Liquid dispensing head and liquid dispensing device

Abstract

Drive the circulating drive element at the optimal drive frequency. [Solution] The system comprises a discharge module having a discharge drive element and a discharge heater electrically connectable to the discharge drive element, a circulation module having a circulation drive element and a circulation heater electrically connectable to the circulation drive element, and a controller that controls the discharge drive element and the circulation drive element to either a conductive state or a non-conductive state, wherein the controller sets the discharge drive frequency used to drive the discharge drive element and the circulation drive frequency used to drive the circulation drive element to be different.

Description

Technical Field

[0001] The present disclosure relates to a liquid ejection head and a liquid ejection device that perform ejection while circulating a liquid.

Background Art

[0002] Conventionally, among circulation-type liquid ejection devices that circulate a liquid (also referred to as ink), an ink in a circulation flow path communicating with a discharge port is circulated by a circulation driving element different from a discharge driving element that discharges the ink by a circulation driving element. Further, Patent Document 1 discloses a technique for selectively driving a discharge driving element and a circulation driving element.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the technique of Patent Document 1 can only drive the discharge driving element and the circulation driving element at the same driving frequency, so there are cases where the circulation driving element cannot be driven at the driving frequency optimal for the circulation driving element.

Means for Solving the Problems

[0005] A liquid discharge head according to one aspect of the present disclosure comprises: a discharge module having a discharge drive element and a discharge heater electrically connectable to the discharge drive element; a circulation module arranged in pair with the discharge module and having a circulation drive element and a circulation heater electrically connectable to the circulation drive element; and control means for controlling the discharge drive element and the circulation drive element, respectively, to either a conductive state or a non-conductive state, wherein the control means is characterized by making the discharge drive frequency used to drive the discharge drive element and the circulation drive frequency used to drive the circulation drive element different. [Effects of the Invention]

[0006] According to this disclosure, it is possible to drive the circulating drive element at an optimal drive frequency. [Brief explanation of the drawing]

[0007] [Figure 1] This figure shows an example of the overall configuration of a liquid dispensing device. [Figure 2] This figure shows an example of the basic configuration of a liquid dispensing head. [Figure 3] This figure shows an example of the circuit configuration of the ejection element substrate for the first use case. [Figure 4] This figure shows an example of the circuit configuration of a circulating group control circuit. [Figure 5] Figure 3 shows the timing chart for the ejection element substrate. [Figure 6] This figure shows an example of the circuit configuration of the ejection element substrate for the second use case. [Figure 7] Figure 6 shows the timing chart for the ejection element substrate. [Figure 8] This is a plan view of the ejection element substrate. [Figure 9] This is a plan view of the ejection element substrate. [Figure 10] This is a plan view of the ejection element substrate. [Figure 11] This is a plan view of the ejection element substrate. [Best Mode for Carrying Out the Invention]

[0008] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings. Note that the following embodiments are not limiting to the scope of this disclosure, and not all combinations of features described in the following embodiments are essential to the solutions of this disclosure. The same reference numerals are used for identical components.

[0009] (overview) Conventionally, circulating liquid dispensing devices that circulate ink are known. This liquid dispensing device has a liquid dispensing head. The ink is circulated for the purpose of discharging air bubbles in the flow path of the liquid dispensing head and suppressing the viscosity increase of the ink near the outlet. For example, a method using a pressure difference (hereinafter also referred to as the "differential pressure method") is a well known method for circulating ink. In the differential pressure method, by using a pressure adjustment mechanism, the pressure on the side supplying ink to the outlet (also referred to as the in side) is set higher than that on the side from which the ink is recovered (also referred to as the out side). By setting such a pressure difference, ink can flow from the in side to the out side. Here, in order to circulate the ink, it is necessary to return the ink that has flowed to the out side to the in side. For this reason, a pump is required as a mechanism. In some cases, the pump is installed outside the head of the liquid dispensing device body to circulate the ink between the liquid dispensing head and the liquid dispensing device body. Alternatively, in some cases, the pump is installed inside the liquid dispensing head to circulate the ink within the liquid dispensing head. However, such differential pressure circulation methods require mechanisms such as a pressure adjustment mechanism and a pump. Therefore, the liquid dispensing device body and liquid dispensing head tend to be larger.

[0010] Therefore, as an alternative method to the differential pressure method for circulating ink, the following method exists: In some cases, a circulation drive element separate from the ejection drive element for ejecting ink is placed in the circulation channel that communicates with the ejection port. Mechanisms are known in which the ink in the circulation channel is circulated by driving the circulation drive element with such an arrangement.

[0011] Furthermore, a circuit configuration for selectively driving each of the multiple ejection drive elements and multiple circulation drive elements provided on the ejection element substrate included in the liquid ejection head is also disclosed. In such a circuit configuration, the function of selectively driving each of the multiple ejection drive elements and multiple circulation drive elements is realized by assigning an address to each of the multiple ejection drive elements and multiple circulation drive elements. Therefore, as the number of ejection drive elements and multiple circulation drive elements increases, the amount of data transferred for the data signals that specify the addresses individually increases. As the amount of data transferred increases, the number of circuits that deal with problems such as data signal crosstalk increases, so it is preferable not to increase the amount of data transferred. Therefore, in order to reduce the amount of data transferred, a configuration can be considered in which the selection information of the circulation drive elements is converted within the ejection element substrate according to the selection information of the ejection drive elements, and each circulation drive element is selected. With such a configuration, it is possible to reduce the amount of data transferred. However, even with such a configuration, each of the ejection drive elements and the circulation drive elements is selected by a data signal with the same drive frequency. In the first place, the optimal timing for ejecting ink and the optimal timing for circulating ink are different. Therefore, even if the same drive frequency is optimal for the discharge drive element, it may not be optimal for the circulation drive element. Accordingly, in this disclosure, at least the discharge drive frequency used to drive the discharge drive element and the circulation drive frequency used to drive the circulation drive element are made different. By doing so, the circulation drive frequency can be set at a different drive frequency than the discharge drive frequency, making it possible to drive the circulation drive element at an optimal drive frequency.

