors 11a to 11c connected to the control board 100 by the cables 19a to 19c are provided on the side close to the control board 100, and the nine connectors connected to the first relay board 102 by the cables 19e to 19m. 11 d to 11 l are provided on the side close to the first relay substrate 102. As a result, the cables 19a to 19c and 19e to 19m are shortened.

  As shown in FIGS. 21 and 23, the surface (connecting surface) on which the connectors 12 a to 12 j of the first relay board 102 are provided faces the positive direction of the vertical direction Z. That is, the first relay board 102 is fixed in the casing of the large format printer 1 so that the connection surface faces upward. Then, nine connectors 12a to 12i are arranged in this order on the side close to the home position in the positive direction of the main scanning direction X, and five connectors are arranged on the side far from the home position in the negative direction of the main scanning direction X. 12j to 12n are arranged in this order. That is, nine connectors 12a to 12i connected to the drive circuit board 101 by the cables 19e to 19m are provided on the side close to the drive circuit board 101, and four connectors to be connected to the second relay board 103 by the cables 19n to 19q. The connectors 12j to 12m and the connector 12n connected to the head substrate 104 by the cable 19r are provided on the side close to the head unit 20 (the second relay substrate 103 and the head substrate 104). As a result, the cables 19e to 19q are shortened.

  As shown in FIGS. 22 and 23, the surface (connection surface) on which the connectors 13a to 13f of the second relay substrate 103 are provided faces the negative direction of the main scanning direction X. That is, the second relay substrate 103 is fixed in the carriage 24 of the head unit 20 so that the connection surface faces the home position side. Then, four connectors 13a to 13d are arranged in this order toward the positive direction of the sub-scanning direction Y on the side close to the back surface of the housing, and 2 toward the negative direction of the vertical direction Z on the side close to the front surface of the housing. The connectors 13e and 13f are arranged in this order. That is, the four connectors 13a to 13d connected to the first relay board 102 by the cables 19n to 19q are connected to the head board 104 by the cables 19s and 19t, with the connection ports facing the first relay board 102. The individual connectors 13e and 13f face the same direction as the two connectors 14a and 14b provided on the head substrate 104. Accordingly, the cables 19n to 19q, 19s, and 19t are shortened.

As shown in FIG. 23, the cables 19e to 19m for connecting the drive circuit board 101 and the first relay board 102 and the cable 19d for connecting the control board 100 and the head board 104 (not shown in FIG. 23) are vertical. They overlap in this order toward the positive direction of direction Z. On the other hand, as shown in FIG. 20, in the drive circuit board 101, the nine connectors 11d to 11l are all in the same direction (terminal surface) where the connection terminals are provided inside the connection ports (terminal surfaces). The nine connectors 12a to 12i are all in the same direction (in the main scanning direction X) in the first relay board 102, as shown in FIG. (Negative direction) The cables 19e to 19m are bent and connected to the connectors 11d to 11l and the connectors 12a to 12i, respectively. Thereby, the arrangement space of the cables 19e to 19m is reduced.

  23, cables 19n to 19q that connect the first relay board 102 and the second relay board 103, cables 19r that connect the first relay board 102 and the head board 104, and the control board 100, The cable 19d connecting the head substrate 104 overlaps in this order toward the positive direction of the vertical direction Z. On the other hand, as shown in FIG. 21, in the first relay board 102, the terminal surfaces of the five connectors 12j to 12n all face the same direction (the positive direction of the main scanning direction X). As shown in FIG. 22, on the connection surface of the second relay substrate 103, the terminal surfaces of the four connectors 13 a to 13 d all face the same direction (the negative direction of the sub-scanning direction Y). The cables 19n to 19r are bent and connected to the connectors 12j to 12n and the connectors 13a to 13d and 14c (not shown in FIG. 23), respectively. Thereby, the arrangement space of the cables 19n to 19r is reduced.

