WO2023163181A1

WO2023163181A1 - Liquid detection method and liquid discharge device

Info

Publication number: WO2023163181A1
Application number: PCT/JP2023/007115
Authority: WO
Inventors: 喜裕由宇
Original assignee: 京セラ株式会社
Priority date: 2022-02-28
Filing date: 2023-02-27
Publication date: 2023-08-31

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

Liquid detection method and liquid ejection device

The disclosed embodiments relate to a liquid detection method and a liquid ejection device.

Inkjet printers and inkjet plotters using an inkjet recording method are known as liquid ejection devices. A liquid ejection head for ejecting liquid is mounted in such an inkjet type liquid ejection apparatus. The liquid ejection head has an ejection surface through which a plurality of ejection holes for ejecting liquid are opened.

Further, there has been proposed a technique of removing the leaked liquid by wiping the ejection surface with a wiping member such as a wiper when leakage of the liquid from the ejection surface of the liquid ejection head is confirmed (for example, , see Patent Document 1).

JP 2009-143071 A

A liquid detection method according to one aspect of the embodiment includes an irradiation process, an observation process, and a detection process. In the irradiation step, a light source obliquely irradiates an ejection surface of a head having an ejection surface in which a plurality of ejection holes for ejecting liquid are opened. The observation step observes the irradiated ejection surface with an observation device. In the detecting step, the presence or absence of leakage of liquid from the ejection surface is detected based on the observation result of the observation device.

FIG. 1 is a plan view schematically showing the configuration of the liquid ejection device according to the embodiment. FIG. 2 is a side view of the liquid ejection device shown in FIG. 1 as seen from the Y-axis negative direction. FIG. 3 is a side view of the liquid ejection device shown in FIG. 1 as seen from the positive direction of the X-axis. FIG. 4 is a perspective view schematically showing the external configuration of the head according to the embodiment. FIG. 5 is a plan view of the head according to the embodiment. FIG. 6 is a diagram schematically showing flow paths inside the head according to the embodiment. FIG. 7 is a flow chart showing a processing procedure of liquid detection processing using the liquid ejection device according to the embodiment. FIG. 8 is a diagram showing a specific example of the detection process according to the embodiment. FIG. 9 is a diagram showing an example of experimental results showing the relationship between the irradiation angle of light with which the ejection surface is irradiated and the visibility of the ejection surface.

Hereinafter, embodiments of the liquid detection method and the liquid ejection device disclosed in the present application will be described with reference to the accompanying drawings. It should be noted that the present disclosure is not limited by the embodiments shown below.

Each drawing referred to below shows an orthogonal coordinate system in which the X-axis direction, the Y-axis direction, and the Z-axis direction are defined to be orthogonal to each other, and the Z-axis positive direction is the vertically upward direction, in order to make the explanation easier to understand.

<Configuration Example of Liquid Ejecting Device>
A configuration example of a liquid ejection device 1 according to an embodiment will be described with reference to FIGS. 1 to 3. FIG. FIG. 1 is a plan view schematically showing the configuration of the liquid ejection device according to the embodiment. FIG. 2 is a side view of the liquid ejection device shown in FIG. 1 as seen from the Y-axis negative direction. FIG. 3 is a side view of the liquid ejection device shown in FIG. 1 as seen from the positive direction of the X-axis.

As shown in FIG. 1, the liquid ejecting apparatus 1 according to the embodiment ejects liquid onto the recording medium M by an inkjet method, thereby printing images, characters, and the like on the recording medium M. FIG. The recording medium M is, for example, cloth or paper. The liquid ejection device 1 has a transport section 2 , a carriage 3 and a head 4 .

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 delivery roller that delivers the recording medium M before printing and a take-up roller that takes up the recording medium M after printing. The take-up roller is provided with a motor that rotates the take-up roller about its axis and causes the recording medium M to be taken up. The transport unit 2 may include a tension roller that applies tension to the recording medium M and a transport roller that generates a transport force to intermittently feed the recording medium M, etc., on the transport path between the delivery roller and the take-up roller. .