[0012] <Liquid discharge device 50> Figure 1 shows an example of the overall configuration of the liquid dispensing device 50. Figure 1(a) is a schematic perspective view showing the liquid dispensing device 50 in which a main ink tank 2 is provided as a liquid storage unit outside the liquid dispensing head 1. Figure 1(b) is a schematic perspective view showing the liquid dispensing device 50 in which an ink sub-tank 54 is provided directly above the liquid dispensing head 1. First, the common parts of Figure 1(a) and Figure 1(b) will be explained.

[0013] The liquid ejection device 50 comprises a liquid ejection head 1 and transport rollers 55, 56, 57, and 58. The liquid ejection head 1 is scannable in a direction X intersecting the transport direction Y of the ejection medium P. The liquid ejection head 1 is mounted on a carriage 60. The carriage 60 reciprocates along a guide axis 51 in the main scanning direction (also referred to as direction X). The transport rollers 55, 56, 57, and 58 transport the ejection medium P in a secondary scanning direction (also referred to as transport direction Y) that intersects (orthogonal in this embodiment) the main scanning direction. That is, the liquid ejection device 50 constitutes a serial-type inkjet liquid ejection device by scanning the liquid ejection head 1 in direction X and ejecting liquid from the liquid ejection head 1 onto the ejection medium P being transported in the transport direction Y. Note that the application of this disclosure is not limited to a serial-type inkjet liquid ejection device. This disclosure is also applicable to page-wide inkjet liquid ejection devices that eject liquid onto a medium P being transported in the transport direction Y by using a line head (page-wide type head) that is long in the page width direction of the ejection medium P. In Figures 1(a) and 1(b), direction Z indicates the vertical direction. That is, direction Z is the direction that intersects (orthogonal in this embodiment) the XY plane specified by direction X and transport direction Y.

[0014] The liquid ejection head 1 can eject four types of inks: black (K), cyan (C), magenta (M), and yellow (Y). The liquid ejection head 1 can eject a full-color image using these four types of inks. Note that the inks that can be ejected from the liquid ejection head 1 are not limited to the above four types. For example, the present disclosure is also applicable to the liquid ejection head 1 for ejecting other types of inks, such as special inks. That is, the type and number of inks ejected from the liquid ejection head 1 are not limited.

[0015] Next, the different parts of FIGS. 1(a) and 1(b) will be described. In FIG. 1(a), an ink sub-tank 54 is mounted on the liquid ejection head 1. Four ink supply tubes (liquid communication passages) 59 are attached to the ink sub-tank 54. Further, the liquid ejection device 50 includes an ink tank 2 and an external pump 21. The ink tank 2 stores ink. The ink stored in the ink tank 2 is supplied to the ink sub-tank 54 through the four ink supply tubes 59 by the driving force of the external pump 21. On the other hand, in FIG. 1(b), the ink sub-tank 54 is provided directly above the liquid ejection head 1. In FIG. 1(b), the difference from FIG. 1(a) is that since the ink tank 2 is not provided outside the liquid ejection head 1, the four ink supply tubes 59 are not attached, and the external pump 21 is not provided. In both FIGS. 1(a) and 1(b), the liquid ejection head 1 may be integrally provided with the ink sub-tank 54 and configured to be removable or attachable to the carriage 60. Alternatively, the ink sub-tank 54 may be integrally provided with the carriage 60, and only the ink sub-tank 54 may be configured to be removable or attachable. In the following description, the configuration of FIG. 1(a) will be used for the explanation.

[0016] <Liquid ejection head 1> FIG. 2 is a diagram showing a basic configuration example of the liquid ejection head 1 in FIG. 1. FIG. 2(a) is an exploded perspective view of the liquid ejection head 1 in FIG. 1. FIGS. 2(b), 2(c), and 2(d) are overall views of the ejection element substrate 101 in FIG. 2(a). The liquid ejection head 1 includes a housing portion 53, an ink sub-tank 54, and an ejection element unit 100. The ink sub-tank 54 is housed in the housing portion 53. The ejection element unit 100 is provided at the bottom of the housing portion 53. Although not shown, four joints are provided on the wall surface of the housing portion 53, each of which is connected to each of the four ink supply tubes 59 corresponding to the four types of inks. That is, individual ink supply paths are provided for each type of ink.

[0017] The ejection element unit 100 includes a first support member 505, a second support member 503, an ejection element substrate 101, and an electrical wiring member 501. An ink supply port and an ink recovery port are provided in the first support member 505. An opening is provided in the second support member 503. The ejection element substrate 101 is adhesively fixed to the first support member 505. The first support member 505 is adhesively fixed to the second support member 503. The second support member 503 holds the electrical wiring member 501 so that it is electrically connected to the ejection element substrate 101. The electrical wiring member 501 applies an electrical signal for ejecting ink and an electrical signal for circulating ink to the ejection element substrate 101. Details of the electrical signal for ejecting ink and the electrical signal for circulating ink will be described later.

[0018] Figure 2(b) shows an example in which one ejection element substrate 101 is configured for every four colors. The four colors are, for example, black, cyan, magenta, and yellow, and each color is in a separate row. Each row is configured along the transport direction Y and spaced apart along the direction X. Multiple ejection ports in each row are spaced equally along the Y direction. Alternatively, the ejection ports in each row may be arranged in a single row along the Y direction without spacing in the X direction. Alternatively, black may be arranged in two rows, resulting in a total of five rows for the four colors. Figure 2(c) shows an example in which one ejection element substrate 101 is configured for every two colors. Two ejection element substrates 101 may be mounted on one liquid ejection head 1. Alternatively, two liquid ejection heads 1, each mounted on one ejection element substrate 101, may be prepared. Figure 2(d) shows an example in which one ejection element substrate 101 is configured for every one color. Four ejection element substrates 101 may be mounted on a single liquid ejection head 1. Alternatively, four liquid ejection heads 1, each mounted on a single ejection element substrate 101, may be prepared. Note that, as shown in Figures 2(c) and 2(d), if the ejection element substrate 101 is divided into multiple parts, they do not all need to be the same length. Furthermore, various combinations of other colors are possible for the ejection element substrate 101, and the same applies when the total number of colors exceeds four. The details of the electrical signals for ejecting ink and the electrical signals for circulating ink will be explained below, referring to various use cases such as circuit configurations.

