Liquid leakage detection device and inkjet recording device

Abstract

To increase an amount of a liquid which can be absorbed and inhibit false detection under a high humidity environment.SOLUTION: A liquid leakage detector 30 includes: a first absorber layer 31 which absorbs a liquid; a second absorber layer 32 which is laminated on the first absorber layer 31 and absorbs the liquid; and a pair of terminals 33 which contacts only with the second absorber layer 32. The first absorber layer 31 and the second absorber layer 32 are laminated to increase an amount of the liquid which can be absorbed compared to a structure only with the second absorber layer 32 and increase a contact resistance value of the second absorber layer 32 compared to a structure only with the first absorber layer 31.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a liquid leakage detection device that detects liquid leakage and an inkjet recording apparatus equipped with the liquid leakage detection device. [Background technology]

[0002] An inkjet recording device includes an ink container, a pump, a sub-tank, an inkjet head, a cleaning liquid tank, a waste liquid tank, etc., which are connected by piping. In such a configuration, if liquid such as ink, cleaning liquid, waste liquid, etc. leaks into the device, it may cause contamination of the components constituting the device and recording paper, short-circuiting of electric circuits, etc. Therefore, conventionally, means for detecting liquid leakage within the device have been considered. For example, Patent Document 1 proposes a configuration in which a sensor detects ink absorbed in a sheet-like absorbent. Patent Document 2 proposes a configuration in which a change in the shape of a solid dissolved by ink is detected. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-340089 [Patent Document 2] JP 2006-231803 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, a configuration is conceivable in which a terminal is in contact with an absorbent that absorbs liquid, and when the leaked liquid is absorbed by the absorbent, a decrease in contact resistance between the terminal and the absorbent is detected to detect liquid leakage. In such a configuration, in order to suppress false detection, it is desirable that the contact resistance is large when the liquid is not absorbed by the absorbent. In order to increase the contact resistance, a material with a large volume resistance value is used, or, for the same volume resistance value, a thinner absorbent is preferable. However, in that case, the amount of liquid that can be absorbed is small, and there is a risk that the liquid will leak out around the absorbent. On the other hand, if the absorbent is made thicker to increase the amount that can be absorbed, moisture in the air is absorbed by the absorbent in a high humidity environment, causing the volume resistance value to decrease, and the contact resistance value also decreases accordingly, increasing the possibility of false detection.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In consideration of the above circumstances, an object of the present invention is to provide a liquid leakage detection device and an inkjet recording apparatus that can absorb a large amount of liquid and suppress false detection in a high humidity environment. [Means for solving the problem]

[0006] In order to solve the above problems, the liquid leakage detection device of the present invention comprises a first absorbent layer that absorbs liquid, a second absorbent layer that is stacked on the first absorbent layer and absorbs the liquid, and a pair of terminals that contact only the second absorbent layer, and is characterized in that, by stacking the first absorbent layer and the second absorbent layer, a greater amount of liquid can be absorbed than in the case of only the second absorbent layer, and the contact resistance value of the second absorbent layer is greater than in the case of only the first absorbent layer.

[0007] The first absorbent layer may be capable of absorbing a larger amount of the liquid than the second absorbent layer, and the second absorbent layer may have a higher contact resistance than the first absorbent layer.

[0008] The second absorbent layer may have a volume resistivity greater than that of the first absorbent layer.

[0009] The second absorbent layer may have a thickness less than that of the first absorbent layer.

[0010] The first absorption layer may have a cavity at a boundary with the second absorption layer, and the pair of terminals may pass through the second absorption layer at a location corresponding to the cavity.

[0011] A part or the whole of the boundary between the first absorbent layer and the second absorbent layer may not be bonded.

[0012] The liquid leakage detection device may include a substrate supporting the pair of terminals, a support member formed of a metal plate and supporting the substrate, and an insulating layer provided between the support member and the second absorption layer.

[0013] The liquid leakage detection device may include a substrate supporting the pair of terminals, and a support member made of resin and supporting the substrate.

