JP7464015B2 - HEAD SYSTEM, LIQUID EJECTION APPARATUS, AND LIQUID EJECTION METHOD - Google Patents

Description

This technology relates to a head system that ejects liquid from a nozzle, a liquid ejection device, and a liquid ejection method.

A printing device has been proposed that includes a control device and multiple liquid jet heads. The control device and multiple liquid jet heads are daisy-chained together via a single signal line. Each liquid jet head is equipped with a control circuit. The daisy-chain connection eliminates the need to individually connect the control device to each liquid jet head (see, for example, Patent Document 1).

JP 2009-184142 A

In the above conventional technology, one line of print data and liquid ejection timing data related to this print data are sequentially transmitted from the control device to multiple liquid ejection heads via a single signal line. However, when transmitting a large amount of print data, the configuration in which one line of print data and liquid ejection timing data are sequentially transmitted limits the amount of print data that can be transmitted per unit time, preventing the printing speed from being increased.

This disclosure has been made in consideration of these circumstances, and aims to provide a head system, a liquid ejection device, and a liquid ejection method that can improve printing speed.

A head system according to an embodiment of the present disclosure includes a main control circuit having a first counter and a plurality of head modules having nozzles, each of the plurality of head modules includes a sub-control circuit having a second counter, the main control circuit and each of the sub-control circuits are connected in series via a communication cable, the main control circuit executes a process of transmitting an image signal to each of the sub-control circuits via the communication cable, and each of the sub-control circuits executes a first ejection process of ejecting liquid from the nozzle of the head module to which it is connected each time the second counter it owns reaches a counter value indicating the passage of a first predetermined period when the transport speed of the recording medium on which the liquid ejected from the nozzle is equal to or higher than a predetermined speed.

A liquid ejection device according to one embodiment of the present disclosure includes the head system described above and a conveying device that conveys the recording medium.

In a liquid ejection method of a head system according to an embodiment of the present disclosure, the head system includes a main control circuit having a first counter and a plurality of head modules having nozzles, each of the plurality of head modules includes a sub-control circuit having a second counter, the main control circuit and each of the sub-control circuits are connected in series via a communication cable, the main control circuit executes a process of transmitting an image signal to each of the sub-control circuits via the communication cable, and each of the sub-control circuits executes a first ejection process of ejecting liquid from the nozzle of the head module to which it is connected each time the second counter of the sub-control circuit itself reaches a counter value indicating the passage of a first predetermined period when the transport speed of a recording medium recorded by the liquid ejected from the nozzle is equal to or higher than a predetermined speed.

In the head system, liquid ejection device, and liquid ejection method according to an embodiment of the present disclosure, when the transport speed of the recording medium is equal to or greater than a predetermined speed, each sub-control circuit ejects liquid from a nozzle each time its own second counter reaches a counter value indicating the passage of a first predetermined period. In other words, each sub-control circuit can eject liquid without a synchronization signal for ejection. Therefore, the main control circuit can continuously send image signals for multiple lines to the sub-control circuit, improving printing speed.

FIG. 2 is a schematic plan view of the printer. FIG. 2 is a block diagram of a control device, an encoder, and an inkjet head. FIG. 11 is an explanatory diagram illustrating a delay time caused by data transfer between a main control circuit and multiple SoCs. 6 is a graph showing a relationship between the transport speed of the recording paper by the transport roller and time. 11 is an explanatory diagram illustrating the relationship between the transmission and reception of a synchronization signal and image data and a count value between time 0 and time t1. FIG. 11 is an explanatory diagram illustrating the relationship between the transmission and reception of a synchronization signal and image data and a count value between time t1 and time t2; FIG. 5 is a flowchart illustrating a first ejection process and a second ejection process performed by a main control circuit. 5 is a flowchart illustrating an abnormality process performed by a main control circuit.

The present invention will be described below with reference to the drawings showing a printer according to an embodiment. FIG. 1 is a simplified plan view of the printer 1. In FIG. 1, the conveying direction of the recording paper 100 corresponds to the front-rear direction of the printer 1. The width direction of the recording paper 100 corresponds to the left-right direction of the printer 1. The direction perpendicular to the front-rear and left-right directions, i.e., the direction perpendicular to the paper surface of FIG. 1, corresponds to the up-down direction of the printer 1. The left-right direction corresponds to the first direction, and the front-rear direction corresponds to the second direction. The printer 1 corresponds to a liquid ejection device.