[0019] (First use case) Figure 3 shows an example of the circuit configuration of the ejection element board 101 for the first use case. Various signals are supplied to the ejection element board 101 from the main board 201. The main board 201 includes a controller 202 and a power supply circuit 203. The controller 202 is mainly composed of ROM, RAM, and CPU, and controls the liquid ejection head 1 by supplying various electrical signals to the ejection element board 101. The controller 202 supplies the enable signal HE, latch signal LT, data signal DATA, and clock signal CLK to the ejection element board 101. Details of each signal will be described later. The power supply circuit 203 applies a power supply voltage VH to the ejection element board 101. The power supply circuit 203 and the ejection element board 101 are connected by GNDH. GNDH functions as the ground potential.

[0020] (Wiring Overview) The ejection element substrate 101 comprises a plurality of ejection modules 11, a plurality of circulation modules 12, and a control data supply circuit 31. The circulation modules 12 are arranged in pairs with the ejection modules 11. Therefore, the number of circulation modules 12 is the same as the number of ejection modules 11. Between the plurality of ejection modules 11 and the control data supply circuit 31, ejection group selection signal wiring 19, circulation group selection signal wiring 20, ejection time-division selection signal wiring 18, and circulation time-division selection signal wiring 33 are wired. Between the plurality of circulation modules 12 and the control data supply circuit 31, ejection group selection signal wiring 19, circulation group selection signal wiring 20, ejection time-division selection signal wiring 18, and circulation time-division selection signal wiring 33 are also wired.

[0021] (Discharge module 11) The discharge module 11 includes a discharge heater RhA, a discharge driver element MD1, and a discharge logic circuit AND1. The discharge heater RhA is composed of, for example, an electrothermal conversion element. A voltage from the power supply voltage VH is applied to the discharge heater RhA, and if the discharge driver element MD1 is in a conductive state, current flows through the discharge heater RhA. The discharge driver element MD1 is composed of, for example, a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). However, the discharge driver element MD1 may be composed of something other than a MOSFET. For example, the discharge driver element MD1 may be composed of a bipolar transistor. Alternatively, the discharge driver element MD1 may be composed of an IGBT (Insulated Gate Bipolar Transistor). The discharge logic circuit AND1 selectively drives the discharge driver element MD1. An enable signal HE, a discharge group selection signal, and a discharge time-division selection signal are input to the input side of the discharge logic circuit AND1. The enable signal HE is transmitted from the controller 202. The enable signal HE controls the current pulse width of the discharge drive element MD1, that is, the duration for which the drain-source of the discharge drive element MD1 is conductive and current continues to flow between the drain-source of the discharge drive element MD1. The enable signal HE is a signal for adjusting the current pulse width so that more desired thermal energy can be generated, taking into account various manufacturing variations. Examples of various manufacturing variations include manufacturing variations in the resistance value of the discharge heater RhA mounted on the discharge element substrate 101 and manufacturing variations in the power supply circuit 203. Other examples of various manufacturing variations include the voltage drop in the power supply wiring when multiple heaters, such as the discharge heater RhA and the circulation heater RhB, are driven simultaneously. The heaters targeted for simultaneous drive here are the discharge heater RhA and the circulation heater RhB, which is located in a position not paired with the discharge heater RhA. The enable signal HE can be transmitted from the controller 202 via an external input terminal (not shown) provided on the ejection element board 101. The ejection group selection signal is supplied from the ejection group selection signal wiring 19.The ejection time-division selection signal is supplied from the ejection time-division selection signal wiring 18. The output side of the ejection logic circuit AND1 is connected to the gate of the ejection drive element MD1. Therefore, if all signals input from the input side of the ejection logic circuit AND1 are 1, a voltage is applied to the gate of the ejection drive element MD1, and the drain-source of the ejection drive element MD1 becomes conductive. When the drain-source of the ejection drive element MD1 is conductive, current flows through the ejection heater RhA, generating heat in the ejection heater RhA. This series of operations makes it possible for the ink to foam before being ejected and then ejected onto the ejection medium P. Although an example of the ejection heater RhA being composed of an electrothermal conversion element has been described, it is not limited to this. For example, the ejection heater RhA may be composed of a piezoelectric element.

[0022] (Circulation module 12) The circulating module 12 includes a circulating heater RhB, a circulating drive element MD2, and a circulating logic circuit AND2. The circulating heater RhB is composed of, for example, an electrothermal conversion element. A voltage from the power supply voltage VH is applied to the circulating heater RhB, and if the circulating drive element MD2 is in a conductive state, current flows through the circulating heater RhB. The circulating drive element MD2 is composed of, for example, a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). However, the circulating drive element MD2 may be composed of something other than a MOSFET. For example, the circulating drive element MD2 may be composed of a bipolar transistor. Alternatively, the circulating drive element MD2 may be composed of an IGBT (Insulated Gate Bipolar Transistor). The circulating logic circuit AND2 selectively drives the circulating drive element MD2. An enable signal HE, a circulating group selection signal, and a circulating time division selection signal are input to the input side of the circulating logic circuit AND2. The enable signal HE is transmitted from the controller 202. The enable signal HE controls the current pulse width of the circulating drive element MD2, that is, the time for which the drain-source of the circulating drive element MD2 is conductive and current continues to flow between the drain-source of the circulating drive element MD2. The enable signal HE is a signal for adjusting the current pulse width so that more desired thermal energy can be generated, taking into account various manufacturing variations. Examples of various manufacturing variations include manufacturing variations in the resistance value of the circulating heater RhB mounted on the discharge element substrate 101 and manufacturing variations in the power supply circuit 203. Other examples of various manufacturing variations include the voltage drop in the power supply wiring when multiple heaters, such as the circulating heater RhB and the discharge heater RhA, are driven simultaneously. The enable signal HE can be transmitted from the controller 202 via an external input terminal (not shown) provided on the discharge element substrate 101. The circulating group selection signal is supplied from the circulating group selection signal wiring 20. The time-division selection signal for the cycle is supplied from the time-division selection signal wiring 33 for the cycle. The output side of the cycle logic circuit AND2 is connected to the gate of the cycle drive element MD2.Therefore, if all signals input from the input side of the circulating logic circuit AND2 are 1, a voltage is applied to the gate of the circulating drive element MD2, and the drain-source of the circulating drive element MD2 becomes conductive. When the drain-source of the circulating drive element MD2 is conductive, current flows through the circulating heater RhB, generating heat in the circulating heater RhB. This series of operations allows ink bubbles to grow and enables the generation of circulating flow in the ink circulation channel. Although an example of the circulating heater RhB being composed of an electrothermal conversion element has been described, it is not limited to this. For example, the circulating heater RhB may be composed of a piezoelectric element.

