JP2006327152A - Ink jet recording apparatus and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stabilize ink discharge in an ink jet recording apparatus. <P>SOLUTION: The apparatus is provided with a recording head 104 which discharges ink from discharge outlets, a sub tank 107 which retains ink to be supplied to the recording head 104, and a pump 211 which supplies the ink to the recording head 104 from the sub tank 107. When the recording head 104 discharges the supplied ink, the ink jet recording apparatus performs recording on a recording medium. A cap 410 covering the discharge outlets of the recording head 104, a pump 212 connected to the cap 410 and suctions the ink supplied to the recording head 104, and a cooling part 108 which cools the ink suctioned by the pump 212 are provided. The cooled ink in the cooling part 108 is returned to the sub tank 107. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus and a control method thereof.

  An ink jet recording apparatus (ink jet recording apparatus) has advantages that it generates less noise during recording and can record a high-resolution recording image at high speed by using a highly integrated head. ing.

  Here, in the case of an ink jet recording apparatus, the physical properties of the ink used are extremely important in order to constantly and stably eject ink (recording liquid) from the ejection port of the recording head. In particular, if the ink moisture evaporates and the ink viscosity increases, normal ink circulation cannot be performed during the recording head recovery operation, or normal ink droplets cannot be formed during ink ejection, and further normal operation to the recording head may occur. This is because it becomes difficult to perform refilling.

In order to solve such a problem, for example, in Japanese Patent Laid-Open Nos. 09-156124 and 10-278290, the moisture content of the ink is formed by forming pores between the cartridge or the ink tank and the atmosphere. It is supposed to suppress the evaporation of.
JP 09-156124 A JP-A-10-278290

  However, in the case of an industrial inkjet recording apparatus or the like, the amount of ink consumed is large, and the amount of ink that flows due to recording or the like is large. For this reason, there is a problem that air communication means such as pores have high resistance, it is difficult to appropriately maintain the pressure during ink flow, and stable ink ejection cannot be performed.

  On the other hand, if the diameter of the pores is increased so that the resistance is reduced to keep the pressure during ink flow adequately, the amount of water evaporation of the ink increases correspondingly, and the ink viscosity increases.

  The present invention has been made in view of the above problems, and an object thereof is to stabilize ink discharge in an ink jet recording apparatus.

In order to achieve the above object, an ink jet recording apparatus according to the present invention has the following configuration. That is,
An inkjet recording apparatus that performs recording on a recording medium by discharging ink supplied from a recording head,
A cap that covers the ejection port of the recording head;
A pump connected to the cap and sucking ink supplied to the recording head;
A cooling unit for cooling the ink sucked by the pump,
The ink cooled in the cooling unit is configured to be returned to the tank.

  According to the present invention, it is possible to stabilize ink ejection in an ink jet recording apparatus.

  Hereinafter, each embodiment of the present invention will be described with reference to the accompanying drawings.

[First embodiment]
<Device arrangement inside the inkjet recording apparatus>
FIG. 1 is a diagram showing an arrangement of devices inside the ink jet recording apparatus (100) according to the first embodiment of the present invention. In the figure, reference numeral 101 denotes a label sheet (recording medium) wound in a roll shape and temporarily attached with a plurality of labels, and is moved in the arrow “paper conveyance direction” in the figure by a conveyance belt 102 driven by a conveyance motor 103. It is transported at a constant speed.

  104K to 104Y are recording heads. When the leading end detection sensor 105 detects each label leading end of the label sheet 101, each recording head (104K to 104Y) records an image on each label at a predetermined recording timing based on the detected position.

  For image recording, for example, the recording head 104K (recording head for black ink), 104C (recording head for cyan ink), 104M (recording head for magenta ink), and 104Y (recording head for yellow ink), a total of four colors This is done in color using a recording head compatible with the above. Note that a line head having a recording width corresponding to the maximum width of a label to be used is used for each recording head (104K to 104Y) of the present embodiment.

  In the lower part of the ink jet recording apparatus 100, ink cartridges 106K to 106Y corresponding to the respective recording heads 104K to 104Y, sub tanks 107K to 107Y, and cooling traps 108K to 108Y are provided.

