JP4277494B2 - Inkjet head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inkjet head.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, ink jet printers that record predetermined images by ejecting ink onto recording media such as paper and plastic thin plates have been proposed and put into practical use. The ink jet printer includes an ink jet head having nozzles (ink ejection ports), and ejects ink from the nozzles toward the recording medium while moving the ink jet head in a predetermined direction. An image is recorded.
[0003]
In the ink jet printer, ink is ejected by an ink jet head using a piezoelectric element (piezo element) or a heater. The inkjet head includes an inkjet head chip in which nozzles for ejecting ink are arranged in parallel, a manifold that is bonded and fixed to a side portion of the inkjet head chip and guides ink to the inkjet head chip, and a housing that houses the manifold. And a body frame. The inkjet head chip is made of a ceramic piezoelectric element having a low coefficient of thermal expansion, and the manifold is often made of a resin. The housing frame is made of metal or the like.
[0004]
[Problems to be solved by the invention]
By the way, as described above, the inkjet head chip is made of a ceramic piezoelectric element having a low coefficient of thermal expansion, and the manifold is often made of a resin having a high coefficient of thermal expansion. At times and at high temperatures, the manifold may be damaged due to the difference in thermal expansion coefficient (so-called heat shock). Further, when the manifold expands or contracts, the adhesive between the inkjet head chip is peeled off, and there is a possibility that the electrode in the inkjet head chip is damaged.
[0005]
Therefore, an object of the present invention is to provide an ink jet head that can prevent the electrodes in the manifold and the ink jet head chip from being damaged due to a temperature change.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1
An inkjet head chip in which nozzles for ejecting ink are arranged in parallel;
A manifold that is adhesively fixed to a side portion of the inkjet head chip and guides ink to the inkjet head chip;
A housing frame for housing the manifold;
An inkjet head comprising:
The manifold is composed of two members having a higher coefficient of thermal expansion than the inkjet head chip , and at least two positions near the both ends in the nozzle juxtaposition direction on each member of the manifold. is bonded and fixed,
The housing frame has a coefficient of thermal expansion higher than that of the inkjet head chip and lower than that of the manifold .
[0007]
According to the first aspect of the present invention, the members constituting the manifold are bonded and fixed to the housing frame having a lower coefficient of thermal expansion than that of the manifold at least at two locations near both ends in the nozzle juxtaposition direction. It is bonded to a housing frame that has a lower thermal expansion coefficient than the manifold, so that expansion and contraction of the manifold can be suppressed, and damage to the manifold and ink jet head chip electrodes can be prevented.
[0008]
The invention according to claim 2 is the ink jet head according to claim 1,
Engaging portions are provided at both ends of the manifold in the nozzle juxtaposition direction so as to sandwich and fix the inkjet head chip from the both ends.
[0009]
According to the second aspect of the present invention, the manifold is provided with the engaging portion that clamps and fixes the ink jet head chip from both ends in the nozzle juxtaposed direction. The inkjet head chip sandwiched by the engaging portion prevents the contraction, and as a result, it is possible to prevent the manifold from being damaged and the electrodes of the inkjet head chip from being damaged by the contraction of the manifold.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.
[0011]
First, an overall configuration of an ink jet printer according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is an overall configuration diagram of an ink jet printer according to an embodiment of the present invention.
[0012]
As shown in FIG. 1, the ink jet printer 1 of this embodiment includes an ink jet head 2, a carriage 3, a carriage rail 4, a moisture retention unit 5, a maintenance unit 7, an ink tank 25, an ink supply pipe 26, And a control means (not shown).
[0013]
A recording medium 13 on which an image is formed by the ink jet printer 1 is conveyed in the sub-scanning direction orthogonal to the main scanning direction A in FIG. 1 so as to pass through the recording area C in FIG. The recording medium 13 is conveyed by a conveying means (not shown).
[0014]
The carriage 3 carries the inkjet heads 2, 2,... And moves in the direction of arrow A from the home position area B to the maintenance area D along the carriage rail 4. In the recording area C, main scanning on the recording medium 13 is performed by the operation of the carriage 3.
