Electrical circuit board and liquid ejection device

Abstract

To arrange a booster circuit, other circuits and wiring in a miniaturized electric circuit board, while securing reliability and safety.SOLUTION: An electric circuit board includes a booster circuit for generating a pump driving signal having a pump driving voltage for driving a circulation pump for circulating a liquid by boosting a pump reference signal having a reference voltage on the basis of a booster circuit driving signal, a first wiring for transmitting the pump driving signal, a second wiring for transmitting the pump reference signal, a third wiring for transmitting the booster circuit driving signal, and a plurality of fourth wirings for transmitting a signal related to a discharge element for discharging the liquid, where the second wiring and the third wiring have a part arranged at a closer position than a protective distance from the first wiring, to which a short circuit protective circuit is attached, and the plurality of fourth wirings include one or more first kind of wirings arranged at a position farther than the protective distance from the first wiring.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a circuit board and a liquid ejection device including the same. [Background technology]

[0002] Image forming devices that print on recording materials are found in printers, multifunction peripherals, facsimile machines, and other devices. Known image forming device types include inkjet, wire dot, thermal, and electrophotographic. Inkjet image forming devices, also known as liquid ejection devices, have a liquid ejection head containing ejection elements for ejecting ink. The ejection elements include pressure chambers, ejection orifices, and energy conversion elements. In liquid ejection devices, ink is supplied from an ink supply source to a pressure chamber via a flow path. The ink supplied to the pressure chamber is propelled toward the recording material through the ejection orifices by ejection energy provided by the energy conversion element, and lands on the recording material as flying droplets. This process prints on the recording material. Liquid ejection heads that use thermal energy to eject ink have been widely used due to their advantages, such as the ability to arrange ejection orifices at high density and the ease of overall compactness. Furthermore, in recent years, liquid ejection devices have been developed that circulate liquid within the liquid ejection head to remove air bubbles from the flow path and prevent ink from thickening near the ejection orifices. Patent Document 1 discloses a liquid ejection device that circulates ink in a liquid ejection head using a circulation pump. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-30350 Summary of the Invention [Problem to be solved by the invention]

[0004] In the liquid ejection device disclosed in Patent Document 1, the circulation pump is driven at a high voltage of 120 to 300 V peak-to-peak to circulate ink at a desired flow rate. Such high voltages may have undesirable effects on users and peripheral components. Furthermore, in the case of a scanning-type liquid ejection head that scans the liquid ejection head in the main scanning direction, it is desirable to configure the circulation channel inside the head to avoid complex ink circulation channels and increased device size. To configure the circulation channel inside the head, the circulation pump must also be located inside the head, but this increases the head size. A larger head increases the size of the liquid ejection device. Therefore, to avoid increasing the size of the liquid ejection device, it is necessary to miniaturize the circulation pump. To achieve the desired circulation capacity from a miniaturized circulation pump, the circulation pump must be driven at a high voltage. A configuration in which a high voltage is supplied to the liquid ejection head from outside the liquid ejection head requires providing high-voltage electrical contacts at the interface between the outside and the liquid ejection head. This raises the risk of a user coming into contact with such electrical contacts when, for example, replacing the liquid ejection head. To avoid this, for example, a boost circuit may be provided inside the liquid ejection head, and the boost circuit may boost an externally input low voltage to a high voltage. However, this requires the provision of other circuits and wiring inside the liquid ejection head. Furthermore, to achieve miniaturization, the boost circuit, other circuits, and wiring must be provided on the same electrical circuit board. In such cases, there is a risk that the high voltage output by the boost circuit will affect the other circuits and wiring.

[0005] The present disclosure has been made in consideration of the above points, and aims to arrange a boost circuit, other circuits, and wiring on a miniaturized electric circuit board while ensuring reliability and safety. [Means for solving the problem]

[0006] One aspect of the present disclosure is an electric circuit board comprising: a boost circuit that generates a pump drive signal having a pump drive voltage for driving a circulation pump that circulates a liquid by boosting a pump reference signal having a reference voltage based on a boost circuit drive signal; a first wiring for transmitting the pump drive signal; a second wiring for transmitting the pump reference signal; a third wiring for transmitting the boost circuit drive signal; and a plurality of fourth wirings for transmitting signals related to ejection elements that eject liquid, wherein the second wiring and the third wiring have portions that are arranged closer to the first wiring than a protection distance and are equipped with a short circuit protection circuit, and the plurality of fourth wirings include one or more first-type wirings that are arranged at a position away from the first wiring by the predetermined protection distance. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to arrange a boost circuit, other circuits, and wiring on a miniaturized electric circuit board while ensuring reliability and safety. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1A is a schematic perspective view showing an outline of a liquid ejection device according to the present disclosure; FIG. 1B is a functional block diagram of the liquid ejection device according to the present disclosure; [Figure 2] FIG. 1 is an exploded perspective view of a liquid ejection head according to the present disclosure. [Figure 3] Schematic diagram of the appearance of the liquid circulation unit of the present disclosure. [Figure 4] Schematic diagram of an ink circulation flow path according to the present disclosure. [Figure 5] Schematic diagram showing the configuration for electrical connections to drive a circulation pump. [Figure 6] FIG. 1 is a schematic plan view showing the layout of a mounting surface of an electric circuit board according to a first embodiment of the present disclosure; [Figure 7] Schematic perspective view of an electric circuit board according to the present disclosure. [Figure 8] Schematic cross-sectional view of a cross section including a through-hole of an electric circuit board according to the present disclosure. [Figure 9]A list of representative wirings arranged on the electric circuit board of the present disclosure [Figure 10] FIG. 10 is a schematic plan view showing the layout of a mounting surface of an electric circuit board according to a third embodiment of the present disclosure. [Figure 11] FIG. 10 is a schematic plan view showing the layout of a mounting surface of another electric circuit board according to a third embodiment of the present disclosure; [Figure 12] FIG. 10 is a schematic plan view showing the layout of a mounting surface of yet another electric circuit board according to the third embodiment of the present disclosure. [Figure 13] FIG. 10 is a schematic plan view showing the layout of a mounting surface of yet another electric circuit board according to the third embodiment of the present disclosure. [Figure 14] FIG. 10 is a schematic plan view showing the layout of the pad surface of the electric circuit board according to the fourth embodiment; [Figure 15] FIG. 10 is a schematic plan view showing the layout of the pad surface of the electric circuit board according to the fifth embodiment; [Figure 16] FIG. 13 is a schematic plan view showing the layout of the pad surface of the electric circuit board according to the sixth embodiment; [Figure 17] FIG. 13 is a schematic plan view showing the layout of a mounting surface of an electric circuit board according to a seventh embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations may be omitted.

[0010] FIG. 1(a) is a schematic perspective view showing an outline of a liquid ejection device of the present disclosure, and FIG. 1(b) is a functional block diagram of the liquid ejection device of the present disclosure.

[0011] The liquid ejection apparatus according to this embodiment is a serial scan type inkjet printing apparatus (hereinafter simply referred to as "printing apparatus") 101 that ejects ink from a liquid ejection head 201 to print an image on a printing medium P. The liquid ejection head 201, which serves as an inkjet liquid ejection head, is mounted on a carriage 121. The carriage 121 reciprocates along a guide shaft 132 that extends in the main scanning direction, as indicated by a double-headed arrow X. The printing medium P is transported in a sub-scanning direction that intersects (orthogonal in this example) the main scanning direction, as indicated by an arrow Y, by transport rollers 133, 134, 135, and 136.

[0012] The liquid ejection head 201 includes a plurality of liquid circulation units 204 and an ejection unit 206. The plurality of liquid circulation units 204 circulates the ink flowing through the ejection unit 206. A plurality of ejection elements for ejecting ink are formed in an ejection module 209 provided in the ejection unit 206. The element drive signal generated by the head driver 123 drives the plurality of ejection elements to eject ink, and is supplied to the plurality of ejection elements formed in the ejection module 209 via an electric circuit board 205 and an electric wiring tape 208.

[0013] A guide 131 is connected to the carriage 121. Electrical wiring and supply tubes are arranged in the guide 131. The electrical wiring and supply tubes supply ink and electrical signals required for ink ejection by the multiple ejection elements formed in the ejection module 209 to the carriage 121.

[0014] A processor 142 such as a CPU controls the recording device 101 by reading and executing programs stored in a ROM 143. A RAM 144 is used as a work area when the processor 142 reads and executes programs. The processor 142 controls a head driver 123 based on image data supplied from a host device 111 connected to the recording device 101. The processor 142 also controls a carriage motor 146 for moving the carriage 121 via a motor driver 145. The processor 142 also controls a conveyance motor 148 for conveying the recording medium P via conveyance rollers 133, 134, 135, and 136 via a motor driver 147.

[0015] The liquid ejection head 201 is capable of full-color printing using CMYK (cyan, magenta, yellow, black) inks. A cap unit (not shown) is disposed adjacent to the transport path of the recording medium P. When the recording device 101 is not performing a recording operation, the cap unit moves relatively to a position that covers the ejection surface of the liquid ejection head 201, and performs capping to prevent the ejection ports on the ejection surface from drying out, filling the head with ink, and suction operations to restore the head's functionality.

