JP2009241379A - Liquid droplet discharge system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid droplet discharge system capable of executing a high-speed printing while moving a printing medium by a simple system by eliminating a time lag in ink discharge between heads at printing. <P>SOLUTION: The communication of a picture signal is established by daisy chain connection, and the communication of a discharge timing signal is established by a connection method different from the daisy chain connection to eliminate a time lag in ink discharge between the heads. Thus, the liquid droplet discharge system can execute high speed printing while moving the printing medium by the simple system. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a droplet discharge system, and more particularly to a droplet discharge system that transmits an image signal, a control signal, and a discharge timing signal by different connection methods.

  Conventionally, in a droplet discharge system such as an ink jet method, when a plurality of head drive units are connected to one control unit to form a droplet discharge system having a large number of ink discharge nozzles, the number of wirings is reduced. In order to achieve this, it has been generally performed to communicate through a daisy chain connection.

  However, in the daisy chain connection, various signals such as print data and timing signals for printing are sequentially transmitted via a plurality of head drive units. Therefore, the head in the subsequent stage of the daisy chain connection depends on the propagation characteristics of the transmission path. As the driving unit is used, various signal delays occur, and the printing timing is shifted, which adversely affects the printing result.

  This will be described with reference to FIGS. FIG. 7 is a block diagram showing a configuration of a conventional droplet discharge system.

  In FIG. 7, the droplet discharge system 1 includes an operation unit 2, a printing device 3, and the like.

  The operation unit 2 generates an image to be printed and transmits the image as an image signal 11 to the printing apparatus 3.

  The printing apparatus 3 includes a transport unit 4, a control unit 5, a printing unit 6, and the like. The transport unit 4 transports the print medium 9 such as print paper and generates a movement amount signal 15 indicating the movement amount of the print medium 9 and transmits it to the control unit 5.

  The control unit 5 generates an ejection timing signal 17 for ejecting ink at a predetermined timing based on the movement amount signal 15 received from the transport unit 4, and transmits the ejection timing signal 17 to the printing unit 6. The control unit 5 stores the image signal 11 received from the operation unit 2 and transmits it to the printing unit 6 at a predetermined timing.

  The printing unit 6 includes a plurality of (here, n: n is a positive integer) head driving units 7 and a plurality (here, n: n is a positive integer) heads 8 and the like.

  The head drive unit 7 stores data (print data) 19 of a portion to be printed by the head controlled by the head, among the image signals 11 received from the control unit 5, and matches the ejection timing signal 17 received from the control unit 5. Then, the head 8 is driven based on the stored print data 19.

  The head 8 has a plurality of (here, n: n is a positive integer) heads 8 each having a plurality of (here, m: m is a positive integer) nozzles, and is driven by the head drive unit 7. Ink is ejected in accordance with the ejection timing signal 17 and printing is performed on the print medium 9 with the ejected ink dots.

  The flow of various signals in the printing apparatus 3 is as follows. Based on the movement amount signal 15 transmitted from the transport unit 4 to the control unit 5, the image signal 11 and the ejection timing signal 17 are sent from the control unit 5 to the first head drive unit 71 of the n head drive units 7. Sent to.

  The head drive unit 71 drives the head 81 driven by itself among the n heads 8 based on the received image signal 11 and ejection timing signal 17. At the same time, the received image signal 11 and ejection timing signal 17 are transmitted to the adjacent head drive unit 72 connected in a daisy chain.

  Similarly, the head driving unit 72 drives the head 82 driven by the head driving unit 72 based on the received image signal 11 and the ejection timing signal 17, and the received image signal 11 and the ejection timing signal 17 are adjacently connected in a daisy chain. Transmit to the head drive unit 73.

  In this way, (n−1) head drive units 7 connected in a daisy chain until the image signal 11 and the ejection timing signal 17 reach the last head drive unit 7n of the n head drive units 7. Via. Accordingly, the image signal 11 and the ejection timing signal 17 include various electrical characteristics (for example, inductance, capacitance, resistance, etc.) due to the length of the transmission path (transmission path length) through which each signal is transmitted and the number of connectors through which the signal is transmitted. Delay due to the conductance component, etc.).

  In particular, since the ejection timing signal 17 is a signal for controlling the ink ejection timing at the head 8, if a delay occurs in the ejection timing signal 17, a deviation occurs in the ink ejection timing between the heads, resulting in a printing error. appear. Since the image signal 11 is temporarily stored in the head driving unit 7 and then output toward the head 8 in accordance with the ejection timing signal 17, there is no influence even if a delay occurs.