[0014] An inkjet recording apparatus according to the present invention is characterized by comprising any one of the liquid leakage detection devices described above. Effect of the Invention

[0015] According to the present invention, it is possible to increase the amount of liquid that can be absorbed and to suppress false detection in a high humidity environment. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is an oblique view illustrating the appearance of a printer according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a front view illustrating a schematic internal configuration of a printer according to an embodiment of the present invention. [Diagram 3] FIG. 2 is a diagram illustrating an ink supply mechanism and a waste liquid recovery mechanism of a printer according to an embodiment of the present invention. [Figure 4] 1 is a perspective view of a liquid leakage detection device and a waste liquid pump according to an embodiment of the present invention; [Diagram 5] 1 is a perspective view showing a cross section of a liquid leakage detection device according to an embodiment of the present invention; [Figure 6] 1 is a cross-sectional view of a liquid leakage detection device according to an embodiment of the present invention. [Figure 7] 1 is a perspective view of a liquid leakage detection device according to an embodiment of the present invention; [Figure 8] FIG. 2 is a perspective view of a first absorption layer, a second absorption layer, and an insulating layer according to one embodiment of the present invention. [Figure 9] FIG. 2 is a perspective view of a first absorption layer, a second absorption layer, and an insulating layer according to one embodiment of the present invention. [Figure 10] 1 is a graph showing experimental results of contact resistance values. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] A printer 1 (an example of an inkjet recording device) according to an embodiment of the present invention will be described below with reference to the drawings.

[0018] First, the overall configuration of the printer 1 will be described. Fig. 1 is a perspective view showing the exterior of the printer 1. Fig. 2 is a front view showing a schematic internal configuration of the printer 1. Fig. 3 is a diagram showing a schematic ink supply mechanism 50 and a waste liquid collection mechanism 60 of the printer 1. In the following description, the front side of the paper in Fig. 2 is the front side (front side) of the image forming system 100, and the left and right directions are described based on the direction when the image forming system 100 is viewed from the front. In each figure, U, Lo, L, R, Fr, and Rr respectively indicate up, down, left, right, front, and rear.

[0019] The printer 1 has a rectangular parallelepiped housing 3 (see FIG. 2). A paper feed cassette 4 that stores individual sheets S such as plain paper and coated paper, and a paper feed roller 5 that feeds the sheets S from the paper feed cassette 4 are provided in the lower part of the housing 3. A transport unit 7 that attracts the sheets S and transports them in the Y direction is provided above the paper feed cassette 4. An image creating unit 6 that ejects ink onto the sheets S is provided above the transport unit 7. A pair of paper discharge rollers 8 that discharges the sheets S on which an image has been formed, and a paper discharge tray 9 on which the discharged sheets S are stacked are provided in the upper right part of the housing 3.

[0020] A transport path 10 is provided inside the housing 3, which extends from the paper feed cassette 4 through the gap between the transport unit 7 and the imaging unit 6 to the paper discharge tray 9. The transport path 10 is formed by plate-like members facing each other with a gap therebetween to allow the sheet S to pass through, and transport roller pairs 17 that hold and transport the sheet S are provided at multiple locations in the transport direction Y. A registration roller pair 18 is provided upstream of the imaging unit 6 in the transport direction.

[0021] The transport unit 7 includes an endless transport belt 21 provided with many ventilation holes (not shown) and wound around a plurality of rollers 22, a support plate 23 provided with many ventilation holes and whose upper surface contacts the inner surface of the transport belt 21, and a suction section 24 that sucks air through the ventilation holes of the support plate 23 to adsorb the sheet S to the transport belt 21. One of the rollers 22 is driven by a drive section (not shown) such as a motor to rotate the transport belt 21 in the counterclockwise direction, and the sheet S adsorbed to the transport belt 21 is transported in the Y direction.

[0022] The imaging unit 6 includes head units 11Y, 11Bk, 11C, and 11M (collectively referred to as head unit 11), which eject yellow, black, cyan, and magenta inks, respectively. Ink containers 20Y, 20Bk, 20C, and 20M (collectively referred to as ink containers 20) filled with yellow, black, cyan, and magenta inks, respectively, are connected to the head units 11Y, 11Bk, 11C, and 11M. The ink containers 20 are mounted in a container mounting portion 51 provided to the left of the paper feed cassette 4.

[0023] The head unit 11 includes one or more inkjet heads 12, for example, a plurality of inkjet heads 12 arranged in a staggered pattern (see FIG. 3). The inkjet head 12 includes a rectangular parallelepiped housing 12H whose longitudinal direction is the front-rear direction, and a nozzle plate 12P provided on the bottom of the housing 12H. The nozzle plate 12P includes a large number of nozzles arranged in the front-rear direction, and the ejection ports of each nozzle are provided on a nozzle surface 12N, which is the lower surface of the nozzle plate 12P. Each nozzle is provided with a piezoelectric element, and a drive circuit for driving the piezoelectric element is provided inside the housing 12H.