The carriage 3 is mounted on a pair of guide rails (not shown) extending along a scanning direction (here, the positive direction of the Y axis) that intersects (perpendicularly in the embodiment) the conveying direction of the recording medium M (the positive direction of the X axis). Supported. Such a pair of guide rails is provided, for example, so as to extend laterally (here, in the Y-axis negative direction) with respect to the conveying path of the recording medium M. As shown in FIG. A position between a pair of guide rails on the side of the transport path of the recording medium M is 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 positioned inside the carriage 3 can move together with the carriage 3 between an ejection position for ejecting liquid 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.

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) through which a plurality of ejection holes for ejecting liquid are opened. A liquid such as ink is supplied to the head 4 from a circulation device (not shown). This circulation device supplies the liquid to the head 4 while controlling the circulation pressure of the liquid circulating between the heads 4 . The head 4 and circulation device are arranged inside the carriage 3 . A part of the circulation device (for example, a tank or the like) may be arranged outside the carriage 3 .

The head 4 is formed, for example, in a substantially rectangular parallelepiped shape. The head 4 is positioned such that its longitudinal direction is orthogonal to the transport direction of the recording medium M (X-axis positive direction).

Further, the liquid ejecting apparatus 1 includes 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 supporting member 11, and a second support member 12 . In the following description, it is assumed that the carriage 3 and head 4 are positioned at the maintenance position.

The light source 5 is mounted on the first moving member 9 while being supported by the first supporting member 11 . The light source 5 is positioned to the side of the head 4 in plan view. As shown in FIG. 2, the light source 5 irradiates the ejection surface 4s of the head 4 with light from an oblique direction. The light source 5 emits light along the lateral direction (X-axis direction) of the head 4 in plan view. The light source 5 irradiates the ejection surface 4s with light having a wavelength within the range of 460 nm or more and 620 nm or less, which maximizes the light intensity. As the light source 5, for example, a Polarion light can be used.

The observation device 6 is supported by the second support member 12 and mounted on the second moving member 10 . The observation device 6 is positioned below the ejection surface 4s of the head 4, as shown in FIGS. 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. A mirror image (an example of the first observation result) of the ejection surface 4s reflected on the observation device 6, which is a reflecting mirror, is provided to the observer O as the observation result. Accordingly, the observer O can detect the presence or absence of liquid leakage from the ejection surface 4s based on the result of observation of the ejection surface 4s by the observation device 6, that is, the mirror image of the ejection surface 4s.

If an observer O visually checks the ejection surface 4s, the visibility of the ejection surface 4s is poor, and the foreign matter on the ejection surface 4s is a mist-like deposit made by part of the ejected liquid becoming a mist. It is difficult to determine whether there is liquid or liquid leaked from the ejection surface 4s. Further, when the observer O visually confirms 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 deteriorated due to the influence of the reflected light from the ejection surface 4s. , it is also difficult to discriminate foreign matter on the ejection surface 4s. Thus, it is difficult to accurately detect the presence or absence of liquid leakage from the ejection surface 4s by irradiation from a direction perpendicular to the ejection surface 4s and visual observation.

In contrast, in the liquid ejection apparatus 1 according to the embodiment, the light source 5 irradiates the ejection surface 4 s with light from an oblique direction, and the observation device 6 observes the ejection surface 4 s irradiated with the light. Visibility of the ejection surface 4s can be improved. Accordingly, the observer O can detect the presence or absence of leakage of liquid from the ejection surface 4s according to the presence or absence of the shadow of the liquid that has leaked from the ejection surface 4s. It can be easily distinguished from the mist-like deposits adhering to the surface 4s. Therefore, according to the liquid ejecting apparatus 1 according to the embodiment, it is possible to accurately detect whether or not the liquid leaks from the ejection surface 4s.

