JP2006056202A - Inkjet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive inkjet recorder which is downsized by using fewer component items. <P>SOLUTION: The inkjet recorder is provided with: an inkjet recording head 33 discharging ink droplets; a cap 88 storing ink from the inkjet recording head 33; and a second pump 98 sucking ink from a discharge surface of the inkjet recording head 33 via the cap 88 when the inkjet recording head 33 is recovered. The inkjet recorder is also provided with: a three-way valve 94 provided on the downstream side of the second pump 98; a controller 56 controlling a flowing direction of the three-way valve 94; a reusing ink line 97 connected to the three-way valve 94 and flowing ink to be reused via a filter 99; and a waste ink line 95 flowing ink to be disposed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an inkjet recording apparatus that records ink on a recording medium by ejecting ink droplets from an inkjet recording head.

  2. Description of the Related Art Inkjet recording apparatuses that perform recording by ejecting ink droplets from an ejection surface of an inkjet recording head toward a recording medium are widely used. In such an ink jet recording apparatus, a liquid receiver (cap) that stores the discharge liquid is disposed as a liquid receiver at a position facing the discharge surface.

  When recording is started after leaving the ink jet recording apparatus for a long time, as a recovery operation of the ink jet recording head, the cap is pressed against the head discharge surface to be in the mounted state (ON state), and the thickened ink near the discharge port (nozzle) is applied. Going to suck out. The sucked ink passes through the filter and is then collected in a collection tank for collecting ink. Further, a replenisher for making the recovered thickened ink have an appropriate viscosity is supplied from the replenishment tank to the recovery tank. Then, the ink in the collection tank is re-supplied to the ink bottle after being made to have an appropriate viscosity, and reused (for example, see Patent Document 1).

  However, the provision of a collection tank and a replenishment tank increases the number of parts, which hinders downsizing of the apparatus and increases the cost. Furthermore, since a detecting means for detecting the amount of ink in the recovery tank is required, there is a problem that the cost is further increased. In addition, the filter is likely to be clogged, and the filter life is short.

Since one cap is provided for one ink jet recording head, when an FWA (Full Width Array) type ink jet recording head is used, a large amount of ink flows through the filter (general scanning method). This problem is particularly serious in comparison with the inkjet recording head of the present invention.
JP 2003-127435 A

  In view of the above facts, an object of the present invention is to provide a low-cost inkjet recording apparatus that is reduced in size by reducing the number of parts.

  The present inventor examined the cause of clogging with a filter. It was noted that the thickened ink sucked out at the beginning of the recovery operation passed through the filter. Then, it has been found that paper dust and dust adhering to the nozzle and cap are mixed in the thickened ink, and the filter is clogged by the paper dust and dust. It has also been found that the filter life is shortened by passing paper dust, dust and thickened ink through the filter.

  As a result of intensive studies, the present inventor has come up with the idea of discarding paper powder, dust, thickened ink and the like without passing through a filter. Then, by discarding in this way, it has been found that some of the components necessary in the prior art are unnecessary, and further studies have been made to complete the present invention.

  According to the first aspect of the present invention, an ink jet recording head that ejects ink droplets, a liquid receiver that contains ink from the ink jet recording head, and ink is sucked out from the ejection surface of the ink jet recording head via the liquid receiver. An ink jet recording apparatus comprising: a suction unit; a switching unit that is provided on a downstream side of the suction unit and that switches an outflow direction of the ink sucked from the suction unit; and a controller that controls the switching unit. A reuse ink line that is connected to the switching means and flows ink to be reused through a filter, and a waste ink line that is connected to the switching means and flows ink for waste liquid treatment, and the controller includes: The ink from the suction start by the suction means is allowed to flow to the waste ink line, and the waste ink Ink so that flow into the reusable ink line when determining a set amount of ink flows into lines, and switches the flow direction of the switching means.

  The set amount is often determined according to the amount of thickened ink in the vicinity of the ejection port.

  According to the first aspect of the present invention, a set amount of ink for waste liquid treatment, that is, a thickened ink containing a large amount of paper dust or dust does not pass through the filter, and almost no paper dust, dust and thickened ink are passed. Ink that does not contain flows through the reuse ink line and passes through the filter.

