JP4655617B2 - Mounting structure of liquid detection device and liquid container - Google Patents

Description

  The present invention relates to a liquid detection device and a liquid container including the same, and more particularly, to a liquid detection device mounting structure and a liquid container suitable for detecting a remaining amount of liquid in a liquid ejection device.

  A typical example of a conventional liquid ejecting apparatus is an ink jet recording apparatus provided with an ink jet recording head for image recording. As other liquid ejecting apparatuses, for example, an apparatus having a color material ejecting head used for manufacturing a color filter such as a liquid crystal display, an electrode material (conductive paste) used for forming an electrode such as an organic EL display, a surface emitting display (FED), etc. ) An apparatus equipped with an ejection head, an apparatus equipped with a bioorganic matter ejection head used for biochip production, an apparatus equipped with a sample ejection head as a precision pipette, and the like.

  In an ink jet recording apparatus which is a typical example of a liquid ejecting apparatus, an ink jet recording head having a pressure generating means for pressurizing a pressure generating chamber and a nozzle opening for ejecting the pressurized ink as ink droplets is mounted on a carriage. Has been.

  The ink jet recording apparatus is configured to be able to continue printing by continuously supplying ink in an ink container to a recording head via a flow path. The ink container is configured as a detachable cartridge that can be easily replaced by the user when the ink is consumed, for example.

  Conventionally, the ink consumption management method of the ink cartridge includes a method of managing the ink consumption by calculating the number of ink droplets ejected from the recording head and the amount of ink sucked by the maintenance by software, or an ink cartridge. There is a method of managing a point in time when a predetermined amount of ink is actually consumed by attaching an electrode for detecting a liquid level.

  However, the method of managing the ink consumption by calculating the number of ink droplet ejections and the amount of ink by software has the following problems. Some heads have variations in weight of ejected ink droplets. Although the weight variation of the ink droplets does not affect the image quality, the ink cartridge is filled with an amount of ink with a margin in consideration of the accumulation of errors in the ink consumption due to the variation. Therefore, depending on the individual, there is a problem that ink is left by the margin.

  On the other hand, the method for managing the point in time when ink is consumed by the electrode can detect the actual amount of ink, so that the remaining amount of ink can be managed with high reliability. However, since the detection of the ink level depends on the conductivity of the ink, there are disadvantages that the types of ink that can be detected are limited and the electrode sealing structure is complicated. In addition, as a material for the electrode, a noble metal having high conductivity and high corrosion resistance is usually used, which increases the manufacturing cost of the ink cartridge. Furthermore, since it is necessary to mount two electrodes, the number of manufacturing steps increases, resulting in an increase in manufacturing cost.

  An apparatus developed to solve the above problems is disclosed as a piezoelectric apparatus in Japanese Patent Application Laid-Open No. 2001-146024. This piezoelectric device can accurately detect the remaining amount of liquid and does not require a complicated seal structure, and can be used by being mounted on a liquid container.

  That is, according to the piezoelectric device described in Japanese Patent Application Laid-Open No. 2001-146024, the drive pulse forcibly oscillates when ink is present in the space facing the vibrating portion of the piezoelectric device and when ink is not present. The remaining amount of ink in the ink cartridge can be monitored by using the fact that the resonance frequency of the residual vibration signal generated due to the residual vibration (free vibration) of the vibration unit of the piezoelectric device later changes.

  FIG. 12 shows an actuator constituting the conventional piezoelectric device described above. The actuator 106 includes a substrate 178 having a circular opening 161 at the substantially center, a diaphragm 176 disposed on one surface (hereinafter referred to as “surface”) of the substrate 178 so as to cover the opening 161, and Piezoelectric layer 160 disposed on the surface side of diaphragm 176, upper electrode 164 and lower electrode 166 sandwiching piezoelectric layer 160 from both sides, upper electrode terminal 168 electrically coupled to upper electrode 164, and lower electrode 166 And an auxiliary electrode 172 disposed between the upper electrode 164 and the upper electrode terminal 168 and electrically coupled to each other.

  The piezoelectric layer 160, the upper electrode 164, and the lower electrode 166 each have a circular portion as a main body portion. The circular portions of the piezoelectric layer 160, the upper electrode 164, and the lower electrode 166 form a piezoelectric element.

  The diaphragm 176 is formed on the surface of the substrate 178 so as to cover the opening 161. The vibration region of the diaphragm 176 that actually vibrates is determined by the opening 161. The cavity 162 is formed by the portion of the diaphragm 176 that faces the opening 161 and the opening 161 of the substrate (cavity forming member) 178. The surface of the substrate 178 opposite to the piezoelectric element (hereinafter referred to as “back surface”) faces the inside of the ink container. Thereby, the cavity 162 is configured to come into contact with the liquid (ink). Note that the diaphragm 176 is liquid-tightly attached to the substrate 178 so that the liquid does not leak to the surface side of the substrate 178 even if the liquid enters the cavity 162.

In the actuator 106 according to the conventional technique described above, the residual vibration (free vibration) of the vibration part generated after the drive pulse is applied to the piezoelectric element to forcibly vibrate the vibration part is counter electromotive force generated by the same piezoelectric element. Detected as Then, utilizing the fact that the residual vibration state of the vibration part changes before and after the liquid level in the ink container passes the installation position of the actuator 106 (strictly, the position of the cavity 162), the remaining ink amount in the ink container Can be detected.
JP 2001-146024 A

  The conventional actuator (piezoelectric device) 106 described above is mounted on the container wall of the container main body 181 of the ink cartridge 180 as shown in FIG. 13, and the cavity 162 that receives the ink to be detected is provided in the ink storage space inside the ink cartridge 180. It is comprised so that it may be exposed to.

  However, since the conventional actuator (piezoelectric device) 106 described above is configured to expose the cavity 162 in the ink storage space inside the ink cartridge 180 as described above, the ink inside the ink cartridge 180 bubbles due to vibration or the like. Then, bubbles easily enter the cavity 162 of the actuator 106. When air bubbles enter the cavity 162 and stay there, the resonance frequency of the residual vibration detected by the actuator 106 becomes faster even though the remaining amount of ink in the ink cartridge 180 is sufficient, and the liquid level becomes higher. There has been a problem in that it is erroneously determined that the amount of ink remaining has passed through the position of the actuator 106.

  In addition, since the actuator 106 is configured to expose the cavity 162 in the ink storage space inside the ink cartridge 180, the ink pressure in the ink storage space is applied to the vibration plate 176 and the piezoelectric layer 160 of the actuator 106. For example, in the on-carriage ink cartridge 180, the ink in the ink storage space vibrates vigorously due to the reciprocating movement of the carriage during the printing operation, and the pressure of the ink generated by this vibration is directly applied. In other words, there is a problem of erroneous determination due to the influence of the actuator 106.

  Furthermore, it is also considered to form a wave barrier or the like for preventing ink vibration and waves at a position facing the actuator 106, but the spatial structure around the actuator 106 becomes complicated and residual vibration detected by the actuator 106. The vibration mode is complicated so that it becomes difficult to sense and the detection sensitivity may be dulled.

  Further, if the dimension of the cavity 162 of the actuator 106 is reduced in order to accurately detect the passage timing of the liquid level, an ink meniscus is likely to be formed in the cavity 162. For this reason, even though the liquid level passes through the position of the cavity 162 due to the consumption of ink, the ink remains in the cavity 162, so that the liquid level does not pass through the position of the actuator 106 and the remaining amount of ink. There was a problem of misjudging that there was enough.

  The present invention has been made in consideration of the above-described circumstances. The detection mode is improved by simplifying the vibration mode, and the presence or absence of liquid is reliably determined by reducing the influence of vibration received from the liquid. It is an object of the present invention to provide a mounting structure for a liquid detection device and a liquid container.

In order to solve the above problems, the mounting structure of the liquid detection device according to the present invention has a first surface and a second surface facing each other, and a cavity for receiving a medium to be detected is located on the first surface side. A vibrating cavity forming base formed so as to open, and the bottom surface of the cavity is formed to be capable of vibrating;
Detection comprising: a first electrode formed on the second surface side of the vibration cavity forming base; a piezoelectric layer laminated on the first electrode; and a piezoelectric element having a second electrode laminated on the piezoelectric layer Equipment,
The detection target is mounted, and an attachment target member having an upstream space communicating with the cavity via an upstream flow path, and a downstream space communicating with the cavity via a downstream flow path,
An elastic seal member that is interposed between the detection device and the attachment target member and seals between the detection device and the attachment target member;
The attachment target member is formed with a projecting protrusion protruding from the upstream channel and the downstream channel,
In a planar view, the channel protrusion has a track shape, and the upstream channel and the downstream channel are formed inside the track shape,
The elastic sealing member has the cavity and the upstream channel and the downstream flow passage is located at other than the channel walls of the flow path space which is in communication, the track shape of the passage protrusion The gist is that a gap between the detection device and the attachment target member is sealed in the outer peripheral portion of the lens .