  In addition, capping mechanisms 109K to 109Y are provided below the recording heads 104K to 104Y corresponding to the respective recording heads. Although six capping mechanisms are illustrated in FIG. 1, this is a preliminary mechanism that assumes a case where, for example, light cyan, light magenta, or special color ink is added.

  Ink cartridges 106K to 106Y, sub tanks 107K to 107Y, recording heads 104K to 104Y, cooling traps 108K to 108Y, and capping mechanisms 109K to 109Y are connected by independent ink tubes for each ink (details will be described later). .

<Hardware configuration of inkjet recording apparatus>
Next, the hardware configuration of the inkjet recording apparatus 100 will be described with reference to FIG. Of the devices shown in FIG. 2, the devices corresponding to those in FIG. 1 are given the same reference numerals.

  Reference numeral 200 denotes a host computer, and the recording data transmitted from the host computer 200 is received by the interface controller 202 of the inkjet recording apparatus 100.

  In addition, the interface controller 202 receives data (for example, the number, type, size, and the like of labels) related to the label sheet 101 that is a recording medium for recording an image.

  A CPU (Central Processing Unit) 201 controls the overall inkjet recording apparatus 100 such as reception of recording data, image recording operation, and handling of a recording medium.

  The recording data received via the interface controller 202 is analyzed by the CPU 201 and then developed into the image memory 204 as image data for each color component.

  As an operation process before image recording, the CPU 201 mutually drives a capping motor (not shown) and a head motor (not shown) via an input / output port (I / O) 210 and a motor driving unit 211, and the recording heads 104K to 104K. 104Y is moved from the capping position (standby position) to the recording position (position of the recording head during image recording).

  Almost simultaneously, a paper feed motor (not shown) for feeding the label paper 101 as a recording medium and a carry motor 103 are driven to carry the label paper 101 continuously.

  Further, when the leading edge detection sensor 105 detects the leading edge of the label in order to determine the recording timing on the label paper 101 conveyed at a constant speed, the detection signal is taken into the CPU 201 via the I / O 208.

  In synchronization with the conveyance of the label paper 101 by the conveyance motor 103, the CPU 201 sequentially reads out the corresponding color image data from the image memory 204, and sends the image data to the corresponding recording heads 104K to 104Y via the recording head control circuit 209. Is transferred and a color image is recorded.

  The operation of the CPU 201 is executed based on various control programs stored in the program ROM 203, whereby the entire inkjet recording apparatus 100 is controlled.

  Such a control program includes, for example, a control program corresponding to a procedure shown in a flowchart (FIG. 3) described later (these control programs use a work RAM 205 as a working memory at the time of execution).

  Returning to FIG. The EEPROM 206 stores, for example, the time when the previous recording head recovery operation (details will be described later) is performed, and a correction value for finely adjusting (registration) the width between the plurality of recording heads and the recording position in the paper transport direction. Is a rewritable nonvolatile memory for storing parameters and the like, or for storing parameters unique to the inkjet recording apparatus 100.

  The CPU 201 receives the detection result of the ink detection sensor 216 via the A / D converter 207 when supplying ink or during the recovery operation of the recording heads 104K to 104Y, and turns on a pressure pump motor 212 and a sub pump motor 213 described later. Drive control is performed via an output port (I / O) 210 and a motor drive unit 211. Various information input from the operation panel 215 is processed by the CPU 201 via the input / output port (I / O) 214, while various information processed by the CPU 201 is processed via the I / O 214. 215.

<Ink flow in inkjet recording apparatus>
Next, the main flow of ink in the inkjet recording apparatus 100 will be described. Here, in particular, (1) the flow of ink when the ink in the ink cartridge 106 is supplied to the sub tank 107 when the ink cartridge 106 is newly installed and ink is supplied during non-recording, and (2) recording The ink flow during the operation for recovering the ejection nozzles of the head 104 to a healthy state (recording head recovery operation) will be described with reference to FIGS. 3A, 3B, and 4. FIG.