[0024] The printer 1 has an ink supply mechanism 50 that supplies ink to the inkjet heads 12 (see FIG. 3). In the figure, the ink supply mechanism 50 corresponding to one inkjet head 12 is shown. The ink supply mechanism 50 has an ink container 20, a filter 52 that filters the ink, a pump 53 that sucks ink from the ink container 20 through the filter 52, a sub-tank 54 that stores the ink sent from the pump 53, and a pump 55 that supplies the ink stored in the sub-tank 54 to the inkjet head 12. A cleaning liquid tank 61 that stores cleaning liquid is connected to the inkjet head 12.

[0025] The control unit 2 (see FIG. 2) includes a calculation unit and a storage unit. The calculation unit is, for example, a CPU (Central Processing Unit). The storage unit includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an EEPROM (Electrically Erasable Programmable Read Only Memory). The calculation unit performs various processes by reading and executing control programs stored in the storage unit. The control unit 2 may be realized by an integrated circuit that does not use software.

[0026] An operation panel 19 is provided on the right rear portion of the top surface of the housing 3 (see FIG. 1). The operation panel 19 includes a display panel, a touch panel superimposed on the display surface of the display panel, and a keypad adjacent to the display panel. The control unit 2 displays a screen showing the operation menu of the printer 1 on the display panel, and controls each part of the printer 1 in response to operations detected by the touch panel and the keypad.

[0027] The basic image formation operation of the printer 1 is as follows. When an image formation job is input to the printer 1 from an external computer or the like, the paper feed roller 5 feeds the sheet S from the paper feed cassette 4 to the transport path 10, and the pair of registration rollers 18, whose rotation has been stopped, corrects any skew of the sheet S. When the pair of registration rollers 18 feeds the sheet S to the transport unit 7 at a predetermined timing, the transport unit 7 attracts the sheet S to the transport belt 21 and transports it in the Y direction. When the control unit 2 supplies gradation data corresponding to each nozzle of the inkjet head 12 to the drive circuit in synchronization with the transport of the sheet S, the drive circuit supplies a drive signal corresponding to the gradation data to the piezoelectric element, causing ink droplets to be ejected from the nozzle, and an image is formed on the sheet S. The pair of paper discharge rollers 8 discharges the sheet S on which the image has been formed to the paper discharge tray 9.

[0028] [Treatment unit] The treatment unit 13 (see FIG. 2) includes a cap unit 70 that covers the nozzle surface 12N of the inkjet head 12, and a wipe unit 80 that cleans the nozzle surface 12N. The cap unit 70 includes a support plate 71 and a resin cap 72 provided on the upper surface of the support plate 71. One cap 72 is provided for each of the inkjet heads 12. The wipe unit 80 includes a support plate 81, a resin wipe blade 82 provided above the support plate 81, and a wipe mechanism (not shown) that drives the wipe blade 82. The wipe mechanism cleans the nozzle surface 12N by sliding the wipe blade 82 in the front-rear direction in contact with the nozzle surface 12N. The support plate 81 also serves as a tray that receives waste liquid generated during cleaning of the nozzle surface 12N.

[0029] The wipe unit 80 is disposed below the cap unit 70. The cap unit 70 and the wipe unit 80 are supported by a carriage 90 and can be raised and lowered relative to the carriage 90. The carriage 90 is supported by the housing 3 via a carriage slide mechanism (not shown). The carriage slide mechanism slides the carriage 90 in the left-right direction relative to the housing 3. The cap unit 70 is supported by the carriage 90 via a cap unit slide mechanism (not shown). The cap unit slide mechanism slides the cap unit 70 in the left-right direction relative to the carriage 90. The transport unit 7 is supported by the housing 3 via a lift mechanism (not shown). The lift mechanism raises and lowers the transport unit 7 relative to the housing 3.

[0030] FIG. 2 shows the state during image formation, in which the upper surface of the conveyor belt 21 is located approximately 1 mm below the nozzle surface 12N of the inkjet head 12, and the treatment unit 13 is retracted to a retracted position to the left of the conveyor unit 7.

