Liquid ejecting head and liquid ejecting apparatus

A liquid ejecting head includes: a nozzle; a flow path member in which a flow path communicating with the nozzle is formed and which has an inner wall surface defining the flow path and an outer wall surface that faces away from the flow path with respect to the inner wall surface; and a temperature sensor disposed on a part of the outer wall surface and configured to detect a temperature of the liquid in the flow path. The flow path includes a narrowed region having a narrow width in a second direction orthogonal to a first direction in a direction in which the flow path extends, and the temperature sensor is disposed on a portion of the outer wall surface that forms the narrowed region.

The present application is based on, and claims priority from JP Application Serial Number 2021-009363, filed on Jan. 25, 2021, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND

1. Technical Field

The present disclosure relates to a liquid ejecting head and a liquid ejecting apparatus.

2. Related Art

A flow path through which a liquid flows is formed inside a liquid ejecting head that ejects a liquid such as an ink. The liquid ejecting head includes a temperature sensor that detects a temperature of the liquid in the flow path. In JP-A-2020-142379, a substrate in which the flow path is defined is provided with an opening communicating with the flow path. A temperature detection element is disposed on a metal plate that seals this opening.

Since a flow velocity of the liquid decreases in a region in contact with an inner wall surface of the flow path, a temperature of the liquid in the vicinity of the inner wall surface tends to be lower than a temperature of the liquid flowing in the center of the flow path away from the inner wall surface. For this reason, when the temperature of the liquid in the flow path is detected from an outer wall surface on a side opposite to the inner wall surface, there has been a risk of decreased accuracy of temperature detection of the liquid.

SUMMARY

According to an aspect of the present disclosure, a liquid ejecting head includes: a nozzle for ejecting a liquid; a flow path member in which a flow path communicating with the nozzle is formed and which has an inner wall surface defining the flow path and an outer wall surface on a side opposite to the flow path with respect to the inner wall surfaces; and a temperature sensor disposed on a part of the outer wall surface and detecting a temperature of the liquid in the flow path. The flow path includes a narrowed region having a narrow width in a second direction orthogonal to a first direction in a direction in which the flow path extends. The temperature sensor is disposed on a portion of the outer wall surface that forms the narrowed region.

According to another aspect of the present disclosure, a liquid ejecting apparatus includes: the liquid ejecting head as described above; and a liquid storage portion storing the liquid supplied to the liquid ejecting head.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

Hereinafter, a mode for carrying out the present disclosure will be described with reference to the drawings. However, dimensions and scales of each portion in each drawing are appropriately different from actual dimensions and scales. In addition, since embodiments to be described below are suitable specific examples of the present disclosure, various technically preferable limitations are added, but the scope of the present disclosure is not limited to these forms unless it is stated in the following description that the present disclosure is particularly limited.

In the following description, three directions that intersect each other may be described as an X-axis direction, a Y-axis direction, and a Z-axis direction. The X-axis direction includes an X1 direction and an X2 direction, which are directions opposite to each other. The X-axis direction is an example of a third direction. The Y-axis direction includes a Y1 direction and a Y2 direction, which are directions opposite to each other. The Y-axis direction is an example of a first direction. The Z-axis direction includes a Z1 direction and a Z2 direction, which are directions opposite to each other. The Z1 direction is a downward direction, and the Z2 direction is an upward direction. The Z1 direction is the direction of gravity. The Z-axis direction is an example of a second direction. In addition, in the present specification, “upper” and “lower” are used. “Upper” and “lower” correspond respectively to “upper” and “lower” in a normal use state of a liquid ejecting apparatus1.

The Z-axis direction is a direction in a vertical direction. The X-axis, the Y-axis, and the Z-axis directions are typically orthogonal to each other, but are not limited thereto. The Z-axis direction is not limited to the vertical direction.

FIG.1is a schematic view illustrating a configuration of the liquid ejecting apparatus1according to a first embodiment. The liquid ejecting apparatus1is an ink jet printing apparatus that ejects an ink, which is an example of a “liquid”, as droplets onto a medium PA. The liquid ejecting apparatus1is a serial type printing apparatus. The liquid ejecting apparatus1includes a plurality of liquid ejecting heads10. The liquid ejecting head10ejects the ink toward the medium PA while moving in a width direction of the medium PA. The medium PA is typically printing paper. Note that the medium PA is not limited to printing paper, and may be a printing target of any material, such as a resin film or cloth.

As illustrated inFIG.1, the liquid ejecting apparatus1includes a liquid container2that stores the ink. Examples of a specific aspect of the liquid container2include a cartridge that is attachable to and detachable from the liquid ejecting apparatus1, a bag-shaped ink pack formed of a flexible film, and an ink tank that can be replenished with the ink. Note that any appropriate type of the ink may be stored in the liquid container2. The liquid container2is an example of a liquid storage portion.

The liquid container2includes a first liquid container2aand a second liquid container2b. A first ink is stored in the first liquid container2a. A second ink of a type different from that of the first ink is stored in the second liquid container2b. For example, the first ink and the second ink are inks of colors different from each other. Note that the first ink and the second ink may be the same type of ink.