Further, the liquid container of the present invention, a container body having a liquid delivery port for sending the liquid stored inside to the outside,
A detection device attached to the container body for detecting the liquid inside,
The detection device has a first surface and a second surface facing each other, and a cavity for receiving a medium to be detected is formed so as to open toward the first surface, and the bottom surface of the cavity vibrates. A vibration cavity forming base formed in a possible manner;
Detection comprising: a first electrode formed on the second surface side of the vibration cavity forming base; a piezoelectric layer laminated on the first electrode; and a piezoelectric element having a second electrode laminated on the piezoelectric layer And configured with
The container body has an upstream side space communicating through the cavity and the upstream channel, and a downstream space which communicates via the cavity and the downstream flow path,
The container body is formed with a channel protrusion projecting from the upstream channel and the downstream channel,
In a planar view, the channel protrusion has a track shape, and the upstream channel and the downstream channel are formed inside the track shape,
Interposed between the detector and the container body further comprising an elastic sealing member for sealing between said detector and said container body,
The elastic sealing member, the cavity and the upstream channel and the downstream flow path are arranged at other than the flow path wall of a flow path space which is in communication, the track shape of the passage protrusion The gist is that a gap between the detection device and the container main body is sealed at the outer periphery of the container . When the subject of the invention is a liquid container, the “attachment target member” in the following description means the “container body”.

  That is, the present invention includes an attachment target member having an upstream space communicating with the cavity via an upstream flow path, and a downstream space communicating with the cavity via a downstream flow path. Since the liquid is supplied to the cavity via the upstream flow path and the liquid is discharged from the cavity via the upstream flow path, the detection device is mounted on a liquid container or the like to be detected. In this case, the liquid can be supplied to the cavity via the upstream channel without exposing the cavity of the detection device to the liquid storage space to be detected.

  In this way, by configuring the upstream flow channel and the upstream flow channel of the detection device so that the liquid flows when the liquid is consumed, even if bubbles enter the cavity, the liquid flow Bubbles are pushed out of the cavity. As a result, it is possible to prevent erroneous detection of the liquid detection device due to air bubbles remaining in the cavity, improving detection accuracy, reducing the amount of liquid remaining, and reducing industrial waste.

  In addition, since it is not necessary to expose the cavity to the liquid storage space, it is possible to prevent a meniscus from being formed in the cavity when the liquid surface passes. As a result, it is possible to prevent erroneous detection of the detection device due to liquid remaining in the cavity. Moreover, since the cavity is not a space exposed toward the liquid storage space, but a space partitioned from the storage space by a member having an upstream flow path and an upstream flow path, the change in liquid level and liquid The difference in residual vibration remaining on the bottom surface of the cavity when the bottom surface of the cavity is forcibly vibrated is increased depending on the presence or absence of the noise, so that the detection sensitivity can be increased and the detection accuracy can be increased, thereby preventing erroneous detection.

  Further, since an elastic seal member is provided between the detection device and the attachment target member and seals between the detection device and the attachment target member, the detection accuracy can be ensured and the manufacturing process is simplified. .

  That is, for example, when the attachment target member and the detection device are sealed with an adhesive or the like, the adhesive easily protrudes and protrudes into the flow path in the flow path space where the cavity and the upstream flow path and the downstream flow path communicate with each other. There is a problem that bubbles are difficult to be removed due to adhesion of the adhesive, which affects the residual vibration on the bottom surface of the cavity and adversely affects the detection accuracy. Accordingly, since the adhesive must be managed so as not to protrude into the flow path, there has been a problem that the bonding process becomes extremely complicated.

  On the other hand, in the present invention, since the gap between the detection device and the attachment target member is sealed with an elastic seal member, the above-described problem of the adhesive sticking out into the flow path is eliminated, and the bubbles are attached. This eliminates the problem of deterioration in detection accuracy and the complexity of the process caused by managing the protrusion of the adhesive.

  Moreover, since the elastic seal member is disposed at a place other than the flow path wall of the flow path space where the cavity and the upstream flow path and the downstream flow path communicate with each other, the vibration of the bottom surface of the cavity is mediated through the liquid. Therefore, it is possible to prevent the detection accuracy from being lowered due to the vibration generated in the elastic seal member affecting the residual vibration on the bottom surface of the cavity.

  That is, for example, if the elastic seal member is exposed in the flow path space between the upstream flow path or the downstream flow path and the cavity, the vibration of the bottom surface of the cavity is transmitted to the elastic seal member itself via the liquid and vibrates. On the contrary, the vibration mode may be complicated, for example, the vibration of the elastic seal member affects the vibration of the bottom surface of the cavity via the liquid. Therefore, it is possible to prevent such a situation from occurring in advance by arranging it at a place other than the flow path wall in the flow path space where the cavity and the upstream flow path and the downstream flow path communicate with each other. It is possible to prevent a decrease in the above.

Further, in the present invention, the mounting target member is formed with a channel protrusion that opens the upstream channel and the downstream channel, and the channel protrusion has a track shape in a planar view. and, the upstream passage and the downstream passage is formed inside said track shape, the elastic sealing member, the cavity and the upstream channel and the downstream flow path communicated with It is arranged at a place other than the flow path wall of the flow path space, and the track-shaped outer periphery of the flow path protrusion seals between the detection device and the attachment target member, thereby providing elasticity. Sealing can be reliably performed without exposing the sealing member to the flow path.

  In the present invention, when an annular ridge surrounding the periphery of the opening of the upstream channel and the downstream channel is formed on the surface of the channel projection facing the detection device, the channel projection When the upstream flow channel and the downstream flow channel are opened to face the cavity of the detection device so that the upstream flow channel and the upstream flow channel communicate with the cavity to form the flow channel, the annular protrusion is formed. Is closely attached to the detection device, the minute gap due to the flatness of the member of the joint portion between the cavity and the channel protrusion is extremely reduced, the sealing performance is further improved, and the contact between the elastic seal member and the liquid is almost eliminated, It is possible to reliably prevent the detection accuracy from being lowered by eliminating the vibration of the elastic seal member via the liquid.

  In the present invention, when the upstream flow channel and the downstream flow channel are formed symmetrically with respect to the center of the cavity, the upstream flow channel and the downstream flow, which are spaces through which vibrations of the cavity bottom surface propagate. The space shape of the space formed including the path is simplified, and the vibration mode of residual vibration remaining on the bottom surface of the cavity is also simplified. This makes it easy to simulate residual vibration when the cavity bottom is forcibly vibrated, reducing the difference between the design and actuality, reducing the amount of adjustment work, and improving detection accuracy. It becomes.

  In the present invention, when the upstream flow channel and the downstream flow channel are each narrowed in the flow channel area with respect to the cavity and are set to have a length so that the fluid mass of the liquid exists inside Since an appropriate flow path resistance is generated in the upstream flow path and the downstream flow path, the pressure fluctuation in the cavity caused by the vibration of the cavity bottom surface is prevented from diffusing into the upstream space and the downstream space, Appropriate residual vibration can be generated to improve and secure detection accuracy.

  In the present invention, when a biasing member that fixes the detection device to the attachment target member by biasing the detection device toward the attachment target member is provided, the detection device is applied by the biasing force of the biasing member. Is securely attached to the attachment target member, and the elastic sealing member is compressed by the urging force and is brought into close contact with the detection device and the attachment target member, so that the sealing is reliably performed. Further, the elastic seal member is compressed and hardly deformed by the urging force, and even if the vibration of the bottom surface of the cavity is transmitted to the elastic seal member itself through the liquid, the elastic seal member itself is hardly vibrated. For this reason, it is possible to effectively prevent a decrease in detection accuracy due to vibration of the elastic seal member.

  In the present invention, the attachment target member has a supply side buffer chamber that communicates with the cavity via the upstream flow path as the upstream space, and a discharge side that communicates with the cavity via the downstream flow path as the downstream space. In the case of a buffer member having a buffer chamber, the upstream flow channel and the downstream flow channel through which liquid enters and exits the cavity open to the supply buffer chamber and the discharge buffer chamber, respectively, and Therefore, even if bubbles are generated by vibration of the liquid or the like in the liquid storage space, the bubbles are temporarily trapped in the supply side buffer chamber or the discharge side buffer chamber and It becomes difficult to invade. Therefore, it is possible to prevent erroneous detection of the detection device due to air bubbles remaining in the cavity.

  In addition, the upstream flow channel and the downstream flow channel through which the liquid enters and exits the cavity do not directly open to the liquid storage space, but open to the supply side buffer chamber and the discharge side buffer chamber, respectively. Therefore, since the pressure of the liquid generated in the liquid storage space does not directly act on the cavity, it is possible to prevent erroneous detection of the detection device due to the influence of pressure due to vibration of the liquid or the like.

  In the present invention, when the supply-side buffer chamber and the discharge-side buffer chamber are formed with respect to the center of the cavity, the supply-side buffer chamber and the discharge-side buffer chamber are made symmetrical to each other. The shape of the members constituting the buffer chamber is simplified, the manufacture is facilitated, and the members can be miniaturized.

  In the present invention, when the supply-side buffer chamber and the discharge-side buffer chamber each have a capacity of at least 10 times the capacity of the cavity, the pressure fluctuation of the liquid generated in the liquid storage space in the liquid container However, the sensor characteristics of the detection device are hardly affected, and erroneous detection of the detection device due to the influence of pressure due to vibration of the liquid or the like can be prevented. Furthermore, since the pressure in the buffer chambers does not increase due to vibrations at the bottom surfaces of the cavities, excess vibrations are not generated, and the vibration mode of residual vibrations remaining on the bottom surfaces of the cavities can be simplified and detection accuracy can be improved. .

  In the present invention, the buffer member is attached to a container body having a liquid delivery port for delivering the liquid stored therein to the outside, and the supply-side buffer chamber constitutes a main part of the internal space of the container body. And the discharge-side buffer chamber communicates with the liquid delivery space that communicates the liquid stored inside the internal space of the container main body with the liquid delivery port. The liquid stored in the liquid storage chamber of the container body flows from the inlet of the supply side buffer chamber of the liquid detection device and is discharged from the outlet of the discharge side buffer chamber to the liquid delivery port of the container body. Since the total amount of the liquid sent to the liquid delivery port of the container body passes through the supply side buffer chamber, the cavity, and the discharge side buffer chamber of the detection device in advance, Consumption of the body can be surely detected.