As shown in FIG. 1, the printer 1 includes a platen 3 housed in a case 2, four inkjet heads 4, two transport rollers 5 and 6, and a control device 7. The printer 1 corresponds to a liquid ejection device, and the transport rollers 5 and 6 correspond to a transport machine.

The recording paper 100 passes over the upper surface of the platen 3. The four inkjet heads 4 are lined up in the transport direction above the platen 3. Each inkjet head 4 is a so-called line-type head. Ink is supplied to the inkjet heads 4 from an ink tank (not shown). The four inkjet heads 4 are supplied with ink of different colors.

As shown in FIG. 1, the two transport rollers 5 and 6 are disposed on the rear and front sides, respectively, of the platen 3. The two transport rollers 5 and 6 are each driven by a motor (not shown) to transport the recording paper 100 on the platen 3 forward.

The control device 7 includes an FPGA, an EEPROM, a RAM, etc. The control device 7 may also include a CPU, an ASIC, etc. The control device 7 is connected to an external device 9 such as a PC so as to be able to communicate data with the external device 9, and controls each part of the printer 1 based on the print data sent from the external device 9.

Figure 2 is a block diagram of the control device 7, the encoder 8, and the inkjet head 4. The control device 7 includes a main control circuit 7a. The main control circuit 7a includes a counter 7b, a communication unit 7c, and a memory unit 7d. The inkjet head 4 includes a plurality of head modules 40. The plurality of head modules 40 are arranged in a row in the left-right direction.

The multiple head modules 40 include, for example, a first head module 40(1), a second head module 40(2), ..., an nth head module 40(n) (n is a natural number). The first head module 40(1) is located on the leftmost side, and the nth head module 40(n) is located on the rightmost side.

Each of the first head module 40(1) to the nth head module 40(n) includes a SoC 41 and multiple heads 42. The SoC 41 corresponds to a sub-control circuit. The heads 42 have multiple nozzles. The SoC 41 includes a control unit 41a, a memory unit 41b, a counter 41c, and a communication unit 41d. The control unit 41a controls the operation of the SoC 41. The memory unit 41b is, for example, a rewritable non-volatile memory such as an EPROM or an EEPROM. Hereinafter, the SoCs 41 of the head module 40(1) to the nth head module 40(n) will be referred to as SoC(1) to SoC(n).

The communication unit 7c and each communication unit 41d are connected in series by a communication cable 50. The communication unit 7c transmits image data included in the print data to the communication unit 41d of SoC(1). The image data corresponds to an image signal. The communication unit 41d of SoC(1) transfers the image data to the communication unit 41d of SoC(2), which transfers it to the communication unit 41d of SoC(3). In this way, the image data is transferred in order up to the communication unit 41d of SoC(n).

The image data includes the identifiers of each of SoC(1) to SoC(n) and print information linked to each identifier. The control units 41a of SoC(1) to SoC(n) obtain the image information linked to their own identifiers from the received image data.

The transport rollers 5 and 6 are equipped with motors (not shown), and the motors are provided with an encoder 8. The encoder 8 detects the rotational position of the motor. The rotational position of the motor corresponds to the front and rear positions of the recording paper 100, and the encoder 8 sends a synchronization signal to the main control circuit 7a each time it detects a rotational position corresponding to the printing position (the position on the recording paper 100 where one line should be printed).

The main control circuit 7a transmits a synchronization signal to the communication unit 41d of SoC(1) as necessary. The communication unit 41d of SoC(1) transfers the synchronization signal to the communication unit 41d of SoC(2), which transfers it to the communication unit 41d of SoC(3). In this way, the synchronization signal is transferred in order up to the communication unit 41d of SoC(n).

Figure 3 is an explanatory diagram explaining the delay time caused by data transfer between the main control circuit 7a and multiple SoCs 41. The consecutive numbers in Figure 3 indicate the count values of the counter 7b of the main control circuit 7a and the counter 41c of each SoC 41. The counters 7b, 41c are synchronized, for example, by inputting a reset signal from outside to each counter 7b in parallel. Alternatively, the main control circuit 7a may continue to send a reset signal to each counter 7b, 41c via the communication cable 50 for a predetermined time, resetting and synchronizing each counter 7b, 41c simultaneously.

