Liquid ejection head control circuit and liquid ejection device

Abstract

To provide a liquid discharge head control circuit capable of reducing a risk of an occurrence of malfunction in a liquid discharge device.SOLUTION: A liquid discharge head control circuit for controlling a liquid discharge head having a drive element and a switching circuit for switching whether or not to supply a drive signal to the drive element includes a drive signal output circuit for outputting a drive signal and a switching control circuit for controlling the switching circuit. The switching control circuit outputs a discharge control signal for stipulating an amount of liquid discharged from a nozzle, a switching timing signal for stipulating a switching timing of the switching circuit, and a state selection signal for stipulating a state of the switching circuit in a control period stipulated by the switching timing signal. The state selection signal in a first period for controlling the liquid discharge head so that liquid is discharged from the nozzle is different from the state selection signal in a second period for controlling the liquid discharge head so that liquid is not discharged from the nozzle.SELECTED DRAWING: Figure 16

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head control circuit and a liquid ejection apparatus. [Background technology]

[0002] Known liquid ejection devices, such as inkjet printers, are of the so-called piezoelectric type, which form characters or images on a medium by driving a drive element including a piezoelectric element provided in a liquid ejection head using a drive signal, and ejecting liquid such as ink filled in a cavity from a nozzle by driving the drive element.

[0003] Such liquid ejection devices are known to have a configuration in which information defining the amount of liquid ejected from the liquid ejection head is output from a liquid ejection head control circuit that controls the driving of the liquid ejection head, thereby enabling settings and changes to be made according to the characteristics of the liquid ejection head to be used and the ink ejected from the liquid ejection head.For example, Patent Document 1 discloses an inkjet printer that makes it possible to control the ejection amount for each ink color within a printing cycle by transmitting an ejection pattern ejected from the nozzles from a printer controller (liquid ejection head control circuit) to a print head (liquid ejection head).

[0004] Patent document 2 also discloses a liquid ejection device in which the liquid ejection head has a diagnostic circuit that diagnoses the condition of the liquid ejection head, and the liquid ejection head performs self-diagnosis based on a latch signal LAT, a change signal CHa, a clock signal SCK, and a print data signal SI that are input to the diagnostic circuit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-001824 A [Patent Document 2] JP 2020-104507 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, when a liquid ejection head control circuit that causes the liquid ejection head to perform control other than liquid ejection, such as the self-diagnosis described in Patent Document 2, and a liquid ejection device are equipped with a function that controls the ejection pattern ejected from the nozzle by transmitting the ejection pattern ejected from the nozzle from the liquid ejection head control circuit to the liquid ejection head, as described in Patent Document 1, there is a risk of the liquid ejection device malfunctioning because the signal for performing control other than liquid ejection and the signal for defining the ejection pattern ejected from the nozzle are the same signal. [Means for solving the problem]

[0007] One aspect of the liquid ejection head control circuit according to the present invention is A liquid ejection head control circuit for controlling a liquid ejection head having a drive element that is driven based on a drive signal to eject liquid from a nozzle, and a switching circuit that switches whether or not the drive signal is supplied to the drive element, A drive signal output circuit that outputs the drive signal; A switching control circuit for controlling the switching circuit; Equipped with The switching control circuit includes: a discharge control signal that defines the amount of liquid discharged from the nozzle; A switching timing signal that defines a switching timing of the switching circuit; a state selection signal that defines a state of the switching circuit during a control period defined by the switching timing signal; and The state selection signal in a first period for controlling the liquid ejection head so that liquid is ejected from the nozzle is different from the state selection signal in a second period for controlling the liquid ejection head so that liquid is not ejected from the nozzle.

[0008] One aspect of the liquid ejection device according to the present invention is to a liquid ejection head including a drive element that is driven based on a drive signal to eject liquid from a nozzle, and a switching circuit that switches whether or not the drive signal is supplied to the drive element; a liquid ejection head control circuit for controlling the liquid ejection head; Equipped with The liquid ejection head control circuit includes: A drive signal output circuit that outputs the drive signal; A switching control circuit for controlling the switching circuit; Equipped with The switching control circuit includes: a discharge control signal that defines the amount of liquid discharged from the nozzle; A switching timing signal that defines a switching timing of the switching circuit; a state selection signal that defines a state of the switching circuit during a control period defined by the switching timing signal; and The state selection signal in a first period for controlling the liquid ejection head so that liquid is ejected from the nozzle is different from the state selection signal in a second period for controlling the liquid ejection head so that liquid is not ejected from the nozzle. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a liquid ejection device. [Diagram 2] FIG. 2 is a diagram illustrating a functional configuration of the liquid ejection device. [Diagram 3] FIG. 2 is a diagram for explaining a schematic configuration of a discharge unit. [Figure 4] FIG. 4 is a diagram showing a configuration of a drive signal selection circuit. [Diagram 5] FIG. 4 is a diagram showing an electrical configuration of a selection control circuit. [Figure 6] 5A to 5C are diagrams for explaining a latch signal, a change signal, a clock signal, and a head control signal. [Figure 7] 5 is a diagram showing an example of a data configuration of a head control signal. FIG. [Figure 8] FIG. 13 is a diagram showing the decoded contents of a decoder. [Figure 9] FIG. 4 is a diagram showing the configuration of a selection circuit corresponding to one of the ejection parts. [Figure 10] 4 is a diagram showing an example of the waveforms of drive signals COMA and COMB. FIG. [Figure 11] 11 is a diagram showing an example of a head control signal DI output by the control mechanism 10 during an ejection control period. FIG. [Figure 12] 13 is a diagram showing the decoded contents in a decoder of the selection control circuit 210a during the discharge control period. FIG. [Figure 13] FIG. 13 is a diagram showing the decoded contents in a decoder of the selection control circuit 210b during the discharge control period. [Figure 14] 14 is a diagram for explaining the operation of the selection circuit when selection signals Sa and Sb shown in FIGS. 12 and 13 are supplied. FIG. [Figure 15] 11A and 11B are diagrams illustrating an example of an operation performed when a control mechanism acquires information stored in a memory circuit. [Figure 16] 11 is a diagram showing an example of head control signals DIA, DIB output by a control mechanism during a non-ejection control period. FIG. [Figure 17] 13 is a diagram showing the decoded contents in a decoder 226 of a selection control circuit 210a during a non-ejection control period. FIG. [Figure 18] 13 is a diagram showing the decoded contents in the decoder 226 of the selection control circuit 210b during the non-ejection control period. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Preferred embodiments of the present invention will be described below with reference to the drawings. The drawings are used for the convenience of explanation. Note that the embodiments described below do not unduly limit the contents of the present invention described in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0011] 1. Overview of the liquid ejection device FIG. 1 is a diagram showing a schematic configuration of a liquid ejection device 1. The liquid ejection device 1 in this embodiment is an inkjet printer of a serial printing type in which a carriage 20 mounted with a liquid ejection head 21 that ejects ink as an example of liquid moves back and forth to eject ink onto a medium P being transported, thereby forming an image on the medium P. In the following description, the direction in which the carriage 20 moves is the X direction, the direction in which the medium P is transported is the Y direction, and the direction in which the ink is ejected is the Z direction. Note that the X direction, the Y direction, and the Z direction are described as directions perpendicular to each other, but the various components constituting the liquid ejection device 1 are not limited to being arranged perpendicular to each other. In addition, any printing target such as printing paper, a resin film, or a fabric can be used as the medium P. Note that the liquid ejection device 1 may be an inkjet printer of a so-called line printing type in which the liquid ejection heads 21 are arranged in a row so as to form a nozzle row greater than the width of the medium, and a desired image is formed on the medium by ejecting ink from the liquid ejection heads 21 onto the medium being transported.

[0012] As shown in FIG. 1, the liquid ejection device 1 includes an ink container 2, a control mechanism 10, a carriage 20, a moving mechanism 30, and a transport mechanism 40.

[0013] The ink container 2 stores multiple types of ink to be ejected onto the medium P. Colors of ink stored in the ink container 2 include black, cyan, magenta, yellow, red, gray, etc. As the ink container 2 in which such ink is stored, an ink cartridge, a bag-shaped ink pack formed of a flexible film, an ink tank that can be refilled with ink, etc. can be used.

[0014] The control mechanism 10 includes a processing circuit such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and controls each element of the liquid ejection device 1 including the liquid ejection head 21.

[0015] A liquid ejection head 21 is mounted on the carriage 20. The carriage 20 is fixed to an endless belt 32 included in a moving mechanism 30. The ink container 2 may be mounted on the carriage 20.

[0016] A control signal Ctrl-H for controlling the liquid ejection head 21, which is output by the control mechanism 10, and one or more drive signals COM for driving the liquid ejection head 21 are input to the liquid ejection head 21. The liquid ejection head 21 ejects ink supplied from the ink container 2, based on the input control signal Ctrl-H and drive signal COM.

[0017] The moving mechanism 30 includes a carriage motor 31 and an endless belt 32. The carriage motor 31 operates based on a control signal Ctrl-C input from the control mechanism 10. The endless belt 32 rotates in accordance with the operation of the carriage motor 31. This causes the carriage 20 fixed to the endless belt 32 to reciprocate in the X direction.

[0018] The transport mechanism 40 includes a transport motor 41 and a transport roller 42. The transport motor 41 operates based on a control signal Ctrl-T input from the control mechanism 10. The transport roller 42 rotates in accordance with the operation of the transport motor 41. The medium P is transported in the Y direction in accordance with the rotation of the transport roller 42.

[0019] As described above, the liquid ejection device 1 ejects ink along the Z direction from the liquid ejection head 21 mounted on the carriage 20 in conjunction with the transport of the medium P by the transport mechanism 40 and the reciprocating movement of the carriage 20 by the moving mechanism 30, causing the ink to land at any position on the surface of the medium P, thereby forming a desired image on the medium P.