  Hereinafter, a mounting structure of a liquid detection device according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of an ink jet recording apparatus (liquid ejecting apparatus) in which a liquid detection apparatus and an ink cartridge according to an embodiment of the present invention are used. In FIG. 1, reference numeral 1 denotes a carriage. A timing belt 3 driven by a carriage motor 2 is guided by a guide member 4 so as to reciprocate in the axial direction of the platen 5.

  An ink jet recording head 12 is mounted on the side of the carriage 1 that faces the recording paper 6, and an ink cartridge 7 that supplies ink to the recording head 12 is detachably mounted on the recording head 12.

  A cap member 31 is disposed at a home position (right side in the figure) which is a non-printing area of the recording apparatus. When the recording head mounted on the carriage 1 moves to the home position, the cap member 31 performs recording. It is configured to be pressed against the nozzle forming surface of the head to form a sealed space with the nozzle forming surface. A pump unit 10 is disposed below the cap member 31 for applying a negative pressure to the sealed space formed by the cap member 31 to perform cleaning or the like.

  A wiping means 11 having an elastic plate such as rubber is disposed in the vicinity of the print area side of the cap member 31 so as to be able to advance and retreat in the horizontal direction with respect to the movement trajectory of the recording head. When reciprocating to the cap member 31 side, the nozzle forming surface of the recording head can be wiped off as necessary.

  Next, a detection apparatus to which the present invention is applied and an ink cartridge including the same will be described.

  FIG. 2 is a cross-sectional view showing a liquid detection device 60 to which the present invention is applied. 3 is a diagram showing the detection unit 13 constituting the liquid detection device 60, and FIG. 4 is a diagram showing the buffer unit 14 and the elastic seal member 29 constituting the liquid detection device 60.

  In addition, in this example, the liquid detection apparatus 60 is comprised in the whole shown in FIG. 2 including the detection part 13 equivalent to the detection apparatus of this invention, and the buffer part 14 equivalent to the attachment object member of this invention, and this liquid A description is given of an ink cartridge 70 that is configured by attaching a detection device 60 to a container body 72 described later.

  The liquid detection device 60 includes a detection unit 13 having a cavity 43, a supply-side buffer chamber (upstream space) 15 communicating with the cavity 43 via an upstream channel 55, and the cavity 43 and a downstream channel. And a buffer portion (attachment target member) 14 having a discharge side buffer chamber (downstream side space) 16 communicating with each other through 56. On the upper surface of the buffer portion 14, a trapezoidal channel protrusion 58 is formed so that the upstream channel 55 and the downstream channel 56 open to the top surface.

  The detection unit 13 is placed on the upper surface of the buffer unit 14, and the elastic seal member 29 is a channel in a channel space in which the cavity 43 communicates with the upstream channel 55 and the downstream channel 56. It is placed outside the wall. The detection unit 13 is pressed and fixed to the upper surface of the buffer unit 14 by a hook-shaped sensor fixing member 34 and an urging member 35 formed on the upper surface of the buffer unit 14.

  The detection unit 13 is configured by stacking a vibration plate 42 on a cavity plate 41, and includes a vibration cavity forming base 40 having a first surface 40 a and a second surface 40 b facing each other, and the vibration cavity forming base 40. The piezoelectric element 17 is stacked on the second surface 40b side, and the flow path forming plate (flow path forming base) 18 is stacked on the first surface 40a side of the vibration cavity forming base 40.

  A cavity 43 having a cylindrical space shape for receiving a medium (ink) to be detected is formed in the vibration cavity forming base 40 so as to open to the first surface 40 a side. The portion 43a is formed to be able to vibrate with the diaphragm 42. In other words, the contour of the portion of the entire diaphragm 42 that actually vibrates is defined by the cavity 43. A lower electrode terminal 44 and an upper electrode terminal 45 are formed at both ends of the vibration cavity forming base 40 on the second surface 40b side.

  A lower electrode (first electrode) 46 is formed on the second surface 40 b of the vibration cavity forming base 40, and the lower electrode 46 includes a substantially circular main body 46 a and the lower electrode terminal 44 from the main body 46 a. An extending portion 46 b extending in the direction and connected to the lower electrode terminal 44. The center of the substantially circular main body 46 a of the lower electrode 46 coincides with the central axis C of the cavity 43.

  The substantially circular main body 46 a of the lower electrode 46 is formed with a larger diameter than the circular cavity 43 and covers substantially the entire region corresponding to the cavity 43. The substantially circular main body 46 a of the lower electrode 46 includes a notch 46 c formed so as to enter the inner side of the position corresponding to the peripheral edge 43 b of the cavity 43.

  A piezoelectric layer 47 is laminated on the lower electrode 46, and the piezoelectric layer 47 has a circular main body portion 47 a formed with a smaller diameter than the cavity 43 and a main body portion within a range corresponding to the cavity 43. And a protruding portion 47b protruding from 47a. As can be seen from FIG. 2, the entire piezoelectric layer 47 is within the region corresponding to the cavity 43. In other words, the piezoelectric layer 47 does not have any part extending across the position corresponding to the peripheral edge 43 b of the cavity 43.

  The center of the main body portion 47a of the piezoelectric layer 47 coincides with the central axis C of the cavity 43, and the main body portion 47a of the piezoelectric layer 47 is substantially entirely excluding the portion corresponding to the notch portion 46c of the lower electrode 46. It is laminated on the lower electrode 46.

  An auxiliary electrode 48 is formed on the second surface 40 b side of the vibration cavity forming base 40. The auxiliary electrode 48 extends from the outside of the region corresponding to the cavity 43 to the inside of the region corresponding to the cavity 43 beyond the position corresponding to the peripheral edge 43 b of the cavity 43. A part of the auxiliary electrode 48 is located inside the notch 46 c of the lower electrode (first electrode) 46, and the protruding portion 47 b of the piezoelectric layer 47 and the vicinity thereof from the second surface 40 b side of the vibration cavity forming base 40. I support it. The auxiliary electrode 48 is preferably made of the same material as the lower electrode 46 and has the same thickness. As described above, the auxiliary electrode 48 supports the protruding portion 47b of the piezoelectric layer 47 and the vicinity thereof from the second surface 40b side of the vibration cavity forming base 40, thereby preventing the piezoelectric layer 47 from having a step and providing a mechanical strength. A decrease can be prevented.

  A circular main body 49 a of an upper electrode (second electrode) 49 is laminated on the piezoelectric layer 47, and the upper electrode 49 is formed to have a smaller diameter than the main body 47 a of the piezoelectric layer 47. The upper electrode 49 has an extending portion 49 b that extends from the main body portion 49 a and is connected to the auxiliary electrode 48. As can be seen from FIG. 2, the position P at which the connection between the extended portion 49 b of the upper electrode 49 and the auxiliary electrode 48 starts is located within the region corresponding to the cavity 43.

  The piezoelectric element 17 is formed by the main body portions of the lower electrode 46, the piezoelectric layer 47, and the upper electrode 49.

  As can be seen from FIG. 3, the upper electrode 49 is electrically connected to the upper electrode terminal 45 via the auxiliary electrode 48. By connecting the upper electrode 49 to the upper electrode terminal 45 through the auxiliary electrode 48 in this way, the step caused by the total thickness of the piezoelectric layer 47 and the lower electrode 46 is reduced in both the upper electrode 49 and the auxiliary electrode 48. Can be absorbed by. For this reason, it is possible to prevent the mechanical strength from being lowered due to a large step in the upper electrode 49.

  The main body 49 a of the upper electrode 49 has a circular shape, and the center thereof coincides with the central axis C of the cavity 43. The main body 49 a of the upper electrode 49 is formed with a smaller diameter than both the main body 47 a of the piezoelectric layer 47 and the cavity 43.

  Thus, the main body portion 47 a of the piezoelectric layer 47 has a structure sandwiched between the main body portion 49 a of the upper electrode 49 and the main body portion 46 a of the lower electrode 46. Thereby, the piezoelectric layer 47 can be effectively deformed and driven.

  Of the main body 46 a of the lower electrode 46 and the main body 49 a of the upper electrode 49 that are electrically connected to the piezoelectric layer 47, the main body 49 a of the upper electrode 49 is formed to have a smaller diameter. Therefore, the main body 49a of the upper electrode 49 determines the range of the portion of the piezoelectric layer 47 that generates the piezoelectric effect.

  The centers of the main body portion 47 a of the piezoelectric layer 47, the main body portion 49 a of the upper electrode 49, and the main body portion 46 a of the lower electrode 46 coincide with the central axis C of the cavity 43. In addition, the central axis C of the cylindrical cavity 43 that determines the portion of the vibration plate 42 that can vibrate is located at the center of the entire liquid detection device 60.

  The portion of the diaphragm 42 that can be vibrated defined by the cavity 43, the portion of the main body 46 a of the lower electrode 46 that corresponds to the cavity 43, the main body 47 a and the protrusion 47 b of the piezoelectric layer 47, and the main body of the upper electrode 49. Portions corresponding to the cavity 43 of the portion 49 a and the extension portion 49 b constitute a vibrating portion 61 of the liquid detection device 60. The center of the vibration part 61 of the liquid detection device 60 is coincident with the center of the liquid detection device 60.