The counters 7b and 41c of the main control circuit 7a may be used as the master clock and the counter 41c of the SoC 41 may be used as the slave clock, and the counters 7b and 41c may be reset and synchronized simultaneously based on the Precision Time Protocol (PTP). Also, the counters 7b and 41c may be reset and synchronized simultaneously based on the Network Time Protocol (NTP), i.e. by having the counters 7b and 41c receive time information from an NTP server.

To measure the delay time caused by the data transfer, the main control circuit 7a transfers a test synchronization signal to SoC 41(1). At this time, the main control circuit 7a links the count value at the time of transfer (for example, "5") to its own identifier and transfers it together with the synchronization signal to SoC(1). Hereinafter, the count value and identifier will be referred to as count value information, and count value information having the identifier of the main control circuit 7a will be referred to as count value information (0), and count value information having the identifier of SoC(n) will be referred to as count value information (n).

SoC (1) transfers the received synchronization signal to SoC (2). At this time, SoC (1) transfers count value information (0) and the count value of its own counter at the time of transfer (e.g., "6") and count value information (1) linked to its own identifier together with the synchronization signal to SoC (2).

SoC (2) transfers the received synchronization signal to SoC (3). At this time, SoC (2) transfers count value information (0), count value information (1), the count value of its own counter at the time of transfer (e.g., "7"), and count value information (2) linked to its own identifier, together with the synchronization signal to SoC (3). In this way, the synchronization signal and each count value information are transferred up to the most downstream SoC (n).

In addition, SoC(n) transfers its own count value information (n) upon receiving the synchronization signal to SoC(n-1), and SoC(n-1) transfers count value information (n) and count value information (n-1) to SoC(n-2). In this way, each piece of count value information is transferred up to the most upstream SoC(1).

As a result, each SoC 41 can obtain the count value at which it and all other SoCs 41 receive the synchronization signal. Each SoC 41 can calculate the delay time caused by the transfer between itself and the SoC 41 to which it transfers data. Therefore, each SoC 41 can recognize the SoC 41 that will receive data latest, and can cause liquid to be ejected from each head module 40 simultaneously at the time when the SoC 41 that will receive data latest receives the synchronization signal.

For example, in FIG. 3, SoC 41 that receives data latest is SoC(n). If the count value at the time when SoC(n) receives the synchronization signal is "10", then for SoC(1), the time when it receives the synchronization signal is "6", so the count value from when it receives the synchronization signal until SoC(n) receives the synchronization signal, i.e., the delay amount, is 4. For SoC(2), the time when it receives the synchronization signal is "7", so the delay amount from when it receives the synchronization signal until SoC(n) receives the synchronization signal is 3. In this way, SoC(1) to SoC(n-1) obtain their respective delay amounts. By delaying by their own delay amounts from the time when SoC(1) to SoC(n-1) receive the synchronization signal, liquid can be ejected simultaneously from each head module 40.

Figure 4 is a graph that shows a schematic relationship between the transport speed of the recording paper 100 by the transport rollers 5 and 6 and time. In Figure 4, Vmax indicates the maximum transport speed. As shown in Figure 4, the transport speed increases proportionally from transport start time 0 to time t1, reaches the maximum speed at time t1, and maintains the maximum speed from time t1 to time t2. It decreases proportionally from time t2, and becomes 0 at time t3.

Figure 5 is an explanatory diagram that explains the relationship between the transmission and reception of synchronization signals and image data and the count values between time 0 and time t1. In Figure 5, the numbers on the left indicate the count values of counters 7b and 41c. The arrows indicate the transmission and reception of synchronization signals, with the main control circuit 7a receiving a synchronization signal from the encoder 8 and transmitting the synchronization signal to SoC (1). SoC (k) (k = 1 to n-1) transmits the synchronization signal it has received to SoC (k+1). In Figure 5, data indicates the image data received by the main control circuit 7a and SoC 41.

