JP4035940B2 - Inkjet head, inkjet printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inkjet head in which a plurality of channels are arranged in parallel, and an inkjet printer including such an inkjet head.
[0002]
[Prior art]
In an inkjet head in which a plurality of channels are arranged in parallel, a pressure change is generated in each channel by the action of a piezoelectric element or a heating element, and ink is ejected from nozzles provided for each channel.
[0003]
For example, an inkjet head that operates in a shear mode includes a ceramic member called an actuator in which a plurality of channels are formed by excavating grooves parallel to PZT, which is a kind of ceramic, and piezoelectric ceramic is used for partition walls that separate the channels from each other. The ink in the channel is pressurized by the pressure change generated by the shear deformation of the piezoelectric ceramic and ejected from the nozzle.
[0004]
In such an ink jet head, a manifold is provided to distribute ink to each channel, and an image is formed by controlling whether ink is discharged from each channel.
[0005]
A drive signal is supplied from the main body of the ink jet printer to shear the piezoelectric ceramic of each channel. As the above-mentioned manifold, a resin molded member is often directly bonded to the actuator.
[0006]
[Problems to be solved by the invention]
In such an ink jet head, it is known that ink in the ink jet head itself, the channel, and the common ink chamber is heated during driving. The following three points are the main factors related to heating.
(1) Heat generated by the actuator itself, which is heated by heat generated by the heat generating element in the thermal method, and by heat generated by energy loss during shear deformation of the piezoelectric ceramic in the piezo method (operating in the shear mode).
(2) Heat generated by the driving IC that selectively supplies the driving signal to each channel is conducted through the driving signal conductor and heated.
(3) Heated by heat generated by wiring resistance.
[0007]
Since the viscosity of the ink changes according to the temperature condition, when the ink is heated, the volume of the ink droplet per discharge increases even if the pressurization condition is unchanged before and after the heating, resulting in a recorded image. The concentration of may increase. When the viscosity of the ink is remarkably reduced, the air entrained in the nozzle from the nozzle hole becomes bubbles and stays in the channel, and even if pressurized, the bubbles are only compressed and the ink cannot be ejected. Fall into a situation.
[0008]
In addition, since the shear deformation characteristics of the piezoelectric ceramic change according to the temperature condition, when the actuator is heated, even if the drive signal corresponding to one discharge is unchanged, the pressurization condition changes and the discharge per discharge The volume of ink droplets may fluctuate, resulting in unstable recorded image density.
[0009]
Accordingly, an object of the present invention is to provide an ink jet head and an ink jet printer that stabilize the image density by stabilizing the volume of ink droplets per discharge even when an actuator or ink is heated.
[0010]
[Means for Solving the Problems]
  The problems of the present invention can be solved by the ink jet head described in claim 1. That is, the inkjet head according to claim 1
An actuator unit in which print channels for generating pressure changes applied to ink are arranged in parallel;
A manifold section that forms a common ink chamber that is fixed to the actuator and distributes ink to each print channel;
In an inkjet head that discharges ink from nozzles corresponding to each channel by generating a pressure change in each channel,
A temperature detector fixed by an adhesive that bonds the manifold and the actuator to the outside of the common ink chamber;,
The temperature detector is disposed in a gap between the protrusion provided on the manifold and the actuator.It is characterized by that.
The problems of the present invention can be solved by the ink jet head described in claim 2. That is, the ink jet head according to claim 2
An actuator unit in which print channels for generating pressure changes applied to ink are arranged in parallel;
A manifold portion that forms a common ink chamber that is fixed to the actuator and distributes ink to each print channel;
In an inkjet head that discharges ink from nozzles corresponding to each channel by generating a pressure change in each channel,
A temperature detector fixed by an adhesive that bonds the manifold and the actuator to the outside of the common ink chamber;
The manifold is formed outside the common ink chamber so as to surround the common ink chamber, and is formed with a groove portion that communicates from a contact surface between the manifold and the actuator to a surface other than the contact surface of the manifold.
The temperature detection unit is disposed in the groove, and the actuator, the manifold, and the temperature detection unit are bonded to each other by an adhesive injected into the groove.
