JP2018051933A - Liquid ejection device - Google Patents

Abstract

When a short circuit occurs in a head unit, the location where the short circuit occurs is specified as the head unit. A liquid discharge head provided with a first head unit having a plurality of discharge units for discharging liquid, a processing circuit provided at a location different from the liquid discharge head, a power supply circuit for supplying power, and a power supply A relay node electrically connected to the circuit, a head power feeding unit for transmitting power supplied from the power supply circuit via the relay node to the first head unit, and a power supply circuit supplied via the relay node An external power feeding unit for transmitting electric power to the processing circuit; and a detection unit capable of detecting occurrence of a short circuit in the first head unit, wherein the head power feeding unit is electrically connected to the first head unit. 1 feed line and a first fuse electrically connected between the first feed line and the relay node, and the detection unit is short-circuited in the first head unit based on the potential of the first feed line. A liquid ejection apparatus for detecting the occurrence. [Selection] Figure 3

Description

  The present invention relates to a liquid ejection apparatus.

  A liquid discharge apparatus such as an ink jet printer drives a discharge unit provided in a head unit to discharge a liquid such as ink filled in a cavity of the discharge unit, thereby forming an image on a recording medium. Execute. The liquid ejection apparatus includes various components such as a conveyance mechanism for conveying the recording medium, a drive signal generation circuit that generates a drive signal for driving the ejection unit, and the various components. And a power supply circuit for supplying power (see Patent Document 1).

JP2015-182346A

  By the way, in recent years, in order to realize high-resolution printing, high-speed printing, and the like, there are cases in which a large number of ejection units are provided at high density in the head unit. And when a large number of ejection parts are provided in the head unit at a high density, there is a probability that a short circuit due to a failure or the like will occur in the head unit compared to a case where a small number of ejection parts are provided in the head unit at a low density. May be high. For this reason, from the viewpoint of maintainability, such as improvement of work efficiency in maintenance and shortening of work time, it is preferable that when a short circuit occurs in the head unit, it is possible to identify the location where the short circuit occurs in the head unit.

  The present invention has been made in view of the circumstances described above, and it is an object of the present invention to provide a technique for quickly identifying that a short-circuit occurrence point is a head unit when a short circuit occurs in the head unit. I will.

  In order to solve the above problems, a liquid discharge apparatus according to the present invention is provided in a location different from the liquid discharge head provided with the first head unit having a plurality of discharge portions for discharging liquid, and the liquid discharge head. Processing circuit, a power supply circuit for supplying power, a relay node electrically connected to the power supply circuit, and the power supplied from the power supply circuit via the relay node are transmitted to the first head unit. A head power supply unit for transmitting power, an external power supply unit for transmitting power supplied from the power supply circuit via the relay node to the processing circuit, and detection of occurrence of a short circuit in the first head unit A detection unit, wherein the head power supply unit is electrically connected between the first power supply line electrically connected to the first head unit, and between the first power supply line and the relay node. Comprising a first fuse that is, wherein the detection unit, based on the potential of the first power supply line, detects the occurrence of a short circuit in the first head unit, characterized in that.

  According to the present invention, the detection unit does not target the processing circuit but detects the short circuit for the first head unit. Therefore, when a short circuit occurs in the first head unit, the location where the short circuit occurs is the first. It becomes possible to quickly identify the head unit. For this reason, compared with the case where a detection part makes a processing circuit the object of short circuit detection, maintainability can be improved.

  In the liquid ejection apparatus described above, the first head unit may include at least 300 of the ejection units per inch.

  According to this aspect, when a large number of ejection portions are arranged in the first head unit at a high density and the probability of occurrence of a short circuit in the first head unit is high, the occurrence of a short circuit in the first head unit is quickly identified. can do. For this reason, compared with the case where a detection part makes a processing circuit the object of short circuit detection, maintainability can be improved.

  In the liquid ejection apparatus described above, the liquid ejection head includes a second head unit having a plurality of ejection units that eject liquid, and the head power feeding unit is a second electrically connected to the second head unit. A power supply line; and a second fuse electrically connected between the second power supply line and the relay node, wherein the detection unit is configured to perform the second operation based on a potential of the second power supply line. The occurrence of a short circuit in the head unit may be detected.

  According to this aspect, since the detection unit detects the short circuit for the second head unit, when the short circuit occurs in the second head unit, it is promptly determined that the location of the short circuit is the second head unit. It becomes possible to specify. That is, according to this aspect, when the liquid ejection head includes a plurality of head units, it is possible to specify the occurrence location of a short circuit in units of head units.

  In the liquid ejection apparatus described above, the liquid ejection head includes a second head unit having a plurality of ejection units that eject liquid, and the head power feeding unit is a second electrically connected to the second head unit. A power supply line, wherein the first fuse is electrically connected between the second power supply line and the relay node, and the detection unit is configured to detect the potential of the first power supply line or the potential of the second power supply line. The occurrence of a short circuit in at least one of the first head unit and the second head unit may be detected based on at least one of them.

  According to this aspect, the detection unit does not target the processing circuit, but detects the short circuit for the liquid discharge head including the first head unit and the second head unit, so the first head unit or the second head unit When a short circuit occurs at, it is possible to quickly identify that the location of the short circuit is the first head unit or the second head unit.

  The liquid ejecting apparatus described above includes an out-of-head short-circuit detecting unit capable of detecting occurrence of a short circuit in the processing circuit, and the out-of-head power feeding unit includes a third feeding line electrically connected to the processing circuit, A third fuse electrically connected between the third feeder and the relay node, and the out-of-head short-circuit detector is short-circuited in the processing circuit based on the potential of the third feeder. It is also possible to detect the occurrence of.

  According to this aspect, the out-of-head short-circuit detection unit detects a short circuit for the processing circuit, and thus, when a short circuit occurs in the processing circuit, quickly identifies that the short-circuit occurrence point is the processing circuit. It becomes possible.