  FIG. 8 is a schematic diagram showing an example of a defect in the above-described conventional droplet discharge system.

  In FIG. 8, each of the n heads 8 has m nozzles arranged in a straight line, and the n heads 8 (heads 81 to 8n) are aligned in the nozzle arrangement direction. Has been placed. Therefore, when ink is ejected simultaneously from all (n × m) nozzles, or when the print medium 9 is stationary, the dots of ink ejected from the nozzles are in a straight line (for example, the line in the figure). L1).

  However, for example, when printing is performed while the print medium 9 is moved in the direction of arrow A in the figure for high-speed printing, a delay occurs in the ejection timing signal 17 of each head 8 due to the delay due to the daisy chain connection described above. The ink dots of the head 81 where the ejection operation is performed first are ejected on the line L1 in the figure, but the ink dots of the head 82 where the ejection operation is performed next are delayed by Δd1 due to the delay, The ink is discharged on the line L2 in the figure.

  Similarly, the ink dot of the head 8n that is finally subjected to the ejection operation is ejected onto the line Ln in the drawing with the printing position delayed by (n−1) × Δd1 due to the delay. In this way, there is a problem in that the positions of the ink dots that should be ejected on a straight line are shifted and printed as diagonal lines.

  As can be seen from FIG. 8, the greater the number of head drive units 7 connected in a daisy chain, the greater the delay of the ejection timing signal 17 and the greater the amount of printing misalignment. Further, as the transport unit 4 moves at a higher speed, the delay of the discharge timing signal 17 has an adverse effect on the printing result, and even when the transport unit 4 is moved at a higher speed in the future, even a small discharge timing deviation may occur. Needless to say, it has a big impact. Further, as the nozzles of the head 8 are further miniaturized and the area printed with the ink ejected from the nozzles is smaller, even if the ejection timing is the same, the printing is adversely affected.

  In order to solve this problem, it is conceivable to temporarily stop the movement of the print medium when ejecting ink. However, in this method, since the movement of the print medium is stopped every time ink is ejected, high-speed printing cannot be performed. In addition, by repeating the movement and stop of the print medium, unevenness occurs in the movement accuracy of the print medium, and the printing quality is deteriorated.

  Therefore, for example, in Patent Document 1, in the case of high-speed transmission of data by the block synchronization method, an appropriate delay time to be inserted between each step of the data transmission processing is quickly obtained and inserted at the time of data transmission, and transmission error occurs. A method for preventing this is presented.

Further, for example, in Patent Document 2, a method of wirelessly transmitting a droplet discharge timing in order to prevent various cables from being tangled with a moving means of the head and disconnecting the head or causing a defective movement of the head. Is presented.
Japanese Patent Laid-Open No. 7-253945 JP 2007-136258 A

  However, in the method of Patent Document 1, it is difficult to obtain the actual delay time itself, and the delay time varies depending on environmental conditions such as temperature and humidity. Therefore, it is very difficult to set an appropriate delay time.

  Further, in the method of Patent Document 2, the timing of ejecting a wirelessly transmitted droplet is an image signal itself generated based on bitmap image data, and wirelessly transmits a large-capacity image signal at high speed. A new technical problem arises. In addition, the method disclosed in Patent Document 2 is a case where the control unit and the head drive unit have a one-to-one configuration, and the problem caused by the delay caused by the daisy chain connection between the plurality of head drive units described above. It is not a solution.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a droplet discharge system capable of printing at high speed while moving a print medium with a simple system that eliminates a deviation in ink discharge timing between heads during printing. The purpose is to do.

  The object of the present invention can be achieved by the following constitution.

1. An operation unit for generating and transmitting image signals;
A transport unit that moves the print medium and generates and transmits a movement amount signal indicating the amount of movement of the print medium;
Based on the movement amount signal, an ejection timing signal generation unit that generates an ejection timing signal for controlling the timing of ejecting ink, an ejection timing signal transmission unit that transmits the ejection timing signal, and the operation unit that receives the ejection timing signal A control unit having an image signal storage unit for storing an image signal and an image signal transmission unit for transmitting the image signal;
A print data storage unit that stores at least a part of the image signal received from the control unit as print data, a discharge timing signal reception unit that receives the discharge timing signal from the control unit, and the print data based on the print data A plurality of heads having a head drive unit that performs ink ejection control in synchronization with an ejection timing signal, and a daisy chain connection unit that transmits the image signal received from the control unit to a subsequent head drive unit via a daisy chain connection A drive unit;
In a droplet discharge system comprising a plurality of heads driven by a plurality of head drive units,
Between the control unit and the plurality of head drive units,
A droplet discharge system, wherein the discharge timing signal is communicated by a connection method different from daisy chain connection.

