JP2014024210A - Inkjet recording apparatus and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet recording apparatus capable of preventing deterioration in an image quality by performing a required number of times of preliminary discharge to each discharge port to recover a function of a recording head while suppressing consumption of ink and a method for controlling the same.SOLUTION: An inkjet recording apparatus (10) includes recording means for recording an image using a recording head (3) having a discharge port surface (3a) having a plurality of discharge ports (3b) for discharging ink arranged therein, wiping means for wiping the discharge port surface (3a) using a wiper (8), and preliminary discharge means for preliminarily discharging ink not contributing to the recording of the image from the discharge ports (3b). The preliminary discharge means makes the number of times of preliminary discharge from the discharge port (3b) positioned on the upstream side in a wiping direction by the wiper (8) larger than the number of times of preliminary discharge from the discharge port (3b) positioned on the downstream side in the wiping direction.

Description

  The present invention relates to an ink jet recording apparatus and a control method thereof, and more particularly to an ink jet recording apparatus that reduces the amount of liquid used for preliminary ejection of a recording head and a control method thereof.

  In a recording head having a plurality of nozzles for ejecting ink, when ink is ejected, the ink adheres to the periphery of the ejection port at the tip of the nozzle, and the ink may be thickened and fixed. In that case, there is a risk that the image quality will deteriorate due to a change in the amount of ink discharged from the discharge port and the direction of ink discharge.

  As a countermeasure against this, on the surface (ejection port surface) provided with preliminary ejection for ejecting ink that does not contribute to image recording based on the recording data and ejecting thickened ink, bubbles, foreign matter, etc. from the nozzle, and ejection ports. Wiping for wiping off adhered ink or the like with a wiper is known.

  Patent Document 1 discloses a method for improving the wiping performance by preliminarily discharging ink from an ejection port immediately before wiping by a wiper and an ejection port positioned downstream from the ejection port in the wiping direction. ing.

JP 2002-166560 A

  However, according to the method disclosed in Patent Document 1, in order to determine whether to discharge ink from any of the discharge ports on the basis of the position where the wiper contacts the discharge port surface (the position where the discharge port surface is wiped), The wiper position must be detected. Further, in Patent Document 1, since the wiper is a rubber-like elastic body, the amount of deflection of the wiper changes according to the facing distance between the recording head and the wiper, and the position where the wiper contacts the discharge port surface is changed. Change. Therefore, in order to detect the accurate position of the wiper, this change must be taken into account, and the configuration becomes complicated.

  On the other hand, when preliminary ejection is performed, there is a method in which ink that does not contribute to image recording is ejected to the ejection ports the same number of times. However, in this case, there are also ejection ports that perform preliminary ejection beyond the number of ejections necessary to restore the ejection function of the recording head, and these ejection ports cause unnecessary number of ejections and increase ink consumption. Cause.

  The present invention has been made in view of the above problems. The purpose is to perform ink jet recording that can prevent image quality deterioration by performing the required number of preliminary ejections to each ejection port in order to restore the function of the recording head while suppressing ink consumption. An apparatus and a control method thereof are provided.

  In order to solve the above problems, an ink jet recording apparatus according to the present invention includes a recording unit that records an image using a recording head having an ejection port surface in which a plurality of ejection ports for ejecting ink are arranged, and the ejection port surface. An ink jet recording apparatus comprising: a wiping unit that wipes with a wiper; and a preliminary ejection unit that preliminarily ejects ink that does not contribute to image recording from the ejection port. The number of preliminary discharges from the discharge port located on the upstream side is made larger than the number of preliminary discharges from the discharge port located on the downstream side in the wiping direction.

  According to the above configuration, the number of preliminary ink ejections from the ejection ports located upstream in the wiping direction by the wiper is made greater than the number of preliminary ink ejections from the ejection ports located downstream in the wiping direction. By doing so, since the necessary number of preliminary ejections can be set for each ejection port, it is possible to suppress the amount of ink consumed by performing unnecessary number of preliminary ejections. Therefore, in the present invention, in order to restore the function of the recording head while suppressing ink consumption, the required number of preliminary ejections are performed for each ejection port, thereby preventing image quality deterioration. it can.

