Liquid leakage detecting device and ink jet recording apparatus

Abstract

To improve space efficiency inside an ink jet recorder.SOLUTION: A liquid leakage detection device provided inside an ink jet recording apparatus includes a first substrate provided with a pair of electrode terminals as a first ink detection unit, a second substrate provided with another pair of electrode terminals as a second ink detection unit, and a control substrate provided with a detection circuit that detects leakage of a liquid. The first board, the second board, and the control board are electrically connected in series in this order, and the first board is not directly electrically connected to the control board. The detection circuit detects that the liquid has leaked by detecting a short circuit between the pair of electrode terminals or a short circuit between another pair of electrode terminals via the second substrate.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a liquid leakage detection device and an inkjet recording device. [Background technology]

[0002] Patent Document 1 describes a technology for an ink leak detection mechanism for a printer. In the technology described in Patent Document 1, a pair of electrode terminals functions as an ink detection unit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-160825 Summary of the Invention [Problem to be solved by the invention]

[0004] To improve the accuracy of ink leak detection, ink detection units are installed in multiple locations inside the printer where ink leaks are likely to occur. Conventionally, the ink detection units and the control unit are individually connected by wires. This creates the problem that the wires connecting the ink detection units and the control unit take up a large amount of space in the limited space inside the printer. For this reason, there is a need for improved space efficiency inside the printer. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] According to one aspect of the present disclosure, there is provided a liquid leakage detection device to be installed inside an inkjet recording apparatus. The liquid leakage detection device includes a first substrate having a pair of electrode terminals as a first ink detection unit, a second substrate having another pair of electrode terminals as a second ink detection unit, and a control substrate having a detection circuit that detects liquid leakage. The first substrate, the second substrate, and the control substrate are electrically connected in series in this order, and the first substrate is not electrically connected directly to the control substrate. The detection circuit detects liquid leakage by detecting, via the second substrate, that the potential difference between the pair of electrode terminals or the other pair of electrode terminals has fallen below a predetermined threshold.

[0007] According to another aspect of the present disclosure, there is provided an inkjet recording device. The inkjet recording device includes a liquid circulation unit, an ejection unit, a case storage unit, a control unit, and a liquid leakage detection device. The liquid leakage detection device includes a first substrate having a pair of electrode terminals as a first ink detection unit, a second substrate having another pair of electrode terminals as a second ink detection unit, and a control substrate having a detection circuit that detects liquid leakage. The first substrate, the second substrate, and the control substrate are electrically connected in series in this order, and the first substrate is not directly electrically connected to the control substrate. The detection circuit detects liquid leakage by detecting, via the second substrate, that the potential difference between the pair of electrode terminals or the other pair of electrode terminals has fallen below a predetermined threshold. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic perspective view showing the external configuration of a printing device equipped with a liquid leakage detection device according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of the printing device as seen from the +Y direction side. [Figure 3] FIG. 2 is an explanatory diagram showing the circuit configuration of the liquid leakage detection device. [Figure 4]3 is an explanatory diagram showing a schematic configuration of wiring on a first substrate and a second substrate and an ink detection unit. FIG. [Figure 5] FIG. 10 is an explanatory diagram of a method for detecting the occurrence of ink leakage. [Figure 6] 10A and 10B are explanatory diagrams of a method for detecting a conduction failure with a substrate. [Figure 7] 10A and 10B are diagrams illustrating another method for detecting a conduction failure with a substrate. [Figure 8] FIG. 3 is an explanatory diagram showing the arrangement of electrode terminals on the first substrate and the second substrate. [Figure 9] 9 is an explanatory diagram of the first substrate and the second substrate when viewed from the opposite side to that of FIG. 8. FIG. [Figure 10] FIG. 10 is an explanatory diagram showing an example of the arrangement of substrates in the second embodiment. [Figure 11] FIG. 10 is an explanatory diagram showing an example of the arrangement of substrates in the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. First embodiment: FIG. 1 is a schematic perspective view showing the external configuration of a printing device 10 equipped with a liquid leakage detection device 70 according to this embodiment. An XYZ Cartesian coordinate system is set up in FIG. 1. The Z axis is aligned with the direction of gravity. The +Z direction is the direction of gravity. The Z direction corresponds to the up-down direction of the printing device 10. The X and Y axes are aligned with the horizontal plane. The Y axis is aligned with the front-to-rear direction of the printing device 10. The +Y direction corresponds to the direction from the rear to the front of the printing device 10. The X axis is aligned with the left-to-right direction of the printing device 10. The +X direction corresponds to the direction from right to left when facing the front of the printing device 10. FIG. 2 is a schematic view of the printing device 10 viewed from the +Y direction with the housing 10h and cover member 18 removed.

[0010] The printing device 10 includes a housing 10h, a liquid circulation unit 20 arranged within the housing 10h, a jetting unit 30, a medium transport unit 35, a control unit 40, and a liquid leakage detection device 70. Note that the liquid circulation unit 20, the jetting unit 30, the medium transport unit 35, the control unit 40, and the liquid leakage detection device 70 are not shown in Fig. 1. The liquid leakage detection device 70 is not shown in Fig. 2.

[0011] The printing device 10 is an inkjet printer. The printing device 10 is also called an "inkjet recording device." The printing device 10 forms an image by ejecting ink, which is an example of a liquid, and recording ink dots on a medium, such as printing paper. The medium onto which the printing device 10 ejects ink is not limited to printing paper, but may also be plastic, film, fiber, fabric, leather, metal, glass, wood, ceramics, etc.

[0012] 1, the housing 10h is a hollow, approximately rectangular parallelepiped enclosure that constitutes the exterior of the printing device 10. A front surface 12 of the housing 10h is provided with an operation panel 13, a medium discharge port 14, a paper discharge tray 15, a paper feed tray 16, an attachment port 17, a cover member 18, and a case storage section 19.

[0013] The operation panel 13 functions as a display unit that displays information and an input unit that accepts user operations. The operation panel 13 is, for example, a touch panel. The medium discharge port 14 is an exit for media discharged from the interior of the printing device 10. The medium discharge port 14 is formed as a slit-shaped opening that is wide in the X direction. The paper discharge tray 15 is located below the medium discharge port 14. The paper discharge tray 15 receives media discharged from the medium discharge port 14.

[0014] The paper feed tray 16 stores media. The loading slot 17 is an opening for inserting the paper feed tray 16 into the housing 10h. The loading slot 17 is formed below the paper output tray 15 as a generally rectangular opening that is wide in the X direction. When replenishing media, the user places the media in the paper feed tray 16 that has been pulled out from the loading slot 17 in the +Y direction. The user then loads the paper feed tray 16 into the printing device 10 through the loading slot 17.

[0015] The cover member 18 is a plate-like member made of resin that forms part of the exterior of the printing device 10. The cover member 18 has a generally rectangular shape that is wide in the X direction. The cover member 18 is disposed below the paper feed tray 16. The cover member 18 has claws (not shown) on its outer periphery and is detachably attached to the housing 10h. The cover member 18 covers the cases S1 to S4 stored in the case storage section 19.

[0016] The case storage section 19 is a space formed inside the housing 10h for storing the cases S1 to S4. The cases S1 to S4 are configured as tray-shaped containers. The cases S1 to S4 are used to mount the ink cartridges IC1 to IC4 in the printing device 10. The cases S1 to S4 are arranged in the X direction in the case storage section 19. The cases S1 to S4 are mounted in the printing device 10 with the ink cartridges IC1 to IC4 housed inside. The ink cartridges IC1 to IC4 are so-called ink packs. The ink cartridges IC1 to IC4 store black, cyan, magenta, and yellow ink, respectively. When setting the ink cartridges, the user places the ink cartridges in the case that has been pulled out in the +Y direction. The user then inserts the case into the case storage section 19.

