Liquid detection method and liquid ejection device

Abstract

This liquid detection method comprises an irradiation step, an observation step, and a detection step. In the irradiation step, a discharge surface of a head that has the discharge surface, in which a plurality of discharge holes for discharging liquid are formed, is irradiated with light from a light source from a diagonal direction. In the observation step, the irradiated discharge surface is observed with an observation apparatus. In the detection step, the presence or absence of leakage of the liquid at the discharge surface is detected on the basis of the result of observation by the observation apparatus.

Description

[Technical Field]

[0001] The disclosed embodiments relate to a liquid detection method and a liquid ejection device. [Background technology]

[0002] Inkjet printers and inkjet plotters that use inkjet recording technology are well known as liquid ejection devices. These inkjet liquid ejection devices are equipped with a liquid ejection head that ejects liquid. The liquid ejection head has an ejection surface with multiple ejection holes that eject the liquid.

[0003] In addition, a technology has been proposed in which, when leakage of liquid from the ejection surface of a liquid ejection head is confirmed, the leaked liquid is removed by wiping the ejection surface with a wiping member such as a wiper (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-143071 Summary of the Invention

[0005] A liquid detection method according to one aspect of the embodiment includes an irradiation step, an observation step, and a detection step. The irradiation step involves using a light source to irradiate light from an oblique direction onto a discharge surface of a head having a plurality of discharge holes for discharging liquid. The observation step involves observing the illuminated discharge surface with an observation device. The detection step involves detecting whether or not there is leakage of liquid from the discharge surface based on the observation results from the observation device. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a plan view schematically showing the configuration of a liquid ejection device according to an embodiment. [Figure 2]FIG. 2 is a side view of the liquid ejection device shown in FIG. 1, as viewed from the negative direction of the Y axis. [Figure 3] FIG. 3 is a side view of the liquid ejection device shown in FIG. 1 as viewed from the positive direction of the X axis. [Figure 4] FIG. 4 is a perspective view schematically showing the external configuration of the head according to the embodiment. [Figure 5] FIG. 5 is a plan view of the head according to the embodiment. [Figure 6] FIG. 6 is a diagram schematically showing a flow path inside the head according to the embodiment. [Figure 7] FIG. 7 is a flowchart showing the procedure of a liquid detection process using the liquid ejection device according to the embodiment. [Figure 8] FIG. 8 is a diagram showing a specific example of the detection step according to the embodiment. [Figure 9] FIG. 9 is a diagram showing an example of experimental results showing the relationship between the irradiation angle of light irradiated onto the ejection surface and the visibility of the ejection surface. DETAILED DESCRIPTION OF THE INVENTION

[0007] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a liquid detection method and a liquid ejection device disclosed in the present application will be described with reference to the accompanying drawings. Note that the present disclosure is not limited to the following embodiments.

[0008] For ease of understanding, the drawings referred to below show an orthogonal coordinate system in which mutually orthogonal X-axis, Y-axis, and Z-axis directions are defined, with the positive Z-axis direction being the vertically upward direction.

[0009] <Configuration example of liquid ejection device> An example of the configuration of a liquid ejection device 1 according to an embodiment will be described with reference to Figs. 1 to 3. Fig. 1 is a plan view schematically showing the configuration of a liquid ejection device according to an embodiment. Fig. 2 is a side view of the liquid ejection device shown in Fig. 1 as viewed from the negative direction of the Y axis. Fig. 3 is a side view of the liquid ejection device shown in Fig. 1 as viewed from the positive direction of the X axis.

[0010] 1, a liquid ejection device 1 according to an embodiment ejects liquid onto a recording medium M using an inkjet method, thereby recording images, characters, etc. on the recording medium M. The recording medium M may be, for example, cloth or paper. The liquid ejection device 1 includes a transport unit 2, a carriage 3, and a head 4.

[0011] The transport unit 2 transports the recording medium M in the transport direction (here, the positive direction of the X axis). For example, the transport unit 2 may include a feed roller that pays out the recording medium M before printing, and a take-up roller that winds up the recording medium M after printing. The take-up roller is provided with a motor that drives the take-up roller to rotate about its axis and perform the winding operation of the recording medium M. The transport unit 2 may also have, in the transport path between the feed roller and the take-up roller, a tension roller that applies tension to the recording medium M, a transport roller that generates a transport force that intermittently feeds the recording medium M, and the like.