[0023] Furthermore, in order to reduce the number of signal terminals, the above-mentioned enable signal HE is shared by both the ejection and circulation heaters. Therefore, the current pulse width cannot be controlled individually for the ejection and circulation heaters. Thus, assuming that the ejection heater RhA and the circulation heater RhB are manufactured in the same process of the semiconductor manufacturing process and finished with the same manufacturing variation (amount of resistance deviation from the ideal value), the current pulse width may be adjusted with a single enable signal HE.

[0024] (Control data supply circuit 31) The control data supply circuit 31 includes shift registers 13a, 13b, and 13c, latch circuits 14a, 14b, and 14c, a cyclic decoder circuit 32, a decoder circuit 15, and a cyclic group control circuit 16. The control data supply circuit 31 is also provided with an external input terminal. The control data supply circuit 31 receives a clock signal CLK, a data signal DATA, and a latch signal LT from the controller 202 via the external input terminal. The clock signal CLK is used when serially transferring the data signal DATA to the shift registers 13c, 13a, and 13b. The data signal DATA includes selection information for the output module 11 and selection information for the cyclic module 12. The latch signal LT acquires and holds the information stored in each of the shift registers 13c, 13a, and 13b at each latch cycle. Details of the cyclic decoder circuit 32, decoder circuit 15, and cyclic group control circuit 16 will be described later.

[0025] (Drive control of the discharge heater RhA) This section describes the drive control of ejector heaters RhA based on ejector heater array 21. The ejector heater array 21 consists of m groups. Each group contains n ejector heaters RhA. The ejector heaters RhA are positioned directly below the ink ejection port. When one group is selected, each of the n ejector heaters RhA within that group is operated sequentially in a time-division multiplexing manner. The ejector heater array is arranged in a 1-inch length at an array density of 600 dpi, and the drive control of (n=16) × (m=40 groups) of ejector heaters RhA is described.

[0026] (Time-division control within a single group) As described above, each ejection module 11 contains an ejection heater RhA. Furthermore, one group contains n ejection heaters RhA. Therefore, one group contains n ejection modules 11. Since we are assuming n=16, the 16 ejection modules 11 are time-division driven by the ejection time-division selection signal. Time-division driving is a control method that divides the time of a certain ejection cycle into n=16 time units, and sequentially selects one ejection module 11 for each divided time unit. Here, within the same group, multiple ejection modules 11 are never selected simultaneously. All ejection modules 11 included in the same group are always selected exactly once within one ejection cycle. In this time-division driving, only one of the ejection time-division selection signal wirings 18 is selected. Therefore, by including the decoder circuit 15 in the control data supply circuit 31, the amount of data transferred serially from the main board 201 can be further reduced.

[0027] (Decoder circuit 15; time-division control) The decoder circuit 15 is a circuit that expands the number of bits in the output data to 2 to the power of q, where q is the number of bits in the input data. Specifically, if 4 bits of input data are input to the decoder circuit 15, the decoder circuit 15 converts the 4 bits of input data into 2 to the power of 4 = 16 bits of output data. At this time, the output data from the decoder circuit 15 is output as information in which only 1 bit of the 16 bits is valid. This enables time-division multiplexing. Here, the output time-division multiplexing selection signal wiring 18 for output from the decoder circuit 15 is preferable to use all wiring as output time-division multiplexing selection signals in terms of input data utilization efficiency, unless there is a special application. Note that if the amount of data in serial transfer increases, faster serial transfer is required. Therefore, it is preferable to reduce the amount of data as much as possible, as this will increase the cost and size of the signal transmission circuit, signal reception circuit and transmission line on the main board 201 and the output element board 101.

[0028] (Group selection control) To select and drive one of the m groups, an m-bit ejection group selection signal is output from the control data supply circuit 31. When selecting one of the m groups, it is possible to simultaneously select n ejection modules 11 included in that group. Information equivalent to the number of groups, m bits, is serially transferred from the main board 201. As described above, the ejection module 11 is selected and controlled so that current flows to the corresponding ejection heater RhA when the enable signal HE, the ejection group selection signal, and the ejection time division selection signal are input to the ejection logic circuit AND1. In this embodiment, an example is described assuming n=16 and m=40, but it is not limited to these. For example, n=8 and m=80 may also be used. Alternatively, for example, a different nozzle length n=32 and m=40 may be used. However, since n is the time division number, it is preferable that n be a value expressed as a power of 2 (n=2, 4, 8, 16, 32...) in order to use the output signal of the decoder circuit 15 as the selection signal.

[0029] (Drive control of circulation module 12) This section describes the drive control of the circulating heaters RhB based on the circulating heater array 22. The circulating heater array 22, like the discharge heater array 21, consists of m groups. Each group contains n circulating heaters RhB, similar to the discharge heater array 21. The circulating heaters RhB are arranged in close proximity to the discharge heaters RhA in pairs. When one group is selected, each of the n circulating heaters RhB within that group is executed sequentially in a time-division multiplexer. This section describes the drive control of circulating heaters RhB for (n=16) × (m=40 groups).

[0030] (Time-division control within a single group) As described above, the circulating heater RhB is included in each circulating module 12. Also, one group contains n circulating heaters RhB. Therefore, one group contains n circulating modules 12. Furthermore, assuming n=16, the 16 circulating modules 12 are time-division driven by the circulating time-division selection signal with a different number of time divisions than the discharge module 11. In this embodiment, the number of time divisions for the circulating module 12 is 32, which is twice the number of time divisions for the discharge module 11, n=16. To reduce the amount of data transmitted serially from the main board 201, the control data supply circuit 31 includes a circulating decoder circuit 32 for the circulating time-division selection signal.