1 is a block diagram illustrating an example of a configuration of an inkjet printer 1 according to the present invention. 1 is a perspective view illustrating an example of a schematic internal structure of an inkjet printer 1. FIG. 2 is an explanatory diagram for explaining an example of power supply to each component of the inkjet printer. FIG. 4 is an explanatory diagram for explaining an example of a structure of a discharge unit D. FIG. 4 is a plan view illustrating an example of an arrangement of nozzles N in the liquid discharge head 3. FIG. It is a block diagram showing an example of composition of head unit HU. 6 is a timing chart for explaining an example of a printing process. It is explanatory drawing for demonstrating an example of the relationship between the printing signal SI and connection state designation | designated signal SLa and SLb. 3 is a block diagram illustrating an example of a configuration of a drive signal supply circuit 31. FIG. It is explanatory drawing for demonstrating an example of the supply of the electric power with respect to each component of the inkjet printer 1T which concerns on contrast. 10 is an explanatory diagram for explaining an example of power supply to each component of the inkjet printer 1 according to Modification 1. FIG.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. However, in each figure, the size and scale of each part are appropriately changed from the actual ones. Further, since the embodiments described below are preferable specific examples of the present invention, various technically preferable limitations are attached thereto. However, the scope of the present invention is particularly limited in the following description. Unless otherwise stated, the present invention is not limited to these forms.

<< A. Embodiment >>
In the present embodiment, the liquid ejecting apparatus will be described by exemplifying an ink jet printer that ejects ink (an example of “liquid”) to form an image on a recording paper P (an example of “recording medium”).

<< 1. Overview of inkjet printers >>
The configuration of the inkjet printer 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. Here, FIG. 1 is a functional block diagram illustrating an example of the configuration of the inkjet printer 1 according to the present embodiment. FIG. 2 is a perspective view showing an example of a schematic internal structure of the ink jet printer 1.

  Print data Img indicating an image to be formed by the inkjet printer 1 is supplied to the inkjet printer 1 from a host computer (not shown) such as a personal computer or a digital camera. The ink jet printer 1 executes a printing process for forming an image indicated by the print data Img supplied from the host computer on the recording paper P. In addition, although mentioned later for details, in this embodiment, the case where the inkjet printer 1 is a line printer is assumed.

As illustrated in FIG. 1, the inkjet printer 1 includes a liquid ejection head 3 including a head unit HU provided with an ejection unit D that ejects ink, and a control unit 6 that controls the operation of each unit of the inkjet printer 1. A drive signal generation module 2 including a drive signal generation circuit 20 that generates a drive signal Com for driving the liquid discharge head 3 (strictly speaking, the discharge section D provided by the liquid discharge head 3); A transport mechanism 7 for changing the relative position of the recording paper P with respect to the ink, a storage unit 5 for storing the control program of the ink jet printer 1 and other information, an ink cartridge 40 (see FIG. 2) filled with ink, and ink. Cartridge module including a cartridge control circuit 41 (see FIG. 3) for controlling the operation of the cartridge 40 And an in-head short-circuit detection module 81 (an example of a “detection unit”) for detecting the occurrence of a short circuit in the liquid ejection head 3 and an out-of-head short circuit for detecting the occurrence of a short circuit in a place other than the liquid ejection head 3. A detection module 82 (an example of an “outside head short-circuit detection unit”) and a power supply circuit 9 for supplying power to each unit of the inkjet printer 1 are provided.
In the present embodiment, as illustrated in FIG. 1, the liquid discharge head 3 includes four head units HU, and the drive signal generation module 2 has four drives corresponding to the four head units HU in a one-to-one relationship. Assume that the signal generation circuit 20 is provided.

In the present embodiment, each head unit HU includes a discharge module 30 having M discharge units D, and a drive signal for switching whether to supply the drive signal Com output from the drive signal generation module 2 to the discharge module 30. (In this embodiment, M is a natural number satisfying 1 ≦ M).
Hereinafter, in order to distinguish each of the M ejection portions D provided in each ejection module 30, they may be referred to as “first stage, second stage,..., M stage” in order. In addition, the m stages of ejection portions D may be referred to as ejection portions D [m] (the variable m is a natural number satisfying 1 ≦ m ≦ M). In addition, when the components, signals, etc. of the ink jet printer 1 correspond to the number of stages m of the discharge section D [m], the codes for representing the components, signals, etc. correspond to the number of stages m. May be expressed with a subscript [m].

The in-head short circuit detection module 81 detects whether or not a short circuit has occurred in the head unit HU provided in the liquid ejection head 3. The in-head short circuit detection module 81 outputs a short circuit detection signal XH (strictly, four short circuit detection signals XH) indicating whether or not a short circuit has occurred in the head unit HU.
The out-of-head short circuit detection module 82 detects whether or not a short circuit has occurred in the drive signal generation module 2, the transport mechanism 7, or the cartridge module 4. The out-of-head short circuit detection module 82 outputs a short circuit detection signal XG indicating whether or not a short circuit has occurred in the drive signal generation module 2, the transport mechanism 7, or the cartridge module 4.

  The storage unit 5 includes, for example, a volatile memory such as a RAM (Random Access Memory) and a nonvolatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM). The memory includes one or both of the memory and stores various information such as print data Img supplied from a host computer and a control program for the inkjet printer 1.