The liquid ejecting apparatus1includes a control unit3, a medium transport mechanism4, a carriage5, and a carriage transport mechanism6. The control unit3controls an operation of each element of the liquid ejecting apparatus1. The control unit3includes, for example, a processing circuit, such as a central processing unit (CPU) or a field programmable gate array (FPGA), and a storage circuit, such as a semiconductor memory. Various programs and various data are stored in the storage circuit. The processing circuit realizes various forms of control by executing the program and appropriately using the data.

The medium transport mechanism4is controlled by the control unit3to transport the medium PA in a transport direction DM. The medium transport mechanism4includes a transport roller that transports the medium PA and a motor that rotates the transport roller. Note that the medium transport mechanism4is not limited to having a configuration using the transport roller, and may have, for example, a configuration using a drum or an endless belt that transports the medium PA in a state in which the medium PA clings onto an outer peripheral surface thereof by an electrostatic force or the like.

The plurality of liquid ejecting heads10are mounted on the carriage5. The carriage transport mechanism6is controlled by the control unit3to reciprocate the carriage5in the width direction of the medium PA. The carriage transport mechanism6may include, for example, an endless belt laid over a plurality of rollers spaced apart from each other in the width direction of the medium PA. Note that the liquid container2may be configured to be mounted on the carriage5and be transported together with the plurality of liquid ejecting heads10.

FIG.2is an exploded perspective view illustrating the liquid ejecting head10.FIG.3is a bottom view of the liquid ejecting head10. The liquid ejecting head10includes a plurality of head chips11provided with nozzles N, a holder12holding the head chips11, a flow path structure13in which a flow path of the ink is formed, a relay substrate14disposed on an upper portion of the flow path structure13, and a connector15provided on the relay substrate14.

As illustrated inFIG.3, the plurality of head chips11are disposed at a bottom portion of the liquid ejecting head10. The plurality of head chips11are held by the holder12. The head chip11is provided with a plurality of nozzles N that eject a liquid. The nozzles N are arranged in a predetermined direction to constitute nozzle rows16. A plurality of nozzle rows16are provided so as to correspond to types of inks.

As illustrated inFIG.2, the flow path structure13is disposed on the holder12. The flow path through which the ink flows is formed in the flow path structure13. The flow path structure13includes a plurality of flow path substrates17. The plurality of flow path substrates17are laminated in a plate thickness direction. For example, grooves and openings are formed in the flow path substrates17. The flow paths are formed by these grooves and openings.

The liquid ejecting apparatus1employs an ink circulation method that circulates the ink. The flow path structure13is provided with ink supply ports18for introducing the ink into the flow path structure13and ink discharge ports19for discharging the ink from the flow path structure13.

In addition, a temperature sensor20is disposed on the upper portion of the flow path structure13. Details will be described later.

The relay substrate14covers the upper portion of the flow path structure13. The relay substrate14is provided with a plurality of electrical wiring lines. The head chips11and the temperature sensor20are electrically coupled to the electrical wiring lines provided on the relay substrate14.

The connector15projects upward from the relay substrate14. The connector15is electrically coupled to an external electrical component of the liquid ejecting head10. The head chips11and the temperature sensor20are electrically coupled to the control unit3via the connector15.

FIG.4is a schematic view illustrating a flow path30of an ink of the liquid ejecting apparatus1. InFIG.4, the flow path30through which one type of ink flows is illustrated. The flow path30of the ink is provided for each type of ink. The liquid container2, a pump31, a heater32, filters33, and common liquid chambers34are coupled to the flow path30. The flow path30includes a supply flow path35and a collection flow path36. The supply flow path35is a flow path for supplying the ink from the liquid container2to the common liquid chamber34. The collection flow path36is a flow path for collecting the ink from the common liquid chamber34in the liquid container2.

The pump31is coupled to the downstream of the liquid container2and transfers the ink stored in the liquid container2. The heater32is coupled to the downstream of the pump31and heats the ink to a predetermined temperature. Note that the heater32may be configured to heat the ink stored in the liquid container2. By adjusting a temperature of the ink, the ink viscosity can be adjusted. The liquid container2, the pump31, and the heater32are disposed outside the liquid ejecting head10. The liquid container2, the pump31, and the heater32may be mounted on, for example, the carriage5. The liquid container2, the pump31, and the heater32are coupled to the supply flow path35.

The ink flows through the supply flow path35, passes through the ink supply port18, and is introduced into the flow path inside the flow path structure13. The flow path inside the flow path structure13is branched into a plurality of portions and is coupled to the plurality of head chips11. The head chip11is provided with the common liquid chamber34. The ink introduced into the head chip11is stored in the common liquid chamber34. A part of the ink stored in the common liquid chamber34is ejected from the nozzles N.

The filter33is provided upstream of the common liquid chamber34in the flow path inside the flow path structure13. The ink that has passed through the filter33is supplied to the common liquid chamber34. The filter33removes foreign matter and air bubbles mixed in the ink.

The ink that is not ejected from the nozzles N in the ink stored in the common liquid chamber34is collected in the liquid container2. The ink discharged from the common liquid chamber34flows through the flow path inside the flow path structure13, passes through the ink discharge port19, and is discharged outside the flow path structure13. The ink discharged from the ink discharge port19flows through the collection flow path36and is collected in the liquid container2. As described above, the ink is circulated.