  2. 2. The droplet discharge system according to 1, wherein the connection method different from the daisy chain connection is a method of connecting the control unit and each of the plurality of head drive units with a single cable.

  3. The connection method different from the daisy chain connection is a method of connecting the control unit and each of the plurality of head drive units with cables having the same electrical characteristics and the same wiring length. The droplet discharge system according to 2.

4). The ejection timing signal transmission unit and the ejection timing signal reception unit have an optical communication unit,
2. The droplet discharge system according to claim 1, wherein the connection method different from the daisy chain connection is a method of connecting the control unit and each of the plurality of head drive units with an optical communication cable.

5. The discharge timing signal transmission unit and the discharge timing signal reception unit have a wireless communication unit,
2. The droplet discharge system according to 1, wherein the connection method different from the daisy chain connection is a method of connecting the control unit and each of the plurality of head drive units by wireless communication.

  6). 6. The droplet discharge system according to 5, wherein the wireless connection method is any one of infrared communication, Bluetooth, and ZigBee.

  According to the present invention, an image signal is communicated by a daisy chain connection, and an ejection timing signal is communicated by a connection method different from the daisy chain connection. The system can provide a droplet discharge system capable of printing at high speed while moving a print medium.

  Hereinafter, the present invention will be described based on the illustrated embodiment, but the present invention is not limited to the embodiment. In the drawings, the same or equivalent parts are denoted by the same reference numerals, and redundant description is omitted.

  First, a first embodiment of a droplet discharge system of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing the configuration of the first embodiment.

  In FIG. 1, a droplet discharge system 1 includes an operation unit 2, a printing device 3, and the like.

  The operation unit 2 includes, for example, a personal computer (PC) (not shown), a monitor, a keyboard, a mouse, and the like, generates an image to be printed, converts the image into image data suitable for printing by the printing apparatus 3, and The image data is transmitted to the printing apparatus 3 as an image signal 11.

  The printing apparatus 3 includes a transport unit 4, a control unit 5, a printing unit 6, and the like.

  The transport unit 4 includes a transport unit 41, a movement amount signal generation unit 42, and the like. The transport unit 41 carries the print medium 9 such as print paper, and transports and moves the print medium 9. The movement amount signal generation unit 42 generates a movement amount signal 15 indicating the movement amount of the print medium 9 from the driving amount of the transport unit 41 and transmits the movement amount signal 15 to the control unit 5.

  The control unit 5 generates an ejection timing signal 17 for ejecting ink at a predetermined timing based on the movement amount signal 15 received from the movement amount signal generation unit 42 of the transport unit 4. Transmission is performed toward each of the head driving units 7. Further, the control unit 5 stores the image signal 11 received from the operation unit 2 and transmits the image signal 11 toward the first head driving unit 71 among the plurality of head driving units 7 of the printing unit 6. An example of the internal configuration of the control unit 5 will be described in detail with reference to FIG.

  The printing unit 6 includes a plurality of (here, n: n is a positive integer) head driving units 7 and a plurality (here, n: n is a positive integer) heads 8 and the like.

  The head driving unit 7 stores data (print data) 19 of a portion to be printed by the head 8 controlled by the head drive unit 7 among the image signals 11 received from the control unit 5, and the ejection timing signal 17 received from the control unit 5. In synchronism, the head 8 is driven based on the stored print data 19. Further, the image signal 11 received from the control unit 5 is transmitted to the head drive unit 7 at the next stage through daisy chain connection. One example of the internal configuration of the head drive unit 7 will be described in detail with reference to FIG.

  The head 8 has n nozzles 8 each having a plurality of nozzles (here, m: m is a positive integer) and is driven by the head driving unit 7 to eject ink in accordance with the ejection timing signal 17. Then, printing is performed on the print medium 9 with the ejected ink dots.

  FIG. 2 is a block diagram showing an example of the internal configuration of the control unit 5.

  2, the control unit 5 includes an image signal receiving unit 51, an image signal storage unit 52, an image signal transmitting unit 53, a movement amount signal receiving unit 54, an ejection timing signal generating unit 55, an ejection timing signal transmitting unit 56, and the like. It comprises a plurality of connectors and the like for connecting the control unit 5 and other units.