[0031] (Circular decoder circuit 32; time-division control) The cyclic decoder circuit 32 is a circuit that expands the number of bits in the output data to 2 to the power of q, where q is the number of bits in the input data. Specifically, if 5 bits of input data are input to the cyclic decoder circuit 32, the cyclic decoder circuit 32 converts the 5 bits of input data into 2 to the power of 5 = 32 bits of output data. At this time, the output data of the cyclic decoder circuit 32 is output as information in which only 1 bit of the 32 bits is valid. This enables time-division multiplexing. Here, the cyclic heater RhB is composed of (n=16) × (m=40 groups). Therefore, of the cyclic time-division multiplexing selection signal with 32 bits of output data, half of the 16 bits are used as the selection signal for the cyclic module 12, and the remaining 16 bits are not connected to any circuit and remain unused. In other words, of the 32 bits, half of the 16 bits are used for time division, and the remaining 16 bits are used as delay slots instead of time division. Furthermore, while the ejection module 11 is running in time-division mode for one cycle, the circulation module 12 is also running in time-division mode. However, while the ejection module 11 is running in time-division mode for two cycles, the circulation module 12 is not selected. As a result, while the circulation module 12 is running in time-division mode for one cycle, the ejection module 11 is running in time-division mode for two cycles. In the example above, 16 bits of the 32 bits are used for time-division mode and the remaining 16 bits are used for delay slots, but this is not the only example. For example, 20 bits of the 32 bits may be used for time-division mode and the remaining 12 bits may be used for delay slots. In short, the ejection operating frequency and the circulation drive frequency should be different. Specifically, the number of time divisions of the circulation time-division selection signal should be set to be greater than the number of time divisions of the ejection time-division selection signal. As an example, the first use case describes the process of lowering the circulation drive frequency compared to the ejection drive frequency.

[0032] (Group selection control) To select and drive one of the m groups, an m-bit cyclic group selection signal is output from the control data supply circuit 31. When selecting one of the m groups, it is possible to simultaneously select n cyclic modules 12 included in that group. Information equivalent to the number of groups, m bits, is serially transferred from the main board 201. As described above, the cyclic module 12 is selected and controlled so that current flows to the corresponding cyclic heater RhB when the enable signal HE, the cyclic group selection signal, and the cyclic time-division selection signal are input to the cyclic logic circuit AND2. However, the cyclic group selection signal is transferred from the cyclic group control circuit 16 via the cyclic group selection signal wiring 20. The cyclic group control circuit 16 is included in the control data supply circuit 31.

[0033] (Circulation group control circuit 16) The circulating group control circuit 16 generates a circulating group selection signal according to the selection information of the discharge group selection signal. Figure 4 shows an example of the circuit configuration of the circulating group control circuit 16 shown in Figure 3. The circulating group control circuit 16 includes a NOT circuit and an AND circuit. The result of the logical AND of the signal obtained by logically inverting the discharge group selection signal obtained from the discharge group selection signal wiring 19 using the NOT circuit and the circulating flag signal obtained from the circulating flag signal wiring 17 is processed as follows. That is, the result of the logical AND is output to the circulating group selection signal wiring 20 as a circulating group selection signal. Therefore, when the discharge module 11 is in a selected state, the circulating module 12 is in a deselected state. On the other hand, when the discharge module 11 is in a deselected state and the circulating flag signal is High, the circulating module 12 is in a selected state. That is, the pair of discharge modules 11 and circulating module 12 are selected mutually exclusive of each other. Note that while time-division selection is not performed, neither the discharge module 11 nor the circulating module 12 is selected.

[0034] (Timing chart) Figure 5 is the timing chart for the ejection element board 101 in Figure 3. The clock signal CLK, data signal DATA, latch signal LT, and enable signal HE are input to the ejection element board 101 from the main board 201. For each latch period, the ejection time division selection signal is divided into 1 to 16 time divisions, thereby sequentially driving the ejection drive element MD1 and allowing current to flow to the corresponding ejection heater RhA. Similarly, for each latch period, the cyclic time division selection signal is divided into 1 to 32 time divisions, thereby sequentially driving the cyclic drive element MD2. As described above, 16 bits of the cyclic time division selection signal are used as the selection signal for the cyclic module 112, so as shown in Figure 5, current flows to the corresponding cyclic heater RhB during time division units 1 to 16. However, for the remaining 16 unused bits of the cyclic time division selection signal, which are time division units 17 to 32, the corresponding cyclic heater RhB is not selected. That is, it is assumed that the ejection operation is performed at an ejection frequency of, for example, 30 kHz while the time-division drive of the ejection heater array 21 completes one cycle over the ejection period. According to this assumption, since the number of time divisions of the circulation heater array 22 is set to twice that of the ejection heater array 21, ink circulation operation can be performed at 15 kHz, which is half the ejection frequency. In this embodiment, it is assumed that 1 to 16 of the circulation time-division selection signals are used, but other combinations are also possible. For example, even bits may be used and odd bits may not be used. Furthermore, by setting the number of time divisions of the circulation heater array 22 to four times, eight times, or more times that of the ejection heater array 21, the ink circulation operation may be set to one-quarter, one-eighth, or even half of the ejection frequency. The optimal frequency band for the ejection drive frequency and the ink circulation operation may differ depending on the circumstances. As in this embodiment, by using the circulation time-division selection signal for the circulation heater array 22, it becomes possible to drive the circulation heater array 22 to an optimal drive frequency for ink circulation operation, regardless of the drive frequency of the ejection heater array 21. In addition, this embodiment further provides a circulation flag signal to determine whether the circulation group selection signal can be enabled. By disabling the circulation flag signal, the selection of the circulation module 12 is prohibited during normal ejection operation that does not require ink circulation. It is preferable to transmit the circulation flag signal serially from the main board 201.

[0035] In this embodiment, the discharge module 11 and the circulation module 12 are each connected to a common power supply voltage VH (e.g., 24V) and a common ground potential GNDH. However, if it is desired to further mitigate fluctuations in discharge energy due to voltage drops when driving the discharge heater RhA and the circulation heater RhB, the following measures can be taken. Specifically, separate power supply voltage and ground potential supply wiring and external connection terminals may be provided for the discharge module 11 and the circulation module 12 within the discharge element board 101. In other words, they may be supplied individually from the power supply circuit 203 mounted on the main board 201.