[0031] The control unit 2 executes the following process at a predetermined timing. First, the control unit 2 lowers the transport unit 7 using the lifting mechanism, and slides the carriage 90 between the transport unit 7 and the imaging unit 6 using the carriage slide mechanism. Next, the control unit 2 slides the cap unit 70 to a retracted position using the cap unit slide mechanism, and raises the transport unit 7 using the lifting mechanism to push up the wiping unit 80. Next, the control unit 2 forcibly ejects ink with increased viscosity from the inkjet head 12 (purging process).

[0032] Next, the control unit 2 causes the wipe mechanism to slide the wiper blade 82 back and forth to clean the nozzle surface 12N. At this time, cleaning liquid is supplied to the nozzle surface 12N from the cleaning liquid tank 61 described above, and the ink remaining on the nozzle surface 12N is diluted. The wiper blade 82 scrapes off the waste liquid, which is a mixture of cleaning liquid and ink, and drops it onto the support plate 81.

[0033] Next, the control unit 2 lowers the transport unit 7 using the lifting mechanism, slides the cap unit 70 above the wipe unit 80 using the cap unit slide mechanism, and raises the transport unit 7 using the lifting mechanism to push up the cap unit 70 via the wipe unit 80. This operation covers the nozzle surface 12N with the cap 72, preventing clogging of the ejection ports.

[0034] [Waste Liquid Recovery Mechanism] The printer 1 is equipped with a waste liquid recovery mechanism 60 that recovers waste liquid generated by cleaning the nozzle surface 12N of the inkjet head 12 (see FIG. 3). A waste liquid pump 62 and a waste liquid tank 63 are connected to the treatment unit 13. The waste liquid pump 62 is provided in the rear, lower left part of the housing 3. The waste liquid tank 63 is provided in front of the waste liquid pump 62. The waste liquid pump 62 is, for example, a tube pump, and sucks up waste liquid accumulated in the support plate 81 of the wiping unit 80 and transports it to the waste liquid tank 63.

[0035] [Leak detection device] The liquid leakage detection device 30 is provided below the waste liquid pump 62 and detects liquid leakage from the waste liquid pump 62. Fig. 4 is a perspective view of the liquid leakage detection device 30 and the waste liquid pump 62. Fig. 5 is a perspective view showing a cross section of the liquid leakage detection device 30. Fig. 6 is a cross section of the liquid leakage detection device 30. Fig. 7 is a perspective view of the liquid leakage detection device 30. Figs. 8 and 9 are perspective views of the first absorption layer 31, the second absorption layer 32 and the insulating layer 36.

[0036] The liquid leakage detection device 30 comprises a first absorbent layer 31 that absorbs liquid, a second absorbent layer 32 that is laminated on the first absorbent layer 31 and absorbs liquid, and a pair of terminals 33 that contact only the second absorbent layer 32.By laminating the first absorbent layer 31 and the second absorbent layer 32, a greater amount of liquid can be absorbed than in the case of only the second absorbent layer 32, and the contact resistance value of the second absorbent layer 32 is greater than in the case of only the first absorbent layer 31.

[0037] [First absorption layer, second absorption layer] The first absorbent layer 31 is a layer formed of felt. The second absorbent layer 32 is a nonwoven fabric, but is essentially a thin felt layer. The second absorbent layer 32 is thinner than the first absorbent layer 31. The second absorbent layer 32 is laminated above the first absorbent layer 31. For example, Himeron (registered trademark) may be used as the second absorbent layer 32. The first absorbent layer 31 and the second absorbent layer 32 are formed using the same fibrous material. Therefore, the only substantial difference in the structure between the first absorbent layer 31 and the second absorbent layer 32 is the thickness, but the second absorbent layer 32 may be made of a material having a higher volume resistance than the first absorbent layer 31.

[0038] The first absorbent layer 31 is laid on the upper surface of the bottom plate of the housing 3 (see Figs. 4 to 6). The first absorbent layer 31 has a facing portion 31A facing a bottom portion 35B of the support member 35 (described later) with the second absorbent layer 32 and the insulating layer 36 interposed therebetween, and a non-facing portion 31B provided to the left of the facing portion 31A and not facing the bottom portion 35B of the support member 35 (see Figs. 4 to 9). A cavity 31C is formed at a position to the left of the center of the facing portion 31A (see Fig. 9). The cavity 31C penetrates in the vertical direction. The size of the cavity 31C is such that a pair of terminals 33 (described later) does not come into contact with the first absorbent layer 31. The end of the non-facing portion 31B may be bent upward to increase the volume of the felt (to ensure a large liquid absorbing space).