  In particular, in this embodiment, as shown in FIG. 23, the cables 19n to 19r and 19d are overlapped to form an arc AR, and the four cables 19n to 19q through which the drive signals COMA and COMB propagate are transmitted to the control signal (difference). The moving signals (SI1 +, SI1-) to (SI6 +, SI6-), (LAT +, LAT−), (CH +, CH−), (SCK +, SCK−)) are outside the arc AR than the cable 19d that propagates. . Even if the head unit 20 moves, the overlapping order of the cables 19n to 19r and 19d in the arc AR does not change.

  As described above, the drive signals COMA and COMB are propagated from the drive circuit board 101 through the first relay board 102 through the cables 19n to 19q and supplied to the head unit 20 (second relay board 103). Thus, the control signal propagates through the cable 19d without passing through the first relay substrate 102 and propagates to the head unit 20 (head substrate 104). The cables 19n to 19q connected to the first relay board 102 are connected to the head unit 20 through the outside of the arc AR, and the cable 19d not connected to the first relay board 102 is passed through the inside of the arc AR. 20, the overlapping order of the cables 19 n to 19 q and 19 d does not change in the middle between the first relay board 102 and the head unit 20, so that the crosstalk between the drive signals COMA and COMB and the control signal is reduced. Get smaller. Therefore, according to the large-format printer 1 according to the present embodiment, serial printing can be performed on the printing medium P having an A3 short side width or more, and thus the drive signals COMA, COMB and the control signal are transmitted to the head unit 20. Although the propagating signal line becomes long, the influence of the low-voltage control signal from the high-voltage drive signals COMA and COMB is reduced, so that the possibility of malfunction of the head unit 20 (head 21) is reduced and high printing is performed. Accuracy and printing stability can be realized.

  Further, since the cable 19d through which the low-voltage control signal propagates passes through the inside of the arc AR and is connected to the head unit 20, friction between the housing and the cable 19d due to the movement of the head unit 20 hardly occurs, and the cable 19d Is less likely to be charged, so that the circuit (selection control unit 220 or the like) that operates at a low power supply voltage mounted on the head unit 20 is less likely to cause electrostatic breakdown and the head unit 20 (head 21) to fail.

In addition, since the overlapping order of the cables 19n to 19q and 19d does not change in the middle, the cables 19n to 19q through which the drive signals COMA and COMB propagate are avoided from being unnecessarily long, and the drive signals COMA and COMB to the head unit 20 are avoided. The inductance and impedance of the signal line that propagates is reduced. Therefore, according to the large-format printer 1 according to the present embodiment, the overshoot and undershoot of the drive signals COMA and COMB and the voltage drop of the drive signals COMA and COMB are reduced, so that the head unit 20 (head 21) is broken down. The possibility of malfunctioning is reduced, and high printing accuracy and printing stability can be realized.

  Since the control signal propagating through the cable 19d is a differential signal, the influence of the common mode noise is reduced, but the influence of the noise that the low voltage control signal receives from the high voltage drive signals COMA and COMB is reduced. Therefore, the cable 19d through which the control signal propagates is preferably a cable (shielded cable) having a shield part that protects the control signal. FIG. 24 shows an example of a shielded cable. The shielded cable shown in FIG. 24 is covered with a shield tape 194 (shield portion) including a conductive shield wire inside, and is electrically connected so as to have a fixed potential (for example, ground potential) at the shield wire exposed portion 195. This structure is noise-resistant. The shield wire does not necessarily have to be linear (that is, the wiring does not have to be lined up), the conductive thin wires may be knitted, or the metal layer inside the shield tape 194 It may be a shielded wire.