The control unit 6 includes a CPU (Central Processing Unit). However, the control unit 6 may include a programmable logic device such as an FPGA (field-programmable gate array) instead of or in addition to the CPU.
The control unit 6 controls each unit of the inkjet printer 1 by executing a control program stored in the storage unit 5 by a CPU provided in the control unit 6. Specifically, the control unit 6 controls the print signal SI for controlling the drive signal supply circuit 31 provided in the liquid ejection head 3 and the drive signal generation circuit 20 provided in the drive signal generation module 2. And a control signal for controlling the transport mechanism 7, a signal for controlling the cartridge module 4, and various control signals such as a signal for controlling the power supply circuit 9.
Here, the waveform designation signal dCom is a digital signal that defines the waveform of the drive signal Com.
The drive signal Com is an analog signal for driving the ejection unit D. The drive signal generation circuit 20 includes a DA conversion circuit, and generates a drive signal Com having a waveform defined by the waveform designation signal dCom. In the present embodiment, it is assumed that the drive signal Com includes the drive signal Com-A and the drive signal Com-B.
The print signal SI is a digital signal for designating the type of operation of the ejection unit D. Specifically, the print signal SI specifies the type of operation of the ejection unit D by designating whether or not to supply the drive signal Com to the ejection unit D. Here, the designation of the type of operation of the ejection part D is, for example, whether or not the ejection part D is to be driven or whether ink is ejected from the ejection part D when the ejection part D is driven. Or specifying the amount of ink ejected from the ejection unit D when the ejection unit D is driven.

  When the printing process is executed, the control unit 6 first stores the print data Img supplied from the host computer in the storage unit 5. Next, based on various data such as print data Img stored in the storage unit 5, the control unit 6 performs various types such as a print signal SI, a waveform designation signal dCom, and a signal for controlling the transport mechanism 7. Generate a control signal. Then, the control unit 6 determines the relative position of the recording paper P with respect to the liquid ejection head 3 based on the print signal SI, the waveform designation signal dCom, various control signals, and various data stored in the storage unit 5. The liquid ejection head 3 is controlled such that the ejection unit D is driven while the transport mechanism 7 is controlled to be changed. Thus, the control unit 6 adjusts the presence / absence of ink ejection from the ejection unit D, the ink ejection amount, the ink ejection timing, and the like, and forms the image corresponding to the print data Img on the recording paper P. Control execution of processing.

FIG. 2 is a partial cross-sectional view illustrating the outline of the internal configuration of the inkjet printer 1. As shown in FIG. 2, in the present embodiment, it is assumed that the ink jet printer 1 includes four ink cartridges 40. Although FIG. 2 illustrates the case where the ink cartridge 40 is provided in the liquid ejection head 3, the ink cartridge 40 may be provided in another location of the inkjet printer 1.
The four ink cartridges 40 are provided in a one-to-one correspondence with four colors (CMYK) of cyan, magenta, yellow, and black. Each ink cartridge 40 includes the ink cartridge 40. Is filled with ink of a corresponding color.

As shown in FIG. 2, the transport mechanism 7 includes a transport motor 70 serving as a drive source for transporting the recording paper P, a motor drive circuit 71 (see FIG. 3) for driving the transport motor 70, and liquid ejection. A platen 74 provided below the head 3 (in the -Z direction in FIG. 2), a transport roller 73 that rotates by the operation of the transport motor 70, and a guide roller 75 that is rotatably provided around the Y axis in FIG. , And a storage unit 76 for storing the recording paper P in a rolled state.
When the inkjet printer 1 executes a printing process, the transport mechanism 7 feeds the recording paper P from the storage unit 76 and follows a transport path defined by the guide roller 75, the platen 74, and the transport roller 73. In the figure, the sheet is conveyed in the + X direction (the direction from the upstream side to the downstream side; hereinafter referred to as “conveying direction Mv”). In the following, as shown in FIG. 2, the + X direction (transport direction Mv) and the opposite −X direction are collectively referred to as the X-axis direction, and the + Z direction (upward direction) and the opposite −Z direction (downward direction). ) Are collectively referred to as the Z-axis direction, and the + Y direction that intersects the X-axis direction and the Z-axis direction and the opposite −Y direction are collectively referred to as the Y-axis direction.

  Each of the 4M ejection portions D provided in the liquid ejection head 3 is supplied with ink from any one of the four ink cartridges 40. Each ejection unit D can fill the ink supplied from the ink cartridge 40 and eject the filled ink from a nozzle N (see FIG. 3) included in the ejection unit D. Specifically, each ejection unit D records dots for constituting an image by ejecting ink onto the recording paper P at a timing when the transport mechanism 7 transports the recording paper P onto the platen 74. Form on paper P. Then, full-color printing is realized by ejecting four CMYK inks as a whole from a total of 4M ejection units D provided in the four head units HU included in the liquid ejection head 3.

<< 2. Power supply for inkjet printers >>
The power supply in the inkjet printer 1 will be described with reference to FIG.

  FIG. 3 is an explanatory diagram for describing an example of a mode of supplying power from the power supply circuit 9 to each unit of the inkjet printer 1.

  As shown in FIG. 3, the power supply circuit 9 includes a terminal Tn1 that outputs a potential VHV and a terminal Tn2 that outputs a potential VBS that is lower than the potential VHV, and a power supply line 901 connected to the terminal Tn1. A predetermined power supply voltage is applied between the power supply line 902 connected to the terminal Tn2. The power supply line 902 is provided with four head units HU provided in the liquid ejection head 3, four drive signal generation circuits 20 provided in the drive signal generation module 2, and the cartridge module 4. The cartridge control circuit 41 and a motor drive circuit 71 provided in the transport mechanism 7 are electrically connected. On the other hand, the power supply line 901 includes a power supply unit 91 (an example of a “head power supply unit”) that supplies power supplied from the power supply circuit 9 via the relay node ND to the four head units HU, and a power supply. A power supply unit 92 (an example of “head external power supply unit”) for supplying power supplied from the circuit 9 via the relay node ND to the drive signal generation module 2, the cartridge control circuit 41, and the motor drive circuit 71. And are electrically connected. Therefore, a predetermined power supply voltage is applied to each head unit HU, each drive signal generation circuit 20, the cartridge control circuit 41, and the motor drive circuit 71 (that is, power is supplied). Hereinafter, the four drive signal generation circuits 20, the cartridge control circuit 41, and the motor drive circuit 71 are referred to as a processing circuit 100.

