JP2010214924A - Liquid ejection device - Google Patents

Abstract

A liquid ejection apparatus capable of easily stabilizing the liquid ejection characteristics with respect to an environmental temperature is provided.
An ink tank that stores ink, an ink supply pipe that communicates with the ink tank and supplies ink in the ink tank, and a recording head that discharges ink supplied from the ink supply pipe from a nozzle opening. A circulation channel 55 that covers the ink ejection unit with the nozzle openings exposed to the outside, and the circulation channel 55 is filled with water 56. Circulating water adjusts the temperature of the ink in the ink discharge unit.
[Selection] Figure 3

Description

  The present invention relates to a liquid ejection apparatus that ejects liquid from a nozzle opening of a liquid ejection head such as an ink jet recording head.

  The liquid ejection apparatus is an apparatus that includes a liquid ejection head capable of ejecting liquid and ejects various liquids from the liquid ejection head. As a typical example of this liquid ejection apparatus, for example, an ink jet recording head (hereinafter simply referred to as a recording head) as a liquid ejection head is provided, and liquid ink is recorded on recording paper or the like from a nozzle opening of the recording head. An image recording apparatus such as an ink jet printer that records an image or the like by ejecting and landing on a medium (ejection target) to form dots can be exemplified. In recent years, liquid ejecting apparatuses have been applied not only to the image recording apparatus but also to various manufacturing apparatuses such as a manufacturing apparatus for a color filter such as a liquid crystal display.

  By the way, in the printer described above, there are cases where the ejection characteristics such as the amount of ink ejected from the nozzle opening and the flying speed fluctuate due to the change in the ink viscosity caused by the change in the environmental temperature. Therefore, a configuration has been proposed in which an ink heater and a temperature sensor are provided for each head unit, and the ink heater of each head unit is controlled to a preset temperature based on the temperature detected by the temperature sensor (for example, Patent Document 1). In addition, a configuration has been proposed in which a liquid channel that circulates a liquid (heat medium) for heating ink in the recording head is disposed adjacent to the ink channel in the recording head (for example, Patent Document 2). reference).

JP 2007-223144 A JP 2008-055716 A

  However, in the configuration including the ink heater and the temperature sensor for each head unit of Patent Document 1, the structure and control are complicated, and the liquid ejection characteristics cannot be easily stabilized. Further, in the configuration in which the temperature of the ink supplied into the recording head of Patent Document 2 is controlled by the liquid flow path, the ink flow in the recording head is transferred in order to transfer the heat of the liquid in the liquid flow path to the ink. It is necessary to make the path and the liquid flow path adjacent to each other. However, since the arrangement of the ink flow path and the liquid flow path in the recording head is limited, the temperature range of heat transfer becomes narrow and the temperature varies. There was an inconvenience. As a result, the range in which the ink temperature can be controlled is limited, and it has not been possible to sufficiently stabilize the ink ejection characteristics against changes in the environmental temperature.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a liquid ejection apparatus capable of easily stabilizing the liquid ejection characteristics with respect to the environmental temperature.

The present invention has been proposed in order to achieve the above object, and a liquid storage section for storing a liquid;
A liquid supply path that communicates with the liquid reservoir and supplies the liquid in the liquid reservoir;
A liquid discharge head for discharging the liquid supplied from the liquid supply path from a nozzle opening;
A liquid discharge apparatus comprising a liquid discharge unit having
A circulation channel that covers the liquid discharge unit is formed with the nozzle opening exposed to the outside, a heat medium is filled in the circulation channel, and the heat medium is circulated to circulate the liquid in the liquid discharge unit. It is characterized by adjusting the temperature.

  According to this configuration, the liquid discharge unit is formed by forming the circulation flow path that covers the liquid discharge unit with the nozzle opening exposed to the outside, filling the heat transfer medium in the circulation flow path, and circulating the heat medium. Since the temperature of the liquid inside is adjusted, the temperature of the liquid can be adjusted to be constant in a series of flow paths extending from the liquid reservoir to the liquid ejection head. For this reason, the liquid in a liquid discharge unit can be adjusted to the viscosity suitable for discharge. As a result, the ejection characteristics such as the amount of liquid ejected from the nozzle opening and the flying speed can be easily stabilized.