[0015]
During this main scanning, the inkjet head 2 discharges ink toward the recording medium 13 to form an image on the recording medium 13. The inkjet head 2 may be placed vertically so that the nozzle discharge direction is vertically downward, or the inkjet head 2 may be placed horizontally so that the nozzle discharge direction is horizontal. However, the present invention can be implemented in other directions. . In any case, the ink jet head 2 is installed so that the nozzle surface 15b on which the nozzle ejection openings for ejecting ink are arranged faces the recording medium 13.
In the ink jet printer 1 according to the present embodiment, a total of four ink jet heads 2, 2, 2 can be ejected so that four color inks of black (K), yellow (Y), magenta (M), and cyan (C) can be ejected. Are installed on the carriage 3. Another inkjet head 2 is disposed on the back side of the inkjet head 2 shown in the center.
In order to express color, usually four or more inkjet heads are used. Color printers having 4 to 8 inkjet heads are in practical use.
[0016]
The ink tank 25 stores ink to be supplied to the inkjet head 2. One ink tank 25 is installed for one inkjet head 2. The ink supply pipe 26 is installed in such a manner that the ink jet head 2 and the ink tank 25 communicate with each other, and guides ink from the ink tank 25 to the ink jet head 2.
[0017]
The maintenance unit 7 is disposed in the maintenance area D, and includes a suction cap 8, a cleaning blade 11, an ink receiver 12, a suction pump 9, a waste ink tank 10, and the like. The maintenance unit 7 removes foreign matter in the inkjet head 2 through a series of maintenance operations and restores the ink ejection state of the inkjet head 2 to a good state.
[0018]
The suction cap 8 communicates with the waste ink tank 10 via the suction pump 9 and rises during the maintenance operation to cover the nozzle surface 15b of the inkjet head 2. Four suction caps 8 are provided. The suction caps 8, 8,... Can cover the nozzle surfaces 15b, 15b,... Of all the inkjet heads 2, 2,. It is arranged corresponding to the arrangement in
The suction pump 9 includes a cylinder pump and a tube pump. The suction pump 9 operates in a state where the suction cap 8 covers the nozzle surface 15b, thereby generating a suction force for sucking the ink inside the inkjet head 2 together with the foreign matter from the discharge port.
[0019]
The cleaning blade 11 removes ink adhering to the nozzle surface 15b after ink suction of the inkjet head 2. Thereafter, the ink receiver 12 receives ink preliminarily ejected by the inkjet head 2. The waste ink tank 10 stores ink sucked from the ink jet head 2 by the operation of the suction pump 9 and ink preliminarily ejected from the ink jet head 2.
[0020]
The moisturizing unit 5 is disposed in the home position region B and includes moisturizing caps 6, 6,. The moisture retaining cap 6 retains the ink of the inkjet heads 2, 2,... By covering the nozzle surface 15b when the inkjet head 2 is in a standby state. Four moisturizing caps 6, 6,... Are provided. These four moisturizing caps 6, 6, ... correspond to the arrangement of the inkjet heads 2, 2, ... so that the nozzle surfaces 15b, 15b, ... of the four inkjet heads 2, 2, ... can be covered simultaneously. Arranged.
[0021]
The control unit includes a CPU (Central Processing Unit) and a memory, and controls each component of the inkjet printer 1. The memory stores image data to be formed on the recording medium 13 and a program for controlling each component of the inkjet printer 1. The CPU performs an operation based on image data or a program stored in the memory, and transmits a control signal to each component based on the operation result.
[0022]
Next, the inkjet head 2 according to the present invention will be described with reference to FIGS.
2 and 3 are exploded perspective views of the inkjet head 2 of the present embodiment. 2 and 3 are drawn from different directions (almost 180 degrees different).
The inkjet head 2 according to the present embodiment includes a housing frame 14, an inkjet head chip (hereinafter simply referred to as “head chip”) 15, two manifolds 16a and 16b, a cap receiving plate 17, and two flexible wiring boards. 18a, 18b, two drive circuit boards 19a, 19b, an external connector 21, a wiring support plate 22, a flexible wiring board 23, and a cover 24.