  Further, the main body portion 47 a of the piezoelectric layer 47, the main body portion 49 a of the upper electrode 49, the main body portion 46 a of the lower electrode 46, and the vibrating portion of the diaphragm 42 (that is, the portion corresponding to the bottom surface portion 43 a of the cavity 43) are circular. In addition, since the entire piezoelectric layer 47, that is, the main body portion 47 a and the protruding portion 47 b of the piezoelectric layer 47 are disposed inside the region corresponding to the cavity 43, the vibrating portion of the liquid detection device 60 Reference numeral 61 denotes a shape that is substantially symmetrical with respect to the center of the liquid detection device 60.

  Furthermore, the liquid detection device 60 according to the present embodiment includes a flow path forming plate (flow path forming base) 18 that is laminated and bonded to the first surface 40 a of the vibration cavity forming base 40.

  The flow path forming plate 18 includes an ink supply path (liquid supply path) 19 for supplying ink to be detected to the cavity 43, and an ink discharge path (liquid discharge path) 20 for discharging the ink to be detected from the cavity 43. Is formed. The ink supply path 19 and the ink discharge path 20 are formed in the same size and shape, and both have a cylindrical space shape.

  The ink supply path 19 and the ink discharge path 20 formed in the flow path forming plate 18 are both formed in a region corresponding to the circular cavity 43, and the ink supply path 19 and the ink discharge path 20 are They are arranged symmetrically with respect to the central axis C of the cavity 43. Thereby, the space formed including the cavity 43, the ink supply path 19 and the ink discharge path 20 is in relation to the central axis C of the cavity existing in the region sandwiched between the ink supply path 19 and the ink discharge path 20. It is formed symmetrically.

  In addition, the ink supply path 19 and the ink discharge path 20 each have a flow path area narrowed with respect to the cavity 43. That is, in this example, one ink supply path 19 and one ink discharge path 20 are formed for one cavity 43, but the flow path of one flow path (ink supply path 19 or ink discharge path 20). The area is set to be smaller than at least half of the area of the cavity 43. Further, the ink supply path 19 and the ink discharge path 20 are set to a certain length so that the fluid mass of the liquid exists inside.

  On the other hand, the liquid detection device 60 communicates with the ink supply path 19 and the supply side buffer chamber 15 where the ink supplied to the ink supply path 19 exists, and the ink discharge path 20 communicates with the ink discharge path 20. A buffer section 14 having a discharge-side buffer chamber 16 in which the ink discharged from the pipe is present.

  In this example, the buffer unit 14 has a rectangular shape that is slightly larger than the liquid detection device 60 in plan view, and is formed in a rectangular parallelepiped shape as a whole. The interior of the buffer unit 14 is divided into two spaces of the same size and shape by a single partition wall 21 disposed in the center, one being the supply side buffer chamber 15 and the other being the discharge side buffer. It is chamber 16.

  An inflow opening 22 through which ink flows into the supply-side buffer chamber 15 and an outflow opening 23 through which ink flows out from the discharge-side buffer chamber 16 are formed on the opposite side of the surface of the buffer unit 14 to which the detection unit 13 is joined. Is formed. Further, on the surface to which the detection unit 13 of the buffer unit 14 is attached, an upstream flow path 55 for supplying the ink flowing into the supply side buffer chamber 15 to the cavity 43 through the ink supply path 19, and the cavity 43 And a downstream channel for allowing the ink to flow out to the supply buffer chamber 15 via the ink discharge channel 20.

  Further, on the surface of the buffer unit 14 facing the detection unit 13, a channel projection 58 is formed so as to project the upstream channel 55 and the downstream channel 56. The flow path protrusion 58 is formed in a trapezoidal shape having a track shape in a planar view, and the upstream flow path 55 and the downstream flow path 56 are opened on the base surface (top surface). Further, on the surface of the flow path protrusion 58 that faces the detection unit 13, an annular protrusion 57 that surrounds both the upstream flow path 55 and the downstream flow path 56 is formed. The annular protrusion 57 has a track shape similar to the planar shape of the flow path protrusion 58, and an upstream flow path 55 and a downstream flow path 56 are opened inside the annular protrusion 57.

  Due to the presence of the annular ridge 57, the annular ridge 57 is pressed when the surfaces of the upstream and downstream flow paths 55 and 56 of the flow path protrusion 58 are pressed against the detection unit 13. Is slightly deformed and is in close contact with the flow path forming plate 18 of the detection unit 13, and the minute gap due to the flatness of the joint portion between the lower surface of the flow path forming plate 18 and the upper surface of the flow path protrusion 58 is extremely reduced.

  Then, in a state where the detection unit 13 is placed on the upper surface of the buffer unit 14 so that the top surface of the flow channel projection 58 and the lower surface of the detection unit 13 face each other, the elastic seal member 29 is The outer peripheral portion of the portion 58 is disposed between the detection portion 13 and the buffer portion 14 so as to seal between the detection portion 13 and the buffer portion 14.

  The elastic seal member 29 is formed in a rectangular plate shape that is set slightly larger than the detection unit 13 and slightly smaller than the buffer unit 14 as a whole. A track-shaped opening is formed in the central portion of the elastic seal member 29 so as to be fitted to the outer peripheral portion of the flow path protrusion 58. The elastic seal member 29 has a thickness larger than the height of the flow path protrusion 58 and is compressed when the detection unit 13 is pressed against the buffer unit 14 to detect the detection unit 13 and the buffer unit. 14 is sealed.

  As the material of the elastic seal member 29, an elastic member such as rubber or elastomer can be used, but particularly preferable is that a polymer is blended with oil in a three-dimensional network structure to obtain an appropriate hardness / loss characteristic / spring constant. The set elastic member for vibration isolation (Micro Network Controlled Structure) can be suitably used.

  On the other hand, sensor fixing members 34 are formed on the left and right end portions of the upper surface of the buffer portion 14 so as to extend upward and have a tip bent inwardly in a bowl shape. In the sensor fixing member 34, plate-like vertical pieces 34A extending in the vertical direction in FIG. 2 are erected on the left and right sides of the upper surface of the buffer portion 14, and the plate-like horizontal pieces are inward from the tip of the vertical piece 34A. 34B is bent and formed in a bowl shape.

  Positioning protrusions 37 for positioning the biasing member 35 are formed on the lower surface of the horizontal piece 34B of the sensor fixing member 34 and the upper surfaces of the lower electrode terminal 44 and the upper electrode terminal 45 of the detection unit 13. The urging member 35 is a substantially laterally U-shaped leaf spring, and a fitting hole (not shown) that fits the projection is formed in the vicinity of the laterally U-shaped free end.

  With such a structure, the elastic seal member 29 is placed on the upper surface of the buffer portion 14, the detection portion 13 is placed thereon, and the lateral U-shaped biasing member 35 is compressed while compressing the sensor fixing member 34. The detection unit 13 is pushed between the horizontal piece 34B and the upper surface of the detection unit 13 so that the fitting hole of the urging member 35 is fitted into the protrusion on the horizontal piece 34B of the sensor fixing member 34 and the upper surface of the detection unit 13. While being positioned at an appropriate position on the elastic seal member 29, the detecting portion 13 is urged toward the buffer portion 14 by the urging force of the urging member 35, and is pressed against and fixed to the upper surface of the buffer portion 14. By this pressing force, the sealing performance between the ink supply path 19 and the supply side buffer chamber 15 and between the ink discharge path 20 and the discharge side buffer chamber 16 by the elastic seal member 29 is maintained.

  Furthermore, the upstream channel 55 and the downstream channel 56 are formed in a substantially cylindrical channel space, and are formed in the same size and shape. Further, the openings of the upstream flow path 55 and the downstream flow path 56 coincide with the openings of the ink supply path 19 and the ink discharge path 20, respectively. In this example, the ink supply path 19 and the upstream flow path 55 A liquid supply path is formed, and the ink discharge path 20 and the downstream side flow path 56 form a liquid discharge path.

  With such a configuration, the ink inside the cartridge to be detected flows into the supply buffer chamber 15 from the inflow opening 22 and is supplied to the cavity 43 through the upstream flow path 55 and the ink supply path 19. The ink supplied to the cavity 43 is discharged to the discharge-side buffer chamber 16 through the ink discharge path 20 and the downstream-side flow path 56, and further discharged from the discharge-side buffer chamber 16 through the outflow opening 23. .

  Similarly to the case where the ink supply path 19 and the ink discharge path 20 are arranged symmetrically with respect to the central axis C of the cavity 43, the upstream flow path 55 and the downstream flow path 56 are arranged at the center of the cavity 43. It is formed symmetrically with respect to the axis C. As a result, a space including the cavity 43, the ink supply path 19, the upstream flow path 55, the downstream flow path 56, and the ink discharge path 20 is sandwiched between the ink supply path 19 and the ink discharge path 20. It is formed symmetrically with respect to the central axis C of the cavity existing in the region.

  Similarly to the ink supply path 19 and the ink discharge path 20, the upstream flow path 55 and the downstream flow path 56 each have a flow path area restricted with respect to the cavity 43 and a fluid mass of liquid inside. The length is set so that exists. That is, in this example, one upstream channel 55 and one downstream channel 56 are formed for one cavity 43, but one channel (the upstream channel 55 or the downstream channel 56). ) Is set to be smaller than at least half of the area of the cavity 43. The upstream flow channel 55 and the downstream flow channel 56 are set to have a certain length so that the fluid mass of the liquid exists inside.