In the above configuration, a temperature detection unit that detects the temperature of the liquid in the liquid discharge head;
A heat exchange unit that adjusts the temperature of the heat medium based on the temperature detected by the temperature detection unit;
A circulation driving unit for circulating the temperature-controlled heat medium in the circulation channel;
It is possible to employ a configuration comprising:

  According to this configuration, the heat medium circulation mechanism includes a temperature detection unit that detects the temperature of the liquid in the liquid discharge head, a heat exchange unit that adjusts the temperature of the heat medium based on the temperature detected by the temperature detection unit, And a circulation drive unit that circulates the temperature-controlled heat medium in the circulation flow path, so that the temperature of the liquid in the liquid discharge unit can be adjusted with high accuracy. Thereby, the ejection characteristics such as the amount of liquid ejected from the nozzle opening and the flight speed can be further stabilized.

  The said structure WHEREIN: The structure formed through the flexible film body which separates the said liquid discharge unit and the said heat medium can be employ | adopted.

  According to this configuration, the circulation flow path is formed through the flexible film body that separates the liquid discharge unit and the heat medium, so that the heat medium is brought into contact with the liquid discharge unit through the flexible film body. And a short circuit of the liquid jet unit due to the heat medium can be prevented.

In the above configuration, a housing for housing the liquid discharge unit is provided,
It is possible to employ a configuration in which the circulation flow path is disposed in at least a part of the housing.

  According to this configuration, the housing for housing the liquid discharge unit is provided, and the circulation flow path is disposed in at least a part of the housing. Therefore, the volume of the circulation flow path in the housing is set according to the heat capacity of the liquid discharge unit. By setting, it is possible to reduce the amount of the heat medium filled in the circulation channel while maintaining the heat transfer efficiency.

The said structure WHEREIN: The structure on the opposite side to the liquid discharge unit of the said flexible film body can employ | adopt the structure which is a porous structure.
Moreover, the structure which makes a porous structure can be employ | adopted by filling the bead-shaped microparticle in the said flexible membrane body. Furthermore, the structure which makes a porous structure can be employ | adopted by filling the gel agent in the said flexible membrane body.

  According to the above configuration, since the opposite side of the flexible film body to the liquid discharge unit has a porous structure, the amount of the heat medium to be filled can be reduced. Further, the heat medium can be spread to every corner of the film, and the heat retention efficiency of the liquid discharge unit with respect to the liquid can be improved.

FIG. 2 is a cross-sectional view illustrating a configuration of a printer. It is a top view explaining the structure of an ink discharge unit. It is sectional drawing explaining the structure of an ink discharge unit. FIG. 3 is a cross-sectional view of a main part of the recording head. FIG. 4 is an enlarged view of a region A in FIG. 3. 2 is a block diagram illustrating an electrical configuration of a printer. FIG. It is sectional drawing explaining the structure of the ink discharge unit in 2nd Embodiment.

  The best mode for carrying out the present invention will be described below with reference to the drawings. In the embodiments described below, various limitations are made as preferred specific examples of the present invention. However, the scope of the present invention is not limited to the following description unless otherwise specified. However, the present invention is not limited to these embodiments. In the present embodiment, an image recording apparatus that is a form of a liquid ejecting apparatus (liquid ejecting apparatus), more specifically, the maximum recording width of recording paper that becomes an ejection target (or recording medium) at equal intervals between nozzle aperture groups. An ink jet printer (hereinafter simply referred to as a printer) equipped with a long liquid discharge head (hereinafter referred to as a recording head) disposed at a length corresponding to the above will be described as an example.

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of a printer 1 according to the present invention, and FIG. 2 is a plan view around an ink discharge unit 3 in the printer 1. The printer 1 according to this embodiment includes a plurality of recording heads 11 (books) in a direction (hereinafter referred to as a second direction Y) orthogonal to a conveyance direction (relative feed direction; hereinafter referred to as a first direction X) of the recording paper 4 by the conveyance unit 7. A paper feed tray for storing an ink ejection unit 3 (a kind of liquid ejection unit of the present invention) and a recording paper 4 (a kind of ejection object) in a stacked state. 5a and a lower sheet feeding cassette 5b provided at the lower part of the apparatus, and a recording sheet 4 fed from these sheet feeding sections 5a and 5b is passed under the ink discharge unit 3 and discharged. A transport unit (paper feed mechanism) 7 that transports to the tray 10 side and a paper discharge tray 10 that holds the recording paper 4 on which recording is performed by the ink discharge unit 3 and is discharged from the transport unit 7 side. Unit 3 is configured to be able to record the entire width in the text or image or the like of the recording area of the recording paper 4 without scanning in the first direction X.

