JP2001315355A - Ink jet head and ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head and an ink jet printer which stabilize an image density by stabilizing a volume of ink drops for every discharge even when an actuator or the ink is heated. SOLUTION: This ink jet head includes an actuator having printing channels arranged side by side for generating a pressure change to be applied to the ink, and a manifold which is fixed to the actuator to form a common ink chamber for dispensing the ink to each of the printing channels, in which the pressure change is generated at each of channels, thereby discharging the ink from nozzles corresponding to the channels. The ink jet head has a temperature- detecting part mounted to the manifold outside the common ink chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head having a plurality of channels arranged in parallel and an ink jet printer having such an ink jet head.

[0002]

2. Description of the Related Art In an ink jet 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 a nozzle provided for each channel.

For example, an ink jet head operating in a shear mode includes a ceramic member called an actuator in which a plurality of channels are formed by excavating a groove parallel to PZT, which is a kind of ceramic, and a piezoelectric member is provided on a partition wall separating the channels from each other. A piezoelectric ceramic is arranged, and the ink in the channel is pressurized by a pressure change generated by shear deformation of the piezoelectric ceramic, and is ejected from a nozzle.

In such an ink jet head, a manifold is provided to distribute ink to each channel, and an image is formed by controlling whether or not ink is ejected from each channel.

[0005] A drive signal is supplied from the ink jet printer main body to shear-deform the piezoelectric ceramic of each channel. In many cases, a resin molded member is directly bonded to the actuator as the above-mentioned manifold.

[0006]

In such an ink jet head, it is known that the ink jet head itself and the ink in the channel or the common ink chamber are heated during driving. The following three points are the main factors related to heating. (1) Heat generated by the actuator itself. In the thermal method, the actuator is heated by heat generated by a heating element. In the piezo method (operating in a shear mode), the actuator is heated by heat generated by energy loss during shear deformation of the piezoelectric ceramic. (2) The heat generated by the driving IC for selectively supplying the driving signal to each channel is conducted through the driving signal conductor and heated. (3) Heated by heat generated by wiring resistance.

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 pressurizing condition does not change before and after the heating. In some cases, the density of the processed image may increase. If the viscosity of the ink drops significantly, the air entrapped in the nozzle from the nozzle hole will remain as bubbles in the channel, and even if pressurized, the bubbles will only be compressed, making it impossible to eject ink. Fall into a situation.

Further, since the shear deformation characteristic of the piezoelectric ceramic changes according to the temperature condition, when the actuator is heated, even if the drive signal corresponding to one discharge is not changed,
When the pressure condition changes, the volume of the ink droplet per discharge varies, and as a result, the density of the recorded image may become unstable.

Accordingly, an object of the present invention is to provide an ink jet head and an ink jet printer which stabilize the image density by stabilizing the volume of ink droplets per discharge even when the actuator or ink is heated.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is as set forth in claim 1.
Can be solved by the inkjet head described in (1). That is, the ink jet head according to the first aspect of the present invention forms an actuator section in which print channels for generating a pressure change applied to ink are arranged in parallel, and a common ink chamber fixed to the actuator and distributing ink to each print channel. An inkjet head that includes a manifold unit and generates a pressure change in each channel to discharge ink from a nozzle corresponding to each channel, further comprising a temperature detection unit attached to the manifold outside the common ink chamber. And

According to the ink jet head of the present invention, the temperature detector is disposed at a position where the temperature of the heated actuator or the ink is suitably detected.
With an ink jet printer employing such an ink jet head, it is possible to stabilize the image density by feeding back the detection result to stabilize the volume of the ink droplet per ejection.

Further, the object of the present invention can be solved by an ink jet printer according to the fifth aspect. That is, an ink jet printer according to the present invention has an actuator section in which print channels for generating a pressure change applied to ink are arranged in parallel, and a manifold that is fixed to the actuator and forms a common ink chamber that distributes ink to each print channel. An inkjet printer comprising: an inkjet head that generates a pressure change in each channel to eject ink from a nozzle corresponding to each channel; and a drive signal generator that generates a drive signal to be supplied to each channel. A temperature detection unit attached to the manifold outside the common ink chamber; and a feedback unit that reflects a detection result of the temperature detection unit on the drive signal.