The head chip11includes the common liquid chamber34, pressure chambers37, piezoelectric actuators38, and the nozzles N. A plurality of pressure chambers37are coupled to the common liquid chamber34. The piezoelectric actuator38and the nozzle N are provided for each of the plurality of pressure chambers37. The pressure chamber37enables the common liquid chamber34and the nozzle N to communicate with each other. The ink in the common liquid chamber34flows into the pressure chamber37.

The piezoelectric actuator38is electrically coupled to the control unit3. The piezoelectric actuator38is controlled and driven by the control unit3. The piezoelectric actuator38deforms wall surfaces of the pressure chamber37to change the volume of the pressure chamber37interior. As a result, the piezoelectric actuator38ejects the ink in the pressure chamber37from the nozzle N. Note that the liquid ejecting head10may be configured to include other driving elements, such as heat generating elements, instead of the piezoelectric actuators38.

The temperature sensor20detects a temperature of the ink flowing through a flow path35binside the flow path structure13. The temperature sensor20detects the ink in the flow path35bdownstream of the ink supply port18. Note that the temperature sensor20may detect a temperature of the ink in the flow path35bdownstream of the filter33. The temperature sensor20may detect a temperature of the ink in a flow path35aupstream of the ink supply port18. In addition, the temperature sensor20may detect a temperature of the ink in flow paths36aand36bdownstream of the common liquid chamber34.

The temperature sensor20is disposed on the upper portion of the flow path structure13as illustrated inFIG.2. The temperature sensor20is disposed on the flow path substrate17disposed on the uppermost side.FIG.5is a plan view illustrating the temperature sensor20and wiring lines21. The temperature sensor20is electrically coupled to the wiring lines21formed on a flexible substrate22. In addition, an electronic component24, such as a capacitor is electrically coupled to the wiring lines21. The flexible substrate22is coupled to the connector15. The temperature sensor20is electrically coupled to the control unit3. The temperature sensor20is electrically coupled to the wiring lines21via coupling terminals23provided on the flexible substrate22.

FIG.6is a sectional view illustrating the temperature sensor20and a protrusion portion80and is a view illustrating a cross section in a flow direction of the ink.FIG.7is a sectional view illustrating the temperature sensor20and the protrusion portion80and is a view illustrating a cross section orthogonal to the flow direction of the ink.FIG.8is a sectional view illustrating the protrusion portion80when viewed in the Z-axis direction. InFIGS.6to8, arrows indicating the flow direction of the ink are illustrated. InFIGS.6to8, the ink flows substantially in the Y1 direction.

As illustrated inFIGS.6and7, the temperature sensor20detects a temperature of the ink in a flow path51of the flow path structure13. The flow path structure13includes the plurality of flow path substrates17as described above. The plurality of flow path substrates17include flow path substrates17A and17B. The flow path substrate17A is laminated on the flow path substrate17B. A thickness direction of the flow path substrates17A and17B corresponds to the Z-axis direction. The flow path substrate17A is disposed in the Z2 direction of the flow path substrate17B. The flow path substrate17A is an example of a first flow path substrate, and the flow path substrate17B is an example of a second flow path substrate. The flow path51is, for example, a part of the supply flow path35b.

The flow path structure13has inner surfaces60that define the flow path51and an outer surface70on a side opposite to the flow path51with respect to the inner surfaces60. The inner surface60is an example of an inner wall surface, and the outer surface70is an example of an outer wall surface. The outer surface70is a surface on an outer side of the flow path structure13that does not constitute the flow path51.

The inner surfaces60include inner surfaces61and62. The inner surfaces61and62are spaced apart from each other in the Z-axis direction. In the Z-axis direction, a region between the inner surfaces61and62constitutes the flow path51. The inner surfaces60include inner surfaces63and63, as illustrated inFIGS.7and8. The inner surfaces63and63are spaced apart from each other in the X-axis direction. In the X-axis direction, a region between the inner surfaces63and63constitutes the flow path51. The inner surfaces61and63are formed on the flow path substrate17A. The inner surface62is formed on the flow path substrate17B. The flow path substrate17is made of, for example, a resin.

As illustrated inFIG.6, an opening52passing through the flow path substrate17A in the Z-axis direction is formed in the flow path substrate17A. The opening52communicates with the flow path51. The opening52is formed upward from the flow path51. The flow path structure13includes a sealing portion50that covers the opening52. The sealing portion50includes the above-mentioned flexible substrate22and sealing plates53and54. A thickness direction of the flexible substrate22and the sealing plates53and54corresponds to the Z-axis direction.

The sealing plate53is disposed at a position closest to the opening52in the Z-axis direction. The sealing plate53covers the opening52from above. The sealing plate54is disposed in the Z2 direction of the sealing plate53. The flexible substrate22is disposed in the Z2 direction of the sealing plate54. The sealing plate54functions as a reinforcing plate reinforcing the flexible substrate22.

A metal or a ceramic can be used as a material for the sealing plates53and54. It is preferable to use a metal or a ceramic having high thermal conductivity as the material for the sealing plates53and54. As the metal, for example, stainless steel or aluminum can be used. The number of sealing plates53and54included in the sealing portion50is not limited to two, and may be one or may be three or more. The sealing portion50is not limited to including the flexible substrate22. The flexible substrate22and the sealing plates53and54may be adhered to each other by, for example, an adhesive having high thermal conductivity.