  In addition, a printer controller 65 that performs electrical control of each unit is provided inside the apparatus main body 2. The printer controller 65 has a drive signal generation circuit 73 (see FIG. 6), and outputs the drive signal from the drive signal generation circuit 73 to each recording head 11 through a signal cable.

  The paper feed tray 5a is configured to be movable in the vertical direction. The upper surface of the recording paper bundle (the upper surface of the uppermost recording paper 4) is always in contact with the pickup roller 6 with a constant pressure. The vertical position is controlled. Then, in accordance with the execution timing of the recording operation by the ink ejection unit 3, the recording paper 4 is pulled out from the uppermost part of the recording paper bundle by the pickup roller 6, and separated one by one by the separation roller 12 and the separation pad 13. It is fed to the downstream side. After passing between paper sensors (not shown), the recording paper 4 abuts against the nip portion of the pair of upper and lower registration rollers 14a and 14b. The recording paper 4 from the lower paper feed cassette 5b reaches the nip portion of the registration rollers 14a and 14b after passing through a plurality of intermediate rollers 15. Thereby, the leading edge posture of the recording paper 4 is aligned, and the skew of the recording paper 4 is corrected. Thereafter, the registration rollers 14a and 14b feed the recording paper 4 to the transport unit 7 side by side in a state where the recording paper 4 is nipped at a specified timing, and the recording paper 4 reaches the transport belt 17 of the transport unit 7. The nip state is released at a predetermined timing.

  The transport unit 7 is stretched between a driving roller 18 rotated by a driving force of a driving motor (not shown), a driven roller 19 disposed upstream of the driving roller 18, and the driving roller 18 and the driven roller 19. The endless conveyor belt 17 is configured by a tension roller 20 that applies tension to the conveyor belt 17 and a presser roller 21. The tension roller 20 is disposed between the driving roller 18 and the driven roller 19, abuts against the conveyor belt 17 from the inside, and applies tension to the conveyor belt 17 by an urging force of an urging member such as a spring. . The pressing roller 21 is disposed directly above the driven roller 19 with the conveyance belt 17 interposed therebetween, and presses the recording paper 4 on the conveyance belt toward the conveyance belt 17 so that the adhesion of the recording paper 4 to the conveyance belt 17 is achieved. Increase.

  The drive roller 18 is driven in synchronization with the recording operation of the ink discharge unit 3 to rotate the transport belt 17 so that the recording paper 4 passes below the ink discharge unit 3 and is transported downstream. It is configured. Further, the amount of rotation of the conveyor belt 17 is detected by an encoder. The encoder detection signal is output to the printer controller 65 as an encoder pulse.

  When recording is performed on only one side of the recording paper 4, the recording is performed from the transport unit 7 to the paper discharge tray 10 after the recording on one side is completed. On the other hand, when recording is performed on both sides of the recording paper 4, after the recording on one side is completed, the recording paper 4 is transported to the paper reversing path R <b> 2 by the flapper 22 disposed downstream of the transport unit 7. After the recording paper 4 reaches the U-turn portion T of the paper reversing path, the conveyance direction is changed, and the recording paper 4 is sequentially sent again to the registration rollers 14a and 14b and the conveyance belt 17 to complete the recording on the other side. After that, the paper is discharged from the transport unit 7 to the paper discharge tray 10.

  As shown in FIG. 2, the ink ejection unit 3 is configured to arrange a plurality of recording heads 11 in the second direction Y in a head holder 24. In the present embodiment, the four liquid ejection units 3 a to 3 d are attached to the attachment frame 25 at a fixed arrangement interval in the first direction X with the head longitudinal direction aligned with the second direction Y.

  In the nozzle forming substrate (nozzle forming surface) 46 (see FIG. 4) of each recording head 11, a plurality of nozzle openings 53 (see FIG. 4) for ejecting ink are provided along the second direction Y to form nozzle rows. The plurality of nozzle rows are arranged in the first direction X. One nozzle row includes, for example, 360 nozzle openings opened at a pitch of 360 dpi. Each recording head 11 has a total of two nozzle rows arranged in the first direction X. As described above, the nozzle forming substrate 46 of the recording head 11 in the present embodiment has a shape that is long in the second direction Y in plan view. In the state of being attached to the head holder 24, the long side direction of the nozzle forming substrate 46 in plan view is configured to be parallel to the second direction Y.