[0017] As shown in FIG. 2, the liquid circulation unit 20 includes a plurality of tubes 21, a plurality of circulation pipes 22, and a pump 25. The plurality of tubes 21 are arranged in the Y direction. The plurality of tubes 21 are connected to the print head 31. The plurality of tubes 21 are connected to a plurality of circulation pipes 22. When the pump 25 is operated, the ink inside the ink cartridges IC1 to IC4 is pushed out into the circulation pipes 22. The ink in the ink cartridges IC1 to IC4 is supplied to the print head 31 via the circulation pipes 22 and the tubes 21.

[0018] The ejection execution unit 30 includes a print head 31 and a carriage 34. The print head 31 receives ink supply via multiple tubes 21 of the liquid circulation unit 20. The print head 31 includes nozzles N that eject the ink supplied from the liquid circulation unit 20 downward. The print head 31 moves together with the carriage 34, and ejects ink supplied from ink cartridges IC1 to IC4 onto the medium. The carriage 34 carries the print head 31, and is moved back and forth in the X direction, which is the main scanning direction, by a drive mechanism (not shown).

[0019] The medium transport unit 35 transports the medium M in the sub-scanning direction under the control of the control unit 40. The sub-scanning direction is the Y direction. The medium transport unit 35 includes transport rollers 36 that are installed in the X direction below the print head 31. A paper feed tray 16 is disposed below the transport rollers 36.

[0020] When the printing process is executed, the control unit 40 causes the medium transport unit 35 to transport the medium M in the sub-scanning direction. Furthermore, the control unit 40 causes the carriage 34 to move the print head 31 back and forth in the main scanning direction along the transport roller 36 above the transport roller 36. The control unit 40 causes the print head 31 to eject ink droplets onto the printing surface of the medium M at timing determined based on the print data. Thus, ink dots are recorded on the medium M being transported by the medium transport unit 35 at positions determined based on the print data, and an image based on the print data is formed.

[0021] FIG. 3 is an explanatory diagram showing the circuit configuration of the liquid leakage detection device 70 provided inside the printing device 10. FIG. 4 is an explanatory diagram showing the wiring of the first substrate 100B and the second substrate 200B and the schematic configuration of the ink detection unit. The liquid leakage detection device 70 detects ink leakage inside the printing device 10. The liquid leakage detection device 70 has a first ink detection unit 100, a second ink detection unit 200, and a detection circuit 300.

[0022] The first ink detection unit 100 shown in FIG. 4 detects ink leakage inside the printing device 10. The first ink detection unit 100 is composed of a pair of electrode terminals provided on the first substrate 100B. The first substrate 100B is provided with wiring 110, wiring 120, wiring 130, electrode terminal 111, electrode terminal 121, connector CN, and resistor R0. The first substrate 100B is a printed circuit board. The wiring 110, 120, and 130 are formed by printing wiring conductors on the first substrate 100B. The wiring 110, 120, and 130 are arranged in parallel. The wiring 110, 120, and 130 are covered with a resist, which is a coating material. The electrode terminal 111 is formed by exposing a portion of the conductor portion of the wiring 110. The electrode terminal 121 is formed by exposing a portion of the conductor portion of the wiring 120. The electrode terminals 111 and 121 may be formed as pads by routing the wiring 110 and 120, respectively, within the first substrate 100B using through-holes or the like. The electrode terminals 111 and 121 function as the first ink detection unit 100. The wiring 110, 120, and 130 can be electrically connected to other wirings using a connector CN. The wiring 110 is also referred to as the "first wiring." The wiring 120 is also referred to as the "second wiring." The electrode terminals 111 and 121 are also referred to as a "pair of electrode terminals." Furthermore, one end of the wiring 120 and one end of the wiring 130 are electrically connected using a 0 ohm resistor R0. The first ink detection unit 100 is disposed, for example, below the portion of the case storage unit 19 (see FIG. 2) that connects the case S1 and the liquid flow unit 20. At this time, the first ink detection unit 100 is disposed so that the electrode terminals 111 and 121 face the bottom surface of the case storage unit 19.

[0023] As shown in FIG. 4, the second ink detection unit 200 detects ink leakage inside the printing device 10. The second ink detection unit 200 is configured with a pair of electrode terminals provided on the second substrate 200B. The second substrate 200B is provided with wiring 210, wiring 220, wiring 230, electrode terminals 211 and 221, and two connectors CN. The second substrate 200B is a printed circuit board. The wiring 210, 220, and 230 are formed by printing wiring conductors on the second substrate 200B. The wiring 210, 220, and 230 are arranged in parallel. The wiring 210, 220, and 230 are covered with a resist coating material. The electrode terminal 211 is formed by exposing a portion of the conductor portion of the wiring 210. The electrode terminal 221 is formed by exposing a portion of the conductor portion of the wiring 220. The electrode terminals 211 and 221 may be formed as pads by routing the wirings 210 and 220, respectively, within the second substrate 200B using through holes or the like. The electrode terminals 211 and 221 function as the second ink detection unit 200. The wirings 210, 220, and 230 can be electrically connected to other wirings by a connector CN. The wiring 210 is also referred to as the "third wiring." The wiring 220 is also referred to as the "fourth wiring." The electrode terminals 211 and 221 are also referred to as the "other pair of electrode terminals."

[0024] The second ink detection unit 200 is disposed, for example, in the case storage unit 19 (see FIG. 2) below the portion that connects the case S2 and the liquid circulation unit 20. In this case, the second ink detection unit 200 is disposed so that the electrode terminals 211 and 221 face the bottom surface of the case storage unit 19.

[0025] As shown in Fig. 4, the first substrate 100B and the second substrate 200B are connected via a cable F1. The second substrate 200B and the control substrate 300B are connected via a cable F2. The cables F1 and F2 are multi-core flat cables. The control substrate 300B is disposed inside the control unit 40, for example.

[0026] 3 detects ink leakage inside the printing device 10 by detecting a short circuit between the electrode terminals 111 and 121 or a short circuit between the electrode terminals 211 and 221. Because ink is a conductor, if ink leaks near the electrode terminals 111 and 121, the ink will short circuit the terminals of the electrode terminals 111 and 121. The same applies to a short circuit between the terminals of the electrode terminals 131 and 141. The detection circuit 300 is provided on the control board 300B.

[0027] The detection circuit 300 includes a leakage signal terminal 301, a ground terminal 302, a link signal terminal 303, a first pull-up resistor 304, a second pull-up resistor 305, a comparator 306, a resistor R1, a capacitor C1, a power supply Vdd1, and a power supply Vdd2.

[0028] One end of the first pull-up resistor 304 is connected to the leakage signal terminal 301. The leakage signal terminal 301 is connected to the wiring 210 of the second substrate 200B via a cable F2. The other end of the first pull-up resistor 304 is connected to a power supply Vdd1. The potential of the power supply Vdd1 is set to the high-potential side of the signal potential. A constant voltage is applied to the leakage signal terminal 301 from the power supply Vdd1 via the first pull-up resistor 304. This fixes the potential of the leakage signal terminal 301. The leakage signal terminal 301 is connected to the positive input terminal of a comparator 306 via an RC circuit formed by a resistor R1 and a capacitor C1. The resistor R1 and the capacitor C1 are provided to output the time integral of the input to the leakage signal terminal 301 to the comparator 306. The ground terminal 302 is connected to the wiring 220 of the second substrate 200B via a cable F2. The ground terminal 302 is grounded.

[0029] A signal is input from the leakage signal terminal 301 to the positive input terminal of the comparator 306. The negative input terminal of the comparator 306 is signal grounded. The potential at the signal ground point is set as reference potential Vref1. The reference potential Vref1 is a low-potential potential and is an arbitrary voltage. The reference potential Vref1 is set to be lower than the voltage applied to the power supply Vdd1. When the potential of the signal input to the positive input terminal is lower than the reference potential Vref1, the comparator 306 outputs a Low signal as output Vink_leak. When the potential of the signal input to the positive input terminal (the signal input from the leakage signal terminal 301) is higher than the reference potential Vref1, the comparator 306 outputs a Hi signal as output Vink_leak. The output Vink_leak of the comparator 306 is input to a processor (not shown) equipped with an interface capable of accepting digital signals. The processor (not shown) is, for example, a processor that functions as the control unit 40.