[0016] (Description of Liquid Ejection Head Configuration) FIG. 2 shows an exploded perspective view of a liquid ejection head 201 according to this embodiment. As shown in FIG. 2, the liquid ejection head 201 includes multiple liquid circulation units 204, as described above. The multiple circulation units 54 include circulation units 204m, 204y, 204k, and 204c, each corresponding to a different color of ink, and are housed within a flow path member 202. A flow path is provided in the circulation unit 54, and a flow path is also provided in the flow path member 202. These flow paths can be connected by screw fastening with a sealing member sandwiched between them, or by welding. Note that the ejection head 201 according to this embodiment contains four types of ink, and accordingly, the number of circulation units 54 is also four, but the present disclosure is not limited to this. The following description will be given assuming that the number of types of ink is four, but this does not limit the number of types of ink to four in the present disclosure.

[0017] As shown in FIG. 2, the flow path member 202 is provided with four joints 203 for receiving ink supplied from the recording apparatus 101 main body via supply tubes disposed in the guide 131. The four joints 203 are connected to circulation units 204m, 204y, 204k, and 204c in a one-to-one relationship. When the liquid ejection head 201 is mounted on the recording apparatus 101 main body, each supply tube connected to an ink tank 151 of each color (see FIG. 1) is connected to each joint 203. The ink of each color supplied from each supply tube passes through each joint 203 and is supplied to each circulation unit 204m, 204y, 204k, and 204c. A discharge unit 206 is connected to the bottom surface of the flow path member 202. The ink of each color supplied to each circulation unit 204m, 204y, 204k, and 204c passes through the flow path member 202 and is supplied to the discharge unit 206.

[0018] As shown in FIG. 2 , the ejection unit 206 includes an ejection module 209 in which a plurality of ejection elements for ejecting ink are arranged, and a support member 207. The ejection unit 206 also includes an electric wiring tape 208 for sending an electric signal to the ejection module 209, and a cover member 210 for covering the electric wiring tape 208. The ejection module 209 and the electric wiring tape 208 are adhesively fixed to the support member 207, and the cover member 210 is adhesively joined to them so as to cover their surfaces. The ejection module 209 and the electric wiring tape 208 are electrically connected by wire bonding. Here, a method such as flying lead bonding can be used as the electrical connection method. A portion of the cover member 210 corresponding to the ejection module 209 is open. The ejection unit 206 and the flow path member 202 can be connected by an adhesive bonding method or a fixing method using screws with a sealing member sandwiched therebetween.

[0019] The surface of flow path member 202 opposite to the surface on which joint 203 is disposed is a contact surface. Electric circuit board 205 is disposed on the contact surface. Electric circuit board 205 may be fixed to flow path member 202 by crimping or adhesive, or by double-sided tape.

[0020] 1, the electric circuit board 205 relays electric signals transmitted between the carriage board 122 and the discharge unit 206. The electric circuit board 205 also relays electric signals transmitted between the carriage board 122 and the liquid circulation unit 204.

[0021] The electric wiring tape 208 included in the discharge unit 206 is connected to the electric circuit board 205 by ACF pressure bonding, wire bonding, flying lead bonding, etc. The electric wiring tape 208 relays electric signals transmitted between the electric circuit board 205 and the discharge module 209 included in the discharge unit 206.

[0022] (Explanation of the circulation flow path) 3 is a schematic diagram showing the appearance of the liquid circulation unit 204 applied to the recording apparatus 101. One liquid circulation unit 204 per color is arranged in the flow path member 202. The liquid circulation unit 204 includes a first pressure adjustment mechanism 302, a second pressure adjustment mechanism 304, a filter 301, and a circulation pump 303.

[0023] 4 is a schematic diagram showing a circulation flow path for one color that is applied to the recording apparatus 101. Ink is pressurized and supplied from the ink tank 151 to the liquid ejection head 201 by an external pump 152. After foreign matter is removed from the ink by a filter 301, the ink is supplied to a first valve chamber 401 of a first pressure adjustment mechanism 302. The pressure of the ink is then adjusted as it flows into a first pressure control chamber 402 that communicates with the first valve chamber 401 via a valve (not shown).

[0024] The circulation pump 303 is a piezoelectric diaphragm pump that changes the volume of the pump chamber by alternately inputting a pump drive signal having a pump drive voltage to two piezoelectric elements attached to the diaphragm, and the pressure fluctuations cause two check valves to move alternately to send ink. The circulation pump 303 is driven to send ink from a pump inlet flow path 407 on the downstream side to a pump outlet flow path 408 on the upstream side.

[0025] By driving the circulation pump 303, ink whose pressure has been adjusted in the first pressure control chamber 402 is supplied to the supply flow path 405 and the bypass flow path 409. The supply flow path 405 is a flow path formed in the flow path member 202, and is connected to the discharge unit 206. The recovery flow path 406 is also a flow path formed in the flow path member 202, and is connected to the discharge unit 206.

[0026] The ejection unit 206 includes an ejection module 209, and the ejection module 209 has multiple ejection elements formed therein. Each ejection element has a pressure chamber, an ejection port, and an energy conversion element. The pressure chamber and the ejection port are in communication with each other. The ejection ports are arranged as openings on the ejection surface. Ink supplied to the supply flow path 405 is supplied to multiple pressure chambers formed in the ejection module 209 of the ejection unit 206. Ink in the pressure chambers is ejected from the ejection port by energy output from the energy conversion element. Ink that is not ejected from the ejection port is discharged from the pressure chamber to a recovery flow path 406, and then supplied to the second pressure control chamber 404 of the second pressure adjustment mechanism 304.

[0027] Furthermore, ink supplied to the second valve chamber 403 of the second pressure adjustment mechanism 304 is supplied to a second pressure control chamber 404 that communicates with the second valve chamber 403 via a valve.

[0028] The ink supplied to the second pressure control chamber 404 is supplied to the pump inlet flow path 407, passes through the circulation pump 303, and is then supplied to the pump outlet flow path 408, and is then supplied to the first pressure control chamber 402. However, there are also times when at least a portion of the ink supplied to the second pressure control chamber 404 is supplied to the flow path member 202 via the recovery flow path 406. By configuring the ink to circulate by the circulation pump 303 through the ejection elements formed in the ejection module 209 in this way, it is possible to suppress an increase in viscosity of the ink in the ejection module 209.

[0029] The circulation flow path is not limited to a configuration that passes through the ejection module 209, but may be configured to circulate the ink in the ejection unit 206 within a range that is effective in suppressing the increase in ink viscosity in the ejection module 209.

[0030] (Explanation of the circulation pump drive mechanism) 5 is a schematic diagram showing the configuration for electrical connections for driving the circulation pump 303. Various drive signals are sent from the processor 142 mounted on the main board 141 inside the recording apparatus 101 to the carriage board 122 (also referred to as the "upper board") mounted on the carriage 121 via the main board 141 and a flexible flat cable (FFC) 501. The various drive signals include signals related to the circulation pump 303 included in the liquid circulation unit 204 and signals related to the discharge unit 206, which will be described later.

[0031] Also, various drive signals are sent from the carriage substrate 122 to the electric circuit board 205 via an electric connection section 504 that is a contact connection. Here, the electric connection section 504 includes a plurality of pins 505 on the carriage 121 side as shown in Fig. 5 and a plurality of pads (also called "upper terminals") Tn (see Fig. 14) arranged on the pad surface 502 of the electric circuit board 205, and an electric connection is established when each pin comes into contact with its corresponding pad.

[0032] As will be described later, the electric circuit board 205 is provided with a boost circuit 601 (see FIG. 6) as boosting means for boosting the pump reference voltage of the pump reference signal based on a boost circuit drive signal. The boost circuit 601 boosts the pump reference voltage to a voltage specified by the boost circuit drive signal to generate a pump drive signal having a pump drive voltage. The pump drive signal is supplied to a connector terminal 608 (FIG. 6) disposed on the electric circuit board 205 via a pair of switching circuits 602 (FIG. 6). The pump drive signal is supplied to the four circulation pumps 303 via harness wiring 506 connected to the connector terminal 608. The four circulation pumps 303 are driven to circulate ink by the pump drive signal having the pump drive voltage.

[0033] (Explanation of the driving of ejection elements) Signals for driving the plurality of ejection elements formed in the ejection module 209 are supplied to the electric circuit board 205, and then supplied to the ejection module 209 via the electric wiring tape 208. To explain some of the signals in more detail, various drive signals for driving the ejection elements are supplied to differential transmission wiring and analog signal wiring provided on the electric circuit board 205, and then supplied to the ejection module 209 via the electric wiring tape 208. The plurality of ejection elements formed in the ejection module 209 are driven at any timing and intensity by these drive signals.