It is a perspective view which shows the inkjet recording device in embodiment. It is a schematic diagram explaining a mode that a discharge port surface is wiped with a wiper. It is a block diagram which shows the control structure of an inkjet recording device. It is a graph which shows an example of the relationship between the frequency | count of preliminary discharge, and the position of a discharge outlet. It is a graph which shows the other example of the relationship between the frequency | count of preliminary discharge, and the position of a discharge outlet. It is a graph which shows the further another example of the relationship between the frequency | count of preliminary discharge, and the position of a discharge outlet.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing an ink jet recording apparatus 10 (hereinafter referred to as “recording apparatus 10”) in the present embodiment. As shown in the figure, the recording apparatus 10 in this embodiment includes a recording unit 12, a conveyance roller 2, and a recovery unit 6.

  The recording unit 12 includes a carriage 4. The carriage 4 is supported by a guide 5 so that it can reciprocate in the X direction (scanning direction) shown in the figure. The carriage 4 is connected to a drive belt (not shown), and is driven when a driving force from the carriage motor is transmitted through the drive belt.

  The carriage 4 has a recording head 3 and an ink tank 11 mounted thereon. The recording head 3 and the ink tank 11 constitute a head cartridge integrally or separably, or are separately mounted on the carriage without constituting a head cartridge. The ink tank 11 contains ink therein and supplies ink to the recording head 3 from an ink tube (not shown).

  As will be described in detail later, the recording head 3 is provided with a plurality of ejection openings for ejecting ink toward the recording medium 1. The recording head 3 can use a piezo element or an electrothermal transducer as an energy generating element for ejecting ink. In this embodiment, an electrothermal converter is used. In this case, the ink can be foamed by the heat generated by the electrothermal transducer, and the ink can be ejected from the ejection port using the foaming energy.

  The conveyance roller 2 conveys the recording medium 1 in the recording apparatus 10. The conveyance roller 2 is driven by the driving force from the conveyance motor being transmitted through a transmission mechanism (not shown). The conveyance roller 2 conveys the recording medium 1 in the Y direction (conveyance direction) shown in the drawing by rotating while sandwiching the recording medium 1 between the conveyance roller 2 and the pinch roller 9.

  While the recording unit 12 reciprocates in the X direction (scanning direction) intersecting with the Y direction, the recording scanning for ejecting ink from the recording head 3 based on the recording data and the conveying operation of the recording medium 1 by the rollers 2 and 9 are repeated. As a result, an image is formed on the recording medium 1.

  The recovery unit 6 includes a cap 7 and a wiper 8. The recovery unit 6 recovers the function of the recording head 3. The cap 7 protects the surface (discharge port surface) where the discharge port of the recording head 3 is provided. The cap 7 is connected to a suction pump (not shown). By attaching the cap 7 to the recording head 3 and operating the suction pump, the pressure in the cap 7 is set to a negative pressure, and the ink or the like adhering to the ejection port surface is sucked. The wiper 8 performs wiping to wipe off ink or the like adhering to the discharge port surface.

  Wiping is performed, for example, after the recording head ejects a predetermined amount of ink due to a recording operation, etc., after a period of time when the recording head does not eject ink, or after the ink is sucked by the suction pump, etc. Is done.

  The recovery unit 6 reciprocates in the direction perpendicular to the ejection port surface of the recording head 3 (Z direction shown in the figure), so that the cap 7 is attached to or removed from the recording head 3. Further, the recovery unit 6 wipes the ejection port surface of the recording head 3 using the wiper 8 by moving in a direction opposite to the Y direction (W direction shown in the drawing). The moving direction of the recovery unit 6 during the wiping may be the Y direction.

  Further, the wiping direction may be along a discharge port array constituted by a plurality of discharge ports, or may not necessarily be along the discharge port row. In the present embodiment, a case where wiping is performed along the ejection port array will be described.

  In the present embodiment, the cap 7 and the wiper 8 are housed in one housing and constitute the recovery unit 6, but they do not necessarily have to be housed in one housing, Each may be housed in a separate housing.

  In the present embodiment, one wiper 8 is shown in FIG. 1, but the number of wipers that can be applied to the present invention is not limited to this, and may be one or more. The wiper 8 can be formed of a deformable elastic body in order to wipe off ink or the like without damaging the discharge port surface.