  The image signal receiving unit 51 receives the image signal 11 from the operation unit 2, the image signal storage unit 52 stores the received image signal 11, and the image signal transmission unit 53 uses the stored image signal 11 to drive the head of the printing unit 6. Send to unit 7.

  The movement amount signal receiver 54 receives the movement amount signal 15 from the movement amount signal generator 42 of the transport unit 4. Based on the received movement amount signal 15, the discharge timing signal generation unit 55 generates the discharge timing signal 17 each time the print medium 9 moves by a printing unit movement amount (hereinafter referred to as a feed pitch). The ejection timing signal transmission unit 56 transmits the generated ejection timing signal 17 to the head driving unit 7 of the printing unit 6.

  FIG. 3 is a block diagram showing an example of the internal configuration of the head drive unit 7. Here, it is assumed that the plurality of head drive units 7 have the same configuration, and a head drive unit 71 that first receives the image signal 11 from the control unit 5 will be described as an example.

  In FIG. 3, a head drive unit 71 includes a print data receiving unit 7a, a print data storage unit 7b, an ejection timing signal receiving unit 7c, a head drive unit 7d, a daisy chain connecting unit 7f, and the like, and the head drive unit 71 and other units. And a plurality of connectors and the like.

  The print data receiving unit 7a selects the data of the portion to be printed by the head 81 controlled by the head driving unit 71 from the image signal 11 received from the control unit 5, and receives it as the print data 19, and the print data storage unit 7b. Stores the received print data 19, and transmits the stored print data 19 to the head drive unit 7d.

  The ejection timing signal receiving unit 7c receives the ejection timing signal 17 from the control unit 5, and transmits the received ejection timing signal 17 to the head driving unit 7d. Based on the print data 19, the head drive unit 7 d outputs a head drive signal 18 in synchronization with the ejection timing signal 17 to drive the nozzles of the head 81 to eject ink.

  The daisy chain connection portion 7 f receives the image signal 11 from the control unit 5 and transmits the received image signal 11 to the head drive unit 72 at the subsequent stage. Subsequent head drive units 72 to 7n do not receive the image signal 11 directly from the control unit 5, but receive the image signal 11 from the previous head drive unit by daisy chain connection.

  As described above, in the first embodiment, the image signal 11 and the ejection timing signal 17 are transmitted by the following method.

  The image signal 11 is generated by the operation unit 2, transmitted to the control unit 5, and stored in the control unit 5. The stored image signal 11 is transmitted to the head drive unit 71 that first receives the image signals 11 of the plurality of head drive units 7. The image signal 11 received by the head driving unit 71 is sequentially transmitted from the head driving unit 72 in the subsequent stage to the head driving unit 7n by daisy chain connection.

  Accordingly, the further the head drive unit 7 is, the more delay occurs in the image signal 11. However, with respect to the image signal 11, a necessary portion in each head drive unit 7 is temporarily stored as print data 19, and each head 8 is driven in synchronization with the ejection timing signal 17 based on the stored print data 19. Therefore, even if a delay occurs in the image signal 11, the print result is not affected.

  On the other hand, the ejection timing signal 17 is generated by the control unit 5 based on the movement amount signal 15 generated by the movement amount signal generation unit 42 of the transport unit 4 and transmitted in parallel to the n head drive units 71 to 7n. Is done. Accordingly, unlike the conventional example shown in FIG. 7, the ejection timing signal 17 is not delayed, and printing defects due to the delay of the ejection timing signal 17 do not occur.

  Accordingly, since the image signal 11 which is not affected by the delay is transmitted by daisy chain connection as in the conventional case, the wiring is not complicated. Further, since the ejection timing signal 17 is a simple timing signal and not a large-capacity signal like the image signal 11, even if it is inputted in parallel to each of the head drive units 71 to 7n, the wiring becomes complicated and the scale is increased. Never do.

  Furthermore, communication between each head drive unit connected in a daisy chain is made by converting the data to be transmitted into serial data and then communicating by a differential signal method called LVDS (Low Voltage Differential Signaling) method, thereby reducing the number of wires. It can be reduced, it is resistant to noise, and the wiring length can be increased. Actually, for example, a wiring of several meters is required between the control unit 5 and the head driving unit 7.

  As described above, according to the first embodiment, the image signal is transmitted by daisy chain connection as usual, and the ejection timing signal is transmitted from the control unit to each head driving unit in parallel, thereby generating the ejection timing signal. Since the delay can be prevented, it is possible to provide a droplet discharge system capable of printing at high speed while moving the print medium with a simple system by eliminating the deviation of the ink discharge timing between the heads during printing.