[0012] The carriage 3 is supported by a pair of guide rails (not shown) that extend along a scanning direction (here, the positive Y-axis direction) that intersects (orthogonal in this embodiment) with the transport direction (positive X-axis direction) of the recording medium M. The pair of guide rails are provided, for example, to extend laterally (here, the negative Y-axis direction) with respect to the transport path of the recording medium M. A position between the pair of guide rails on the side of the transport path of the recording medium M is set as a maintenance position where maintenance processing of the head 4 is performed. The carriage 3 is movable along the pair of guide rails. The head 4 located inside the carriage 3 is movable together with the carriage 3 between an ejection position where liquid is ejected onto the recording medium M and a maintenance position. In FIG. 1, the carriage 3 and head 4 positioned at the ejection position are indicated by two-dot chain lines, and the carriage 3 and head 4 positioned at the maintenance position are indicated by solid lines.

[0013] The head 4 is a so-called circulation type liquid ejection head that ejects liquid while circulating the liquid inside. The head 4 has an ejection surface 4s (see FIGS. 2 and 3) on which a plurality of ejection holes for ejecting the liquid are opened. The head 4 is supplied with liquid, for example, ink, from a circulation device (not shown). This circulation device supplies liquid to the head 4 while controlling the circulation pressure of the liquid circulating between the head 4 and the head 4. The head 4 and the circulation device are arranged inside the carriage 3. Note that a portion of the circulation device (for example, a tank, etc.) may be arranged outside the carriage 3.

[0014] The head 4 is formed, for example, in a substantially rectangular parallelepiped shape. The head 4 is positioned so that its longitudinal direction is perpendicular to the conveyance direction of the recording medium M (positive direction of the X-axis).

[0015] The liquid ejection device 1 also has a light source 5, an observation device 6, a first rail 7, a second rail 8, a first moving member 9, a second moving member 10, a first support member 11, and a second support member 12. In the following description, it is assumed that the carriage 3 and the head 4 are positioned at the maintenance position.

[0016] The light source 5 is supported by the first support member 11 and attached to the first moving member 9. The light source 5 is located to the side of the head 4 in a plan view. As shown in FIG. 2, the light source 5 irradiates light obliquely onto the ejection surface 4s of the head 4. The light source 5 irradiates light along the short-side direction (X-axis direction) of the head 4 in a plan view. The light source 5 irradiates the ejection surface 4s with light whose wavelength at which the light intensity is maximized is in the range of 460 nm to 620 nm. For example, a polaron light can be used as the light source 5.

[0017] The observation device 6 is supported by the second support member 12 and attached to the second moving member 10. As shown in FIGS. 2 and 3, the observation device 6 is located below the ejection surface 4s of the head 4. The observation device 6 can observe the ejection surface 4s irradiated with light. In this embodiment, the observation device 6 is a reflecting mirror that reflects the ejection surface 4s. The mirror image of the ejection surface 4s reflected by the observation device 6, which is a reflecting mirror (an example of a first observation result), is provided to the observer O as the observation result. This allows the observer O to detect whether or not there is leakage of liquid at the ejection surface 4s based on the observation result of the ejection surface 4s by the observation device 6, that is, the mirror image of the ejection surface 4s.

[0018] If an observer O visually checks the ejection surface 4s, the visibility of the ejection surface 4s is poor, making it difficult to determine whether the foreign matter on the ejection surface 4s is a mist-like deposit formed by a portion of the ejected liquid turning into a mist and adhering to the surface, or liquid that has leaked from the ejection surface 4s. Furthermore, if the observer O visually checks the ejection surface 4s while irradiating the ejection surface 4s with light from a direction perpendicular to the ejection surface 4s, the visibility of the ejection surface 4s is reduced due to the influence of light reflected from the ejection surface 4s, making it similarly difficult to determine whether there is foreign matter on the ejection surface 4s. Thus, it is difficult to accurately detect whether or not there is leakage of liquid from the ejection surface 4s by irradiating the ejection surface 4s from a direction perpendicular to the ejection surface 4s and by visual inspection.

[0019] In contrast, in the liquid ejection device 1 according to the embodiment, the light source 5 irradiates the ejection surface 4s from an oblique direction, and the ejection surface 4s that is irradiated with light is observed by the observation device 6, thereby improving the visibility of the ejection surface 4s. This allows the observer O to detect the presence or absence of leakage of liquid from the ejection surface 4s based on the presence or absence of a shadow of the liquid leaked from the ejection surface 4s, and therefore makes it easy to distinguish between the liquid leaked from the ejection surface 4s and the mist-like deposits that have adhered to the ejection surface 4s. Therefore, the liquid ejection device 1 according to the embodiment can accurately detect the presence or absence of leakage of liquid from the ejection surface 4s.