[0012]
  The subject of the present invention is the claim.7Can be solved by the ink jet printer described in 1. above. That is, the claim7The inkjet printer described in
An actuator unit with parallel print channels that generate pressure changes to the ink, and a manifold unit that forms a common ink chamber that is fixed to the actuator and distributes ink to each print channel. An inkjet head that ejects ink from nozzles corresponding to each channel;
In an inkjet printer comprising a drive signal generator for generating a drive signal to be supplied to each channel,
A temperature detection unit fixed by an adhesive bonding the manifold and the actuator outside the common ink chamber;
A feedback unit that reflects the detection result of the temperature detection unit in the drive signal.,
The temperature detector is disposed in a gap between the protrusion provided on the manifold and the actuator.It is characterized by that.
The problem of the present invention can be solved by the ink jet printer according to the eighth aspect. That is, the inkjet printer according to claim 8 is
An actuator unit with parallel print channels that generate pressure changes to the ink, and a manifold unit that forms a common ink chamber that is fixed to the actuator and distributes ink to each print channel. An inkjet head that ejects ink from nozzles corresponding to each channel;
In an inkjet printer comprising a drive signal generator for generating a drive signal to be supplied to each channel,
A temperature detection unit fixed by an adhesive bonding the manifold and the actuator outside the common ink chamber;
A feedback unit that reflects the detection result of the temperature detection unit in the drive signal;
The manifold is formed outside the common ink chamber so as to surround the common ink chamber, and is formed with a groove portion that communicates from a contact surface between the manifold and the actuator to a surface other than the contact surface of the manifold.
The temperature detection unit is disposed in the groove, and the actuator, the manifold, and the temperature detection unit are bonded to each other by an adhesive injected into the groove.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment relating to an ink jet head of the present invention will be described with reference to FIGS. FIG. 1 is a cross-sectional view showing the configuration of the inkjet head 1, FIG. 2 is a perspective view of the inkjet head 1 disassembled into three parts, and FIG. 3 is a perspective view of the inkjet head 1.
[0015]
In FIG. 1, the actuator 20 is mainly composed of a piezoelectric ceramic in which printing channels (hereinafter simply referred to as channels) 23 having printing nozzles are arranged in parallel. The first manifold 40 and the second manifold 70 are resin members that are bonded to the actuator 20 to form the common ink chamber 41 and the common ink chamber 71, respectively.
[0016]
The actuator 20 is a member that changes the pressure applied to ink by a ceramic member in which a piezoelectric ceramic layer having opposite polarization directions is provided on a long non-piezoelectric ceramic substrate.
[0017]
The actuator 20 has a plurality of channels 23 cut by a diamond blade or the like. Each channel 23 is cut into a linear and elongated groove shape, and the uncut piezoelectric ceramic serves as a partition wall 25 (described later in FIG. 2) of each channel 23. The depth of the channel 23 gradually decreases as it goes to the right in the figure, and finally disappears. A metal electrode (not shown) is formed on a part of the inner surface of the channel 23.
[0018]
The non-piezoelectric ceramic substrate is preferably selected from at least one of alumina, aluminum nitride, zirconia, silicon, silicon nitride, silicon carbide, and quartz, and is polarized even when the partition wall 25 of the channel 23 is shear-deformed. Can be reliably supported.
[0019]
As a piezoelectric ceramic, a ceramic such as PZT, PLZT, etc., mainly a mixed microcrystal of PbOx, ZrOx, TiOx, a trace amount of metal oxide known as a softening agent or a hardening agent, such as Nb, Zn, Mg, Those containing oxides such as Sn, Ni, La, and Cr are preferable.
[0020]
PZT is lead zirconate titanate, which is preferable because it has a high packing density, a large piezoelectric constant, and good workability. When the temperature is lowered after firing, the crystal structure suddenly changes, and PZT becomes a collection of fine crystals in the form of dipoles in which atoms are displaced, one side is positive, and the other side is negative. Such spontaneous polarization is random in direction and cancels polarities with each other, so further polarization processing is required.
[0021]
In the polarization treatment, a PZT thin plate is sandwiched between electrodes, immersed in silicon oil, and polarized by applying a high electric field of about 10 to 35 kv / cm. When a voltage is applied to the polarized PZT at a right angle to the polarization direction, the side wall is sheared and deformed in an oblique direction into a square shape by the piezoelectric sliding effect, and the volume of the ink chamber expands.
[0022]
Gold, silver, aluminum, palladium, nickel, tantalum, and titanium can be used as the material of the metal electrode, and gold and aluminum are particularly preferable from the viewpoint of electrical characteristics and workability. It is formed.