  Next, a second embodiment of the droplet discharge system of the present invention will be described with reference to FIG. FIG. 4 is a block diagram illustrating the configuration of the second embodiment.

  In FIG. 4, in the second embodiment, the ejection timing signal transmission unit 56 of the control unit 5 has an output terminal corresponding to each of the n head driving units 71 to 7n, and the ejection timing. The signal transmission unit 56 and the n head driving units 71 to 7n are connected one-to-one by cables 101, respectively. This is the only difference between the second embodiment and the first embodiment, and the rest is the same as the first embodiment.

  In the first embodiment, the ejection timing signal 17 is transmitted from the control unit 5 by wiring connected in parallel to each of the n head driving units 71 to 7n. Therefore, due to the arrangement of the control unit 5 and the n head drive units 71 to 7n, the head drive unit close to the control unit 5 and the head drive unit at a distant position still have the wiring length, that is, wiring resistance or wiring parasitic. There is a difference in capacitance and the like, and a slight delay due to the difference in wiring length remains. In ultra-high speed printing or the like, this slight delay may be a problem.

  On the other hand, in the second embodiment, the ejection timing signal transmission unit 56 has an output terminal corresponding to each of the n head drive units 71 to 7n, and the ejection timing signal transmission unit 56. And n head driving units 71 to 7n are connected to each other by a cable 101 on a one-to-one basis. Therefore, the delay due to the wiring length, that is, the wiring resistance, the parasitic capacitance of the wiring, etc. can be prevented, and the ejection timing signal can be prevented from being delayed.

  Furthermore, it is desirable that the cables 101 that connect the ejection timing signal transmission unit 56 and the n head driving units 71 to 7n on a one-to-one basis have the same electrical characteristics and the same wiring length. As a result, it is possible to prevent the ejection timing signal from being delayed due to various electrical characteristics resulting from the wiring length described above.

  As described above, according to the second embodiment, the control unit and n are connected by connecting the ejection timing signal transmitter of the control unit and the n head drive units in a one-to-one relationship with a cable. Delay due to wiring length, that is, wiring resistance, parasitic capacitance of wiring, etc. due to the arrangement with the individual head drive units can be prevented, and delay of the ejection timing signal can be prevented. Therefore, it is possible to provide a droplet discharge system capable of printing at high speed while moving the print medium with a simple system.

  Next, third and fourth embodiments of the droplet discharge system of the present invention will be described with reference to FIGS. FIG. 5 is a block diagram illustrating a configuration of the third embodiment.

  In FIG. 5, in the third embodiment, the ejection timing signal transmission unit 56 of the control unit 5 is an optical communication unit having an optical communication function. The ejection timing signal receiving unit 7c of each of the n head driving units 71 to 7n is also an optical communication unit having an optical communication function. The ejection timing signal transmission unit 56 that is an optical communication unit and the ejection timing signal reception unit 7 c that is an optical communication unit are connected by an optical communication cable 103. Since the optical communication cable is less affected by the electrical characteristics due to the wiring length than the electrical cable using the metal wire, the discharge timing signal 17 can be prevented from being delayed due to the electrical characteristics described above.

  FIG. 6 is a block diagram showing a configuration of the fourth embodiment.

  In FIG. 6, in the fourth embodiment, the ejection timing signal transmission unit 56 of the control unit 5 is a wireless communication unit having a wireless communication function. The ejection timing signal receiving unit 7c of each of the n head driving units 71 to 7n is also a wireless communication unit having a wireless communication function. And the discharge timing signal transmission part 56 which is a radio | wireless communication part, and the discharge timing signal reception part 7c which is a radio | wireless communication part are connected not by a cable but by radio | wireless communication.

  Specific wireless communication methods include communication methods that are good at short-range communication such as IrDA using infrared rays, Bluetooth (registered trademark), ZigBee (registered trademark), and that do not require complicated protocols. It is not limited to. As a result, the ejection timing signal 17 can be easily transmitted without delay.

  Compared with Patent Document 2 described above, the method of Patent Document 2 needs to transmit a large-capacity image signal wirelessly at high speed in order to transmit the image signal 11 itself in the present invention as a timing signal for ejecting droplets. Yes, complicated protocols such as high-speed communication and error detection are required. On the other hand, in the fourth embodiment, the image signal 11 is transmitted by daisy chain connection as in the prior art, and only the ejection timing signal 17 is wirelessly transmitted. Therefore, the capacity of the ejection timing signal 17 for wireless transmission is small, and high-speed communication and complicated protocols are not necessary.