A number of nozzles are continuously provided in the direction of arrow E at the end 15 a of the head chip 15. Specifically, a nozzle (nozzle plate) made of metal, resin, or the like in which nozzle-shaped holes are processed is attached to the end surface of the end portion 15a where the pressurizing chamber outlet is provided. Is provided. As a result, the nozzle outlet is disposed on the nozzle surface 15b. A row of nozzles provided continuously in the direction of arrow E is referred to as a nozzle row. The inkjet head 2 has two nozzle rows. The outlets of these nozzles become ink discharge ports. The head chip 15 has a long outer shape in the direction of arrow E. The inkjet head 2 is mounted on the carriage 3 so that the arrow E direction and the main scanning direction A shown in FIG.
[0023]
The head chip 15 is a device that ejects ink filled in an ink flow path (pressure chamber) formed therein from a nozzle. An ink flow path (pressure chamber) provided with a piezoelectric element that generates pressure (ejection force) for ejecting ink from the nozzle in front of the nozzle at the end 15a of the head chip 15 corresponds to each nozzle. Is formed. The discharge force may be generated by other means such as a heater element. A piezoelectric element that gives ejection force to each nozzle in one nozzle row is driven by a drive circuit mounted on the drive circuit board 19a, and a piezoelectric element that gives ejection force to each nozzle in the other nozzle row is mounted on the drive circuit board 19b. It is driven by the drive circuit. For this purpose, the drive circuit boards 19a and 19b are connected to both side surfaces of the head chip 15 via flexible wiring boards 18a and 18b, respectively.
Electrical connection between the drive circuit boards 19a and 19b and the outside is performed by the external connector 21, the flexible wiring board 23, and the internal connectors 20a and 20b. The internal connectors 20a and 20b are mounted on the drive circuit boards 19a and 19b, respectively. An external electrode of the flexible wiring board 23 is connected to the external connector 21, and one end of the flexible wiring board 23 including the external electrode is attached to and supported on the wiring support plate 22. The other end portion of the flexible wiring board 23 is extended from the wiring support plate 22 so as to be divided into two, and an internal electrode is formed at the tip thereof. These internal electrodes are connected to the internal connectors 20a and 20b. When the inkjet head 2 is mounted, the external connector 21 is connected to a connector installed on the carriage 3.
[0024]
Manifolds 16a and 16b are attached to both side surfaces of the head chip 15, respectively. Filter installation portions a1 and a2 are provided on the side surfaces of the head chips 15 of the manifolds 16a and 16b. A filter a3 is attached to the filter installation part a1, and a filter a4 is attached to the filter installation part a2. Each filter a3, a4 is preferably attached to the corresponding filter installation part a1, a2 by thermocompression bonding or adhesion. Moreover, the filter installation part a1 is shown in FIG. 3, and the filter installation part a2 is shown in FIG.
The cap receiving plate 17 is attached to the manifolds 16a and 16b. At this time, the nozzle surface 15 b is exposed through the opening 17 a provided in the cap receiving plate 17.
Ink is supplied to the flow path connector 14p formed on the housing frame 14 from the ink supply pipe 26 shown in FIG. An ink flow path is continuously formed in the flow path connector 14p and the flow path forming portion 14n, and this ink flow path is connected to the ink flow path formed in each of the manifolds 16a and 16b. The ink that reaches the manifolds 16a and 16b passes through the filters a3 and a4, and is further introduced into an ink flow path (pressure chamber) formed in the head chip 15.
The cap receiving plate 17 receives the suction cap 8 and the moisture retaining cap 6 and is in close contact with them.
[0025]
The housing frame 14 includes a base frame portion 14a that houses the head chip 15, the manifolds 16a and 16b, and the cap receiving plate 17, and side wall portions 14g and 14h that are erected from both longitudinal ends of the base frame portion 14a. And a heat sink 14k and a connector support portion 14m formed so as to span the both side wall portions 14g and 14h, and head chip holding portions 14i and 14j formed inside the both side wall portions 14g and 14h, respectively.
