JP3562564B2 - Ink jet recording head - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet recording head that discharges ink droplets from nozzle openings to record images and characters on recording paper by expansion and contraction of a piezoelectric vibrator in a longitudinal vibration mode, and more specifically, a flow path unit and a piezoelectric vibrator. The present invention relates to a structure of a head holder for holding and fixing.
[0002]
[Prior art]
Ink jet recording in which a part of the pressure generating chamber communicating with the nozzle opening and the reservoir is formed of an elastic plate, and the elastic plate is elastically deformed by a piezoelectric vibrator that expands and contracts in the axial direction to expand and contract the pressure generating chamber. The head is characterized in that it can be reduced in size and can be driven at high speed, as compared with a recording head using flexural vibration that deforms in the plane direction.
[0003]
Figure 8 shows an example of an ink jet recording head using a piezoelectric vibrator of the longitudinal vibration mode of the above, the heads B that accommodates the piezoelectric vibrator A in the interior, the passage unit fixing surface C, the adhesive A coating agent is applied, and a flow path unit G formed by laminating an elastic plate D, a flow path forming substrate E, and a nozzle plate F is positioned and pressure-bonded, and a frame body also serving as a protection member for the nozzle plate It is configured to be integrally fixed by H.
[0004]
At the time of this joining, usually, heating to a temperature of about 40 to 100 ° C. is performed to shorten the solidification time of the adhesive.
[0005]
[Problems to be solved by the invention]
However, since the head holder B is made of a polymer material and the channel unit is made of a metal material, the two have different coefficients of thermal expansion. When placed in the environment, thermal stress acts on the joint surface of each member of the flow path unit and head holder due to the temperature difference, the adhesive layer at the joint is peeled off, and the ink droplet from the nozzle opening bends in flight, etc. Fatal damage to the recording head.
In order to solve such problems, if the temperature during the bonding operation is kept low, the bonding strength will decrease, and the solidification of the adhesive will take time, reducing the reliability and work efficiency of the bonding surface. There's a problem.
The present invention has been made in view of such a problem, and an object of the present invention is to reduce recording caused by a difference in a coefficient of thermal expansion between a flow path unit and a head holder without lowering a bonding temperature. An object of the present invention is to provide an ink jet recording head capable of preventing head breakage and flight bending.
[0006]
[Means for Solving the Problems]
In order to solve such a problem, in the present invention, a piezoelectric vibrator unit in which a piezoelectric vibrator is fixed to a fixed substrate, a pressure generating chamber for discharging ink droplets from a nozzle opening , an ink supply port, and a reservoir are provided. In the ink jet recording head, the formed flow path unit is fixed via a head holder, and the piezoelectric vibrator is exposed from a window of the head holder and is brought into contact with the flow path unit. A recess is formed at a position corresponding to the reservoir, and further extends in the direction in which the nozzle openings of each row are arranged in order to reduce the rigidity of the head holder in the region of the recess, and has a width smaller than the width of the recess. A thin groove was formed .
[0007]
[Action]
Since the rigidity of the head holder is weakened by the groove, the head holder is elastically deformed and the stress of the flow path unit is reduced.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Therefore, the details of the present invention will be described below based on the illustrated embodiment.
FIG. 1 is an assembled perspective view showing one embodiment of an ink jet recording head according to the present invention. The ink jet recording head is arranged on an upper surface side around a flow path forming substrate 4 for forming a pressure generating chamber 1, a reservoir 2, and an ink supply port 3. A channel plate 9 having a nozzle plate 6 having a nozzle opening 5, a flow path unit 9 formed of an elastic plate 8 on the lower surface side which is elastically deformed by receiving a displacement of the piezoelectric vibrator 7, and a flow path unit housing the piezoelectric vibrator 7. 9 and a head holder 10 for fixing the upper surface 9.
[0009]
When the flow path forming substrate 7 is formed by anisotropically etching a material having high rigidity, for example, a silicon single crystal substrate, the narrow groove 11 is provided at a key position in the direction in which the nozzle openings of each nozzle opening line are provided. If formed, distortion due to a difference in thermal expansion between the nozzle plate 6 and the elastic plate 8 and the flow path forming substrate 4 can be reduced.
The elastic plate 8 is provided with an ink guide port 12 which is connected to an ink supply pipe of the head holder 10 and supplies ink to the reservoir 2.