  3A is a flowchart showing the flow of operation when the ink in the ink cartridge 106 is supplied to the sub tank 107 in the ink jet recording apparatus 100, and FIG. 3B shows that the ejection nozzles of the recording head 104 are restored to a healthy state. 5 is a flowchart showing a flow of an operation (recording head recovery operation) for causing the recording head to recover. FIG. 4 is a flow chart showing the flow of ink. As described above, the ink jet recording apparatus 100 according to the present embodiment is equipped with four color ink cartridges (106K to 106Y). The flow chart shown in FIG. It is shown (here, for the sake of convenience, description will be made using reference numbers excluding Y, M, C, and K at the end of the reference numbers), and the other colors are configured in the same manner.

<(1) Ink Flow When Supplying Ink in the Ink Cartridge 106 to the Subtank 107 When Ink Supply is performed with a New Ink Cartridge 106>
First, the flow of ink when the ink in the newly installed ink cartridge 106 is supplied to the sub tank 107 will be described with reference to FIGS. 3A and 4.

  The CPU 201 executes the ink supply operation based on the control program stored in the program ROM 203 as follows.

  In step S301, the recycle valve 415 is closed. Subsequently, in step S302, the ink supply valve 402 is opened, and in step S303, the sub pump 213 is driven.

  As a result, the ink inside the ink cartridge 106 is supplied to the sub tank 107 via the needle 416, the ink supply filter 401, the ink supply valve 402, the sub pump 213, and the cooling trap 108. At this time, since the ink supplied from the closed ink cartridge 106 does not contain air, the cooling trap 108 does not operate.

  In step S304, when the ink detection sensor 216 in the sub tank 107 detects the full amount of all colors, the driving of the sub pump 213 is stopped in step S305. When detecting whether or not all colors are full, a timer is monitored, and if a full amount is not reached even after a fixed time has elapsed (in the case of “No” in step S308), a warning is output. (Step S309), the process ends.

  Subsequently, after the ink supply valve 402 is closed in step S306, the recycle valve 415 is opened in step S307, and the process ends. In addition, opening and closing of each valve shall be controlled by applying the solenoid coil etc. which are not shown in figure.

<(2) Ink Flow in Operation (Recording Head Recovery Operation) for Restoring the Discharge Nozzles of the Recording Head 104 to a Healthy State>
Next, with reference to FIGS. 3B and 4, the ink flow in the print head recovery operation for recovering the ejection nozzles of the print head 104 to a healthy state will be described.

  First, the cooling trap 108 in which the refrigerant is sealed in the inner wall is driven, and at the same time, the ink supply valve 402 is closed (step S352), and the driving of the sub pump 213 is started (step S353). Then, an ink suction operation is started from the ink reservoir 413 in the capping mechanism 109 via the recycle filter 414, the recycle valve 415, and the sub pump 213.

  Subsequently, the recovery valve 411 is closed (step S354), and the pressure pump 212 is driven (step S355). Then, the ink in the sub tank 107 is sent to the common liquid chamber 407 of the recording head 104 via the pressurizing pump 212 and the tube 418. However, since the recovery valve 411 is closed, the inside is pressurized and the recording head 104 A relatively large amount of ink is pushed out from each discharge nozzle, and the discharge nozzle is restored to a healthy state.

  The ink pushed out to the ejection nozzle surface 408 temporarily accumulates in the ink reservoir 413 in the capping mechanism 109, but the sub pump 213 is driven with the recycle valve 415 opened in advance and the ink supply valve 402 closed. Thus, after the ink in the ink reservoir 413 is filtered by the recycle filter 414, it is forcibly returned to the sub tank 107 via the recycle valve 415, the sub pump 213, and the cooling trap 108, and the ink used for the recovery operation is not wasted. Recycled.

  At this time, in order to prevent ink from overflowing from the ink reservoir 413, the flow rate by the sub pump 213 is set to exceed the amount of ink falling into the ink reservoir 413.

  Therefore, the sub pump 213 sucks ink together with air. At this point, the ink and air are vigorously mixed to contain countless bubbles, the surface area of the ink increases rapidly, and the humidity in the mixed air also increases rapidly.