[0020] Furthermore, the mirror image of the ejection surface 4s reflected by the observation device 6, which is a reflecting mirror, is provided toward an observation position that does not overlap, in a plan view, with the path of light irradiated onto the ejection surface 4s and the path of light reflected from the ejection surface 4s. In this embodiment, the light source 5 irradiates light along the short direction (X-axis direction) of the head 4 in a plan view, and the mirror image of the ejection surface 4s is provided toward an observation position (the position of the observer O in FIG. 3 ) in the long direction (Y-axis direction) of the head 4 in a plan view. By providing the mirror image of the ejection surface 4s at such an observation position, the observer O at the observation position can confirm the mirror image of the ejection surface 4s without his or her view being obstructed by the light irradiated onto the ejection surface 4s and the light reflected from the ejection surface 4s.

[0021] As shown in FIG. 1, the first rail 7 and the second rail 8 are aligned in the widthwise direction (X-axis direction) of the head 4, and extend along the lengthwise direction (Y-axis direction) of the head 4.

[0022] In a plan view, the first rail 7 and the second rail 8 are located at positions sandwiching the maintenance position (i.e., the head 4 located at the maintenance position) in the short-side direction (X-axis direction) of the head 4. The first rail 7 is located on the negative X-axis side of the head 4 located at the maintenance position, and the second rail 8 is located on the positive X-axis side of the head 4 located at the maintenance position.

[0023] The first moving member 9 is located on the first rail 7 and moves along the first rail 7. The second moving member 10 is located on the second rail 8 and moves along the second rail 8. The first moving member 9 and the second moving member 10 may be moved along the first rail 7 and the second rail 8, respectively, by a driving device such as a motor. The first moving member 9 and the second moving member 10 may move independently of each other, or may move together.

[0024] The light source 5 is attached to the first moving member 9 via a first support member 11. By attaching the light source 5 to the first moving member 9, the light source 5 can be moved together with the first moving member 9 in the longitudinal direction (Y-axis direction) of the head 4 along the first rail 7. This makes it possible to freely change the position at which light is irradiated onto the ejection surface 4s of the head 4.

[0025] An observation device 6 is attached to the second moving member 10 via a second support member 12. By attaching the observation device 6 to the second moving member 10, it is possible to move the observation device 6 together with the second moving member 10 in the longitudinal direction (Y-axis direction) of the head 4 along the second rail 8. This makes it possible to freely change the position of the ejection surface 4s to be observed. The light source 5 and the observation device 6 may move in conjunction with each other.

[0026] The first support member 11 is positioned on the first moving member 9. As shown in FIG. 2, the first support member 11 rotatably supports the light source 5 via a first rotation shaft 11a. The light source 5 rotates around the first rotation shaft 11a, thereby changing the irradiation angle θ of the light irradiated onto the ejection surface 4s of the head 4. This makes it possible to freely adjust the irradiation angle θ of the light irradiated onto the ejection surface 4s of the head 4. The first support member 11 may be configured to be extendable and contractible along the vertical direction (Z-axis direction).

[0027] The second support member 12 is positioned on the second moving member 10. As shown in FIGS. 2 and 3, the second support member 12 rotatably supports the observation device 6 via a second rotation shaft 12a. When the observation device 6 rotates around the second rotation shaft 12a, the angle of the observation device 6 with respect to the discharge surface 4s of the head 4 is changed. This allows the angle of the observation device 6 with respect to the discharge surface 4s of the head 4 to be freely adjusted. The second support member 12 may be configured to be extendable and contractible along the vertical direction (Z-axis direction).

[0028] The liquid ejection device 1 also has a control unit 13. The control unit 13 is, for example, a CPU (Central Processing Unit), and controls the entire liquid ejection device 1 by reading and executing a program (not shown) stored in a storage unit (not shown).

[0029] <Head configuration example> Next, configuration examples of the head 4 will be described with reference to Figs. 4 to 6. Fig. 4 is a perspective view schematically showing the external configuration of the head 4 according to the embodiment. Fig. 5 is a plan view of the head 4 according to the embodiment. Fig. 6 is a view schematically showing the flow path inside the head 4 according to the embodiment.

[0030] As shown in Fig. 4, the head 4 has a housing including a box-shaped member 410 and a flat-plate-shaped member 420. The housing of the head 4 is provided with a first flow path RT1 for supplying liquid from an external circulation device to the inside of the head, and a second flow path RT2 for returning liquid collected inside the head to the circulation device. As shown in Fig. 4 or 5, the member 420 of the head 4 has a supply port P through which liquid is supplied to the inside of the head through the first flow path RT1. in and a discharge port P through which the liquid is discharged from inside the head through the second flow path RT2. out and

[0031] As shown in FIG. 5, the head 4 includes a supply reservoir 401 , a supply manifold 402 , a recovery manifold 403 , a recovery reservoir 404 , and an element 405 .