[0034] [First embodiment] FIG. 6 is a schematic diagram of a circuit disposed on the mounting surface 503 of the electric circuit board 205 according to the first embodiment. When viewed from the mounting surface 503, the pad surface 502 on which the pads Tn with which the pins 505 contact are disposed is the opposite surface (see FIG. 5). In FIG. 6, 612 denotes a pump reference signal wiring (also referred to as the "second wiring"). A pump reference signal supplied from the pin 505 to the pad T20 (see FIG. 14) is supplied to the boost circuit 601 via the through-hole 607 and the pump reference signal wiring 612. The boost circuit 601 generates a pump drive signal having a pump drive voltage by boosting the pump reference voltage of the pump reference signal. Here, the pump drive voltage is specified by a boost circuit drive signal supplied from the FPGA 603 to the boost circuit 601 via a boost circuit drive signal wiring (also referred to as the "third wiring") 614. In the first embodiment, the pump reference voltage is 5 V. The pump drive voltage is 70 V.

[0035] In FIG. 6 , the mounting surface 503 has four wirings labeled with the reference numeral 611, which are collectively referred to as pump drive signal wirings or first wirings. As described above, a pair of switching circuits 602 is disposed on the electric circuit board 205. A pump drive signal having a continuous pump drive voltage is supplied to each of the switching circuits 602 via pump drive signal wirings 611 disposed between the boost circuit 601 and each of the switching circuits 602. A pump drive control signal is supplied to the pair of switching circuits 602 from the FPGA 603 via pump drive control signal wirings 613. Based on the pump drive control signal, the pair of switching circuits 602 generate pump drive signals that complementarily alternate between the pump drive voltage and zero volts. Two series of connector terminals 608 are disposed on the electric circuit board 205. The pump drive signals generated by each of the switching circuits 602 are supplied to the two series of connector terminals 608 via pump drive signal wirings 611 disposed between each of the switching circuits 602 and the connector terminals 608 of each series. Here, the input terminals of the circulation pumps 303 are connected to the connector terminals 608 via the harness wiring 506. That is, one input terminal of each circulation pump 303 is connected to one series of connector terminals 608, and the other input terminal is connected to the other series of connector terminals 608. As a result, a pump drive signal having a pump drive voltage is alternately supplied to a pair of input terminals provided on each circulation pump 303. When focusing on one input terminal, the pump drive signal is supplied intermittently.

[0036] Reference numeral 615 denotes an FPGA power supply wiring for supplying power to operate the FPGA 603 to the FPGA 603. The FPGA 603 receives an IC control signal from the head driver 123 on the carriage substrate 122 via the electrical connection part 504, the pad T17 (see FIG. 14) on the pad surface 502, the through hole 607, and the IC control signal wiring 625. Then, the FPGA 603 generates the above-mentioned pump drive control signal and boost circuit drive signal based on the IC control signal.

[0037] Reference numeral 604 denotes an EEPROM. The EEPROM 604 receives an EEPROM setting signal from the head driver 123 via the electrical connection part 504, the pad T16 (see FIG. 14) on the pad surface, the through-hole 607, and the EEPROM setting signal wiring 616. The EEPROM 604 also generates a signal to be supplied to the FPGA 603, and further manages signals indicating the head drive conditions, etc.

[0038] Reference numeral 620 denotes a heater power supply wiring for supplying a heater power supply voltage for the heater to the energy conversion element (heater element in this embodiment) provided in the ejection element formed in the ejection module 209. Reference numeral 619 denotes a heater ground wiring for supplying a heater ground voltage (0 V) corresponding to the heater power supply voltage to the energy conversion element.

[0039] Reference numeral 622 denotes a logic power supply wiring for supplying logic power corresponding to a logic signal indicating drive timing, etc., to the energy conversion elements provided in the ejection elements formed in the ejection module 209. Reference numeral 617 denotes a logic ground wiring for supplying a reference voltage (0 V) corresponding to the logic power supply to the energy conversion elements. The logic power supply wiring 622 is also connected to the FPGA 603 and the EEPROM 604 in order to supply the FPGA 603 and the EEPROM 604 with the logic power supply wiring 622. The logic ground wiring 617 is also connected to the FPGA 603 and the EEPROM 604 in order to supply the logic power supply wiring 622 and the logic ground wiring 617 with a reference voltage corresponding to the logic power supply. The FPGA 603 and the EEPROM 604 are logic circuits mounted on the electric circuit board 205.

[0040] Reference numeral 621 denotes an ejection element output wiring (analog) for transmitting an analog signal indicating the temperature of the ejection module 209 in a direction from the ejection module 209 toward the electrical connection part 504 .

[0041] Reference numeral 624 denotes an ejection element output wiring (digital) for transmitting a digital signal indicating the surface state of the heater electrode of ejection module 209 in a direction from ejection module 209 toward electrical connection part 504 .

[0042] Reference numeral 618 denotes a discharge element drive signal wiring (differential) for supplying a signal indicating drive timing by a differential transmission method to the energy conversion elements provided in the discharge elements formed in the discharge module 209. Reference numeral 623 denotes a discharge element drive signal wiring (non-differential) for supplying another signal indicating drive timing by a method other than the differential transmission method to the energy conversion elements provided in the discharge elements formed in the discharge module 209.

[0043] A part of the wiring is connected to a lead terminal 606. The lead terminal 606 is connected to a discharge module 209 via an electric wiring tape 208.

[0044] In this embodiment, as already explained, the pump drive signal wiring designated by the reference numeral 611 carries a pump drive signal, whether continuous or intermittent, having a pump drive voltage of, for example, 70 V. This pump drive signal may cause ion migration. Ion migration is a phenomenon in which metal ions contained in wiring subjected to high voltage dissolve into an electric circuit board, move across the board toward low-voltage wiring due to an electric field, and when they reach the low-voltage wiring, they combine with electrons and precipitate. The precipitation in the low-voltage wiring causes the growth of resin-like crystals called dendrites, which can cause short circuits between wiring.

[0045] Therefore, in this embodiment, as a countermeasure against ion migration, a protection region Z is provided around the pump drive signal wiring. FIG. 6 schematically shows the protection region Z, with the upper edge of the protection region Z coinciding with the lower edges of the boost circuit 601 and the switching circuit 602. The lower edge of the protection region Z is spaced a distance D below the upper edge. There is a possibility that the terminals connected to the pump drive signal wiring 611 of the boost circuit 601 and the switching circuit 602 may be located near the lower ends of these circuits 601 and 602. Taking this possibility into consideration, the protection region Z is provided as shown in FIG. 6 so that, in principle, other wiring is arranged at least the distance D from the pump drive signal wiring 611. Here, the distance D is referred to as the protection distance.

[0046] In some configurations, the terminals connected to the pump drive signal wiring 611 of the boost circuit 601 and the switching circuit 602 are located near the vertical center of these circuits 601 and 602, and the pump drive signal wiring 611 extends horizontally as viewed in the figure. In such a configuration, the upper edge of the protection area Z is located near the vertical center of the boost circuit 601 and the switching circuit 602. Therefore, the lower edge of the protection area Z is also located higher than the position shown in FIG. 6. The protection area Z is not defined based on the positions of the boost circuit 601 and the switching circuit 602, but is defined by the position of the pump drive signal wiring 611 and the positions of the terminals of the boost circuit 601 and the switching circuit 602 connected thereto (referred to as "associated terminals"). Here, the position of the associated terminal coincides with the position of one end of the pump drive signal wiring 611, so the protection area Z is essentially defined by the position of the pump drive signal wiring 611.

[0047] 6 , only the pump reference signal wiring 612, the pump drive control signal wiring 613, the boost circuit drive signal wiring 614, and the logic ground wiring 617 have portions disposed in the protection area Z. These four wirings 612, 613, 614, and 617 are wirings that need to be connected to one or both terminals of the boost circuit 601 and the switching circuit 602. Therefore, it is unavoidable that these wirings have portions disposed in the protection area Z. However, a short protection circuit 605 is connected to three of these four wirings 612, 613, 614, and 617, excluding the logic ground wiring 617: the wirings 612, 613, and 614. Connecting the short protection circuit 605 to these three wirings 612, 613, and 614 prevents fire, smoke, and the like from occurring even if these wirings 612, 613, and 614 are shorted to the pump drive signal wiring 611. Depending on the type of signal assigned to the wiring, it may not be possible to connect the short protection circuit 605 to the wiring. However, connecting the short protection circuit 605 does not pose a problem for the pump reference signal wiring 612, the pump drive control signal wiring 613, and the boost circuit drive signal wiring 614. Connecting the short protection circuit 605 to the logic ground wiring 617 is also possible, but since this would mean connecting the short protection circuit 605 between grounds, we have deliberately refrained from connecting the short protection circuit to the logic ground wiring 617.

[0048] The short-circuit protection circuit 605 may be, for example, a Zener diode or a varistor. For example, a Zener diode or a varistor is inserted between the pump reference signal wiring 612 and ground. This prevents the voltage of the pump reference signal wiring 612 from exceeding the breakdown voltage of the Zener diode or the limiting voltage of the varistor. As shown in the table of FIG. 9 , which will be referred to later, a 5V DC or AC signal is assigned to the pump reference signal wiring 612, the pump drive control signal wiring 613, and the boost circuit drive signal wiring 614. Therefore, a Zener diode with a breakdown voltage of 5.5V may be connected to these wirings.