  Thereby, when the recovery operation of the ink jet recording head is performed, it is not necessary to adjust the viscosity of the ink with the replenishing liquid, so that the collection tank and the replenishing tank which are conventionally required are not necessary. Therefore, it is possible to realize a small-sized and low-cost inkjet recording apparatus. Further, clogging hardly occurs in the filter, and the filter life is prolonged.

  The invention according to claim 2 is characterized in that the switching means is a three-way valve.

  Thereby, the structure of a switching means can be simplified.

  The invention according to claim 3 is characterized in that the set amount is a volume of the liquid receiver.

  Thereby, the amount of ink discarded during the recovery operation can be sufficiently reduced.

  The invention according to claim 4 is characterized in that the set amount is a total value of the volume of the liquid receiver and the volume of the flow path from the liquid receiver to the valve.

  Thereby, the ink which passes the filter of a reuse ink line can be made into the ink which does not contain paper dust, dust, and thickening ink reliably.

  Since the present invention is configured as described above, it is possible to realize a low-cost inkjet recording apparatus that is reduced in size by reducing the number of parts.

  Hereinafter, embodiments will be described and embodiments of the present invention will be described. In the second and subsequent embodiments, the same components as those already described are denoted by the same reference numerals and description thereof is omitted.

[First Embodiment]
First, the first embodiment will be described.

(overall structure)
FIG. 1 shows an ink jet recording apparatus 12 according to a first embodiment of the present invention. A paper feed tray 16 is provided in the lower part of the casing 14 of the ink jet recording apparatus 12, and the sheets P stacked in the paper feed tray 16 can be taken out one by one by a pickup roll 18. The taken paper P is transported by a plurality of transport roller pairs 20 constituting a predetermined transport path 22. Hereinafter, the term “transport direction” simply refers to the transport direction of the paper P that is a recording medium.

  Above the paper feed tray 16, an endless transport belt 28 stretched around a drive roll 24 and a driven roll 26 is disposed. A recording head array 30 is disposed above the conveyor belt 28 and faces the flat portion 28F of the conveyor belt 28. This opposed area is an ejection area SE where ink droplets are ejected from the recording head array 30. The sheet P transported along the transport path 22 is held by the transport belt 28 and reaches the discharge area SE, and ink droplets corresponding to image information are attached from the recording head array 30 in a state of facing the recording head array 30. The

  Then, by rotating the paper P while being held by the transport belt 28, the paper P can be passed through the discharge region SE a plurality of times, and so-called multipass image recording can be performed. Therefore, the surface of the conveyance belt 28 is a circulation path of the paper P in the present invention.

For example, the transport belt 28 is made of a semiconductive polyimide material (surface resistance value 10 ¹⁰ to 10 ¹³ Ω / □, volume resistance value 10 ⁹ to 10 ¹² Ω · cm), thickness 75 μm, width 380 mm, circumference What was shape | molded in length 1000mm can be used. Moreover, as the drive roll 24 and the driven roll 26, as an example, a φ50 mm SUS roll can be used.

  Further, without providing the conveyor belt 28, for example, a recording medium (paper P) may be sucked and held on the outer periphery of a conveyance roller formed in a cylindrical shape or a columnar shape and rotated. However, when the conveyor belt 28 is used as in the present embodiment, the flat portion 28F is formed, so that the recording head array 30 can be arranged corresponding to the flat portion 28F, which is preferable.

  In this embodiment, the recording head array 30 has a long shape in which the effective recording area is equal to or larger than the width of the paper P (the length in the direction orthogonal to the transport direction), and is yellow (Y) and magenta (M). , Cyan (C), and Black (K), four inkjet recording head units 32 (hereinafter simply referred to as head units 32) corresponding to the four colors are arranged along the transport direction to record full-color images. It is possible. The method of ejecting ink droplets in each head unit 32 is not particularly limited, and a known method such as a so-called thermal method or piezoelectric method can be applied.