[0032] The supply reservoir 401 has an elongated shape extending in the longitudinal direction (Y-axis direction) of the head 4, and is connected to a supply manifold 402. The supply reservoir 401 has a flow path therein. As shown in FIG. 5 or FIG. 6, the first flow path RT1 and the supply port P in The liquid is supplied to the supply reservoir 401 through the supply manifold 402, and the liquid stored in the flow path of the supply reservoir 401 is sent to the supply manifold 402.

[0033] The supply manifold 402 has an elongated shape that extends in the short direction (X-axis direction) of the head 4 up to just before the recovery reservoir 404. The supply manifold 402 has therein a flow path that communicates with the flow path of the supply reservoir 401 and with the element 405. As shown in FIG. 5 or 6, the liquid that is sent from the supply reservoir 401 to the supply manifold 402 is sent from the supply manifold 402 to the element 405.

[0034] The collection manifold 403 has an elongated shape that extends in the short direction (X-axis direction) of the head 4 up to just before the supply reservoir 401. The collection manifold 403 has an internal flow path that communicates with the flow path of the collection reservoir 404 and with the element 405. As shown in FIG. 5 or 6, liquid that is not ejected to the outside from the element 405 (ejection hole 405h) is sent to the collection manifold 403.

[0035] The collection reservoir 404 has an elongated shape extending in the longitudinal direction (Y-axis direction) of the head 4, and is connected to the collection manifold 403. The collection reservoir 404 has a flow path inside. As shown in FIG. 5 or FIG. 6, the liquid that is sent from the collection manifold 403 to the collection reservoir 404 and stored in the flow path of the collection reservoir 404 is discharged from the outlet P out and is returned to the external circulation device via the second flow path RT2.

[0036] The element 405 has an ejection hole 405h. The element 405 sucks liquid from the supply manifold 402 by negative pressure generated in a pressure chamber (not shown), and ejects the sucked liquid from the ejection hole 405h toward the recording medium M by positive pressure generated in a pressure chamber (not shown).

[0037] <Liquid detection process using a liquid ejection device> Next, a liquid detection process using the liquid ejection device 1 according to the embodiment will be described with reference to Fig. 7. Fig. 7 is a flowchart showing the procedure for the liquid detection process using the liquid ejection device according to the embodiment. The procedure (irradiation step, observation step, and detection step) shown in Fig. 7 is executed after the head 4 moves from the ejection position to the maintenance position. Note that part or all of the procedure shown in Fig. 7 may be executed under the control of the control unit 13.

[0038] 7, the light source 5 irradiates the ejection surface 4s of the head 4 with light from an oblique direction (step S101, irradiation step). In the irradiation step, the light is irradiated along the short-side direction (X-axis direction) of the head 4 in a plan view. As a result, the path of the light irradiated onto the ejection surface 4s and the path of the light reflected from the ejection surface 4s are positioned along the short-side direction (X-axis direction) of the head 4.

[0039] Furthermore, the ejection surface 4s is irradiated with light having a wavelength of 460 nm or more and 620 nm or less at which the light intensity is at its maximum. It is known that light having a wavelength of less than 460 nm at which the light intensity is at its maximum, or light having a wavelength of greater than 620 nm at which the light intensity is at its maximum, significantly reduces the relative luminous efficacy in scotopic and photopic vision. By irradiating the ejection surface 4s with light having a wavelength of 460 nm or more and 620 nm or less at which the light intensity is at its maximum, the reduction in the relative luminous efficacy in scotopic and photopic vision is suppressed, thereby improving the visibility of the ejection surface 4s.

[0040] Furthermore, the ejection surface 4s is irradiated with light at an irradiation angle θ of 10° or more and 80° or less.

[0041] Next, the ejection surface 4s irradiated with light is observed by the observation device 6 (step S102, observation step). In the observation step, a mirror image of the ejection surface 4s reflected by the observation device 6, which is a reflecting mirror, is provided to the observer O as the observation result. In the observation step, the mirror image of the ejection surface 4s is provided toward the observation position (the position of the observer O in FIG. 3) in the longitudinal direction (Y-axis direction) of the head 4 in a plan view. This allows the observer O at the observation position to observe the mirror image of the ejection surface 4s without their view being obstructed by the light irradiated onto the ejection surface 4s or the light reflected from the ejection surface 4s.

[0042] Next, based on the observation results of the ejection surface 4s by the observation device 6, the presence or absence of leakage of liquid from the ejection surface 4s is detected (step S103, detection step). Specifically, for example, as shown in FIG. 8, the presence or absence of leakage of liquid from the ejection surface 4s is detected based on a mirror image of the ejection surface 4s. FIG. 8 is a diagram showing a specific example of the detection step according to the embodiment. FIG. 8 shows a mirror image of the ejection surface 4s reflected on the observation device 6, which is a reflecting mirror. Also, in FIG. 8, the area of ​​the ejection surface 4s that is irradiated with light is shown as region R.