  FIG. 2 is a schematic diagram for explaining how the ejection port surface 3 a of the recording head 3 is wiped by the wiper 8. As shown in the figure, the recording head 3 has a plurality of discharge ports 3b on the discharge port surface 3a. The plurality of discharge ports 3b are arranged along the Y direction to form a discharge port array. A plurality of the discharge port arrays are provided, and they are arranged in parallel. In the figure, the recording head 3 has three ejection port arrays, but the number of ejection port arrays is not limited to three, and may be three or more, or less than three. There may be.

  The wiper 8 wipes the discharge port surface 3a along the W direction. This wiping is sequentially performed on the plurality of discharge ports 3b. Therefore, each discharge port constituting the discharge port array can be classified for convenience on the upstream side and the downstream side in the wiping direction. Wiping is performed from upstream to downstream. Therefore, there is a difference in the timing of wiping between the discharge port located upstream in the wiping direction (W direction) and the discharge port located downstream in the wiping direction. That is, the wiping ends at the discharge port positioned upstream in the wiping direction earlier than the discharge port positioned downstream in the wiping direction.

  In addition, with the passage of the recording operation time and the rest time after wiping, the probability of ink adhesion and ink thickening around the ejection port increases. Therefore, such a situation is likely to occur at the discharge port located on the upstream side in the wiping direction in which the elapsed time after wiping is longer than that on the downstream side in the wiping direction. Therefore, it is desirable that the number of times of preliminary discharge after wiping is increased in the discharge port located on the upstream side than in the discharge port located on the downstream side.

  In this embodiment, paying attention to the difference in elapsed time after wiping, the number of preliminary ejections for ejecting ink that does not contribute to image recording is controlled. That is, the number of preliminary discharges of the discharge ports located on the upstream side in the wiping direction is made larger than the number of preliminary discharges of the discharge ports located on the downstream side in the wiping direction. By so doing, thickened ink, mixed color ink, foreign matter, bubbles, etc. around the discharge port or in the nozzle can be discharged by the number of preliminary discharges suitable for each discharge port. Therefore, the function of the recording head 3 can be restored by performing the necessary number of preliminary ejections to each ejection port without performing wasteful preliminary ejection.

  Next, the control configuration of the recording apparatus 10 will be described. FIG. 3 is a block diagram showing a control configuration of the recording apparatus 10. As shown in the figure, the recording apparatus 10 is connected to a host apparatus 200. Image data is transmitted from the host apparatus 200 to the recording apparatus 10. The recording device 10 performs image processing on the image data input from the host device 200, generates recording data that can be recorded by the recording head 3, and records an image based on the recording data.

  As shown in FIG. 3, the recording apparatus 10 includes a CPU 100, a ROM 101, a RAM 102, a motor driver 103A, a motor driver 104A, a recording head driver 105, and a recovery unit driver 106.

  Various programs are recorded in the ROM 101. The RAM 102 is used as a work area or memory area for the CPU 100. The CPU 100 controls the entire recording apparatus 10 according to a program recorded in the ROM 101. That is, the CPU 100 controls the motor driver 103A, the motor driver 104A, the recording head driver 105, and the recovery unit driver 106, respectively. In the present embodiment, the number of preliminary ejections is controlled by the control by the CPU 100.

  The motor driver 103A drives the carriage motor 103, and the motor driver 104A drives the transport motor 104. The carriage motor 103 reciprocates the carriage 4 in the main scanning direction (X direction shown in FIG. 1). The transport motor 104 rotates the transport roller 2 and the pinch roller 9 for transporting the recording medium 1.

  The recording head driver 105 drives the recording head 3. The recording head drivers 105 are provided corresponding to the number of recording heads 3. The recovery unit driver 106 controls the recovery unit 6. That is, the recovery unit driver 106 controls the cap 7, the wiper 8, and the discharge recovery pump of the recording head 3 that constitute the recovery unit 6. The recovery unit driver 106 also controls the movement operation of the recovery unit 6.

  Next, a method for controlling the number of preliminary ejections in the present embodiment will be described. The relationship between the number of preliminary ejections and the position of the ejection port can be optimally set according to the characteristics of the recording head and ejected ink. In the following, three examples are given.