[0020] 2. Functional configuration of the liquid ejection device Next, a description will be given of the functional configuration of the liquid ejection device 1. Fig. 2 is a diagram showing the functional configuration of the liquid ejection device 1. As shown in Fig. 2, the liquid ejection device 1 includes a control mechanism 10, a liquid ejection head 21, a carriage motor 31, a transport motor 41, and a linear encoder 90.

[0021] The control mechanism 10 includes a drive circuit 50 and a control circuit 100. The control circuit 100 includes a processor such as a microcontroller, for example. The control circuit 100 generates various data for controlling the liquid ejection device 1 and signals based on the data based on various signals such as image data input from a host computer or the like connected to an external device so as to be able to communicate with the outside, and outputs the generated data to a corresponding component.

[0022] A specific example of the operation of the control circuit 100 will be described. The control circuit 100 grasps the scanning position of the liquid ejection head 21 mounted on the carriage 20 based on a detection signal input from the linear encoder 90. Then, the control circuit 100 generates and outputs various signals according to the scanning position of the liquid ejection head 21. In detail, the control circuit 100 generates a control signal Ctrl-C for controlling the reciprocating movement of the liquid ejection head 21 and outputs it to the carriage motor 31. The control circuit 100 also generates a control signal Ctrl-T for controlling the transportation of the medium P and outputs it to the transport motor 41. Note that the control signal Ctrl-C may be converted via a driver circuit (not shown) and then input to the carriage motor 31, and similarly, the control signal Ctrl-T may be converted via a driver circuit (not shown) and then input to the transport motor 41.

[0023] In addition, the control circuit 100 generates head control signals DIA, DIB, change signals CHA, CHB, latch signal LAT, and clock signal SCK as control signals Ctrl-H for controlling the liquid ejection head 21 based on various signals such as image data input from the host computer and the scanning position of the liquid ejection head 21, and outputs them to the liquid ejection head 21.

[0024] In addition, the control circuit 100 outputs basic drive signals dA and dB, which are digital signals, to the drive circuit 50.

[0025] The drive circuit 50 includes a drive signal output circuit 51 and a reference voltage signal output circuit 52. The basic drive signals dA and dB are input to the drive signal output circuit 51. The drive signal output circuit 51 converts each of the basic drive signals dA and dB into a digital / analog signal, and then generates drive signals COMA and COMB as the drive signal COM by class D amplification. That is, the basic drive signal dA is a digital signal that defines the waveform of the drive signal COMA, and the basic drive signal dB is a digital signal that defines the waveform of the drive signal COMB. The drive signal output circuit 51 generates and outputs the drive signal COMA by performing class D amplification on the waveform defined by the basic drive signal dA, and generates and outputs the drive signal COMB by performing class D amplification on the waveform defined by the basic drive signal dB. That is, the drive signal output circuit 51 includes two sets of class D amplifier circuits. Note that the basic drive signals dA and dB may be signals that can define the waveforms of the drive signals COMA and COMB, and may be, for example, analog signals. Also, the drive signal output circuit 51 may be configured to include, for example, a class A amplifier circuit, a class B amplifier circuit, or a class AB amplifier circuit, as long as it can amplify the waveforms defined by the basic drive signals dA and dB.

[0026] The reference voltage signal output circuit 52 outputs a reference voltage signal VBS indicating the reference potential of the drive signals COMA and COMB. The reference voltage signal VBS may be, for example, a signal of ground potential with a voltage value of 0 V, or a DC voltage signal with a voltage value of 5.5 V, 6 V, or the like.

[0027] The driving signals COMA, COMB and the reference voltage signal VBS output by the driving circuit 50 are output to the liquid ejection head 21.

[0028] The liquid ejection head 21 includes a drive signal selection circuit 200, a memory circuit 250, and ejection units 600[1] to 600[m]. Note that the ejection units 600[1] to 600[m] all have the same configuration, and may be simply referred to as the ejection unit 600 when there is no need to distinguish between them.

[0029] The memory circuit 250 stores information about the liquid ejection head 21. Specifically, the memory circuit 250 stores various information, such as information about the usage status of the liquid ejection head 21, such as the number of ejection surfaces of the medium P onto which the liquid ejection head 21 ejects ink, the period of time that has elapsed since the liquid ejection head 21 was connected to the control mechanism 10, information about the manufacturing lot of the liquid ejection head 21, information about the initial characteristics of the ejection unit 600, and the like, as well as information for improving the driving accuracy of the liquid ejection head 21, such as variations in the characteristics of the ejection unit 600 of the liquid ejection head 21 and correction values ​​corresponding to the variations.

[0030] The head control signal DIA, the change signal CHA, the latch signal LAT, and the clock signal SCK are supplied to the memory circuit 250. The memory circuit 250 stores information transmitted based on the head control signal DIA, the change signal CHA, the latch signal LAT, and the clock signal SCK, and outputs information requested based on the head control signal DIA, the change signal CHA, the latch signal LAT, and the clock signal SCK to the control circuit 100 of the control mechanism 10 as read information MI.

[0031] The drive signal selection circuit 200 is configured as, for example, an integrated circuit device. The drive signal selection circuit 200 receives a clock signal SCK, a latch signal LAT, change signals CHA, CHB, head control signals DIA, DIB, and drive signals COMA, COMB. The drive signal selection circuit 200 generates drive signals VOUT[1] to VOUT[m] by selecting or not selecting the drive signals COMA, COMB based on the clock signal SCK, the latch signal LAT, the change signals CHA, CHB, and the input head control signals DIA, DIB, and outputs the drive signals VOUT[1] to VOUT[m] to the corresponding ejection sections 600[1] to 600[m]. When there is no need to distinguish between the drive signals VOUT[1] to VOUT[m], they may be simply referred to as drive signals VOUT.

[0032] The ejection section 600 has a piezoelectric element 60 to which a drive signal VOUT is supplied. Fig. 3 is a diagram for explaining a schematic configuration of the ejection section 600. As shown in Fig. 3, the ejection section 600 includes the piezoelectric element 60, a vibration plate 621, a cavity 631, and a nozzle 651. Cavity The nozzle 631 is filled with ink supplied from a reservoir 641. Ink is introduced into the reservoir 641 from the ink container 2 via a supply port 661.

[0033] The vibration plate 621 is displaced by the driving of the piezoelectric element 60 provided on the upper surface in FIG. 3. Then, the internal volume of the cavity 631 filled with ink expands and contracts with the displacement of the vibration plate 621. That is, the vibration plate 621 functions as a diaphragm that changes the internal volume of the cavity 631. The nozzle 651 is an opening provided in the nozzle plate 632, and communicates with the cavity 631. Then, as the internal volume of the cavity 631 changes, an amount of ink according to the change in the internal volume is introduced into the cavity 631 and ejected from the nozzle 651.

[0034] The piezoelectric element 60 has a structure in which a piezoelectric body 601 is sandwiched between a pair of electrodes 611 and 612. A drive signal VOUT is supplied to the electrode 611 of the piezoelectric element 60, and a reference voltage signal VBS is supplied to the electrode 612, whereby the central portions of the electrodes 611 and 612 of the piezoelectric body 601 are displaced in the vertical direction together with the diaphragm 621 in accordance with the potential difference between the voltages supplied by the electrodes 611 and 612. That is, the piezoelectric element 60 is driven by the supply of a drive signal VOUT based on the drive signals COMA and COMB.

[0035] In the ejection section 600 configured as above, when the piezoelectric element 60 bends upward, the vibration plate 621 is displaced upward, and the internal volume of the cavity 631 is expanded. As a result, the ink stored in the reservoir 641 is drawn into the cavity 631. On the other hand, when the piezoelectric element 60 bends downward, the vibration plate 621 is displaced downward, and the internal volume of the cavity 631 is reduced. Then, an amount of ink according to the degree of reduction in the internal volume of the cavity 631 is ejected from the nozzle 651 communicating with the cavity 631. Note that the structure of the piezoelectric element 60 is not limited to that shown in FIG. 3, and any structure may be used as long as ink can be ejected from the nozzle 651 in response to the driving of the piezoelectric element 60.

[0036] As described above, the liquid ejection device 1 in this embodiment includes a liquid ejection head 21 having a piezoelectric element 60 that ejects ink from a nozzle 651 by being driven by a drive signal VOUT generated based on the drive signals COMA and COMB, a drive signal selection circuit 200 that switches whether or not the drive signals COMA and COMB are supplied to the piezoelectric element 60, and a control mechanism 10 having a drive signal output circuit 51 that outputs the drive signals COMA and COMB, and a control circuit 100 that outputs a clock signal SCK, a latch signal LAT, a change signal CH, and head control signals DIA and DIB that control the drive signal selection circuit 200. The liquid ejection head 21 is controlled by the control mechanism 10, whereby ink is landed at a desired position on the medium P, thereby forming a desired image on the medium P.

[0037] Here, the piezoelectric element 60 is an example of a drive element, the drive signal selection circuit 200 is an example of a switching circuit, and the control mechanism 10 that controls the liquid ejection head 21 is an example of a liquid ejection head control circuit. Also, the control circuit 100 that outputs the clock signal SCK, latch signal LAT, change signal CH, and head control signals DIA and DIB that control the drive signal selection circuit 200 is an example of a switching control circuit. And the drive signal COMA output by the drive signal output circuit 51 is an example of a drive signal in this embodiment. Note that, although this embodiment will be described with an example of a case where the liquid ejection device 1 includes one liquid ejection head 21, the liquid ejection device 1 may include multiple liquid ejection heads 21.

[0038] 3. Drive signal selection circuit configuration Next, we will explain the configuration of the drive signal selection circuit 200. Fig. 4 is a diagram showing the configuration of the drive signal selection circuit 200. As shown in Fig. 4, the drive signal selection circuit 200 has selection control circuits 210a and 210b, and selection circuits 230[1] to 230[m].