  As shown in FIG. 3, the power supply unit 91 includes four power supply lines 911 and four fuses provided in a one-to-one correspondence with the four head units HU included in the liquid discharge head 3. 912. Specifically, the power supply unit 91 includes a power supply line 911 that is electrically connected to the head unit HU, and a fuse 912 that is electrically connected between the power supply line 911 and the relay node ND. For this reason, when a short circuit occurs in the head unit HU, the fuse 912 is cut, and it is possible to prevent an overcurrent from continuing to flow to the head unit HU.

  As shown in FIG. 3, the power supply unit 92 includes a power supply line 921 that is electrically connected to the processing circuit 100, and a fuse 922 that is electrically connected between the power supply line 921 and the relay node ND. For this reason, when a short circuit occurs in the processing circuit 100, the fuse 922 is cut, and it is possible to prevent an overcurrent from continuing to flow through the processing circuit 100.

As shown in FIG. 3, the in-head short-circuit detection module 81 includes four detection circuits 810 provided to correspond to the four head units HU in a one-to-one correspondence. Each detection circuit 810 detects the potential of the power supply line 911 electrically connected to the head unit HU corresponding to the detection circuit 810, and outputs a short circuit detection signal XH based on the detection result.
Specifically, the detection circuit 810 sets the signal level of the short circuit detection signal XH to a predetermined signal level when the potential difference between the potential of the power supply line 911 and the potential VHV is larger than a predetermined value. For example, the detection circuit 810 sets the short-circuit detection signal XH to a high level when the potential difference between the potential of the power supply line 911 and the potential VHV is equal to or less than a predetermined value, and the potential difference between the potential of the power supply line 911 and the potential VHV is When it is larger than the predetermined value, the short circuit detection signal XH may be set to a low level.
For this reason, the detection circuit 810 generates a predetermined signal when a short circuit occurs in the head unit HU provided corresponding to the detection circuit 810 and the fuse 912 provided corresponding to the head unit HU is cut. The short circuit detection signal XH set to the signal level (for example, low level) is output. Thereby, the control part 6 can grasp | ascertain whether the short circuit has generate | occur | produced in each head unit HU based on the signal level of the short circuit detection signal XH.

As shown in FIG. 3, the out-of-head short circuit detection module 82 includes a detection circuit 820 that detects the potential of the power supply line 921. The detection circuit 820 outputs a short circuit detection signal XG based on the detection result. Specifically, the detection circuit 820 sets the signal level of the short circuit detection signal XG to a predetermined signal level when the potential difference between the potential of the power supply line 921 and the potential VHV is larger than a predetermined value. For example, the detection circuit 820 sets the short-circuit detection signal XG to a high level when the potential difference between the potential of the power supply line 921 and the potential VHV is equal to or less than a predetermined value, and the potential difference between the potential of the power supply line 921 and the potential VHV is When it is larger than the predetermined value, the short circuit detection signal XG is set to a low level.
Therefore, the detection circuit 820 outputs a short circuit detection signal XG set to a predetermined signal level (for example, low level) when a short circuit occurs in the processing circuit 100 and the fuse 922 is cut. Thereby, the control part 6 can grasp | ascertain whether the short circuit has generate | occur | produced in the processing circuit 100 based on the signal level of the short circuit detection signal XG. In other words, the control unit 6 grasps whether or not a short circuit has occurred in the drive signal generation circuit 20, the cartridge control circuit 41, or the motor drive circuit 71 based on the signal level of the short circuit detection signal XG. Can do.

<< 3. Outline of discharge module and discharge section >>
The discharge module 30 and the discharge part D provided in the discharge module 30 will be described with reference to FIGS. 4 and 5.

FIG. 4 is a schematic partial cross-sectional view of the discharge module 30 in which the discharge module 30 is cut so as to include the discharge portion D.
As shown in FIG. 4, the ejection unit D includes a piezoelectric element PZ, a cavity 320 filled with ink, a nozzle N communicating with the cavity 320, and a vibration plate 310.
The cavity 320 is a space defined by the cavity plate 340, the nozzle plate 330 in which the nozzles N are formed, and the vibration plate 310. The cavity 320 communicates with the reservoir 350 via the ink supply port 360. The reservoir 350 communicates with the ink cartridge 40 corresponding to the ejection unit D via the ink intake port 370.
The piezoelectric element PZ includes an upper electrode Zu, a lower electrode Zd, and a piezoelectric body Zm provided between the upper electrode Zu and the lower electrode Zd. The lower electrode Zd is electrically connected to the power supply line 902 set at the potential VBS, and a drive signal Com is supplied to the upper electrode Zu, whereby a voltage is applied between the upper electrode Zu and the lower electrode Zd. Then, the piezoelectric element PZ is displaced in the + Z direction or the −Z direction according to the applied voltage. In this embodiment, a unimorph (monomorph) type as shown in FIG. 3 is adopted as the piezoelectric element PZ. The piezoelectric element PZ is not limited to a unimorph type, but may be a bimorph type or a laminated type.
A diaphragm 310 is installed in the upper surface opening of the cavity plate 340. A lower electrode Zd is joined to the vibration plate 310. For this reason, when the piezoelectric element PZ is driven and displaced by the drive signal Com, the diaphragm 310 is also displaced. Then, the volume of the cavity 320 changes due to the displacement of the vibration plate 310, and the ink filled in the cavity 320 is ejected from the nozzle N. Ink is supplied from the reservoir 350 when the ink in the cavity 320 decreases due to ink ejection.