[0030] One end of the second pull-up resistor 305 is connected to the link signal terminal 303. The link signal terminal 303 is connected to the wiring 230 of the second board 200B via a cable F2. The other end of the second pull-up resistor 305 is connected to a power supply Vdd2. A constant voltage is applied to the link signal terminal 303 from the power supply Vdd2 via the second pull-up resistor 305. This fixes the potential of the link signal terminal 303. The voltage applied from the power supply Vdd2 is set to be higher than the ground level.

[0031] The leakage signal terminal 301 of the detection circuit 300 is connected to one end of the wiring 210 of the second substrate 200B via a cable F2. The ground terminal 302 of the detection circuit 300 is connected to one end of the wiring 220 of the second substrate 200B via a cable F2. The other end of the wiring 210 of the second substrate 200B is connected to one end of the wiring 110 of the first substrate 100B via a cable F1. The other end of the wiring 210 is the end of the wiring 210 on the side that is not connected to the leakage signal terminal 301. The end of the wiring 210 includes, but is not limited to, an edge of the wiring 210. The other end of the wiring 220 of the second substrate 200B is connected to one end of the wiring 120 of the first substrate 100B via a cable F1. The other end of the wiring 220 is the end of the wiring 220 on the side that is not connected to the ground terminal 302. The end of the wiring 220 includes the edge of the wiring 220, but is not limited to the edge of the wiring 220.

[0032] In this way, the first substrate 100B, the second substrate 200B, and the control substrate 300B are connected in series in this order. The first substrate 100B is not electrically connected directly to the control substrate 300B. "Directly electrically connected" means that they are connected using a cable, harness, etc., without going through any other components.

[0033] Furthermore, the link signal terminal 303 of the detection circuit 300 is connected to one end of the wiring 230 of the second substrate 200B via a cable F2. The other end of the wiring 230 of the second substrate 200B is connected to one end of the wiring 130 of the first substrate 100B via a cable F1. Furthermore, as described above, the other end of the wiring 120 and the other end of the wiring 130 are electrically connected using a 0 ohm resistance R0. The other end of the wiring 120 is the end of the wiring 120 that is not connected to the wiring 220. The end of the wiring 120 includes, but is not limited to, the edge of the wiring 120. The other end of the wiring 130 is the end of the wiring 130 that is not connected to the wiring 230. The end of the wiring 130 includes, but is not limited to, the edge of the wiring 130. In this way, the wiring 230, the wiring 130, the wiring 120, and the wiring 220 are electrically connected in series in this order. The wiring 230, the wiring 130, the wiring 120, and the wiring 220 form one current path. The wiring 130 is also called the "fifth wiring." The wiring 230 is also called the "sixth wiring."

[0034] 5 is an explanatory diagram of a method for detecting ink leakage. Here, it is assumed that ink leakage has occurred near electrode terminals 211 and 221 of second substrate 200B. Ink leakage refers to ink leakage from inside ink cartridges IC1 to IC4, liquid circulation unit 20, etc.

[0035] If leaked ink shorts the electrode terminals 211 and 221 of the second substrate 200B, a short-circuit current It flows between the electrode terminals 211 and 221. This causes a voltage drop in the wiring 210, lowering the potential of the input signal to the positive input terminal of the comparator 306. When the potential of the input signal to the positive input terminal of the comparator 306 falls below the reference potential Vref1, the comparator 306 outputs a Low signal as the output Vink_leak. The fact that the potential of the input signal to the positive input terminal of the comparator 306 falls below the reference potential Vref1 indicates that both the potential difference between the electrode terminals 211 and 221 and the potential difference between the electrode terminals 111 and 121 fall below predefined thresholds. In this case, the comparator 306 outputs a Low signal as the output Vink_leak. In this way, ink leakage within the printing device 10 can be detected with a simple configuration. A processor (not shown) that receives a Low signal as the output Vink_leak can detect that an ink leak has occurred on either the first substrate 100B or the second substrate 200B. Furthermore, for example, the processor (not shown) can notify the user that an ink leak has been detected.

[0036] Figure 5 shows an example in which ink leakage occurs near electrode terminals 211 and 221 of second substrate 200B, but if a short circuit occurs between electrode terminals 111 and 121 of first substrate 100B due to leaked ink, a voltage drop will similarly occur and comparator 306 will output a Low signal as output Vink_leak.

[0037] In this embodiment, the first substrate 100B, the second substrate 200B, and the control substrate 300B are electrically connected in series in this order, and the first substrate 100B is not electrically connected directly to the control substrate 300B. This reduces the space occupied by the wiring connecting the substrates within the printing device 10 compared to when the first substrate 100B is electrically connected directly to the control substrate 300B and the second substrate 200B is electrically connected directly to the control substrate 300B. This improves the space efficiency within the printing device 10. Furthermore, by adjusting the cable length, it is easy to space-apart the substrates on which the ink detection units are provided. Furthermore, the simple configuration of the liquid leakage detection device 70 makes it easy to install the liquid leakage detection device 70 in various models of printing devices. Even when there are multiple substrates on which ink detection units are provided, the control substrate 300B only needs to receive signals from any of the multiple substrates, thereby avoiding strain on the communication resources on the control substrate 300B side.

[0038] FIG. 6 is an explanatory diagram illustrating other functions of the detection circuit 300 in addition to its function of detecting ink leakage. In this embodiment, the detection circuit 300 detects a continuity failure with one or more of the multiple substrates connected to the control substrate 300B. In a conventional configuration in which the first substrate 100B is electrically connected directly to the control substrate 300B and the second substrate 200B is electrically connected directly to the control substrate 300B, the detection circuit 300 can determine whether or not the substrate on which the ink detection unit is provided is electrically connected based on, for example, the presence or absence of a signal from each ink detection unit. However, in this embodiment, the first substrate 100B is not directly connected to the control substrate 300B. Therefore, a continuity failure with one or more substrates is detected using a single current path formed by the wiring 230, wiring 130, wiring 120, and wiring 220. A continuity failure refers to a state in which there is no continuity with one of the substrates, for example, due to a cable being disconnected from a connector. To facilitate understanding of the technology, it is assumed that no ink leakage occurs.

[0039] As shown in Figure 6, wiring 230, wiring 130, wiring 120, and wiring 220 are connected in series. Ground terminal 302, which is connected to one end of wiring 220, is grounded. One end of wiring 230 is connected to link signal terminal 303. A signal input to link signal terminal 303 is input as output Vlink to a processor (not shown) that has an interface capable of accepting digital signals. When one current path formed by wiring 230, wiring 130, wiring 120, and wiring 220 is conductive, the potential of the signal input to link signal terminal 303 is at ground level. Therefore, the potential of the signal output as output Vlink is at ground level.

[0040] As shown in Figure 7, if the cable F1 connecting the first board 100B and the second board 200B becomes disconnected from the connector on either the first board 100B or the second board 200B, one of the current paths described above becomes non-conductive. In this case, the potential of the signal output as output Vlink rises and becomes equal to the output voltage of power supply Vdd2. The change in output Vlink allows a processor (not shown) to detect a continuity failure between the first board 100B or the second board 200B connected to the control board 300B.

[0041] In this manner, in this embodiment, it is possible to easily detect a continuity failure with one or more of the multiple boards connected to the control board 300B. If the cable becomes disconnected from the connector, it will also be impossible to detect ink leakage. Therefore, if the detection circuit 300 detects a continuity failure, a processor (not shown) can notify the user of this fact. By sharing the wiring 110 and wiring 210 used to detect ink leakage for detecting continuity failure with the board, the number of wirings arranged on the first board 100B and the second board 200B can be reduced. Furthermore, the above-described continuity failure detection configuration is more useful when the number of boards connected to the control board 300B is increased.