According to the ink jet printer of the fifth aspect, even when the actuator or the ink is heated, it is possible to stabilize the volume of the ink droplet per ejection and stabilize the image density.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment relating to an ink jet head of the present invention will be described with reference to FIGS. FIG. 1 is a 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.

In FIG. 1, an 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 bonded to the actuator 20 to form the common ink chamber 41 and the common ink chamber 71, respectively.

The actuator 20 is a ceramic member comprising a long non-piezoelectric ceramic substrate provided with a piezoelectric ceramic layer whose polarization directions are opposite to each other, and is a member for giving a pressure change to ink.

The actuator 20 has a plurality of channels 23 cut by a diamond blade or the like. Each of the channels 23 is cut into a linear and elongated groove shape, and the remaining piezoelectric ceramics serve as partition walls 25 (described later in FIG. 2) of each channel 23. The depth of the channel 23 gradually becomes shallower toward the right in the figure, and finally disappears. Channel 2
A metal electrode (not shown) is formed on a part of the inner surface of 3.

The non-piezoelectric ceramic substrate is preferably selected from at least one of alumina, aluminum nitride, zirconia, silicon, silicon nitride, silicon carbide, and quartz.
Even when the piezoelectric ceramic is subjected to shear deformation, the polarized piezoelectric ceramic can be reliably supported.

As piezoelectric ceramics, PZT, PLZ
Ceramics such as T, mainly PbOx, ZrOx, TiO
x in a mixed microcrystal, a trace amount of a metal oxide known as a softening agent or a hardening agent, for example, Nb, Zn, Mg,
Those containing oxides such as Sn, Ni, La, and Cr are preferable.

PZT is lead zirconate titanate,
It is preferable because the packing density is large, the piezoelectric constant is large, and the workability is good. When the temperature is lowered after firing, the crystal structure changes suddenly, resulting in a dipole-like group of fine crystals in which atoms are displaced, one side is positive, and the other side is negative. Since such spontaneous polarization has a random direction and the polarities cancel each other, further polarization processing is required.

In the polarization treatment, a thin plate of PZT is sandwiched between electrodes,
It is 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 in a direction perpendicular to the direction of polarization, the side wall is sheared and deformed in a diagonal direction by a piezoelectric sliding effect to expand the volume of the ink chamber.

As the material for the metal electrode, gold, silver, aluminum, palladium, nickel, tantalum, and titanium can be used. In particular, from the viewpoint of electrical characteristics and workability,
Gold and aluminum are good and are formed by plating, vapor deposition, and sputtering.

A nozzle plate 26 is adhered 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 polyalkylene terephthalate such as PET, polyimide, polyetherimide, polyetherketone, or the like.
It is formed of plastics such as polyethersulfone, polycarbonate, and cellulose acetate.

FIG. 1 shows a cross section passing through the longitudinal direction of the channel 23, so that the arrangement of the channels 23 cannot be understood. Therefore, the arrangement of the channels 23 will be described with reference to FIG.

FIG. 2 shows a part of the channel 23. Each channel 23 is cut into a straight and elongated groove shape and has a partition wall 25. Due to the shear deformation of the partition wall 25, a pressure change in the channel 23 occurs. The direction in which the plurality of channels 23 are arranged is a direction parallel to the direction perpendicular to the longitudinal direction Y, and the channels 23 are arranged at equal intervals.

In the present embodiment, the upper and lower rows are formed with 256 channels 23 formed in one row. However, only four upper rows are shown in FIG. It is not shown in the figure because of its shape. Also, nozzle 2
As for 4, only the upper four and the lower four are shown, and the others have the same shape and are not shown.

The individual channels 23 are formed up to the position reaching the nozzle 24 as shown in FIG. 1, but in FIG. 2, only the portions exposed on the surface of the actuator 20 that can be seen from the viewpoint of FIG. The portions hidden inside and the exposed portions of the channel 23 corresponding to the lower nozzle 24 are omitted.