[0010]
The head holder 10 exposes an ink supply pipe 14 opening on a flow path unit fixing surface 13 for supporting and fixing the flow path unit 9, a concave portion 15 substantially conforming to the shape of the reservoir 2, and the piezoelectric vibrator 7 at an upper portion. A window 16 is formed.
[0011]
The concave portion 15 provides a deformation space of the elastic plate 8 for sealing the area of the reservoir 2, and absorbs the pressure fluctuation of the ink in the reservoir 2 at the time of discharging the ink droplet by elastically deforming the elastic plate 8. Therefore, in order to prevent the pressure change in the rear, so that a symmetrical ink supply tube 14, open to the atmosphere via the slit-shaped air vent hole 17 which is elongated formed in the column arrangement direction of the nozzle apertures Have been.
[0012]
The head holder having such a structure is formed by injection molding of a thermosetting resin or a thermoplastic resin.
[0013]
In this embodiment, an adhesive is applied to the flow channel unit fixing surface 13 of the head holder 10 so as not to flow into the concave portion 15 and the ink supply pipe 14, or an adhesive sheet formed in a predetermined shape is interposed. Then, the pre-assembled flow path unit 9 is placed thereon, heated to a temperature of about 40 to 100 ° C., and pressed if necessary. At this time, since the groove 11 functions as an adhesive absorption area, it can be prevented from flowing into the ink flow path such as the ink supply pipe 14.
[0014]
At the stage when the bonding is completed, the head holder 10 is positioned so that the flow path unit side faces downward, and the unit body having the plurality of piezoelectric vibrators 7 fixed to the fixed substrate 18 is attached to the tip of the piezoelectric vibrator 7 with an adhesive. Is applied and fixed to the storage chamber 19 of the head holder 10 to complete the recording head.
[0015]
When the bonding operation is completed and the recording head is returned to room temperature, stress is generated between the head holder 10 and the flow path unit 9 due to a difference in the coefficient of thermal expansion. The rigidity of the head holder 10 is weakened by the window 16 for use and the slit-shaped atmosphere opening 17 formed in the recess 15, so that the head holder 10 is elastically deformed to absorb the stress of the flow path unit 9. .
[0016]
Accordingly, even if the temperature during the bonding operation is increased, the thermal stress can be reduced as much as possible, so that the bonding operation can be performed at a high temperature, and the bonding strength and the working efficiency can be improved.
In addition, even if there is a large difference in the coefficient of thermal expansion between the head holder 10 and the flow path unit 9, the stress can be reduced, so that the range of choices of the materials constituting these can be widened and the design flexibility can be improved. Can be.
[0017]
FIGS. 4, 5, and 6 show another embodiment of the present invention. In this embodiment, the ink supply pipe 14 'is elongated along the shape of the concave portion 15 on the side of the flow path unit. Moreover, it is formed in a deep slit shape. Correspondingly, the ink inlet 12 'of the elastic plate 8 is also formed in a slit shape.
[0018]
According to this embodiment, when the bonding operation is completed and the recording head is returned to room temperature, stress is generated between the piezoelectric vibrator 7 and the head holder 10 and the flow path unit 9 due to a difference in thermal expansion coefficient between the two. The rigidity of the head holder 10 is reduced by the exposure window 16 and the elongated ink supply pipe 14 ′, so that the head holder 10 is elastically deformed and the stress of the flow path unit 9 is reduced.
[0019]
Further, at the time of printing, while the ink pressurized by the piezoelectric vibrator 7 is ejected from the nozzle opening 5 as an ink droplet, the ink flows back to the reservoir 2 via the ink supply port 3 to increase the ink pressure of the reservoir 3. However, the pressure increase rate is reduced by the large ink supply port 14 ′, and crosstalk is prevented.
[0020]
Further, since the consumed ink can be replenished from the large opening, the ink droplets can be normally ejected even during graphic printing in which a large amount of ink droplets are ejected instantaneously.
[0021]
FIG. 7 shows another embodiment of the present invention. In this embodiment, an ink supply pipe 14 "is formed at one end of a concave portion 15 of a head holder 10 and the vicinity of the center line of the concave portion 15 is formed. One slit-shaped atmosphere opening port 17 is formed so as to pass therethrough.
[0022]
According to this embodiment, the rigidity of the head holder 10 can be further reduced as compared with the case where the head holder 10 is divided into two parts, and the difference in the thermal expansion coefficient between the flow path unit and the head holder can be reduced. The inconvenience can be solved without fail.