[0023]
A nozzle plate 26 is bonded to the left end of the actuator 20 in the drawing. The nozzle plate 26 is provided with a nozzle 24 corresponding to the position of each channel 23, and is made of plastics such as polyalkylene terephthalate such as PET, polyimide, polyetherimide, polyetherketone, polyethersulfone, polycarbonate, and cellulose acetate. Is formed.
[0024]
Since FIG. 1 is shown in a cross section passing through the longitudinal direction of the channels 23, the arrangement of the channels 23 is not known. Therefore, the arrangement of the channels 23 will be described with reference to FIG.
[0025]
In FIG. 2, a part of the channel 23 is shown. Each channel 23 is cut into a straight and elongated groove shape and includes a partition wall 25. The partition wall 25 undergoes shear deformation to cause a pressure change in the channel 23. The arrangement direction of the plurality of channels 23 is a direction translated in a direction perpendicular to the longitudinal direction Y, and the channels 23 are arranged at equal intervals.
[0026]
In this embodiment, the upper and lower rows are formed in a row in which 256 channels 23 are formed per row. However, since this is complicated, only the upper four are shown in FIG. 1, and the other shapes are the same. The illustration is omitted. Also, only the upper four and the lower four are shown for the nozzles 24, and the others are the same shape and are not shown.
[0027]
As shown in FIG. 1, each channel 23 is formed up to a position reaching the nozzle 24, but FIG. 2 shows only the portions exposed on the surface of the actuator 20 that can be seen from the viewpoint of FIG. The portion hidden by the channel 23 and the exposed portion of the channel 23 corresponding to the lower nozzle 24 are omitted.
[0028]
A description will be given with reference to FIG. 1 again.
At the right end of the actuator 20 in the figure, a signal line 28, which is a collection of signal lines corresponding to each channel 23, is bonded with an epoxy adhesive or the like, and is electrically connected to a metal electrode.
[0029]
The partition wall 25 of each channel 23 is shear-deformed by a drive signal supplied from an ink jet printer main body (not shown) via a signal line 28, and the ink in the channel 23 that receives stress is ejected from the nozzle 24. The ink ejected from the nozzles 24 flies in the longitudinal direction Y (see FIG. 2) of the channel 23 and lands on a recording material such as paper.
[0030]
The first manifold 40 is a resin member that forms the rectangular parallelepiped common ink chamber 41 by attaching the actuator 20, and the first manifold 40 constitutes five of the six surfaces of the common ink chamber 41, while the actuator 20 Constitutes the remaining surface of the common ink chamber 41.
[0031]
The ink flow path 42 is a through path formed in the first manifold 40 and supplies ink to the inside of the common ink chamber 41. The ink flow path 42 is a flow path for supplying ink from an ink tank provided in an ink jet printer main body (not shown). A pipe-shaped resin member or a flexible tube is provided on the right side of FIG. Etc. to be connected to an ink tank (not shown).
[0032]
A filter 50 is disposed at a boundary portion between the ink flow path 42 and the common ink chamber 41. The filter 50 has a mesh-shaped metal member welded to the first manifold 40, and the mesh has a size that reliably removes about 1/3 of the opening diameter of the nozzle 24. Therefore, foreign matter mixed in on the upstream side of the position where the filter 50 is disposed in the ink flow path or remaining from the time of manufacture is prevented from entering the common ink chamber 41 along the ink flow.
[0033]
As described above, each channel 23 includes a portion that gradually becomes shallower, but the portion is exposed to the indoor side of the common ink chamber 41. Accordingly, the ink stored in the common ink chamber 41 is distributed to each channel 23 from the portion.
[0034]
The ink stored in the common ink chamber 41 flows into each channel 23 or flows back from each channel 23 to the common ink chamber 41 according to the shear deformation of each channel 23.
[0035]
The actuator 20 and the first manifold 40 are fixed by adhesion. In the following description, since the actuator 20 and the first manifold 40 are bonded to each other on the surface, the surface is referred to as an adhesive surface, and the edge of the adhesive surface is referred to as an adhesive line.
[0036]
The adhesive injection groove 60 is an example of the groove portion of the present invention, and is a groove provided in the first manifold 40 as a portion where the adhesive is filled. The injection groove outer frame is formed on the outer periphery of the main body block 40a of the first manifold 40. This is a gap between the main body block 40a and the injection groove outer frame portion 40b formed when the portion 40b is provided with a predetermined width. The injection groove outer frame portion 40b is supported by an injection groove support portion 40c (see FIGS. 2 and 3) as will be described later.