As shown in FIG. 5, for example, when the count value is 104, the main control circuit 7a receives a synchronization signal from the encoder 8, and when the count value is 105, it transmits a synchronization signal to SoC (1). The synchronization signal is transferred to SoC (n), which receives the synchronization signal when the count value is 110. When the count value is 110, SoC (1) to SoC (n) simultaneously eject one line of ink from the head 42. Note that before the count value is 104, the main control circuit 7a and each SoC 41 have received at least one line of image data. For example, if the synchronization signal and the image data are not linked, SoC (1) ejects one line of ink from the nozzle at the count value of 110 based on the one line of image data that was received earliest among the one line or more of image data that was received and stored at the time of receiving the synchronization signal (at the time of count value 105). For example, if a synchronization signal is associated with one line of image data, SoC(1) receives the synchronization signal immediately before it receives it (when the count value is 105), and based on the stored one line of image data, ejects one line of ink from the nozzles when the count value is 110. The same is true for SoC(2) to SoC(n). A predetermined length of waiting time is provided before and after the main control circuit 7a and SoC(1) to SoC(n) send a synchronization signal, and no image data is sent or received during the waiting time.

The main control circuit 7a receives multiple lines of image data from the external device 9 while the count value is between 106 and 125. Hereinafter, one line of image data will also be referred to as one packet. The main control circuit 7a sequentially transmits multiple packets one by one to SoC (1). SoC (1) sequentially transmits the received packets to SoC (2). In the same manner, SoC (2) to SoC (n-1) sequentially transmit the received packets to the downstream SoC 41.

As shown in FIG. 5, the packets received by the upstream main control circuit 7a or SoC 41 include packets that have not yet been sent to the downstream SoC 41, so the number of packets received upstream is greater than the number of packets received downstream.

When the count value is 134, the main control circuit 7a receives a synchronization signal from the encoder 8 and transmits it downstream, and when the count value is 140, each SoC(1) to SoC(n) simultaneously ejects one line's worth of ink from the head 42. Between the count value of 136 and when the main control circuit 7a receives the next synchronization signal, it receives multiple packets from the external device 9 and transmits them downstream.

When the count value is 159, the main control circuit 7a receives a synchronization signal from the encoder 8 and transmits it downstream, and when the count value is 165, each SoC(1) to SoC(n) simultaneously ejects one line's worth of ink from the head 42. Between the count value of 161 and when the main control circuit 7a receives the next synchronization signal, it receives multiple packets from the external device 9 and transmits them downstream.

When the count value is 179, the main control circuit 7a receives a synchronization signal from the encoder 8 and transmits it downstream, and when the count value is 185, each SoC(1) to SoC(n) ejects one line's worth of ink from the head 42 simultaneously.

In FIG. 5, between time 0 and time t1, i.e., while the conveying speed is increasing, the main control circuit 7a receives a synchronization signal from the encoder 8. Since the conveying speed changes over time, the time between when the main control circuit 7a receives one synchronization signal and when it receives the next synchronization signal, i.e., the period during which the synchronization signal is received, is not constant but gradually becomes shorter. For example, as described above, the main control circuit 7a receives synchronization signals when the count values are 104, 134, 159, and 179, so the periods are 30, 25, and 20. In other words, the main control circuit 7a executes a third transmission process that transmits synchronization signals to each SoC 41 via the communication cable 50 at time intervals according to the conveying speed.

As described above, when each SoC 41 receives a synchronization signal, it causes liquid to be ejected from each head module 40 simultaneously by delaying the time by its own delay amount from the time of receiving the synchronization signal. That is, each time each SoC 41 receives a synchronization signal transmitted in the third transmission process, it executes a fourth ejection process that ejects liquid from the nozzles of the head module 40 to which it is connected at a predetermined time based on the received synchronization signal.

While the conveying speed is increasing, it is below the maximum speed, and the period during which the main control circuit 7a receives the synchronization signal is longer than the period from time t1 to time t2, i.e., the period during which the maximum speed is maintained, and a large number of packets can be transmitted during that period.

As in the period from time 0 to time t1, from time t2 to time t3, i.e., while the conveying speed is decreasing, the main control circuit 7a sequentially transmits the received synchronization signal downstream, and sequentially transmits multiple packets downstream during the period in which the main control circuit 7a receives the synchronization signal. While the conveying speed is decreasing, the conveying speed is below the maximum speed, and the period in which the main control circuit 7a receives the synchronization signal is longer than the period from time t1 to time t2, allowing a large number of packets to be transmitted during the period. While the conveying speed is decreasing, the main control circuit 7a executes a third transmission process that transmits a synchronization signal to each SoC 41 via the communication cable 50 at time intervals according to the conveying speed, and each SoC 41 executes a fourth ejection process.