[0023]
In the groove formed by the air opening port 17 and the ink supply pipe 14 ′, the deeper the groove, the greater the ability to relieve the stress. Therefore, the depth of the groove is at least deeper than its width, preferably a through hole. It is desirable to form as.
Further, depending on the shape of the head holder , when the air opening port 17 and the ink supply pipe 14 ′ can be formed to be larger than the length in the direction in which the nozzle openings are arranged, the length is longer than the length in the direction in which the nozzle openings are arranged. It is desirable to improve the stress relieving force of the groove portion by forming a groove portion. Further, a groove portion including a plurality of air opening ports 17 and an ink supply pipe 14 ′ can be formed for one nozzle opening row.
[0024]
【The invention's effect】
As described above, in the present invention, a piezoelectric vibrator unit in which a piezoelectric vibrator is fixed to a fixed substrate, and a flow path unit in which a flow path for discharging ink droplets from a nozzle opening is formed via a head holder In the ink jet type recording head in which the piezoelectric vibrator is fixed and exposed from the window of the head holder and is brought into contact with the flow path unit, the grooves are formed in the head holder in the direction in which the nozzle openings of each row are arranged. By reducing the rigidity of the head holder, the elastic deformation of the head holder can absorb the thermal stress of the flow path unit, making it possible to work at high temperatures, while improving the adhesive strength and work efficiency, and It is possible to prevent breakage and bending of the ink droplet.
[Brief description of the drawings]
FIG. 1 is an assembled perspective view showing one embodiment of an ink jet recording head of the present invention.
FIGS. 2 (a) and 2 (b) are cross-sectional views taken along lines AA and BB in FIG. 3, respectively, showing the cross-sectional structure of the recording head in the direction in which the piezoelectric vibrators are arranged in the recording head.
FIG. 3 is a diagram showing a structure of an upper surface of a head holder of the recording head.
FIG. 4 is an assembled perspective view showing another embodiment of the ink jet recording head of the present invention.
FIGS. 5A and 5B are cross-sectional views taken along lines CC and DD in FIG. 6, respectively, in the direction in which the piezoelectric vibrators of the recording head are arranged in a row.
FIG. 6 is a diagram showing a structure of an upper surface of a head holder of the recording head.
FIG. 7 is a diagram showing a structure of an upper surface of a head holder according to another embodiment of the recording head of the present invention.
FIG. 8 is an assembled perspective view showing one embodiment of a conventional ink jet recording head.
[Explanation of symbols]
2 Reservoir 4 Elastic plate 6 Nozzle plate 7 Piezoelectric vibrator 8 Elastic plate 9 Flow path unit 10 Head holder 11 Slit 12 Ink guide hole 14 Ink supply pipe 15 Recess 17 Open to atmosphere

Claims (8)

A piezoelectric vibrator unit in which the piezoelectric vibrator is fixed to a fixed substrate, and a pressure generating chamber for discharging ink droplets from a nozzle opening, an ink supply port, and a flow path unit in which a reservoir is formed are fixed via a head holder. In an ink jet recording head, the piezoelectric vibrator is exposed from a window of the head holder and is brought into contact with the channel unit.
In the head holder, a recess is formed at a position corresponding to the reservoir, and further extends in the row direction of the nozzle openings in each row in order to reduce the rigidity of the head holder in the area of the recess, and An ink jet recording head, wherein a groove portion smaller than the width of the concave portion is formed. 2. The ink jet recording apparatus according to claim 1, wherein the groove forms an atmosphere opening port for opening the recess to the atmosphere. 2. The ink jet recording head according to claim 1, wherein the groove is formed symmetrically with an ink supply pipe that supplies ink to the reservoir from outside. 3. 3. The ink jet recording head according to claim 2, wherein the ink supply pipe is formed at an end of the reservoir, and the groove is formed continuously from the vicinity of the ink supply pipe to the other end. 2. The ink jet recording head according to claim 1, wherein the groove is formed by elongating the reservoir side of an ink supply pipe that supplies ink to the reservoir from outside. 3. The ink jet recording head according to claim 1, wherein the groove is formed to penetrate the head holder. 2. The ink jet recording head according to claim 1, wherein a length of the groove in the direction in which the nozzle openings are arranged is formed to be larger than a length of the groove in the direction in which the nozzle openings are arranged. 2. The ink jet recording head according to claim 1, wherein a plurality of the grooves are formed for each nozzle opening row.

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