The sealing portion50includes an inner surface50aand an outer surface50bspaced apart from each other in the Z-axis direction. The inner surface50ais a surface, in the Z1 direction, of the sealing plate53positioned on the most Z1 direction side in the sealing portion50. The inner surface50ais included in the inner surface60that defines the flow path51. The outer surface50bis a surface, in the Z2 direction, of the flexible substrate22positioned on the most Z2 direction side in the sealing portion50. The outer surface50bis included in the outer surface70. The temperature sensor20is installed on the outer surface50bof the sealing portion50. The temperature sensor20may be adhered to the sealing portion50by, for example, an adhesive having high thermal conductivity. When the sealing portion50does not include the flexible substrate22, the temperature sensor20may be installed on the sealing plate54. In this case, the temperature sensor20is electrically coupled to the flexible substrate22existing in the vicinity of the temperature sensor20.

The flow path structure13includes the protrusion portion80protruding into the flow path51from the inner surface62toward the temperature sensor20. The protrusion portion80is positioned in the Z1 direction of the opening52. The protrusion portion80includes a slope81, a top surface82, and a slope83. The slope81is an example of a first slope. The slope81includes a surface disposed upstream of the temperature sensor20in the Y-axis direction. Most of the slope81is disposed upstream of the temperature sensor20. A part of the slope81may be disposed so as to overlap the temperature sensor20when viewed in the Z-axis direction.

The slope81is inclined with respect to the inner surface62when viewed in the X-axis direction. An inclination angle θ of the slope81with respect to the inner surface62is, for example, 45°. The inclination angle θ of the slope81may be, for example, 50° or less. The inner surface62is an example of a reference plane, and is a surface along the X-axis direction and the Y-axis direction.

A position P1of the slope81is the most upstream position of the slope81. A position P2of the slope81is the most downstream position of the slope81. The position P2is located at a position closer to the temperature sensor20than the position P1is, in the Z-axis direction. The position P1is an example of a first position of the first slope. The position P2is an example of a second position of the first slope. The slope81is inclined so that the position P2on the downstream is closer to the temperature sensor20in the Z-axis direction than the position P1on the upstream is.

The top surface82is a surface in the Y-axis direction when viewed in the X-axis direction. The top surface82is disposed downstream of the slope81. In the protrusion portion80, the top surface82is a surface closest to the temperature sensor20. The top surface82may be linearly formed or may be curved when viewed in the X-axis direction. The top surface82is disposed so as to overlap the temperature sensor20when viewed in the Z-axis direction.

The slope83is disposed downstream of the top surface82. The slope83includes a surface disposed downstream of the temperature sensor20in the Y-axis direction. Most of the slope83is disposed downstream of the temperature sensor20. A part of the slope83may be disposed so as to overlap the temperature sensor20when viewed in the Z-axis direction. The slope83is inclined with respect to the inner surface62when viewed in the X-axis direction. An inclination angle of the slope83with respect to the inner surface62is, for example, 45°. The inclination angle of the slope83with respect to the inner surface62may be 50° or less. The slope83may have the same inclination angle as the slope81or may have an inclination angle different from that of the slope81.

A position P3of the slope83is the most upstream position of the slope83. A position P4of the slope83is the most downstream position of the slope83. The position P3is located at a position closer to the temperature sensor20than the position P4is, in the Z-axis direction. The slope83is inclined so that the position P4on the downstream is further from the temperature sensor20in the Z-axis direction than the position P3on the upstream is.

The flow path51includes a narrowed region55having a narrow width in the Z-axis direction. The narrowed region55includes a region between the top surface82of the protrusion portion80and the inner surface50aof the sealing portion50in the Z-axis direction. A width W1of the narrowed region55is smaller than a width W2of the flow path51. The width W1is a distance between the top surface82and the inner surface50ain the Z-axis direction. The width W2is a distance between the inner surface61and the inner surface62in the Z-axis direction.

The temperature sensor20is disposed on a portion forming the narrowed region55. The portion forming the narrowed region55includes a portion of the outer surface70that overlaps the narrowed region55when viewed in the Z-axis direction intersecting the flow direction of the ink. The portion forming the narrowed region55includes a position of the outer surface50bof the sealing portion50that overlaps with the top surface82when viewed in the Z-axis direction. The “flow direction of the ink” mentioned here is the Y-axis direction, and is a direction along the top surface82when viewed in the X-axis direction. In addition, the flow direction of the ink may be a direction orthogonal to a lamination direction of the flow path substrates17. In addition, the “flow direction of the ink” may be a direction in which the flow path51which is a flow path detected by the temperature sensor20and includes the narrowed region55extends, when viewed in the Z-axis direction in a direction in which the temperature sensor20is laminated with respect to the outer surface70.

A height H1of the protrusion portion80corresponds to, for example, a length equal to 50% of the width W2of the flow path51. The height H1of the protrusion portion80is a distance between the inner surface62and the top surface82in the Z-axis direction. The height H1of the protrusion portion80may be 30% or more and less than 70% of the width W2of the flow path51. The height H1of the protrusion portion80may be 45% or more and 55% or less of the width W2of the flow path51. In addition, the width W1may be 50% or more and less than 95% of the width W2.