FIG. 5 shows four ejection modules 30 provided in the liquid ejection head 3 and a total of 4M nozzles N provided in the four ejection modules 30 when the inkjet printer 1 is viewed in plan from the + Z direction. It is explanatory drawing for demonstrating an example of arrangement | positioning.
As shown in FIG. 5, each ejection module 30 provided in the liquid ejection head 3 is provided with a nozzle row Ln. Here, the nozzle row Ln is a plurality of nozzles N provided so as to extend in a row in a predetermined direction. In the present embodiment, as an example, in each ejection module 30, four nozzle rows Ln including a nozzle row Ln-BK, a nozzle row Ln-CY, a nozzle row Ln-MG, and a nozzle row Ln-YL. Assuming that is provided. The nozzles N belonging to the nozzle row Ln-BK are nozzles N provided in the discharge unit D that discharges black ink, and the nozzles N belonging to the nozzle row Ln-CY are discharge units that discharge cyan ink. Nozzle N provided in D, and nozzle N belonging to nozzle row Ln-MG is nozzle N provided in ejection unit D that ejects magenta ink, and nozzle N belonging to nozzle row Ln-YL is This is a nozzle N provided in the discharge section D that discharges yellow ink. In the present embodiment, as an example, a case is assumed in which each of the four nozzle rows Ln is provided to extend in the Y-axis direction when viewed in plan in each discharge module 30.

  As shown in FIG. 5, the liquid ejection head 3 according to the present embodiment is a so-called line head. That is, the liquid ejection head 3 causes the ink jet printer 1 to perform print processing on the recording paper P (more precisely, the recording paper P whose width in the Y-axis direction has the maximum printable width of the ink jet printer 1). In this case, the extending range YNL in the Y-axis direction of the total 4M nozzles N included in the liquid discharge head 3 includes the range YP in the Y-axis direction of the recording paper P.

  In the present embodiment, the range YP is a range having a width of 297 mm or more. That is, the line head (liquid ejection head 3) included in the ink jet printer 1 according to the present embodiment has a size capable of printing on the recording paper P in the A4 size. In the present embodiment, it is assumed that the nozzles N are arranged in the liquid ejection head 3 so that printing can be performed with a dot density of 600 dpi or more.

The arrangement of the four ejection modules 30 in the liquid ejection head 3 and the arrangement of the nozzle rows Ln in each ejection module 30 shown in FIG. 5 are merely examples. In each liquid discharge head 3, the discharge module 30 and each nozzle row Ln may be arranged in any way.
For example, in FIG. 5, the nozzle row Ln is provided so as to extend in the Y-axis direction, but the nozzle row Ln may be provided as long as it extends in an arbitrary direction within the XY plane. The nozzle row Ln may be provided so as to extend in a direction different from the Y-axis direction and the X-axis direction, for example, an oblique direction in the drawing.
In FIG. 5, four nozzle rows Ln are provided in each discharge module 30, but one or more nozzle rows Ln may be provided in each discharge module 30.
In FIG. 5, a plurality of nozzles N constituting each nozzle row Ln are provided so as to be arranged in a line in the Y-axis direction. In FIG. 5, even-numbered nozzles N and odd-numbered nozzles N It may be arranged in a so-called staggered manner so that the positions in the X-axis direction are different from each other.

<< 4. Head unit configuration >>
Hereinafter, the configuration of each head unit HU will be described with reference to FIG.

  FIG. 6 is a block diagram showing an example of the configuration of the head unit HU. As described above, the head unit HU includes the ejection module 30 and the drive signal supply circuit 31. The head unit HU includes an internal wiring LHa to which the drive signal Com-A is supplied from the drive signal generation module 2 and an internal wiring LHb to which the drive signal Com-B is supplied from the drive signal generation module 2. In addition, a power supply line 902 set at the potential VBS is connected to the head unit HU.

As shown in FIG. 6, the drive signal supply circuit 31 includes M switches SWa (SWa [1] to SWa [M]), M switches SWb (SWb [1] to SWb [M]), A connection state designating circuit 32 for designating the connection state of each switch. As each switch, for example, a transmission gate can be adopted.
The connection state designation circuit 32 designates ON / OFF of the switches SWa [1] to SWa [M] based on the print signal SI, the latch signal LAT, and the change signal CNG supplied from the control unit 6. SLa [1] to SLa [M] and connection state designation signals SLb [1] to SLb [M] for designating on / off of the switches SWb [1] to SWb [M] are generated.
The switch SWa [m] is connected between the internal wiring LHa and the upper electrode Zu [m] of the piezoelectric element PZ [m] provided in the ejection part D [m] in response to the connection state designation signal SLa [m]. Switch between conduction and non-conduction. In the present embodiment, as an example, it is assumed that the switch SWa [m] is turned on when the connection state designation signal SLa [m] is at a high level and turned off when the connection state designation signal SLa [m] is at a low level.
The switch SWb [m] is connected between the internal wiring LHb and the upper electrode Zu [m] of the piezoelectric element PZ [m] provided in the ejection part D [m] in response to the connection state designation signal SLb [m]. Switch between conduction and non-conduction. In the present embodiment, as an example, it is assumed that the switch SWb [m] is turned on when the connection state designation signal SLb [m] is at a high level and turned off when the connection state designation signal SLb [m] is at a low level.
Of the drive signals Com-A and Com-B, a signal actually supplied to the piezoelectric element PZ [m] of the discharge section D [m] via the switch SWa [m] or SWb [m] It may be referred to as a supply drive signal Vin [m].

<< 5. Head unit operation >>
Hereinafter, the operation of each head unit HU will be described with reference to FIGS.

  In the present embodiment, the operation period of the inkjet printer 1 includes one or a plurality of unit periods Tu. The ink jet printer 1 can execute a printing process in each unit period Tu. Strictly speaking, the ink jet printer 1 can execute a process of driving each ejection unit D and ejecting ink from each ejection unit D among the printing processes in each unit period Tu. For example, the inkjet printer 1 repeatedly executes the printing process over a plurality of continuous or intermittent unit periods Tu, and ejects ink from each ejection unit D one or more times, thereby printing data Img. Is formed.