  As shown in FIG. 2, in the present embodiment, the first liquid ejection unit 3a and the second liquid ejection unit 3b are paired, and the third liquid ejection unit 3c and the fourth liquid ejection unit 3d. And are paired. The two liquid discharge units 3 forming a pair have an arrangement layout in which the recording heads 11 are alternately arranged in a two-stage zigzag pattern at an arrangement interval such that the nozzle openings are arranged in 360 dpi as a whole when viewed in the second direction Y. ing. The number of recording heads 11 in one liquid discharge unit 3 is determined according to the maximum size of the recording paper 4 that can be handled by the printer 1. The attachment frame 25 is a rectangular frame member, and is formed of metal or the like. Inside the frame of the mounting frame 25 is an empty portion 29 in which each recording head 11 of the liquid ejection unit 3 is arranged.

  FIG. 3 is a cross-sectional view showing the configuration of the ink discharge unit 3. The ink discharge unit 3 communicates with the ink tank 31 (a type of liquid storage unit in the present invention) that stores ink (a type of liquid in the present invention) and supplies the ink in the ink tank 31. An ink supply pipe 32 (a kind of liquid supply path in the present invention) and a recording head 11 that discharges ink supplied from the ink supply pipe 32 from a nozzle opening 53 (see FIG. 4). It is accommodated in the housing 33 in a state of being exposed to the surface. The ink tank 31 is disposed inside the housing 33, and ink stored in the ink tank 31 is recorded in each ink discharge unit 3 through the ink supply pipe 32 by pressurization in the ink tank 31 by an air pump or the like. The head 11 is configured to be supplied (pressure fed). The ink supply pipe 32 is a flexible hollow member made of, for example, a synthetic resin such as silicone, and an ink flow path corresponding to each ink tank 31 is formed inside the ink supply pipe 32. ing.

  FIG. 4 is a cross-sectional view of a main part for explaining the configuration of the recording head 11. The recording head 11 includes a head case 35, a vibrator unit 36 housed in the head case 35, a flow path unit 37 joined to the bottom surface (tip surface) of the head case 35, and the like.

  The head case 35 is a hollow box-like member made of, for example, an epoxy-based resin. A flow path unit 37 is fixed to the front end surface (lower surface) of the head case 35, and the head case 35 is accommodated in an accommodation space 38 formed inside the case. Accommodates a vibrator unit 36 which is a kind of actuator, and a drive substrate 39 is disposed on the upper surface side opposite to the tip surface. Further, a case channel 40 is formed in the head case 35 so as to penetrate the height direction. The case flow path 40 is a flow path for supplying ink from the ink tank 31 side to the common ink chamber 50 via the ink supply pipe 32. An inflow opening 41 projects from the upper surface of the head case 35 as an upstream end of each case channel 40. The ink supply pipe 32 is connected to the inflow opening 41.

  The vibrator unit 36 includes a plurality of piezoelectric vibrators 42 arranged in a comb shape, a flexible cable 43 (wiring member) for supplying a drive signal from the drive board 39 to the piezoelectric vibrators 42, and a piezoelectric element. It is composed of a fixed plate 44 for fixing the vibrator 42. The piezoelectric vibrator 42 is joined to a flexible surface (vibrating plate 48) that partitions a part of the pressure generating chamber 52. The piezoelectric vibrator 42 expands or contracts by application of a drive signal to expand or contract the volume of the pressure generating chamber 52, thereby causing pressure fluctuation in the ink in the pressure generating chamber 52, and controlling the pressure fluctuation. Thus, ink can be ejected from the nozzle opening 53.

  The drive substrate 39 attached to the base end surface (upper surface) of the head case 35 receives a drive signal from the drive signal generation circuit 73 (see FIG. 6) of the printer body, and transmits the drive signal through the flexible cable 43 to the vibrator. This is a substrate that relays a drive signal to be supplied to the piezoelectric vibrator 42 of the unit 36. The drive substrate 39 is connected to a temperature sensor (a kind of temperature detection unit in the present invention), which will be described later, and a temperature detection circuit 75 that outputs temperature detection information corresponding to the detected temperature (thermal electromotive force) of the temperature sensor. (See FIG. 6).