  FIG. 4 is a graph showing an example of the relationship between the number of preliminary discharges and the position of the discharge port in the present embodiment. In the figure, the vertical axis represents the number of preliminary ejections, and the horizontal axis represents the position of the ejection port in the ejection port array of the recording head 3. As shown in the figure, in this embodiment, the relationship between the number of preliminary discharges and the position of the discharge port is determined so that the number of preliminary discharges gradually decreases from the upstream side to the downstream side in the wiping direction. .

The figure shows that y ₀ > y ₁ > 0 and y ₀ when the number of preliminary discharges of the discharge port located upstream in the wiping direction is y ₀ and the number of preliminary discharges of the discharge port positioned downstream is y _1. = F (x) indicates the number of preliminary ejections controlled by a function that satisfies the condition of f (x) ≦ 0.

  In the present embodiment, as indicated by the above function, the number of preliminary discharges of the discharge ports located on the upstream side in the wiping direction is controlled to be larger than the number of preliminary discharges of the discharge ports located on the downstream side, The number of preliminary discharges for each discharge port is determined. As described above, in the present embodiment, by controlling the number of preliminary ejections of each ejection port to the number of preliminary ejections indicated by the above function, preliminary ejection corresponding to the elapsed time after each wiping is performed on each ejection port. The number of times can be determined. As a result, the function of the recording head 3 can be recovered while suppressing the ink consumption, and the deterioration of the image quality can be prevented.

  FIG. 5 is a graph showing another example of the relationship between the number of preliminary ejections and the position of the ejection port. In the same figure, as in the example of FIG. 4, the vertical axis indicates the number of preliminary ejections, and the horizontal axis indicates the position of the ejection port in the recording head 3. In this example, the number of preliminary ejections and the position of the ejection port are in a proportional relationship so that the number of preliminary ejections decreases at a constant value from the upstream side toward the downstream side in the wiping direction. Therefore, the amount of change in the number of preliminary ejections is constant. That is, in this example, the number of preliminary discharges from the discharge port is decreased at a constant rate from the most upstream side to the most downstream side in the wiping direction.

  In the present embodiment, the number of preliminary ejections required to restore the function of the recording head 3 to each of the ejection port located on the most upstream side in the wiping direction and the ejection port located on the most downstream side in the wiping direction. To decide. Then, the number of preliminary ejections of each ejection port other than these standard ejection ports is changed at a constant rate.

  As another method, the number of preliminary ejections required to restore the function of the recording head 3 at the randomly selected ejection ports is determined, and the ejection ports are moved from the most upstream side to the most downstream side in the wiping direction. Alternatively, the number of preliminary discharges may be changed at a constant rate. Any method may be used as long as the number of preliminary ejections can be changed at a constant rate.

  By determining the number of preliminary discharges by these methods, the number of preliminary discharges of the discharge ports located on the upstream side in the wiping direction is made larger than the number of preliminary discharges of the discharge ports located on the downstream side. Preliminary discharge can be performed as many times as necessary for each discharge port.

  FIG. 6 is a graph showing still another example of the relationship between the number of preliminary ejections and the position of the ejection port. In the same figure, as in the example of FIG. 4, the vertical axis represents the number of preliminary ejections, and the horizontal axis represents the position of the ejection port in the recording head 3. In this example, the relationship between the number of preliminary discharges and the position of the discharge port is set so that the number of preliminary discharges decreases stepwise from the upstream side toward the downstream side in the wiping direction.

  In this example, the number of preliminary discharges is gradually reduced from the upstream side to the downstream side in the wiping direction. That is, in this example, the discharge port array is divided into two or more portions, and the number of preliminary discharges of the discharge ports located in each portion is determined. In this example, as shown in FIG. 6, the discharge port array is divided into five ranges including the upstream side and the downstream side in the wiping direction, and the number of preliminary discharges of the discharge ports located in each range is determined. However, the number of ranges to be divided is not limited to five, and may be at least two.

  That is, in this example, the number of preliminary discharges from a plurality of discharge ports located adjacent to each other in the wiping direction among the plurality of discharge ports in the region on the discharge port surface is the same. In addition, a plurality of sets of the plurality of discharge ports having the same number of preliminary discharges are set.