[0043] The liquid L leaking from the ejection surface 4s is higher in height from the ejection surface 4s than the mist-like deposits adhering to the ejection surface 4s. Therefore, when light is irradiated obliquely onto the ejection surface 4s in a state where leakage of the liquid L from the ejection surface 4s occurs, a shadow L is generated around the liquid L leaking from the ejection surface 4s. s The shadow L of the liquid L s By checking the presence or absence of leakage of liquid on the mirror image of the ejection surface 4s reflected on the observation device 6, the observer O can accurately detect the presence or absence of leakage of liquid on the ejection surface 4s.

[0044] If the detection step detects leakage of liquid from the ejection surface 4s, a cleaning step of cleaning the ejection surface 4s may be executed. In this case, the liquid ejection device 1 may be provided with a cleaning unit for cleaning the ejection surface 4s of the head 4. The cleaning unit cleans the head 4 by, for example, wiping or purging.

[0045] The wiping process is a process of wiping the ejection surface 4s with a wiping member such as a flexible wiper, thereby removing the liquid exposed from the ejection surface 4s.

[0046] The purging process is a process in which liquid having a higher viscosity than that in the standard state and foreign matter are expelled from the ejection holes 405h by forcibly ejecting the liquid from the ejection holes 405h (see FIG. 6) of the head 4.

[0047] By cleaning the ejection surface 4s of the head 4 in this way, the liquid exposed on the ejection surface 4s can be removed.

[0048] Furthermore, if the detection step detects that there is leakage of liquid from the ejection surface 4s, a pressure adjustment step may be executed to adjust the pressure of the liquid inside the head 4. For example, in the pressure adjustment step, the pressure of the liquid inside the head 4 may be adjusted by lowering the supply pressure of the ejection pump of the circulation device that supplies the liquid to the head 4. Also, for example, in the pressure adjustment step, the pressure of the liquid inside the head 4 may be adjusted by increasing the suction pressure of the suction pump of the circulation device.

[0049] <About the light irradiation angle> Next, the results of an experiment evaluating the appropriate range of the irradiation angle θ of light irradiated onto the ejection surface 4s of the head 4 will be described with reference to Fig. 9. Fig. 9 is a diagram showing an example of the experimental results showing the relationship between the irradiation angle θ of light irradiated onto the ejection surface 4s and the visibility of the ejection surface 4s. In the experiment shown in Fig. 9, under conditions in which liquid leakage was occurring on the ejection surface 4s, light was irradiated onto the ejection surface 4s while changing the irradiation angle θ, and the visibility of the ejection surface 4s was investigated.

[0050] Among the irradiation angles θ illustrated in FIG. 9, the irradiation angle θ at which the visibility of the ejection surface 4s was good is marked with a "◯", and the irradiation angle θ at which the visibility of the ejection surface 4s was poor is marked with an "X". The irradiation angle θ at which the visibility of the ejection surface 4s was best is marked with a "◎". In the experiment illustrated in FIG. 9, the visibility of the ejection surface 4s was determined to be good when the observer O was able to confirm the shadow of the liquid leaking from the ejection surface 4s in the mirror image of the ejection surface 4s reflected by the observation device 6. In the experiment illustrated in FIG. 9, the visibility of the ejection surface 4s was determined to be best when the observer O was able to confirm the shadow of the liquid leaking from the ejection surface 4s in the mirror image of the ejection surface 4s reflected by the observation device 6 in the shortest time.

[0051] The experimental conditions used in the experiment shown in FIG. 9 are as follows: Distance between light source 5 and head 4: 300 mm Distance between the discharge surface 4s and the observation device 6: 200 mm Intensity of light irradiated onto ejection surface 4s: 3400 lumens Wavelength of light irradiated onto ejection surface 4s: 510 nm

[0052] When the irradiation angle θ was smaller than 10°, the visibility of the ejection surface 4s was not good. This is thought to be because, when the irradiation angle θ was smaller than 10°, the illuminance of the light irradiated onto the ejection surface 4s did not satisfy the value sufficient to confirm the shadow of the leaked liquid.

[0053] Furthermore, even when the irradiation angle θ was greater than 80°, the visibility of the ejection surface 4s was not good. This is thought to be because as the irradiation angle θ increased, the shadow of the leaked liquid became smaller and more difficult to see.