[0037]
Like the second manifold 70, the adhesive injection groove 60 is preferably composed of a wide width portion 72 in which an adhesive injection needle (hereinafter also referred to as a needle) N can be inserted and a narrow width portion 73 in which insertion is impossible. The adhesive injection groove 60 does not have a wide portion and a narrow portion in the cross section shown in FIG. 1, but is provided in other cross sections.
[0038]
Depending on the size of the needle N, the wide portion has a width of about 0.8 mm to 1.5 mm, and the narrow portion has a width of about 0.1 mm to 0.8 mm. When such a wide part and a narrow part are provided and the narrow part is located near the actuator 20, the needle N can be prevented from damaging the surface of the actuator 20.
[0039]
The air vent 64 is an air vent for releasing the air pushed by the injected adhesive from the adhesive injection groove 60. The air vent 64 floats and fixes the injection groove outer frame portion 40b so that the distance between the injection groove outer frame portion 40b and the actuator 20 is 0.01 mm to 0.2 mm, and thereby the injection groove outer frame portion 40b It is configured as a gap with the actuator 20.
[0040]
By providing such an air vent 64, the adhesive injected into the adhesive injection groove 60 gradually flows down due to gravity, and finally the air in the adhesive injection groove 60 is pushed out as it reaches the bonding surface. Good adhesion is possible with the above-mentioned adhesion line.
[0041]
The injection amount mark 66 is a parting line provided in the adhesive injection groove 60 and is a guideline for the bonding operator to determine the timing of releasing the needle N. The injection amount mark 66 may be any of engraving, painting, a step provided at the time of resin formation, and the like. In the present embodiment, it is provided on the main body block 40a side, but it may be provided on the injection groove outer frame portion 40b side.
[0042]
The thermistor 80 is an example of the temperature detector of the present invention, and is fixed so as to contact the actuator 20 inside the adhesive injection groove 60. The thermistor 80 is fixed by the adhesive injected into the adhesive injection groove 60.
[0043]
The cable 81 connects the thermistor 80 and a control board (described later) included in the ink jet printer main body, and a detection signal output by the thermistor 80 according to a temperature change of the actuator 20 is transmitted to the control board.
[0044]
The locking projection 82 is a projection for temporarily fixing the thermistor 80 before the adhesive injection and during the adhesive injection operation so that the thermistor 80 does not come off, and for securing the thermistor 80 more securely after the adhesion. As will be described later, the thermistor 80 is slid inside the adhesive injection groove 60 to temporarily pass between the locking projection 82 and the actuator 20, so that the distance between the actuator 20 and the locking projection 82 is the clearance with respect to the thermistor 80. Is expected. Although this embodiment is an example in which the actuator 20 and the thermistor 80 are in direct contact, there is no particular problem even if an adhesive enters between the thermistor 80 and the actuator 20 and is fixed in a state separated by about 1 millimeter. .
[0045]
It is desirable that the thermistor 80 be disposed in the immediate vicinity of the channel 23 provided in the actuator 20. Here, the immediate vicinity of the channel 23 is a portion on the surface of the actuator 20 that reaches the shortest distance from the channel 23. In the present embodiment, since the thermistor 80 is disposed outside the common ink chamber 41 formed by bonding the first manifold 40 and the actuator 20, the nozzle passes through the nozzle surface where the nozzles of the respective channels are disposed. The thermistor 80 has a first surface as a second surface and a plane that passes through the common ink chamber and is parallel to the nozzle surface and has the smallest distance from the nozzle surface. It is arranged at a site that is closest to the channel 23 in the space between the two surfaces.
[0046]
If the thermistor 80 is arranged in such a part, the temperature of the channel 23 can be reliably detected. For example, when configuring a feedback system that reflects the detection result in the drive signal, an accurate detection result can be obtained. Is possible. In addition, since the thermistor 80 is disposed outside the common ink chamber 41, the cable 81 is not sealed well and the risk of ink leakage can be prevented.
[0047]
When the temperature distribution of the actuator 20 is measured, only a temperature difference of 2 to 3 degrees (Celsius) is generated. Therefore, as long as the position is closest to the channel 23, it may be closest to any one of the plurality of channels 23.