[0039] The selection control circuit 210a receives a clock signal SCK, a latch signal LAT, a change signal CHA, and a head control signal DIA. Based on the clock signal SCK, the latch signal LAT, the change signal CHA, and the head control signal DIA, the selection control circuit 210a outputs selection signals Sa[1]-Sa[m] for switching whether or not each of the selection circuits 230[1]-230[m] described below outputs the drive signal COMA as the drive signal VOUT.

[0040] The selection control circuit 210b also receives a clock signal SCK, a latch signal LAT, a change signal CHB, and a head control signal DIB. Based on the clock signal SCK, the latch signal LAT, the change signal CHB, and the head control signal DIB, the selection control circuit 210b outputs selection signals Sb[1]-Sb[m] for switching whether or not each of the selection circuits 230[1]-230[m] described below outputs the drive signal COMB as the drive signal VOUT.

[0041] The selection circuits 230[1]-230[m] are provided corresponding to the discharge units 600[1]-600[m]. The selection circuits 230[1]-230[m] switch whether or not to output the drive signal COMA as the drive signals VOUT[1]-VOUT[m] based on the selection signals Sa[1]-Sa[m] output by the selection control circuit 210a, and switch whether or not to output the drive signal COMB as the drive signals VOUT[1]-VOUT[m] based on the selection signals Sb[1]-Sa[m] output by the selection control circuit 210b.

[0042] Specifically, the selection circuit 230[1] receives the selection signal Sa[1] output by the selection control circuit 210a, the selection signal Sb[1] output by the selection control circuit 210b, and the drive signals COMA and COMB. The selection circuit 230[1] generates the drive signal VOUT[1] by selecting or not selecting the drive signals COMA and COMB based on the selection signals Sa[1] and Sb[1], and outputs the drive signal VOUT[1] to the discharge section 600[1]. The selection circuit 230[m] receives the selection signal Sa[m] output by the selection control circuit 210a, the selection signal Sb[m] output by the selection control circuit 210b, and the drive signals COMA and COMB. The selection circuit 230[m] generates the drive signal VOUT[m] by selecting or not selecting the drive signals COMA and COMB based on the selection signals Sa[m] and Sb[m], and outputs the drive signal VOUT[m] to the discharge section 600[m]. That is, the selection signal Sa[i] output by the selection control circuit 210a, the selection signal Sb[i] output by the selection control circuit 210b, and the drive signals COMA and COMB are input to the selection circuit 230[i] (i is any of 1 to m). The selection circuit 230[i] then generates the drive signal VOUT[i] by selecting or not selecting the drive signals COMA and COMB based on the selection signals Sa[i] and Sb[i], and outputs it to the discharge section 600[i].

[0043] Next, a specific example of the configuration of the selection control circuits 210a and 210b will be described. The selection control circuits 210a and 210b have the same configuration, but only differ in the signals that are input and the signals that are output. Therefore, in the following description, when there is no need to distinguish between the selection control circuits 210a and 210b, they will be simply referred to as the selection control circuit 210. The selection control circuit 210 will be described as receiving the clock signal SCK, the latch signal LAT, the change signal CH, and the head control signal DI, and outputting the selection signals S[1] to S[m].

[0044] 5 is a diagram showing an electrical configuration of the selection control circuit 210. As shown in FIG. 5, the selection control circuit 210 has a control logic circuit 260 and m selection signal output units 270 provided corresponding to the m ejection units 600. That is, the selection control circuit 210 has m selection signal output units 270, the same number as the total number of ejection units 600 that output the drive signal VOUT. The selection control circuit 210 then outputs a drive signal VOUT to the drive control circuit 210. The drive signal VOUT is determined by the latch signal LAT and the change signal CH input thereto. At the timing, based on the head control signal DI propagated in synchronization with the clock signal SCK, selection signals S[1] to S[m] corresponding to each of the ejection sections 600[1] to 600[m] are generated and output to the corresponding selection circuits 230[1] to 230[m].

[0045] Here, in describing the electrical configuration of the selection control circuit 210, we will first describe the latch signal LAT, change signal CH, clock signal SCK, and head control signal DI that are input to the selection control circuit 210. Fig. 6 is a diagram for explaining the latch signal LAT, change signal CH, clock signal SCK, and head control signal DI.

[0046] The latch signal LAT is a pulse signal output by the control circuit 100 based on a signal indicating the scanning position of the carriage 20 carrying the liquid ejection head 21, output by the linear encoder 90. The liquid ejection head 21 ejects ink for forming dots on the medium between pulses of this latch signal LAT. This allows the liquid ejection head 21 to eject a predetermined amount of ink at a desired position on the medium P along the main scanning direction, and therefore allows dots of a desired size to be formed at a desired position on the medium P. The period from the rising edge of this latch signal LAT to the rising edge of the next latch signal corresponds to the dot formation period T for forming dots on the medium P. In other words, the latch signal LAT is a signal indicating the scanning position of the liquid ejection head 21 relative to the medium P, and is also a signal that defines the dot formation period T for forming dots on the medium P according to the scanning position of the liquid ejection head 21.

[0047] The change signal CH is a pulse signal that specifies the switching timing at which the drive signal selection circuit 200 switches whether or not to supply the drive signal COM to the discharge section 600 as the drive signal VOUT, and the control circuit 100 outputs the change signal CH so as to divide the dot formation period T into a plurality of periods. In this embodiment, the change signal CH is described as a pulse signal that is output only once in the dot formation period T. That is, in this embodiment, the change signal CH divides the dot formation period T into two periods, a period T1 and a period T2. Then, the drive signal selection circuit 200 switches whether or not to supply the drive signal COM to the discharge section 600 as the drive signal VOUT in the period T1, and switches whether or not to supply the drive signal COM to the discharge section 600 as the drive signal VOUT in the period T2. As a result, in the dot formation period T, the ink discharged in the period T1 and the ink discharged in the period T2 are combined on the medium P to form one dot.

[0048] As described above, the dot formation cycle T is divided into the period T1 and the period T2 using the change signal CH, and whether or not the drive signal COM is supplied to the discharge section 600 as the drive signal VOUT in the period T1 and whether or not the drive signal COM is supplied to the discharge section 600 as the drive signal VOUT in the period T2 are individually switched, so that the liquid discharge head 21 can form dots of four different sizes on the medium P. As a result, dots of four gradations can be formed on the medium P, and a high-definition image can be formed on the medium P. That is, the change signal CH specifies the switching timing of the drive signal selection circuit 200. Note that, in this embodiment, the change signal CH is described as dividing the dot formation cycle T into two periods T1 and T2, but the change signal CH may divide the dot formation cycle T into three or more periods depending on the material of the medium used, the physical properties of the ink, and further the user's request.

[0049] The head control signal DI is a signal synchronized with the clock signal SCK, and includes, in series, an ejection control signal SI that individually defines the amount of ink ejected onto the medium P by the nozzles 651 of each of the m ejection units 600, and a setting information signal SP for defining the relationship between the logical level of the selection signal S output during each of the periods T1 and T2 defined by the change signal CH and the ejection control signal SI. This head control signal DI is supplied to the selection control circuit 210 in the dot formation period T before the latch signal LAT rises in synchronization with the clock signal SCK, and the signals corresponding to the m ejection units 600 are stored in a register of the selection control circuit 210. The head control signals DI held in the register are latched all at once at the rising edge of the latch signal LAT, thereby defining the logic level of the selection signal S in the dot formation cycle T defined by including the latch signal LAT.

[0050] Here, the details of the head control signal DI, which includes the ejection control signal SI and the setting information signal SP, will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of the data configuration of the head control signal DI. As shown in Fig. 7, the head control signal DI includes the ejection control signal SI and the setting information signal SP, and the ejection control signal SI includes upper ejection data SIH and lower ejection data SIL.

[0051] Specifically, the discharge control signal SI is a serial signal of 2m bits in total, including two bits of data, namely, upper discharge data SIH and lower discharge data SIL, for controlling the driving of the piezoelectric element 60 included in the discharge unit 600, corresponding to each of the m discharge units 600. In detail, the discharge control signal SI includes m bits of upper discharge data SIH in serial in the order of upper discharge data SIH corresponding to the discharge unit 600[m], upper discharge data SIH corresponding to the discharge unit 600[m-1], ..., upper discharge data SIH corresponding to the discharge unit 600[1], and includes m bits of lower discharge data SIL after the upper discharge data SIH in serial in the order of lower discharge data SIL corresponding to the discharge unit 600[m], lower discharge data SIL corresponding to the discharge unit 600[m-1], ..., lower discharge data SIL corresponding to the discharge unit 600[1]. In the following description, the upper-order ejection data SIH corresponding to the ejection section 600[i] may be referred to as the upper-order ejection data SIHi, and the lower-order ejection data SIL corresponding to the ejection section 600[i] may be referred to as the lower-order ejection data SILi.

[0052] Then, the ejection unit 600[i] ejects an amount of ink defined by two bits, the upper ejection data SIHi and the lower ejection data SILi. That is, the ejection control signal SI controls the driving of the piezoelectric element 60 included in the ejection unit 600, thereby defining the amount of ink ejected from the nozzle 651. Here, in the following description, the upper ejection data SIH and the lower ejection data SIL corresponding to the ejection unit 600 may be referred to as ejection data [SIH, SIL], and the upper ejection data SIHi and the lower ejection data SILi corresponding to the ejection unit 600[i] may be referred to as ejection data [SIHi, SILi].

[0053] The setting information signal SP is a serial signal including data for defining the drive pattern of the piezoelectric element 60. Specifically, the setting information signal SP is a signal of 8 bits in total, including four types of setting information SP00-SP03 indicating the drive pattern of the piezoelectric element 60 determined by the discharge data [SIH, SIL] included in the discharge control signal SI in the period T1 defined by the change signal CH, and four types of setting information SP10-SP13 indicating the drive pattern of the piezoelectric element 60 determined by the combination of the discharge data [SIH, SIL] included in the discharge control signal SI in the period T2, serially included in the order of setting information SP13, SP12, SP11, SP10, SP03, SP02, SP01, SP00. That is, the setting information signal SP is the state of the drive signal selection circuit 200 in the periods T1 and T2 defined by the change signal CH, and specifically defines the relationship between the logic level of the selection signal S that defines the state of the selection circuits 230[1]-230[m] described later and the discharge data [SIH, SIL] included in the discharge control signal SI. In this embodiment, the setting information signal SP is described as an 8-bit signal, but it may be a signal of more than 8 bits or a signal of less than 8 bits depending on the number of periods divided by the change signal CH.