A virtual plane F1extending along the slope81overlaps the temperature sensor20when viewed in the X-axis direction. An inclination angle of the virtual plane F1with respect to the inner surface62is the same inclination angle θ as the slope81.

The flow path substrate17A includes a slope56disposed upstream of the temperature sensor20in the Y-axis direction and a slope57disposed downstream of the temperature sensor20in the Y-axis direction. The slope56is an example of a second slope. The slope56is spaced apart from the slope81in a normal direction U1of the slope81.

A position P5of the slope56is the most upstream position of the slope56. A position P6of the slope56is the most downstream position of the slope56. The position P6is disposed at a position closer to the temperature sensor20than the position P5is, in the Z-axis direction. The position P5is an example of a first position of the second slope. The position P6is an example of a second position of the second slope. The slope56is inclined so that the position P6on the downstream is closer to the temperature sensor20in the Z-axis direction than the position P5on the upstream is.

A position P7of the slope57is the most upstream position of the slope57. A position P8of the slope57is the most downstream position of the slope57. The position P7is disposed at a position closer to the temperature sensor20than the position P8is, in the Z-axis direction. The slope57is inclined so that the position P8on the downstream is further from the temperature sensor20in the Z-axis direction than the position P7on the upstream is.

The slope56is disposed in the Y2 direction of the opening52, and the slope57is disposed in the Y1 direction of the opening52. The opening52is long in the Y-axis direction. A length W3of the opening52in the Y-axis direction is greater than a length W4of the opening52in the X-axis direction. The phrase “long in the Y-axis direction” means that the length W3in the Y-axis direction is longer than the length W4in the X-axis direction. The length W3is a length between the position P6and the position P7in the Y-axis direction. The length W4is a length between an inner surface52aand an inner surface52bin the X-axis direction. The inner surface52aand the inner surface52bare surfaces that define the opening52, are spaced apart from each other in the X-axis direction, and are extend in the Y-axis direction and the Z-axis direction.

The length W3of the opening52in the Y-axis direction is greater than a length W5of the protrusion portion80in the Y-axis direction. The length W5is a length between the position P1and the position P4in the Y-axis direction.

As illustrated inFIGS.7and8, the flow path51is also formed on both sides of the protrusion portion80in the X-axis direction. The protrusion portion80has side surfaces84and84that are spaced apart in the X-axis direction. The side surfaces84face the inner surfaces63in the X-axis direction. Regions between the inner surfaces63and the side surfaces84are also included in the flow path51.

As illustrated inFIG.7, in a cross section orthogonal to the Y-axis direction, a cross-sectional area S1of the flow path close to the temperature sensor20from the top surface82is greater than the sum of cross-sectional areas S2and S3of the flow path51far from the temperature sensor20from the top surface82. InFIG.7, a cross section, orthogonal to a Y axis, of the flow path51cut so as to pass through the temperature sensor20and the top surface82is illustrated. InFIG.7, a virtual line L1extending in the X-axis direction along the top surface82is illustrated by a two-dot chain line. The cross-sectional area S1is a region located in the Z2 direction with respect to the virtual line L1in a cross section of the flow path51. The cross-sectional area S2is a region positioned in the Z1 direction with respect to the virtual line L1in the cross section of the flow path51, and is a region positioned in the X1 direction of the protrusion portion80. The cross-sectional area S3is a region positioned in the Z1 direction with respect to the virtual line L1in the cross section of the flow path51, and is a region positioned in the X2 direction of the protrusion portion80. The cross-sectional area S1is greater than the sum of the cross-sectional areas S2and S3.

In addition, a width W6of the protrusion portion80in the X-axis direction is greater than a width W7of the temperature sensor20in the X-axis direction. The width W6of the protrusion portion80in the X-axis direction is smaller than a width W8of the flow path51in the X-axis direction. The width W8of the flow path51in the X-axis direction is a length between the inner surfaces63and63in the X-axis direction. The width W6of the protrusion portion80formed on the flow path substrate17B is narrower than a distance between the inner surfaces63and63formed on the flow path substrate17A. As a result, a defect that the protrusion portion80cannot be disposed between the inner surfaces63and63when the flow path substrates17A and17B are laminated is prevented.

In such a liquid ejecting apparatus1, the temperature of the ink flowing in the flow path51is detected by the temperature sensor20disposed on the outer surface50bof the sealing portion50. Information on the temperature of the ink detected by the temperature sensor20is input to the control unit3. The control unit3may calculate the ink viscosity based on the temperature of the ink flowing in the flow path51. The control unit3can control the piezoelectric actuator38according to the ink viscosity to adjust an ejection amount of the ink, or control the heater32to adjust the temperature of the ink supplied to the liquid ejecting head10.

According to the liquid ejecting apparatus1, since the protrusion portion80protruding from the inner surface62toward the temperature sensor20in the Z2 direction is provided, a flow of the ink flowing in the flow path51can be brought to the temperature sensor20in the Z-axis direction. The temperature of the ink flowing inside the flow path51is higher in a portion close to the center than a portion far from the center, in the cross section orthogonal to the flow direction of the ink. In the liquid ejecting apparatus1, since a flow near the center can be brought closer to the temperature sensor20in the cross section of the flow path51, detection accuracy of the temperature of the ink by the temperature sensor20can be improved.