Description will be made again with reference to FIG. At the right end of the actuator 20 in the figure, a signal line 28 in which signal lines corresponding to the respective channels 23 are combined is adhered by an epoxy-based adhesive or the like, and is electrically connected to a metal electrode.

The partition wall 25 of each channel 23 has a signal line 28
The ink in the channel 23 that has undergone shear deformation due to the drive signal supplied from the ink jet printer main body (not shown) through the process and is subjected to stress is ejected from the nozzle 24. The ink discharged from the nozzles 24 flies in the longitudinal direction Y of the channel 23 (see FIG. 2) and lands on a recording material such as paper.

The first manifold 40 is a resin member that forms the rectangular parallelepiped common ink chamber 41 by mounting the actuator 20. The first manifold 40 forms five of the six surfaces of the common ink chamber 41. On the other hand, the actuator 20 forms the remaining one surface of the common ink chamber 41.

The ink flow path 42 includes a first manifold 40
And supplies the ink to the indoor side 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), and a pipe-shaped resin member or a flexible tube is provided on the right side of FIG. Is connected to an ink tank (not shown).

A filter 50 is provided at a boundary between the ink flow path 42 and the common ink chamber 41. The filter 50 is made of a mesh-shaped metal member and is made of the first manifold 4.
0, and the mesh is sized to reliably remove foreign matter of about 1/3 of the diameter of the opening of the nozzle 24. Therefore, it is possible to prevent foreign matter that has been mixed in the ink flow path upstream of the position where the filter 50 is arranged or that has remained from the time of manufacture from entering the common ink chamber 41 along with the flow of ink.

As described above, each channel 23 has a portion that becomes gradually shallower.
1 is exposed on the indoor side. Therefore, the ink stored in the common ink chamber 41 is distributed to each channel 23 from the relevant portion.

The ink stored in the common ink chamber 41 flows into each channel 23 or flows backward from each channel 23 into the common ink chamber 41 in accordance with the shear deformation of each channel 23.

Actuator 20 and first manifold 4
0 is fixed by bonding. In the following description, since the actuator 20 and the first manifold 40 are bonded at a surface where they come into contact, this surface is called a bonding surface, and the edge of the bonding surface is called a bonding line.

The adhesive injection groove 60 is an example of the groove of the present invention, and is a groove provided in the first manifold 40 as a portion to be filled with the adhesive, and is injected into the outer periphery of the main body block 40a of the first manifold 40. This is a gap between the main body block 40a formed when the groove outer frame portion 40b is provided with a predetermined width and the injection groove outer frame portion 40b. The injection groove outer frame portion 40b is supported by an injection groove support portion 40c (see FIGS. 2 and 3) as described later.

The adhesive injection groove 60 is provided in the second manifold 7.
A needle for injecting adhesive, such as 0 (hereinafter also referred to as a needle)
It is preferable to include a wide portion 72 into which N can be inserted and a narrow portion 73 which cannot be inserted. The adhesive injection groove 60 does not have a wide portion and a narrow portion in the cross section shown in FIG. 1, but has the other cross section.

Although it depends on the size of the needle N, the wide part is about 0.8 mm to 1.5 mm, and the narrow part is 0.1 mm to 1.5 mm.
The width is about 0.8 mm. When such a wide portion and a narrow portion are provided and the narrow portion is close to the actuator 20, it is possible to prevent the needle N from damaging the surface of the actuator 20.

The air vent 64 is an air vent for releasing air pushed by the injected adhesive from the adhesive injection groove 60. The air bleed 64 is provided when the distance between the injection groove outer frame portion 40b and the actuator 20 is 0.01 mm to 0.2 mm.
The gap between the injection groove outer frame portion 40b and the actuator 20 is formed by floating and fixing the injection groove outer frame portion 40b so as to have a diameter of 0.025 mm.

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 reduced as it reaches the bonding surface. It is extruded to enable good bonding with the bonding line described above.