[0036] Generally, since drive elements operate at a higher voltage than logic circuits, a substrate is used in which high-voltage drive elements and normal drive elements coexist. In this embodiment, the ejection drive element MD1 and the circulation drive element MD2 may be composed of high-voltage MOS transistors, specifically DMOS transistors (Double-diffused MOSFETs). The ejection logic circuit AND1, the circulation logic circuit AND2, the circulation group selection circuit 16, and other logic circuits such as shift registers 13a, 13b, 13c, latch circuits 14a, 14b, 14c, and decoder circuit 15 may be composed of low-voltage MOS transistors.

[0037] (Second use case) Figure 6 shows an example of the circuit configuration of the ejection element substrate 102 for the second use case. In the second use case, the explanation of the same configuration and functions as in the first use case will be omitted. The second use case differs from the first use case in the following respects. Specifically, the cyclic decoder circuit 32, latch circuit 14c, and shift register 13c are removed from the control data supply circuit 41, and an ejection period counter circuit 42 is newly added, and a time-division frequency divider signal wiring is added accordingly, which is the difference from the first use case.

[0038] The control data supply circuit 41 includes a discharge cycle counter circuit 42. The discharge cycle counter circuit 42 is composed of, for example, a toggle circuit using a flip-flop. The discharge cycle counter circuit 42 acquires the discharge time-division selection signal from the discharge time-division selection signal wiring 18. For each cycle of time-division drive of the discharge heater RhA, the discharge cycle counter circuit 42 outputs a signal to the time-division frequency divider signal wiring 43, which repeatedly generates "High" and "Low" alternately from the output logic of the acquired discharge time-division selection signal. The logical AND of the time-division frequency divider signal wiring 43 and the discharge time-division selection signal wiring 18 is input to the cyclic logic circuit AND2. As a result, every other cycle of time-division drive of the discharge heater RhA, the output logic of the cyclic logic circuit AND2 is set to "Low", and the cyclic drive element MD2 becomes non-conductive. Therefore, every other cycle of time-division drive of the discharge heater RhA, no current flows to the cyclic heater RhB. In other words, just like in Use Case 1, the time-division drive of the discharge module 11 completes two cycles while the time-division drive of the circulation module 12 completes one cycle.

[0039] (Timing chart) Figure 7 is a timing chart of the ejection element substrate shown in Figure 6. The clock signal CLK, data signal DATA, latch signal LT, and enable signal HE are input to the ejection element substrate 101 from the main substrate 201. The ejection time division selection signal is divided into 16 segments from 1 to 16 for each latch period, thereby sequentially driving the ejection drive element MD1 and causing current to flow to the corresponding ejection heater RhA. In this embodiment, each time the falling edge of the 16th time division of the ejection time division selection signal is input to the ejection period counter circuit 42, the logic of the time division frequency divide signal, which is the output signal, repeatedly outputs "High" and "Low". Note that the ejection time division selection signal may be selected in any order from 1 to 16. As described above, when the time division frequency divide signal is "High", the ejection time division selection signal is active in the circulation module 12, and as shown in Figure 7, current flows to the corresponding circulation heater RhB during the time units 1 to 16 of the ejection time division. However, since the time division frequency divider signal is in "Low" logic during the time units 1 to 16 of the next cycle's ejection time division, the corresponding circulating heater RhB is not selected. Therefore, compared to the first use case, it is possible to achieve the same effect as the first use case, namely, ink circulation operation at half the ejection frequency, while suppressing the increase in circuit and wiring area. Furthermore, by changing the period for switching the output logic of the time division frequency divider signal to every 4 cycles or every 8 cycles with respect to the ejection time division selection signal, it is also possible to make the ink circulation operation 1 / 4 or 1 / 8 of the ejection frequency. The period for switching the output logic of the time division frequency divider signal may be determined when designing the mask of the ejection element substrate 102, but it may also be configured to be serially transmitted from the main board 201 along with the ejection heater selection information so that it can be freely changed depending on the physical properties of the ink used. Although an example in which the ejection cycle counter circuit 42 is composed of a toggle circuit has been described, it is not limited to this. For example, the ejection cycle counter circuit 42 may be composed of a counter circuit instead of a toggle circuit. With this circuit configuration, for example, it is possible to process the switching period of the output logic of the time-division frequency divider signal to every 3, 4, or 5 cycles relative to the output time-division selection signal. In short, the output operating frequency and the circulating drive frequency must be different.As an example, the second use case describes a process for reducing the cycle period compared to the discharge cycle. For example, one discharge cycle is considered as one unit, and the goal is to reduce the cycle period. Under this assumption, for example, to reduce the cycle period to three cycles, the following operation may be performed: That is, the cycle period may be "High" for the first discharge cycle, "Low" for the second and third discharge cycles, and "High" for the fourth discharge cycle. In short, it is also possible to process the cycle for switching the output logic of the time-division frequency divider signal at predetermined intervals with respect to the discharge time-division selection signal.

[0040] (Third use case) Let's explain the case where the discharge frequency is low. For example, if the discharge frequency is 7.5 kHz and the cyclic operation is driven at 15 kHz, the following configuration may be used. That is, the discharge time division selection signal is set to 32 bits, and of these 32 bits, bits 1 to 16 are used for selecting the discharge heater RhA, and bits 17 to 32 are assumed to be unused. Based on this assumption, the cyclic time division selection signal is set to 16 bits, so that the cyclic time division cycle completes twice while the discharge time division cycle completes once. With this operation, it is possible to double the frequency of the cyclic operation to the discharge frequency.