[0039] The second absorbent layer 32 is laminated on the upper surface of the facing portion 31A. The upper portion of the cavity 31C of the first absorbent layer 31 is blocked by the second absorbent layer 32. A part of the boundary between the second absorbent layer 32 and the first absorbent layer 31 is bonded using a double-sided adhesive tape, adhesive, or the like. For example, the front end and the rear end of the boundary are bonded. In the bonded area, the rise of the liquid from the first absorbent layer 31 to the second absorbent layer 32 due to capillary action is blocked, but in the non-bonded area, the rise of the liquid is not blocked. Therefore, from the viewpoint of detection accuracy, it is desirable that the area of ​​the bonded area is small.

[0040] An insulating layer 36 is laminated on the upper surface of the second absorbent layer 32. The insulating layer 36 is, for example, a PET (polyethylene terephthalate) film. The insulating layer 36 is provided with an opening 36A having a size equal to or slightly smaller than the cavity 31C of the first absorbent layer 31 at a position corresponding to the cavity 31C of the first absorbent layer 31 (see Figs. 5 to 8). The opening 36A penetrates in the vertical direction, and the upper surface of the second absorbent layer 32 is exposed at the opening 36A.

[0041] [Terminals, boards, support members] A support member 35 is provided above the insulating layer 36 (see FIGS. 4 to 7). The support member 35 includes a bottom portion 35B facing the facing portion 31A of the first absorption layer 31 with the insulating layer 36 and the second absorption layer 32 sandwiched therebetween, a first wall portion 351 provided above the right end portion of the bottom portion 35B, and a second wall portion 352 provided leftward from the front end portion of the first wall portion 351. The support member 35 is formed of a metal plate such as a steel plate. The second wall portion 352 is fixed to the housing 3. The bottom portion 35B is disposed with a predetermined gap between it and the insulating layer 36.

[0042] The length of the bottom 35B in the left-right direction is longer than that of the waste liquid pump 62. The waste liquid pump 62 is disposed closer to the first wall 351 and fixed to at least one of the bottom 35B and the first wall 351. The bottom 35B is provided with an opening 35A penetrating in the vertical direction, the opening 35A having a size equal to that of the cavity 31C, at a location corresponding to the cavity 31C of the first absorption layer 31. A substrate 34 is provided on the upper surface of the bottom 35B to the left of the waste liquid pump 62. The substrate 34 is larger than the opening 35A of the bottom 35B and covers almost the entire opening 35A.

[0043] The substrate 34 is provided with a pair of terminals 33 and a sensor 37. The pair of terminals 33 are provided at locations corresponding to an opening 35A at the bottom of the support member 35 and an opening 36A in the insulating layer 36, and penetrate the substrate 34 in the up-down direction. Upper ends of the pair of terminals 33 protrude from the upper surface of the substrate 34. Lower ends of the pair of terminals 33 protrude from the lower surface of the substrate 34 and penetrate the second absorption layer 32. The pair of terminals 33 contacts only the second absorption layer 32, and does not contact any of the support member 35, the insulating layer 36, the first absorption layer 31, or the bottom of the housing 3.

[0044] The sensor 37 is connected to the pair of terminals 33 and detects a decrease in the contact resistance between the pair of terminals 33 and the second absorbent layer 32. When no liquid is absorbed in the second absorbent layer 32, the contact resistance is higher than the threshold value, and when liquid is absorbed in the second absorbent layer 32, the contact resistance is lower than the threshold value. When waste liquid leaks from the waste liquid pump 62 or the like, the leaked waste liquid drops to the bottom of the housing 3 and is absorbed by the first absorbent layer 31, and rises by capillary action and permeates into the second absorbent layer 32. The volume resistance of the second absorbent layer 32 decreases due to the permeated waste liquid, and the contact resistance between the second absorbent layer 32 and the terminals 33 decreases below the threshold value. When the contact resistance is lowered below the threshold value, the sensor 37 outputs a detection signal indicating that a liquid leak has been detected to the control unit 2.