[0042] Figures 8 and 9 are explanatory diagrams relating to the arrangement of the electrode terminals on the first substrate 100B and the second substrate 200B. Figure 9 is an explanatory diagram of the first substrate 100B and the second substrate 200B viewed from the opposite side to that of Figure 8. Figure 4 shows a schematic diagram of the relationship between the wiring and the electrode terminals on the first substrate 100B and the second substrate 200B, but in actual use, it is preferable to arrange the electrode terminals as shown in Figures 8 and 9.

[0043] In the illustrated example, the liquid leakage detection device 70 has a first ink detection unit 100, a second ink detection unit 200, a detection circuit 300, and a liquid absorbing unit 400. The detection circuit 300 is not shown in Figures 8 and 9.

[0044] The first ink detection unit 100 is composed of a pair of electrode terminals provided on the first substrate 100B. As shown in FIGS. 8 and 9, the first substrate 100B is a printed circuit board formed in a rectangular shape. In this embodiment, the longitudinal direction of the first substrate 100B is defined as the left-right direction LR1 of the first substrate 100B. The left-right direction LR1 of the first substrate 100B is also referred to as the "first direction." The direction intersecting the longitudinal direction of the first substrate 100B, i.e., the short-side direction of the first substrate 100B, is defined as the up-down direction UD1 of the first substrate. The first substrate 100B is provided with electrode terminals 111 and 121 and a connector CN101. The connector CN101 electrically connects the electrode terminals 111 and 112 to other wiring, etc.

[0045] As shown in FIG. 9, the electrode terminals 111 and 121 are arranged on the surface DS100 of the first substrate 100B, side by side in the left-right direction LR1. The electrode terminals 111 and 121 are arranged so as to at least partially overlap with a virtual center line VL1, which is an imaginary straight line parallel to the long sides of the first substrate 100B. In other words, the electrode terminals 111 and 121 are arranged side by side in the direction in which the virtual center line VL extends. In FIG. 9, the virtual center line VL1, which is parallel to the long sides of the first substrate 100B, is represented by a dashed dotted line. The virtual center line VL1 is arranged at the center in the short-side direction of the first substrate 100B. The electrode terminals 111 and 121 are arranged near the center in the up-down direction UD1 of the first substrate 100B. Furthermore, the electrode terminals 111 and 121 are preferably arranged symmetrically both vertically and horizontally on the surface DS100 of the first substrate 100B. The electrode terminals 111 and 121 are composed of two pads formed on the surface DS. The surface DS100 on which the electrode terminals 111 and 121 are provided is also referred to as the "first surface." The imaginary center line VL1 set on the first substrate 100B is also referred to as the "first imaginary center line." As shown in FIG. 8, the connector CN101 is provided on the surface NS100 of the first substrate 100B. The surface NS100 is the opposite surface to the surface DS100.

[0046] The second ink detection unit 200 is composed of a pair of electrode terminals provided on the second substrate 200B. The second substrate 200B is a printed circuit board formed in a rectangular shape. In this embodiment, the longitudinal direction of the second substrate 200B is defined as the left-right direction LR2 of the second substrate 200B. The left-right direction LR2 of the second substrate 200B is also referred to as the "second direction." The direction intersecting the longitudinal direction of the second substrate 200B, i.e., the short-side direction of the second substrate 200B, is defined as the up-down direction UD2 of the second substrate. The second substrate 200B is provided with electrode terminals 211 and 221 and connectors CN201 and CN202. The electrode terminals 211 and 212 are electrically connected to other wiring, etc., via the connectors CN201 and CN202.

[0047] As shown in FIG. 9 , the electrode terminals 211 and 221 are arranged on the surface DS200 of the second substrate 200B, side by side in the left-right direction LR2. The electrode terminals 211 and 221 are arranged so as to at least partially overlap with the imaginary center line VL2. The imaginary center line VL2 is parallel to the long sides of the second substrate 200B and is arranged at the center of the second substrate 200B in the short direction. In other words, the electrode terminals 211 and 221 are arranged near the center of the second substrate 200B in the up-down direction UD2. In this embodiment, the imaginary center line VL1 and the imaginary center line VL2 are continuous. Furthermore, the electrode terminals 211 and 221 are preferably arranged symmetrically in the up-down direction and the left-right direction on the surface DS200 of the second substrate 200B. The electrode terminals 211 and 221 are formed by two pads formed on the surface DS. The surface DS200 on which the electrode terminals 211 and 221 are provided is also referred to as the "second surface." The virtual center line VL2 set on the second substrate 200B is also called a "second virtual center line."

[0048] 8, the connectors CN201 and CN202 are provided on a surface NS200 of the second substrate 200B. The surface NS200 is the surface opposite to the surface DS200.

[0049] 8, the connector CN101 of the first substrate 100B and the connector CN201 of the second substrate 200B are connected via a cable F1 (see FIG. 4). Thus, the first substrate 100B and the second substrate 200B are electrically connected.

[0050] The connector CN202 of the second substrate 200B and the leakage signal terminal 301 of the control substrate 300B are connected via a cable F2 (see FIG. 4). The connector CN202 of the second substrate 200B and the ground terminal 302 of the control substrate 300B are connected via a cable F2. Thus, the second substrate 200B and the control substrate 300B are electrically connected.

[0051] The liquid absorbing section 400 absorbs ink that leaks inside the printing device 10. The liquid absorbing section 400 is a strip-shaped porous or foamed material that has water absorption properties. For example, Belleater (registered trademark), Bemliese (registered trademark), or Sofras (registered trademark) can be used as the liquid absorbing section 400.

[0052] The liquid absorbing unit 400 is disposed below the first substrate 100B and the second substrate 200B in the direction of gravity. For example, the first ink detection unit 100 and the second ink detection unit 200 are disposed inside the case housing 19. In this case, the liquid absorbing unit 400 is disposed on the bottom surface of the case housing 19, and the first substrate 100B and the second substrate 200B are disposed on top of the liquid absorbing unit 400. The first substrate 100B is placed on the liquid absorbing unit 400 with the surface DS100 on which the electrode terminals 111 and 121 are provided facing the liquid absorbing unit 400 and the left-right direction LR1 of the first substrate 100B aligned with the longitudinal direction of the liquid absorbing unit 400. The second substrate 200B is placed on the liquid absorbing unit 400 with the surface DS200 on which the electrode terminals 211 and 221 are provided facing the liquid absorbing unit 400 and the left-right direction LR2 of the second substrate 200B aligned with the longitudinal direction of the liquid absorbing unit 400. Therefore, the electrode terminals 111 and 121 that constitute the first ink detection section 100 and the electrode terminals 211 and 221 that constitute the second ink detection section 200 come into contact with the liquid absorbing section 400.

[0053] For example, suppose that ink leakage occurs near the electrode terminals 111 and 121. The ink soaks into the liquid absorbing portion 400 and spreads. When the ink spreads to the area where the liquid absorbing portion 400 and the electrode terminals 111 and 121 are in contact, the ink shorts out the terminals of the electrode terminals 111 and 121. This short-circuiting between the terminals of the electrode terminals 111 and 121 causes the detection circuit 300 to detect that ink leakage has occurred.

[0054] The advantages of arranging the pair of electrode terminals near the center of the substrate in the up-down direction UD1 will be described below. Here, the first substrate 100B will be described as an example, but the second substrate 200B also has similar advantages.