Both end portions of the head chip 15 are held by the head chip holding portions 14i and 14j, respectively. The head chip 15, the two manifolds 16a and 16b, the cap receiving plate 17 and the base end frame portion 14a are fixed to each other by an adhesive.
The drive circuit boards 19a and 19b are joined to the heat sink 14k. The connector support portion 14m supports the external connector 21.
A cover 24 is attached to the housing frame 14, and four side surfaces and an upper end surface (= surface opposite to the nozzle surface 15b) of the head housing are configured. A connector holding opening 24a is formed on the end surface of the cover 24 constituting the upper end surface of the head casing. When the cover 24 is attached to the housing frame 14, the external connector 21 and the wiring support plate 22 are held by the connector holding opening 24a.
In addition, three fulcrum contact portions 14b, 14c, and 14d and two bolt insertion portions 14e and 14f are attached to the outer periphery of the base end frame portion 14a. The three fulcrum contact portions 14b, 14c, and 14d are portions that are supported by being in contact with the three fulcrums on the carriage 3 side when the inkjet head 2 is positioned on the carriage 3. After positioning, bolts for fixing the inkjet head 2 to the carriage 3 are inserted into bolt insertion holes formed in the bolt insertion portions 14e and 14f.
[0026]
Next, the inkjet head chip (head chip) 15, the manifolds 16a and 16b, and the housing frame 14 will be described in more detail with reference to FIGS.
[0027]
In this embodiment, as described above, the head chip 15 has two nozzle rows that are continuously provided in the direction of arrow E in FIG. 2, and a drive circuit board is provided for each nozzle row. Have. For this reason, in this embodiment, the head chip 15 is provided with two drive circuit boards 19a and 19b, and the upper end (electrodes 15c and 15d) of the head chip 15 and the lower end of the drive circuit board are connected. There are also two flexible wiring boards (FPCs) (reference numerals 18a and 18b). Here, the piezoelectric element of the head chip 15 is made of PZT (lead zirconate titanate).
[0028]
The manifold is composed of two members 16a and 16b, which are engaged with each other with the head chip 15 interposed therebetween, and are fixedly bonded. In this embodiment, engagement pieces 16g and 16h are provided at both ends of the member 16a in the nozzle juxtaposition direction, and the engagement pieces 16g and 16h protrude to a predetermined position of the member 16b, here, inside the manifold. The protruding pieces 16v and 16w are engaged with the outer positions. Thus, the inkjet head chip 15 is also held and fixed from both ends in the nozzle juxtaposition direction. The ink jet head chip 15 and the manifold members 16a and 16b are bonded and fixed so that ink in the manifold does not leak out.
[0029]
Further, the manifolds 16a and 16b are bonded and fixed to the housing frame 14 at least at two locations close to both ends in the nozzle juxtaposition direction. In this embodiment, the housing frame 14 is made of a metal, and in this example, is made of an aluminum molded product. By adhering a resin manifold (high thermal expansion coefficient) to a metal housing frame (low thermal expansion coefficient than resin), the opposite action is exerted against expansion and contraction of the manifold due to temperature changes. be able to. In addition, here, the manifold recess 16t is engaged and fixed at a predetermined position of the casing frame, and the planar portion 16s is brought into contact and fixed to be fixed to the casing frame. ing. In this way, the expansion and contraction of the manifold can be suppressed as much as possible by adhering to the housing frame at the portions near the both ends of the nozzle in the side-by-side direction. Furthermore, if the location where the manifold is bonded to the housing frame is close to or close to the top surface of the manifold, it is more effective in preventing damage to the electrodes 15c and 15d of the inkjet head chip 15.
[0030]
As described above, according to the ink jet head chip in this embodiment, the members constituting the manifold are bonded and fixed to the housing frame at least at two locations close to both ends in the nozzle juxtaposition direction. Is bonded to a housing frame having a low coefficient of thermal expansion to suppress expansion and contraction of the manifold, and can prevent damage to the manifold and electrodes of the inkjet head chip.
[0031]
Further, in this embodiment, since the manifold is provided with an engagement portion that clamps and fixes the inkjet head chip from both ends in the nozzle juxtaposition direction, the engagement portion is used when the manifold is contracted at a low temperature. As a result, it is possible to prevent the manifold and the electrodes of the inkjet head chip from being damaged due to the contraction of the manifold.