Figure 6 is an explanatory diagram explaining the relationship between the transmission and reception of the synchronization signal and image data and the count value between time t1 and time t2. Between time t1 and time t2, the conveying speed maintains the maximum speed (see Figure 4). Compared to between time 0 and time t1 and between time t2 and time t3, i.e., while the conveying speed is increasing and decreasing, the period during which the main control circuit 7a receives the synchronization signal while the conveying speed maintains the maximum speed is short, and the number of packets that the main control circuit 7a can receive during that period is small. Therefore, while the conveying speed maintains the maximum speed, the main control circuit 7a reduces the number of times it transmits the synchronization signal downstream, reducing the waiting time before and after transmitting the synchronization signal, and enabling the main control circuit 7a and SoC(1) to SoC(n) to transmit and receive a large number of packets.

As shown in FIG. 6, for example, every 15 counts, that is, every time the first predetermined period for transmitting the synchronization signal has elapsed, the synchronization signal is transmitted from the encoder 8 to the main control circuit 7a, and the main control circuit 7a receives the synchronization signal when the count value is 104, 119, 134, 149, and 164. The main control circuit 7a transmits only the synchronization signal received when the count value is 104 and 164 to each SoC 41. That is, the main control circuit 7a executes a first transmission process to transmit a synchronization signal to each SoC 41 via the communication cable 50 to synchronize the ejection time when the liquid is ejected from the nozzle every time a second predetermined period, which is a predetermined multiple of the first predetermined period, has elapsed. Here, the second predetermined period is 60 counts, which is four times the first predetermined period (15 counts), but the predetermined multiple is not limited to four times, and may be three times or less or five times or more.

When the count value is 119, 134, or 149, the main control circuit 7a does not transmit the received synchronization signal downstream, reducing the number of times the synchronization signal is transmitted and reducing waiting time. Therefore, when the count value is between 104 and 164, the main control circuit 7a can continuously receive and transmit a large number of packets.

As described above, when each SoC 41 receives a synchronization signal, it causes liquid to be ejected from each head module 40 simultaneously by delaying by its own delay amount from the time of receiving the synchronization signal. In other words, when each SoC 41 receives a synchronization signal from the main control circuit 7a each time the second predetermined period elapses, it executes a second ejection process that ejects liquid from the nozzles of the head module 40 to which it is connected at a predetermined time based on the received synchronization signal.

The main control circuit 7a does not transmit the received synchronization signal downstream when the count value is 119, 134, or 149. Even if each SoC 41 does not receive a synchronization signal, it refers to its own counter 41c, and executes a first ejection process to eject liquid from the nozzle of the head module to which it is connected every time 15 counts have elapsed since the earliest point in time when liquid was ejected in response to the reception of a synchronization signal, that is, every time the value of its own counter 41c reaches a counter value indicating the passage of a first predetermined period. For example, if the count value at the earliest point in time when liquid was ejected in response to the reception of a synchronization signal is 110, each SoC 41 ejects liquid simultaneously when the value of its own counter 41c reaches 125, 140, or 155.

Figure 7 is a flowchart explaining the first and second ejection processes by the main control circuit 7a. The main control circuit 7a calculates and acquires the conveying speed based on the rotational position of the motor detected by the encoder 8 (S1). The main control circuit 7a determines whether the conveying speed is equal to or greater than a threshold speed (S2). The threshold speed is, for example, a value slightly smaller than the maximum speed Vmax, and is stored in advance in the memory unit 7d of the main control circuit 7a.

If the transport speed is not equal to or greater than the threshold speed (S2: NO), the main control circuit 7a executes the third transmission process (S3) and causes each SoC 41 to execute the fourth ejection process (S4, see FIG. 5). Each SoC 41 ejects ink from the nozzle at a predetermined time based on the received synchronization signal. The main control circuit 7a determines whether printing has finished (S5). If printing has not finished (S5: NO), the main control circuit 7a returns the process to step S2.

