JP2007331242A - Inkjet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To ensure an efficient restoration by adjusting the suction force in a cap suction operation for a bubble or highly-viscous ink blocked in the shape of a solid which are generated near a recording head nozzle. <P>SOLUTION: In an inkjet recording device, the cross-sectional area of a part of a channel formed in caps 209 to 212 is made smaller than the ones of other channels so as to get the same effect as an ejector mechanism, and negative pressure is generated by pouring ink in the caps 209 to 212, then the recording head is restored. The flow of the ink supplied in the cap is controlled by a pump 401, then the suction force generated in the cap is controlled. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to an ink jet recording apparatus having a recovery mechanism that maintains normal performance of a recording head.

When the recording head of an ink jet recording apparatus performs a continuous recording operation, there is a concern that ink droplets adhere to, grow and thicken in the vicinity of a plurality of recording head nozzles that eject ink, and that normal ink ejection performance may be hindered. is there.

Therefore, conventionally, in such an ink jet recording apparatus, a method in which a suction pump is operated to generate a negative pressure in the cap while the cap is in close contact with the recording head, and ink is sucked from the recording head nozzle (suction recovery). Alternatively, a method of discharging ink from the print head nozzles using a pressure pump (pressure recovery) is used.

However, when performing suction recovery, since suction is performed from the nozzles of all the recording heads, the flow resistance of the nozzles that first eliminated the nozzle clogging is reduced, and the suction force for sucking the other nozzles is reduced. It is hard to say that the nozzle is fully recovered.

  In addition, as the recording head becomes longer, there is a concern that the pressure generated by suction varies depending on the location, and thus unevenness occurs in recovery.

  Similarly, in the case of pressure recovery, there is a possibility of unevenness in recovery due to non-uniform pressure.

  According to a first aspect of the present invention, a recording head for recording on a recording medium, an ink tank for supplying ink to the recording head, and a pump for supplying ink to the recording head are provided. In an ink jet recording apparatus comprising: a sub ink tank provided with a recycling mechanism that collects discharged ink and returns it to the ink tank; a control unit that controls an ink supply operation; and a cap that covers a discharge port of the recording head. In order to achieve the same effect as the ejector mechanism, a part of the flow path formed in the cap has a smaller cross-sectional area than the other flow paths, and negative pressure is generated by flowing ink into the cap. An ink jet recording apparatus for recovering the recording head.

  According to a second aspect of the invention, in the ink jet recording apparatus of the first aspect, the flow path formed in the cap is substantially parallel to the recording head nozzle row.

  According to a third aspect of the present invention, in the ink jet recording apparatus according to the first aspect, the flow path formed in the cap is substantially perpendicular to the recording head nozzle row.

  According to a fourth aspect of the present invention, in the ink jet recording apparatus of the first, second, or third aspect, the flow rate of the ink supplied into the cap is controlled by the pump, and the suction force generated in the cap is controlled. It is characterized by.

  According to a fifth aspect of the present invention, in the ink jet recording apparatus according to the first, second, or fourth aspect, the cap is provided with a groove that is substantially parallel to the nozzle array arranged in the recording head, and the groove is provided during a cap operation. Covers the nozzle row.

As described above, according to the present invention, the efficiency is improved by adjusting the suction force that is sucked in the cap suction operation with respect to bubbles generated near the recording head nozzle or thick ink clogged in a solid state. Recovery can be performed.

  Further, in the present invention, the ink used for printing is used as the fluid that generates the suction force, and the ink can be reused, thereby preventing the addition of a new pump and the waste of ink. I can do it.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing the overall configuration of an inkjet recording apparatus 101 applied in the present invention.

In the inkjet recording apparatus shown in FIG. 1, for example, a label sheet 102 wound in a roll shape and temporarily attached with a plurality of labels is supplied to the inkjet recording apparatus main body, and is imaged at a constant speed by a conveyor belt 104 driven by a conveyor motor 103. It is conveyed to the forming part.

Here, the image forming units are juxtaposed in the transport direction indicated by the arrows, and in a direction orthogonal to the transport direction, a large number of inkjet recording heads 105 and labels having a length substantially equal to the image formation width of the label paper 102 A transport belt 104 is provided for placing the sheet transported by the feeding device and passing under the ink jet recording head.

Each label leading edge of the label paper is detected by the leading edge detection sensor 106, and ink is ejected from the ejection port of the inkjet recording head 105 when each label passes below the plurality of inkjet recording heads 105 based on the detected position. Then, an image is formed on the label and recording is completed.

The recording is performed in color using inks corresponding to a total of four colors, for example, inkjet recording head black 105K, cyan 105C, magenta 105M, and yellow 105Y.
The ink jet recording head 105 is an ink jet recording unit that discharges ink using thermal energy, and includes an electrothermal transducer to generate thermal energy.