[0045] FIG. 10 is a graph showing the experimental results of the contact resistance value. The horizontal axis indicates temperature and humidity (relative humidity). The vertical axis indicates the contact resistance value. The temperature and humidity were changed in five steps: 22°C and 60%, 28°C and 80%, 32°C and 85%, 40°C and 90%, and 55°C and 90%. In the comparative example, the second absorption layer 32 is not provided, and a pair of terminals 33 are in contact with the first absorption layer 31. Therefore, in the comparative example, the contact resistance value between the terminal 33 and the first absorption layer 31 was measured, and in the embodiment, the contact resistance value between the terminal 33 and the second absorption layer 32 was measured.

[0046] As a result of the experiment, in the comparative example, the contact resistance value was 100 MΩ or more when the humidity was 60%, but dropped rapidly to about 15 MΩ when the humidity exceeded 80%. In contrast, in the embodiment, the contact resistance value was 100 MΩ or more even when the humidity was 80%, and was about 65 MΩ even when the humidity was 85%, which was a significant improvement compared to the comparative example.

[0047] The liquid leakage detection device 30 according to the present embodiment described above includes a first absorbent layer 31 that absorbs liquid, a second absorbent layer 32 that is laminated on the first absorbent layer 31 and absorbs liquid, and a pair of terminals 33 that contact only the second absorbent layer 32. Since the first absorbent layer 31 and the second absorbent layer 32 are laminated, the amount of liquid that can be absorbed is greater than that in the case where only the second absorbent layer 32 is provided, and the contact resistance value of the second absorbent layer 32 is greater than that in the case where only the first absorbent layer 31 is provided. With this configuration, the amount of liquid that can be absorbed can be made greater than that in the case where the first absorbent layer 31 is not provided. Furthermore, with this configuration, erroneous detection in a high humidity environment can be suppressed compared to the case where the pair of terminals 33 are in contact with the first absorbent layer 31.

[0048] Furthermore, according to the liquid leakage detection device 30 of this embodiment, the first absorbent layer 31 can absorb a larger amount of liquid than the second absorbent layer 32, and the second absorbent layer 32 has a higher contact resistance value than the first absorbent layer 31, so that the amount of liquid that can be absorbed can be made larger than when the first absorbent layer 31 is not provided. Furthermore, according to this configuration, false detection in a high humidity environment can be suppressed compared to when a pair of terminals 33 are in contact with the first absorbent layer 31.

[0049] Furthermore, according to the liquid leakage detection device 30 of this embodiment, since the volume resistance value of the second absorbent layer 32 is greater than that of the first absorbent layer 31, the contact resistance value of the second absorbent layer 32 can be made greater than that of the first absorbent layer 31.

[0050] Furthermore, according to the liquid leakage detection device 30 of this embodiment, the second absorbent layer 32 has a smaller thickness and a larger volume resistance than the first absorbent layer 31, so that the contact resistance value can be made larger than that of the first absorbent layer 31. Furthermore, the first absorbent layer 31 can absorb a larger amount of liquid than the second absorbent layer 32.

[0051] Furthermore, according to the liquid leakage detection device 30 of this embodiment, the first absorbent layer 31 has a cavity 31C at the boundary with the second absorbent layer 32, and the pair of terminals 33 penetrate the second absorbent layer 32 at locations corresponding to the cavity 31C, thereby ensuring that the terminals 33 come into contact with the second absorbent layer 32 while preventing the terminals 33 from coming into contact with the first absorbent layer 31.

[0052] Furthermore, according to the liquid leakage detection device 30 of this embodiment, a portion of the boundary between the first absorbent layer 31 and the second absorbent layer 32 is not bonded, so that the upward movement of liquid from the first absorbent layer 31 to the second absorbent layer 32 is not blocked.

[0053] Furthermore, the liquid leakage detection device 30 according to this embodiment includes a substrate 34 supporting a pair of terminals 33, a support member 35 formed of a metal plate and supporting the substrate 34, and an insulating layer 36 provided between the support member 35 and the second absorption layer 32, so that it is possible to prevent erroneous detection due to leakage current through the support member 35. Furthermore, since it is not necessary to manufacture a mold when forming the support member 35 from resin, it is possible to reduce costs in the case of small-scale production. Note that, although the insulating layer 36 is effective in this embodiment because metal is used extensively, the insulating layer 36 may not be provided when resin is used extensively.

[0054] The above embodiment may be modified as follows.

[0055] In the above embodiment, an example in which felt is used as the first absorbent layer 31 has been shown, but the first absorbent layer 31 may be made of sponge or the like.