  The supply-side buffer chamber 15 and the discharge-side buffer chamber 16 of the liquid detection device 60 are formed symmetrically with respect to the central axis C of the cavity 43. In other words, the space formed by the cavity 43, the ink supply path 19, the ink discharge path 20, the inflow channel 24, the outflow channel 25, the supply side buffer chamber 15, and the discharge side buffer chamber 16 is the center of the cavity 43. It is formed symmetrically with respect to the axis C.

  Further, the capacities of the supply-side buffer chamber 15 and the discharge-side buffer chamber 16 of the liquid detection device 60 are set to have at least 10 times the capacity of the cavity 43, respectively.

  The members included in the liquid detection device 60, in particular the cavity plate 41, the vibration plate 42, and the flow path forming plate 18, are formed of the same material and are integrally formed by firing each other. In this manner, the plurality of substrates are baked and integrated to facilitate handling of the liquid detection device 60. Further, by forming each member with the same material, it is possible to prevent the occurrence of cracks due to the difference in linear expansion coefficient.

  As a material of the piezoelectric layer 47, it is preferable to use lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), or a lead-less piezoelectric film that does not use lead. As a material for the cavity plate 41, it is preferable to use zirconia or alumina. The diaphragm 42 is preferably made of the same material as the cavity plate 41. For the upper electrode 49, the lower electrode 46, the upper electrode terminal 45, and the lower electrode terminal 44, a conductive material, for example, a metal such as gold, silver, copper, platinum, aluminum, or nickel can be used.

  FIG. 5 is a view showing an ink cartridge of the present invention provided with the liquid detection device, and FIG. 6 is a view showing an example of a mounting portion of the liquid detection device with respect to the ink cartridge.

  FIG. 5 shows an ink cartridge (liquid container) 70 to which the above-described liquid detection device 60 is mounted. The ink cartridge 70 is an ink delivery port (liquid delivery port) for sending the ink stored inside to the outside. A container body 72 having 71 is provided.

  As shown in FIG. 6, the entire liquid detection device 60 is mounted on a container body 72, and the buffer portion 14 is attached to the rectangular opening 26 formed on the wall surface 27 of the container body 72 by an adhesive 28 or the like. It is attached in a liquid-tight manner. At this time, the detection unit 13 of the liquid detection device 60 is arranged outside the container main body 72, and the inflow opening 22 and the outflow opening 23 of the buffer unit 14 are arranged to open inside the container main body 72.

  The inside of the container main body 72 (returning to FIG. 5) constitutes a main portion of the entire internal space of the container main body 72 and stores a main storage chamber (liquid storage chamber) 75 for storing ink, and this main storage. The main storage chamber 75 and the sub storage chamber 76 are separated from each other. The sub storage chamber (liquid delivery space) 76 has a smaller volume than the chamber 75. The auxiliary storage chamber 76 is located closer to the ink delivery port 71 than the main storage chamber 75 in the direction of ink flow when ink is consumed.

  The inflow opening 22 of the liquid detection device 60 is opened at a position communicating with the main storage chamber 75, and the outflow opening 23 is arranged to open to the sub storage chamber 76 that is the liquid delivery space. Thus, the supply-side buffer chamber 15 communicates with the main storage chamber 75 that constitutes a main portion of the internal space of the container main body 72 and stores the liquid, and the discharge-side buffer chamber 16 is connected to the container Of the internal space of the main body 72, the liquid stored inside is communicated with a liquid delivery space communicating with an ink delivery port 71 for delivering the liquid to the outside.

  A sealed auxiliary flow path 77 is formed inside the main storage chamber 75, and an auxiliary flow path inlet 77 a is formed on the lower end side of the auxiliary flow path 77. The auxiliary flow path inlet 77 a is located at the lower end inside the main storage chamber 75. In addition, the inflow opening 22 of the liquid detection device 60 communicates with the upper end portion of the auxiliary flow path 77, and the inflow opening 22 constitutes the outlet of the auxiliary flow path 77.

  As described above, the inflow opening 22 of the liquid detection device 60 communicates with the main storage chamber 75 through the auxiliary flow path 77, and the outflow opening 23 communicates with the ink delivery port 71 through the sub storage chamber 76. As a result, the ink stored in the main storage chamber 75 flows into the supply side buffer chamber 15 from the inflow opening 22 through the auxiliary flow path 77 and is supplied to the cavity 43 through the upstream flow path 55 and the ink supply path 19. Is done. The ink supplied to the cavity 43 is discharged to the discharge-side buffer chamber 16 through the ink discharge path 20 and the downstream-side flow path 56, and further flows from the discharge-side buffer chamber 16 to the outflow opening 23 and the auxiliary storage chamber 76. Then, the ink is discharged from the ink outlet 71 and supplied to the recording head 12.

  As described above, in this embodiment, the entire amount of ink sent to the ink delivery port 71 through the sub-reservoir chamber 76 passes through the ink supply path 19 and the ink discharge path 20 of the liquid detection device 60 in advance. Has been.

  Next, the operation for detecting the liquid in the liquid container will be described.

  In the ink cartridge 70 provided with the liquid detection device 60 described above, when the ink remains sufficiently in the container main body 72 and the inside of the auxiliary storage chamber 76 is filled with ink, the inside of the cavity 43 is filled with ink. be satisfied. On the other hand, when the liquid in the container main body 72 of the ink cartridge 7 is consumed and the ink in the main storage chamber 75 is exhausted, the liquid level in the sub storage chamber 76 is lowered, and is higher than the position of the cavity 43 of the liquid detection device 60. When the liquid level falls to the lower side, there is no ink in the cavity 43.

  Therefore, the liquid detection device 60 detects a difference in acoustic impedance caused by the change in this state. Thereby, the liquid detection device 60 can detect whether ink is sufficiently left in the container main body 72 or whether a certain amount of ink is consumed.

  More specifically, in the liquid detection device 60, a voltage is applied between the upper electrode 49 and the lower electrode 46 via the upper electrode terminal 45 and the lower electrode terminal 44. Then, an electric field is generated in a portion of the piezoelectric layer 47 sandwiched between the upper electrode 49 and the lower electrode 46. The piezoelectric layer 47 is deformed by this electric field. When the piezoelectric layer 47 is deformed, a flexural vibration is generated in a vibration region (region corresponding to the bottom surface portion 43 a of the cavity 43) of the vibration plate 42. When the application of voltage is canceled after the piezoelectric layer 47 is forcibly deformed in this way, the flexural vibration remains in the vibration part 61 of the liquid detection device 60 for a while.

  This residual vibration is free vibration between the vibration unit 61 of the liquid detection device 60 and the medium in the cavity 43. Therefore, by setting the voltage applied to the piezoelectric layer 47 to a pulse waveform or a rectangular wave, the resonance state between the vibrating portion 61 and the medium after the voltage is applied can be easily obtained. This residual vibration is a vibration of the vibration part 61 of the liquid detection device 60 and is accompanied by deformation of the piezoelectric layer 47. For this reason, the piezoelectric layer 47 generates a counter electromotive force with the residual vibration. This counter electromotive force is detected via the upper electrode 49, the lower electrode 46, the upper electrode terminal 45 and the lower electrode terminal 44. Since the resonance frequency can be specified by the back electromotive force detected in this way, the presence or absence of ink in the container main body 72 of the ink cartridge 7 can be detected based on this resonance frequency.

  7A and 7B show residual vibrations (free vibration) of the vibration unit 61 of the liquid detection device 60 when a drive signal is supplied to the liquid detection device 60 to forcibly vibrate the vibration unit 61. FIG. The waveform of this and the measuring method of residual vibration are shown. FIG. 7A shows a waveform when ink is present in the cavity 43 of the liquid detection device 60, while FIG. 7B shows a waveform when ink is not present in the cavity 43 of the liquid detection device 60. .

  7A and 7B, the vertical axis indicates the drive pulse applied to the liquid detection device 60 and the voltage of the back electromotive force generated by the residual vibration of the vibration unit 61 of the liquid detection device 60, and the horizontal axis indicates the elapsed time. Show time. Due to residual vibration of the vibration part 61 of the liquid detection device 60, a waveform of an analog voltage signal is generated. Next, the analog signal is converted (binarized) into a digital numerical value corresponding to the frequency of the signal. In the example shown in FIG. 7, the time for generating four pulses from the fourth pulse to the eighth pulse of the analog signal is measured.

  More specifically, after a drive pulse is applied to the liquid detection device 60 to forcibly vibrate the vibration unit 61, a voltage waveform due to residual vibration is changed from a low voltage side to a predetermined reference voltage set in advance. Count the number of crossings to the side. Then, a digital signal is generated with High between 4 counts and 8 counts, and the time from 4 counts to 8 counts is measured by a predetermined clock pulse.

  Comparing FIG. 7A and FIG. 7B, it can be seen that the time from 4 to 8 counts is longer in FIG. 7A than in FIG. 7B. In other words, the required time from 4 counts to 8 counts varies depending on the presence or absence of ink in the cavity 43 of the liquid detection device 60. The consumption state of ink can be detected using the difference in the required time.

  The reason for counting from the fourth count of the analog waveform is to start measurement after the residual vibration (free vibration) of the liquid detection device 60 is stabilized. The count from the fourth count is merely an example, and the count may be counted from an arbitrary count. Here, signals from the 4th count to the 8th count are detected, and the time from the 4th count to the 8th count is measured by a predetermined clock pulse. Based on this time, the resonance frequency can be determined. The clock pulse does not need to be measured until the eighth count, and may be counted up to an arbitrary count.