  The flow path unit 37 is formed by laminating a nozzle forming substrate 46 having a nozzle opening 53, a flow path forming substrate 47 that forms an ink flow path, and a diaphragm 48 that seals the opening surface of the flow path forming substrate 47. A unit that is formed by joining and integrating, and forms a series of ink flow paths (liquid flow paths) from the common ink chamber 50 to the nozzle openings 53 through the ink supply ports 51 and the pressure generation chambers 52. It is a member. The pressure generation chamber 52 branched from the common ink chamber 50 is formed for each nozzle opening 53 and is configured such that ink is supplied from the ink supply pipe 32 side via the case flow path 40 and the common ink chamber 50. ing. The flow path unit 37 is joined to the front end surface of the head case 35 in a posture in which the nozzle forming substrate 46 is directed downward (in a direction facing the recording paper). Therefore, the nozzle forming substrate 46 becomes a nozzle forming surface (a kind of nozzle surface) in the recording head 11.

  Furthermore, as shown in FIG. 3, the printer 1 of the present invention includes a heat medium circulation mechanism 54 that keeps the temperature of the ink in the liquid ejection unit 3. The heat medium circulation mechanism 54 forms a circulation channel 55 in a state of covering the ink discharge unit 3 with the nozzle opening 53 exposed to the outside, and water 56 (a kind of heat medium in the present invention) in the circulation channel 55. ) And exchanging heat while circulating the water 56, thereby maintaining the temperature of the ink in the ink discharge unit 3. The heat medium circulation mechanism 54 includes a temperature sensor that detects the temperature of ink in the ink discharge unit 54, and a heat exchanger 58 that adjusts the temperature of the water 56 based on the temperature detected by the temperature sensor (heat exchange in the present invention). 1), a pump 59 that circulates the temperature-adjusted water 56 in the circulation channel 55 (a kind of circulation drive unit in the present invention), and a controller 71 that controls the heat exchanger 58 and the pump 59 (FIG. 6). Reference). The heat medium in the present invention is not limited to the water 56, and may be a liquid such as oil or alcohol. That is, the heat medium of the present invention may be a fluid that is antifreeze at a normal use environment temperature and has a high specific heat.

  The circulation channel 55 includes an external circulation channel 55 a disposed outside the housing 33 and an internal circulation channel 55 b connected to the external circulation channel 55 a and disposed inside the housing 33. The external circulation channel 55a is formed in an annular shape that allows an opening serving as an inlet and an outlet of water to communicate with the internal circulation channel 55b, and a heat exchanger 58 and a pump 59 are disposed in the middle thereof.

FIG. 5 is an enlarged view of a region A in FIG. The internal circulation flow path 55b is accommodated (filled) in a film 61 that is a space on the opposite side across the film 61 via a film 61 that separates the ink discharge unit 3 (the recording head 11 in the drawing) and the water 56. It is formed as a gap between the beads 62 (a kind of fine particles in the present invention). The internal circulation channel 55 b in the present embodiment is provided over the entire area of the housing 33 in a state in which the internal circulation channel 55 b is in contact with the ink discharge unit 3 through the film 61. The film 61 is formed in a flexible bag-like shape, and the water 56 in the film 61 and the ink discharge unit 3 are in close contact with each other with the film 61 interposed between them. . Note that the beads 62 are made of plastic particles having a particle diameter of, for example, about 1 to 3 mm, and a plurality of beads 62 are accommodated in the film 61 so that the film 61 has a porous structure. Accordingly, the gap between the beads 62 in the internal circulation channel 55b functions as a channel through which the water 56 flows.
In the internal circulation channel 55 b of the present invention, a gel agent may be disposed in the film 61. Thus, in the circulation channel configured by arranging the gel in the membrane 61, the inside of the membrane 61 is formed in a finer porous structure than the internal circulation channel 55b configured by arranging the beads 62. Therefore, the area in which the ink discharge unit 3 and the water 56 are brought into contact with each other via the film 61 is widened, and the heat conduction efficiency between the ink in the ink discharge unit 3 and the water 56 is increased.
Furthermore, the internal circulation channel 55b of the present invention is not limited to the configuration in which the beads 62 and the gel agent are arranged in the film 61, and fine particles such as metal and carbon are uniformly dispersed in the fluid as the heat medium, and the thermal characteristics. It may be configured to be filled with a functional fluid to which is added. That is, the diameter of the fine particles forming the porous structure in the present invention can be appropriately selected in consideration of the fluid flow characteristics.