[0054] As described above, the control circuit 100 supplies the selection control circuit 210 with the latch signal LAT that determines the dot formation period T, the change signal CH that determines the switching timing at which the drive signal selection circuit 200 switches whether or not to supply the drive signal COM to the ejection unit 600 as the drive signal VOUT, and the amount of ink ejected from each of the m nozzles 651 onto the medium P. the selection circuits 230[1]-230[m] in each of periods T1 and T2; and a setting information signal SP for specifying the relationship between the logical level of the selection signal S, which specifies the state of the selection circuits 230[1]-230[m] in each of periods T1 and T2, and the ejection control signal SI. The selection circuits 230 output a clock signal SCK for propagating a head control signal DI which includes the ejection control signal SI and the setting information signal SP in series.

[0055] Returning to Fig. 5, the control logic circuit 260 includes an SP register group 261 and a selection control signal generation unit 262. The SP register group 261 includes a plurality of registers connected in series, and constitutes a so-called shift register that propagates the head control signal DI, which is input in synchronization with the clock signal SCK, to the register in the subsequent stage in sequence. When the supply of the clock signal SCK is stopped, the SP register group 261 holds the setting information SP00 to SP13 included in the setting information signal SP, among the head control signal DI. The selection control signal generation unit 262 latches the setting information SP00 to SP13 held in the SP register group 261 at the rising edge of the latch signal LAT, and translates the latched setting information SP00 to SP13 to generate a selection control signal Q1 that includes setting information SP00, SP01, SP02, SP03 and specifies the logical level of the selection signal S output from the selection control circuit 210 during the period T1, and a selection control signal Q2 that includes setting information SP10, SP11, SP12, SP13 and specifies the logical level of the selection signal S output from the selection control circuit 210 during the period T1, and outputs the signals to the decoders 226 included in each of the m selection signal output units 270.

[0056] Here, in the following description, the selection control signal Q1 including the setting information SP00, SP01, SP02, and SP03 may be referred to as the selection control signal Q1[SP00, SP01, SP02, SP03], and the selection control signal Q2 including the setting information SP10, SP11, SP12, and SP13 may be referred to as the selection control signal Q2[SP10, SP11, SP12, SP13].

[0057] Each of the m selection signal output units 270 includes a first register 222 a , a second register 222 b , a first latch circuit 224 a , a second latch circuit 224 b , and a decoder 226 .

[0058] The second register 222b included in each of the m selection signal output units 270 is serially connected to the rear stage of the SP register group 261 including a plurality of registers, and the first register 222a included in each of the m selection signal output units 270 is serially connected to the rear stage of the m serially connected second registers 222b. Specifically, the second register 222b included in the selection signal output unit 270 corresponding to the discharge unit 600[1] is connected to the rear stage of the SP register group 261. In addition, the second register 222b included in the selection signal output unit 270 corresponding to the discharge unit 600[2], the second register 222b included in the selection signal output unit 270 corresponding to the discharge unit 600[3], ..., the second register 222b included in the selection signal output unit 270 corresponding to the discharge unit 600[m] are serially connected in this order to the rear stage of the second register 222b included in the selection signal output unit 270 corresponding to the discharge unit 600[1]. The first register 222a included in the selection signal output unit 270 corresponding to the discharge unit 600[1] is connected to the rear stage of the second register 222b included in the selection signal output unit 270 corresponding to the discharge unit 600[m]. The first register 222a included in the selection signal output unit 270 corresponding to the discharge unit 600[2], the first register 222a included in the selection signal output unit 270 corresponding to the discharge unit 600[3], ..., the first register 222a included in the selection signal output unit 270 corresponding to the discharge unit 600[m] are connected in series to the rear stage of the first register 222a included in the selection signal output unit 270 corresponding to the discharge unit 600[1].

[0059] That is, the SP register group 261, the m second registers 222b included in each of the m selection signal output units 270, The m first registers 222a constitute a shift register. The head control signal DI input to the SP register group 261 is propagated to the subsequent stages in the order of the m second registers 222b included in each of the m selection signal output units 270 and the m first registers 222a included in each of the m selection signal output units 270 in synchronization with the clock signal SCK. Thereafter, the supply of the clock signal SCK is stopped, so that the second register 222b included in the selection signal output unit 270 corresponding to the ejection unit 600[i] holds the lower ejection data SILi corresponding to the ejection unit 600[i], and the first register 222a included in the selection signal output unit 270 corresponding to the ejection unit 600[i] holds the upper ejection data SIHi corresponding to the ejection unit 600[i].

[0060] The upper ejection data SIH held in the first register 222a of each of the m selection signal output units 270 is latched by the corresponding first latch circuit 224a at the rising edge of the latch signal LAT, and the lower ejection data SIL held in the second register 222b of each of the m selection signal output units 270 is latched by the corresponding second latch circuit 224b at the rising edge of the latch signal LAT. The first latch circuit 224a outputs the latched upper ejection data SIH to the decoder 226 as latch data LTa, and the second latch circuit 224b outputs the latched lower ejection data SIL to the decoder 226 as latch data LTb.

[0061] In the following description, the latch data LTa output by the first latch circuit 224a of the selection signal output unit 270 corresponding to the discharge unit 600[i] may be referred to as latch data LTai, and the latch data LTb output by the second latch circuit 224b of the selection signal output unit 270 corresponding to the discharge unit 600[i] may be referred to as latch data LTbi. Also, the latch data LTa, LTb may be referred to as latch data [LTa, LTb], and the latch data [LTa, LTb] corresponding to the discharge unit 600[i] may be referred to as latch data [LTai, LTbi].

[0062] The decoder 226 receives the selection control signals Q1 [SP00, SP01, SP02, SP03] and Q2 [SP10, SP11, SP12, SP13] output by the selection control signal generating unit 262, and the latch data [LTa, LTb] corresponding to the ejection data [SIH, SIL]. The decoder 226 generates a selection signal S based on the selection control signals Q1, Q2 and the latch data [LTa, LTb], and outputs it to the corresponding selection circuit 230.

[0063] 8 is a diagram showing the decoded contents of the decoder 226. As shown in FIG. 8, the decoder 226 selects a logic level defined by the selection control signal Q1 [SP00, SP01, SP02, SP03] in the period T1 and outputs it as the selection signal S, and selects a logic level defined by the selection control signal Q2 [SP10, SP11, SP12, SP13] in the period T2 and outputs it as the selection signal S. That is, the change signal CH that defines the period T1 and the period T2 defines the switching timing of whether the drive signal selection circuit 200 switches whether to supply the drive signals COMA and COMB to the piezoelectric element 60 based on the selection control signal Q1 [SP00, SP01, SP02, SP03] or whether to switch whether to supply the drive signals COMA and COMB to the piezoelectric element 60 based on the selection control signal Q2 [SP10, SP11, SP12, SP13].

[0064] Specifically, when ejection data [SIH, SIL]=[1,1] is input during a dot formation cycle T, the decoder 226 outputs the logical level of the setting information SP00 as the selection signal S during period T1, and outputs the logical level of the setting information SP10 as the selection signal S during period T2, in accordance with the contents defined by the selection control signals Q1 and Q2. Similarly, when ejection data [SIH, SIL]=[1,0] is input during a dot formation cycle T, the decoder 226 outputs the logical level of the setting information SP00 as the selection signal S during period T1, and outputs the logical level of the setting information SP10 as the selection signal S during period T2, in accordance with the contents defined by the selection control signals Q1 and Q2. When ejection data [SIH, SIL]=[0, 1] is input during the dot formation cycle T, the decoder 226 outputs the logical level of the setting information SP01 as the selection signal S during the period T1, and outputs the logical level of the setting information SP11 as the selection signal S during the period T2, in accordance with the contents defined by the selection control signals Q1 and Q2. When ejection data [SIH, SIL]=[0, 1] is input during the dot formation cycle T, the decoder 226 outputs the logical level of the setting information SP02 as the selection signal S during the period T1, and outputs the logical level of the setting information SP12 as the selection signal S during the period T2, in accordance with the contents defined by the selection control signals Q1 and Q2. When ejection data [SIH, SIL]=[0, 0] is input during the dot formation cycle T, the decoder 226 outputs the logical level of the setting information SP03 as the selection signal S during the period T1, and outputs the logical level of the setting information SP13 as the selection signal S during the period T2, in accordance with the contents defined by the selection control signals Q1 and Q2.

[0065] As described above, the selection control circuit 210 outputs selection signals S[1] to S[m] that control the states of the selection circuits 230[1] to 230[m] corresponding to the ejection sections 600[1] to 600[m], respectively, based on the clock signal SCK, the latch signal LAT, the change signal CH, and the head control signal DI. That is, in the drive signal selection circuit 200, the selection control circuit 210a outputs selection signals Sa[1] to Sa[m] that control the state of the selection circuits 230[1] to 230[m] corresponding to each of the ejection sections 600[1] to 600[m] based on the clock signal SCK, the latch signal LAT, the change signal CHA, and the head control signal DIA, and the selection control circuit 210b outputs selection signals Sb[1] to Sb[m] that control the state of the selection circuits 230[1] to 230[m] corresponding to each of the ejection sections 600[1] to 600[m] based on the clock signal SCK, the latch signal LAT, the change signal CHB, and the head control signal DIB.