In step S2, if the conveying speed is equal to or greater than the threshold speed (S2: YES), the main control circuit 7a determines whether the time interval for receiving the synchronization signal from the encoder 8 is within an allowable time interval, for example, 13 to 17 counts, i.e., whether the conveying speed is abnormal (S6). If the time interval for receiving the synchronization signal from the encoder 8 is not within the allowable time interval, i.e., if the conveying speed is abnormal (S6: YES), the main control circuit 7a executes abnormality processing (S9), which will be described later, and proceeds to step S5.

If the transport speed is not abnormal (S6: NO), the main control circuit 7a executes a first transmission process (S7) and causes each SoC 41 to execute a first and second ejection process (S8, see FIG. 6). Each SoC 41 ejects ink from a nozzle at a predetermined time based on the received synchronization signal, and ejects liquid from the nozzle of the head module 40 to which it is connected each time its own counter 41c reaches a counter value indicating the passage of a first predetermined period. The main control circuit 7a proceeds to step S5. If printing is completed in step S5 (S5: YES), the main control circuit 7a ends the process.

Figure 8 is a flowchart explaining the abnormality processing by the main control circuit 7a. The main control circuit 7a executes the second transmission process (S11) and causes the SoC 41 to execute the third discharge process (S12). That is, the main control circuit 7a switches from the first and second discharge processes to the third discharge process. The second transmission process is a process similar to the third transmission process. The third discharge process is a process similar to the fourth discharge process.

The main control circuit 7a determines whether the conveying speed is abnormal (S13). If the conveying speed is abnormal (S13: YES), the process returns to step S11 and the second transmission process and the third ejection process are maintained. If the conveying speed is not abnormal in step S13 (S13: NO), the main control circuit 7a stops the third ejection process (S14), ends the abnormality process, and returns to step S5 (see FIG. 7).

In the printer 1 according to the embodiment, when the transport speed of the recording paper 100 is equal to or faster than a predetermined speed, each SoC 41 ejects liquid from a nozzle each time its own counter 41c reaches a counter value indicating the passage of a first predetermined period. In other words, each SoC 41 can eject liquid without a synchronization signal for ejection. Therefore, the main control circuit 7a can continuously send image signals for multiple lines to the SoC 41, improving the printing speed.

The embodiments disclosed herein are illustrative in all respects and should not be considered limiting. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of the claims and equivalents to the scope of the claims.

1. Printer (liquid ejection device)
5, 6 Conveyor roller (conveyor)
7a Main control circuit 7b Counter (first counter)
40 Head module 41 SoC (sub-control circuit)
41c counter (second counter)
50 Communication cable

Claims (10)