[0048]
In the present embodiment, the thermistor 80 is simply dropped into the adhesive injection groove 60, but a fitting portion may be provided in the resin portion constituting the first manifold 40 and fixed. Further, the procedure for fixing the thermistor 80 by bonding is that the thermistor 80 is fixed to the first manifold 40, the thermistor 80 and the actuator 20 are stacked, and then the adhesive is injected into the adhesive injection groove 60. good.
[0049]
As described above, when the actuator 20 and the first manifold 40 are bonded, the common ink chamber 41 is formed, so that the ink supplied from the ink flow path 42 is distributed to each channel 23. In addition, since the portions other than the ink flow path 42 and the nozzle 24 are sealed, ink leakage can be prevented.
[0050]
The ink jet head 1 configured as described above ejects ink from the nozzles 24 when a driving signal corresponding to a desired image is supplied from the signal line 28, and supplies the consumed amount of ink from the common ink chamber 41 to each channel 23. Therefore, continuous discharge becomes possible.
[0051]
In the cross section shown in FIG. 1, the shape is a substantially vertical shape, and the configuration around the first manifold 40 and the second manifold 70 is the same.
[0052]
Next, a procedure for bonding the actuator 20, the first manifold 40, the second manifold 70, and the thermistor 80 will be described with reference to FIGS. 2, 3, and 4. FIG. 4 is a schematic diagram for explaining a procedure for temporarily fixing the thermistor 80 inside the adhesive injection groove 60.
[0053]
First, in the drawing, the second manifold 70, the actuator 20, the first manifold 40, and the thermistor 80 are arranged in order from the bottom. By superimposing these, for the actuator 20 and the first manifold 40, the vertical plane A1 of the actuator 20 and the vertical plane B of the first manifold 40 are combined, and the horizontal plane C1 of the actuator 20 and the horizontal plane D of the first manifold 40 are combined. . For the actuator 20 and the second manifold 70, the vertical plane A2 of the actuator 20 and the vertical plane E of the second manifold 70 are combined, the horizontal plane C2 of the actuator 20 and the horizontal plane F of the second manifold 70 are combined, and the thermistor As for 80, when the locking projection 82 is passed through and temporarily fixed inside the adhesive injection groove 60, the state shown in FIG. 3 is obtained.
[0054]
The first manifold 40 and the second manifold 70 are provided with misassembly prevention protrusions 43 and 73, respectively, and the actuator 20 is provided with the misassembly prevention grooves 27a and 27b on the top and bottom. The problem of assembling can be prevented.
[0055]
Before the overlapping, a part of each channel 23 (the above-mentioned gradually shallowing portion) is exposed by the actuator 20, but when overlapped with the first manifold 40 and the second manifold 70, the inside of the common ink chamber 41 is inside. Sealed.
[0056]
Next, a procedure for temporarily fixing the thermistor 80 will be described with reference to FIG. 4 (A) and 4 (B) are schematic views in which the inside of the adhesive injection groove 60 is taken out, and the dividing line L1 indicates the above-described adhesive line where the actuator 20 and the first manifold 40 are in contact with each other. The body block 40a rises from this line. A dividing line L2 indicates a leg of a perpendicular line drawn from the injection groove outer frame portion 40b to the actuator 20. Both the dividing line L1 and the dividing line L2 are virtual lines on the surface of the actuator 20.
[0057]
The thermistor 80 is placed in contact with the actuator 20 inside the adhesive injection groove 60 and is slid in the direction of arrow Z. The locking projection 82 is fixed to the main body block 40a and the injection groove outer frame portion 40b, and is floated from the surface of the actuator 20 so that the thermistor 80 can be passed. Accordingly, when the thermistor 80 slides in the direction of the arrow Z, the thermistor 80 fits between the locking projection 82 and the actuator 20 as shown in FIG. The locking projection 82 is provided with a notch 83, and the cable 81 can be routed outside the adhesive injection groove 60 while the thermistor 80 is held between the locking projection 82 and the actuator 20.
[0058]
In this way, the thermistor 80 is temporarily fixed inside the adhesive injection groove 60.
When the thermistor 80 is temporarily fixed and the second manifold 70, the actuator 20, and the first manifold 40 are overlapped, the adhesive is then injected into the adhesive injection groove 60. The injection of the adhesive is performed using a tubular needle N that discharges the adhesive from the tip.