[0055] The first substrate 100B is positioned as follows: The worker places the first substrate 100B on the liquid absorbing unit 400 so that the left-right direction LR1 of the first substrate 100B is aligned with the longitudinal direction of the liquid absorbing unit 400 and so that the vicinity of the center of the first substrate 100B in the up-down direction UD1 overlaps the vicinity of the center in the short-side direction (width direction) of the liquid absorbing unit 400. The same applies to the second substrate 200B.

[0056] Normally, a worker would need to be aware of the top and bottom of the second substrate 200B when placing it on the liquid absorbing unit 400. However, the second substrate 200B is rectangular, and the connectors CN201 and CN202 are symmetrically arranged on the surface NS200. This makes it difficult for the worker to distinguish between the top and bottom of the second substrate 200B. Therefore, it is conceivable that the worker might place the second substrate 200B upside down on the liquid absorbing unit 400. If the electrode terminals 211 and 221 are not located near the center of the second substrate 200B, a problem may occur in which one or both of the electrode terminals 211 and 221 are not in contact with the liquid absorbing unit 400 when the first substrate 100B is placed on the liquid absorbing unit 400.

[0057] In this embodiment, the electrode terminals 211 and 221 are arranged symmetrically in the upper and lower directions near the center of the second substrate 200B. Therefore, when the second substrate 200B is placed upside down on the liquid absorbing section 400, the electrode terminals 211 and 221 are not in their proper positions, but they come into contact with the liquid absorbing section 400. Therefore, if ink leakage occurs near the electrode terminals 211 and 221, the ink absorbed by the liquid absorbing section 400 will short-circuit the terminals of the electrode terminals 211 and 221. Therefore, the ink leakage detection function of the liquid leakage detection device 70 functions normally.

[0058] In the first substrate 100B, the connector CN101 may be disposed in the center in the left-right direction LR1. In such a case, even if the first substrate 100B is placed upside down on the liquid absorbing section 400, the electrode terminals 111 and 121 will not be in their proper positions, but will come into contact with the liquid absorbing section 400. Therefore, the ink leakage detection function will function normally.

[0059] The worker simply places the second substrate 200B on the liquid absorbing section 400 so that the left-right direction LR2 of the second substrate 200B is aligned with the longitudinal direction of the liquid absorbing section 400 and so that the center of the second substrate 200B in the up-down direction UD2 is aligned with the center of the width direction of the liquid absorbing section 400. This makes it easy to position the second substrate 200B.

[0060] In this embodiment, the liquid absorbing section 400 can be used in common for liquid leakage detection on the first substrate 100B and the second substrate 200B. Therefore, the liquid leakage detection device 70 can be configured more simply than in an embodiment in which a liquid absorbing section is provided on each substrate.

[0061] B. Second embodiment: In the first embodiment, an example has been described in which a pair of electrode terminals are arranged symmetrically near the center of the first substrate 100B and the second substrate 200B. However, the pair of electrode terminals does not have to be arranged symmetrically.

[0062] 10 is an explanatory diagram showing an example of the arrangement of substrates in the second embodiment. In this embodiment, the longitudinal direction of each substrate is set to the up-down direction, and the lateral direction of each substrate is set to the left-right direction.

[0063] The electrode terminals 111 and 121 are arranged on the surface DS100 side by side in the up-down direction UD1 of the first substrate 100B. The up-down direction UD1 of the first substrate 100B is also referred to as the "first direction." The electrode terminals 111 and 121 are arranged at the same distance from the center of the first substrate 100B in the up-down direction UD1. Unlike the second embodiment, the electrode terminals 111 and 121 are arranged closer to one end E1 of the first substrate 100B in the left-right direction LR1. In this way, the electrode terminals 111 and 121 are arranged symmetrically in the up-down direction and asymmetrically in the left-right direction on the surface DS100. The same applies to the electrode terminals 211 and 221 of the second substrate 200B.

[0064] In this embodiment, the first substrate 100B and the second substrate 200B are placed on the liquid absorbing unit 400 so that the vertical direction of each substrate, i.e., the longitudinal direction of each substrate, is aligned with the longitudinal direction of the liquid absorbing unit 400. The worker places the first substrate 100B on the liquid absorbing unit 400 so that one end E1 in the lateral direction of the first substrate 100B substantially overlaps one end E4 in the lateral direction (width direction) of the liquid absorbing unit 400. The same applies to the arrangement of the second substrate 200B. In this embodiment as well, the positioning of the first substrate 100B and the second substrate 200B is easy.

[0065] As in the first embodiment, the liquid absorbing section 400 can be used in common for liquid leakage detection on the first substrate 100B and the second substrate 200B. Therefore, the liquid leakage detection device 70 can be configured more simply than in an embodiment in which a liquid absorbing section is provided on each substrate.

[0066] C. Third embodiment: In the first embodiment, an example has been described in which a pair of electrode terminals is arranged vertically symmetrically near the center of the first substrate 100B and the second substrate 200B. However, the pair of electrode terminals does not have to be arranged vertically symmetrically.

[0067] FIG. 11 is an explanatory diagram showing an example of the arrangement of boards in the third embodiment. In this embodiment, the first board 100B, the third board 500B, and the second board 200B are connected in series in this order. Note that connectors are omitted from FIG. 11 for convenience. The configuration of the third board 500B is similar to that of the second board 200B. The electrode terminals 511 and 521 provided on the third board 500B function as ink detection units together with the first ink detection unit 100 and the second ink detection unit 200. In this embodiment, an example is described in which a recess is included in part of the side wall SW of the printing device 10 when viewed from above. As shown in FIG. 1, recesses are provided at the end of the +Z direction on the side wall SW of the housing 10h in the +X and −X directions. The recesses are formed in the housing 10h so that an operator can place their hands on them when carrying the printing device 10.

[0068] In this embodiment, as in the first embodiment, the longitudinal direction of the first substrate 100B is set as the left-right direction LR1 of the first substrate 100B, and the short-side direction of the first substrate 100B is set as the up-down direction UD1 of the first substrate. The longitudinal direction of the second substrate 200B is set as the left-right direction LR2 of the second substrate 200B, and the short-side direction of the second substrate 200B is set as the up-down direction UD2 of the second substrate. The longitudinal direction of the third substrate 500B is set as the left-right direction LR3 of the third substrate 500B, and the short-side direction of the third substrate 500B is set as the up-down direction UD3 of the third substrate.

[0069] In this embodiment, the electrode terminals 111 and 121 are arranged side by side in the left-right direction LR1 of the first substrate 100B. The left-right direction LR1 of the first substrate 100B is also referred to as the "first direction." The electrode terminals 111 and 121 are arranged close to one end E11 in the up-down direction UD1 of the first substrate 100B. The end E11 is one of the ends of the first substrate 100B in the up-down direction UD1, and is an end that is farther from the side wall portion SW than the other end. In this way, the electrode terminals 111 and 121 are arranged vertically asymmetrically and horizontally symmetrically on the surface DS100. The electrode terminals 211 and 221 of the second substrate 200B are arranged in the same manner as those of the first substrate 100B.

[0070] The electrode terminals 511 and 521 are arranged on the surface DS500 side by side in the left-right direction LR3 of the third substrate 500B. The electrode terminals 511 and 521 are arranged close to one end E51 in the up-down direction UD3 of the third substrate 500B. The end E51 is one of the ends of the third substrate 500B in the up-down direction UD3, and is an end closer to the side wall portion SW than the other end. The electrode terminals 511 and 521 are arranged asymmetrically in the up-down direction and symmetrically in the left-right direction on the surface DS500.

[0071] As shown in Fig. 11, each substrate is arranged so that the electrode terminals of each substrate are in contact with the liquid absorbing section 400. Furthermore, each substrate can be arranged to fit the shape of the side wall SW of the housing of the printing device 10, allowing for efficient use of the space within the printing device 10. Depending on the shape of the housing of the printing device 10, it may be convenient not to arrange the pair of electrode terminals in positions that are vertically and horizontally symmetrical with respect to the substrates, so that each substrate shares the liquid absorbing section 400. In such cases, the configuration according to this embodiment can be adopted.