  Further, as shown in FIG. 23, the cables 19n to 19r, 19d are connected to the drive signal COMA through which the high power supply voltage signal VHV, which is a constant voltage signal, the low power supply voltage signal VDD, the ground voltage signal GND, and the like propagate. , COMB propagates so as to be sandwiched between a group of cables 19n to 19q propagating through COMB and a cable 19d through which a control signal propagates, forming an arc AR. The impedance per unit length of the signal line through which the constant voltage signal propagates in the cable 19r is smaller than the impedance per unit length of the signal line through which the drive signals COMA and COMB propagate in the cables 19n to 19q, and It is smaller than the impedance per unit length of the signal line through which the control signal propagates in the cable 19d. Specifically, the thickness (for example, 100 μm) of the signal line through which the constant voltage signal propagates in the cable 19r is larger than the thickness (eg, 50 μm) of the signal line through which the drive signals COMA and COMB propagate in the cables 19n to 19q. In addition, the thickness of the signal line through which the control signal propagates in the cable 19d (for example, 50 μm) is larger.

  As described above, since the cable 19r having a small impedance and the constant voltage signal propagated is sandwiched between the group of cables 19n to 19q and the cable 19d in which the control signal propagates, the cable 19r functions as a shield wire. Crosstalk between the drive signals COMA and COMB propagating through 19n to 19q and the control signal propagating through the cable 19d is reduced. Therefore, according to the large-format printer 1 according to the present embodiment, serial printing can be performed on the printing medium P having an A3 short side width or more, so that the cables 19n to 19q and 19d become long, but the low voltage Therefore, the influence of the control signal from the high-voltage drive signals COMA and COMB is reduced, so that the possibility of malfunction of the head unit 20 is reduced, and high printing accuracy and printing stability can be realized.

Further, as shown in FIG. 23, the number (four) of the cables 19 outside the arc AR from the cable 19r is larger than the number (one) of the cables 19 inside the arc AR from the cable 19r. Many. That is, between the arc AR and the head unit 20, many cables 19n to 19q overlap the cable 19r, so that these cables 19n to 19q are likely to hang down due to their own weight. On the other hand, since the cable 19r has a signal line thicker than the cables 19n to 19q and 19d, the cable 19r has high strength and also functions as a core material for preventing the cables 19n to 19q from drooping. Therefore, during the movement of the head unit 20, the dynamic change in the mutual inductance of the cables 19n to 19q and 19d due to the cables 19n to 19q hanging down and deforming due to their own weight is reduced. Therefore, according to the large-format printer 1 according to the present embodiment, serial printing can be performed on the printing medium P having an A3 short side width or more, and thus the cables 19n to 19q and 19d become long. Since the reproducibility of the COMA and COMB waveforms is improved, high printing accuracy and printing stability can be realized.

  Further, since the signal line of the cable 19r is thick and has a small impedance, the voltage drop of the constant voltage signal (high power supply voltage signal VHV, low power supply voltage signal VDD, ground voltage signal GND, etc.) that propagates is small, and the drive signal The possibility that the selection circuits 120a to 120f malfunction will be reduced. In this embodiment, in order to further reduce the voltage drop of the constant voltage signal, the signal lines of the cables 19c and 19m through which the constant voltage signal propagates also have the same thickness (for example, 100 μm) as the signal line of the cable 19r. It has become.

  In addition, since the cables 19c, 19m, and 19r through which the constant voltage signal propagates have a high shielding effect, the large-format printer 1 according to the present embodiment is extremely important in order to prevent the head unit 20 from malfunctioning, and the temperature signal TH and abnormalities. The signal XHOT is configured to propagate through the cables 19c, 19m, and 19r.

  FIG. 25 shows the numbers of the signal lines of the cables 19c, 19m, and 19r, the signals that propagate through the signal lines, the numbers of the connection terminals of the connectors 10c, 11c, 11l, 12i, 12n, and 14c, and the input / output from the connection terminals. A specific example of the relationship with the signal to be transmitted will be shown.

