JP2007125775A - Inkjet head and inkjet type recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet head which can facilitate discharge of bubbles by preventing the bubbles from being large, and to provide an inkjet type recorder. <P>SOLUTION: An electric heater 61 is set in the periphery of a filter chamber 32a of an ink supply needle 31. An outer wall of the filter chamber 32a is heated, so that a passage of the ink supply needle 31, particularly, an inner wall of the filter chamber 32a is heated. Thus a volume of the bubbles adhered to the inner wall is expanded. The bubbles are facilitated to separate from a wall surface and prevented from being large. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet head and an ink jet recording apparatus that are used in an ink jet recording head and include a filter for removing foreign matters, bubbles, and the like in ink.

  In general, in an ink jet recording head, ink is supplied from an ink cartridge filled with ink through an ink supply needle and a flow path inserted into the ink cartridge, and the supplied ink drives a piezoelectric element or the like. Is discharged from the nozzle.

  Such an ink jet recording head has a problem of causing ejection failure when air bubbles present in the ink of the ink cartridge or air bubbles mixed in the ink when the ink cartridge is attached or detached are supplied. Similarly, there is a problem that a foreign matter existing in the ink causes a discharge failure. For this reason, the ink flow path between the normal ink cartridge and the ink jet recording head is provided with a plurality of fine holes and a filter for removing bubbles in the ink.

  As this filter, for example, as described in Patent Document 1 below, a filter or the like woven with fibers and having a filter hole is used, and foreign matter and bubbles are trapped when ink passes through the filter. The Further, the bubbles trapped in the filter in this manner are discharged from the nozzle openings during the head cleaning operation. Specifically, by sucking ink from the nozzle opening and generating a flow rate faster than that generated during normal ink ejection, bubbles are discharged from the nozzle opening through the filter.

  However, if a flow rate faster than normal ink ejection is generated during cleaning, the amount of ink consumed increases, resulting in a problem that the amount of ink used for actual printing decreases. Further, in order to increase the flow rate of ink, it is necessary to increase the size of a pump for sucking ink, and there is a problem that the size of the head must be increased.

Japanese Patent Laid-Open No. 11-10904

  The present invention has been made in view of the above situation, and an object thereof is to provide an ink jet head and an ink jet recording apparatus that can easily discharge bubbles while suppressing the enlargement of bubbles.

In order to achieve the above object, a first aspect of the present invention includes a recording head body having a plurality of nozzle openings for discharging ink droplets, and an ink supply that communicates with the ink cartridge and supplies ink in the ink cartridge to the recording head. Means, an ink flow path communicating with the recording head main body and the ink supply means, a filter provided between the ink flow path and the ink supply means, and heating the vicinity of the filter to suppress the adhesion of bubbles to the wall surface of the flow path. And an ink jet head characterized by comprising a heating means.
In the first aspect, the vicinity of the filter is heated by the heating means, thereby suppressing the bubble from adhering to the wall surface of the flow path to suppress the bubble from becoming large and easily discharging the bubbles without increasing the suction force or the like. To do.

According to a second aspect of the present invention, in the ink ejecting head according to the first aspect, the ink supply means is a hollow ink supply needle whose tip is inserted into the ink cartridge, and a root portion of the ink supply needle. Is communicated with the ink flow path through a filter.
In the second aspect, the channel wall surface of the root portion of the ink supply needle can be heated.

According to a third aspect of the present invention, in the ink ejecting head according to the second aspect, the heating means is provided on the outer periphery of the ink flow path and heats the outer wall of the ink flow path. Located in the ink jet head.
In the third aspect, the outer wall of the ink flow path can be heated to raise the temperature of the inner wall, thereby suppressing bubble adhesion.

According to a fourth aspect of the present invention, in the ink ejecting head according to the third aspect, the ink flow path is a root portion of the ink supply needle, and the heating means heats the outer wall of the root portion. An ink jet head characterized by the above.
In the fourth aspect, the outer wall of the base portion of the ink supply needle can be heated to raise the temperature of the inner wall, thereby suppressing bubble adhesion.

According to a fifth aspect of the present invention, in the ink ejecting head according to the second aspect, the heating means is provided in the ink flow path and heats the inner wall of the flow path and the ink. Located in the ink jet head.
In the fifth aspect, the inner wall of the flow channel and the ink can be heated to suppress the adhesion of bubbles.

According to a sixth aspect of the present invention, in the ink ejecting head according to any one of the first to fifth aspects, the heating unit is an electric heater.
In the sixth aspect, the flow path can be heated by the electric heater.
As another aspect of the heating source, in addition to the electric heater, heat radiated from a drive actuator of a device on which the ink ejection head is mounted can be used as the heating source.