[0072] In this embodiment as well, the liquid absorbing section 400 can be commonly used for liquid leakage detection on the first substrate 100B, the second substrate 200B, and the third substrate 500B. Therefore, the liquid leakage detection device 70 can be configured more simply than in an embodiment in which a liquid absorbing section is provided on each substrate.

[0073] In the example shown in FIG. 11, if the substrates are placed upside down, some of the electrode terminals may not be in contact with the liquid absorbing section 400. To prevent this problem, each substrate may be provided with a mark indicating the up or down direction of the substrate. Marks can be characters printed on the substrate, through holes formed in the substrate, or notches formed in the substrate. In the example shown in FIG. 11, the character CH indicating the up direction of the third substrate 500B is printed on the third substrate. Through holes HO indicating the up direction are formed in the first substrate 100B, second substrate 200B, and third substrate 500B. By providing the mark, the worker can easily identify the up and down directions of the substrates. This prevents the worker from placing the substrates upside down. The surface on which these marks are provided may be the surface DS100 on which the electrode terminals are placed, or the opposite surface NS100. Alternatively, the mark may be a part of the housing of the printing device 10 facing the surface DS100 or surface NS100.

[0074] D. Other Embodiments: (D1) In the first embodiment and other examples, the first substrate 100B and the second substrate 200B are connected in series to the control substrate 300B. However, three or more substrates, each equipped with an ink detection unit, may be connected in series. For example, four substrates, each equipped with an ink detection unit, may be connected in series for each of the ink cartridges IC1 to IC4, so that they are located near the connection between the ink cartridge and the liquid flow unit 20. In other words, one first substrate 100B and three second substrates 200B may be connected in series. In this case, as in the above embodiment, ink leakage can be easily detected. Furthermore, the number of substrates equipped with ink detection units can be increased or decreased depending on the number of locations where liquid leakage needs to be detected, providing a high degree of freedom in the placement of the liquid leakage detection device 70 within the printing device 10.

[0075] (D2) In the first embodiment, an example was described in which the liquid leakage detection device 70 is provided with a configuration for detecting poor conductivity with the substrate, but the liquid leakage detection device 70 does not have to be provided with a configuration for detecting poor conductivity including the wiring 130 of the first substrate 100B, the wiring 230 of the second substrate 200B, the power supply Vdd2, etc.

[0076] (D3) In the first embodiment, an example was described in which the comparator 306 was used to detect the occurrence of a short circuit between a pair of electrode terminals. Alternatively, an A / D converter may be used instead of the comparator 306.

[0077] (D4) In the first embodiment and the like, an example was described in which the first ink detection unit 100 and the second ink detection unit 200 were arranged below the part that connects the case and the liquid circulation unit 20, but this is not limited to this. The board on which the first ink detection unit 100 is provided and the board on which the second ink detection unit 200 is provided can be arranged, for example, around the print head 31, below the carriage 34, below the pump 25, etc.

[0078] (D5) In the first embodiment, an example has been described in which the wiring 120 and the wiring 130 are electrically connected using a resistance R0 of 0 ohms as shown in Fig. 4. However, the wiring 120 and the wiring 130 may be directly connected.

[0079] (D6) In the first embodiment, an example was described in which the electrode terminals 111 and 121 were arranged on the surface DS100 side by side in the left-right direction LR1 of the first substrate 100B. However, the electrode terminals 111 and 121 may also be arranged on the surface DS100 side by side in the up-down direction UD1 of the first substrate 100B. In this case, the up-down direction of the first substrate 100B is referred to as the "first direction." The same applies to the electrode terminals 211 and 221 arranged on the second substrate 200B. In this case, the up-down direction of the second substrate 200B is referred to as the "second direction."

[0080] (D7) As shown in FIG. 10, when the first substrate 100B and the second substrate 200B are placed on the liquid absorbing unit 400 so that the short-side direction of each substrate is aligned with the long-side direction of the liquid absorbing unit 400, the electrode terminals 111 and 121 do not need to be arranged symmetrically in the vertical direction on the first substrate 100B. In this case, the electrode terminals 111 and 121 are arranged asymmetrically in the vertical direction and asymmetrically in the horizontal direction on the surface DS. The same applies to the second substrate 200B. Even if the first substrate 100B and the second substrate 200B are placed on the liquid absorbing unit 400 with the substrates turned upside down, the electrode terminals will come into contact with the liquid absorbing unit 400. Therefore, the ink leakage detection function of the liquid leakage detection device 70 functions normally.

[0081] (D8) In the second and third embodiments, an example has been described in which the liquid absorbing unit 400 is disposed below the first substrate 100B and the second substrate 200B in the direction of gravity. However, the arrangement of the first substrate 100B, the second substrate 200B, and the liquid absorbing unit 400 is not limited to this.

[0082] For example, the liquid absorbing unit 400 may be disposed above the first substrate 100B and the second substrate 200B in the direction of gravity. In this case, each substrate is disposed with the surface on which the electrode terminals of each substrate are provided facing upward. Alternatively, the liquid absorbing unit 400 may be disposed along a side wall that constitutes part of the housing of the printing device 10, and the first substrate 100B and the second substrate 200B may be stacked on the liquid absorbing unit 400. In this case, each substrate is disposed with the surface on which the electrode terminals of each substrate are provided facing the liquid absorbing unit 400.

[0083] (D9) The shape of the substrate on which the pair of electrode terminals that function as the ink detection unit are provided is not limited to a rectangular shape. For example, the shape of the substrate may be a circle, an ellipse, a square, a trapezoid, or a polygon, such as a pentagon or hexagon.

[0084] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0085] E. Other forms: (1) According to one aspect of the present disclosure, there is provided a liquid leakage detection device installed inside an inkjet recording device. The liquid leakage detection device includes a first substrate having a pair of electrode terminals as a first ink detection unit, a second substrate having another pair of electrode terminals as a second ink detection unit, and a control substrate having a detection circuit that detects liquid leakage. The first substrate, the second substrate, and the control substrate are electrically connected in series in this order, and the first substrate is not electrically connected directly to the control substrate. The detection circuit detects liquid leakage by detecting, via the second substrate, that the potential difference between the pair of electrode terminals or the other pair of electrode terminals has fallen below a predetermined threshold. According to the above embodiment, the first substrate, the second substrate, and the control substrate are electrically connected in series in this order, and the first substrate is not electrically connected directly to the control substrate, so that the space occupied by the wiring connecting the substrates within the inkjet recording device can be reduced compared to when the first substrate is electrically connected directly to the control substrate and the second substrate is electrically connected directly to the control substrate, thereby improving the space efficiency within the inkjet recording device.

[0086] (2) In the liquid leakage detection device of the above aspect, the pair of electrode terminals is composed of an exposed conductor portion of a first wiring arranged on the first substrate and an exposed conductor portion of a second wiring arranged on the first substrate. The other pair of electrode terminals is composed of an exposed conductor portion of a third wiring arranged on the second substrate and an exposed conductor portion of a fourth wiring arranged on the second substrate. The first wiring and the second wiring are arranged in parallel, and the third wiring and the fourth wiring are arranged in parallel. The first wiring and the third wiring are electrically connected in series, and the second wiring and the fourth wiring are electrically connected in series. The third wiring is electrically connected directly to the detection circuit, and the fourth wiring is grounded. The detection circuit may detect a voltage drop in the first wiring or the third wiring, and output a signal indicating that a liquid leak has been detected when a short circuit between the pair of electrode terminals or a short circuit between the other pair of electrode terminals is detected. According to the above aspect, it is possible to detect the leakage of liquid inside the ink jet recording apparatus with a simple configuration.