The injection amount mark 66 is a parting line provided in the adhesive injection groove 60, and is a guide for the bonding operator to determine the timing of releasing the needle N. The injection amount mark 66 may be any of a step provided at the time of engraving, painting, and resin formation. In this embodiment, the injection amount mark 66 is provided on the main body block 40a side, but may be provided on the injection groove outer frame portion 40b side.

The thermistor 80 is an example of the temperature detector of the present invention, and the actuator 2 is disposed inside the adhesive injection groove 60.
It is fixed so as to be in contact with zero. The thermistor 80 is fixed by the adhesive injected into the adhesive injection groove 60.

The cable 81 connects the thermistor 80 to a control board (to be described later) provided in the ink jet printer main body. A detection signal output from the thermistor 80 in accordance with a temperature change of the actuator 20 is transmitted to the control board.

The locking projection 82 is a projection for temporarily fixing the thermistor 80 so as not to come off before the adhesive is injected and during the adhesive injection work, and for more securely fixing the thermistor 80 after the bonding. As described later, the thermistor 80 is slid inside the adhesive injection groove 60 so that the locking protrusion 82
Since the actuator 20 and the actuator 20 are temporarily fixed to each other, the clearance between the actuator 20 and the locking projection 82 allows for a clearance from the thermistor 80. Although the present embodiment is an example in which the actuator 20 and the thermistor 80 are in direct contact with each other, there is no particular problem if the adhesive enters between the thermistor 80 and the actuator 20 and is fixed at a distance of about 1 mm. .

It is desirable that the thermistor 80 is disposed immediately near the channel 23 provided in the actuator 20. Here, the immediate vicinity of the channel 23 means the channel 23
Means the portion on the surface of the actuator 20 that reaches the shortest distance from the actuator. Further, in the present embodiment, the thermistor 80 is disposed outside the common ink chamber 41 formed by bonding the first manifold 40 and the actuator 20. Therefore, the thermistor 80 passes through the nozzle surface on which the nozzle of each channel is disposed. When the plane is the first plane, and the plane passing through the common ink chamber and parallel to the nozzle plane and having the minimum distance from the nozzle plane is the second plane, the thermistor 80 is connected to the first plane and the second plane. It is arranged at a position immediately adjacent to the channel 23 in the space between the two surfaces.

By arranging the thermistor 80 in such a portion, it is possible to reliably detect the temperature of the channel 23. For example, when forming a feedback system for reflecting the detection result in the drive signal, the accurate detection result can be obtained. Can be obtained. In addition, since the thermistor 80 is disposed outside the common ink chamber 41, the thermistor 80 is disposed inside the common ink chamber 41.
Is arranged, it is possible to prevent the danger of ink leakage due to the failure of sealing of the cable 81 or the like.

When the temperature distribution of the actuator 20 is measured, only a temperature difference of 2 to 3 degrees Celsius occurs. Is also good.

In the present embodiment, the thermistor 80
Is simply dropped into the adhesive injection groove 60, but may be fixed by providing a fitting portion in the resin portion forming the first manifold 40. In addition, the procedure for fixing the thermistor 80 by bonding may be the procedure for fixing the thermistor 80 to the first manifold 40, stacking the thermistor 80 and the actuator 20, and then injecting the adhesive into the adhesive injection groove 60. good.

As described above, the actuator 20
When the first manifold 40 and the first manifold 40 are bonded, the common ink chamber 41 is formed, and 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.

The ink jet head 1 thus configured
When a drive signal corresponding to a desired image is supplied from the signal line 28, ink is ejected from the nozzles 24 and the consumed amount of ink is supplied from the common ink chamber 41 to each channel 23, so that continuous ejection is possible. Become.

The cross section shown in FIG. 1 has a substantially vertically symmetrical configuration, and the configuration around the first manifold 40 and the configuration around the second manifold 70 are the same.

Next, a procedure of bonding the actuator 20, the first manifold 40, the second manifold 70, and the thermistor 80 will be described with reference to FIGS. FIG. 4 is a schematic diagram illustrating a procedure for temporarily fixing the thermistor 80 inside the adhesive injection groove 60.