[0049] All wiring other than the above four wirings 612, 613, 614, and 617 does not have a portion disposed in the protection area Z. In other words, all wiring other than the above four wirings 612, 613, 614, and 617 is disposed in an area excluding the protection area Z.

[0050] 7 is a schematic perspective view of the electric circuit board 205 of the present disclosure. 607u is a through-hole corresponding to the pump reference signal wiring 612. The through-hole 607u is connected to the pump reference signal wiring 612 arranged on the mounting surface 503 and the pump reference signal wiring 612b arranged on the pad surface 502. A pad T20 is arranged on the pad surface. On the pad surface 502, the pad T20 is connected to the pump reference signal wiring 612b. The pump reference signal wiring 612 is a piece of first-surface wiring (mounting surface wiring), and the pump reference signal wiring 612b is a piece of second-surface wiring (pad surface wiring).

[0051] The pump reference signal supplied from the pin 505 to the pad T20 is supplied to the boost circuit 601 via the pump reference signal wiring 612b, the through-hole 607u, and the pump reference signal wiring 612.

[0052] Reference numeral 607v denotes a through hole corresponding to the ejection element drive signal wiring (differential) 618. The through hole 607v is connected to the ejection element drive signal wiring (differential) 618 arranged on the mounting surface 503 and the ejection element drive signal wiring (differential) 618b arranged on the pad surface 502. A pad T14 is arranged on the pad surface 502. On the pad surface 502, the pad T14 is connected to the ejection element drive signal wiring (differential) 618b. On the mounting surface 503, the ejection element drive signal wiring (differential) 618 is connected to a lead terminal 606. The ejection element drive signal wiring (differential) 618 represents one first surface wiring (mounting surface wiring), and the ejection element drive signal wiring (differential) 618b represents one second surface wiring (pad surface wiring). The ejection element drive signal wiring (differential) 618 is made up of a plurality of signal wirings because a positive phase signal and a negative phase signal are paired, but in FIG. 7, for simplicity of the drawing, it is shown as a single line.

[0053] The ejection element drive signal (differential) supplied from the pin 505 to the pad T14 is supplied to the lead terminal 606 via the ejection element drive signal wiring (differential) 618b, the through hole 607v, and the ejection element drive signal wiring (differential) 618. The ejection element drive signal (differential) supplied to the lead terminal 606 is supplied to a plurality of ejection elements formed in the ejection module 209 via the electric wiring tape 208.

[0054] 611a, 611b, and 611c are pump drive signal wiring. In Fig. 6, the pump drive signal wiring is shown as a single line 611, but in Fig. 7, it is shown as multiple pump drive signal wirings 611a, 611b, and 611c to explain the concept of protective distance D. Note that in the present disclosure, there is no limit to the number of pump drive signal wirings, and multiple pump drive signal wirings 611a, 611b, and 611c may be present.

[0055] A protection area Z11 is defined on one side of the pump drive signal wiring 611a, with a boundary line at a position distance D from the pump drive signal wiring 611a, and a protection area Z12 is defined on the other side, with a boundary line at a position distance D from the pump drive signal wiring 611a. Here, the area combining protection area Z11 and protection area Z12 is defined as protection area Z1. Furthermore, a protection area Z21 is defined on one side of the pump drive signal wiring 611b, with a boundary line at a position distance D from the pump drive signal wiring 611b, and a protection area Z22 is defined on the other side, with a boundary line at a position distance D from the pump drive signal wiring 611b. Here, the area combining protection area Z21 and protection area Z22 is defined as protection area Z2. Furthermore, a protection area Z31 is defined on one side of the pump drive signal wiring 611c, with a boundary line at a position distance D from the pump drive signal wiring 611c, and a protection area Z32 is defined on the other side, with a boundary line at a position distance D from the pump drive signal wiring 611c. Here, the combined area of ​​the protection area Z31 and the protection area Z32 is defined as the protection area Z3.

[0056] 7, the protection regions Z1, Z2, and Z3 partially overlap each other. An extended protection region Z=Z1∪Z2∪Z3 can be defined by taking the union of the protection regions Z1, Z2, and Z3.

[0057] The boundary line L between the extended protection area Z (= Z1∪Z2∪Z3) and the other area ￢Z (= ￢(Z1∪Z2∪Z3)) can be defined as the periphery of the protection area Z for the entire pump drive signal wiring 611a, 611b, 611c. Furthermore, the distance D from the boundary line L to the pump drive signal wiring closest to the boundary line L can be defined as the above-mentioned protection distance D for the entire pump drive signal wiring 611a, 611b, 611c. In the example of FIG. 7, the pump drive signal wiring closest to the boundary line L is the pump drive signal wiring 611a.

[0058] The pump drive signal wiring 611d shown in FIG. 7 is bent, and a bent boundary line L can be defined accordingly. As shown in FIG. 7, a protection area Z and a protection distance D can be defined for the bent pump drive signal wiring 611d. The protection area Z is a set of points excluding any points that are more than the distance D from any other point on the pump drive signal wiring 611d. The protection area Z can also be said to be a set of points Q2 that are less than the distance D from at least one point Q1 on the pump drive signal wiring 611d. As shown in FIG. 7, around the two bends on the protruding side (right side) of the pump drive signal wiring 611d, the protection area is centered at the bends and has a quadrant shape with a radius D. However, the protection area Z may be defined differently in consideration of the distribution of electric field strength near the pump drive signal wiring 611d.

[0059] Generally speaking, only one through hole 607 may be provided for one electrical wiring, or multiple through holes may be provided for one electrical wiring. Also, only one through hole may be provided for one electrode terminal, or multiple through holes may be provided for one electrode terminal. Furthermore, each electrical wiring may be provided only on the mounting surface 503, or only on the pad surface 502, or may be provided on both the mounting surface 503 and the pad surface 502 via the through hole 607. Signal wiring for signals shared by multiple devices may branch off midway.

[0060] In this embodiment, the diameter of the through-hole 607 is 0.6 mm, the copper plating thickness of the through-hole 607 is 25 μm, and the number of through-holes is arranged so that the current is 0.75 A / 1 through-hole or less.

[0061] 8 is a schematic diagram of a cross section including a through hole of the electric circuit board 205 of the present disclosure. Specifically, it is a schematic diagram of a cross section including a through hole 607u connected to the pump reference signal wiring 612. Reference numeral 803 denotes a core material of the electric circuit board 205, and 804 denotes a resist layer that covers the electric wiring.

[0062] In the layout shown in Fig. 7, the through-hole 607u is provided in an area that is not the protection area Z. In contrast, in Fig. 8, the through-hole 607u is intentionally placed in the protection area for the sake of explanation. Although the explanation will be based on such a hypothetical configuration, in reality, some kind of through-hole may be placed in the protection area Z.

[0063] Referring to FIG. 8, a pump reference signal wiring 612 is connected to the boost circuit 601. The pump reference signal wiring 612 is connected to a pump reference signal wiring 612b disposed on the pad surface 502 via a through hole 607u disposed in the protection region Z. A pad T20 is disposed on the pad surface 502, and the pad T20 is connected to the pump reference signal wiring 612b. Also, a pump drive signal wiring 611 is disposed on the mounting surface 503. In the left - right direction of FIG. 7, the position of the right end of the pump drive signal wiring 611 substantially coincides with the central position of the boost circuit 601.

[0064] The distance from the pump drive signal wiring 611 to the through hole 607u is indicated by B1. Also, the thickness of the electric circuit board 205 is indicated by B2. When B1 + B2 < D, a protection region having a radius B3 (> 0) can be defined on the pad surface 502. The radius B3 is B3 = D-(B1 + B2) represented by this. Thus, B1 + B2 + B3 = D.

[0065] That is, in the configuration where B1 + B2 < D as shown in FIG. 8, the protection region Z is extended to the pad surface 502. In other words, the range defining the protection distance D from the pump drive signal wiring 611 to the boundary line between the protection region Z and the region excluding it is extended to the pad surface 502. As a result, the protection distance D is measured by the creepage distance across the mounting surface 503, the through hole, and the pad surface 502. This is because although the ion migration due to the pump drive signal on the pump drive signal wiring 611 does not pass through the core material 803, it reaches from the mounting surface 503 to the pad surface 502 via the through hole 607u. That is, because the metal ions eluted from the pump drive signal wiring 611 may reach the pad surface 502 via the through hole 607u.

[0066] 8, wiring 612 is provided, but the presence or absence of wiring 612 is irrelevant to the extension of protection area Z to pad surface 502. In other words, if any through-holes penetrating electric circuit board 205 are provided in protection area Z when viewed from mounting surface 503, protection area Z can be extended to pad surface 502 regardless of the type of wiring connected to the through-holes. Furthermore, protection area Z can be extended to pad surface 502 even if no wiring is connected to a through-hole that is provided in protection area Z when viewed from mounting surface 503. Furthermore, if a through-hole penetrating electric circuit board 205 is provided in protection area Z when viewed from mounting surface 503, it is desirable to adjust the wiring on pad surface 502 taking into account protection area Z that straddles mounting surface 503 and pad surface 502, as described above. In other words, the circular range (the circular range whose center is the through-hole and whose radius is B3) from the through-hole placed in protection area Z to a distance B3 (=D-(B1+B2)) can be defined as the protection area on the pad surface. Based on this definition, it is desirable to arrange wiring so as to avoid the protection area on pad surface 502.