  In FIG. 7, the time from the 4th count to the 8th count is measured, but the time within different count intervals may be detected according to the circuit configuration for detecting the frequency. For example, when the ink quality is stable and the fluctuation of the peak amplitude is small, the resonance frequency may be obtained by detecting the time from the 4th count to the 6th count in order to increase the detection speed. . When the ink quality is unstable and the fluctuation of the pulse amplitude is large, the time from the 4th count to the 12th count may be detected in order to accurately detect the residual vibration.

  As described above, in the liquid detection device 60 according to the present embodiment, the vibration unit 61 of the liquid detection device 60 determines whether or not the liquid level has passed the mounting position level of the liquid detection device 60 (strictly, the position of the cavity 43). Can be detected by a change in the frequency or amplitude of the residual vibration after forcibly vibrating.

  FIG. 8 is an equivalent circuit diagram that can be simulated by approximating the vibration of the vibration unit 61 of the liquid detection device 60 as described above.

  In this figure, the inertance (Mc) of the vibration part 61 (Sensor Chip), the inertances (Ms1, Ms2) of the ink supply path 19 and the ink discharge path 20 (Hole) are coils, and the compliance of the vibration part 61 (Sensor Chip) ( Cc), the compliance of the ink (Ci) is a capacitor, the resistance (Rs1, Rs2) of the ink supply path 19 and the ink discharge path 20 (Hole) is the resistance, and the supply side where the ink supply path 19 and the ink discharge path 20 communicate with each other The buffer chamber 15 and the discharge side buffer chamber 16 are represented by grounds.

And the compliance (Cc) of the vibration part 61 is calculated | required by the structural finite element method. Further, the inertance (Mc) of the vibration unit 61 is approximated by a series system of inertance and compliance, and an approximate value can be calculated by the following approximate expression.
Mc = 1 / (4π ² ) × 1 / (f ² ) × 1 / Cc
Here, f is a natural period of the vibration part 61 and can be obtained by a structural finite element method or actual measurement.

The ink compliance (Ci) can be obtained by the following equation.
Ci = C × Vi
Here, C is the ink compression ratio, and Vi is the ink volume. The compressibility of water is 4.5e-10 / Pa.

Further, the inertance (Ms) of the ink supply path 19 and the ink discharge path 20 (Hole) can be obtained by the fluid finite element method, or when the flow path (Hole) is a cylinder, it can be obtained by the following simplified formula.
Ms = ρ × L / π / r ²
Here, ρ is the viscosity of the ink, L is the length of the flow path (Hole), and r is the radius of the flow path (Hole).

  By using the values obtained as described above, the vibration of the vibration part 61 can be simulated by approximation with the equivalent circuit of FIG.

  As a result of simulating the vibration of the vibration part 61 with such an equivalent circuit, it can be seen that when Ms1 and Ms2 and Rs1 and Rs2 are approximately equal, vibration is simple and no extra vibration mode occurs. Therefore, in the present invention, the space formed by the cavity 43, the ink supply path 19, and the ink discharge path 20 is formed symmetrically with respect to the central axis C of the cavity 43.

  In addition, the requirement that the supply side buffer chamber 15 and the discharge side buffer chamber 16 function as buffers is that the buffer chambers 15, 16 are configured so that the pressure in the buffer chambers 15, 16 is hardly increased by the vibration of the vibration part 61. It is preferable that the compliance of 16 is 10 times or more the compliance (Cc) of the vibration part 61. In order not to generate extra vibration, the inertance of the buffer chambers 15 and 16 is preferably set to 1/10 or less of the inertance (Ms) of the flow path (Hole).

  As described above, according to the liquid detection device 60 and the ink cartridge 70 according to the present embodiment, the supply side buffer chamber 15 communicating with the cavity 43 via the upstream side flow path 55 and the ink supply path 19, and the above Since the buffer section 14 having the discharge side buffer chamber 16 communicating with the cavity 43 via the downstream side flow path 56 is provided, the supply of ink to the cavity 43 is performed via the upstream side flow path 55 and the ink supply path 19. Since the ink is discharged from the cavity 43 via the downstream flow path 56 and the ink discharge path 20, when the liquid detection device 60 is mounted on the ink cartridge 70 or the like, the ink is stored in the ink storage space. Without directly exposing the cavity 43 of the liquid detection device, the ink is supplied to the cavity 43 via the upstream flow path 55 and the ink supply path 19. It can be supplied.

  As described above, by configuring the ink to flow through the upstream flow path 55, the ink supply path 19, the downstream flow path 56, and the ink discharge path 20 of the liquid detection device 60 when the ink is consumed, the cavity is temporarily assumed. Even if a bubble enters the inside of the nozzle 43, the bubble is pushed out of the cavity 43 by the flow of ink. As a result, it is possible to prevent erroneous detection of the liquid detection device 60 due to air bubbles remaining in the cavity 43. In this way, the detection accuracy of the liquid detection device 60 is improved, and the remaining liquid is reduced, leading to a reduction in industrial waste.

  Further, since it is not necessary to expose the cavity 43 to the ink containing space, it is possible to prevent a meniscus from being formed in the cavity 43 when the liquid surface passes. As a result, erroneous detection of the liquid detection device 60 due to ink remaining in the cavity 43 can be prevented. In addition, since the cavity 43 is not a space exposed toward the ink storage space but a space partitioned from the storage space by the flow path forming plate 18, depending on the change in the ink liquid level, the presence or absence of ink, and the like, The difference in residual vibration remaining in the vibration part 61 when the vibration part 61 is forcibly vibrated is increased, the detection sensitivity is increased, the detection accuracy can be increased, and erroneous detection can be prevented.

  In addition, since the elastic seal member 29 is provided between the detection unit 13 and the buffer unit 14 and seals between the detection unit 13 and the buffer unit 14, the detection accuracy can be ensured and the manufacturing process can be ensured. Simplify.

  That is, for example, when the space between the buffer unit 14 and the detection unit 13 is sealed with an adhesive or the like, the adhesive protrudes into the channel in the channel space where the cavity 43 communicates with the upstream channel 55 and the downstream channel 56. There is a problem that bubbles easily adhere to the protruding adhesive and are difficult to be removed, affecting residual vibration on the bottom surface of the cavity 43 and adversely affecting detection accuracy. Accordingly, since the adhesive must be managed so as not to protrude into the flow path, there has been a problem that the bonding process becomes extremely complicated.

  On the other hand, in this embodiment, since the gap between the detection unit 13 and the buffer unit 14 is sealed by the elastic seal member 29, there is no problem of the sticking out of the adhesive into the flow path described above, and there is no bubble. This eliminates the problem of deterioration in detection accuracy due to adhesion and the complexity of the process due to the management of the protruding adhesive.

  Moreover, since the elastic seal member 29 is disposed at a place other than the flow path wall of the flow path space where the cavity 43 communicates with the upstream flow path 55 and the downstream flow path 56, Since vibration is not transmitted to the elastic seal member 29 itself via ink, it is possible to prevent a decrease in detection accuracy due to vibration generated in the elastic seal member 29 affecting residual vibration on the bottom surface of the cavity 43.

  That is, for example, when the elastic seal member 29 is exposed in the flow path space between the upstream flow path 55 or the downstream flow path 56 and the cavity 43, the vibration of the bottom surface of the cavity 43 is caused by the elastic seal member 29 itself through the ink. In contrast, the vibration mode may be complicated, for example, the vibration of the elastic seal member 29 may affect the vibration of the bottom surface of the cavity 43 through the ink. Therefore, by placing the elastic seal member 29 at a place other than the flow path wall of the flow path space where the cavity 43 and the upstream flow path 55 and the downstream flow path 56 communicate with each other, such a situation occurs. Therefore, it is possible to prevent a decrease in detection accuracy.

  Further, the buffer portion 14 is formed with a flow path protrusion 58 in which the upstream flow path 55 and the downstream flow path 56 open, and the elastic seal member 29 is formed at the outer periphery of the flow path protrusion 58. Since the space between the detection unit 13 and the buffer unit 14 is sealed, the surfaces of the flow channel projections 58 where the upstream flow channel 55 and the downstream flow channel 56 open are opposed to the cavity 43 of the detection unit 13 and joined. By doing so, the upstream flow path 55 and the downstream flow path 56 are communicated with the cavity 43 to form a flow path, and the elastic seal member 29 is sealed around the facing portion, whereby the elastic seal member 29 is Sealing can be surely performed without exposing to the flow path.

  Further, since the annular protrusion 57 surrounding the openings of the upstream flow path 55 and the downstream flow path 56 is formed on the surface of the flow path protrusion 58 that faces the detection unit 13, the flow path protrusion The surface where the upstream flow path 55 and the downstream flow path 56 of the part 58 are opened faces the cavity 43 of the detection unit 13, and the upstream flow path 55 and the downstream flow path 56 are communicated with the cavity 43. At the time of forming, the annular protrusion 57 is in close contact with the detecting portion 13, and the minute gap due to the flatness of the member at the joint portion between the cavity 43 and the flow path protruding portion 58 is extremely reduced, and the sealing performance is further improved. The contact between the elastic seal member 29 and the ink is almost eliminated, and the vibration of the elastic seal member 29 via the ink is almost eliminated, so that a decrease in detection accuracy can be reliably prevented.