  In the example of FIG. 25, the temperature signal TH output from the 24th terminal of the connector 14c provided on the head substrate 104 propagates through the 3rd signal line of the cable 19r, and the first relay substrate from the 24th terminal of the connector 12n. 102 and output from the third terminal of the connector 12i. The temperature signal TH output from the third terminal of the connector 12i propagates through the third signal line of the cable 19m, is input from the third terminal of the connector 11l to the drive circuit board 101, and is output from the third terminal of the connector 11c. The The temperature signal TH output from the third terminal of the connector 11c propagates through the third signal line of the cable 19c and is input to the control board 100 from the 24th terminal of the connector 10c. In the cables 19c, 19m, and 19r, the second and fourth signal lines through which the low power supply voltage signal VDD, which is a constant voltage signal, are provided on both sides of the third signal line through which the temperature signal TH propagates. Therefore, the second and fourth signal lines of the cables 19c, 19m, and 19r function as shield lines, and since they are analog signals, the temperature signal TH that is easily affected by the high-voltage drive signals COMA and COMB is output from the head substrate 104. Propagates stably to the control board 100. Therefore, according to the large-format printer 1 according to the present embodiment, the possibility that the control based on the temperature signal TH of the control unit 111 (such as correction of the temperature dependency of the ink ejection characteristics by the head unit 20) is reduced is reduced, and the printing accuracy is reduced. And the printing stability can be improved.

In the example of FIG. 25, the abnormal signal XHOT output from the 4th terminal of the connector 14c provided on the head substrate 104 propagates through the 23rd signal line of the cable 19r and the first signal from the 4th terminal of the connector 12n. The signal is input to the relay board 102 and output from the 23rd terminal of the connector 12i. The abnormal signal XHOT output from the 23rd terminal of the connector 12i propagates through the 23rd signal line of the cable 19m, is input to the drive circuit board 101 from the 23rd terminal of the connector 11l, and is output from the 23rd terminal of the connector 11c. The The abnormal signal XHOT output from the 23rd terminal of the connector 11c propagates through the 23rd signal line of the cable 19c and is input to the control board 100 from the 4th terminal of the connector 10c. In the cables 19c, 19m, and 19r, the 22nd and 24th signal lines on which the ground voltage signal GND that is a constant voltage signal propagates are provided on both sides of the 23rd signal line on which the abnormal signal XHOT propagates. Therefore, the 22nd and 24th signal lines of the cables 19c, 19m, and 19r function as shield lines, and the abnormal signal XHOT is stably propagated from the head substrate 104 to the control substrate 100. Therefore, according to the large-format printer 1 according to the present embodiment, the possibility of erroneous control (such as a stop instruction for the head unit 20) based on the abnormal signal XHOT of the control unit 111 is reduced.

  The first relay board 102 moves when the head unit 20 is viewed from a direction (for example, the sub-scanning direction Y) orthogonal to the direction (main scanning direction X) in which the head unit 20 moves for serial printing. It is preferable that the region (movable region R) is provided so as to at least partially overlap, and it is more preferable that the region (movable region R) is provided near the center of the movable region R. In this way, the cables 19n to 19r can be made shorter, so that charging due to friction with the housing is reduced, and the dynamic change in mutual inductance is reduced, so that the head unit 20 (head 21) is less likely to break down, and printing accuracy and printing stability are improved.

  As described above, in the large format printer 1 according to the present embodiment, a large number of cables 19 are used, and the number of connection terminals 193 provided at the first end or the second end of all the cables 19 is large. Since they are the same, errors in the connection locations and connection directions of the cables 19 are likely to occur. Therefore, in order to make it difficult to make an error in the connection direction of the cable 19, as described above, the connection terminals 193 are provided only on one side (the first surface 191 or the second surface 192) at both ends of all the cables 19a to 19r. (See FIGS. 15 and 16). In all the connectors 10a to 10d, 11a to 11l, 12a to 12n, 13a to 13f, and 14a to 14d, connection terminals are provided only on one surface (terminal surface) inside the connection port. As a result, if the connection direction of each cable 19 to each connector is wrong, the connection terminals are not correctly connected physically or electrically.