FIG. 7 is a timing chart for explaining an example of the operation of the inkjet printer 1 in the unit period Tu.
As shown in FIG. 7, the control unit 6 outputs a latch signal LAT having a pulse PlsL and a change signal CNG having a pulse PlsC. Thereby, the control unit 6 defines the unit period Tu as a period from the rising of the pulse PlsL to the rising of the next pulse PlsL. Further, the control unit 6 divides the unit period Tu into two control periods Ts1 and Ts2 by the pulse PlsC.
The print signal SI includes individual designation signals Sd [1] to Sd [M] that designate the driving mode of the ejection units D [1] to D [M] in each unit period Tu. When the printing process is executed in the unit period Tu, the control unit 6 includes individual designation signals Sd [1] to Sd [M] prior to the start of the unit period Tu as shown in FIG. The print signal SI is supplied to the connection state designating circuit 32 in synchronization with the clock signal CLK. In this case, the connection state designation circuit 32 generates connection state designation signals SLa [m] and SLb [m] based on the individual designation signal Sd [m] in the unit period Tu.

As shown in FIG. 7, the drive signal generation circuit 20 outputs a drive signal Com-A having a waveform PX provided in the control period Ts1 and a waveform PY provided in the control period Ts2. In the present embodiment, the waveform PX and the waveform PY are determined so that the potential difference between the highest potential VHX and the lowest potential VLX of the waveform PX is larger than the potential difference between the highest potential VHY and the lowest potential VLY of the waveform PY. Specifically, when the ejection portion D [m] is driven by the drive signal Com-A having the waveform PX, an amount of ink corresponding to a medium dot (medium amount) is ejected from the ejection portion D [m]. Thus, the waveform of the waveform PX is determined. Further, when the ejection unit D [m] is driven by the drive signal Com-A having the waveform PY, an amount of ink corresponding to a small dot (a small amount) is ejected from the ejection unit D [m]. The waveform PY is determined. In the waveforms PX and PY, the potential at the start and end is set to the reference potential V0.
The drive signal generation circuit 20 outputs a drive signal Com-B having two waveforms PB provided in each of the control periods Ts1 and Ts2. In the present embodiment, the waveform PB is determined so that the potential difference between the highest potential VHB and the lowest potential VLB of the waveform PB is smaller than the potential difference between the highest potential VHY and the lowest potential VLY of the waveform PY. Specifically, when the ejection unit D [m] is driven by the drive signal Com-B having the waveform PB, the ejection unit D [m] is driven to the extent that no ink is ejected from the ejection unit D [m]. Next, the waveform PB is determined. In the waveform PB, the potential at the start and end is set to the reference potential V0. In the present embodiment, the highest potential VHB is the reference potential V0.

FIG. 8 is an explanatory diagram for explaining an example of the relationship between the individual designation signal Sd [m] and the connection state designation signals SLa [m] and SLb [m] in the unit period Tu.
As shown in FIG. 8, in the present embodiment, it is assumed that the individual designation signal Sd [m] is a 2-bit digital signal. Specifically, the individual designation signal Sd [m] discharges an amount of ink corresponding to a large dot (a large amount) (“large dot”) to the discharge unit D [m] in each unit period Tu. A value (1, 1) designating a medium amount of ink (which may be referred to as “medium dot formation”) (1, 0) A value (0, 1) that designates ejection of a small amount of ink (sometimes referred to as “small dot formation”) and a value (0, 0) that designates non-ejection of ink. One of the values is set.

When the individual designation signal Sd [m] is set to a value (1, 1) designating the formation of a large dot, the connection state designation circuit 32 sends the connection state designation signal SLa [m] to the control period Ts1 and The high level is set at Ts2, and the connection state designation signal SLb [m] is set to the low level during the control periods Ts1 and Ts2. In this case, the ejection unit D [m] is driven by the drive signal Com-A having the waveform PX in the control period Ts1 and ejects a medium amount of ink, and the drive signal Com− having the waveform PY in the control period Ts2. Driven by A, a small amount of ink is ejected. Accordingly, the ejection unit D [m] ejects a large amount of ink in total in the unit period Tu, and a large dot is formed on the recording paper P.
When the individual designation signal Sd [m] is set to a value (1,0) designating the formation of medium dots, the connection status designation circuit 32 sends the connection status designation signal SLa [m] in the control period Ts1. The connection state designation signal SLb [m] is set to a low level in the control period Ts2 and set to a low level in the control period Ts2. In this case, the ejection part D [m] ejects a medium amount of ink in the unit period Tu, and medium dots are formed on the recording paper P.
When the individual designation signal Sd [m] is set to a value (0, 1) designating the formation of small dots, the connection state designation circuit 32 sends the connection state designation signal SLa [m] in the control period Ts1. The low level is set to the high level in the control period Ts2, and the connection state designation signal SLb [m] is set to the high level in the control period Ts1 and the low level in the control period Ts2. In this case, the ejection unit D [m] ejects a small amount of ink in the unit period Tu, and small dots are formed on the recording paper P.
When the individual designation signal Sd [m] is set to a value (0, 0) that designates non-ejection of ink, the connection state designation circuit 32 sends the connection state designation signal SLa [m] to the control periods Ts1 and Ts2. The connection state designation signal SLb [m] is set to the high level in the control periods Ts1 and Ts2. In this case, the ejection unit D [m] does not eject ink and does not form dots on the recording paper P in the unit period Tu.