a main control circuit having a first counter;
a plurality of head modules each having a nozzle;
Each of the plurality of head modules includes a sub-control circuit having a second counter,
The main control circuit and each of the sub-control circuits are connected in series via a communication cable,
The main control circuit executes a process of transmitting an image signal to each of the sub-control circuits via the communication cable,
each of the sub-control circuits executes a first ejection process for ejecting liquid from the nozzles of the head module to which the sub-control circuit is connected each time the second counter of the sub-control circuit reaches a counter value indicating the passage of a first predetermined period, when a transport speed of a recording medium on which recording is performed by the liquid ejected from the nozzles is equal to or higher than a predetermined speed ;
the main control circuit executes a first transmission process to transmit a synchronization signal for synchronizing the ejection time points at which liquid is ejected from the nozzles via the communication cable to each of the sub-control circuits each time a second predetermined period, which is a predetermined multiple of the first predetermined period, elapses;
A head system in which, when each of the sub-control circuits receives the synchronization signal, it executes a second ejection process to eject liquid from the nozzles of the head module to which it is connected at a predetermined time based on the received synchronization signal . The main control circuit includes:
Execute a process of acquiring the conveying speed,
Execute a process of determining whether the acquired conveying speed is an abnormal speed or not;
When it is determined that the conveying speed is the abnormal speed, a second transmission process is executed to transmit the synchronization signal to each of the sub-control circuits via the communication cable at a time interval corresponding to the conveying speed.
The head system described in claim 1, wherein each of the sub-control circuits executes a third ejection process to eject liquid from the nozzles of the head module to which it is connected at a predetermined time based on the received synchronization signal each time it receives the synchronization signal transmitted in the second transmission process. The head system according to claim 2 , wherein each of the sub-control circuits stops the third ejection process when the main control circuit determines that the transport speed is not the abnormal speed after the third ejection process is executed. the main control circuit executes a third transmission process to transmit the synchronization signal to each of the sub-control circuits via the communication cable at a time interval corresponding to a transport speed of a recording medium on which recording is performed by the liquid ejected from the nozzles when the transport speed of the recording medium is less than a predetermined speed;
A head system described in any one of claims 1 to 3, wherein each of the sub-control circuits executes a fourth ejection process to eject liquid from the nozzles of the head module to which it is connected at a predetermined time based on the received synchronization signal each time it receives the synchronization signal transmitted in the third transmission process. 5. The head system according to claim 1 , wherein each of the sub-control circuits executes a start point adjustment process for simultaneously starting counting by each of the second counters. the main control circuit executes a process of transmitting a reset signal for resetting the second counter via the communication cable;
The head system according to claim 5 , wherein the sub-control circuits simultaneously reset the second counters based on the received reset signal in the start point adjustment process. a main control circuit having a first counter;
A plurality of head modules each having a nozzle;
Equipped with
Each of the plurality of head modules includes a sub-control circuit having a second counter,
The main control circuit and each of the sub-control circuits are connected in series via a communication cable,
The main control circuit executes a process of transmitting an image signal to each of the sub-control circuits via the communication cable,
each of the sub-control circuits executes a first ejection process for ejecting liquid from the nozzles of the head module to which the sub-control circuit is connected each time the second counter of the sub-control circuit reaches a counter value indicating the passage of a first predetermined period, when a transport speed of a recording medium on which recording is performed by the liquid ejected from the nozzles is equal to or higher than a predetermined speed;
each of the sub-control circuits executes a start time adjustment process for simultaneously starting counting by each of the second counters;
In the start time adjustment process, the sub-control circuits simultaneously reset the second counters based on a Precision Time Protocol (PTP) or a Network Time Protocol (NTP).
Head system. A head system according to any one of claims 1 to 7 ;
a conveyor that conveys the recording medium. A liquid ejection method for a head system, comprising the steps of:
The head system comprises:
a main control circuit having a first counter;
A plurality of head modules each having a nozzle;
Equipped with
Each of the plurality of head modules includes a sub-control circuit having a second counter,
The main control circuit and each of the sub-control circuits are connected in series via a communication cable,
The main control circuit executes a process of transmitting an image signal to each of the sub-control circuits via the communication cable,
each of the sub-control circuits executes a first ejection process for ejecting liquid from the nozzles of the head module to which the sub-control circuit is connected each time the second counter of the sub-control circuit reaches a counter value indicating the passage of a first predetermined period, when a transport speed of a recording medium on which recording is performed by the liquid ejected from the nozzles is equal to or higher than a predetermined speed ;
the main control circuit executes a first transmission process to transmit a synchronization signal for synchronizing the ejection time points at which liquid is ejected from the nozzles via the communication cable to each of the sub-control circuits each time a second predetermined period, which is a predetermined multiple of the first predetermined period, elapses;
A liquid ejection method in which, when each of the sub-control circuits receives the synchronization signal, it executes a second ejection process to eject liquid from the nozzles of the head module to which it is connected at a predetermined time based on the received synchronization signal . A liquid ejection method for a head system, comprising the steps of:
The head system comprises:
a main control circuit having a first counter;
A plurality of head modules each having a nozzle;
Equipped with
Each of the plurality of head modules includes a sub-control circuit having a second counter,
The main control circuit and each of the sub-control circuits are connected in series via a communication cable,
The main control circuit executes a process of transmitting an image signal to each of the sub-control circuits via the communication cable,
each of the sub-control circuits executes a first ejection process for ejecting liquid from the nozzles of the head module to which the sub-control circuit is connected each time the second counter of the sub-control circuit reaches a counter value indicating the passage of a first predetermined period, when a transport speed of a recording medium on which recording is performed by the liquid ejected from the nozzles is equal to or higher than a predetermined speed;
each of the sub-control circuits executes a start time adjustment process for simultaneously starting counting by each of the second counters;
In the start time adjustment process, the sub-control circuits simultaneously reset the second counters based on a Precision Time Protocol (PTP) or a Network Time Protocol (NTP).
Liquid dispensing method.

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