  The temperature sensor is made of, for example, a thermocouple, and is electrically connected to the temperature detection circuit 75. The temperature sensor of the present invention is disposed in the recording head 11 and is provided at a position where it directly or indirectly contacts the ink in the recording head 11. The temperature sensor configured as described above detects the temperature of the ink in the recording head 11 based on the electrical signal from the temperature detection circuit 75. The temperature sensor of the present invention is not limited to the configuration arranged in the recording head 11 and may be arranged in the ink tank 31 or the ink supply pipe 32. That is, the temperature sensor of the present invention only needs to be able to detect the temperature of ink in the ink ejection unit 3. In particular, in the configuration in which the temperature sensor is disposed in the vicinity of the nozzle opening 53 from which ink is ejected, the temperature of the ink in the nozzle opening 53 can be detected, and the temperature of the ink immediately before ejection can be detected.

  The heat exchanger 58 is disposed in the middle of the external circulation channel 55a and has a heat exchange element such as a Peltier element. The heat exchanger 58 is electrically connected to the control unit 71 (FIG. 6), and receives the electric signal from the control unit 71 supplied with the temperature detection signal from the temperature sensor, and detects the ink detected by the temperature sensor. The water 56 is cooled or heated based on the ink temperature in the discharge unit 3. For example, the heat exchanger 58 generates heat between the heat exchange element and the water 56 when the temperature detected by the temperature sensor when the recording head 11 generates heat is higher than a preset value suitable for ink ejection. The water 56 is cooled by exchanging heat between the two, while the water 56 is heated when the temperature detected by the temperature sensor is lower than a preset value suitable for ink ejection. Is set. That is, the heat exchanger 58 adjusts the temperature of the water 56 based on the temperature of the ink in the ink ejection unit 3 detected by the temperature sensor.

  The pump 59 is disposed in the middle of the external circulation flow path 55a similarly to the heat exchanger 58, and is electrically connected to the control unit 71 (FIG. 6). The pump 59 receives an electrical signal from the control unit 71, thereby pumping the water 56 sucked from the outlet of the internal circulation channel 55b to the heat exchanger 58, and the water 56 whose temperature is adjusted by the heat exchanger 58. The ink is returned from the inlet into the internal circulation channel 55 b and the temperature of the ink in the ink discharge unit 3 is adjusted via the film 61.

Next, the electrical configuration of the printer 1 will be described.
FIG. 6 is a block diagram illustrating an electrical configuration of the printer 1. The printer 1 in the present embodiment is schematically configured by a printer controller 65 and a print engine 66. The printer controller 65 stores an external interface (external I / F) 67 for inputting print data from an external device such as a host computer, a RAM 68 for storing various data, and a control program for various controls. ROM 69, nonvolatile storage element 70 such as EEPROM or flash ROM, control unit 71 that performs overall control of each unit according to a control program stored in ROM 69, oscillation circuit 72 that generates a clock signal, A drive signal generation circuit 73 (a type of drive signal generation means) that generates a drive signal to be supplied to each recording head 11 of the ink ejection unit 3, and dot pattern data and drive obtained by developing print data for each dot Internal interface for outputting signals etc. to the recording head 11 (internal / F) and a 74.

  The print engine 66 includes a recording head 11 and a paper feed mechanism (conveyance unit) 7. The print engine 66 includes a temperature detection circuit 75 to which the temperature sensor is connected, a heat exchanger 58, and a pump 59. The temperature detection circuit 75 is configured to A / D convert the detection signal of the temperature sensor and output it to the control unit 71 as temperature detection information.

  Here, in the printer 1, the inside of the recording head 11 is heated by the ejection of ink from the nozzle openings 53 by the piezoelectric vibrator 42, and the temperature of the recording head 11 gradually increases. Along with this, the temperature of the ink in the recording head rises, and the viscosity of the ink changes (decreases). As a result, when no measures are taken, there is a possibility that the ejection characteristics such as the amount of ink ejected from the nozzle openings 53 and the flight speed may fluctuate. Further, there is a possibility that variations in ink ejection characteristics may occur depending on the difference in ink temperature for each nozzle opening 53. For example, when the viscosity of the ink decreases, the amount of ink ejected from the nozzle opening 53 that ejects the ink increases. Alternatively, when the ink temperature is lower than a preset temperature suitable for ejection, the viscosity of the ink increases and the amount of ink ejected from the nozzle opening 53 decreases.