FIG. 9 is a diagram illustrating an example of the configuration of the connection state designating circuit 32 according to the present embodiment. As shown in FIG. 9, the connection state designation circuit 32 generates connection state designation signals SLa [1] to SLa [M] and connection state designation signals SLb [1] to SLb [M].
Specifically, the connection state designating circuit 32 includes transfer circuits SR [1] to SR [M] and a latch circuit LT [M] so as to correspond one-to-one with the discharge units D [1] to D [M]. 1] to LT [M] and decoders DC [1] to DC [M]. Among these, the individual designation signal Sd [m] is supplied to the transfer circuit SR [m]. In this figure, the individual designation signals Sd [1] to Sd [M] are supplied serially. For example, the individual designation signal Sd [m] corresponding to m stages is transferred from the transfer circuit SR [1] to the transfer circuit SR. A case is illustrated in which [m] is sequentially transferred in synchronization with the clock signal CLK. The latch circuit LT [m] latches the individual designation signal Sd [m] supplied to the transfer circuit SR [m] at the timing when the pulse PlsL of the latch signal LAT rises to a high level. Further, the decoder DC [m] generates connection state designation signals SLa [m] and SLb [m] according to FIG. 8 based on the individual designation signal Sd [m], the latch signal LAT, and the change signal CH. .

<< 6. Conclusion of embodiment >>
Hereinafter, in order to clarify the effect of the present embodiment, a power supply aspect related to the proportionality will be described.

FIG. 10 is an explanatory diagram for explaining a power supply mode in the inkjet printer 1T according to the comparative example.
As shown in FIG. 10, in the proportional inkjet printer 1T, the power supply circuit 9 outputs the potential VHV from the terminal Tn1 of the power supply circuit 9 to the power supply line 901 electrically connected to the terminal Tn1. A predetermined power supply voltage is applied between the power supply line 901 and the power supply line 902 by outputting the potential VBS from the terminal Tn2 of the circuit 9 to the power supply line 902 electrically connected to the terminal Tn2. In the inkjet printer 1T, the four head units HU and the processing circuit 100 are electrically connected to the power supply line 902, and the four power units HU and the processing circuit 100 are supplied with power to the power supply line 901. A power feeding unit 91T for electrical connection is electrically connected. The power supply unit 91T includes a power supply line 911T electrically connected to the four head units HU and the processing circuit 100, and a fuse 912T electrically connected between the power supply line 911T and the power supply line 901. And a detection circuit 810T that detects a potential of the electric wire 911T and outputs a short-circuit detection signal XH representing the detection result. Therefore, when the short circuit occurs in the four head units HU or the processing circuit 100 and the fuse 912T is cut, the control unit 6 detects the short circuit detection signal XH set to a predetermined signal level output from the detection circuit 810T. Based on the above, it is possible to grasp that a short circuit has occurred in any of the four head units HU and the processing circuit 100.

  However, in the comparative inkjet printer 1T as shown in FIG. 10, the control unit 6 causes a short circuit to occur in any of the four head units HU and the processing circuit 100 based on the short circuit detection signal XH. It is difficult to identify the location where the short-circuit occurs, although it is possible to grasp the situation. In other words, in the inkjet printer 1T according to the proportionality, when a short circuit occurs in the head unit HU, it is difficult to quickly identify that the location of the short circuit is the head unit HU.

  On the other hand, according to the present embodiment, four fuses 912 and four detection circuits 810 are provided so as to correspond to the four head units HU on a one-to-one basis. For this reason, according to the present embodiment, when a short circuit occurs in one head unit HU, it is possible to quickly identify that the short-circuit occurrence point is the one head unit HU. Thereby, according to this embodiment, the maintainability of the inkjet printer 1 can be improved.

  In the present embodiment, of the four head units HU provided in the liquid ejection head 3, one head unit HU is an example of a “first head unit”, and the other head unit HU is “second”. It is an example of a “head unit”. In the present embodiment, the power supply line 911 electrically connected to one head unit HU is an example of a “first power supply line”, and the fuse 912 provided corresponding to one head unit HU is “ The power supply line 911 that is an example of the “first fuse” and is electrically connected to the other head unit HU is an example of the “second power supply line”, and the fuse 912 provided corresponding to the other head unit HU. Is an example of a “second fuse”. In the present embodiment, the power supply line 921 electrically connected to the processing circuit 100 is an example of a “third power supply line”, and the fuse 922 electrically connected between the power supply line 921 and the relay node ND. Is an example of a “third fuse”.

<< B. Modification >>
Each of the above forms can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined within a range that does not contradict each other. In addition, about the element which an effect | action and a function are equivalent to embodiment in the modification illustrated below, the code | symbol referred by the above description is diverted and each detailed description is abbreviate | omitted suitably.

<< Modification 1 >>
In the embodiment described above, the in-head short-circuit detection module 81 is provided with the four detection circuits 810 so as to correspond to the four head units HU, but the present invention is limited to such a mode. However, the in-head short circuit detection module 81 only needs to include one or more detection circuits 810.
In the above-described embodiment, the power supply unit 91 is provided with the four fuses 912 so as to correspond to the four head units HU, but the present invention is limited to such an embodiment. Instead, the power supply unit 91 only needs to include one or more fuses 912.
For example, as shown in FIG. 11, the power supply unit 91 includes a power supply line 911A electrically connected to the four head units HU, and a fuse 912 electrically connected between the power supply line 911A and the relay node ND. The in-head short circuit detection module 81 may include a single detection circuit 810 that detects the potential of the power supply line 911A. Even in this case, when a short circuit occurs in any one of the four head units HU, it is quickly identified that the short-circuit occurrence point is any one of these four head units HU. be able to.

<< Modification 2 >>
In the embodiment and the modification described above, the processing circuit 100 includes the four drive signal generation circuits 20 provided in the drive signal generation module 2, the cartridge control circuit 41 provided in the cartridge module 4, and the transport mechanism 7. However, the present invention is not limited to such an embodiment, and the processing circuit 100 is a component provided at a place other than the liquid ejection head 3. And what is necessary is just to include the one part or all of the component which operate | moves with the electric power supplied from the power supply circuit 9. FIG.