  Also in this example, the number of preliminary discharges of the discharge ports located upstream in the wiping direction is made larger than the number of preliminary discharges of the discharge ports positioned downstream. By doing so, it is possible to perform preliminary ejection as many times as necessary for each ejection port located in each range. Compared with the example of FIGS. 4 and 5 in which the number of preliminary discharges is determined for each discharge port, in this example, the burden on the CPU 100 that controls the number of preliminary discharges can be reduced.

(Other embodiments)
In the embodiment described above, wiping and preliminary discharge are performed independently, but they may be performed in association with each other.

  Due to the wiping, there is a possibility that the inks of a plurality of colors adhering to the discharge port surface are mixed on the discharge port surface, and this mixed color ink adheres to the periphery of the discharge port or enters the nozzle. Further, foreign matter including ink may enter the nozzle due to wiping. In this case, it is desirable to perform preliminary discharge continuously after wiping.

  For example, paying attention to the elapsed time since the previous wiping, the number of preliminary ejections to be continuously performed after the current wiping is controlled. That is, similarly to the above-described embodiment, the number of preliminary discharges of the discharge ports located on the upstream side in the wiping direction is made larger than the number of preliminary discharges of the discharge ports located on the downstream side in the wiping direction. By so doing, thickened ink, mixed color ink, foreign matter, bubbles, etc. around the discharge port or in the nozzle can be discharged by the number of preliminary discharges suitable for each discharge port.

  Therefore, the function of the recording head can be restored by performing the necessary number of preliminary ejections to each ejection port without performing unnecessary preliminary ejection.

  In the above-described embodiment, the case of using a serial type recording head has been described. However, a full line type recording head can also be used. Even when a full-line type recording head is used, the number of preliminary ejections from the ejection ports located upstream in the wiping direction is made larger than the number of preliminary ejections from the ejection ports located downstream in the wiping direction. By doing so, the same effect as the above-described embodiment can be obtained.

3 Recording Head 3a Discharge Port Surface 3b Discharge Port 8 Wiper 10 Recording Device

Claims (8)

A recording means for recording an image using a recording head having a discharge port surface in which a plurality of discharge ports for discharging ink are arranged;
Wiping means for wiping the discharge port surface with a wiper;
A pre-ejection unit that pre-ejits ink that does not contribute to image recording from the ejection port;
The preliminary ejection means is characterized in that the number of preliminary ejections from the ejection port located upstream in the wiping direction by the wiper is made larger than the number of preliminary ejections from the ejection port located downstream in the wiping direction. Inkjet recording apparatus.   The inkjet recording apparatus according to claim 1, wherein the wiping unit performs wiping with the wiper along an ejection port array configured by the plurality of ejection ports.   3. The inkjet according to claim 1, wherein the preliminary ejection unit decreases the number of preliminary ejections from the ejection port at a certain rate from the most upstream side to the most downstream side in the wiping direction. Recording device.   The preliminary ejection means is the number of times required to restore the function of the recording head to each of the ejection port located on the most upstream side in the wiping direction and the ejection port located on the most downstream side in the wiping direction. The number of preliminary discharges is determined, and the number of preliminary discharges of each discharge port other than the discharge port located on the most upstream side and the discharge port located on the most downstream side is changed at a constant rate. The ink jet recording apparatus according to claim 3.   2. The preliminary ejection unit sets the same number of preliminary ejections from a plurality of ejection ports located adjacent to each other in the wiping direction among a plurality of ejection ports in a region on the ejection port surface. Or the inkjet recording apparatus according to 2;   The inkjet recording apparatus according to claim 5, wherein the preliminary ejection unit sets a plurality of sets of the plurality of ejection ports that have the same number of preliminary ejections.   The ink jet recording apparatus according to claim 1, wherein the number of preliminary ejections by the preliminary ejection unit is controlled according to an elapsed time after the wiping. A recording means for recording an image using a recording head having a discharge port surface in which a plurality of discharge ports for discharging ink are arranged;
Wiping means for wiping the discharge port surface with a wiper;
A preliminary ejection unit that preliminarily ejects ink that does not contribute to image recording from the ejection port, and a control method for an inkjet recording apparatus,
Control of an ink jet recording apparatus, wherein the number of preliminary ejections from the ejection port located upstream in the wiping direction by the wiper is made larger than the number of preliminary ejections from the ejection port located downstream in the wiping direction. Method.

Images