In addition, the mirror image of the ejection surface 4s reflected on the observation device 6, which is a reflector, is an observation position that does not overlap the path of the light applied to the ejection surface 4s and the path of the reflected light from the ejection surface 4s in plan view. provided towards. In the present embodiment, the light source 5 emits light along the lateral direction (X-axis direction) of the head 4 in plan view, and the mirror image of the ejection surface 4s is the longitudinal direction (X-axis direction) of the head 4 in plan view. Y-axis direction) is provided toward the observation position (the position of the observer O in FIG. 3). By providing the observation position with the mirror image of the ejection surface 4s, the observer O at the observation position can view the ejection surface without being blocked by the light irradiated on the ejection surface 4s and the reflected light from the ejection surface 4s. A mirror image of 4s can be seen.

The first rail 7 and the second rail 8 are arranged in the lateral direction (X-axis direction) of the head 4 and extend along the longitudinal direction (Y-axis direction) of the head 4, as shown in FIG. do.

The first rail 7 and the second rail 8 are located at positions sandwiching the maintenance position (that is, the head 4 positioned at the maintenance position) in the lateral direction (X-axis direction) of the head 4 in plan view. The first rail 7 is positioned on the X-axis negative direction side of the head 4 positioned at the maintenance position, and the second rail 8 is positioned on the X-axis positive direction side of the head 4 positioned at the maintenance position.

The first moving member 9 is positioned on the first rail 7 and moves along the first rail 7 . The second moving member 10 is positioned 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 by driving devices such as motors. The first moving member 9 and the second moving member 10 may move independently or integrally.

A light source 5 is mounted on the first moving member 9 via a first supporting member 11 . By mounting the light source 5 on the first moving member 9 , the light source 5 can be moved along the first rail 7 in the longitudinal direction (Y-axis direction) of the head 4 together with the first moving member 9 . This makes it possible to freely change the position where the ejection surface 4s of the head 4 is irradiated with light.

The observation device 6 is attached to the second moving member 10 via the second supporting member 12 . By mounting the observation device 6 on the second moving member 10 , the observation device 6 can be moved along the second rail 8 in the longitudinal direction (Y-axis direction) of the head 4 together with the second moving member 10 . Thereby, the observed position of the ejection surface 4s can be freely changed. Note that the light source 5 and the observation device 6 may be moved together.

The first support member 11 is positioned on the first moving member 9 . The first supporting member 11 rotatably supports the light source 5 via a first rotating shaft 11a, as shown in FIG. By rotating the light source 5 around the first rotating shaft 11a, the irradiation angle θ of the light applied to the ejection surface 4s of the head 4 is changed. This makes it possible to freely adjust the irradiation angle θ of light with which the ejection surface 4s of the head 4 is irradiated. Note that the first support member 11 may be configured to be expandable and contractable along the vertical direction (Z-axis direction).

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. By rotating the observation device 6 around the second rotation shaft 12a, the angle of the observation device 6 with respect to the ejection surface 4s of the head 4 is changed. Thereby, the angle of the observation device 6 with respect to the ejection surface 4s of the head 4 can be freely adjusted. The second support member 12 may be configured to be expandable and contractable along the vertical direction (Z-axis direction).

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

<Head configuration example>
Next, a configuration example of the head 4 will be described with reference to FIGS. 4 to 6. FIG. 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 diagram schematically showing flow paths inside the head 4 according to the embodiment.

As shown in FIG. 4 , the head 4 has a housing including a box-shaped member 410 and a plate-shaped member 420 . The housing of the head 4 has a first flow path _RT1 for supplying liquid from an external circulation device to the inside of the head, and a second flow path for returning the liquid recovered inside the head to the circulation device. RT ₂ is installed. As shown in FIG. 4 or FIG. 5, the member 420 of the head 4 includes a supply port P _in through which the liquid is supplied to the inside of the head through the first flow path RT- ₁ , and a supply port Pin through which the liquid is supplied to the inside of the head through the second flow path RT- ₂ . and an outlet P _out through which the liquid is discharged.