[0054] On the other hand, when the irradiation angle θ was 10° or more and 80° or less, the visibility of the ejection surface 4s was good. In particular, when the irradiation angle θ was 20° or more and 40° or less, the visibility of the ejection surface 4s was best. That is, from the experimental results shown in FIG. 9, it was confirmed that the visibility of the ejection surface 4s can be maintained good by irradiating the ejection surface 4s with light at an irradiation angle of 10° or more and 80° or less, more preferably at an irradiation angle of 20° or more and 40° or less.

[0055] (Variation) In the above-described embodiment, an example has been described in which light irradiation and observation are performed without moving the light source 5 and the observation device 6. The disclosed technology is not limited to this, and the light source 5 and the observation device 6 may be moved. In such a case, for example, in the irradiation step (step S101 in FIG. 7 ), the light source 5 may be moved in the longitudinal direction (Y-axis direction) of the head 4, and light may be sequentially irradiated onto multiple irradiation areas of the ejection surface 4s by the light source 5. Furthermore, for example, in the observation step (step S102 in FIG. 7 ), the observation device 6 may be moved in the longitudinal direction (Y-axis direction) of the head 4, and the ejection holes 405h (see FIG. 6 ) located in multiple irradiation areas of the ejection surface 4s may be sequentially observed by the observation device 6. In this way, by moving the light source 5 and the observation device 6 in conjunction with each other, the observer O can sequentially detect leakage of liquid from multiple ejection holes 405h.

[0056] In the above-described embodiment, an example has been described in which light is irradiated and observed for all of the ejection holes 405h of the ejection surface 4s. However, the disclosed technology is not limited to this, and light may be irradiated and observed for a portion of the ejection hole groups included in the plurality of ejection holes 405h of the ejection surface 4s. In such a case, for example, in the irradiation step (step S101 in FIG. 7), light may be irradiated to an ejection hole group including the ejection hole 405h located most upstream in the direction of liquid flow inside the head 4, among the plurality of ejection holes 405h of the ejection surface 4s. Here, the most upstream side refers to the supply side from which liquid is supplied to the head 4, and is the side with the highest pressure (or the side closest to the supply port P) in the flow path inside the head 4 (see FIG. 5 or FIG. 6). inIt can also be said that the ejection hole group irradiated with light is the side closest to the ejection hole 405h. In addition, for example, in the observation step (step S102 in FIG. 7), the ejection hole group irradiated with light may be observed by the observation device 6. In this way, the light is irradiated and observed only with respect to the ejection hole group including the ejection hole 405h located most upstream in the direction of flow of the liquid inside the head 4, thereby reducing the workload of the observer O.

[0057] Furthermore, in the above-described embodiment, an example has been described in which the detection step (step S103 in FIG. 7) is performed by the observer O. The disclosed technology is not limited to this, and the detection step may be performed under the control of the control unit 13. In this case, the liquid ejection device 1 may have an image pickup element that converts a mirror image of the ejection surface 4s reflected on the observation device 6, which is a reflecting mirror, into image data. The control unit 13 then performs image analysis processing on the image data obtained from the image pickup element, and uses the image analysis results to determine whether or not there is a shadow of liquid leaked from the ejection surface 4s, thereby being able to detect whether or not there is leakage of liquid from the ejection surface 4s.

[0058] In the above-described embodiment, an example has been described in which the observation device 6 is a reflecting mirror. The disclosed technology is not limited to this, and the observation device 6 may be an imaging device. In this case, in the observation step (step S102 in FIG. 7), a captured image of the ejection surface 4s (an example of a second observation result) captured by the observation device 6, which is an imaging device, may be provided as the observation result. The captured image of the ejection surface 4s may be provided to, for example, a display device (not shown). Then, in the detection step (step S103 in FIG. 7), the presence or absence of leakage of liquid from the ejection surface 4s may be detected based on the captured image of the ejection surface 4s.

[0059] Furthermore, although a circulation type liquid ejection head has been described as the head 4, a non-circulation type liquid ejection head may also be used. In this case, if the detection step detects that there is a liquid leak on the ejection surface 4s, a pressure adjustment step may be executed to adjust the pressure of the liquid inside the head 4. Specifically, the adjustment can be made by changing the height of the liquid level in the ink tank.

[0060] As described above, the liquid detection method according to the embodiment includes an irradiation step (e.g., step S101), an observation step (e.g., step S102), and a detection step (e.g., step S103). In the irradiation step, a light source (e.g., light source 5) is used to irradiate light from an oblique direction onto a discharge surface of a head (e.g., head 4), the discharge surface having a plurality of discharge holes (e.g., discharge holes 405h) that discharge liquid. In the observation step, the discharge surface irradiated with light is observed using an observation device (e.g., observation device 6). In the detection step, the presence or absence of leakage of liquid from the discharge surface is detected based on the observation results of the discharge surface by the observation device. As a result, the liquid detection method according to the embodiment can accurately detect the presence or absence of leakage of liquid from the discharge surface.