[0066] Next, the configuration of the selection circuits 230[1] to 230[m] will be described. Here, the selection circuits 230[1] to 230[m] all have the same configuration. Therefore, when there is no need to distinguish between the selection circuits 230[1] to 230[m], they may be simply referred to as selection circuits 230. The following description will be given on the assumption that the selection circuit 230 receives a selection signal Sa among the selection signals Sa[1] to Sa[m] and a selection signal Sb among the selection signals Sb[1] to Sb[m].

[0067] Fig. 9 is a diagram showing the configuration of the selection circuit 230 corresponding to one of the discharge sections 600. As shown in Fig. 9, the selection circuit 230 has inverters 232a and 232b, which are NOT circuits, and transfer gates 234a and 234b.

[0068] The selection signal Sa output by the selection control circuit 210a is input to a positive control terminal of the transfer gate 234a that is not marked with a circle, and is also logically inverted by the inverter 232a and input to a negative control terminal of the transfer gate 234a that is marked with a circle. A drive signal COMA is supplied to the input terminal of the transfer gate 234a. Specifically, the transfer gate 234a makes the input terminal and output terminal conductive when the input selection signal Sa is at H level, and makes the input terminal and output terminal non-conductive when the input selection signal Sa is at L level.

[0069] The selection signal Sb output by the selection control circuit 210b is input to a positive control terminal of the transfer gate 234b that is not marked with a circle, and is also logically inverted by the inverter 232b and input to a negative control terminal of the transfer gate 234b that is marked with a circle. A drive signal COMB is supplied to the input terminal of the transfer gate 234b. Specifically, the transfer gate 234b provides electrical continuity between the input terminal and the output terminal when the input selection signal Sb is at an H level, and provides no electrical continuity between the input terminal and the output terminal when the input selection signal Sb is at an L level.

[0070] The output terminal of the transfer gate 234a and the output terminal of the transfer gate 234b are commonly connected, and the drive signal VOUT is output from the commonly connected connection point.

[0071] As described above, the drive signal selection circuit 200 in this embodiment selects or deselects the drive signals COMA, COMB based on the input clock signal SCK, latch signal LAT, change signals CHA, CHB, and head control signals DIA, DIB, thereby generating drive signals VOUT[1] to VOUT[m] and outputting them to the corresponding ejection sections 600[1] to 600[m].

[0072] 4. Control of liquid ejection head by control mechanism As described above, the drive signal selection circuit 200 in this embodiment generates the drive signals VOUT[1] to VOUT[m] by selecting or deselecting the drive signals COMA and COMB based on the input clock signal SCK, latch signal LAT, change signals CHA and CHB, and head control signals DIA and DIB, and outputs them to the corresponding ejection units 600[1] to 600[m]. That is, the control mechanism 10 controls the drive signal selection circuit 200 using the clock signal SCK, latch signal LAT, change signals CHA and CHB, and head control signals DIA and DIB to supply the drive signals VOUT[1] to VOUT[m] based on the drive signals COMA and COMB to the ejection units 600[1] to 600[m], respectively, and causes the corresponding ejection units 600[1] to 600[m] to eject ink.

[0073] 2, the control mechanism 10 controls the memory circuit 250 of the liquid ejection head 21 using the clock signal SCK, the latch signal LAT, the change signal CH, and the head control signal DIA, thereby storing desired information in the memory circuit 250 and also reading out the information stored in the memory circuit 250. That is, the control mechanism 10 controls both the drive signal selection circuit 200 of the liquid ejection head 21 and the memory circuit 250 of the liquid ejection head 21 using the clock signal SCK, the latch signal LAT, the change signals CHA, CHB, and the head control signals DIA, DIB.

[0074] That is, in the liquid ejection device 1 of this embodiment, the control mechanism 10 has an ejection control period in which it controls the liquid ejection head 21 to eject ink from the nozzles 651, and a non-ejection control period in which it controls the liquid ejection head 21 so that ink is not ejected from the nozzles 651. The control mechanism 10 outputs a head control signal DIA containing different data in the ejection control period and the non-ejection control period, thereby reducing the risk of malfunction of the liquid ejection device 1 even when the drive signal selection circuit 200 and the memory circuit 250 of the liquid ejection head 21 are controlled using common signals, the clock signal SCK, the latch signal LAT, the change signals CHA, CHB, and the head control signals DIA, DIB.

[0075] The operation of the control mechanism 10 and the liquid ejection head 21 during the ejection control period and the non-ejection control period, and specific examples of the head control signals DIA and DIB output by the control mechanism will be described. First, the details of the control of the liquid ejection head 21 performed by the control mechanism 10 during the ejection control period will be described. In describing the details of the control of the liquid ejection head 21 performed by the control mechanism 10 during the ejection control period, an example of the waveforms of the drive signals COMA and COMB output by the drive signal output circuit 51 to eject ink from the nozzles 651 will be described. Then, the control of the liquid ejection head 21 during the ejection control period will be described. In the following description, the period T1 divided by the change signal CHA of the dot formation period T defined by the latch signal LAT may be referred to as the period Ta1, the period T2 as the period Ta2, the period T1 divided by the change signal CHB as the period Tb1, and the period T2 as the period Tb2.

[0076] Fig. 10 is a diagram showing an example of the waveforms of the drive signals COMA and COMB. As shown in Fig. 10, the drive signal COMA includes a waveform formed by successively inserting a trapezoidal waveform Adp1 arranged in a period Ta1 from when the latch signal LAT rises until when the change signal CHA rises, and a trapezoidal waveform Adp2 arranged in a period Ta2 from when the change signal CHA rises until when the latch signal LAT rises. The trapezoidal waveform Adp1 is a waveform for ejecting a small amount of ink from the nozzle 651, and the trapezoidal waveform Adp2 is a waveform for ejecting a medium amount of ink, which is greater than a small amount, from the nozzle 651.

[0077] The drive signal COMB also includes a waveform formed by successively inserting a trapezoidal waveform Bdp1 arranged in a period Tb1 from when the latch signal LAT rises until when the change signal CHB rises, and a trapezoidal waveform Bdp2 arranged in a period Tb2 from when the change signal CHB rises until when the latch signal LAT rises. The trapezoidal waveform Bdp1 is a waveform that does not cause ink to be ejected from the nozzle 651, and is a waveform that causes the ink near the opening of the nozzle 651 to vibrate slightly, thereby preventing an increase in ink viscosity. Similarly to the trapezoidal waveform Adp1, the trapezoidal waveform Bdp2 is a waveform that causes a small amount of ink to be ejected from the nozzle 651.

[0078] 10, the voltage at the start timing and end timing of each of the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2 is a common voltage Vc. That is, each of the trapezoidal waveforms Adp1, Adp2, Bdp1, and Bdp2 starts and ends at the voltage Vc.

[0079] 10, the trapezoidal waveform Adp1 and the trapezoidal waveform Bdp2 are illustrated as having the same waveform, but the trapezoidal waveform Adp1 and the trapezoidal waveform Bdp2 may be different waveforms. In addition, in the description, a small amount of ink is ejected from the corresponding nozzle 651 when the trapezoidal waveform Adp1 is supplied to the ejection section 600 and when the trapezoidal waveform Bdp1 is supplied to the ejection section 600, but different amounts of ink may be ejected. In other words, the waveforms of the drive signals COMA and COMB are not limited to the waveforms shown in FIG. 10, and various waveforms may be combined depending on the moving speed of the carriage 20 on which the liquid ejection head 21 is mounted, the properties of the ink supplied to the liquid ejection head 21, the material of the medium P, and the like.

[0080] Next, the operation of the control mechanism 10 in controlling the liquid ejection head 21 during the ejection control period will be described. FIG. 11 is a diagram showing an example of the head control signals DIA and DIB output by the control mechanism 10 during the ejection control period. Here, as described above, the ejection control signals SI included in the head control signals DIA and DIB are signals that specify the amount of ink ejected for each of the m nozzles 651, and the logical level changes appropriately during the ejection control period. That is, the ejection data [SIH, SIL] included in the ejection control signal SI is either 0 or 1 depending on the amount of ink ejected from the corresponding nozzle 651 in the dot formation cycle T. Therefore, in FIG. 11, either 0 or 1 is illustrated as "0 / 1". In the following description, "1" means an H level signal and "0" means an L level signal.

[0081] 11, during the discharge control period, the control mechanism 10 outputs to the selection control circuit 210a the head control signal DIA including the setting information signal SP in which the setting information SP00, SP01, SP02, SP03, SP10, SP11, SP12, and SP13 are "1", "1", "0", "0", "1", "0", "0", "0", respectively. Therefore, the selection control signal generating unit 262 included in the control logic circuit 260 of the selection control circuit 210a generates the selection control signal Q1[SP00, SP01, SP02, SP03]=[1,1,0,0] and the selection control signal Q2[SP10, SP11, SP12, SP13]=[1,0,0,0] based on the setting information signal SP, and outputs them to the decoder 226.

[0082] Fig. 12 is a diagram showing the contents of the decode in the decoder 226 of the selection control circuit 210a during the discharge control period. As shown in Fig. 12, when discharge data [SIH, SIL] = [1, 1] is input, the decoder 226 outputs a selection signal Sa of H level in period T1 and H level in period T2, when discharge data [SIH, SIL] = [1, 0] is input, the decoder 226 outputs a selection signal Sa of H level in period T1 and L level in period T2, when discharge data [SIH, SIL] = [0, 1] is input, the decoder 226 outputs a selection signal Sa of L level in period T1 and L level in period T2, when discharge data [SIH, SIL] = [0, 0] is input, the decoder 226 outputs a selection signal Sa of L level in period T1 and L level in period T2.

[0083] 11, during the discharge control period, the control mechanism 10 outputs to the selection control circuit 210b the head control signal DIB including the setting information signal SP in which the setting information SP00, SP01, SP02, SP03, SP10, SP11, SP12, and SP13 are "0", "0", "0", "1", "0", "1", "1", "0", to the selection control circuit 210b. Therefore, the selection control signal generation unit 262 included in the control logic circuit 260 of the selection control circuit 210b generates the selection control signal Q1 [SP00, SP01, SP02, SP03] = [0, 0, 0, 1] and the selection control signal Q2 [SP10, SP11, SP12, SP13] = [0, 1, 1, 0] based on the setting information signal SP, and outputs them to the decoder 226.