[0087] (3) In the liquid leakage detection device of the above aspect, a fifth wiring is further arranged on the first substrate, and the first wiring, the second wiring, and the fifth wiring are arranged in parallel. The second wiring and the fifth wiring are electrically connected via a resistor. A sixth wiring is further arranged on the second substrate, and the third wiring, the fourth wiring, and the sixth wiring are arranged in parallel. The fifth wiring and the sixth wiring are electrically connected in series. The side of the second wiring that is not connected to the fourth wiring and the side of the fifth wiring that is not connected to the sixth wiring are electrically connected. The second wiring and the fourth wiring, and the fifth wiring and the sixth wiring, form a single current path, and the detection circuit may output a signal to notify that the current path is not conducting when the current path is not conducting. According to the above embodiment, it is possible to easily detect electrical continuity defects with the plurality of boards connected to the control board. By using the first wiring and the third wiring, which are used to detect the occurrence of liquid leakage, for detecting electrical continuity defects with the boards, it is possible to reduce the number of wirings arranged on the first board and the second board.

[0088] (4) In the liquid leakage detection device of the above aspect, the detection circuit includes a leakage signal terminal electrically connected to the third wiring, a ground terminal electrically connected to the fourth wiring, a link signal terminal electrically connected to the sixth wiring, a first pull-up resistor one end connected to a high potential side of a signal potential used by the detection circuit, and a second pull-up resistor one end connected to the high potential side of a signal potential used by the detection circuit. The ground terminal is grounded, the leakage signal terminal is connected to the other end of the first pull-up resistor, and the link signal terminal is connected to the other end of the second pull-up resistor.

[0089] (5) In the liquid leakage detection device of the above aspect, the detection circuit may have a comparator for detecting a voltage drop in the third wiring or a voltage drop in the first wiring connected to the third wiring.

[0090] (6) In the liquid leakage detection device of the above form, the detection circuit may have an A / D converter for detecting a voltage drop in the third wiring or a voltage drop in the first wiring connected to the third wiring.

[0091] (7) The liquid leakage detection device of the above form may further include a strip-shaped liquid absorption section that absorbs liquid, wherein the pair of electrodes are arranged on a first surface of the first substrate and aligned in a first direction set on the first substrate, and the other pair of electrodes are arranged on a second surface of the second substrate and aligned in a second direction set on the second substrate, and the first substrate is placed on the liquid absorption section with the first surface facing the liquid absorption section and the first direction aligned with the longitudinal direction of the liquid absorption section, so that the pair of electrode terminals are in contact with the liquid absorption section, and the second substrate is placed on the liquid absorption section with the second surface facing the liquid absorption section and the second direction aligned with the longitudinal direction of the liquid absorption section, so that the other pair of electrode terminals are in contact with the liquid absorption section. When the liquid absorbing section absorbs liquid leaked inside the inkjet recording device, one of the pair of electrode terminals of the first substrate and the other pair of electrode terminals of the second substrate overlapping the liquid absorbing section may be short-circuited. According to the above embodiment, the first ink detection section and the second ink detection section can share the liquid absorbing section. This allows for a simpler configuration of the liquid leakage detection device compared to an embodiment in which each ink detection section is provided with its own liquid absorbing section. Furthermore, the operator simply overlaps the first substrate with the liquid absorbing section so that the first direction of the first substrate is aligned with the longitudinal direction of the liquid absorbing section, and overlaps the second substrate with the liquid absorbing section so that the second direction of the second substrate is aligned with the longitudinal direction of the liquid absorbing section. This facilitates positioning of the first substrate and the second substrate.

[0092] (8) In the liquid leakage detection device of the above form, the first substrate and the second substrate may be formed in a rectangular shape, the longitudinal direction of the first substrate may be set as the first direction, the longitudinal direction of the second substrate may be set as the second direction, the pair of electrode terminals may be arranged along the first direction and at least partially overlapping with a first virtual center line, which is an imaginary straight line located in the center of the short side of the first substrate, and the other pair of electrode terminals may be arranged along the second direction and at least partially overlapping with a second virtual center line, which is an imaginary straight line located in the center of the short side of the second substrate. According to the above embodiment, the pair of electrode terminals are arranged so that they at least partially overlap with the first imaginary center line set on the first substrate, making it easy to position the first substrate relative to the band-shaped liquid absorbent portion. While the first substrate should be arranged so that the pair of electrode terminals contact the liquid absorbent portion, in an embodiment where the pair of electrode terminals are not arranged so that they at least partially overlap with the first imaginary center line set on the first substrate, a problem of the pair of electrode terminals not contacting the liquid absorbent portion may occur if the substrate is placed upside down. According to the above embodiment, the problem of the pair of electrode terminals not contacting the liquid absorbent portion can be prevented even if the substrate is placed upside down. The same applies to the second substrate.

[0093] (9) In the liquid leakage detection device of the above form, the direction intersecting the longitudinal direction of the first substrate is set as the vertical direction of the first substrate, the direction intersecting the longitudinal direction of the second substrate is set as the vertical direction of the second substrate, the pair of electrode terminals may be arranged symmetrically in the vertical direction and the left-right direction on the first surface of the first substrate, and the other pair of electrode terminals may be arranged symmetrically in the vertical direction and the left-right direction on the second surface of the second substrate. According to the above embodiment, the pair of electrode terminals and the other pair of electrode terminals can be arranged symmetrically in the vertical direction and the horizontal direction on each substrate, which makes it easy to position the electrode terminals.

[0094] (10) In the liquid leakage detection device of the above form, the first substrate and the second substrate may be formed in a rectangular shape, the direction intersecting the longitudinal direction of the first substrate may be set as the vertical direction of the first substrate, the direction intersecting the longitudinal direction of the second substrate may be set as the vertical direction of the second substrate, the pair of electrode terminals may be arranged symmetrically and asymmetrically on the first surface of the first substrate, and the other pair of electrode terminals may be arranged symmetrically and asymmetrically on the second surface of the second substrate.

[0095] (11) In the liquid leakage detection device of the above aspect, the first substrate may be provided with a mark indicating the upward direction of the first surface, and the second substrate may be provided with a mark indicating the upward direction of the second surface. According to the above aspect, a worker who arranges the first and second boards can easily distinguish between the top and bottom of each board.

[0096] (12) According to another aspect of the present disclosure, there is provided an inkjet recording device. The inkjet recording device includes a liquid circulation unit, an ejection unit, a case storage unit, a control unit, and a liquid leakage detection device. The liquid leakage detection device includes a first substrate having a pair of electrode terminals as a first ink detection unit, a second substrate having another pair of electrode terminals as a second ink detection unit, and a control substrate having a detection circuit that detects liquid leakage. The first substrate, the second substrate, and the control substrate are electrically connected in series in this order, and the first substrate is not electrically connected directly to the control substrate. The detection circuit detects liquid leakage by detecting, via the second substrate, that the potential difference between the pair of electrode terminals or the other pair of electrode terminals has fallen below a predetermined threshold. According to the above embodiment, the first substrate, the second substrate, and the control substrate are electrically connected in series in this order, and the first substrate is not electrically connected directly to the control substrate, so that the space occupied by the wiring connecting the substrates within the inkjet recording device can be reduced compared to when the first substrate is electrically connected directly to the control substrate and the second substrate is electrically connected directly to the control substrate, thereby improving the space efficiency within the inkjet recording device.