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

The supply reservoir 401 has an elongated shape extending in the longitudinal direction (Y-axis direction) of the head 4 and is connected to the supply manifold 402 . Supply reservoir 401 has a channel therein. As shown in FIG. 5 or 6, the liquid is supplied to the supply reservoir 401 through the first flow path _RT1 and the supply port P _in , and stored in the flow path of the supply reservoir 401 is delivered to the supply manifold 402. .

The supply manifold 402 has an elongated shape extending to the front of the recovery reservoir 404 in the lateral direction (X-axis direction) of the head 4 . The supply manifold 402 internally has a channel communicating with the channel of the supply reservoir 401 and the element 405 . As shown in FIG. 5 or 6 , liquid delivered from supply reservoir 401 to supply manifold 402 is delivered from supply manifold 402 to element 405 .

The collection manifold 403 has an elongated shape extending in the short direction (X-axis direction) of the head 4 to the front of the supply reservoir 401 . The recovery manifold 403 internally has a channel that communicates with the channel of the recovery reservoir 404 and the element 405 . As shown in FIG. 5 or 6, the liquid that has not been discharged from the element 405 (discharge hole 405h) is sent to the recovery manifold 403. As shown in FIG.

The recovery reservoir 404 has an elongated shape extending in the longitudinal direction (Y-axis direction) of the head 4 and is connected to the recovery manifold 403 . The collection reservoir 404 has a channel therein. As shown in FIG. 5 or 6, the liquid sent from the recovery manifold 403 to the recovery reservoir 404 and stored in the channel of the recovery reservoir 404 is discharged from the outside through the outlet _Pout and the second channel _RT2 . sent back to the circulator.

The element 405 has a discharge hole 405h. The element 405 sucks the liquid from the supply manifold 402 by, for example, a negative pressure generated in a pressure chamber (not shown), and pushes the sucked liquid toward the recording medium M from the discharge hole 405h by a positive pressure generated in the pressure chamber (not shown). to dispense.

<Liquid Detection Processing Using Liquid Ejecting Apparatus>
Next, liquid detection processing using the liquid ejecting apparatus 1 according to the embodiment will be described with reference to FIG. FIG. 7 is a flow chart showing a processing procedure of liquid detection processing using the liquid ejection device according to the embodiment. The processing procedure (irradiation process, observation process, and detection process) 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 processing procedure shown in FIG. 7 may be executed under the control of the control unit 13 .

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

In addition, the ejection surface 4s is irradiated with light having a wavelength within the range of 460 nm or more and 620 nm or less at which the light intensity becomes maximum. Light having a maximum light intensity wavelength of less than 460 nm or light having a maximum light intensity wavelength of greater than 620 nm can significantly reduce relative luminosity in scotopic vision and photopic vision. Are known. By irradiating the ejection surface 4s with light having a wavelength within the range of 460 nm or more and 620 nm or less at which the light intensity is maximum, a decrease in relative luminosity in scotopic vision and photopic vision is suppressed. Therefore, the visibility of the ejection surface 4s is improved.

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

Subsequently, the observation device 6 observes the ejection surface 4s irradiated with light (step S102, observation step). In the observation process, the observer O is provided with a mirror image of the ejection surface 4s reflected on the observation device 6, which is a reflecting mirror, as an observation result. In the observation step, a 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 plan view. Accordingly, the observer O at the observation position can observe the mirror image of the ejection surface 4s without being obstructed by the light irradiated on the ejection surface 4s and the reflected light from the ejection surface 4s.

Subsequently, the presence or absence of liquid leakage from the ejection surface 4s is detected based on the observation result of the ejection surface 4s by the observation device 6 (step S103, detection step). Specifically, for example, as shown in FIG. 8, the presence or absence of liquid leakage from the ejection surface 4s is detected based on the mirror image of the ejection surface 4s. FIG. 8 is a diagram showing a specific example of the detection process according to the embodiment. FIG. 8 shows a mirror image of the ejection surface 4s reflected on the observing device 6, which is a reflecting mirror. Further, in FIG. 8, the region R of the ejection surface 4s that has been irradiated with light is shown.