[0084] Fig. 13 is a diagram showing the decoded contents in the decoder 226 of the selection control circuit 210b during the discharge control period. As shown in Fig. 13, when discharge data [SIH, SIL] = [1, 1] is input, the decoder 226 outputs a selection signal Sb of L level in period T1 and L level in period T2, when discharge data [SIH, SIL] = [1, 0] is input, the decoder 226 outputs a selection signal Sb of L level in period T1 and H level in period T2, when discharge data [SIH, SIL] = [0, 1] is input, the decoder 226 outputs a selection signal Sb of L level in period T1 and H level in period T2, when discharge data [SIH, SIL] = [0, 0] is input, the decoder 226 outputs a selection signal Sb of H level in period T1 and L level in period T2.

[0085] FIG. 14 is a diagram for explaining the operation of the selection circuit 230 when the selection signals Sa and Sb shown in FIGS. 12 and 13 are supplied. As shown in FIG. 14, in the case of the ejection data [SIH, SIL]=[1, 1], the transfer gate 234a is supplied with the H-level selection signal Sa in the period Ta1, and the H-level selection signal Sa is supplied in the period Ta2. On the other hand, the transfer gate 234b is continuously supplied with the L-level selection signal Sb in the dot formation cycle T. Therefore, in the dot formation cycle T, the corresponding piezoelectric element 60 is supplied with the drive signal VOUT in which the trapezoidal waveform Adp1 and the trapezoidal waveform Adp2 are successively formed. As a result, a small amount of ink and a medium amount of ink are ejected from the nozzle 651 and land on the medium P. Thereafter, the small amount of ink and the medium amount of ink that landed on the medium P are combined to form a large dot on the medium P.

[0086] Moreover, when the ejection data [SIH, SIL]=[1, 0], the transfer gate 234a is supplied with an H-level selection signal Sa in the period Ta1, and with an L-level selection signal Sa in the period Ta2. The transfer gate 234b is supplied with an L-level selection signal Sb in the period Tb1, and with an H-level selection signal Sa in the period Tb2. Thus, in the dot formation cycle T, the corresponding piezoelectric element 60 is supplied with a drive signal VOUT in which a trapezoidal waveform Adp1 and a trapezoidal waveform Bdp2 are successively formed. As a result, a small amount of ink is ejected from the nozzle 651 in two separate ejections, and lands on the medium P. Thereafter, the small amount of ink that has landed on the medium P is combined with the small amount of ink to form a medium dot on the medium P.

[0087] Furthermore, when the ejection data [SIH, SIL] = [0, 1], the transfer gate 234a is continuously supplied with an L-level selection signal Sa during the dot formation cycle T. On the other hand, the transfer gate 234b is supplied with an L-level selection signal Sb during period Tb1, and with an H-level selection signal Sb during period Tb2. Thus, during the dot formation cycle T, the corresponding piezoelectric element 60 is supplied with a drive signal VOUT having a constant waveform and a trapezoidal waveform Bdp2 in succession at voltage Vc. As a result, a small amount of ink is ejected once from the nozzle 651 and lands on the medium P. Thus, a small dot is formed on the medium P.

[0088] Furthermore, when the ejection data [SIH, SIL] = [0, 0], the transfer gate 234a is continuously supplied with the L-level selection signal Sa during the dot formation cycle T. On the other hand, the transfer gate 234b is supplied with the H-level selection signal Sb during the period Tb1, and with the L-level selection signal Sb during the period Tb2. Therefore, during the dot formation cycle T, the corresponding piezoelectric element 60 is supplied with the drive signal VOUT, which is a succession of the trapezoidal waveform Bdp1 and a constant waveform at voltage Vc. In this case, only the vicinity of the nozzle 651 vibrates slightly, and ink is not ejected from the nozzle 651. Therefore, no dots are formed on the medium P.

[0089] As described above, during the ejection control period, the control mechanism 10 outputs head control signals DIA and DIB as shown in FIG. 11 to the liquid ejection head 21, and the liquid ejection head 21 forms four types of dots, large dots, medium dots, small dots, and non-printing dots, on the medium P based on the ejection control signal SI and the setting information signal SP.

[0090] Next, an operation in which the control mechanism 10 controls the liquid ejection head 21 during a non-ejection control period and in which the control mechanism 10 obtains information stored in the memory circuit 250 will be described.

[0091] 15 is a diagram showing an example of the operation when the control mechanism 10 acquires information stored in the memory circuit 250. As shown in FIG. 15, when the control mechanism 10 acquires information stored in the memory circuit 250, first, the control mechanism 10 generates a trigger signal Tr that sets the logic levels of the latch signal LAT and the change signal CHA to a predetermined logic level, and outputs it to the memory circuit 250. As a result, the memory circuit 250 becomes accessible, allowing the reading of the stored information and the writing of predetermined information. Here, it is preferable that the trigger signal Tr includes a logic level that the logic levels of the latch signal LAT and the change signal CHA cannot take during the discharge control period, and for example, the trigger signal Tr in this embodiment includes a state in which the logic levels of both the latch signal LAT and the change signal CHA are H level.

[0092] After the memory circuit 250 becomes accessible based on the trigger signal Tr, the control mechanism 10 outputs, in synchronization with the clock signal SCK, to the memory circuit 250, a head control signal DIA including a command signal CMD for acquiring information held in the memory circuit 250 or for writing predetermined information to the memory circuit 250. As a result, information corresponding to the command signal CMD is stored in the memory circuit 250, and the information corresponding to the command signal CMD is read out as read information MI.

[0093] Here, the head control signal DIA including the command signal CMD output by the control mechanism 10 during the non-ejection control period is also supplied to the drive signal selection circuit 200. As a result, signals corresponding to the command signal CMD are held in the m first registers 222a, the m second registers 222b, and the SP register group 261 of the drive signal selection circuit 200. Furthermore, as described above, the control mechanism 10 makes the memory circuit 250 accessible by the trigger signal Tr that sets the logical levels of the latch signal LAT and the change signal CHA to a predetermined logical level, so that at the rising edge of the change signal CHA or the rising edge of the latch signal LAT, the information held in the m first registers 222a, the m second registers 222b, and the SP register group 261 is latched all at once and input to the decoder 226. As a result, the selection control circuit 210a outputs an unintended selection signal Sa to the selection circuit 230, and as a result, the selection circuit 230 supplies an unintended voltage as the drive signal VOUT to the piezoelectric element 60. That is, an unintended voltage is supplied to the piezoelectric element 60.

[0094] If an unintended voltage is supplied to the piezoelectric element 60 during the non-ejection control period, an unintended displacement occurs in the piezoelectric element 60, which may result in the liquid ejection head 21 erroneously ejecting ink. Furthermore, if an unintended voltage is continuously supplied to the piezoelectric element 60, an abnormality occurs in the piezoelectric element 60, which may result in a decrease in the ink ejection accuracy in the liquid ejection head 21. In other words, there is a risk that the liquid ejection device 1 may malfunction.

[0095] To address this problem, in the liquid ejection device 1 of this embodiment, by making improvements to the data configuration of the head control signals DIA, DIB output by the control mechanism 10 during the non-ejection control period, the control mechanism 10 reduces the risk that the configuration of the liquid ejection device 1 will become complicated and the risk that it will become difficult to miniaturize the liquid ejection device 1, while also reducing the risk of an unintended voltage being supplied to the piezoelectric element 60 during the non-ejection control period.

[0096] Fig. 16 is a diagram showing an example of head control signals DIA, DIB output by the control mechanism 10 during the non-ejection control period. As shown in Fig. 16, the control mechanism 10 generates head control signals DIA, DIB in which a pseudo setting information signal DSP is serially added to the rear of a p-bit command signal CMD during the non-ejection control period, and outputs the head control signals DIA, DIB to the liquid ejection head 21.

[0097] The pseudo setting information signal DSP includes pseudo setting information dq00-dq13 with the same number of bits as the setting information signal SP included in the head control signals DIA, DIB output by the control mechanism 10 during the discharge control period. That is, the pseudo setting information dq00, dq01, dq02, dq03, dq10, dq11, dq12, dq13 included in the pseudo setting information signal DSP correspond to the setting information SP00, SP01, SP02, SP03, SP10, SP11, SP12, SP13 included in the setting information signal SP, respectively. As a result, when the supply of the clock signal SCK that propagates the head control signals DIA and DIB is stopped during the non-ejection control period, the SP register group 261 possessed by each of the selection control circuits 210a and 210b retains pseudo setting information dq00, dq01, dq02, dq03, dq10, dq11, dq12, and dq13.

[0098] Then, when the latch signal LAT rises, the selection control signal generating unit 262 simultaneously latches and translates the pseudo setting information dq00, dq01, dq02, dq03, dq10, dq11, dq12, dq13 to generate a pseudo selection control signal DQ1 [dq00, dq01, dq02, dq03] corresponding to the selection control signal Q1 and a pseudo selection control signal DQ2 [dq10, dq11, dq12, dq13] corresponding to the selection control signal Q2, and outputs them to the decoder 226. That is, the control mechanism 10 outputs the head control signals DIA and DIB to which the pseudo setting information signal DSP is serially added after the p-bit command signal CMD during the non-ejection control period, thereby being able to specify the state of the drive signal selection circuit 200 during the periods Ta1, Ta2, Tb1, and Tb2 specified by the change signals CHA and CHB during the non-ejection control period. Therefore, even if the control circuit 100 outputs head control signals DIA and DIB including a p-bit command signal CMD to control the memory circuit 250 during the non-ejection control period, the risk of the state of the drive signal selection circuit 200 becoming unstable is reduced, and as a result, there is a risk of an unintended voltage being supplied to the piezoelectric element 60. This reduces leakage.