  For this reason, the control unit 71 supplies an electrical signal to the heat exchanger 58 based on the temperature detected by the temperature sensor, that is, the temperature detection information from the temperature detection circuit 75, and the heat exchanger 58 causes the internal circulation flow. Based on the ink temperature in the ink discharge unit 3 detected by the temperature sensor, the temperature of the water 56 in the path 55b is adjusted to a preset temperature suitable for ink discharge. And the control part 71 supplies an electric signal to the pump 59, and circulates the water 56 temperature-controlled by the heat exchanger 58 in the circulation flow paths 55a and 55b. For this reason, the ink discharge unit 3 and the water 56 in the internal circulation flow path 55b come into contact with each other through the film 61, and heat transfer occurs between the ink discharge unit 3 and the water 56 in the internal circulation flow path 55b. Is called. Thereby, the temperature of the ink in the ink discharge unit 3 is adjusted to a value suitable for ink discharge set in advance. As a result, the temperature of the ink can be kept constant in a series of ink flow paths from the ink tank 31 to the nozzle openings 53 of the recording head 11, and by adjusting the viscosity of the ink in the ink ejection unit 3, The ejection characteristics such as the amount of ink ejected from the nozzle openings 53 and the flying speed can be easily stabilized.

Next, another embodiment of the present invention will be described.
FIG. 7 is a cross-sectional view illustrating the configuration of the printer 1 according to the second embodiment. The second embodiment is characterized in that the internal circulation channel 55b is provided in a part of the housing 33 in contact with the ink discharge unit 3. The internal circulation flow path 55b of the second embodiment sets the volume of the internal circulation flow path 55b in the housing 33 according to the heat capacity of the ink discharge unit 3, thereby maintaining the heat transfer efficiency and the internal circulation flow. The amount of water 56 that fills the flow path 55b can be reduced.
Note that the printer 1 of the present invention does not necessarily include the heat exchanger 58 and the pump 59 as long as the water 56 in the circulation channel 55 has a volume that can sufficiently absorb the heat capacity of the ink discharge unit 3. Also good.

  The present invention is not limited to a printer as long as it is a liquid ejection device that can perform ejection control using a plurality of drive signals, and other than various ink jet recording devices such as plotters, facsimile devices, copiers, and recording devices. The present invention can also be applied to a liquid ejecting apparatus such as a display manufacturing apparatus, an electrode manufacturing apparatus, and a chip manufacturing apparatus.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 3 ... Ink discharge unit, 11 ... Recording head, 31 ... Ink tank, 32 ... Ink supply pipe, 33 ... Housing, 53 ... Nozzle opening, 55 ... Circulation flow path, 56 ... Water, 58 ... Heat exchange Vessel 59 ... pump 61 ... membrane 62 ... bead

Claims (7)

A liquid reservoir for storing liquid;
A liquid supply path that communicates with the liquid reservoir and supplies the liquid in the liquid reservoir;
A liquid discharge head for discharging the liquid supplied from the liquid supply path from a nozzle opening;
A liquid discharge apparatus comprising a liquid discharge unit having
A circulation channel that covers the liquid discharge unit is formed with the nozzle opening exposed to the outside, a heat medium is filled in the circulation channel, and the heat medium is circulated to circulate the liquid in the liquid discharge unit. A liquid ejecting apparatus characterized by adjusting a temperature. A temperature detector for detecting the temperature of the liquid in the liquid discharge head;
A heat exchange unit that adjusts the temperature of the heat medium based on the temperature detected by the temperature detection unit;
A circulation driving unit for circulating the temperature-controlled heat medium in the circulation channel;
The liquid ejection apparatus according to claim 1, further comprising:   The liquid discharge apparatus according to claim 1, wherein the circulation channel is formed through a flexible film body that separates the liquid discharge unit and the heat medium. A housing for accommodating the liquid discharge unit;
4. The liquid ejection apparatus according to claim 1, wherein the circulation channel is disposed in at least a part of the casing. 5.   5. The liquid ejection apparatus according to claim 3, wherein a side opposite to the liquid ejection unit of the flexible film body has a porous structure.   6. The liquid ejection apparatus according to claim 5, wherein the flexible membrane is filled with beads-like fine particles to form a porous structure.   The liquid ejection apparatus according to claim 5, wherein a porous structure is formed by filling the flexible membrane with a gel agent.

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