[0067] FIG. 9 shows a list of representative wiring arranged on the electric circuit board 205 of the present disclosure. As shown in this list, the wiring is classified into wiring to which it is easy to connect a short protection circuit, wiring to which it is relatively easy, wiring to which it is difficult, and wiring to which it is not necessary. Wiring to which it is easy to connect a short protection circuit is wiring to which no problems will arise even if an inexpensive short protection circuit is connected. Wiring to which it is relatively easy to connect a short protection circuit is wiring to which no problems will arise if an inexpensive short protection circuit is connected. Wiring to which it is difficult to connect a short protection circuit is wiring to which problems will arise if a short protection circuit is connected.

[0068] The voltage of the heater power supply wiring is expressed as "24 or 21," which indicates that there are multiple heater power supply wirings, some of which have a voltage of 24V and others of 21V. The voltage of the EEPROM setting signal wiring is expressed as "33 or 0," which indicates that there are multiple EEPROM setting signal wirings, some of which have a voltage of 3.3V and others of 0V.

[0069] As shown in the table in Figure 9, a high voltage of 70V is applied to the pin connected to the pump drive signal wiring 611 of the boost circuit 601, the pin connected to the pump drive signal wiring 611 of the switching circuit 602, and the pump drive signal wiring 611. A protective distance D starting from these points was set to 6 mm. This value of 6 mm was set to satisfy the condition regarding clearances for secondary circuits stipulated in "2.10.3.4 Clearances for Secondary Circuits" of IEC 60950-1, a standard of the International Organization for Standardization.

[0070] An actual printing durability test was conducted for 2000 hours on the recording device 101 including the electric circuit board 205 according to this embodiment in an environment of 90% humidity and 35° C. temperature, and it was confirmed that good printing could be achieved.

[0071] [Second embodiment] In the first embodiment, the protection distance D is set to a value of 6 mm, for example. However, the protection distance D is a value that is set based on the power-on time required for the recording device 101 and the voltage difference between the pump drive voltage generated by the boost circuit 601 and the voltage of the signal on the wiring adjacent to the boost circuit 601, and is not limited to 6 mm. The protection distance D may also be set to satisfy conditions stipulated by other regulations.

[0072] In the first embodiment, the voltage of the pump drive signal wiring 611 was 70 V. In contrast, if the voltage of the pump drive signal wiring 611 is 35 V, for example, the voltage difference between the pump drive voltage of the pump drive signal generated by the boost circuit 601 and the voltage of the signal on the wiring adjacent to the boost circuit 601 is smaller than in the first embodiment. Therefore, the progress of ion migration also slows. Therefore, the protection distance D may be set shorter than in the first embodiment. If the rule is changed, for example, to "if there is a 40 V high-voltage wiring using other rules, the clearance distance shall be 3 mm," the wiring position may be changed in accordance with the changed rule.

[0073] In practice, the protection distance D was set to 5 mm, the pump drive voltage of the pump drive signal for driving the circulation pump 303 was set to 35 V, and an actual printing durability run was performed for 2000 hours in an environment with a humidity of 90% and a temperature of 35°C, with the configuration otherwise similar to that of the first embodiment. It was confirmed that good printing could be obtained in this actual printing durability run.

[0074] [Third embodiment] In the third embodiment, as shown in FIG. 10, a heater ground wiring 619, which does not need to be connected to a protection element that is a short-circuit protection circuit, may have a portion disposed in the protection region.

[0075] 11, heater power supply wiring 620, which has a voltage with a small potential difference relative to the pump drive voltage of pump drive signal wiring 611, may have a portion disposed in protection region Z. However, a protection element 605, which is a short circuit protection circuit, is connected to heater power supply wiring 620. Note that, as shown in the table of FIG. 9, there are multiple heater power supply wirings 620, and the voltage of some of the heater power supply wirings 620 is 24 V and the voltage of other heater power supply wirings 620 is 21 V.

[0076] 12, logic power supply wiring 622, which has a voltage with a large potential difference from the pump drive voltage of pump drive signal wiring 611, may have a portion disposed in protection region Z. However, protection element 605, which is a short protection circuit, is connected to logic power supply wiring 622. Note that the voltage of logic power supply wiring 622 is 3.3V as shown in the table of FIG.

[0077] On the other hand, connecting a short-circuit protection circuit to the ejection element drive signal wiring (differential) 618 is avoided. The ejection element drive signal wiring (differential) 618 is then arranged in an area other than the protection area Z. The reason for this is as follows. If a short-circuit protection circuit were connected to the ejection element drive signal wiring (differential) 618, the rise and fall of the voltage waveform of the ejection element drive signal transmitted by the ejection element drive signal wiring (differential) 618 would become slow. This would prevent high-speed data transfer for the high-speed printing required of an inkjet recording head. Furthermore, if the rise and fall of the voltage waveform becomes slow, the accuracy of detecting the original signal from the differential signal would also deteriorate. Therefore, connecting a short-circuit protection circuit to the ejection element drive signal wiring (differential) 618 is avoided, and accordingly, the ejection element drive signal wiring (differential) 618 is arranged in an area other than the protection area Z.

[0078] Furthermore, connecting a short-circuit protection circuit to the ejection element output wiring (analog) 621 is also avoided. The ejection element output wiring (analog) 621 is arranged in an area other than the protected area Z. The reason for this is as follows: An analog temperature signal, which indicates the temperature of the ejection module 209 as a voltage, is output from a temperature measurement terminal disposed in the ejection module 209. The analog temperature signal is transmitted from the liquid ejection head 201 to the main board 141 via the ejection element output wiring (analog) 621 and other wiring. If a short-circuit protection circuit were connected to the ejection element output wiring (analog) 621, an error such as an offset would occur in the temperature-to-voltage characteristics of the analog temperature signal, making it impossible to accurately measure the temperature of the ejection module 209 on the main board 141. This would make it impossible to accurately control the ink ejection amount taking the temperature of the ejection module 209 into consideration, adversely affecting print quality. Therefore, as described above, connecting a short-circuit protection circuit to the ejection element output wiring (analog) 621 is avoided, and the ejection element output wiring (analog) 621 is arranged in an area other than the protected area Z.

[0079] In this embodiment, the protection distance D is set to 6 mm, and the pump drive signal for driving the circulation pump 303 has a pump drive voltage of 70 V. The other configurations are the same as those of the first embodiment. In the configuration shown in FIG. 11, a short protection circuit is connected to the heater power supply wiring 620, and a portion of the heater power supply wiring 620 is arranged in the protection area Z. With this configuration, good printing was obtained even after 2000 hours of power-on time in an environment with a humidity of 90% and a temperature of 35°C.

[0080] On the other hand, in a reference configuration in which a short protection circuit was connected to the ejection element output wiring (analog) 621 and part of the ejection element output wiring (analog) 621 was arranged in the protected area Z, degradation in print quality was observed.

[0081] In another reference configuration in which a short-circuit protection circuit was connected to the ejection element drive signal wiring (differential) 618 and part of the ejection element drive signal wiring (differential) 618 was arranged in the protected area, high-speed printing was not possible.

[0082] Therefore, in order to ensure the degree of freedom in wiring, as shown in Fig. 13, the ejection element output wiring (analog) 621 and the ejection element drive signal wiring (differential) 618 are arranged in an area excluding the protection area Z. One or more other wirings may have a portion disposed in the protection area Z. However, a short protection circuit is connected to at least a portion of the wirings included in the one or more other wirings having a portion disposed in the protection area Z.

[0083] The enlargement ratio in Fig. 13 is greater than that in Fig. 10 to Fig. 12, and the protection distance D shown in Fig. 10 to Fig. 12 and the protection distance D shown in Fig. 13 are different on the drawings, but are the same in reality. Therefore, the electric circuit board 205 shown in Fig. 13 is smaller than the electric circuit board 205 shown in Fig. 10 to Fig. 12.

[0084] 13, the ejection element drive signal wiring (differential) 618 and the ejection element output wiring (analog) 621 are arranged in an area excluding the protected area Z. Wiring arranged in an area excluding the protected area Z in this way is referred to as first-type wiring.

[0085] 13, many wirings have portions that are arranged in the protection area Z. Therefore, many wirings require the connection of short-circuit protection circuits. The EEPROM setting signal wiring 616, logic ground wiring 617, heater ground wiring 619, and heater power supply wiring 620 have portions that are arranged in the protection area Z. The logic power supply wiring 622, ejection element drive signal wiring (non-differential) 623, ejection element output wiring (digital) 624, and IC control signal wiring 625 also have portions that are arranged in the protection area Z.

[0086] It is necessary to connect a short-circuit protection circuit to at least some of these wirings. Specifically, as shown in Fig. 13, short-circuit protection circuits are connected to the EEPROM setting signal wiring 616, heater power supply wiring 620, and logic power supply wiring 622. In addition, short-circuit protection circuits are also connected to the ejection element drive signal wiring (non-differential) 623, ejection element output wiring (digital) 624, and IC control signal wiring 625. Wiring that has a portion disposed in the protection region Z in this way and to which a short-circuit protection circuit is connected is referred to as second-type wiring.