<< Modification 3 >>
In the embodiment and the modification described above, the power feeding unit 92 includes one fuse 922. However, the present invention is not limited to such a mode, and the power feeding unit 92 includes two or more fuses 922. May be. For example, the power supply unit 92 may include a plurality of fuses 922 that correspond one-to-one with a plurality of components included in the processing circuit 100. In this case, the power supply unit 92 preferably includes a plurality of power supply lines 921 that correspond one-to-one with a plurality of components included in the processing circuit 100. Specifically, in this modification, the power supply unit 92 is electrically connected between each component included in the processing circuit 100 and a fuse 922 provided corresponding to the component. It is preferable to provide a plurality of power supply lines 921 corresponding to a plurality of components one to one.
In the embodiment and the modification described above, the outside-head short-circuit detection module 82 includes one detection circuit 820. However, the present invention is not limited to such a mode. Two or more detection circuits 820 may be provided. For example, the power supply unit 92 includes a plurality of power supply lines 921 that correspond one-to-one with a plurality of components included in the processing circuit 100, and a plurality of components that correspond one-to-one with a plurality of components included in the processing circuit 100. When the fuse 922 is provided, the external head short circuit detection module 82 preferably includes a plurality of detection circuits 820 corresponding to the plurality of power supply lines 921 one-to-one. In this case, the out-of-head short circuit detection module 82 can quickly identify the component in which the short circuit has occurred when a short circuit occurs in any of the plurality of components included in the processing circuit 100.

<< Modification 4 >>
In the embodiment and the modification described above, the range YP is 297 mm or more, and a plurality of nozzles N are arranged in the liquid discharge head 3 so as to extend to the range YNL of 297 mm or more. Is not limited to such an embodiment, and the range YP may be less than 297 mm. In this case, a plurality of nozzles N may be arranged in the liquid ejection head 3 so as to extend in a range including the range YP.

  In the above-described embodiments and modifications, the nozzles N are arranged in the liquid ejection head 3 so that printing can be performed with a dot density of 600 dpi or more. However, the present invention is limited to such an embodiment. The nozzles N may be arranged in the liquid discharge head 3 so that only printing with a dot density of less than 600 dpi is possible. However, it is preferable that nozzles N (discharge portions D) are arranged in the liquid discharge head 3 at a density of 300 or more per inch.

<< Modification 5 >>
In the embodiment and the modification described above, the liquid discharge head 3 includes four head units HU. However, the present invention is not limited to such an aspect, and the liquid discharge head 3 includes one or more head units. What is necessary is just to have HU.
Further, in the above-described embodiments and modifications, the drive signal generation module 2 is provided with the drive signal generation circuit 20 in one-to-one correspondence with the head unit HU, but the present invention is limited to such an aspect. Instead, the drive signal generation module 2 may be provided with two or more drive signal generation circuits 20 for one head unit HU, or for two or more head units HU. One drive signal generation circuit 20 may be provided.

<< Modification 6 >>
In the above-described embodiments and modifications, it is assumed that the inkjet printer 1 is a line printer. However, the present invention is not limited to such a mode, and the inkjet printer 1 has a liquid ejection head 3 with a Y axis. It may be a so-called serial printer that executes the printing process while moving in the direction.

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 2 ... Drive signal generation module, 3 ... Liquid discharge head, 4 ... Cartridge module, 5 ... Memory | storage part, 6 ... Control part, 7 ... Conveyance mechanism, 9 ... Power supply circuit, 20 ... Drive signal generation circuit, DESCRIPTION OF SYMBOLS 30 ... Discharge module, 31 ... Drive signal supply circuit, 41 ... Cartridge control circuit, 71 ... Motor drive circuit, 81 ... In-head short circuit detection module, 82 ... Outside head short circuit detection module, 91 ... Power supply part, 92 ... Power supply part, DESCRIPTION OF SYMBOLS 100 ... Processing circuit, 810 ... Detection circuit, 820 ... Detection circuit, 911 ... Feed line, 912 ... Fuse, 921 ... Feed line, 922 ... Fuse, D ... Discharge part, HU ... Head unit.

Claims (5)

A liquid ejection head provided with a first head unit having a plurality of ejection units for ejecting liquid;
A processing circuit provided at a different location from the liquid ejection head;
A power supply circuit for supplying power;
A relay node electrically connected to the power supply circuit;
A head feeding unit for transmitting power supplied from the power supply circuit via the relay node to the first head unit;
An external power feeding unit for transmitting the power supplied from the power supply circuit via the relay node to the processing circuit;
A detection unit capable of detecting occurrence of a short circuit in the first head unit;
With
The head power feeding unit is
A first feeder line electrically connected to the first head unit;
A first fuse electrically connected between the first feeder and the relay node;
Comprising
The detector is
Detecting the occurrence of a short circuit in the first head unit based on the potential of the first feeder line;
A liquid discharge apparatus characterized by that. The first head unit is
Comprising at least 300 of the discharge units per inch;
The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The liquid discharge head is
A second head unit having a plurality of ejection units for ejecting liquid;
The head power feeding unit is
A second feeder line electrically connected to the second head unit;
A second fuse electrically connected between the second feeder and the relay node;
Comprising
The detector is
Detecting the occurrence of a short circuit in the second head unit based on the potential of the second feeder line;
The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. The liquid discharge head is
A second head unit having a plurality of ejection units for ejecting liquid;
The head power feeding unit is
A second feeder line electrically connected to the second head unit;
The first fuse is
Electrically connected between the second feeder and the relay node;
The detector is
Based on at least one of the potential of the first feed line or the potential of the second feed line,
Detecting occurrence of a short circuit in at least one of the first head unit and the second head unit;
The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is a liquid ejecting apparatus. An outside-head short-circuit detecting unit capable of detecting the occurrence of a short circuit in the processing circuit;
The head external power supply unit is
A third feeder line electrically connected to the processing circuit;
A third fuse electrically connected between the third feeder and the relay node;
Comprising
The outside-head short-circuit detecting unit is
Detecting the occurrence of a short circuit in the processing circuit based on the potential of the third feeder line;
The liquid ejection apparatus according to claim 1, wherein the liquid ejection apparatus is a liquid ejection apparatus according to claim 1.

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