[0099] 16, the head control signal DIA during the non-ejection control period includes pseudo setting information [dq00, dq01, dq02, dq03, dq10, dq11, dq12, dq13]=[1,1,1,1,1,1,1,1]. Therefore, the pseudo selection control signal DQ1 output based on the head control signal DIA is pseudo selection control signal DQ1[dq00, dq01, dq02, dq03]=[1,1,1,1], and the pseudo selection control signal DQ2 is pseudo selection control signal DQ2[dq10, dq11, dq12, dq13]=[1,1,1,1]. In other words, during the non-ejection control period, the control circuit 100 outputs the pseudo selection control signal DQ1 and the pseudo selection control signal DQ2, which are the same pseudo setting information signal DSP, and the logical levels of the pseudo setting information dq00, dq01, dq02, dq03, dq10, dq11, dq12, and dq13 contained in the pseudo selection control signal DQ1 and the pseudo selection control signal DQ2 are all the same.

[0100] Fig. 17 is a diagram showing the decoded contents in the decoder 226 of the selection control circuit 210a during the non-ejection control period. As shown in Fig. 17, during the non-ejection control period, the decoder 226 of the selection control circuit 210a outputs an H-level selection signal Sb during periods T1 and T2, regardless of the logic level of the ejection data [SIH, SIL]. That is, in the liquid ejection device 1 of this embodiment, the selection control circuit 210a outputs an H-level selection signal Sb regardless of the periods Ta1, Ta2 defined by the change signal CHA and the logic level of the latch data [LTa, LTb].

[0101] 16, the head control signal DIB during the non-ejection control period includes pseudo setting information [dq00, dq01, dq02, dq03, dq10, dq11, dq12, dq13]=[0,0,0,0,0,0,0,0]. Therefore, the pseudo selection control signal DQ1 output based on the head control signal DIB is pseudo selection control signal DQ1[dq00, dq01, dq02, dq03]=[0,0,0,0], and the pseudo selection control signal DQ2 is pseudo selection control signal DQ2[dq10, dq11, dq12, dq13]=[0,0,0,0]. In other words, during the non-ejection control period, the control circuit 100 outputs the pseudo selection control signal DQ1 and the pseudo selection control signal DQ2, which are the same pseudo setting information signal DSP, and the logical levels of the pseudo setting information dq00, dq01, dq02, dq03, dq10, dq11, dq12, and dq13 contained in the pseudo selection control signal DQ1 and the pseudo selection control signal DQ2 are all the same.

[0102] Fig. 18 is a diagram showing the decoded contents in the decoder 226 of the selection control circuit 210b during the non-ejection control period. As shown in Fig. 18, during the non-ejection control period, the decoder 226 of the selection control circuit 210b outputs an L-level selection signal Sb during periods T1 and T2, regardless of the logic level of the ejection data [SIH, SIL]. That is, in the liquid ejection device 1 of this embodiment, the selection control circuit 210b outputs an L-level selection signal Sb during periods Tb1, Tb2 defined by the change signal CHB, and regardless of the logic level of the latch data [LTa, LTb].

[0103] As described above, during the non-ejection control period, the control circuit 100 outputs the pseudo selection control signal DQ1 and the pseudo selection control signal DQ2, which are the same pseudo setting information signal DSP, and the pseudo setting information dq00, dq01, dq02, dq03, dq10, dq11, dq12, dq13 contained in the pseudo selection control signal DQ1 and the pseudo selection control signal DQ2 all have the same logical levels, thereby being able to specify the state of the drive signal selection circuit 200 regardless of the periods Ta1, Ta2, Tb1, Tb2 specified by the change signals CHA, CHB and the logical level of the latch data [LTa, LTb]. In other words, even during the non-ejection control period, the state of the drive signal selection circuit 200 can be specified. As a result, there is a reduced risk of an unintended voltage being supplied to the piezoelectric element 60. That is, even when the head control signals DIA, DIB for controlling the ejection of ink from the liquid ejection head 21 during the ejection control period are used to control the memory circuit 250 of the liquid ejection head 21, there is a reduced risk of an unintended voltage being applied to the piezoelectric element 60 of the liquid ejection head 21, and as a result, there is a reduced risk of the liquid ejection head 21 malfunctioning.

[0104] Here, as shown in this embodiment, the logical levels of the pseudo setting information dq00 to dq13 of the pseudo setting information signal DSP included in the head control signals DIA and DIB input during the non-ejection control period are all the same in the head control signal DIA, and preferably all the same in the head control signal DIB, but it is sufficient that at least the logical level of the setting information SP00 to SP13 of the setting information signal SP included in the head control signals DIA and DIB input during the ejection control period is different from the logical level of the pseudo setting information dq00 to dq13 of the pseudo setting information signal DSP included in the head control signals DIA and DIB input during the non-ejection control period.

[0105] Since the logical levels of the setting information SP00 to SP13 and the pseudo setting information dq00 to dq13 are different, the selection control signal generating unit 262 can determine that the held information is not information requesting switching of the drive signal selection circuit 200. Therefore, when pseudo setting information dq00 to dq13 different from the logical levels of the setting information SP00 to SP13 is input, it can be translated into pseudo selection control signals DQ1 and DQ2 in which the states of the selection signals Sa and Sb do not switch. That is, since the logical levels of the setting information SP00 to SP13 of the setting information signal SP included in the head control signals DIA and DIB input at least during the ejection control period are different from the logical levels of the pseudo setting information dq00 to dq13 of the pseudo setting information signal DSP included in the head control signals DIA and DIB input during the non-ejection control period, the risk of an unintended voltage being applied to the piezoelectric element 60 of the liquid ejection head 21 is reduced, and as a result, the risk of malfunction of the liquid ejection head 21 can be reduced.

[0106] Furthermore, in this embodiment, the control of the memory circuit 250 has been described as an example of the control of the liquid ejection head 21 performed by the control mechanism 10 during the non-ejection control period, but the control of the liquid ejection head 21 performed by the control mechanism 10 during the non-ejection control period is not limited to this, and similar effects can be achieved, for example, even if a diagnostic circuit is provided to diagnose whether the liquid ejection head 21 is capable of operating normally and the diagnostic circuit is controlled based on the head control signals DIA, DIB.

[0107] Here, the discharge control period is an example of the first period, and the non-discharge control period is an example of the second period. Also, the change signal CHA, which is a switching timing of the selection circuit 230 of the drive signal selection circuit 200, specifies the timing of switching the logical level of the selection signal Sa from the logical level specified by the selection control signal Q1 to the logical level specified by the selection control signal Q2 during the discharge control period, and the timing of switching from the logical level specified by the pseudo selection control signal DQ1 to the logical level specified by the pseudo selection control signal DQ2 during the non-discharge control period, is an example of a switching timing signal, and the setting information signal SP and the pseudo setting information signal DSP, which specify the state of the drive signal selection circuit 200 during the period Ta1 and the period Ta2, which are examples of the control period specified by the change signal CHA, are examples of state selection signals.

[0108] In addition, the setting information SP00 to SP03 which is 4-bit data included in the selection control signal Q1 in the setting information signal SP, and the pseudo setting information dq00 to dq03 which is 4-bit data included in the pseudo selection control signal DQ1 in the pseudo setting information signal DSP are examples of n-bit first data, and the setting information SP10 to SP13 which is 4-bit data included in the selection control signal Q2, and the pseudo setting information dq10 to dq13 which is 4-bit data included in the pseudo selection control signal DQ2 in the pseudo setting information signal DSP are examples of n-bit second data. Here is one example.

[0109] In addition, the number of data contained in the selection control signals Q1, Q2 in the setting information signal SP, and the number of data contained in the pseudo selection control signals DQ1, DQ2 in the pseudo setting information signal DSP are not limited to 4 bits, but may be more than 4 bits depending on the number of divisions into which the dot formation period T is divided by the change signals CHA, CHB, and the number of types of dot sizes formed on the medium.

[0110] 5. Effects As described above, the control mechanism 10 of the liquid ejection device 1 in this embodiment outputs a setting information signal SP that defines the state of the drive signal selection circuit 200 in the periods Ta1 and Ta2 defined by the change signal CHA during an ejection control period in which the liquid ejection head 21 is controlled so that ink is ejected from the nozzle 651, and a pseudo setting information signal DSP that defines the state of the drive signal selection circuit 200 in the periods Ta1 and Ta2 defined by the change signal CHA during a non-ejection control period in which the liquid ejection head 21 is controlled so that ink is not ejected from the nozzle 651. In this case, by making the setting information signal SP and the pseudo setting information signal DSP signals containing different data, it is possible to fix the operation of the drive signal selection circuit 200 when the pseudo setting information signal DSP is supplied to the drive signal selection circuit 200. As a result, during a non-ejection control period in which the liquid ejection head 21 is controlled so that ink is not ejected from the nozzle 651, the operation of the drive signal selection circuit 200 of the liquid ejection head 21 becomes indefinite, and as a result, the risk of an unintended voltage being applied to the piezoelectric element 60 is reduced. That is, it is possible to reduce the risk of malfunction occurring in the liquid ejection device 1 including the control mechanism 10 in this embodiment.

[0111] In addition, in the liquid ejection device 1 of this embodiment, the logical level of the pseudo selection control signal DQ1 included in the pseudo setting information signal DSP that defines the state of the drive signal selection circuit 200 in the period Ta1 defined by the change signal CHA is the same as that of the pseudo selection control signal DQ2 included in the pseudo setting information signal DSP that defines the state of the drive signal selection circuit 200 in the period Ta2 defined by the change signal CHA, so that even if a new period based on the change signal CHA is defined in the non-ejection control period, the operating state of the drive signal selection circuit 200 of the liquid ejection head 21 can be fixed. Therefore, the simple configuration reduces the risk of an unintended voltage being applied to the piezoelectric element 60. That is, the liquid ejection device 1 equipped with the control mechanism 10 of this embodiment can reduce the risk of malfunction.