In the liquid ejecting apparatus1, since the slope81is provided upstream of the protrusion portion80, it is easy to bring the flow of the ink toward the temperature sensor20while suppressing an increase in pressure loss of the ink. In addition, in the liquid ejecting apparatus1, since the slope83is provided downstream of the protrusion portion80, the flow of the ink can be returned from the temperature sensor20toward the Z1 direction while suppressing an increase in pressure loss of the ink.

In the liquid ejecting apparatus1, the opening52is formed in the Z2 direction of the protrusion portion80, and the opening52is long in the Y-axis direction. It is easy to bring the flow of the ink toward the temperature sensor20when the length of the opening52in the Y-axis direction is great as compared to the case when the length the opening52in the Y-axis direction is small. When the length of the opening52in the Y-axis direction is small, the flow of the ink in the Y-axis direction at a position close to the temperature sensor20becomes short, such that it is difficult to bring the flow of the ink close to the temperature sensor20. When the length W3of the opening52in the Y-axis direction is great, the flow of the ink in contact with the inner surface50aof the sealing portion50can be lengthened. As a result, the flow of the ink can be brought closer to the temperature sensor20, such that detection accuracy of the temperature of the ink by the temperature sensor20can be improved.

In the liquid ejecting apparatus1, when viewed in the X-axis direction, the virtual plane F1extending along the slope81of the protrusion portion80overlaps the temperature sensor20. Since such a slope81is provided, the ink flowing along the slope81is brought to a position close to the temperature sensor20. For that reason, the detection accuracy of the temperature of the ink by the temperature sensor20can be improved.

In the liquid ejecting apparatus1, the inclination angle θ of the slope81with respect to the inner surface62is 45°. As a result, the flow of the ink can be brought closer to the temperature sensor20while suppressing pressure loss upstream of the protrusion portion80.

In the liquid ejecting apparatus1, the slope56disposed upstream of the temperature sensor20in the Y-axis direction and spaced apart from the slope81in the normal direction U1of the slope81is formed. As a result, the ink flows along the slope56, and thus, it is easy to bring the ink to a position closer to the temperature sensor20while suppressing pressure loss upstream of the temperature sensor20. For that reason, the detection accuracy of the temperature of the ink by the temperature sensor20can be improved.

In the liquid ejecting apparatus1, the temperature sensor20is installed on the outer surface50bof the sealing portion50that seals the opening52. A total thickness of the sealing portion50including the flexible substrate22and the sealing plates53and54laminated in the Z-axis direction is smaller than that of the flow path substrate17A. By installing the temperature sensor20on such a thin sealing portion50, it is possible to allow the temperature sensor20to approach the ink in the flow path51.

When the opening52is provided in the Z-axis direction intersecting the Y-axis direction in which the flow path51extends, there is a risk that stagnation will occur in the flow of the ink. When the stagnation occurs in the opening52, there is a risk of the decreased accuracy of the temperature of the ink detected by the temperature sensor20. However, in the liquid ejecting apparatus1, since the protrusion portion80is provided in the Z1 direction of the opening52, the flow of the ink can be brought to a position closer to the opening52. Therefore, the flow of the ink in the opening52can be increased, such that the stagnation of the flow of the ink in the opening52can be suppressed. As a result, the detection accuracy of the temperature of the ink by the temperature sensor20can be improved.

In the liquid ejecting apparatus1, since the flow path substrate17is made of the resin, a manufacturing cost of the flow path structure13can be reduced and a weight of the liquid ejecting head10can be reduced. When the flow path substrate17is made of the resin, a thickness of the flow path substrate17becomes great, but by providing the opening52in the flow path substrate17and sealing the opening52with the sealing portion50having a small thickness, thermal resistance from the flow path51to the temperature sensor20can be decreased. Further, by including the sealing plates53and54made of the metal or the ceramic in at least a part of the sealing portion50, the thermal resistance from the flow path51to the temperature sensor20can be further decreased.

In the liquid ejecting apparatus1, the length W3of the opening52in the Y-axis direction is greater than the length W5of the protrusion portion80in the Y-axis direction. As a result, it is easy to bring the ink into the opening52while suppressing an increase in resistance in the flow path51in the vicinity of the protrusion portion80.

In the liquid ejecting apparatus1, the protrusion portion80is formed on a side opposite to the opening52in the Z-axis direction. When the opening52is positioned at an upper portion, it is easy for air bubbles to stay, but since the protrusion portion80is formed below the opening52, the flow of the ink flowing into the opening52is increased, such that the staying of the air bubbles in the opening52can be suppressed. Since the air bubbles flow due to the flow of the ink flowing into the opening52, the staying of the air bubbles in the opening52is suppressed.

In the liquid ejecting apparatus1, in the cross section orthogonal to the Y-axis direction, the cross-sectional area S1of the flow path51close to the temperature sensor20from the top surface82is greater than the cross-sectional areas S2and S3of the flow path51far from the temperature sensor20from the top surface82. As a result, resistance of the flow path closer to the temperature sensor20can be made smaller than resistance of the flow path further from the temperature sensor20. For that reason, it is easy for the ink to flow to a side closer to the temperature sensor20, such that a flow rate of the ink flowing near the temperature sensor20can be increased. As a result, it is possible to suppress the staying of the air bubbles in the opening52and improve the detection accuracy of the temperature of the ink by the temperature sensor20.