In order to achieve the above object, a seventh aspect of the present invention is an ink jet recording apparatus characterized in that the ink jet head according to any one of the first to sixth aspects is mounted on a carriage.
In the seventh aspect, an ink ejection head that suppresses the bubble from adhering to the channel wall surface and suppresses the bubble from being enlarged, and can easily discharge the bubble without increasing the suction force is mounted. An ink jet recording apparatus can be obtained.

  FIG. 1 is a schematic configuration of an ink jet recording apparatus including an ink jet head according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of the main part of the ink jet head, and FIG. FIG. 4 shows the appearance of the ink supply needle, and FIG. 5 shows the cross section of the ink supply needle (details of the main part of FIG. 3).

  An ink jet recording apparatus (apparatus main body) 1 includes an ink ejection head 5 in which a carriage 3 on which an ink cartridge 2 is mounted, a recording head 4 attached to the carriage 3, and the like are integrated. The carriage 3 is connected to a stepping motor 7 via a timing belt 6 and is guided by a guide bar 8 to reciprocate in the paper width direction (main scanning direction) of the recording paper 9. The carriage 3 has a box shape that opens to the top, and is attached so that the nozzle surface of the recording head 4 is exposed on the surface (lower surface) facing the recording paper 9 and accommodates the ink cartridge 2.

  Ink is supplied from the ink cartridge 2 to the recording head 4, and ink droplets are ejected onto the upper surface of the recording paper 9 while moving the carriage 3 to print images and characters on the recording paper 9 in a dot matrix. . In FIG. 1, reference numeral 10 denotes a cap that prevents the nozzle from drying by sealing the nozzle opening of the recording head 4 during a printing pause and performs a cleaning operation by applying a negative pressure to the nozzle surface of the recording head 4. 11 is a wiper blade for wiping the nozzle surface of the recording head 4, 12 is a waste ink storage unit for storing the waste ink sucked by the cleaning operation, and 13 is a control device for controlling the operation of the apparatus main body 1. It is.

  As shown in FIG. 2, the ink ejecting head 5 (see FIG. 1) is provided with a control board 15, and an operation signal from the control device 13 (see FIG. 1) is transmitted via the control board 15 to a piezoelectric vibrator 16 described later. To enter. The control board 15 is arranged along the portion of the head case 18 opposite to the flow path unit 17, that is, along the upper surface of the head case 18.

The structure of the recording head 4 will be described with reference to FIG.
A flow path unit 17 is disposed at the tip of the recording head 4, and the flow path unit 17 is provided with a nozzle plate 19 in which nozzle openings 20 are arranged on a nozzle forming surface 19 a. A pressure generation chamber 21 that communicates with the nozzle opening 20 and pressurizes ink by the piezoelectric vibrator 16 is provided, and ink is supplied to the pressure generation chamber 21 from the ink storage chamber 22.

  That is, the flow path unit 17 includes a nozzle plate 19 having a nozzle forming surface 19 a in which the nozzle openings 20 are formed, an ink storage chamber 22 that is a common liquid storage chamber with the pressure generation chamber 21, and ink that communicates these. A pressure generation chamber forming plate 24 in which a space corresponding to the supply path 23 is formed, and a sealing plate for sealing the opening of the pressure generation chamber 21 and the ink storage chamber 22, that is, a vibration plate 25 are laminated. . The nozzle forming surface 19a is a flat surface. The flow path unit 17 is joined to the front end surface 18a of the head case 18 using an adhesive.

  The piezoelectric vibrator 16 is a so-called longitudinal vibration mode vibrator that contracts in the longitudinal direction in a charged state in response to the input of a drive signal and expands in the longitudinal direction in the process of discharging from the charged state. The other end of the piezoelectric vibrator 16 is fixed to the base 26 with its tip fixed to an island 25 a of a diaphragm 25 that forms a part of the pressure generating chamber 21. The longitudinal vibration mode piezoelectric vibrator 16 may be changed to a flexural vibration mode piezoelectric vibrator.

  A head flow path 27 is formed in the head case 18 at a portion corresponding to the ink storage chamber 22, and the ink of the ink cartridge 2 (see FIG. 1) is introduced into the ink storage chamber 22 through the head flow path 27. A flexible circuit board 28 is connected to the piezoelectric vibrator 16 and a drive signal from the control board 15 is input. A flexible circuit board 29 that sends an operation signal from the control device 13 (see FIG. 1) that operates the entire apparatus main body 1 (see FIG. 1) to the control board 15 is connected to the control board 15 via a terminal 30. ing.