[0059]
In FIG. 3, the needle N is moved along the adhesive injection groove 60 while inserting the needle N (not shown) into the adhesive injection groove 60 and discharging the adhesive. Since the adhesive discharged from the needle N gradually flows down and fills the inside of the adhesive injection groove 60, the air inside the adhesive injection groove 60 pushed out by the adhesive escapes from the air vent 64.
[0060]
The flowing down adhesive reaches the air vent 64 and tends to flow out of the air vent 64. At the air vent 64 portion, the meniscus forms a predetermined contact angle with the injection groove outer frame portion 40b and the actuator 20 as the wall surface. (Not shown) is formed. Therefore, the adhesive does not flow out of the air vent 64 indefinitely. The interval between the air vents 64 is in the range of 0.01 millimeters to 0.2 millimeters. The said space | interval is a space | interval by the shortest distance of the actuator 20 and the injection groove outer frame part 40b, and is selected by the physical property of an adhesive agent.
[0061]
The adhesive flowing down to the air vent 64 seals the bond line between the actuator 20 and the first manifold 40 and fixes the actuator 20 and the first manifold 40 to each other. Further, since the thermistor 80 is bonded at the temporarily fixed position, the thermistor 80 is fixed to the position closest to the channel 23 inside the adhesive injection groove 60.
[0062]
The above is an explanation of the cross section of interest in the adhesive injection groove 60. As shown in FIG. 2 and FIG. 3, the adhesive injection groove 60 is formed over the entire circumference of the first manifold 40. The needle N is moved along the groove 60 and the adhesive is injected over the entire circumference of the first manifold 40.
[0063]
In the present embodiment, the adhesive injection groove 60 is filled with the adhesive by the flow of the adhesive. Therefore, after the adhesive between the actuator 20 and the first manifold 40 is solidified, the ink jet head 1 in the state shown in FIG. The top and bottom are reversed, and the adhesion work (injection of adhesive) between the actuator 20 and the second manifold 70 is performed.
[0064]
In the present embodiment, the thermistor 80 is attached to the first manifold 40 so as to be in contact with the actuator 20 to detect the temperature of the actuator 20, but the thermistor 80 may be similarly attached to the second manifold 70.
[0065]
Further, since the thermistor 80 is fixed inside the adhesive injection groove 60, it is protected and the influence of the temperature can be avoided, and the thermistor 80 is bonded by an adhesive that bonds the actuator 20 and the first manifold 40. As a result, the waste of the adhesive can be eliminated.
[0066]
Next, an embodiment relating to the ink jet printer of the present invention will be described with reference to FIG. The ink jet printer according to the present embodiment includes a power supply unit, a control board, a paper feed unit, a paper discharge unit, a carriage unit (platen unit) including the four ink jet heads 1 described with reference to FIGS. This is a color inkjet printer that includes an ink storage unit and ejects ink droplets of different colors such as yellow, magenta, cyan, and black for each inkjet head 1. Well-known techniques can be used for the mechanical configuration of the power supply unit, carriage unit (platen unit), paper supply unit, paper discharge unit, ink storage unit, etc. explain.
[0067]
FIG. 5 is a control block diagram of the inkjet printer 1.
The control board 100 is mounted with a CPU 101 that controls the entire inkjet printer 1, and is connected to a head driver IC 121 provided in the carriage 120. The head driver IC 121 is an example of a drive signal generator of the present invention.
[0068]
The page memory 102 stores image data received from a personal computer or the like that uses the inkjet printer 1 itself as a peripheral device. The storage capacity of the page memory 102 may be determined by the number of bits of gradation image data handled by a personal computer or the like, the number of dots, the signal transfer speed, the CPU processing speed, and the like.
[0069]
The inkjet printer 1 includes a parallel interface SCSI (104a) and IEEE1284 (104b) as interfaces.
[0070]
The line memories 103a and 103b store image data of each pixel recorded in a line in the main scanning direction when recording on a recording sheet. The data signal line from the page memory 102 is 16 bits and branches to each line memory 103 by 8 bits. The image data in the line memories 103a and 103b is serially transferred to the head driver IC 121 via a cable.
[0071]
One head driver IC 121a-d is provided for each color. Each color inkjet head 1Y, M, C, K has 256 nozzles, and the nozzles constituting each nozzle row are arranged side by side in the sub-scanning direction so that a plurality of lines can be recorded simultaneously.