[0087] 9, DC or AC signals of 3.3V, 21V, or 24V are assigned to wires 616, 620, 622, 623, 624, and 625. A Zener diode with a breakdown voltage slightly higher than the voltage of the signal assigned to that wire is connected to each wire. For example, a Zener diode with a breakdown voltage of 3.6V is connected to a wire assigned a 3.3V signal.

[0088] No short protection circuit is connected to the logic ground wiring 617 and the heater ground wiring 619. Wiring that has a portion disposed in the protection region Z and to which no short protection circuit is connected is referred to as type 3 wiring. It is desirable to connect a short protection circuit to the heater power supply wiring 620, but it is not necessarily required.

[0089] [Fourth embodiment] 14 is a diagram showing the layout of pads included in electrical connection portion 504 according to the first embodiment. Pads Tn are arranged on pad surface 502 of electric circuit board 205. Each pad is connected to a wiring arranged on mounting surface 503, and in FIG. 14, the correspondence between the number n included in each pad Tn and the wiring is as follows:

[0090] 5: Logic ground wiring 617 9: Discharge element output wiring (analog) 621 10: Ejection element output wiring (digital) 624 11: Heater power wiring 620 12: FPGA power wiring 615 13: Logic power wiring 622 14: Ejection element drive signal wiring (differential) 618 15: Heater ground wiring 619 16:EEPROM setting signal wiring 616 17: IC control signal wiring 625 18: Ejection element drive signal wiring (non-differential) 623 20: Pump reference signal wiring 612 22: (blank)

[0091] Although not shown in Fig. 14, through holes are provided at positions adjacent to each pad in contact with it in order to eliminate wiring on pad surface 502. Therefore, in a plan view, the through holes corresponding to each pad are arranged at approximately the same positions as each pad. The through holes corresponding to each pad connect each pad to the corresponding wiring arranged on mounting surface 503. Note that wiring connecting each pad to each through hole may be arranged on pad surface 502.

[0092] 10, 11, and 12, the through-hole 607 is disposed in a region below the protection region Z. That is, the through-hole 607 is disposed at a position spaced apart from the pump drive signal wiring 611 by a distance longer than the predetermined protection distance D. Therefore, as shown in FIG. 14, each pad is also disposed at a position spaced apart from the pump drive signal wiring 611 by a distance longer than the predetermined protection distance D in a plan view. Therefore, it is not necessary to provide the protection region Z of radius B3 on the pad surface 502 as described with reference to FIG. 8.

[0093] It should be noted that the blind vias and buried vias used in multilayer boards are different from the through holes described here.

[0094] [Fifth embodiment] In the fourth embodiment, as shown in Fig. 14, all of the pads are arranged at positions that are spaced apart from the pump drive signal wiring 611 by a distance longer than the predetermined protection distance D in a plan view. In contrast, in the fifth embodiment, as shown in Fig. 15, some of the pads are arranged at positions that are spaced apart from the pump drive signal wiring 611 by a distance shorter than the predetermined protection distance D in a plan view. In other words, some of the pads are arranged at positions that belong to the protection zone Z in a plan view.

[0095] 15, four pads T11 numbered 11 are disposed in a plan view at positions spaced apart from the pump drive signal wiring 611 by a distance shorter than a predetermined protection distance D. The pads T11 are connected to the heater power supply wiring 620.

[0096] The wiring for the leftmost pad of the four pads T11 is as follows: That is, the through-hole 607p is arranged in a position that belongs to the protection area Z in plan view (i.e., a position that is separated from the pump drive signal wiring 611 by a distance shorter than the predetermined protection distance D). In addition, a heater power supply wiring 620a for connecting the pad and the through-hole 607p is arranged on the pad surface 502, and a heater power supply wiring 620b for connecting the through-hole 607p and the lead terminal 606 is arranged on the mounting surface 503. The lead terminal 606 is connected to wiring on the electric wiring tape 208. Therefore, on the mounting surface 503, the heater power supply wiring 620b has a portion that is arranged in a position that belongs to the protection area Z (i.e., a position that is separated from the pump drive signal wiring 611 by a distance shorter than the predetermined protection distance D). Here, in the example shown in FIG. 13, it is explained that it is desirable to connect a short protection circuit to the heater power supply wiring 620. 15, in accordance with this, a short protection circuit 605 is connected to the heater power supply wiring 620b corresponding to the pad located at the left end of the four pads T11. Alternatively, a short protection circuit (not shown) may be connected to the heater power supply wiring 620a.

[0097] The wiring for the pad located at the right end of the four pads T11 is as follows: That is, through-hole 607q is arranged in a position that does not belong to protection area Z in plan view (i.e., a position that is separated from pump drive signal wiring 611 by a distance longer than the predetermined protection distance D). Furthermore, heater power supply wiring 620c for connecting the pad and through-hole 607q is arranged on pad surface 502, and heater power supply wiring 620d for connecting through-hole 607q and lead terminal 606 is arranged on mounting surface 503. Lead terminal 606 is connected to wiring on electric wiring tape 208. Therefore, heater power supply wiring 620d is arranged in a position that does not belong to protection area Z (i.e., a position that is separated from pump drive signal wiring 611 by a distance longer than the predetermined protection distance D). Therefore, there is no need to connect a short-circuit protection circuit to the heater power supply wiring 620d corresponding to the pad located at the right end of the four pads T11, and there is no need to connect a short-circuit protection circuit to the heater power supply wiring 620c.

[0098] As described above, through-hole 607p is disposed in a position that belongs to protection area Z in plan view (i.e., a position that is spaced from pump drive signal wiring 611 by a distance that is shorter than the predetermined protection distance D). Therefore, as described with reference to FIG. 8, a circular protection area Z having a radius of B3 and a center at through-hole 607p can be defined on putting surface 502. On putting surface 502, the above-mentioned four putts T11, including the putt on the left edge, are disposed in an area excluding protection area Z shown in FIG.

[0099] [Sixth embodiment] In the fourth and fifth embodiments, the pump drive signal wiring 611 is arranged only on the mounting surface 503. In contrast, in the sixth embodiment, as shown in Fig. 16, the pump drive signal wiring 611 is arranged not only on the mounting surface 503 but also on the pad surface 502. In Fig. 16, 611e and 611g indicate pump drive signal wiring arranged on the mounting surface 503, and 611f indicates pump drive signal wiring arranged on the pad surface. The pump drive signal wiring 611e arranged on the mounting surface 503 and the pump drive signal wiring 611f arranged on the pad surface 502 are connected by a through-hole 607r. The pump drive signal wiring 611g arranged on the mounting surface 503 and the pump drive signal wiring 611f arranged on the pad surface 502 are connected by a through-hole 607s.

[0100] 16, a protection area Z is provided around the pump drive signal wiring 611f on the pad surface 502. The protection area Z provided on the pad surface 502 is a set of points excluding any points that are more than a distance D away from any point on the pump drive signal wiring 611f. The protection area Z provided on the pad surface 502 can also be said to be a set of points Q2 that are less than or equal to the distance D from at least one point Q1 on the pump drive signal wiring 611f.

[0101] When wiring is arranged on the pad surface 502, the same rules as in the first embodiment are applied to the protection area Z provided on the pad surface 502. For example, the ejection element drive signal wiring (differential) 618 and the ejection element output wiring (analog) 621 are arranged in an area excluding the protection area Z. Furthermore, the EEPROM setting signal wiring 616, heater power supply wiring 620, and logic power supply wiring 622 are arranged in an area excluding the protection area Z, or are arranged in the protection area Z after connecting a short-circuit protection circuit. The ejection element drive signal wiring (non-differential) 623, ejection element output wiring (digital) 624, and IC control signal wiring 625 are also arranged in an area excluding the protection area Z, or are arranged in the protection area Z after connecting a short-circuit protection circuit.

[0102] In the example of FIG. 16, all pads and corresponding through holes (not shown) are arranged in the area excluding the protection area Z.

[0103] [Seventh embodiment] As shown in Fig. 17, the electric circuit board 205 according to the seventh embodiment is obtained by reducing the number of switching circuits 602 from two to one in the electric circuit board 205 shown in Fig. 6. The single switching circuit 602 shown in Fig. 17 outputs a complementary pair of switched pump drive signal wirings. In other words, the single switching circuit 602 shown in Fig. 17 has a combined function of the pair of switching circuits 602 shown in Fig. 6. In the electric circuit boards 205 shown in Figs. 10 to 16, the pair of switching circuits 602 may also be changed to a single switching circuit 602 having a combined function.

[0104] [Eighth embodiment] 16, the boost circuit 601, the switching circuit 602, and the pump drive signal wiring 611 are disposed only on the mounting surface 503. In addition, as shown in FIGS. 2 and 5, the mounting surface 503 faces the outer surface of the flow path member 202.