  In the recording head 4, the pressure generating chamber 21 expands and expands in response to the contraction / extension of the piezoelectric vibrator 16, and ink suction and ink droplet ejection are performed by pressure fluctuations in the pressure generating chamber 21. The nozzle plate 19 has a pair of two nozzle rows, and a plurality of pairs are formed. A head cover 14 that protects the nozzle forming surface 19a is provided, and when the nozzle forming surface 19a is wiped, the wiper blade 11 (see FIG. 1) rubs against the corner of the flow channel unit 17 and does not operate smoothly. The head cover 14 prevents the corners of the head from being damaged.

  The ink sent from the ink cartridge (see FIG. 1) flows into the ink storage chamber 22 from the head flow path 27, and then is pressurized by the operation of the piezoelectric vibrator 16 in the pressure generation chamber 21, and is discharged from the nozzle opening 20. Printing proceeds by being ejected in the form of ink droplets toward the recording paper 9 (see FIG. 1).

  The configuration of the recording head 4 is not limited to the configuration in the illustrated example, and an elastic film is provided on the flow path forming substrate in which the pressure generating chamber is formed, and the elastic film is deformed by driving the piezoelectric element to drop ink droplets. It is also possible to apply a configuration for discharging from a nozzle.

The overall configuration of the ink ejecting head 5 will be described with reference to FIG.
As shown in FIG. 3, the ink ejecting head 5 is configured with the recording head 4 coupled to a head holder 41 corresponding to the carriage 3 (see FIG. 1). A plate-like member 41a is disposed on the head holder 41, and an ink supply needle 31 that enters the ink cartridge 2 (see FIG. 1) is attached to the plate-like member 41a. The internal passage of the ink supply needle 31 communicates with the introduction flow path 33 through the filter 32, and the introduction flow path 33 is formed by an introduction pipe 34 provided below the plate-like member 41a. The filter 32 can trap bubbles and foreign matter in the ink.

  An annular protrusion 42 at the top of the head case 18 passes through the control board 15, and the head flow path 27 and the introduction flow path 33 are arranged coaxially. The head channel 27 and the introduction channel 33 are connected in a state of being sealed by a packing member 35, and the packing member 35 is made of an elastic material such as an elastomer. By attaching the head case 18 to the head holder 41 via the packing member 35, the packing member 35 is compressed between the end surface of the introduction tube 34 and the end surface of the annular protrusion 42. With such a flow path structure, when the ink supply needle 31 is relatively inserted into the ink cartridge 2 that is a fluid supply source, ink is supplied to the flow path unit 17.

  As shown in FIGS. 3 to 5, the vicinity of the end of the ink supply needle 31 on the filter 32 side is a hemispherical filter chamber 32 a (root portion) whose diameter gradually increases as it approaches the filter 32. The filter chamber 32a is a space for accumulating bubbles and the like trapped by the filter 32, and prevents the filter 32 from being blocked until a predetermined amount of bubbles is accumulated.

  On the other hand, an electric heater 61 as a heating means is provided on the outer periphery of the filter chamber 32a of the ink supply needle 31, and the electric heater 61 is energized at a predetermined time via, for example, the control board 15, and is attached to the outer wall of the filter chamber 32a. Is heated (eg, 50 ° C.). Heating the outer wall of the filter chamber 32a raises the temperature of the flow path of the ink supply needle 31, particularly the inner wall of the filter chamber 32a, and the volume of bubbles adhering to the inner wall expands. As a result, the surface tension of the ink is lowered, so that the bubbles are easily separated from the wall surface.

  By providing the electric heater 61 on the outer periphery of the filter chamber 32a, a heating means can be easily provided.

  In this way, the bubbles are separated from the wall surface before the bubbles become too large and the adhesion of the bubbles to the wall surface of the flow path is suppressed. In addition, the temperature of the ink is increased together with the inner wall of the filter chamber 32a, and the viscosity of the ink is increased. Therefore, the loss resistance when the ink passes through the filter also decreases. Therefore, since the ink flow rate can be increased without increasing the suction force, the bubbles away from the wall surface can be easily discharged.

  In addition, since the force required to break up the bubbles decreases due to a decrease in the surface tension of the ink due to the temperature rise of the ink, the flow rate required for the bubbles to pass through the filter decreases, and the bubbles can be discharged more easily. Can do.