FIG.9is a perspective view illustrating an example of the flow path51formed inside the flow path structure13. InFIG.9, shapes of the flow paths35b,36b, and51formed inside the flow path structure13are illustrated. The flow path structure13includes the plurality of flow path substrates17. InFIG.9, the flow path structure13and the flow path substrates17are not illustrated. The flow paths35b,36b, and51are formed by grooves, through holes, faces in contact with these grooves and through holes, or the like, provided in the flow path substrates17. The flow paths35bare supply flow paths35bin the flow path structure13and allow the ink supply ports18and the common liquid chambers34to communicate with each other. The flow paths36bare collection flow paths36bin the flow path structure13, and allow the common liquid chambers34and the ink discharge ports19to communicate with each other. The flow path51is a flow path in the vicinity of the temperature sensor20, and is included in, for example, the supply flow path35b. The supply flow paths35bare provided with the filters33.

The temperature sensor20is disposed on the opening52that communicates with the flow path51. Note that inFIG.9, the sealing portion50that seals the opening52is not illustrated. The protrusion portion80is formed below the opening52, as described above. In the liquid ejecting apparatus1, the temperature sensor20can be installed with respect to such a flow path51to detect the temperature of the ink flowing in the flow path51.

InFIG.9, the flow paths35band36bare provided for each type of ink. Only one temperature sensor20may be provided in the flow path structure13or a plurality of temperature sensors20may be provided in the flow path structure13according to the type of ink.

Next, a disposition of a temperature sensor20of a liquid ejecting head10B according to a second embodiment will be described with reference toFIG.10.FIG.10is a sectional view illustrating the temperature sensor20and a narrowed region55B of the liquid ejecting head10B according to the second embodiment. In the liquid ejecting head10B, an installation surface of the temperature sensor20is disposed below an inner surface61that defines a flow path51B, in the Z-axis direction.

A recess portion25recessed toward the inside of the flow path51B in the Z1 direction is formed on an outer wall surface of a flow path substrate17A of the liquid ejecting head10B. The recess portion25is recessed in the flow path51B in the Z1 direction. An opening52communicating with the flow path51B is formed at a bottom portion of the recess portion25. The opening52is covered with a sealing portion50.

An inner surface50aand an outer surface50bof the sealing portion50are disposed in the Z1 direction with respect to the inner surface61in the Z-axis direction. The outer surface50b, which is an installation surface on which the temperature sensor20is disposed, is disposed at a position close to the top surface82of the protrusion portion80in the Z-axis direction.

The liquid ejecting head10B according to the second embodiment as described above also has an action effect similar to that of the liquid ejecting head10according to the first embodiment. In the liquid ejecting head10B, the recess portion25is formed and the temperature sensor20is disposed at a position close to the protrusion portion80, and thus, the temperature sensor20is disposed at a position close to the center of a flow of an ink in a cross section of the flow path51B. For that reason, the detection accuracy of the temperature of the ink by the temperature sensor20can be improved. Note that in the present embodiment, the protrusion portion80protruding from the inner surface62may not be provided.

Next, a liquid ejecting apparatus1B according to a third embodiment will be described with reference toFIG.11.FIG.11is a schematic view illustrating a configuration of the liquid ejecting apparatus1B according to the third embodiment. The liquid ejecting apparatus1B is a line head type printing apparatus. The liquid ejecting apparatus1B includes a plurality of liquid ejecting heads10B. The plurality of liquid ejecting heads10B are arranged in a predetermined direction to constitute a line head90. The plurality of liquid ejecting heads10B are arranged in, for example, a width direction of the medium PA.

An ink stored in a liquid container2is supplied to the liquid ejecting head10B via a circulation mechanism7. The circulation mechanism7supplies the ink to the liquid ejecting head10B and collects the ink discharged from the liquid ejecting head10B. The circulation mechanism7supplies the collected ink to the liquid ejecting head10B again. The circulation mechanism7includes a flow path for supplying the ink to the liquid ejecting head10B, a flow path for collecting the ink discharged from the liquid ejecting head10, a sub-tank for storing the collected ink, a pump for transferring the ink, and the like.

The liquid ejecting head10B includes a flow path structure in which a flow path through which the ink flows is formed, similar to the liquid ejecting head10according to the first embodiment described above. The flow path structure includes a plurality of flow path substrates, and the flow paths are formed by grooves, holes, surfaces, and the like, formed in the flow path substrates. The liquid ejecting head10B includes a temperature sensor20that detects a temperature of the ink in the flow path. A protrusion portion protruding into the flow path is formed on the flow path substrate. The temperature sensor20is disposed at a position facing the protrusion portion with the flow path interposed therebetween.

The liquid ejecting apparatus1B according to the third embodiment as described above also has an action effect similar to that of the liquid ejecting apparatus1described above. A configuration of the liquid ejecting head10B may be the same as that of the liquid ejecting head10or may be different from that of the liquid ejecting head10.