First, a second manifold 70, an actuator 20, a first manifold 40, and a thermistor 80 are arranged in this order from the bottom. By overlapping these, the vertical plane A1 of the actuator 20 and the vertical plane B of the first manifold 40 are aligned with respect to the actuator 20 and the first manifold 40.
The horizontal plane C1 and the horizontal plane D of the first manifold 40 are aligned. Further, the actuator 20 and the second manifold 7
With respect to 0, the vertical plane A2 of the actuator 20 and the vertical plane E of the second manifold 70 are aligned, the horizontal plane C2 of the actuator 20 is aligned with the horizontal plane F of the second manifold 70. When it is temporarily fixed inside the adhesive injection groove 60 by being passed through, the state shown in FIG. 3 is obtained.

The first manifold 40 and the second manifold 70 are provided with projections 43 and 73 for preventing erroneous assembly, respectively.
The actuator 20 is provided with a mis-assembly preventing groove 27a,
7b, the problem of assembling the actuator 20 upside down can be prevented.

Before overlapping, a part of each channel 23 by the actuator 20 (the aforementioned gradually shallow portion)
Is exposed, but is superimposed on the inside of the common ink chamber 41 when it is overlapped with the first manifold 40 and the second manifold 70.

Next, a procedure for temporarily fixing the thermistor 80 will be described with reference to FIG. FIG. 4 (A) and FIG. 4 (B)
Is a schematic diagram in which the inside of the adhesive injection groove 60 is taken out, and the separating line L1 indicates the above-mentioned bonding line where the actuator 20 and the first manifold 40 are in contact with each other, and the main body block 40a is separated from this line. stand up. The dividing line L2 is formed by moving the actuator 2 from the injection groove outer frame portion 40b.
The foot of the perpendicular line lowered to 0 is shown. Both the dividing line L1 and the dividing line L2 are virtual lines on the surface of the actuator 20.

With the thermistor 80 placed in contact with the actuator 20 inside the adhesive injection groove 60, the arrow Z
Slide in the direction of. The locking projection 82 is provided on 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 pass through. Therefore, 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. A notch 83 is provided in the locking projection 82 so that the thermistor 80
The cable 81 can be routed outside the adhesive injection groove 60 while the cable 81 is kept between the locking projection 82 and the actuator 20.

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, an adhesive is injected into the adhesive injection groove 60 next. The injection of the adhesive is performed using a tubular needle N that discharges the adhesive from the protruding end.

In FIG. 3, the needle N is inserted into the adhesive injection groove 60.
The needle N is moved along the adhesive injection groove 60 while ejecting the adhesive by inserting (not shown). 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.

When the flowing down adhesive reaches the air vent 64,
At this point, the adhesive forms a meniscus (not shown) having a predetermined contact angle with the injection groove outer frame portion 40b and the actuator 20 as a wall surface at the portion of the air vent 64. 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 mm to 0.2 mm. The distance is a distance based on the shortest distance between the actuator 20 and the injection groove outer frame portion 40b, and is selected according to the physical properties of the adhesive.

The adhesive flowing down to the air vent 64 seals the bonding 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 at a position immediately adjacent to the channel 23 inside the adhesive injection groove 60.

The above is a description of the cross section focused on the adhesive injection groove 60. The adhesive injection groove 60 is formed over the entire circumference of the first manifold 40 as shown in FIGS. The needle N is moved along the adhesive injection groove 60 to inject the adhesive over the entire circumference of the first manifold 40.

In this embodiment, since the adhesive is filled in the adhesive injection groove 60 by flowing down the adhesive, the ink jet between the actuator 20 and the first manifold 40 is solidified as shown in FIG. By turning the head 1 upside down, the actuator 20 and the second manifold 7
A bonding operation with 0 (injection of an adhesive) is performed.