[0061] The observation device may also be a reflecting mirror. The observation step may provide a mirror image of the ejection surface reflected by the reflecting mirror as the observation result. The detection step may detect the presence or absence of liquid leakage at the ejection surface based on the mirror image of the ejection surface. As a result, according to the liquid detection method of the embodiment, an observer (for example, observer O) can accurately detect the presence or absence of liquid leakage at the ejection surface by checking the presence or absence of a shadow of the liquid in the mirror image of the ejection surface reflected by the reflecting mirror.

[0062] Furthermore, the observation step may provide a mirror image of the ejection surface toward an observation position that does not overlap, in plan view, with the paths of light irradiated onto the ejection surface and light reflected from the ejection surface. In this way, according to the liquid detection method of the embodiment, an observer at the observation position can confirm the mirror image of the ejection surface without their view being obstructed by the light irradiated onto the ejection surface and the light reflected from the ejection surface.

[0063] The head may also have a substantially rectangular parallelepiped shape. In the irradiating step, light may be irradiated along the shorter side direction of the head (e.g., the X-axis direction) in a plan view. In the observing step, a mirror image of the ejection surface may be provided toward an observation position in the longer side direction of the head (e.g., the Y-axis direction) in a plan view. As a result, according to the liquid detection method of the embodiment, an observer at the observation position can confirm the mirror image of the ejection surface without their view being obstructed by the light irradiated onto the ejection surface and the light reflected from the ejection surface.

[0064] The observation device may also be an imaging device. The observation step may provide an image of the ejection surface captured by the imaging device as the observation result. The detection step may detect the presence or absence of liquid leakage on the ejection surface based on the captured image of the ejection surface. As a result, according to the liquid detection method of the embodiment, an observer can accurately detect the presence or absence of liquid leakage on the ejection surface by checking the presence or absence of a shadow of the liquid in the captured image of the ejection surface captured by the imaging device.

[0065] Furthermore, in the irradiating step, the ejection surface may be irradiated with light having a wavelength in the range of 460 nm to 620 nm, inclusive, at which the light intensity is maximized. As a result, according to the liquid detection method of the embodiment, the decrease in relative luminous efficiency in scotopic and photopic vision is suppressed, thereby improving the visibility of the ejection surface.

[0066] Furthermore, in the irradiating step, the ejection surface may be irradiated with light at an irradiation angle of 10° or more and 80° or less (for example, irradiation angle θ). This makes it possible to maintain good visibility of the ejection surface according to the liquid detection method of the embodiment.

[0067] The head may also be movable between a discharge position where liquid is discharged onto a recording medium (e.g., recording medium M) and a maintenance position where maintenance processing of the head is performed. The irradiation step, observation step, and detection step may be performed after the head moves from the discharge position to the maintenance position. As a result, the liquid detection method according to the embodiment can detect whether or not there is leakage of liquid on the discharge surface before maintenance processing of the head is performed at the maintenance position.

[0068] The head may also have a substantially rectangular parallelepiped shape. The irradiating step may involve moving the light source in the longitudinal direction of the head (e.g., the Y-axis direction) while sequentially irradiating light onto a plurality of irradiation areas on the ejection surface from the light source. The observing step may involve moving an observing device in the longitudinal direction of the head (the Y-axis direction) while sequentially observing the ejection holes located in the plurality of irradiation areas on the ejection surface with the observing device. As a result, the liquid detection method according to the embodiment allows an observer to sequentially detect leakage of liquid from a plurality of ejection holes.

[0069] In addition, the irradiating step may irradiate light onto a group of ejection holes including ejection holes located furthest upstream in the direction of liquid flow inside the head among the multiple ejection holes on the ejection surface. The observing step may observe the ejection hole group irradiated with light using an observing device. As a result, the liquid detection method according to the embodiment can reduce the workload of the observer.

[0070] Furthermore, the liquid detection method according to the embodiment may further include a cleaning step of cleaning the ejection surface if the detection step detects leakage of liquid from the ejection surface. In this way, the liquid detection method according to the embodiment can remove the exposed liquid from the ejection surface.

[0071] Furthermore, the liquid detection method according to the embodiment may further include a pressure adjustment step of adjusting the pressure of the liquid inside the head if the detection step detects that there is a liquid leak on the ejection surface. In this way, the liquid detection method according to the embodiment can remove the liquid exposed on the ejection surface.