[0041] In other words, as described above, the same number of ejection modules 11 and circulation modules 12 are provided. Furthermore, the control data supply circuit 31 may set the number of time divisions of the ejection time division selection signal, which drives the ejection drive element MD1 in a time division manner, to more than twice the number of time divisions of the circulation time division selection signal, which drives the circulation drive element MD2 in a time division manner. Note that in the example above, 16 bits of the 32 bits were used for time division and the remaining 16 bits were used for delay slots, but this is not the only example. For example, 20 bits of the 32 bits may be used for time division and the remaining 12 bits may be used for delay slots. In short, the ejection operating frequency and the circulation drive frequency should be different. Specifically, the number of time divisions of the ejection time division selection signal should be set to be greater than the number of time divisions of the circulation time division selection signal. As an example, the third use case describes the process of lowering the ejection drive frequency compared to the circulation drive frequency.

[0042] (Circuit area) The drive current of the circulating heater RhB generates thermal energy to circulate the ink in the individual channels. When the drive current of the circulating heater RhB is smaller than the drive current of the ejection heater RhA that ejects to the ejection medium, the current driving capability of the DMOS transistor can be small. Therefore, since it is not necessary to make the area of ​​the circulating drive element MD2 larger than the area of ​​the ejection drive element MD1, a configuration in which the area of ​​the circulating drive element MD2 is smaller than the area of ​​the ejection drive element MD1 is more preferable.

[0043] (Example 1 of circuit layout) Figure 8 is a plan view of the ejection element substrate 103. In one example of Figure 8, two systems of mechanisms for selective control are arranged from the control data supply circuit 31 to the ejection heater row 21 and the circulation heater row 22, with point symmetry based on the center of the ejection element substrate 103. In Figure 8, in the transport direction Y, three rows of ink supply port arrays 23 are arranged at intervals along the direction X. In Figures 9 to 11 thereafter, the transport direction Y and direction X are defined similarly. That is, direction X is defined in the horizontal direction of the paper, and the transport direction Y is defined in the vertical direction of the paper. Between each ink supply port array 23, one row each of the ejection heater row 21 and the circulation heater row 22 are arranged along the transport direction Y. Of the three rows of ink supply port arrays 23, the left region of the left ink supply port array 23 and the right region of the right ink supply port array 23 are arranged as follows. Specifically, the following are arranged: discharge drive element MD1, circulation drive element MD2, discharge logic circuit AND1, circulation logic circuit AND2, discharge group selection signal wiring 19, circulation group selection signal wiring 20, discharge time division selection signal wiring 18, and circulation time division selection signal wiring 33.

[0044] External connection terminals are arranged along the X direction at two locations, above and below the substrate edge in the transport direction Y of the ejection element substrate 103. A control data supply circuit 131 is located in the area between the external connection terminals and the ink supply port arrangement 23. Since the area between the external connection terminals and the ink supply port arrangement 123 is located at two locations, above and below, in the transport direction Y, the control data supply circuit 131 is also located at two locations, above and below, in the transport direction Y.

[0045] As shown in Figure 8, since the ejection element substrate 103 is configured to be positioned in the transport direction Y, it is possible to reduce the substrate dimensions in the direction X of the ejection element substrate 103. Although not shown in the figure, if the arrangement of the ejection element substrate 103 is considered as one unit, it is also possible to arrange multiple ejection element substrates 103 in the direction X to accommodate multiple ink types within a single ejection element substrate 103.

[0046] (Second example of circuit layout) Figure 9 is a plan view of the ejection element substrate 104. Compared to the ejection element substrate 103 in Figure 8, the ejection element substrate 104 in Figure 9 does not have the time-division selection signal wiring 33 for circulation. Therefore, the control data supply circuit 41 is located at two locations on the left and right ends of the ejection element substrate 104 in direction X. Although the substrate dimensions in direction X are slightly larger compared to the example in Figure 8, the ejection element substrate 104 in Figure 9 can have smaller substrate dimensions in the transport direction Y, and the area of ​​the ejection element substrate can also be smaller than that of Embodiment 1.

[0047] (Third example of circuit layout) Figure 10 is a plan view of the ejection element substrate 105. Compared to the ejection element substrate 104 in Figure 9, the external connection terminals of the ejection element substrate 105 in Figure 10 are positioned on the left side in direction X. Compared to the ejection element substrate 104, it is possible to reduce the substrate dimensions in the transport direction Y. Although not shown in the illustration, the wiring configuration of the ejection element substrate 105 is assumed to be one unit. In this assumption, if multiple ejection element substrates 105 are mounted along the arrangement direction of the ink supply port row 23, this configuration, in which the external connection terminals are not provided on the extension line of the ink supply port row 23, allows for a smaller distance between the ejection element substrates 105. Therefore, it is also possible to reduce the liquid ejection head size.

[0048] (Fourth example of circuit layout) Figure 11 is a plan view of the ejection element substrate 106. In Figure 11, units including the control data supply circuit 41, ink supply port array 23, ejection heater row 21, circulation heater row 22, and ink supply port array 23 are arranged in line in direction X. This arrangement is configured such that the distance between each ink supply port row 23 is increased for each unit, assuming that different types of ink are supplied to the ink supply port array 23 on the ejection element substrate 106. With this configuration, it is possible to avoid mixing of inks of different types during ejection.

[0049] <Other Embodiments> Although various examples and embodiments of this disclosure have been described above, the spirit and scope of this disclosure are not limited to the specific descriptions herein. This disclosure is not limited to the embodiments described above, and various modifications may be made. Furthermore, this disclosure may combine some of the embodiments described above as appropriate.

[0050] (Variation 1) For example, in this embodiment, an example has been described in which the time intervals of the conduction state and non-conduction state of the discharge drive element MD1 and the circulation drive element MD2 are equally divided into time intervals, but the embodiment is not limited to this. For example, the time interval of the conduction state of the discharge drive element MD1 and the circulation drive element MD2 may be different from the time interval of the non-conduction state of the discharge drive element MD1 and the circulation drive element MD2.

[0051] (Modification 2) Furthermore, while this embodiment describes an example in which the discharge drive element MD1 and the circulation drive element MD2 are composed of DMOS transistors, the invention is not limited to this. For example, at least one of the discharge drive element MD1 and the circulation drive element MD2 may be composed of a SiC (Silicon Carbide) MOSFET.

[0052] The disclosure of this embodiment includes configurations represented by the following liquid dispensing head, liquid dispensing device, control method for the liquid dispensing device, and program.