The height of the liquid L leaked from the ejection surface 4s is greater than that of the mist-like deposits adhering to the ejection surface 4s. For this reason, under a situation where the liquid L is leaking from the ejection surface 4s, if the ejection surface 4s is irradiated with light from an oblique direction, the surroundings of the liquid L leaking from the ejection surface 4s will be A shadow _Ls is generated. By checking the presence or absence of the shadow _Ls of the liquid L in 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 the liquid from the ejection surface 4s. can.

It should be noted that if the detection step detects that there is leakage of liquid from the ejection surface 4s, a cleaning step for cleaning the ejection surface 4s may be performed. In this case, the liquid ejection device 1 may include a cleaning section for cleaning the ejection surface 4 s of the head 4 . The cleaning unit cleans the head 4 by, for example, wiping processing or purging processing.

The wiping process is, for example, a process of removing exposed liquid from the ejection surface 4s by wiping the ejection surface 4s with a wiping member such as a flexible wiper.

The purging process is a process of forcibly ejecting liquid from the ejection holes 405h (see FIG. 6) of the head 4, thereby discharging liquids and foreign substances having a higher viscosity than the standard state from the ejection holes 405h. .

By cleaning the ejection surface 4s of the head 4 in this manner, the liquid exposed from the ejection surface 4s can be removed.

Further, when the detection step detects that the liquid leaks from the ejection surface 4s, a pressure adjustment step of adjusting the pressure of the liquid inside the head 4 may be performed. 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 discharge pump of the circulation device that supplies the liquid to the head 4 . Further, 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.

<About the irradiation angle of light>
Next, experimental results of evaluating the appropriate range of the irradiation angle θ of the light irradiated onto the ejection surface 4s of the head 4 will be described with reference to FIG. FIG. 9 is a diagram showing an example of 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, the ejection surface 4s was irradiated with light while changing the irradiation angle θ under the condition that liquid was leaking from the ejection surface 4s, and the visibility of the ejection surface 4s was improved. checked for good or bad.

Among the irradiation angles θ illustrated in FIG. 9 , the irradiation angles θ at which the visibility of the ejection surface 4 s was good are associated with “◯”, and the irradiation angles at which the visibility of the ejection surface 4 s was not good. "x" is associated with θ. Also, the irradiation angle θ at which the visibility of the ejection surface 4s was the best is associated with “⊚”. In the experiment shown in FIG. 9, the visibility of the ejection surface 4s is good when the observer O can confirm the shadow of the liquid leaked from the ejection surface 4s in the mirror image of the ejection surface 4s projected on the observation device 6. was determined to be In the experiment shown in FIG. 9, 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 projected on the observation device 6 in the shortest time, the ejection surface 4s Visibility was determined to be the best.

Also, 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 ejection surface 4s and observation device 6: 200 mm
Intensity of light applied to ejection surface 4s: 3400 lumens Wavelength of light applied to ejection surface 4s: 510 nm

When the irradiation angle θ was smaller than 10°, the visibility of the ejection surface 4s was not good. This is presumably because when the irradiation angle θ is smaller than 10°, the illuminance of the light irradiated onto the ejection surface 4s does not satisfy a value at which the shadow of the leaked liquid can be confirmed.

Also, even when the irradiation angle θ was greater than 80°, the visibility of the ejection surface 4s was not good. This is probably because as the irradiation angle θ increases, the shadow of the leaked liquid becomes smaller, making it difficult to confirm.

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 the best. That is, from the experimental results shown in FIG. 9, the ejection surface 4s is irradiated with light at an irradiation angle of 10° or more and 80° or less, and more preferably at an irradiation angle of 20° or more and 40° or less. It was confirmed that good visibility of the surface 4s could be maintained.