  Furthermore, since a number of cables 19 are connected to the drive circuit board 101 and the first relay board 102, errors in connection locations of the cables 19 are particularly likely to occur. Therefore, as shown in FIG. 21, in the first relay board 102, the terminal surfaces of the connectors 12j to 12n and the terminal surfaces of the connectors 12a to 12i face different directions. Specifically, the terminal surfaces of the connectors 12j to 12n and the terminal surfaces of the connectors 12a to 12i face in opposite directions (the former is directed in the positive direction of the main scanning direction X, and the latter is negative in the main scanning direction X). Facing the direction). Therefore, at least one of the cables 19e to 19m to be connected to the connectors 12a to 12i is erroneously connected to any of the connectors 12j to 12n, or the cables 19n to 19r to be connected to the connectors 12j to 12n, respectively. Even if at least one of the connectors is mistakenly connected to any of the connectors 12a to 12i, the connection terminals are not physically or electrically connected correctly, and the cables 19e to 19m and the cables 19n to 19r are inserted incorrectly. Hard to happen.

  Similarly, as shown in FIG. 22, in the second relay substrate 103, the terminal surfaces of the connectors 13e and 13f and the terminal surfaces of the connectors 13a to 13d face different directions. Specifically, the terminal surfaces of the connectors 13e and 13f and the terminal surfaces of the connectors 13a to 13d are oriented in a direction orthogonal (the former is directed in the negative direction of the vertical direction Z, and the latter is negative in the sub-scanning direction Y). Facing the direction). Therefore, at least one of the cables 19n to 19q to be connected to the connectors 13a to 13d is connected to one of the connectors 13e and 13f, or at least one of the cables 19s and 19t to be connected to the connectors 13e and 13f, respectively. Since it is difficult to connect one to any of the connectors 13a to 13d, it is difficult for the cables 19n to 19q and the cables 19s and 19t to be inserted incorrectly.

Therefore, according to the large-format printer 1 according to the present embodiment, the possibility that the head unit 20 (head 21) breaks down or malfunctions due to a wrong insertion of the cable in the first board is reduced.

  However, there is a possibility that the connection terminals may cause a contact failure such as a short circuit when each cable 19 is inserted into each connector obliquely. In such a contact failure state, the drive signals COMA, COMB, various control signals and the like cannot be properly propagated to the head substrate 104, and malfunction such as discharge failure may occur. The signal selection circuits 120a to 120f and the piezoelectric element 60 may fail. Therefore, in the large-format printer 1 according to the present embodiment, the cables 19a to 19r constitute at least a part of the daisy chain, and the daisy chain can detect a connection failure between each cable and each connector.

  FIG. 26 is a diagram illustrating an example of a daisy chain. In the example shown in FIG. 26, as indicated by arrows, the signal lines at both ends of all cables 19 (No. 1, 26 signal lines) and the connection terminals at both ends of all connectors (No. 1, 26 connection terminals) are provided. A connected daisy chain is configured. Then, the control unit 111 provided on the control board 100 supplies the connection confirmation signal FCC to the first terminal of the connector 10c. If all the cables 19 and all the connectors are properly connected, the connection confirmation signal FCC propagates through the daisy chain to the end, and the connection confirmation signal FCC is input to the control unit 111 from the 26th terminal of the connector 10a. . On the other hand, if the connection of at least one cable 19 or at least one connector is inappropriate, the connection confirmation signal FCC cannot propagate through the daisy chain to the end, and the control unit 111 receives the connector 10a. A signal different from the connection confirmation signal FCC is input from the 26th terminal. Therefore, the control unit 111 can confirm the connection based on whether or not the signal input from the 26th terminal of the connector 10a matches the connection confirmation signal FCC. If it is determined that the connection is defective, the control unit 111 may stop the generation of the drive signals COMA and COMB by the drive circuits 50a to 50d. Therefore, according to the large-format printer 1 according to the present embodiment, there is a possibility that a short circuit occurs between the connection terminals of the connectors due to at least one oblique stab of the cables 19a to 19r and the head unit 20 (head 21) breaks down or malfunctions. Get smaller.