Next, a liquid ejecting head10according to a first modification will be described. The liquid ejecting head10according to the first modification is different from the liquid ejecting heads10according to the above-described embodiments in that the opening52is provided upstream of the filter33and the temperature sensor20is installed at a position corresponding to the opening52. The opening52is covered with the sealing portion50as in the above-described embodiments, and the temperature sensor20is installed on the outer surface50bof the sealing portion50.

The liquid ejecting head10according to the first modification as described above also has an action effect similar to that of the liquid ejecting head10described above. In the liquid ejecting head10according to the first modification, since the temperature sensor20is installed with respect to the flow path downstream of the filter33, the temperature sensor20can detect the temperature of the ink at a position closer to the nozzle N. In other words, the temperature sensor20can detect the temperature of the ink at a position close to the piezoelectric actuator38. In addition, a configuration in which it is difficult for the air bubbles to stay in the opening52provided in a direction opposite to the direction of gravity with respect to the flow path51is realized by the protrusion portion80. As a result, influence of the air bubbles staying and growing in the opening52downstream of the filter33on discharge from the nozzle N can be suppressed and the piezoelectric actuator38can be controlled according to the temperature of the ink at a position close to the piezoelectric actuator38, such that high-precision printing can be realized.

Next, a liquid ejecting head10according to a second modification will be described. The liquid ejecting head10according to the second modification is different from the liquid ejecting heads10according to the above-described embodiments in that the temperature sensor20is provided at an inlet port of the flow path structure13. The inlet port is, for example, the ink supply port18. The inlet port of the flow path structure13is, for example, a tubular body, and a tube is coupled to this inlet port. An ink flowing in the tube passes through the inlet port and flows into the flow path inside the flow path structure13.

In the second modification, the temperature sensor20is installed on an outer surface of the tubular body constituting the inlet port. Also in the liquid ejecting head10according to the second modification as described above, a protrusion portion that protrudes into the flow path toward the temperature sensor20is provided. The liquid ejecting head10according to the second modification as described above also has an action effect similar to that of the liquid ejecting apparatus1described above.

Note that the above-described embodiments merely show typical embodiments of the present disclosure, the present disclosure is not limited to the above-described embodiments, and various modifications and additions can be made without departing from the gist of the present disclosure.

In the above-described embodiment, the narrowed region55in which a width of the flow path is small in the Z-axis direction has been described by way of example, but a direction in which the width of the flow path is small is not limited to the Z-axis direction, and the narrowed region55may be a narrowed region having a narrow width in another direction intersecting the flow direction of the ink. The flow direction of the ink in the vicinity of the temperature sensor20is not limited to the Y-axis direction, and may be the Z-axis direction or the X-axis direction. For example, when the flow direction of the ink is the Z-axis direction, the protrusion portion may be provided in the X1 direction of the flow path, and the temperature sensor20may be disposed in the X2 direction of the flow path.

In the above-described embodiment, a case where the temperature sensor20is disposed in the Z2 direction with respect to the flow path51has been described by way of example, but a direction in which the temperature sensor20is disposed is not limited to the Z2 direction, and may be the Z1 direction, the X1 direction, the X2 direction, or any other direction. Similarly, a direction in which the protrusion portion80protrudes is not limited to the Z2 direction, and the protrusion portion80may protrude in any other direction. The protrusion portion80is only required to be able to bring the flow of the ink to a position close to the temperature sensor20.

In addition, in the above-described embodiment, the opening52has been covered from the outside of the flow path using the sealing plate53, but the sealing plate may be disposed so as to cover the opening52from the inside of the flow path. In addition, the opening communicating with the flow path may not be formed. For example, a thickness of a portion of the flow path substrate17in contact with the flow path may be reduced, and the temperature sensor20may be installed in this portion.

In addition, in the above embodiment, as illustrated inFIGS.6and7, the flow path51has been formed by the flow path substrates17A and17B, but the flow path51may be formed by one flow path substrate17or may be formed by three or more flow path substrates17. For example, a third flow path substrate17may be disposed between the flow path substrate17A and the flow path substrate17B. The flow path51may be formed by the inner surface61of the flow path substrate17A, an opening formed in the third flow path substrate17and passing through the third flow path substrate17in a plate thickness direction, and the inner surface62of the flow path substrate17B. In addition, the flow path51may be configured by an inner surface61of the flow path substrate17A and a groove of the flow path substrate17B.

In addition, the temperature sensor20may be installed on an outer surface of a pipe through which the ink flows or a sealing portion may be provided at a portion coupling the pipes to each other and the temperature sensor20may be installed on an outer surface of the sealing portion.

The liquid ejecting apparatus described by way of example in the above-described embodiments can be adopted in various apparatuses such as a facsimile apparatus or a copying machine, in addition to an apparatus dedicated to printing. However, a use of the liquid ejecting apparatus is not limited to the printing. For example, a liquid ejecting apparatus that discharges a solution of a coloring material is used as a manufacturing apparatus that forms a color filter of a display apparatus such as a liquid crystal display panel. In addition, a liquid ejecting apparatus that discharges a solution of a conductive material is used as a manufacturing apparatus that forms a wiring line or an electrode of a wiring board. In addition, a liquid ejecting apparatus that discharges a solution of an organic matter relating to a living body is used as a manufacturing apparatus that manufactures, for example, a biochip.