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

Further, in the above-described embodiment, an example has been described in which light irradiation and observation are performed with respect to all the ejection holes 405h of the ejection surface 4s. The technology disclosed herein is not limited to this, and light irradiation and observation may be performed with respect to a part of the ejection hole group 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), among the plurality of ejection holes 405h of the ejection surface 4s, the ejection holes including the ejection hole 405h located on the most upstream side in the liquid flow direction inside the head 4 are exposed. Light may be applied to the group. Here, the most upstream side is the supply side to which the liquid is supplied to the head 4, and the side where the pressure is the highest in the flow path (see FIG. 5 or FIG. 6) inside the head 4 (or the most supply port). It can also be said that it is the side close to _Pin ). Further, for example, in the observation step (step S102 in FIG. 7), the observation device 6 may observe the discharge hole group irradiated with light. In this way, only the ejection hole group including the ejection hole 405h located on the most upstream side in the liquid flow direction inside the head 4 is irradiated with light and observed, thereby reducing the work burden on the observer O. be able to.

Also, in the above-described embodiment, an example in which the observer O executes the detection step (step S103 in FIG. 7) has been described. The technology disclosed herein is not limited to this, and the detection process may be executed under the control of the control unit 13 . In this case, the liquid ejecting apparatus 1 may have an imaging device that converts a mirror image of the ejection surface 4s reflected on the observation device 6, which is a reflecting mirror, into image data. Then, the control unit 13 performs image analysis processing on the image data obtained from the image sensor, and determines whether or not there is a shadow of the liquid leaked from the ejection surface 4s using the image analysis result. It is possible to detect the presence or absence of liquid leakage in the

Also, in the above-described embodiment, an example in which the observation device 6 is a reflecting mirror has been described. 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 (an example of a second observation result) of the ejection surface 4s captured by the observation device 6, which is an imaging device, may be provided as the observation result. A 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), 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.

Also, although a circulation type liquid ejection head is used as the head 4 in the description, a non-circulation type liquid ejection head may be used. In this case, when the detecting step detects that the liquid leaks from the ejection surface 4s, a pressure adjusting step of adjusting the pressure of the liquid inside the head 4 may be performed. Specifically, it can be adjusted by changing the height of the liquid surface of the ink tank.

As described above, the liquid detection method according to the embodiment includes an irradiation process (eg, step S101), an observation process (eg, step S102), and a detection process (eg, step S103). In the irradiation step, a light source (for example, A light source 5) emits light from an oblique direction. In the observation step, an observation device (for example, observation device 6) observes the ejection surface irradiated with light. In the detecting step, the presence or absence of leakage of liquid from the ejection surface is detected based on the result of observation of the ejection surface by an observation device. Thus, according to the liquid detection method according to the embodiment, it is possible to accurately detect the presence or absence of liquid leakage from the ejection surface.

Also, the observation equipment may be a reflector. The observation step may provide a mirror image of the ejection surface reflected on the reflecting mirror as an observation result. The detection step may detect the presence or absence of liquid leakage from the ejection surface based on the mirror image of the ejection surface. As a result, according to the liquid detection method according to the embodiment, an observer (for example, an observer O) confirms whether or not there is a shadow of the liquid in the mirror image of the ejection surface reflected by the reflecting mirror. The presence or absence of liquid leakage can be detected with high accuracy.

In addition, the observation step may provide a mirror image of the ejection surface toward an observation position that does not overlap the path of the light applied to the ejection surface and the path of the reflected light from the ejection surface in plan view. Thus, according to the liquid detection method according to the embodiment, the observer at the observation position can confirm the mirror image of the ejection surface without being blocked by the light irradiated on the ejection surface and the reflected light from the ejection surface. be able to.

Also, the head may have a substantially rectangular parallelepiped shape. In the irradiation step, the light may be irradiated along the short direction of the head (for example, the X-axis direction) in plan view. The observation step may provide a mirror image of the ejection surface toward an observation position in the longitudinal direction of the head (eg, Y-axis direction) in plan view. Thus, according to the liquid detection method according to the embodiment, the observer at the observation position can confirm the mirror image of the ejection surface without being blocked by the light irradiated on the ejection surface and the reflected light from the ejection surface. be able to.