[0053] <Configuration 1> A discharge module having a discharge drive element and a discharge heater electrically connectable to the discharge drive element, A circulation module is arranged in conjunction with the discharge module and includes a circulation drive element and a circulation heater electrically connectable to the circulation drive element. Control means for controlling the discharge drive element and the circulation drive element to either a conductive state or a non-conductive state, Equipped with, The control means is characterized by making the discharge drive frequency used to drive the discharge drive element and the circulation drive frequency used to drive the circulation drive element different.

[0054] <Configuration 2> Multiple units of the discharge module and the circulation module are provided in the same number. The liquid discharge head according to Configuration 1, wherein the control means sets the number of time divisions of the time-division selection signal for circulation, which drives the circulation drive element in a time-division manner, to be greater than the number of time divisions of the time-division selection signal for discharge, which drives the discharge drive element in a time-division manner.

[0055] <Structure 3> A decoder circuit that, with respect to the number of input bits of the input data, expands the number of output bits of the output data into a power of 2 for the number of input bits of the output drive element, using the time division ratio of the output drive element as the number of input bits of the input data. The liquid discharge head according to configuration 2, further comprising: a circulating decoder circuit that expands the number of output bits to the number of input bits as the time division number of the circulating drive element, where 2 is the power of the number of input bits plus 1.

[0056] <Structure 4> The control means drives the discharge drive elements in a time-division manner within discharge groups, which are divided into predetermined numbers from among the multiple discharge modules. The liquid discharge head according to configuration 2, wherein the control means drives the circulation drive elements in a time-division manner within circulation groups, which are divided into predetermined numbers from among the plurality of circulation modules.

[0057] <Composition 5> The liquid discharge head according to configuration 4, wherein the control means exclusively selects the circulation group from the discharge group.

[0058] <Composition 6> The liquid dispensing head according to configuration 2, further comprising a dispensing cycle counter circuit that stops the time-division driving of the circulating drive element at predetermined cycles of the time-division driving of the dispensing heater by the dispensing drive element based on the time-division selection signal for dispensing.

[0059] <Composition 7> Multiple units of the discharge module and the circulation module are provided in the same number. The liquid discharge head according to Configuration 1, wherein the control means sets the number of time divisions of the time-division selection signal for discharge, which drives the discharge drive element in a time-division manner, to be greater than the number of time divisions of the time-division selection signal for circulation, which drives the circulation drive element in a time-division manner.

[0060] <Structure 8> The liquid discharge head according to configuration 1, wherein the discharge heater and the circulation heater are connected to a common power supply voltage and a common ground potential.

[0061] <Composition 9> The liquid discharge head described in Configuration 1, wherein the discharge heater and the circulation heater are constructed using the same semiconductor process.

[0062] <Composition 10> The liquid discharge head described in configuration 1, wherein the discharge heater and the circulation heater are made of the same material.

[0063] <Composition 11> A liquid dispensing head as described in any one of configurations 1 to 10, A carriage equipped with the aforementioned liquid discharge head and which reciprocates in the main scanning direction, A conveyor roller is provided below the carriage to transport the discharged medium in the sub-scanning direction, A liquid dispensing device characterized by comprising the following features. [Explanation of symbols]

[0064] 11 Discharge Module 12 Circulation Modules 15 Decoder Circuit 16. Circulation group selection circuit 202 Controller 203 Power supply circuit

Claims

1. A discharge module having a discharge drive element and a discharge heater electrically connectable to the discharge drive element, A circulation module is arranged in conjunction with the discharge module and includes a circulation drive element and a circulation heater electrically connectable to the circulation drive element. Control means for controlling the discharge drive element and the circulation drive element to either a conductive state or a non-conductive state, Equipped with, The control means is characterized by making the discharge drive frequency used to drive the discharge drive element and the circulation drive frequency used to drive the circulation drive element different.

2. Multiple units of the discharge module and the circulation module are provided in the same number. The liquid discharge head according to claim 1, wherein the control means sets the number of time divisions of the time division selection signal for circulation, which drives the circulation drive element in a time division manner, to be greater than the number of time divisions of the time division selection signal for discharge, which drives the discharge drive element in a time division manner.

3. A decoder circuit that, with respect to the number of input bits of the input data, expands the number of output bits of the output data into a power of 2 for the number of input bits of the output drive element, using the time division ratio of the output drive element as the number of input bits of the input data, The liquid discharge head according to claim 2, further comprising: a circulating decoder circuit that, with respect to the input number of bits, expands the output number of bits to a power of 2 plus 1, with respect to the input number of bits, as the time division number of the circulating drive element.

4. The control means drives the discharge drive elements in a time-division manner within discharge groups, which are divided into predetermined numbers from among the multiple discharge modules. The liquid discharge head according to claim 2, wherein the control means drives the circulation drive elements in a time-division manner within circulation groups, which are divided into predetermined numbers from among the plurality of circulation modules.

5. The liquid discharge head according to claim 4, wherein the control means exclusively selects the circulation group from the discharge group.

6. The liquid dispensing head according to claim 2, further comprising a dispensing cycle counter circuit that stops the time-division driving of the circulating drive element at predetermined cycles of the time-division driving of the dispensing heater by the dispensing drive element based on the time-division selection signal for dispensing.

7. Multiple units of the discharge module and the circulation module are provided in the same number. The liquid discharge head according to claim 1, wherein the control means sets the number of time divisions of the time division selection signal for discharge, which drives the discharge drive element in a time division manner, to be greater than the number of time divisions of the time division selection signal for circulation, which drives the circulation drive element in a time division manner.

8. The liquid discharge head according to claim 1, wherein the discharge heater and the circulation heater are connected to a common power supply voltage and a common ground potential.

9. The liquid discharge head according to claim 1, wherein the discharge heater and the circulation heater are constructed using the same semiconductor process.

10. The liquid discharge head according to claim 1, wherein the discharge heater and the circulation heater are made of the same material.

11. A liquid dispensing head according to any one of claims 1 to 10, A carriage equipped with the aforementioned liquid discharge head and which reciprocates in the main scanning direction, A conveyor roller is provided below the carriage to transport the discharged medium in the sub-scanning direction, A liquid dispensing device characterized by comprising the following features.

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