[0112] Furthermore, in the liquid ejection device 1 of this embodiment, by making all the logical levels of the pseudo selection control signal DQ1 included in the pseudo setting information signal DSP that defines the state of the drive signal selection circuit 200 in the period Ta1 defined by the change signal CHA the same, it is possible to fix the operating state of the drive signal selection circuit 200 of the liquid ejection head 21 regardless of the signal input to the drive signal selection circuit 200 in the non-ejection control period. Therefore, with a simple configuration, the risk of an unintended voltage being applied to the piezoelectric element 60 is further reduced. In other words, it is possible to further reduce the risk of malfunction occurring in the liquid ejection device 1 equipped with the control mechanism 10 of this embodiment.

[0113] Although the embodiments and modifications have been described above, the present invention is not limited to these embodiments, and can be embodied in various forms without departing from the spirit of the present invention. For example, the above embodiments can be appropriately combined.

[0114] The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same purpose and effect). The present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that have the same effects as the configurations described in the embodiments or that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

[0115] The following can be derived from the above-described embodiment and modified examples.

[0116] One aspect of the liquid ejection head control circuit is A liquid ejection head control circuit for controlling a liquid ejection head having a drive element that is driven based on a drive signal to eject liquid from a nozzle, and a switching circuit that switches whether or not the drive signal is supplied to the drive element, A drive signal output circuit that outputs the drive signal; A switching control circuit for controlling the switching circuit; Equipped with The switching control circuit includes: a discharge control signal that defines the amount of liquid discharged from the nozzle; A switching timing signal that defines a switching timing of the switching circuit; a state selection signal that defines a state of the switching circuit during a control period defined by the switching timing signal; and The state selection signal in a first period for controlling the liquid ejection head so that liquid is ejected from the nozzle is different from the state selection signal in a second period for controlling the liquid ejection head so that liquid is not ejected from the nozzle.

[0117] According to this liquid ejection head control circuit, the state selection signal during a first period that controls the liquid ejection head so that liquid is ejected from the nozzle is different from the state selection signal during a second period that controls the liquid ejection head so that liquid is not ejected from the nozzle, thereby reducing the risk of the state of the switching circuit switching at an unintended timing, and as a result, reducing the risk of malfunction of the liquid ejection device.

[0118] In one aspect of the liquid ejection head control circuit, the state selection signal includes n-bit first data and n-bit second data; The switching control circuit may output the state selection signal in which the first data and the second data are the same during the second period.

[0119] According to this liquid ejection head control circuit, the switching control circuit outputs a state selection signal in which the n-bit first data and the n-bit second data included in the state selection signal are the same during the second period, so that even if a signal that switches between the first data and the second data is input to the liquid ejection head at an unintended timing, the risk of the switching circuit switching the state is reduced, thus further reducing the risk of malfunction of the liquid ejection device.

[0120] In one aspect of the liquid ejection head control circuit, The n bits of the first data may all have the same logic level.

[0121] According to this liquid ejection head control circuit, the n-bit first data included in the state selection signal and the n-bit second data included in the state selection signal are the same state selection signal during the second period, and the switching control circuit outputs a state selection signal in which the n-bit logic levels of the first data are all the same, thereby reducing the risk of the state of the switching circuit switching even if an unintended signal is input to the liquid ejection head. Therefore, the risk of malfunction of the liquid ejection device is reduced. This reduces it further.

[0122] In one aspect of the liquid ejection head control circuit, The switching timing signal may specify the switching timing of whether the switching circuit switches whether to supply the drive signal to the drive element based on the first data, or whether to supply the drive signal to the drive element based on the second data.

[0123] According to this liquid ejection head control circuit, even if the switching timing signal specifies the timing of whether the switching circuit switches whether to supply a drive signal to the drive element based on first data, or whether to supply a drive signal to the drive element based on second data, the risk of the switching circuit switching states is reduced, thereby reducing the risk of malfunction of the liquid ejection device.

[0124] In one aspect of the liquid ejection head control circuit, The liquid ejection head has a memory circuit, The switching control circuit may control the memory circuit in the second period.

[0125] According to this liquid ejection head control circuit, even when control of the memory circuit is executed in the second period, the risk of the switching circuit switching the state is reduced, thereby reducing the risk of malfunction of the liquid ejection device.

[0126] One aspect of the liquid ejection device is a liquid ejection head including a drive element that is driven based on a drive signal to eject liquid from a nozzle, and a switching circuit that switches whether or not the drive signal is supplied to the drive element; a liquid ejection head control circuit for controlling the liquid ejection head; Equipped with The liquid ejection head control circuit includes: A drive signal output circuit that outputs the drive signal; A switching control circuit for controlling the switching circuit; Equipped with The switching control circuit includes: a discharge control signal that defines the amount of liquid discharged from the nozzle; A switching timing signal that defines a switching timing of the switching circuit; a state selection signal that defines a state of the switching circuit during a control period defined by the switching timing signal; and The state selection signal in a first period for controlling the liquid ejection head so that liquid is ejected from the nozzle is different from the state selection signal in a second period for controlling the liquid ejection head so that liquid is not ejected from the nozzle.

[0127] According to this liquid ejection device, the state selection signal during a first period in which the liquid ejection head control circuit controls the liquid ejection head so that liquid is ejected from the nozzle is different from the state selection signal during a second period in which the liquid ejection head control circuit controls the liquid ejection head so that liquid is not ejected from the nozzle, thereby reducing the risk of the state of the switching circuit switching at an unintended timing, and as a result, reducing the risk of malfunction of the liquid ejection device. [Explanation of symbols]

[0128] 1...liquid ejection device, 2...ink container, 10...control mechanism, 20...carriage, 21...liquid Discharge head, 30...movement mechanism, 31...carriage motor, 32...endless belt, 40...transport mechanism, 41...transport motor, 42...transport roller, 50...drive circuit, 51...drive signal output circuit, 52...reference voltage signal output circuit, 60...piezoelectric element, 90...linear encoder, 100...control circuit, 200...drive signal selection circuit, 210, 210a, 210b...selection control circuit, 222a...first register, 222b...second register, 224a...first latch circuit, 224b...second latch switch circuit, 226...decoder, 230...selection circuit, 232a, 232b...inverters, 234a, 234b...transfer gates, 250...memory circuit, 260...control logic circuit, 261...SP register group, 262...selection control signal generating unit, 270...selection signal output unit, 600...ejection unit, 601...piezoelectric body, 611, 612...electrodes, 621...diaphragm, 631...cavity, 632...nozzle plate, 641...reservoir, 651...nozzle, 661...supply port, P...medium

Claims

1. A liquid ejection head control circuit for controlling a liquid ejection head having a drive element that is driven based on a drive signal to eject liquid from a nozzle, and a switching circuit that switches whether or not the drive signal is supplied to the drive element, A drive signal output circuit that outputs the drive signal; A switching control circuit for controlling the switching circuit; Equipped with The switching control circuit includes: a periodic timing signal that defines a dot formation period for forming dots on a medium by liquid ejected from the nozzles; and a discharge control signal that defines the amount of liquid discharged from the nozzle; A switching timing signal that defines a switching timing of the switching circuit; a state selection signal that defines a relationship between a state of the switching circuit and the ejection control signal during a control period defined by the switching timing signal; and the state selection signal in a first period for controlling the liquid ejection head so that liquid is ejected from the nozzle in the dot formation cycle is different from the state selection signal in a second period for controlling the liquid ejection head so that liquid is not ejected from the nozzle in the dot formation cycle; A liquid ejection head control circuit comprising:

2. the state selection signal includes n-bit first data and n-bit second data; the switching control circuit outputs the state selection signal in which the first data and the second data are the same during the second period.

2. The liquid ejection head control circuit according to claim 1,

3. The logic levels of the n bits of the first data are all the same during the second period.

3. The liquid ejection head control circuit according to claim 2.

4. the switching timing signal specifies a switching timing as to whether the switching circuit performs switching as to whether or not to supply the drive signal to the drive element based on the first data, or whether or not to supply the drive signal to the drive element based on the second data.

4. The liquid ejection head control circuit according to claim 2, wherein the liquid ejection head control circuit is a control circuit for controlling a liquid ejection head.

5. the liquid ejection head has a memory circuit in which information relating to the liquid ejection head is stored; The switching control circuit includes: during the first period, controlling the ejection of liquid from the liquid ejection head using at least one of the cycle timing signal, the ejection control signal, the switching timing signal, and the state selection signal; during the second period, storing the information in the memory circuit and reading out the information from the memory circuit are controlled using at least one of the cycle timing signal, the ejection control signal, the switching timing signal, and the state selection signal; 5. The liquid ejection head control circuit according to claim 1, wherein the liquid ejection head control circuit is a control circuit for controlling a liquid ejection head.

6. a liquid ejection head including a drive element that is driven based on a drive signal to eject liquid from a nozzle, and a switching circuit that switches whether or not the drive signal is supplied to the drive element; a liquid ejection head control circuit for controlling the liquid ejection head; Equipped with The liquid ejection head control circuit includes: A drive signal output circuit that outputs the drive signal; A switching control circuit for controlling the switching circuit; Equipped with The switching control circuit includes: a periodic timing signal that defines a dot formation period in which dots are formed on a medium by the liquid ejected from the nozzles; and a discharge control signal that defines the amount of liquid discharged from the nozzle; A switching timing signal that defines a switching timing of the switching circuit; a state selection signal that defines a relationship between a state of the switching circuit and the ejection control signal during a control period defined by the switching timing signal; and the state selection signal in a first period for controlling the liquid ejection head so that liquid is ejected from the nozzle in the dot formation cycle is different from the state selection signal in a second period for controlling the liquid ejection head so that liquid is not ejected from the nozzle in the dot formation cycle; A liquid ejection device comprising:

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