Also, the observation equipment may be an imaging device. In the observation step, an image of the ejection surface captured by the imaging device may be provided as an observation result. In the detection step, presence or absence of leakage of liquid from the ejection surface may be detected based on a captured image of the ejection surface. As a result, according to the liquid detection method according to the embodiment, the observer can check whether or not there is a shadow of the liquid in the captured image of the ejection surface captured by the imaging device, thereby detecting whether or not the liquid leaks from the ejection surface. can be detected with high accuracy.

Further, in the irradiation step, the ejection surface may be irradiated with light having a wavelength within a range of 460 nm or more and 620 nm or less at which the light intensity is maximum. As a result, according to the liquid detection method according to the embodiment, the visibility of the ejection surface is improved because the decrease in relative luminosity in scotopic vision and photopic vision is suppressed.

In the irradiation step, the ejection surface may be irradiated with light at an irradiation angle (for example, irradiation angle θ) of 10° or more and 80° or less. Thus, according to the liquid detection method according to the embodiment, it is possible to maintain good visibility of the ejection surface.

Further, the head may be movable between an ejection position at which liquid is ejected onto a recording medium (for example, the recording medium M) and a maintenance position at which maintenance processing of the head is performed. The irradiation process, the observation process, and the detection process may be performed after the head moves from the ejection position to the maintenance position. Thus, according to the liquid detection method according to the embodiment, it is possible to detect the presence or absence of liquid leakage on the ejection surface before the head maintenance process is performed at the maintenance position.

Also, the head may have a substantially rectangular parallelepiped shape. In the irradiation step, the light source may sequentially irradiate a plurality of irradiation areas of the ejection surface with light while moving the light source in the longitudinal direction of the head (for example, the Y-axis direction). In the observation step, the observation device may be moved in the longitudinal direction (Y-axis direction) of the head, and the observation device may sequentially observe the ejection holes positioned in the plurality of irradiation areas of the ejection surface. Thus, according to the liquid detection method according to the embodiment, the observer can sequentially detect the leakage of the liquid from the plurality of ejection holes.

Further, in the irradiation step, light may be applied to an ejection hole group including an ejection hole located on the most upstream side in the flow direction of the liquid inside the head, among the plurality of ejection holes on the ejection surface. In the observation step, the discharge hole group irradiated with light may be observed by an observation device. Thus, according to the liquid detection method according to the embodiment, it is possible to reduce the workload of the observer.

Further, the liquid detection method according to the embodiment may further include a cleaning step of cleaning the ejection surface when the detection step detects that liquid has leaked from the ejection surface. Thus, according to the liquid detection method according to the embodiment, the liquid exposed from the ejection surface can be removed.

Further, 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 when the detection step detects that the liquid has leaked from the ejection surface. Thus, according to the liquid detection method according to the embodiment, the liquid exposed from the ejection surface can be removed.

Further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspects of the invention are not limited to the specific details and representative embodiments shown and described above. Accordingly, various changes may be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and equivalents thereof.

Reference Signs List 1 liquid ejection device 2 transportation unit 3 carriage 4 head 4s ejection surface 5 light source 6 observation device 7 first rail 8 second rail 9 first moving member 10 second moving member 11 first supporting member 11a first rotating shaft 12 2 Support member 12a Second rotating shaft 13 Control unit 405h Discharge hole M Recording medium