[0056] In the above embodiment, an example has been shown in which the contact resistance value of the second absorption layer 32 is made larger than that of the first absorption layer 31 by making the thickness of the second absorption layer 32 smaller than that of the first absorption layer 31. However, a material having a larger volume resistance value than that of the first absorption layer 31 may be used for the second absorption layer 32. With this configuration as well, the contact resistance value of the second absorption layer 32 can be made larger than that of the first absorption layer 31.

[0057] In the above embodiment, an example is shown in which the cavity 31C penetrates the first absorption layer 31 in the vertical direction, but the cavity 31C only needs to be large enough to prevent at least one pair of terminals 33 from contacting the first absorption layer 31, and the cavity 31C does not need to penetrate the first absorption layer 31.

[0058] In the above embodiment, an example has been shown in which the first absorbent layer 31 has a cavity 31C at the boundary with the second absorbent layer 32, and the pair of terminals 33 penetrate the second absorbent layer 32 at a location corresponding to the cavity 31C, but the pair of terminals 33 do not have to penetrate the second absorbent layer 32. In that case, the first absorbent layer 31 does not have to have the cavity 31C.

[0059] In the above embodiment, an example is shown in which a part of the boundary between the first absorbent layer 31 and the second absorbent layer 32 is not bonded, but the entire boundary does not have to be bonded.

[0060] In the above embodiment, an example in which the first absorbent layer 31 and the second absorbent layer 32 are bonded to each other has been shown, but the first absorbent layer 31 and the second absorbent layer 32 may be joined to each other by a means other than bonding. For example, the first absorbent layer 31 and the second absorbent layer 32 may be integrated by entangling the fibers by needle punching.

[0061] In the above embodiment, an example has been shown in which the support member 35 is formed from a metal plate, but the support member 35 may be formed from a resin. In this case, the insulating layer 36 does not need to be provided. With this configuration, the insulating layer 36 can be omitted. Also, since the support member 35 can be manufactured by injection molding, costs can be reduced in the case of mass production.

[0062] In the above embodiment, an example has been shown in which the insulating layer 36 is laminated on the upper surface of the second absorption layer 32. However, the insulating layer 36 may be provided on the lower surface of the bottom portion 35B of the support member 35.

[0063] In addition to the configuration of the above embodiment, an insulating layer 36 may be provided on the lower surface of the first absorption layer 31. [Explanation of symbols]

[0064] 1. Printer (inkjet recording device) 30 Liquid leak detection device 31 First absorption layer 31C Cavity 32 Second absorption layer 33 Terminal 34 Substrate 35 Support member 36 Insulating layer

Claims

1. a first absorbent layer for absorbing liquid; a second absorbent layer laminated to the first absorbent layer and configured to absorb the liquid; a pair of terminals contacting only the second absorbent layer; Since the first absorbent layer and the second absorbent layer are laminated, the amount of the liquid that can be absorbed is larger than that in the case of only the second absorbent layer, and the contact resistance value of the second absorbent layer is larger than that in the case of only the first absorbent layer, the first absorbent layer has a cavity at the boundary with the second absorbent layer, A liquid leakage detection device, characterized in that the pair of terminals penetrate the second absorbent layer at locations corresponding to the cavities.

2. the first absorbent layer is capable of absorbing a larger amount of the liquid than the second absorbent layer; The liquid leakage detection device according to claim 1 , wherein the second absorbent layer has a contact resistance greater than that of the first absorbent layer.

3. 3. The liquid leakage detection device according to claim 1, wherein the second absorbent layer has a volume resistivity greater than that of the first absorbent layer.

4. 4. The liquid leakage detection device according to claim 1, wherein the second absorbent layer has a thickness smaller than that of the first absorbent layer.

5. 5. The liquid leakage detection device according to claim 1, wherein a part or all of a boundary between the first absorbent layer and the second absorbent layer is not bonded.

6. a substrate supporting the pair of terminals; A support member formed of a metal plate and configured to support the substrate; 6. The liquid leakage detection device according to claim 1, further comprising an insulating layer provided between the support member and the second absorbent layer.

7. a substrate supporting the pair of terminals; 6. The liquid leakage detection device according to claim 1, further comprising: a support member made of resin for supporting the substrate.

8. An inkjet recording apparatus comprising the liquid leakage detection device according to claim 1 .

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