In this embodiment, the thermistor 80 is mounted on the first manifold 40 so as to be in contact with the actuator 20 to detect the temperature of the actuator 20. However, the thermistor 8 is similarly mounted on the second manifold 70.
0 may be attached.

Further, the thermistor 80 is connected to the adhesive injection groove 60.
, The protection is provided and the influence of the temperature can be avoided, and the thermistor 80 is bonded by the adhesive for bonding the actuator 20 and the first manifold 40. Can be.

Next, an embodiment of 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) having four ink jet heads 1 already described with reference to FIGS. The color inkjet printer includes an ink storage unit and the like, and ejects ink droplets of different colors, 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, the carriage unit (platen unit), the paper supply unit, the paper discharge unit, the ink storage unit, and the like. explain.

FIG. 5 is a control block diagram of the ink jet printer 1. The control board 100 has a CPU 101 for controlling the entire inkjet printer 1 mounted thereon, and is connected to a head driver IC 121 of the carriage 120. The head driver IC 121 is an example of the drive signal generator of the present invention.

The page memory 102 stores image data received from a personal computer or the like that uses the inkjet printer 1 as a peripheral device. The storage capacity of the page memory 102 may be determined based on the number of bits, the number of dots, the signal transfer speed, the processing speed of the CPU, and the like of the gradation image data handled by the personal computer or the like.

The ink jet printer 1 has a parallel interface SCSI as an interface.
(104a) and IEEE1284 (104b).

The line memories 103a and 103b store image data of respective pixels which are recorded in a line in the main scanning direction when recording on recording paper. The data signal line from the page memory 102 has 16 bits, and each line memory 103 has 8 bits.
Branched bit by bit. The image data of the line memories 103a and 103b is transferred to the head driver IC1 via a cable.
21 is serially transferred.

One head driver IC 121a-d is provided for each color. The inkjet heads 1Y, 1M, 1C, and 1K of each color have 256 nozzles, and the nozzles forming each nozzle row are arranged in the sub-scanning direction so that a plurality of lines can be simultaneously recorded.

The yellow image data is stored in the line memory 10.
3a is transferred to the head driver IC 121a.
Then, the 1 transferred to the head driver IC 121a is
The 28 yellow image data are processed in parallel,
Recording is performed by the inkjet head 1Y. Similarly, the magenta image data is stored in the line memory 103a.
To the head driver IC 121b, and the recording is executed by the inkjet head 1M. Cyan is transferred from the line memory 103b to the head driver IC 121c and printing is performed by the inkjet head 1C, and black is transferred from the line memory 103b to the head driver IC 121d and is printed.
Recording by K is performed.

The system ROM 105 stores a waveform corresponding to a temperature condition as digital data. This system ROM 105 can be configured using an EPRROM or the like.

The CPU 101 includes the thermistors 80Y, 80M,
The optimum waveform data for the temperature condition detected by C and K is read out from the system ROM 105, and the driving waveform generation circuit 106
Send to The drive waveform generating circuit 106 demodulates and amplifies the optimum waveform data into an analog waveform by D / A conversion, obtains a drive signal, and outputs the drive signal to the head driver IC 121.

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 reduced.

The block constituted by the system ROM 105 and the drive waveform generating circuit 106 is an example of the feedback section of the present invention.

The encoder 107 is a position detecting unit for detecting the position of the carriage 120, and in this embodiment, optically detects the position.

The AND gate 108 is connected to the encoder 107
When the carriage unit 120 starts one reciprocating movement and reaches a predetermined position on the outward path based on the information detected by the control unit 1, the control unit 1 sends a TRGIN signal for starting ink ejection.
09 to the head driver IC 121. The head driver IC 121 receives the TRGIN signal and sends a drive signal to each nozzle of the inkjet head 1.

The head driver IC 121 is a partition wall 25 made of piezoelectric ceramic provided for each nozzle of the ink jet head 1 by a 128-bit data signal line.
A drive signal. Upon receiving this drive signal, the partition 25
Deforms, pressurizes the ink, and ejects the ink in the head. The head driver IC 121 includes two driving circuits each including one shift register, one latch, and one switching element (transistor) per channel.
56 systems are provided in parallel.