  Further, in the present embodiment, the upstream flow path 55 and the downstream flow path 56 are formed symmetrically with respect to the central axis C of the cavity 43, so that the upstream where the vibration of the bottom surface of the cavity 43 is propagated. The space shape of the space formed including the side channel 55 and the downstream channel 56 is simplified, and the vibration mode of residual vibration remaining on the bottom surface of the cavity 43 is also simplified. For this reason, it becomes easy to perform simulation of residual vibration when the bottom surface of the cavity 43 is forcibly vibrated, and the difference between the design and the actual is reduced, so that adjustment work can be reduced and detection accuracy can be improved. It becomes possible.

  Similarly, since the ink supply path 19 and the supply side communication port 32 and the ink discharge path 20 and the discharge side communication port 33 are formed symmetrically with respect to the central axis C of the cavity 43, the cavity It becomes easy to simulate residual vibration when the bottom surface is forcibly vibrated, and the difference between the design and the actual is reduced, so that adjustment work can be reduced and detection accuracy can be improved.

  Further, since the space forming the cavity 43 is substantially cylindrical, the shape of the cavity 43, which is the space through which the vibration of the bottom surface of the cavity 43 propagates, is further simplified, and the vibration mode of residual vibration remaining on the bottom surface of the cavity 43. Also simplify. And it becomes very easy to simulate the residual vibration when the bottom surface of the cavity 43 is forcibly vibrated, the difference between the design and the actual is reduced, the adjustment work is reduced, and the detection accuracy can be improved. .

  In addition, in the present embodiment, the upstream flow channel 55 and the downstream flow channel 56 are set to have a length such that the flow channel area is restricted with respect to the cavity 43 and the fluid mass of the ink is present inside. Therefore, an appropriate flow path resistance is generated in the upstream flow path 55 and the downstream flow path 56, and therefore pressure fluctuations in the cavity 43 caused by vibration of the bottom surface of the cavity 43 are caused by the supply side buffer chamber 15 and the discharge side buffer. It is possible to prevent diffusion into the chamber 16 and generate appropriate residual vibration to improve and secure detection accuracy.

  Furthermore, since the ink supply path 19 and the ink discharge path 20 are respectively narrowed in flow path area with respect to the cavity 43 and set to have a fluid mass of ink inside, the ink supply path Appropriate flow path resistance is generated in the path 19 and the ink discharge path 20, so that the pressure fluctuation in the cavity 43 caused by the vibration of the bottom surface of the cavity 43 is prevented from diffusing into both the buffer chambers 15 and 16. Residual vibration can be generated to improve and secure detection accuracy.

  In the present embodiment, since the detecting unit 13 is urged toward the buffer unit 14 and the urging member 35 is provided to fix the detecting unit 13 to the buffer unit 14. The detection unit 13 is securely attached to the buffer unit 14 by the urging force, and the elastic seal member 29 is compressed by the urging force and is brought into close contact with the detection unit 13 and the buffer unit 14 so that the sealing is reliably performed. Further, even if the elastic seal member 29 is compressed and hardly deformed by the urging force, and the vibration of the bottom surface of the cavity 43 is transmitted to the elastic seal member 29 itself through the ink, the elastic seal member 29 itself is difficult to vibrate. Therefore, a decrease in detection accuracy due to vibration of the elastic seal member 29 can be effectively prevented.

  In this embodiment, the attachment target member has the supply-side buffer chamber 15 communicating with the cavity 43 via the upstream flow path 55 as the upstream space, and via the downstream flow path 56 as the downstream space. Since the buffer section 14 has the discharge-side buffer chamber 16 communicating with the cavity 43, the upstream-side flow channel 55 and the downstream-side flow channel 56 through which ink enters and exits the cavity 43 are respectively connected to the supply-side buffer chamber 15 and the discharge side. Since it opens to the buffer chamber 16 and does not directly open to the ink storage space of the container main body 72, even if bubbles are generated in the ink storage space due to ink vibration or the like, the bubbles are supplied to the supply-side buffer chamber 15. Or once trapped in the discharge-side buffer chamber 16 and difficult to enter the cavity 43. Therefore, erroneous detection of the liquid detection device 60 due to air bubbles remaining in the cavity 43 can be prevented. In addition, since the liquid detection device 60 is disposed near the bottom of the ink cartridge 70, the effect of preventing the entry of bubbles is further enhanced.

  In addition, the upstream flow path 55 and the downstream flow path 56 through which ink enters and exits the cavity 43 do not directly open to the ink storage space of the container main body 72, but each supply side buffer chamber 15 and discharge side. Since the buffer chamber 16 is open, the pressure of the ink generated in the ink storage space in the ink cartridge 70 does not directly act on the cavity 43. Therefore, the liquid detection device 60 may be erroneously affected by the pressure due to the vibration of the ink. Detection can be prevented.

  Furthermore, since the supply side buffer chamber 15 and the discharge side buffer chamber 16 of the liquid detection device 60 are formed symmetrically with respect to the central axis C of the cavity 43, the supply side buffer chamber 15 and the discharge side buffer chamber 16. Are simplified, the shapes of the members constituting both the buffer chambers 15 and 16 are simplified, the manufacture is facilitated, and the members can be miniaturized.

  Moreover, the supply-side buffer chamber 15 and the discharge-side buffer chamber 16 of the liquid detection device 60 each have a capacity at least 10 times the capacity of the cavity 43, so that the ink storage space in the ink cartridge 70 is obtained. The ink pressure fluctuation generated in the ink hardly affects the sensor characteristics of the liquid detection device 60, and the erroneous detection of the liquid detection device 60 due to the influence of pressure due to ink vibration or the like can be prevented. Further, since the pressure in the buffer chambers 15 and 16 does not increase due to the vibration of the bottom surface of the cavity 43, no extra vibration is generated, and the vibration mode of the residual vibration remaining on the bottom surface of the cavity 43 is simplified and the detection accuracy is improved. It becomes possible to make it.

  Further, the buffer unit 14 is attached to a container main body 72 having an ink delivery port 71 for sending ink stored inside to the outside, and the supply-side buffer chamber 15 is a main part of the internal space of the container main body 72. The discharge-side buffer chamber 16 communicates with an ink delivery port 71 that sends out the ink stored inside the internal space of the container main body 72 to the outside. The ink stored in the main storage chamber 75 of the container main body 72 flows from the inlet of the supply-side buffer chamber 15 of the liquid detection device 60. The ink is discharged from the outlet of the discharge-side buffer chamber 16 and sent to the ink delivery port 71 of the container main body 72, and is sent to the ink delivery port 71 of the container main body 72. The total amount in advance to the liquid detection device the supply side buffer chamber 15 of 60, for passing through the cavity 43 and the discharge side buffer chamber 16, it is possible to reliably detect the ink consumption.

  Further, according to the liquid detection device 60, since the downstream flow path 56 and the ink discharge path 20 are formed in accordance with the region corresponding to the cavity 43, the bubbles that have entered the cavity 43 can be reliably discharged. Can do.

  Further, in the ink cartridge 70, the interior of the container main body 72 is partitioned into a main storage chamber 75 and a sub storage chamber 76 that are separated from each other, and the main body 72 is separated via the inflow opening 22 and the outflow opening 23 of the liquid detector 60. The storage chamber 75 and the sub storage chamber 76 are connected to each other, and the cavity 43 of the liquid detection device 60 is disposed at the upper end portion of the sub storage chamber 76.

  For this reason, the time when the ink in the main storage chamber 75 runs out can be reliably detected by the liquid detection device 60, so that the user can be notified that the ink end is approaching. Further, it is possible to notify the user of the number of printable sheets with the remaining ink based on the previously known amount of ink in the sub-reservoir chamber 76, and the printing paper is wasted because the ink runs out in the middle of one page. Can be prevented.

  Further, according to the ink cartridge 70, the sealed auxiliary flow path 77 is formed inside the main storage chamber 75, and the auxiliary flow path inlet 77a of the auxiliary flow path 77 is positioned at the lower end of the main storage chamber 75. The inflow opening 22 of the liquid detection device 60 is communicated with the upper end portion of the auxiliary flow path 77. For this reason, bubbles generated in the main storage chamber 75 are unlikely to enter the auxiliary flow path 77, and bubbles can be prevented from entering the cavity 43 of the liquid detection device 60.

  Furthermore, according to the ink cartridge 70, since the inside of the sub storage chamber 76 is filled with ink until all the ink in the main storage chamber 75 is consumed, vibration is applied to the ink cartridge 70. Even in this case, as long as ink remains in the main storage chamber 75, the liquid level does not shake in the sub storage chamber 76. Accordingly, it is possible to prevent the liquid detection device 60 from erroneously detecting due to the fluctuation of the liquid level.

  Further, according to the liquid detection device 60, since the range in which the vibrating unit 61 and the ink are in contact is limited to the range in which the cavity 43 exists, it is possible to pinpoint ink detection. Thereby, the ink level can be detected with high accuracy.

  In addition, since the substantially entire region corresponding to the cavity 43 is covered with the main body 46a of the lower electrode 46, the difference between the deformation mode during forced vibration and the deformation mode during free vibration is reduced. Further, since the vibration part 61 of the liquid detection device 60 has a symmetrical shape with respect to the center of the liquid detection device 60, the rigidity of the vibration part 61 is substantially isotropic when viewed from the center.

  For this reason, generation | occurrence | production of the unnecessary vibration which may arise from the asymmetry of a structure is suppressed, and the output fall of the counter electromotive force by the difference in the deformation mode between the time of forced vibration and free vibration is prevented. Thereby, the detection accuracy of the resonance frequency of the residual vibration in the vibration unit 61 of the liquid detection device 60 is improved, and the detection of the residual vibration of the vibration unit 61 is facilitated.