  The part where the electric heater 61 as the heating means is provided can be provided on the outer periphery of the introduction flow path 33 as shown by the dotted line in FIG. It is also possible to provide an electric heater 61 on the inner wall of the filter chamber 32a to heat the inner wall and ink directly. Moreover, it is also possible to use a heating means using heat radiated from the stepping motor 7 (see FIG. 1) as a heating source. And it is also possible to apply metal resin with high heat conductivity as resin which constitutes ink supply needle 31 and head holder 41 (refer to Drawing 3).

  In the ink jet recording apparatus 1 described above, a head cleaning operation is performed at a predetermined timing. As this cleaning operation, a small amount of ink, for example, about 0.2 to 0.3 g of ink is sucked to eliminate or prevent clogging of the nozzle openings 20, and almost all of the ink flow path. Ink, for example, about 1 g of ink is sucked to prevent or prevent clogging of the nozzle openings 20 of the recording head 4, and bubbles trapped by the filter 32 are discharged to the outside to cause defective printing such as missing dots. Cleaning operation to eliminate or prevent the above.

  For example, during the latter cleaning operation, the electric heater 61 is energized to heat the outer wall of the filter chamber 32a. As a result, the temperature of the flow path of the ink supply needle 31, particularly the inner wall of the filter chamber 32a, is increased, and the volume of bubbles adhering to the inner wall expands and is easily separated from the wall surface. The bubble is separated from the wall surface and the bubble is prevented from adhering to the channel wall surface, and the bubble is prevented from being enlarged.

  Prior to the cleaning operation, the electric heater 61 is energized, and when it is detected that the electric heater 61 has been heated to a predetermined temperature, or when the heating is performed for a predetermined time, the cleaning operation can be started. Thereby, cleaning can be performed after air bubbles are reliably separated from the flow path wall surface.

  As a result, the bubbles are maintained as small bubbles that can pass through the filter 32, and the bubbles can be easily discharged without increasing the suction force or the like. In addition, the temperature of the ink is raised together with the inner wall of the filter chamber 32a, and the viscosity of the ink is lowered, so that the flow rate of the ink can be increased without increasing the suction force, and even large bubbles can be discharged. Further, when small bubbles are maintained, the bubbles can be discharged with a low suction force.

  Therefore, it is possible to provide an ink jet head and an ink jet recording apparatus that can suppress the enlargement of the bubbles and easily discharge the bubbles.

  INDUSTRIAL APPLICABILITY The present invention is used in an ink jet recording head and can be used in the technical field of an ink jet head and an ink jet recording apparatus provided with a filter for removing foreign matters, bubbles, and the like in ink.

1 is a schematic configuration diagram of an ink jet recording apparatus according to an embodiment. FIG. 3 is a cross-sectional view of a main part of the ink ejecting head. 2 is a cross-sectional view illustrating the entire ink ejecting head. FIG. It is an external view of an ink supply needle. It is sectional drawing of an ink supply needle | hook.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Inkjet recording device, 4 Recording head, 5 Ink jet head, 16 Piezoelectric vibrator, 17 Flow path unit, 19 Nozzle plate, 20 Nozzle opening, 23 Ink supply path, 31 Ink supply needle, 32 Filter, 61 Electric heater

Claims (7)

A recording head main body having a plurality of nozzle openings for discharging ink droplets;
Ink supply means for communicating with the ink cartridge and supplying ink in the ink cartridge to the recording head;
An ink flow path communicating with the recording head main body and the ink supply means;
A filter provided between the ink flow path and the ink supply means;
An ink ejecting head comprising: heating means for heating the vicinity of the filter and suppressing the adhesion of bubbles to the wall surface of the flow path. The ink jet head according to claim 1,
The ink supply means is a hollow ink supply needle whose tip is inserted into the ink cartridge, and the base of the ink supply needle communicates with the ink flow path through a filter. . The ink jet head according to claim 2, wherein
An ink ejecting head, wherein the heating means is provided on an outer periphery of the ink flow path and heats an outer wall of the ink flow path. The ink ejecting head according to claim 3.
An ink ejection head, wherein the ink flow path is a base portion of the ink supply needle, and the heating unit heats an outer wall of the base portion. The ink jet head according to claim 2, wherein
An ink ejecting head, wherein the heating means is provided in the ink flow path and heats the inner wall of the flow path and the ink. The ink jet head according to any one of claims 1 to 5,
An ink jet head characterized in that the heating means is an electric heater.   An ink jet recording apparatus comprising the ink jet head according to claim 1 mounted on a carriage.

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