Each drive circuit selectively determines whether or not to eject ink for each channel when the above-mentioned TRGIN signal is supplied, based on data transferred from the line memory 103. The channel from which ink is to be ejected obtains a drive signal provided from the drive waveform generating circuit 106 via a shift register, a latch, and a switching element, and ejects ink in synchronization with the other channels.

As described above, thermistors 80Y, M, C,
The detection result of the detection signal output by K in response to the temperature change of the actuator 20 is fed back to the drive signal output by the drive waveform generation circuit 106.

In the ink jet printer of this embodiment, since the partition wall 25 is subjected to shear deformation, 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 from one channel per time by increasing the driving frequency of the driving IC.

Such an ink-jet head increases the heat generation and is easily affected by heat. However, by applying the present invention, even if the actuator or the ink is heated, the volume of the ink droplet per discharge can be reduced. It is possible to stabilize the image density.

In the above-described embodiment, an example has been described in which a thermistor is used as an example of the temperature detecting section of the present invention. However, a well-known temperature detecting element such as a thermocouple can be adopted.

Further, instead of reading out the waveform data optimal for the temperature condition from the system ROM 105, the CPU 10
A configuration may be used in which the optimum waveform is calculated for the temperature condition in (1).

[0086]

According to the ink jet head of the present invention, the temperature detecting section is disposed at a position where the temperature of the heated actuator or the ink is suitably detected. Therefore, such an ink jet head is employed. With an ink jet printer, the detection result is fed back to stabilize the volume of an ink droplet per ejection, thereby making it possible to stabilize the image density.

According to the ink jet printer of the fifth aspect, even when the actuator or the ink is heated, the volume of the ink droplet per ejection can be stabilized, and the image density can be stabilized.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an inkjet head.

FIG. 2 is a perspective view of an inkjet head.

FIG. 3 is a perspective view in which an inkjet head is disassembled 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 inkjet printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink jet head 20 Actuator 23 Channel 24 Nozzle 40 First manifold 40a Main body block 40b Injection 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 (8)

[Claims] 1. An actuator unit in which print channels for generating a pressure change applied to ink are arranged in parallel, and a manifold unit fixed to the actuator to form a common ink chamber for distributing ink to each print channel,
An ink jet head that generates a pressure change in each channel and discharges ink from a nozzle corresponding to each channel, further comprising a temperature detection unit attached to the manifold outside the common ink chamber. 2. A groove provided outside the common ink chamber and communicating from a contact surface between the manifold and the actuator to a surface other than the contact surface of the manifold, wherein the temperature detecting unit is provided with the groove. 2. The ink jet head according to claim 1, wherein the ink jet head is mounted on the ink jet head. 3. The ink jet head according to claim 2, wherein the actuator, the manifold, and the temperature detecting unit are bonded by an adhesive injected into the groove. 4. The ink jet head according to claim 1, wherein the temperature detection unit is disposed immediately near the channel. 5. An actuator unit in which print channels for generating a pressure change applied to ink are arranged in parallel, and a manifold unit fixed to the actuator to form a common ink chamber for distributing ink to each print channel,
In an ink jet printer, comprising: an ink jet head that generates a pressure change in each channel to discharge ink from a nozzle corresponding to each channel; and a drive signal generator that generates a drive signal to be supplied to each channel. An ink jet printer comprising: a temperature detection unit attached to the manifold at the outdoor side; and a feedback unit that reflects a detection result of the temperature detection unit to the drive signal. 6. A groove provided outside the common ink chamber and communicating from a contact surface between the manifold and the actuator to a surface other than the contact surface of the manifold, wherein the temperature detecting unit is provided in the groove. 6. The ink jet printer according to claim 5, wherein the ink jet printer is attached to a printer. 7. The ink jet printer according to claim 6, wherein the actuator, the manifold, and the temperature detector are adhered by an adhesive injected into the groove. 8. The ink jet printer according to claim 5, wherein the temperature detection unit is disposed immediately near the channel.