  Here, since the cooling trap 108 is operating, the mixed high-humidity air is cooled to lower the saturated water vapor pressure, and moisture is recovered from the mixed air to the ink.

At this time, the ink from which the moisture has been collected returns to the sub tank 107 from the lower flow path of the cooling trap 108, and the cooled and lowered air flows into the sub tank 107 from the upper flow path of the cooling trap and is smaller than the liquid area of the sub tank 107. It passes over the floating plate 421 made of a member having an area smaller than the density of the ink and is discharged from the atmosphere communication port to the atmosphere.
When the above pressurization state is continued and a predetermined time has passed (step S356), the pressurization pump 212 is stopped (step S357), and the recovery valve is opened (step S358). Thereafter, when a certain time has elapsed (step S359), the sub pump 213 and the cooling trap 108 are also stopped (steps S360 and S361), and the process is terminated.

  As is apparent from the above description, according to the present embodiment, during the recording head recovery operation, the ink sucked together with the air through the cap is cooled, and moisture contained in the air is given to the ink before the sub tank. By returning to the configuration, it is possible to avoid an increase in the viscosity of the ink and to realize stable ink ejection over a long period of time.

[Second Embodiment]
The floating plate 421 may be a hollow plate that floats on the ink surface. Further, the cooling section of the cooling trap 108 does not have to be provided for each sub tank 107, and the traps of the respective colors may be surrounded by one cooling section separately from the trap and cooled together.

  Further, instead of using the enclosed liquid refrigerant, a Peltier element or the like may be used as the cooling part of the cooling trap 108.

It is a figure which shows the internal structure in the inkjet recording device concerning one Embodiment of this invention. 1 is a block diagram of an ink jet recording apparatus according to an embodiment of the present invention. 5 is a flowchart illustrating a processing flow when ink is supplied from an ink cartridge to a sub tank in an ink jet recording apparatus. 3 is a flowchart showing a flow of processing during a recording head recovery operation in the ink jet recording apparatus. It is a figure which shows the flow of the ink in an inkjet recording device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Inkjet recording apparatus 101 Label paper 102 Conveying belt 103 Conveying motor 104 Recording head 105 Label leading edge detection sensor 106 Ink cartridge 107 Sub tank 108 Cooling trap 109 Capping mechanism 200 Host computer 201 CPU (central processing unit)
202 Interface controller 203 Program ROM
204 Image memory 205 Work RAM
206 EEPROM
207 A / D converter 208 I / O
209 Recording head control circuit 211 Motor drive unit 212 Pressure pump / motor 213 Sub pump / motor 214 I / O
215 Operation panel 216 Ink detection sensor 401 Supply filter 402 Supply valve 407 Common liquid chamber 408 Discharge face (nozzle) surface 410 Cap 411 Recovery valve 412 Air communication port 413 Ink reservoir 414 Recycle filter 415 Recycle valve 416 Needle 418 Tube 419 Tube 421 Floating Board

Claims (5)

An inkjet recording apparatus that performs recording on a recording medium by discharging ink supplied from a recording head,
A cap that covers the ejection port of the recording head;
A pump connected to the cap and sucking ink supplied to the recording head;
A cooling unit for cooling the ink sucked by the pump,
The ink jet recording apparatus, wherein the ink cooled in the cooling unit is configured to be returned to the tank. The inkjet recording apparatus according to claim 1, wherein the air cooled in the cooling unit is discharged into the atmosphere after passing through the tank. The ink jet recording apparatus according to claim 1, wherein a plate-like member that moves up and down according to a liquid surface position of the stored ink is provided in the tank. An ink supplied to the recording head, comprising: a recording head that discharges ink from an ejection port; a tank that stores ink to be supplied to the recording head; and a first pump that supplies ink to the recording head from the tank. A control method in an ink jet recording apparatus for recording on a recording medium by discharging
Using a cap to cover the discharge port of the recording head;
Using the second pump connected to the cap to suck the ink supplied to the recording head;
Cooling the ink sucked by the second pump;
And a step of returning the cooled ink into the tank. A storage medium storing a control program for realizing the control method according to claim 4 by a computer.

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