[0105] The eighth embodiment employs the above-described configuration. Furthermore, in the seventh embodiment, a glass epoxy material (FR-4 board or FR-5 board) is used as the material for core material 803 (see FIG. 8) of electric circuit board 205 so as to achieve V-0 grade in the UL94 flame retardancy standard. Furthermore, the thickness of electric circuit board 205 is set to 1.7 mm. Therefore, even if smoke or fire were to occur starting near boost circuit 601, the smoke or flames would be contained by mounting surface 503 and electric circuit board 205, preventing the fire from spreading.

[0106] [Other embodiments] In the above embodiment, a Zener diode or a varistor is used as the short protection circuit. By inserting a Zener diode or a varistor between the target wiring and ground, it becomes possible to prevent the pump drive voltage from being applied to the target wiring even if the pump drive signal wiring 611 is shorted to the target wiring.

[0107] However, this is not limited to this, and a fuse circuit may be inserted as a short-circuit protection circuit between the target wiring and the output terminal connected to the target wiring. Even if the pump drive signal wiring 611 is shorted to the target wiring, the fuse circuit will operate to protect the circuit having the output terminal. By setting the operating current of the fuse circuit low, even if a wiring other than the pump drive signal wiring 611 (e.g., a low-voltage wiring) is shorted to the target wiring, the fuse circuit will operate to protect the circuit having the output terminal. Similarly, a fuse circuit may be inserted as a short-circuit protection circuit between the target wiring and the input terminal connected to the target wiring.

[0108] In the above embodiment, it has been described that the protection region Z is provided below the bottom edges of the boost circuit 601 and the switching circuit 602 when viewed in the plan view of Fig. 6. However, although not described, a protection region is also provided above the bottom edges of the boost circuit 601 and the switching circuit 602. For example, a margin may be added so that the entire area above the bottom edges of the boost circuit 601 and the switching circuit 602 is added as a protection region.

[0109] In the above embodiment, a configuration in which multiple circulation pumps are driven by a common pump drive signal has been described as an example, but this is not limiting. For example, a pair of a boost circuit and a switching circuit may be disposed on an electric circuit board for each circulation pump, and each pair may drive a corresponding circulation pump.

[0110] In the above embodiment, the pump reference signal wiring 612 and the FPGA power supply wiring 615 are coupled to each other on the electric circuit board 205, and pads T20 and T12 are provided for each of them. However, the present invention is not limited to this. The pump reference signal wiring 612 and the FPGA power supply wiring 615 may be separated from each other on the electric circuit board 205. In this case, the FPGA power supply wiring 615 is disposed in an area excluding the protection area Z, and therefore there is no need to connect a short protection circuit to it.

[0111] In the above embodiment, the pair of switching circuits 602 is disposed on the electric circuit board 205, but the present disclosure is not limited to this. For example, the pair of switching circuits 602 may be disposed on an electric circuit board other than the electric circuit board 205.

[0112] A switching circuit 602 may be provided for each circulation pump corresponding to a different color. In the first embodiment, if the number of colors is four and a switching circuit 602 is provided for each color, the number of switching circuits will be eight. In the seventh embodiment, if the number of colors is four and a switching circuit 602 is provided for each color, the number of switching circuits will be four. In these configurations, for example, the number of boost circuit drive signal wirings 614 may be four, and the pump drive voltage may be controlled for each color.

[0113] <Technical Features of the Present Disclosure> The present disclosure includes the following configurations.

[0114] [Configuration 1] a boost circuit that generates a pump drive signal having a pump drive voltage for driving a circulation pump that circulates a liquid by boosting a pump reference signal having a reference voltage based on a boost circuit drive signal; a first wiring for transmitting the pump drive signal; a second wiring for transmitting the pump reference signal; a third wiring for transmitting the booster circuit drive signal; a plurality of fourth wirings for transmitting signals related to the ejection elements that eject liquid; Equipped with the second wiring and the third wiring have a portion disposed at a position closer than a protection distance from the first wiring, and are provided with a short circuit protection circuit; the plurality of fourth wirings include one or more first-type wirings arranged at a position that is farther away from the first wirings than the protection distance; Electrical circuit board.

[0115] [Configuration 2] at least one switching circuit for intermittently supplying the pump drive signal to the circulation pump based on a pump drive control signal; a fifth wiring for transmitting the pump drive control signal; the fifth wiring has a portion disposed at a position closer than the protection distance from the first wiring, and is provided with a short-circuit protection circuit; 2. The electric circuit board according to claim 1.

[0116] [Configuration 3] The first type wiring is Wiring for driving the energy conversion elements included in the ejection elements; wiring for transmitting an analog signal indicative of the temperature of the ejection element; Wiring for supplying a heater power supply voltage to the heater of the ejection element; a wiring for supplying a heater ground voltage corresponding to the heater power supply voltage to the heater of the ejection element; Wiring for transmitting a digital signal indicating the surface state of a heater electrode of an ejection module including the ejection element; Wiring for setting the EEPROM disposed on the electric circuit board; Wiring for supplying logic power to an energy conversion element included in the ejection module and a logic circuit mounted on the electric circuit board; IC control signal wiring, and an ejection element drive signal wiring for supplying a signal indicating a drive timing to an energy conversion element included in an ejection module including the ejection element by a method other than a differential transmission method; including at least one of 3. The electric circuit board according to claim 1 or 2.

[0117] [Configuration 4] the plurality of fourth wirings have a portion disposed at a position closer than the protection distance from the first wiring, and further include one or more second-type wirings to which a short-circuit protection circuit is attached; 4. The electric circuit board according to any one of configurations 1 to 3.

[0118] [Configuration 5] The second type of wiring is Wiring for supplying a heater power supply voltage to the heater of the ejection element; Wiring for transmitting a digital signal indicating the surface state of a heater electrode of an ejection module including the ejection element; Wiring for setting the EEPROM disposed on the electric circuit board; Wiring for supplying logic power to an energy conversion element included in the ejection module and a logic circuit mounted on the electric circuit board; IC control signal wiring, and an ejection element drive signal wiring for supplying a signal indicating a drive timing to an energy conversion element included in an ejection module including the ejection element by a method other than a differential transmission method; including at least one of 5. The electric circuit board according to claim 4.

[0119] [Configuration 6] the plurality of fourth wirings have a portion disposed at a position closer than the protection distance from the first wirings, and further include one or more third-type wirings to which no short-circuit protection circuit is attached; 6. The electric circuit board according to any one of configurations 1 to 5.

[0120] [Configuration 7] The third type of wiring is Logic ground wiring, Wiring for supplying a heater power supply voltage to the heater of the ejection element; a wiring for supplying a heater ground voltage corresponding to the heater power supply voltage to the heater of the ejection element; Wiring for transmitting a digital signal indicating the surface state of a heater electrode of an ejection module including the ejection element; and Wiring for setting the EEPROM disposed on the electric circuit board; including at least one of 7. The electric circuit board according to claim 6.

[0121] [Configuration 8] the first wiring is disposed on a first surface of the electric circuit board; a second surface opposite to the first surface, and an upper terminal corresponding to the upper substrate; the upper terminal is connected to a wiring disposed on the second surface and a wiring disposed on the first surface via a through hole; the through hole is disposed at a position that is farther away from the first wiring than the protection distance in a plan view of the electric circuit board. 8. The electric circuit board according to any one of configurations 1 to 7.

[0122] [Configuration 9] the upper terminal and the wiring disposed on the second surface are also disposed at a position farther away from the first wiring than the protection distance in a plan view of the electric circuit board. 9. The electric circuit board according to claim 8.

[0123] [Configuration 10] the first wiring is disposed on a first surface of the electric circuit board and a second surface opposite to the first surface, and providing upper terminals on the second surface corresponding to the upper substrate; the upper terminal is connected to a wiring disposed on the second surface and a wiring disposed on the first surface via a through hole; the through hole is disposed at a position away from the first wiring disposed on the first surface and the first wiring disposed on the second surface by a protection distance in a plan view of the electric circuit board. 8. The electric circuit board according to any one of configurations 1 to 7.

[0124] [Configuration 11] the upper terminal and the wiring arranged on the second surface are also arranged at positions that are farther away from the first wiring arranged on the first surface and the first wiring arranged on the second surface than the protection distance in a plan view of the electric circuit board. 11. The electric circuit board according to claim 10.

[0125] [Configuration 12] the first wiring is disposed on a first surface of the electric circuit board; a second surface opposite to the first surface, and an upper terminal corresponding to the upper substrate; the upper terminals are connected to second-surface wiring disposed on the second surface and first-surface wiring disposed on the first surface via through holes; the through hole is disposed at a position closer than the protection distance from the first wiring in a plan view of the electric circuit board, a short-circuit protection circuit is attached to the first surface wiring or the second surface wiring; 8. The electric circuit board according to any one of configurations 1 to 7.

[0126] [Configuration 13] On the second surface, the upper terminal and the second surface wiring are arranged in an area excluding a circular area having a center at the through hole and a radius obtained by subtracting the distance from the protection distance to the distance from the first wiring to the through hole and the thickness of the electric circuit board. 13. The electric circuit board according to claim 12.