  The ink jet recording head 33 constituting each head unit 32 is controlled by a head controller 60. For example, the head controller 60 determines the ejection timing of the ink droplets and the ink ejection port (nozzle) to be used according to the image information, and sends a drive signal to the inkjet recording head 33.

  The recording head array 30 may be stationary in a direction orthogonal to the transport direction. However, if the recording head array 30 is configured to move as necessary, an image with higher resolution can be obtained by multi-pass image recording. Or failure of the ink jet recording head 33 is not reflected in the recording result.

  Above the head unit 32, reservoir tanks 64 corresponding to four colors of yellow (Y), magenta (M), cyan (C), and black (K) are arranged.

  Four maintenance units 34 corresponding to the respective head units 32 are arranged in the vicinity of the recording head array 30 (in this embodiment, both sides in the transport direction). When performing maintenance on the head unit 32, as shown in FIG. 2, the recording head array 30 moves upward, and the maintenance unit 34 moves into the gap formed between the conveyance belt 28 and enters. . Then, a predetermined maintenance operation (vacuum, dummy jet, wiping, capping, etc.) is performed in a state of facing the nozzle surface 33N (see FIGS. 3 and 6) which is a discharge surface.

  In the present embodiment, the four maintenance units 34 are divided into two sets of two, and the recording head array 30 is arranged on the upstream side in the transport direction and the downstream side in the transport direction of the recording head array 30 during image recording. I am doing so.

  As shown in detail in FIG. 3, a charging roll 36 to which a power source 38 is connected is disposed on the upstream side in the transport direction of the recording head array 30. The charging roll 36 is driven while sandwiching the conveyance belt 28 and the paper P with the driven roll 26, and moves between a pressing position for pressing the paper P against the conveyance belt 28 and a separation position separated from the conveyance belt 28. It is possible. At the pressing position, a predetermined potential difference is generated between the grounded driven roll 26 and the sheet P can be charged and electrostatically attracted to the transport belt 28.

As the charging roll 36, for example, a roll having a diameter of 14 mm can be used in which conductive rubber is coated on the surface of silicone rubber and the volume resistance value is adjusted to about 10 ⁶ to 10 ⁷ Ω · cm.

  As the power source 38, a DC power source is shown in FIG. 3, but an AC power source may be used as long as the paper P can be charged to a predetermined potential.

  A registration roll (not shown) is provided further on the upstream side in the transport direction than the charging roll 36, and the paper P is aligned before reaching between the transport belt 28 and the charging roll 36.

  A peeling plate 40 (see FIGS. 1 and 2) is disposed on the downstream side in the transport direction of the recording head array 30, and the paper P can be peeled from the transport belt 28. As the peeling plate 40, for example, an aluminum plate having a thickness of 0.5 mm, a width of 330 mm, and a length of 100 mm can be used.

  The peeled paper P is transported by a plurality of rotatable discharge roller pairs 42 constituting a discharge path 44 on the downstream side in the transport direction of the peeling plate 40, and is discharged to a paper discharge tray 46 provided at the upper part of the housing 14. Discharged.

  Below the peeling plate 40, a cleaning roll 48 is disposed so that the conveyance belt 28 can be sandwiched between the drive roll 24 and the surface of the conveyance belt 28 is cleaned.

  A reversing path 52 including a plurality of reversing roller pairs 50 is provided as a reversing unit between the paper feed tray 16 and the conveying belt 28, and the sheet P on which an image is recorded on one side is reversed and conveyed. By holding the belt 28, image recording on both sides of the paper P can be easily performed.

  Between the conveyance belt 28 and the paper discharge tray 46, an ink tank 54 for storing each of the four color inks is provided. The ink in the ink tank 54 is supplied to each head unit 32 through an ink supply line 62 (see FIG. 5). As the ink, various known inks such as water-based ink, oil-based ink, and solvent-based ink can be used.

  As shown in FIG. 4, the entire inkjet recording apparatus 12 is controlled by a controller 56, and operations including image recording, discharging, and maintenance are performed from taking out the paper P. Various data relating to the recorded image is sent from the image controller 58 to the controller 56. For example, as will be described later, the applied voltage and the like in the first charging mode and the second charging mode are controlled by the controller 56 in accordance with the data of the recorded image. The inkjet recording head 33 is controlled by a head controller 60, and a signal is transmitted from the controller 56 to the head controller 60. The controller 56, the head controller 60, and the charging roll 36 are supplied with power from a power source 38.