Claims

an irradiation step of irradiating light obliquely from a light source onto the ejection surface of a head having an ejection surface in which a plurality of ejection holes for ejecting liquid are opened;
an observation step of observing the irradiated ejection surface with an observation device;
and a detection step of detecting the presence or absence of leakage of the liquid from the ejection surface based on observation results obtained by the observation device.
The observation device is a reflector,
The observation step includes
providing, as the observation result, a first observation result that is a mirror image of the ejection surface reflected on the reflecting mirror;
The detection step includes
2. The liquid detection method according to claim 1, wherein presence or absence of leakage of said liquid from said ejection surface is detected based on said first observation result.
The observation step includes
3. The liquid according to claim 2, which provides a mirror image of the ejection surface toward an observation position that does not overlap the path of the light applied to the ejection surface and the path of the reflected light from the ejection surface in plan view. Detection method.
The head has a substantially rectangular parallelepiped shape,
The irradiation step includes
irradiating the light along the lateral direction of the head in plan view;
The observation step includes
4. The method of detecting liquid according to claim 3, wherein in plan view, a mirror image of the ejection surface is provided toward the observation position in the longitudinal direction of the head.
The observation equipment is an imaging device,
The observation step includes
providing a second observation result, which is a captured image of the ejection surface captured by the imaging device, as the observation result;
The detection step includes
2. The liquid detection method according to claim 1, wherein presence or absence of leakage of said liquid from said ejection surface is detected based on said second observation result.
The irradiation step includes
The liquid detection method according to any one of claims 1 to 5, wherein the ejection surface is irradiated with the light having a wavelength of 460 nm or more and 620 nm or less at which the light intensity becomes maximum.
The irradiation step includes
The liquid detection method according to any one of claims 1 to 6, wherein the ejection surface is irradiated with the light at an irradiation angle of 10° or more and 80° or less.
the head is movable between an ejection position for ejecting liquid onto a recording medium and a maintenance position for performing maintenance processing of the head;
8. The liquid detection method according to claim 1, wherein said irradiation step, said observation step and said detection step are executed after said head moves from said discharge position to said maintenance position.
The head has a substantially rectangular parallelepiped shape,
The irradiation step includes
sequentially irradiating light from the light source onto a plurality of irradiation areas of the ejection surface while moving the light source in the longitudinal direction of the head;
The observation step includes
9. The observation device according to claim 1, wherein the observation device sequentially observes the ejection holes positioned in the plurality of irradiation areas of the ejection surface while moving the observation device in the longitudinal direction of the head. liquid detection method.
The irradiation step includes
irradiating an ejection hole group including an ejection hole positioned most upstream in a liquid flow direction inside the head, among the plurality of ejection holes of the ejection surface, with the light;
The observation step includes
The liquid detection method according to any one of claims 1 to 8, wherein the observation device observes the ejection hole group irradiated with the light.
11. The liquid detection method according to any one of claims 1 to 10, further comprising a cleaning step of cleaning the ejection surface when the detection step detects that the liquid has leaked from the ejection surface. .
11. The method according to any one of claims 1 to 10, further comprising a pressure adjusting step of adjusting the pressure of the liquid inside the head when it is detected by the detecting step that the liquid leaks from the ejection surface. liquid detection method.
a head having an ejection surface in which a plurality of ejection holes for ejecting liquid are opened;
a light source that irradiates the ejection surface with light from an oblique direction;
an observation device positioned below the ejection surface for observing the illuminated ejection surface.
The liquid ejection device according to claim 13, wherein the observation device is a reflecting mirror.
The liquid ejection device according to claim 13, wherein the observation device is an imaging device.
The head has a substantially rectangular parallelepiped shape,
a first rail and a second rail arranged in the lateral direction of the head and extending along the 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;
the light source is mounted on the first moving member;
16. The liquid ejecting apparatus according to any one of claims 13 to 15, wherein said observation device is mounted on said second moving member.
further comprising a first support member positioned on the first moving member and rotatably supporting the light source via a first rotation shaft;
17. The liquid ejecting apparatus according to claim 16, wherein an irradiation angle of the light with which the ejection surface is irradiated is changed by rotating the light source around the first rotation axis.
further comprising a second support member positioned on the second moving member and rotatably supporting the observation device via a second rotation shaft;
18. The liquid ejection device according to claim 17, wherein an angle of said observation device with respect to said ejection surface is changed by rotating said observation device around said second rotation axis.
The head is movable between an ejection position at which liquid is ejected onto a recording medium and a maintenance position at which maintenance of the head is performed,
19. The liquid ejecting apparatus according to claim 16, wherein said first rail and said second rail are located at positions sandwiching said maintenance position in a lateral direction of said head in plan view.