  The control unit 111 uses a constant voltage signal such as the ground voltage signal GND as the connection confirmation signal FCC, so that the connection confirmation signal FCC does not become a noise source. can do. Moreover, the signal line through which the connection confirmation signal FCC, which is a constant voltage signal, propagates functions as a shield line. Therefore, for example, in the example of FIG. 25, the temperature signal TH propagates through the second signal line of the cables 19c, 19m, 19r, the 25th terminal of the connectors 10c, 12n, 14c and the second terminal of the connectors 11c, 11l, 12i. In addition, the low power supply voltage signal VDD is changed so as to propagate through the third signal line of the cables 19c, 19m, 19r, the 24th terminal of the connectors 10c, 12n, 14c and the third terminal of the connectors 11c, 11l, 12i. As a result, the first signal line through which the connection confirmation signal FCC propagates in the cables 19c, 19m, and 19r can be used as a shield line for protecting the temperature signal TH.

8). As described above, according to the large-format printer 1 according to the present embodiment, since it is possible to perform serial printing on the print medium P having an A3 short side width or more, various signals propagate. Although the signal line becomes long, the possibility of failure or malfunction of the head unit 20 (head 21) is reduced, and high printing accuracy and printing stability can be realized.

In particular, when the maximum printing width (platen width PW) of serial printing is 24 inches or more, the total length of the signal line through which the drive signals COMA and COMB propagate can be 1 m or more, so that the impedance and inductance of the signal line are reduced. Alternatively, the above-described various effects by reducing the crosstalk between the drive signals COMA and COMB and the control signal are greater. However, if the maximum width capable of serial printing exceeds 75 inches, the total length of the signal lines through which the drive signals COMA and COMB propagate can be 3 m or more. For this reason, the impedance or inductance of the signal line through which the drive signal propagates becomes too large, or the crosstalk between the drive signals COMA and COMB and the control signal becomes too large, causing the head unit 20 (head 21) to malfunction or malfunction. The above effects are difficult to obtain. Therefore, the large-format printer 1 according to the present embodiment preferably has a maximum serial printing width (platen width PW) of 24 inches or more and 75 inches or less.

  The large-format printer 1 according to the present embodiment may correspond to a maximum printing width (platen width PW) of serial printing of 24 inches, 36 inches, 44 inches, or 64 inches. According to the large-format printer 1, excellent printing accuracy and printing stability can be realized as a 24-inch printer, a 36-inch printer, a 44-inch printer, or a 64-inch printer that is particularly in great demand.

  In the large format printer 1 according to the present embodiment, the head unit 20 (head 21) may eject liquid (ink) at a frequency of 30 kHz or more. The higher the frequency of ejecting ink (the higher the printing speed), the steeper voltage change of the drive signals COMA and COMB increases the overshoot and undershoot. Also, the drive signals COMA and COMB and the control signal The crosstalk is also likely to increase. Therefore, according to the large format printer 1, the various effects described above are greater.

  Furthermore, according to the large-format printer 1 according to the present embodiment, since the weight of the head unit 20 is smaller than that in the case where the drive circuit 50 is mounted on the carriage 24, the motor for reciprocating the head unit 20 is used. An expensive motor is not required, vibration during reciprocation of the head unit 20 is small, and the head 21 is not affected by the heat generated by the drive circuit 50, so that printing accuracy and printing stability are high.

9. In the above embodiment, there are two substrates (relay substrates) for relaying the drive signals COMA and COMB to the head substrate 104 (first relay substrate 102 and second relay substrate 103). There may be one, or three or more. Moreover, the number of the cables 19 that connect the substrates is not limited to that exemplified in the above embodiment.

  In the above embodiment, a piezoelectric large format printer in which a drive circuit drives a piezoelectric element (capacitive load) as a drive element is taken as an example. However, the present invention is a drive in which the drive circuit is a drive other than a capacitive load. It can also be applied to large format printers that drive the elements. As such a large format printer, for example, a driving circuit drives a heating element (for example, a resistor) as a driving element, and discharges liquid (ink) using bubbles generated by heating the heating element. Thermal type (bubble type) large format printers are listed.