  In the ink jet recording apparatus 12 of the present embodiment configured as described above, the paper P taken out from the paper feed tray 16 is transported to the transport belt 28 as described above. Then, it is pressed against the conveyor belt 28 by the charging roll 36 and is held by being attracted (contacted) to the conveyor belt 28 by the voltage applied from the charging roll 36. In this state, while the paper P passes through the ejection area SE by circulation of the transport belt, ink droplets are ejected from the recording head array 30 and an image is recorded on the paper P. When an image is recorded in only one pass, the paper P is peeled off from the transport belt 28 by the peeling plate 40, transported by the discharge roller pair 42, and discharged to the paper discharge tray 46. On the other hand, when performing image recording by multi-pass, after the paper P is circulated and passed through the ejection area SE until the required number of times is reached, the paper P is peeled off from the transport belt 28 by the paper P with the peeling plate 40, The paper is conveyed by the discharge roller pair 42 and discharged to the paper discharge tray 46.

(Ink flow line)
As shown in FIG. 5, the ink jet recording apparatus 12 is used for an ink supply line 62 for supplying ink from the ink tank 54 to the head unit 32, and for maintenance (when the ink jet recording head 33 is restored). An ink outflow line 63 in which the outflow direction can be switched is provided for each color.

  In the following, one color (for example, yellow) will be described in which ink is supplied from the ink tank 54 to the head unit 32 through the ink supply line 62 and ink is sucked from the ink outflow line 63 during the recovery operation of the ink jet recording head 33. To do. Since the other colors are the same, the description thereof is omitted.

  An unused ink filter 66 is provided between the ink tank 54 and the reservoir tank 64 in the ink supply line 62.

  The ink jet recording apparatus 12 includes a reservoir tank filling pump 68 that is provided on the upstream side of the ink flow of the unused ink filter 66 and applies an ink delivery force to the ink supply line 62, and a reservoir tank filling pump 68. And a filling motor 70 to be driven. The filling motor 70 is controlled by the controller 56.

  Further, in order to monitor the amount of ink in the reservoir tank 64, a sensor 72 for detecting the presence or absence of ink at the low position L and the high position H in the reservoir tank 64 is provided. Data measured by the sensor 72 is transmitted to the controller 56.

  The head unit 32 includes one sub tank 77, a plurality of differential pressure valves 79 provided below the sub tank 77, and a plurality of ink jet recording heads 33 provided below each differential pressure valve 79 (FIGS. 6 and 6). 7), and the differential pressure valve 79 generates a head back pressure in the ink jet recording head 33 via the sub tank 77. In addition, the reservoir tank 64 and the sub tank 77 are connected by piping, and the sub tank 77 and the differential pressure valve 79 are connected by piping so that the ink flowing out from the reservoir tank 64 can reach the inkjet recording head 33 via the differential pressure valve 79. The differential pressure valve 79 and the ink jet recording head 33 are connected by piping.

  As shown in FIGS. 6 and 7, the lower surface side of the ink jet recording head 33 is a nozzle surface 33N, and 1024 nozzles 78 are arranged.

  The differential pressure valve 79 is not particularly limited as long as it is a valve capable of generating a differential pressure.

  As shown in FIG. 5, the maintenance unit 64 is connected to the cap 88 that receives the ink from the nozzle surface 33N by being pressed against the nozzle surface 33N during the recovery operation of the ink jet recording head 33, and the outlet of the cap 88. And an ink outflow pipe 92 having a three-way valve 94 connected to the end thereof. The three-way valve 94 can switch the outflow direction, and the switching of the outflow direction is controlled by the controller 56.

  Further, a waste ink line 95 is provided which is connected to the three-way valve 94 and flows ink for waste liquid treatment. A waste ink tank 96 is provided at the downstream end of the waste ink line 95.

  Further, a reusable ink line 97 is provided which is connected to the three-way valve 94 and allows ink to be reused to flow. The reuse ink line 97 is provided with a recovery filter 99, and the downstream end of the reuse ink line 97 is connected to the reservoir tank 64.