Recording is performed by ejecting ink from the ejection port using a pressure change caused by bubble growth and contraction caused by film boiling caused by thermal energy applied by the electrothermal transducer.

In addition, an ink tank 107 capable of storing ink is provided above each inkjet recording head 105, and ink is automatically supplied from the ink tank 107 to the inkjet recording head 105 when the ink is ejected from the ejection port. It has come to be.

  Next, the recovery mechanism 109 for cleaning the recording head 105 provided in the ink jet recording apparatus 101 will be described.

The recovery mechanism 109 is disposed under the ink jet recording head 105 during standby of the ink jet recording apparatus.

Also, when forming an image, the recovery mechanism 109 moves in the direction of the arrow (right side), the inkjet recording head 105 descends downward and discharges it to the label paper 102 conveyed by the paper supply unit 106, Form an image.

When performing a recovery operation for cleaning the inkjet recording head 105, the inkjet recording head 105 stops at the top of the recovery mechanism 109, and then the recovery mechanism cleans the inkjet recording head 105 at a constant speed in the direction of the arrow (right side). Moving. The position of the ink jet recording head 105 is moved to each position and stopped by a control system signal.

An ink tank 114 is provided independently for each color ink jet recording head 105 to fill each ink jet recording head 105 with ink.

Further, a supply mechanism (not shown) is provided, and an independent ink tank 114 is connected to the independent ink jet recording head 105, and ink is filled and supplied from the ink tank 114 to the ink jet recording head 105.

Next, the recovery mechanism 109 will be described in detail with reference to FIG. FIG. 2-1 shows the case where the ink jet recording head is at the cap position.

201 to 204 are wiper blades, and 205 to 208 are blade holders for holding the wiper blades. Reference numeral 213 denotes a recovery rod, and the blade holders 205 to 208 are slidable up and down. The ink jet recording head 105 is fixed to the head holder 214.

Reference numerals 209 to 212 denote recovery caps, which are provided in the recovery rod 213. The recovery caps 209 to 212 provided in the recovery bowl 213 have a hole in the lower part, and are configured to communicate with each other in the recovery bowl. The ink discharged from the ink jet recording head 105 is flowed to the recovery bowl 213. It is configured. The recovery caps 209 to 212 are elastic members. When the respective ink jet recording heads 105 are lowered and come into contact with the recovery caps 209 to 212, the inside of the recovery cap 213 is sealed.

Further, a groove 302 is formed in the recovery cap in the same direction as the recording head nozzle 301 row, and the groove 302 and the nozzle face each other in close contact during the cap operation.

FIG. 3 is a cross-sectional view of the recovery caps 209-212. The recovery caps 209 to 212 are formed in an ejector structure.

FIG. 4 is a flow chart of ink in this embodiment. Ink is supplied from the pump 401 to the recovery caps 209 to 212 as a working fluid.

The recovery caps 209 to 212 have a structure in which the ink supply side and the discharge side are communicated with each other, and the cross-sectional area in the vicinity of the upstream side (ejection part) of the part that contacts the recording head nozzle is significantly narrower than the other parts. Yes. The ink supplied from the pump flows into the diffusion chamber 110 at a speed at which the ink flows rapidly at the ejecting portion.

Due to the high-speed flow of the ink, the pressure in the diffusion chamber 110 decreases. Due to this pressure drop, the ink near the nozzle is sucked and sent to the sub tank 402 through the cap together with the ink used as the working fluid.

At this time, the working fluid is supplied in a direction substantially perpendicular to the recording head nozzle row, and suction is performed by generating a negative pressure uniformly in the vicinity of the recording head nozzles.

In addition, the valve 501 is opened, the valve 502 is closed, and the flow rate of the pump that supplies the working fluid is made variable, so that the amount of working fluid (ink) that passes through the ejection portion changes, and therefore, is generated in the diffusion chamber 110 The amount of pressure drop can also be adjusted. Therefore, when strong recovery is required, the flow rate of ink supplied from the pump is increased, and the amount of pressure drop generated in the diffusion chamber 110 is increased.

  Further, the ink used for the recovery operation is returned to the sub tank again by the pump as described above, and is used again during the subsequent recovery operation or returned to the ink tank 403 provided on the upper part of the recording head. After that, it is supplied to the recording head and can be used for printing.

  FIG. 5 is a cross-sectional view of the recovery cap in this example. Similar to the first embodiment, the ejector mechanism is provided.

The working fluid is supplied in a direction substantially parallel to the recording head nozzle row.
The part having the ejector structure and the part having the role of the recovery cap are communicated with each other through a communication hole provided in the diffusion chamber 110, and the negative pressure generated in the diffusion chamber 110 passes through the communication hole to make the pressure inside the recovery cap negative. Ink is sucked from the recording head nozzle.