[0072]
The yellow image data is transferred from the line memory 103a to the head driver IC 121a. The 128 yellow image data transferred to the head driver IC 121a are processed in parallel, and printing by the inkjet head 1Y is executed. Similarly, the magenta image data is transferred from the line memory 103a to the head driver IC 121b and is recorded by the inkjet head 1M. Cyan is transferred from the line memory 103b to the head driver IC 121c and recording is performed by the inkjet head 1C, and black is transferred from the line memory 103b to the head driver IC 121d and recording is performed by the inkjet head 1K.
[0073]
The system ROM 105 stores a waveform corresponding to the temperature condition as digital data. The system ROM 105 can be configured using an EPRROM or the like.
[0074]
The CPU 101 reads out waveform data optimum for the temperature conditions detected by the thermistors 80Y, 80M, 80C, 80K from the system ROM 105 and sends it to the drive waveform generation circuit 106. The drive waveform generation circuit 106 demodulates and amplifies the optimum waveform data into an analog waveform by D / A conversion to obtain a drive signal and outputs it to the head driver IC 121.
[0075]
The system ROM 105 stores drive signal waveform data in which the applied voltage is changed for each temperature condition. Specifically, since the viscosity of the ink decreases as the temperature increases, the applied voltage (wave height) of the drive signal is lowered.
[0076]
A block configured by the system ROM 105 and the drive waveform generation circuit 106 is an example of the feedback unit of the present invention.
[0077]
The encoder 107 is a position detection unit that detects the position of the carriage 120, and optically detects in this embodiment.
[0078]
The AND gate 108 outputs a TRGIN signal for starting ink ejection when the carriage unit 120 starts one reciprocating movement based on the information detected by the encoder 107 and reaches a predetermined position on the forward path. The signal is output to the head driver IC 121 through 109. The head driver IC 121 receives this TRGIN signal and sends a drive signal to each nozzle of the inkjet head 1.
[0079]
The head driver IC 121 sends a drive signal to the partition walls 25 made of piezoelectric ceramic provided at each nozzle of the inkjet head 1 by a 128-bit data signal line. In response to this drive signal, the partition wall 25 is deformed to pressurize the ink, and the ink in the head is ejected. The head driver IC 121 includes 256 driving circuits each composed of a shift register, a latch, and a switching element (transistor) for each channel in parallel.
[0080]
Based on the data transferred from the line memory 103, each drive circuit selectively determines whether or not ink is ejected for each channel when the TRGIN signal is given. The channel for ejecting ink obtains the drive signal supplied from the drive waveform generation circuit 106 via the shift register, latch, and switching element, and ejects ink in synchronization with the other channels.
[0081]
As described above, the detection result of the detection signal output from the thermistors 80Y, 80M, 80C, and 80K according to the temperature change of the actuator 20 is fed back to the drive signal output from the drive waveform generation circuit 106.
[0082]
In the ink jet printer of the present embodiment, the partition wall 25 is shear-deformed, so that the number of channels per ink jet head can be increased and the number of ink droplets ejected from one head per time can be increased. In addition, it is possible to increase the number of ink droplets ejected per time from one channel by increasing the driving frequency of the driving IC.
[0083]
Such an ink jet head increases heat generation and is easily affected by heat. By applying the present invention, the volume of ink droplets per discharge can be stabilized even when the actuator or ink is heated. The image density can be stabilized.
[0084]
In the present embodiment described above, an example in which a thermistor is used as an example of the temperature detection unit of the present invention has been described. However, a well-known temperature detection element such as a thermocouple can be used.
[0085]
Further, instead of the configuration in which the waveform data optimal for the temperature condition is read from the system ROM 105, the CPU 101 may be configured to calculate the waveform optimal for the temperature condition.
[0086]
【The invention's effect】
According to the ink jet head of claim 1, since the temperature detection unit is disposed at a position that suitably detects the temperature of the heated actuator or ink, in an ink jet printer that employs such an ink jet head, It is possible to stabilize the image density by feeding back the detection result and stabilizing the volume of the ink droplet per discharge.
[0087]
  Claim7According to the ink jet printer described in (1), it is possible to stabilize the image density by stabilizing the volume of ink droplets per discharge even when the actuator or ink is heated.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration of an inkjet head.
FIG. 2 is a perspective view of an inkjet head.
FIG. 3 is an exploded perspective view of an inkjet head divided into three parts.