[0097] The present disclosure is not limited to the form of the inkjet recording apparatus described above, but can be realized in various forms such as an inkjet system, a multifunction peripheral equipped with an inkjet recording apparatus, and the like. [Explanation of symbols]

[0098] 10...printing device, 10h...housing, 12...front portion, 13...operation panel, 14...media discharge port, 15...paper discharge tray, 16...paper feed tray, 17...mounting port, 18...cover member, 19...case storage section, 20...liquid circulation section, 21...tube, 22...circulation pipe, 25...pump, 30...jet execution section, 31...print head, 34...carriage, 35...media transport section, 36...transport roller, 40...control section, 7 0...liquid leakage detection device, 100...first ink detection unit, 100B...first substrate, 110...wiring, 111...electrode terminal, 120...wiring, 121...electrode terminal, 130...wiring, 190...case storage unit, 200...second ink detection unit, 200B...second substrate, 210...wiring, 211...electrode terminal, 220...wiring, 221...electrode terminal, 230...wiring, 300...detection circuit, 300B...control substrate, 301...leakage signal Terminal, 302...Ground terminal, 303...Link signal terminal, 304...First pull-up resistor, 305...Second pull-up resistor, 306...Comparator, CN...Connector, C1...Capacitor, F1, F2...Cable, IC1 to IC4...Ink cartridge, It...Short circuit current, M...Medium, N...Nozzle, R0, R1...Resistor, S1 to S4...Case, Vdd1, Vdd2...Power supply, Vink_lea k...output, Vref1, Vref2...reference potential, Vlink...output, 131...electrode terminal, 400...liquid absorption section, 500B...third board, 511...electrode terminal, CH...letter, CN1, CN101, CN201, CN202...connector, DS100, DS200, DS500, NS100, NS200...surface, E1, E11, E2, E21, E4, E51...end, HO...through hole, SW...side wall section.

Claims

1. A liquid leakage detection device provided inside an ink jet recording device, a first substrate provided with a pair of electrode terminals as a first ink detection unit, a second substrate provided with another pair of electrode terminals as a second ink detection unit, and a control substrate provided with a detection circuit that detects liquid leakage; the first board, the second board, and the control board are electrically connected in series in this order; the first board is not directly electrically connected to the control board; the detection circuit detects, via the second substrate, that a potential difference between the pair of electrode terminals or the other pair of electrode terminals falls below a predefined threshold, thereby detecting that liquid has leaked. Liquid leak detection device.

2. 2. The liquid leakage detection device according to claim 1, the pair of electrode terminals are composed of an exposed conductor portion of a first wiring arranged on the first substrate and an exposed conductor portion of a second wiring arranged on the first substrate, the other pair of electrode terminals is composed of an exposed conductor portion of a third wiring arranged on the second substrate and an exposed conductor portion of a fourth wiring arranged on the second substrate, the first wiring and the second wiring are arranged in parallel, the third wiring and the fourth wiring are arranged in parallel, the first wiring and the third wiring are electrically connected in series, the second wiring and the fourth wiring are electrically connected in series, the third wiring is electrically connected directly to the detection circuit, The fourth wiring is grounded, The detection circuit a signal indicating that a liquid has leaked is output when a short circuit between the pair of electrode terminals or a short circuit between the other pair of electrode terminals is detected by detecting a voltage drop in the first wiring or the third wiring; Liquid leak detection device.

3. 3. The liquid leakage detection device according to claim 2, a fifth wiring is further arranged on the first substrate, the first wiring, the second wiring, and the fifth wiring are arranged in parallel, and the second wiring and the fifth wiring are electrically connected via a resistor; a sixth wiring is further arranged on the second substrate, and the third wiring, the fourth wiring, and the sixth wiring are arranged in parallel; the fifth wiring and the sixth wiring are electrically connected in series, a side of the second wiring that is not connected to the fourth wiring and a side of the fifth wiring that is not connected to the sixth wiring are electrically connected to each other; the second wiring and the fourth wiring, and the fifth wiring and the sixth wiring form one current path; The detection circuit outputs a signal indicating that the current path is not conducting when the current path is not conducting. Liquid leak detection device.

4. 4. The liquid leakage detection device according to claim 3, The detection circuit a leakage signal terminal electrically connected to the third wiring; a ground terminal electrically connected to the fourth wiring; a link signal terminal electrically connected to the sixth wiring; a first pull-up resistor connected to a high potential side of a signal potential used by the detection circuit; a second pull-up resistor having one end connected to the high potential side of the signal potential used by the detection circuit; Equipped with The ground terminal is grounded, the leakage signal terminal is connected to the other terminal of the first pull-up resistor; the link signal terminal is connected to the other of the second pull-up resistors; Liquid leak detection device.

5. 5. The liquid leakage detection device according to claim 4, The detection circuit a comparator for detecting a voltage drop in the third wiring or a voltage drop in the first wiring connected to the third wiring; Liquid leak detection device.

6. 5. The liquid leakage detection device according to claim 4, The detection circuit an A / D converter for detecting a voltage drop in the third wiring or a voltage drop in the first wiring connected to the third wiring; Liquid leak detection device.

7. 2. The liquid leakage detection device according to claim 1, Further provided is a liquid absorbing portion formed in a strip shape that absorbs liquid, the pair of electrodes are arranged on a first surface of the first substrate, side by side in a first direction set on the first substrate; the other pair of electrodes are arranged on the second surface of the second substrate side by side in a second direction set on the second substrate, the first substrate is placed on the liquid absorbing portion with the first surface facing the liquid absorbing portion and the first direction aligned with the longitudinal direction of the liquid absorbing portion, so that the pair of electrode terminals come into contact with the liquid absorbing portion; the second substrate is placed on the liquid absorbing portion with the second surface facing the liquid absorbing portion and the second direction aligned with the longitudinal direction of the liquid absorbing portion, so that the other pair of electrode terminals contacts the liquid absorbing portion. Liquid leak detection device.

8. 8. The liquid leakage detection device according to claim 7, The first substrate and the second substrate are formed in a rectangular shape, a longitudinal direction of the first substrate is set as the first direction, the longitudinal direction of the second substrate is set as the second direction, the pair of electrode terminals are arranged along the first direction so as to at least partially overlap a first imaginary center line which is an imaginary straight line located at the center in the short-side direction of the first substrate, the other pair of electrode terminals are arranged along the second direction so as to at least partially overlap a second imaginary center line which is an imaginary straight line located at the center in the short-side direction of the second substrate; Liquid leak detection device.

9. 9. The liquid leakage detection device according to claim 8, a direction intersecting the longitudinal direction of the first substrate is set as a vertical direction of the first substrate, a direction intersecting the longitudinal direction of the second substrate is set as a vertical direction of the second substrate, the pair of electrode terminals are arranged vertically and horizontally symmetrically on the first surface of the first substrate, the other pair of electrode terminals are arranged vertically symmetrically and laterally symmetrically on the second surface of the second substrate; Liquid leak detection device.

10. 8. The liquid leakage detection device according to claim 7, The first substrate and the second substrate are formed in a rectangular shape, a direction intersecting the longitudinal direction of the first substrate is set as a vertical direction of the first substrate, a direction intersecting the longitudinal direction of the second substrate is set as a vertical direction of the second substrate, the pair of electrode terminals are arranged symmetrically on the first surface of the first substrate and asymmetrically on the top and bottom; the other pair of electrode terminals are arranged symmetrically on the second surface of the second substrate and asymmetrically on the top and bottom. Liquid leak detection device.

11. The liquid leakage detection device according to any one of claims 7 to 10, a mark indicating an upward direction of the first surface is provided on the first substrate; The second substrate is provided with a mark indicating the upward direction of the second surface. Liquid leak detection device.

12. An ink jet recording apparatus, The liquid leakage detection device includes a liquid circulation unit, a spray execution unit, a case storage unit, a control unit, and a liquid leakage detection device. The liquid leakage detection device includes: a first substrate provided with a pair of electrode terminals as a first ink detection unit, a second substrate provided with another pair of electrode terminals as a second ink detection unit, and a control substrate provided with a detection circuit that detects liquid leakage; the first board, the second board, and the control board are electrically connected in series in this order; the first board is not directly electrically connected to the control board; the detection circuit detects, via the second substrate, that a potential difference between the pair of electrode terminals or the other pair of electrode terminals falls below a predefined threshold, thereby detecting that liquid has leaked. Inkjet recording device.

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