  FIG. 6 is a diagram showing a case where a sub tank for supplying ink to each recording head is provided below the recording head in the embodiment shown in Example 1 or Example 2. In this case, the supply of ink to the recording head and the control of the pressure in the recording head are controlled by the height (water head difference) between the recording head nozzle surface and the liquid level in the sub tank.

Further, the ink used for the recovery operation is returned to the sub-tank by the pump again, and is used again during the subsequent recovery operation or supplied to the recording head.
It can be used for printing.

FIG. 7 shows an electrical block diagram of the ink jet recording apparatus embodying the above invention.

The host computer 701 transfers recording data used for the ink jet recording apparatus to the interface controller 702 of the ink jet recording apparatus 101 and instructs recording. In addition, a command for instructing the number of recording media to be recorded and the type and size of the recording media can be transferred to the interface controller 702 and designated.

A CPU (Central Processing Unit) 703 is an arithmetic processing unit that performs overall control of recording data reception, recording operation, recording medium handling, etc., based on a control program that executes procedures stored in the ROM 704. Execute.

After analyzing the command, the CPU 703 instructs the interface controller 702 to develop the image data of each color component of the recording data on the image ROM 705 as a bitmap.

As an operation process before recording, the CPU 703 includes an I / O (input / output port) 708, a capping motor 711 that moves the cleaning mechanism via the motor driving unit 713, and a head motor 715 that moves the inkjet recording head 105 up and down. And the inkjet recording head 105 is moved from the standby position to the recording position.

The transport unit is driven by the transport motor 710, and the continuous transport operation of the label paper 102 is started.

In order to determine the recording timing of the label sheet 102 conveyed at a constant speed, the leading end position of the sheet is detected by a sheet leading end detection sensor 714 disposed on the upstream side of the recording head. In synchronization with paper conveyance, the recording head control circuit 712 sequentially reads the corresponding color image data from the image ROM 705, transfers the data to the ink jet recording head 105 that discharges the corresponding color ink, and performs color printing.

The operation panel 709 is a portion for displaying a warning such as no ink and performing an operation such as a reset. The operation of the CPU 703 is executed based on the processing program stored in the program ROM 704, and uses the work RAM 706 as a working memory.
The EEPROM 707 is a non-volatile memory and stores apparatus-specific parameters such as a minute recording position adjustment value between recording heads.

1 is a schematic view showing a standby state of an ink jet recording apparatus embodying the present invention. 1 is a schematic view showing a recovery mechanism of an ink jet recording apparatus embodying the present invention. FIG. 3 is a cross-sectional view of the recovery cap of the first implementation system implemented according to the present invention. FIG. 4 is a diagram showing an ink flow path of a first implementation system implemented in the present invention. FIG. 4 is a cross-sectional view of a recovery cap of a second implementation system implemented according to the present invention. FIG. 5 is a diagram showing an ink flow path of a third implementation system implemented in the present invention. 1 is an electrical block diagram of an ink jet recording apparatus embodying the present invention.

Explanation of symbols

101 Inkjet recording device
102 Label paper
103 Conveyor motor
104 Conveyor belt
105 Inkjet recording head
106 Tip detection sensor
107 Diffusion chamber of ink tank recovery mechanism
201-204 Wiper blade
205-208 Blade holder
209 to 212 Recovery cap Recovery 桶 Head holder Recording head nozzle row groove
401 Pressure pump
402 Sub tank ink tank
501,502 valves

Claims (5)

  A recording head for recording on a recording medium, an ink tank for supplying ink to the recording head, and a pump for supplying ink to the recording head, and recovering ink discharged from the recording head during a recovery operation The same effect as the ejector mechanism in an ink jet recording apparatus including a sub ink tank provided with a recycling mechanism for returning to the ink tank, a control unit that controls the ink supply operation, and a cap that covers the ejection port of the recording head So that a part of the flow path formed in the cap has a smaller cross-sectional area than the other flow paths, and a negative pressure is generated by flowing ink into the cap to recover the recording head. An ink jet recording apparatus.   2. The ink jet recording apparatus according to claim 1, wherein the flow path formed in the cap is substantially parallel to the recording head nozzle row. 2. The ink jet recording apparatus according to claim 1, wherein the flow path formed in the cap is substantially perpendicular to the recording head nozzle row.   4. The ink jet recording apparatus according to claim 1, wherein a flow rate of ink supplied into the cap is controlled by the pump to control a suction force generated in the cap. 5. The ink jet recording apparatus according to claim 4, wherein the cap is provided with a substantially parallel groove facing the nozzle array arranged in the recording head, and the groove covers the nozzle array during a cap operation.

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