FIG. 4 is a schematic diagram illustrating a procedure for temporarily fixing a thermistor inside an adhesive injection groove.
FIG. 5 is a control block diagram of the ink jet printer.
[Explanation of symbols]
1 Inkjet head
20 Actuator
23 channels
24 nozzles
40 First manifold
40a body block
40b Outer groove outer frame
41 Common ink chamber
60 Adhesive injection groove
70 Second manifold
80 thermistor
105 System ROM
106 Drive waveform generation circuit
121 Head Driver IC

Claims (12)

An actuator unit in which print channels for generating pressure changes applied to ink are arranged in parallel;
A manifold section that forms a common ink chamber that is fixed to the actuator and distributes ink to each print channel;
In an inkjet head that discharges ink from nozzles corresponding to each channel by generating a pressure change in each channel,
A temperature detector fixed by an adhesive that bonds the manifold and the actuator to the outside of the common ink chamber ;
The temperature detection unit, an ink jet head is characterized that you have been placed in the gap of the protrusions and the actuator provided in the manifold. An actuator unit in which print channels for generating pressure changes applied to ink are arranged in parallel;
A manifold portion that forms a common ink chamber that is fixed to the actuator and distributes ink to each print channel;
In an inkjet head that discharges ink from nozzles corresponding to each channel by generating a pressure change in each channel,
A temperature detector fixed by an adhesive that bonds the manifold and the actuator to the outside of the common ink chamber;
The manifold is formed outside the common ink chamber so as to surround the common ink chamber, and is formed with a groove portion that communicates from a contact surface between the manifold and the actuator to a surface other than the contact surface of the manifold.
The ink jet head according to claim 1, wherein the temperature detector is disposed in the groove, and the actuator, the manifold, and the temperature detector are bonded by an adhesive injected into the groove . The inkjet head according to claim 2, wherein the temperature detection unit is disposed in a gap between a protrusion provided on the manifold and the actuator . The manifold includes a main body block that forms the common ink chamber, and an outer frame portion that is attached to the main body block in a state where a gap serving as the groove portion is provided on an outer periphery of the main body block. Item 4. The ink jet head according to Item 2 or 3 . The inkjet head according to claim 1, wherein the temperature detection unit is disposed in the immediate vicinity of the channel . The inkjet head according to any one of claims 1 to 5, wherein the partition walls separating the channels are made of piezoelectric ceramic . An actuator unit with parallel print channels that generate pressure changes to the ink, and a manifold unit that forms a common ink chamber that is fixed to the actuator and distributes ink to each print channel. An inkjet head that ejects ink from nozzles corresponding to each channel;
In an inkjet printer comprising a drive signal generator for generating a drive signal to be supplied to each channel,
A temperature detection unit fixed by an adhesive bonding the manifold and the actuator outside the common ink chamber;
A feedback unit that reflects the detection result of the temperature detection unit in the drive signal;
The ink jet printer , wherein the temperature detection unit is disposed in a gap between a protrusion provided on the manifold and the actuator . An actuator unit with parallel print channels that generate pressure changes to the ink, and a manifold unit that forms a common ink chamber that is fixed to the actuator and distributes ink to each print channel. An inkjet head that ejects ink from nozzles corresponding to each channel;
In an inkjet printer comprising a drive signal generator for generating a drive signal to be supplied to each channel,
A temperature detection unit fixed by an adhesive bonding the manifold and the actuator outside the common ink chamber;
A feedback unit that reflects the detection result of the temperature detection unit in the drive signal;
The manifold is formed outside the common ink chamber so as to surround the common ink chamber, and is formed with a groove portion that communicates from a contact surface between the manifold and the actuator to a surface other than the contact surface of the manifold.
The temperature sensor is disposed in the groove, and the actuator, the manifold, and the temperature detector are bonded to each other by an adhesive injected into the groove . The inkjet printer according to claim 8, wherein the temperature detection unit is disposed in a gap between a protrusion provided on the manifold and the actuator . The manifold includes a main body block that forms the common ink chamber, and an outer frame portion that is attached to the main body block in a state where a gap serving as the groove portion is provided on an outer periphery of the main body block. Item 10. The ink jet printer according to Item 8 or 9 . The inkjet printer according to claim 7, wherein the temperature detection unit is disposed in the vicinity of the channel. The inkjet printer according to any one of claims 7 to 11, wherein the partition walls separating the channels are made of a piezoelectric ceramic.

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