  As mentioned above, although this embodiment or the modification was demonstrated, this invention is not limited to these this embodiment or a modification, It is possible to implement in a various aspect in the range which does not deviate from the summary. For example, it is possible to appropriately combine the above-described embodiment and each modification.

The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objects and effects). In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that exhibits the same operational effects as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Large format printer, 2 ... Main body, 3 ... Support stand, 4 ... Supply part, 6 ... Discharge part, 7 ... Operation part, 8 ... Ink storage part, 9 ... Ink tube, 10a-10d, 11a-11l, 12a- 12n, 13a to 13f, 14a to 14d ... connector, 19, 19a to 19t ... cable, 20 ... head unit, 21 ... head, 24 ... carriage, 32 ... carriage guide shaft, 33 ... platen, 35 ... capping mechanism, 50, 50 ... 50d ... Drive circuit, 60 ... Piezoelectric element, 80 ... Maintenance mechanism, 100 ... Control board, 101 ... Drive circuit board, 102 ... First relay board, 103 ... Second relay board, 104 ... Head board, 111 ... Control 112, power supply circuit, 113 control signal transmission unit, 114 voltage conversion circuit, 115 control signal reception unit, 116 temperature detection circuit 120, 120a to 120f: drive signal selection circuit, 191: first surface, 192: second surface, 193 ... connection terminal, 194 ... shield tape, 195 ... shield wire exposed portion, 220 ... selection control portion, 222 ... shift register DESCRIPTION OF SYMBOLS 224 ... Latch circuit, 226 ... Decoder, 230 ... Selection part, 232a, 232b ... Inverter, 234a, 234b ... Transfer gate, 500 ... Integrated circuit device, 501 ... Integration part, 510 ... Modulation part, 511 ... DAC, 512 513 ... Adder, 514 ... Comparator, 515 ... Inverter, 516 ... Integral attenuator, 517 ... Attenuator, 520 ... Gate driver, 521 ... First gate driver, 522 ... Second gate driver, 530 ... First power supply unit 550: Output circuit, 560: Low pass filter, 570: First Return circuit, 572, second feedback circuit, 580, reference voltage generation unit, 600, discharge unit, 601, piezoelectric body, 611, 612, electrode, 621, diaphragm, 631, cavity, 632, nozzle plate, 641 ... Reservoir, 650 ... Nozzle row, 650a to 650l ... First nozzle row to twelfth nozzle row, 651 ... Nozzle, 661 ... Supply port, C1, C2, C3, C4, C5 ... Condenser, D1 ... Diode, R1, R2, R3, R4, R5, R6 ... resistor, L1 ... inductor, M1 ... first transistor, M2 ... second transistor

Claims (6)

A large-sized printer capable of serial printing on a medium having an A3 short side width or larger,
A print head having a first connector and discharging liquid;
A first substrate having a second connector and a third connector;
A second substrate having a fourth connector;
A first cable connected at one end to the first connector and connected at the other end to the second connector;
A second cable connected at one end to the third connector and connected at the other end to the fourth connector;
The other end of the first cable is provided with a terminal only on one side of the first cable,
The one end of the second cable is provided with a terminal only on one side of the second cable,
The number of terminals provided at the other end of the first cable and the number of terminals provided at the one end of the second cable are the same;
The terminal surface on which the terminal is provided in the second connector and the terminal surface on which the terminal is provided in the third connector are facing different directions.
A large format printer. The terminal surface of the second connector and the terminal surface of the third connector are in a direction orthogonal to each other,
The large format printer according to claim 1, wherein: The terminal surface of the second connector and the terminal surface of the third connector are facing in opposite directions;
The large format printer according to claim 1, wherein the large format printer is provided. The maximum width capable of serial printing is not less than 24 inches and not more than 75 inches,
The large format printer according to claim 1, wherein the large format printer is provided. The maximum width capable of serial printing corresponds to any of 24 inches, 36 inches, 44 inches, and 64 inches.
The large format printer according to claim 4, wherein: The print head unit ejects the liquid at a frequency of 30 kHz or more;
The large format printer according to claim 1, wherein the large format printer is provided.