[0072] Further advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents. [Explanation of symbols]

[0073] 1 Liquid discharge device 2. Conveyor section 3 carriages 4 heads 4s discharge surface 5 light source 6. Observation equipment 7 First Rail 8 Second Rail 9 First moving member 10 Second moving member 11 First support member 11a First rotating shaft 12 second support member 12a Second rotating shaft 13 Control Unit 405h Discharge hole M Recording medium

Claims

1. an irradiation step of irradiating light from a light source obliquely onto a discharge surface of a head having a discharge surface on which a plurality of discharge holes for discharging a liquid are opened; an observation step of observing the irradiated ejection surface by an observation device; a detection step of detecting whether or not the liquid is leaking from the discharge surface based on the observation results by the observation device; Including, the observation device is a reflector, The observation step includes: providing a first observation result, which is a mirror image of the ejection surface reflected by the reflecting mirror, as the observation result; The detection step includes: detecting whether or not the liquid is leaking from the ejection surface based on the first observation result; The observation step includes: a mirror image of the ejection surface is provided toward an observation position that does not overlap a path of the light irradiated onto the ejection surface and a path of the light reflected from the ejection surface in a plan view; The head has a substantially rectangular parallelepiped shape, The irradiation step includes: The light is irradiated along a short-side direction of the head in a plan view, The observation step includes: A liquid detection method that provides a mirror image of the ejection surface toward the observation position in the longitudinal direction of the head in a plan view.

2. The irradiation step includes:

2. The liquid detection method according to claim 1, wherein the ejection surface is irradiated with the light having a wavelength in the range of 460 nm to 620 nm, inclusive, at which the light intensity is maximized.

3. The irradiation step includes: The liquid detection method according to claim 1 , wherein the light is irradiated onto the ejection surface at an irradiation angle of 10° to 80°.

4. the head is movable between a discharge position where the head discharges liquid onto a recording medium and a maintenance position where the head undergoes maintenance processing; The liquid detection method according to claim 1 , wherein the irradiating step, the observing step, and the detecting step are performed after the head has moved from the ejection position to the maintenance position.

5. The head has a substantially rectangular parallelepiped shape, The irradiation step includes: While moving the light source in the longitudinal direction of the head, the light source sequentially irradiates light onto a plurality of irradiation areas of the ejection surface; The observation step includes: The liquid detection method according to claim 1 , wherein the observation device is moved in the longitudinal direction of the head, and the ejection holes located in the plurality of irradiation regions of the ejection surface are sequentially observed by the observation device.

6. An irradiation process in which a light source is used to irradiate a discharge surface of a head having a discharge surface on which a plurality of discharge holes for discharging a liquid are opened from an oblique direction; an observation step of observing the irradiated ejection surface by an observation device; a detection step of detecting whether or not the liquid is leaking from the discharge surface based on the observation results by the observation device; Including, The irradiation step includes: irradiating a group of ejection holes, including an ejection hole located most upstream in a direction of flow of liquid inside the head, among the plurality of ejection holes on the ejection surface, with the light; The observation step includes: The liquid detection method includes observing the discharge hole group irradiated with the light by the observation device.

7. 7. The liquid detection method according to claim 1, further comprising a cleaning step of cleaning the ejection surface when the detection step detects that the liquid is leaking from the ejection surface.

8. A liquid detection method according to any one of claims 1 to 6, further comprising a pressure adjustment step of adjusting the pressure of the liquid inside the head if the detection step detects leakage of the liquid at the ejection surface.

9. a head having a discharge surface on which a plurality of discharge holes for discharging liquid are opened; a light source that irradiates the ejection surface with light from an oblique direction; an observation device located below the ejection surface and configured to observe the irradiated ejection surface; and The head has a substantially rectangular parallelepiped shape, a first rail and a second rail aligned in a lateral direction of the head and extending along a longitudinal direction of the head; a first moving member that moves along the first rail; a second moving member that moves along the second rail; and the light source is mounted on the first moving member; The liquid ejection device, wherein the observation device is attached to the second moving member.

10. The liquid ejection device according to claim 9 , wherein the observation device is a reflecting mirror.

11. The liquid ejection device according to claim 9 , wherein the observation device is an imaging device.

12. a first support member positioned on the first moving member and rotatably supporting the light source via a first rotation shaft; The liquid ejection device according to claim 9 , wherein the light source rotates around the first rotation axis to change the irradiation angle of the light irradiated onto the ejection surface.

13. a second support member located on the second moving member and rotatably supporting the observation instrument via a second rotation shaft; The liquid ejection device according to claim 12 , wherein the angle of the observation device relative to the ejection surface is changed by rotating the observation device around the second rotation axis.

14. the head is movable between a discharge position where the head discharges liquid onto a recording medium and a maintenance position where the head undergoes maintenance; 14. The liquid ejection device according to claim 9, wherein the first rail and the second rail are located at positions sandwiching the maintenance position in the short-side direction of the head in a plan view.

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