  As described above, according to the third and fourth embodiments, the transmission timing signal is transmitted by optical communication or wireless communication, so that the wiring length depending on the arrangement of the control unit and the n head driving units, that is, Delays due to wiring resistance, wiring parasitic capacitance, etc. can be prevented, and delays in ejection timing signals can be prevented, eliminating deviations in ink ejection timing between heads during printing, and moving the print medium with a simple system. However, it is possible to provide a droplet discharge system capable of printing at high speed.

  As described above, according to the present invention, the image signal is communicated by daisy chain connection, and the ejection timing signal is communicated by a connection method different from daisy chain connection. Therefore, it is possible to provide a droplet discharge system that can print at high speed while moving the print medium with a simple system.

  It should be noted that the detailed configuration and detailed operation of each component constituting the droplet discharge system according to the present invention can be changed as appropriate without departing from the spirit of the present invention.

It is a block diagram which shows the structure of 1st Embodiment. It is a block diagram which shows an example of the internal structure of a control unit. It is a block diagram which shows an example of an internal structure of a head drive unit. It is a block diagram which shows the structure of 2nd Embodiment. It is a block diagram which shows the structure of 3rd Embodiment. It is a block diagram which shows the structure of 4th Embodiment. It is a block diagram which shows the structure of the conventional droplet discharge system. It is a schematic diagram which shows the example of the malfunction in the conventional droplet discharge system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Droplet discharge system 2 Operation unit 3 Printing apparatus 4 Conveyance unit 41 Conveyance part 42 Movement amount signal generation part 5 Control unit 51 Image signal reception part 52 Image signal storage part 53 Image signal transmission part 54 Moving parent number reception part 55 Discharge timing Signal generation unit 56 Discharge timing signal transmission unit 6 Printing unit 7 Head drive unit 7a Print data reception unit 7b Print data storage unit 7c Discharge timing signal reception unit 7d Head drive unit 7f Daisy chain connection unit 8 Head 9 Print medium 11 Image signal 15 Movement amount signal 17 Discharge timing signal 18 Head drive signal 19 Print data 101 Cable 103 Optical communication cable

Claims (6)

An operation unit for generating and transmitting image signals;
A transport unit that moves the print medium and generates and transmits a movement amount signal indicating the amount of movement of the print medium;
Based on the movement amount signal, an ejection timing signal generation unit that generates an ejection timing signal for controlling the timing of ejecting ink, an ejection timing signal transmission unit that transmits the ejection timing signal, and the operation unit that receives the ejection timing signal A control unit having an image signal storage unit for storing an image signal and an image signal transmission unit for transmitting the image signal;
A print data storage unit that stores at least a part of the image signal received from the control unit as print data, a discharge timing signal reception unit that receives the discharge timing signal from the control unit, and the print data based on the print data A plurality of heads having a head drive unit that performs ink ejection control in synchronization with an ejection timing signal, and a daisy chain connection unit that transmits the image signal received from the control unit to a subsequent head drive unit via a daisy chain connection A drive unit;
In a droplet discharge system comprising a plurality of heads driven by a plurality of head drive units,
Between the control unit and the plurality of head drive units,
A droplet discharge system, wherein the discharge timing signal is communicated by a connection method different from daisy chain connection. 2. The droplet discharge system according to claim 1, wherein the connection method different from the daisy chain connection is a method of connecting the control unit and each of the plurality of head drive units with a single cable. . The connection method different from the daisy chain connection is a method of connecting the control unit and each of the plurality of head drive units with cables having the same electrical characteristics and the same wiring length. 3. The droplet discharge system according to 1 or 2. The ejection timing signal transmission unit and the ejection timing signal reception unit have an optical communication unit,
2. The droplet discharge system according to claim 1, wherein the connection method different from the daisy chain connection is a method of connecting the control unit and each of the plurality of head drive units with an optical communication cable. The discharge timing signal transmission unit and the discharge timing signal reception unit have a wireless communication unit,
2. The droplet discharge system according to claim 1, wherein the connection method different from the daisy chain connection is a method of connecting the control unit and each of the plurality of head drive units by wireless communication. 6. The droplet discharge system according to claim 5, wherein the wireless connection method is any one of infrared communication, Bluetooth, and ZigBee.

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