  In addition, since substantially the entire region corresponding to the cavity 43 is covered with the main body 46a of the lower electrode 46 having a diameter larger than that of the cavity 43, generation of unnecessary vibration due to the positional deviation of the lower electrode 46 during manufacturing is generated. It is prevented, and the fall of detection accuracy can be prevented.

  Further, the entire hard but fragile piezoelectric layer 47 is disposed inside the region corresponding to the cavity 43, and the piezoelectric layer 47 does not exist at a position corresponding to the peripheral edge 43 b of the cavity 43. For this reason, there is no problem of a crack of the piezoelectric film at a position corresponding to the peripheral edge of the cavity.

  9 and 10 show a second embodiment of a liquid detection device 60A to which the present invention is applied.

  In this example, the detection unit 13 does not have the flow path forming plate 18, and the upstream flow path 55 and the downstream flow path 56 communicate directly with the cavity 43 opened on the lower surface. That is, a substantially circular channel protrusion 58 is formed on the upper surface of the buffer unit 14 so as to be inscribed in the inner periphery of the cavity 43 in plan view, and the upstream channel 55 and the downstream channel 56. And are formed. In addition, a circular annular ridge 57 that is slightly larger than the opening edge of the cavity 43 is formed. Further, the elastic seal member 29 is formed with a circular opening so as to be fitted to the circular flow path protrusion 58. The top surface of the flow path protrusion 58 of the buffer unit 14 is fixed so as to face the lower surface of the cavity plate 41 of the detection unit 13.

  According to the second embodiment, since the flow path forming plate 18 is omitted, the number of parts is so small that the detection device itself can be downsized. Further, since the upstream flow path 55 and the downstream flow path 56 are formed close to the inner peripheral edge of the cavity 43, the turbulent flow and stagnation during the inflow and outflow of ink are reduced, and the ink flows smoothly. In addition, the discharge of bubbles is improved. The rest is the same as in the first embodiment, and the same reference numerals are given to the same parts. Also in this embodiment, the same effects as those of the first embodiment are achieved.

  FIG. 11 is a third embodiment of an ink cartridge to which the present invention is applied.

  The ink cartridge 70 </ b> A is an example in which the liquid detection device 60 </ b> A does not include the buffer unit 14 and is configured only by the detection unit 13. The ink cartridge 70 </ b> A includes an upstream channel 55 that communicates the cavity 43 of the detection unit 13 and the auxiliary channel 77 of the container main body 72 with the wall surface of the container main body 72, and A downstream flow path 56 that allows the storage chamber 76 to communicate is formed. A sensor fixing member 34 for fixing the detection unit 13 is formed on the outer surface of the container main body 72, and the elastic seal member 29 and the detection unit are formed in the same manner as in the first and second embodiments described above. 13 is positioned and fixed to the outer surface of the container main body 72.

  In this example, the auxiliary flow path 77 functions as an upstream space, that is, a buffer chamber, and the auxiliary storage chamber 76 functions as a downstream space, that is, a buffer chamber. The rest is the same as in the first and second embodiments, and the same reference numerals are given to the same parts. Also in this embodiment, the same operational effects as the first and second embodiments are obtained.

1 is a perspective view illustrating a schematic configuration of an ink jet recording apparatus in which an ink cartridge including a liquid detection device to which the present invention is applied is used. It is sectional drawing along the AA line in FIG. 3 of the liquid detection apparatus with which this invention was applied. It is a figure which shows the detection part of the said liquid detection apparatus, (a) is a top view, (b) is the bottom view. It is BB sectional drawing in FIG. 2 which shows the buffer part of the said liquid detection apparatus. It is a figure which shows the ink cartridge provided with the said liquid detection apparatus, (a) is a side view, (b) is the front view. It is an expanded sectional view which shows the attachment part of the liquid detection apparatus of the said ink cartridge. It is a figure which shows the drive pulse waveform and back electromotive force waveform in the liquid detection apparatus by one Embodiment of this invention, (a) is a wave form diagram in case ink exists in a cavity, (b) is ink in a cavity. Waveform diagram when it does not exist. It is a figure which shows an example of the equivalent circuit which approximates and simulates the vibration of a vibration part. It is 2nd Example of the liquid detection apparatus with which this invention was applied. It is DD sectional drawing in FIG. 9 which shows the buffer part of the said 2nd Example. It is 3rd Example of the ink cartridge to which this invention was applied. It is the figure which showed the conventional liquid detection apparatus, (a) is a top view, (b) is sectional drawing along the BB line of (a), (c) is CC line of (a). FIG. FIG. 13 is a cross-sectional view of a conventional ink cartridge including the conventional liquid detection device shown in FIG. 12.

Explanation of symbols

1: Carriage 2: Carriage motor 3: Timing belt 4: Guide member 5: Platen 6: Recording paper 7: Ink cartridge 10: Pump unit 11: Wiping means 12: Recording head 13: Detection unit 14: Buffer unit 15: Supply side Buffer chamber 16: Discharge-side buffer chamber 17: Piezoelectric element 18: Flow path forming plate 19: Ink supply path 20: Ink discharge path 21: Partition wall 22: Inflow opening 23: Outflow opening 26: Opening 27: Wall surface 28: Adhesive 29: Elastic seal member 31: Cap member 32: Supply side communication port 33: Discharge side communication port 34: Sensor fixing member 34A: Vertical piece 34B: Horizontal piece 35: Energizing member 37: Protrusion 40: Vibration cavity forming base 40a: First surface 40b: Second surface 41: Cavity plate 42: Vibration plate 43: Cavity 43a: Bottom surface portion 43b: Edge 44: Lower electrode terminal 45: Upper electrode terminal 46: Lower electrode 46a: Main body part 46b: Extension part 46c: Notch part 47: Piezoelectric layer 47a: Main body part 47b: Projection part 48: Auxiliary electrode 49: Upper electrode 49a : Main part 49b: Extension part 55: Upstream channel 56: Downstream channel 57: Annular ridge 58: Channel projection 60: Liquid detection device 60A: Liquid detection device 61: Vibration unit 70: Ink cartridge 70A : Ink cartridge 71: Ink delivery port 72: Container body 75: Main reservoir chamber 76: Sub reservoir chamber 77: Auxiliary channel 77 a: Auxiliary channel inlet 106: Actuator 160: Piezoelectric layer 161: Opening 162: Cavity 164: Upper electrode 166: Lower electrode 168: Upper electrode terminal 170: Lower electrode terminal 172: Auxiliary electrode 176: Diaphragm 178: Substrate 180: Ink cart Ridge 181: Container body

Claims (6)

A cavity having a first surface and a second surface facing each other and receiving a medium to be detected is formed so as to open to the first surface side, and a bottom surface of the cavity is formed so as to be able to vibrate. A vibration cavity forming base,
Detection comprising: a first electrode formed on the second surface side of the vibration cavity forming base; a piezoelectric layer laminated on the first electrode; and a piezoelectric element having a second electrode laminated on the piezoelectric layer Equipment,
The detection target is mounted, and an attachment target member having an upstream space communicating with the cavity via an upstream flow path, and a downstream space communicating with the cavity via a downstream flow path,
An elastic seal member that is interposed between the detection device and the attachment target member and seals between the detection device and the attachment target member;
The attachment target member is formed with a projecting protrusion protruding from the upstream channel and the downstream channel,
In a planar view, the channel protrusion has a track shape, and the upstream channel and the downstream channel are formed inside the track shape,
The elastic sealing member has the cavity and the upstream channel and the downstream flow passage is located at other than the channel walls of the flow path space which is in communication, the track shape of the passage protrusion An attachment structure for a liquid detection device, wherein a gap between the detection device and the attachment target member is sealed at an outer periphery of the liquid detection device. On the surface facing the said detector of the flow path projection, the liquid detection device according to claim 1, wherein the annular ridge surrounding the opening of the upstream channel and the downstream flow path is formed Mounting structure. Attachment structure of the liquid detection device according to the detecting device to claim 1 or 2 and a biasing member for fixing the detector with respect to the mounting object member by biasing toward the mounting object member . A container body having a liquid delivery port for delivering the liquid stored inside to the outside;
A detection device attached to the container body for detecting the liquid inside,
The detection device has a first surface and a second surface facing each other, and a cavity for receiving a medium to be detected is formed so as to open toward the first surface, and the bottom surface of the cavity vibrates. A vibration cavity forming base formed in a possible manner;
Detection comprising: a first electrode formed on the second surface side of the vibration cavity forming base; a piezoelectric layer laminated on the first electrode; and a piezoelectric element having a second electrode laminated on the piezoelectric layer And configured with
The container body has an upstream side space communicating through the cavity and the upstream channel, and a downstream space which communicates via the cavity and the downstream flow path,
The container body is formed with a channel protrusion projecting from the upstream channel and the downstream channel,
In a planar view, the channel protrusion has a track shape, and the upstream channel and the downstream channel are formed inside the track shape,
Interposed between the detector and the container body further comprising an elastic sealing member for sealing between said detector and said container body,
The elastic sealing member, the cavity and the upstream channel and the downstream flow path are arranged at other than the flow path wall of a flow path space which is in communication, the track shape of the passage protrusion A liquid container in which a gap between the detection device and the container main body is sealed at an outer periphery of the container.   The liquid container according to claim 4, wherein an annular ridge surrounding the opening of the upstream channel and the downstream channel is formed on a surface of the channel projection facing the detection device.   The liquid container according to claim 4, further comprising a biasing member that fixes the detection device to the attachment target member by biasing the detection device toward the attachment target member.

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