[0032]
The ink jet head and the ink jet printer according to the present invention are not limited to the above-described embodiments, and can be applied to other configurations. For example, the ink jet head is not limited to a configuration including a piezoelectric element in a head chip, and may be configured to include a heater, for example.
[0033]
In this embodiment, the manifold is bonded and fixed to the housing frame at two bonding locations. However, the manifold is not limited to this and may be bonded and fixed at three or more multiple locations. In this case as well, two points close to both ends in the nozzle juxtaposition direction are included as the bonding points.
[0034]
【The invention's effect】
According to the first aspect of the present invention, the members constituting the manifold are bonded and fixed to the housing frame having a lower coefficient of thermal expansion than that of the manifold at least at two locations near both ends in the nozzle juxtaposition direction. It is bonded to a housing frame that has a lower thermal expansion coefficient than the manifold, so that expansion and contraction of the manifold can be suppressed, and damage to the manifold and ink jet head chip electrodes can be prevented.
[0035]
According to the second aspect of the present invention, the manifold is provided with the engaging portion that clamps and fixes the ink jet head chip from both ends in the nozzle juxtaposed direction. The inkjet head chip sandwiched by the engaging portion prevents the contraction, and as a result, it is possible to prevent the manifold from being damaged and the electrodes of the inkjet head chip from being damaged by the contraction of the manifold.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing an ink jet printer according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view of an inkjet head according to an embodiment of the present invention.
3 is an exploded perspective view illustrating an inkjet head according to an embodiment of the present invention, viewed from a direction different from that of FIG. 2 by approximately 180 degrees.
FIG. 4 is an enlarged exploded perspective view including an inkjet head chip and a manifold constituting an inkjet head according to an embodiment of the present invention.
FIG. 5 is an enlarged perspective view of a state in which the members of FIG. 4 are assembled.
FIG. 6 is an enlarged perspective view showing one side of a manifold constituting the ink jet head according to the embodiment of the present invention.
FIG. 7 is an enlarged perspective view showing the other side of the manifold constituting the ink jet head according to the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inkjet printer 2 Inkjet head 3 Carriage 4 Carriage rail 5 Moisturizing unit 6 Moisturizing cap 7 Maintenance unit 8 Suction cap 9 Suction pump 10 Waste ink tank 11 Cleaning blade 12 Ink receiver 13 Recording medium 14 Housing frame 14a Base frame part 14b , 14c, 14d, fulcrum contact portions 14e, 14f, bolt insertion portions 14g, 14h, side wall portions 14i, 14j, head chip holding portions 14k, heat radiating plates 14m, connector support portions 14n, flow path forming portions 14p, flow path connectors 15, head chips (inkjet head chips).
15a End 15b Nozzle surface (tip surface)
16a, 16b Manifold 17 Cap receiving plate 17a Openings 18a, 18b Flexible wiring boards 19a, 19b Drive circuit boards 20a, 20b Internal connector 21 External connector 22 Wiring support plate 23 Flexible wiring board 24 Cover 24a Connector holding opening 25 Ink tank 26 Ink Supply pipe A Main scanning direction B Home position area C Recording area D Maintenance area

Claims (2)

An inkjet head chip in which nozzles for ejecting ink are arranged in parallel;
A manifold that is adhesively fixed to a side portion of the inkjet head chip and guides ink to the inkjet head chip;
A housing frame for housing the manifold;
An inkjet head comprising:
The manifold is composed of two members having a higher coefficient of thermal expansion than the inkjet head chip , and at least two positions near the both ends in the nozzle juxtaposition direction on each member of the manifold. is bonded and fixed,
The inkjet head according to claim 1, wherein the housing frame has a coefficient of thermal expansion higher than that of the inkjet head chip and lower than that of the manifold .   The inkjet head according to claim 1, wherein an engagement portion is provided at both ends of the manifold in the nozzle juxtaposition direction to sandwich and fix the inkjet head chip from the both ends.

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