[0127] [Configuration 14] the first wiring is disposed on a first surface of the electric circuit board; a second surface opposite to the first surface, and an upper terminal corresponding to the upper substrate; the upper terminals are connected to second-surface wiring disposed on the second surface and first-surface wiring disposed on the first surface via through holes; the through hole is disposed at a position farther from the first wiring than the protection distance in a plan view of the electric circuit board, The first surface wiring and the second surface wiring are not provided with a short circuit protection circuit. 8. The electric circuit board according to any one of configurations 1 to 7.

[0128] [Configuration 15] The short circuit protection circuit is activated when the wiring to which the short circuit protection circuit is attached is shorted with the first wiring. 15. The electric circuit board according to any one of configurations 1 to 14.

[0129] [Configuration 16] The short circuit protection circuit is activated when a wiring to which the short circuit protection circuit is attached is shorted to a wiring different from the first wiring. 15. The electric circuit board according to any one of configurations 1 to 14.

[0130] [Configuration 17] The protective distance is a distance that satisfies the conditions stipulated in IEC 60950-1 regarding clearance distance. 17. The electric circuit board according to any one of configurations 1 to 16.

[0131] [Configuration 18] the liquid circulation unit including the circulation pump and a liquid ejection head including a ejection unit having a plurality of the ejection elements that eject the liquid supplied from the liquid circulation unit; 18. The electric circuit board according to any one of configurations 1 to 17.

[0132] [Configuration 19] An electric circuit board according to any one of configurations 1 to 18; a liquid circulation unit including the circulation pump; a discharge unit having a plurality of the discharge elements for discharging the liquid supplied from the liquid circulation unit; A liquid ejection head comprising:

[0133] [Configuration 20] the boost circuit and the first wiring are provided on a surface of the electric circuit board facing an outer surface of a flow path member that houses the discharge unit, The electric circuit board satisfies the flame retardancy standard UL94 V-0. 19. A liquid ejection head according to claim 19. [Explanation of symbols]

[0134] 205 Electrical Circuit Board 601 Booster Circuit 602 Switching circuit 611 Pump drive signal wiring 612 Pump reference signal wiring 613 Pump drive control signal wiring 614 Boost circuit drive signal wiring 618 Ejection element drive signal wiring (differential) 621 Ejection element output wiring (analog)

Claims

1. a boost circuit that generates a pump drive signal having a pump drive voltage for driving a circulation pump that circulates a liquid by boosting a pump reference signal having a reference voltage based on a boost circuit drive signal; a first wiring for transmitting the pump drive signal; a second wiring for transmitting the pump reference signal; a third wiring for transmitting the booster circuit drive signal; a plurality of fourth wirings for transmitting signals related to the ejection elements that eject liquid; Equipped with the second wiring and the third wiring have a portion disposed at a position closer than a protection distance from the first wiring, and are provided with a short-circuit protection circuit; the plurality of fourth wirings include one or more first-type wirings arranged at a position that is farther away from the first wirings than the protection distance; Electrical circuit board.

2. at least one switching circuit for intermittently supplying the pump drive signal to the circulation pump based on a pump drive control signal; a fifth wiring for transmitting the pump drive control signal; the fifth wiring has a portion disposed at a position closer than the protection distance from the first wiring, and is provided with a short-circuit protection circuit; 2. The electric circuit board according to claim 1.

3. The first type wiring is Wiring for driving the energy conversion elements included in the ejection elements; wiring for transmitting an analog signal indicative of the temperature of the ejection element; Wiring for supplying a heater power supply voltage to the heater of the ejection element; a wiring for supplying a heater ground voltage corresponding to the heater power supply voltage to the heater of the ejection element; Wiring for transmitting a digital signal indicating the surface state of a heater electrode of an ejection module including the ejection element; Wiring for setting the EEPROM disposed on the electric circuit board; Wiring for supplying logic power to an energy conversion element included in the ejection module and a logic circuit mounted on the electric circuit board; IC control signal wiring, and an ejection element drive signal wiring for supplying a signal indicating a drive timing to an energy conversion element included in an ejection module including the ejection element by a method other than a differential transmission method; At least one of the following is included:

2. The electric circuit board according to claim 1.

4. the plurality of fourth wirings have a portion disposed at a position closer than the protection distance from the first wiring, and further include one or more second-type wirings to which a short-circuit protection circuit is attached; 2. The electric circuit board according to claim 1.

5. The second type of wiring is Wiring for supplying a heater power supply voltage to the heater of the ejection element; Wiring for transmitting a digital signal indicating the surface state of a heater electrode of an ejection module including the ejection element; Wiring for setting the EEPROM disposed on the electric circuit board; Wiring for supplying logic power to an energy conversion element included in the ejection module and a logic circuit mounted on the electric circuit board; IC control signal wiring, and an ejection element drive signal wiring for supplying a signal indicating a drive timing to an energy conversion element included in an ejection module including the ejection element by a method other than a differential transmission method; At least one of the following is included:

5. The electric circuit board according to claim 4.

6. the plurality of fourth wirings have a portion disposed at a position closer than the protection distance from the first wiring, and further include one or more third-type wirings to which no short-circuit protection circuit is attached; 2. The electric circuit board according to claim 1.

7. The third type of wiring is Logic ground wiring, Wiring for supplying a heater power supply voltage to the heater of the ejection element; a wiring for supplying a heater ground voltage corresponding to the heater power supply voltage to the heater of the ejection element; Wiring for transmitting a digital signal indicating the surface state of a heater electrode of an ejection module including the ejection element; and Wiring for setting the EEPROM disposed on the electric circuit board; At least one of the following is included:

7. The electric circuit board according to claim 6.

8. the first wiring is disposed on a first surface of the electric circuit board; a second surface opposite to the first surface, and an upper terminal corresponding to the upper substrate; the upper terminal is connected to a wiring disposed on the second surface and a wiring disposed on the first surface by a through hole; the through hole is disposed at a position that is farther away from the first wiring than the protection distance in a plan view of the electric circuit board; 2. The electric circuit board according to claim 1.

9. the upper terminal and the wiring disposed on the second surface are also disposed at a position away from the first wiring by the protection distance in a plan view of the electric circuit board.

9. The electric circuit board according to claim 8.

10. the first wiring is disposed on a first surface of the electric circuit board and a second surface opposite to the first surface, an upper terminal corresponding to an upper substrate is provided on the second surface; the upper terminal is connected to a wiring disposed on the second surface and a wiring disposed on the first surface by a through hole; the through hole is disposed at a position away from the first wiring disposed on the first surface and the first wiring disposed on the second surface by a protection distance in a plan view of the electric circuit board; 2. The electric circuit board according to claim 1.

11. the upper terminal and the wiring disposed on the second surface are also disposed at positions that are farther away from the first wiring disposed on the first surface and the first wiring disposed on the second surface than the protection distance in a plan view of the electric circuit board; 11. The electrical circuit board according to claim 10.

12. the first wiring is disposed on a first surface of the electric circuit board; a second surface opposite to the first surface, and an upper terminal corresponding to the upper substrate; the upper terminals are connected to second-surface wiring disposed on the second surface and first-surface wiring disposed on the first surface via through holes; the through hole is disposed at a position closer than the protection distance from the first wiring in a plan view of the electric circuit board, a short-circuit protection circuit is attached to the first surface wiring or the second surface wiring; 2. The electric circuit board according to claim 1.

13. on the second surface, the upper terminal and the second surface wiring are arranged in an area excluding a circular area having a center at the through hole and a radius obtained by subtracting the distance from the protection distance to the distance from the first wiring to the through hole and the thickness of the electric circuit board, 13. The electrical circuit board of claim 12.

14. the first wiring is disposed on a first surface of the electric circuit board; a second surface opposite to the first surface, and an upper terminal corresponding to the upper substrate; the upper terminals are connected to second-surface wiring disposed on the second surface and first-surface wiring disposed on the first surface via through holes; the through hole is disposed at a position farther from the first wiring than the protection distance in a plan view of the electric circuit board, The first surface wiring and the second surface wiring are not provided with a short circuit protection circuit.

2. The electric circuit board according to claim 1.

15. The short circuit protection circuit is activated when a wiring to which the short circuit protection circuit is attached is shorted to the first wiring.

15. The electric circuit board according to claim 1.

16. The short circuit protection circuit is activated when a wiring to which the short circuit protection circuit is attached is shorted to a wiring different from the first wiring.

15. The electric circuit board according to claim 1.

17. The protection distance is a distance that satisfies the conditions stipulated in IEC 60950-1 regarding clearance distance.

15. The electric circuit board according to claim 1.

18. the liquid circulation unit including the circulation pump and a liquid ejection head including a ejection unit having a plurality of the ejection elements that eject the liquid supplied from the liquid circulation unit; 15. The electric circuit board according to claim 1.

19. An electric circuit board according to any one of claims 1 to 14; a liquid circulation unit including the circulation pump; a discharge unit having a plurality of the discharge elements for discharging the liquid supplied from the liquid circulation unit; A liquid ejection head comprising:

20. the boost circuit and the first wiring are provided on a surface of the electric circuit board facing an outer surface of a flow path member that houses the discharge unit, The electric circuit board satisfies the flame retardancy standard UL94 V-0.

20. The liquid ejection head according to claim 19.

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