  Further, the ink jet recording apparatus 12 includes a recovery operation pump 98 that sucks out ink from the cap 88 to the ink outflow pipe 92, and a recovery operation motor 100 that drives the recovery operation pump 98. The recovery operation motor 100 is controlled by the controller 56 similarly to the filling motor 70.

  Hereinafter, the recovery operation of the inkjet recording head 33 will be described with reference to FIG.

  When the recovery operation is started (step S1), the controller 56 determines whether or not the remaining amount of ink in the reservoir tank 64 is equal to or larger than the volume of the cap 88 (step S2).

  If it is determined that the remaining amount of ink in the reservoir tank 64 is not greater than or equal to the capacity of the cap 88, the reservoir tank filling pump 68 is driven (step S3). When it is determined that the ink level of the reservoir tank 64 has reached the high position H (step S4), the drive of the reservoir tank filling pump 68 is stopped (step S5).

  When the ink remaining amount in the reservoir tank 64 exceeds the capacity of the cap 88, the three-way valve 94 is switched so as to flow to the waste ink line 95 (step S6).

  Then, the cap 88 is pressed against the nozzle surface 33N of the ink jet recording head 33 to be in a mounted state (ON state) (step S7). Further, the recovery operation pump 98 is driven (step S8).

  If the controller 56 determines that the ink of the volume of the cap 88 has flowed out based on the total rotational speed of the recovery operation pump 98 (step S9), the controller 56 switches the outflow direction of the three-way valve 94 to the reuse ink line 97 ( Step S10).

  Further, when the controller 56 determines that a necessary amount of ink has flowed out in the recovery operation based on the total number of revolutions of the recovery operation pump 98 (step S11), the controller 56 stops driving the recovery operation pump 98 (step S12). ).

  Then, the cap 88 is separated from the nozzle surface 33N and turned off (step S13), and the wiping operation for the nozzle surface 33N is performed (step S14).

  Then, the recovery operation is terminated (step S15).

  As a result, the ink at the initial stage of suction when the ink jet recording head 33 performs the recovery operation, that is, the thickened ink in which a large amount of paper powder, dust, or the like is mixed, is treated as a waste liquid without passing through the recovery filter 99. . Then, ink containing almost no paper dust, dust, and thickening ink passes through the recovery filter 99 of the reuse ink line 97. Therefore, clogging hardly occurs in the recovery filter 99, and the life of the recovery filter 99 is extended.

  Further, since the ink that has passed through the recovery filter 99 contains almost no thickening ink, there is no need to provide a recovery tank or a replenishment tank in the apparatus as in the prior art. Therefore, the ink jet recording apparatus 12 can be made small and low cost.

  Further, the differential pressure valve 79 has a small and simple structure, and can be disposed on the upper side of the ink jet recording head 33. This is also advantageous for reducing the size of the inkjet recording apparatus 12.

  The differential pressure valve 79 also functions as a check valve. Therefore, even if a jam or the like occurs and the head position changes, bubbles are not drawn from the nozzle 78 of the inkjet recording head 33. Further, even if the ink level fluctuates in the reservoir tank 64 due to vibration or the like, the ink does not bleed out from the nozzle 78 or bubbles do not get drawn in.

[Second Embodiment]
Next, a second embodiment will be described. As shown in FIG. 8, in the present embodiment, the determination in step S9 ′ is performed instead of step S9, as compared to the first embodiment.

  That is, the controller 56 determines that a total amount of ink corresponding to the volume of the cap 88 and the volume of the ink outflow pipe 92 has flowed out based on the total rotational speed of the recovery operation pump 98 (step S9 ′). The outflow direction of the three-way valve 94 is switched to the reuse ink line 97 (step S10).

  As a result, all the thickened ink mixed with paper powder, dust, etc. is treated as waste without passing through the recovery filter 99. Then, ink containing no paper dust, dust, and thickening ink passes through the recovery filter 99 of the reuse ink line 97. Therefore, compared with the first embodiment, clogging is less likely to occur in the recovery filter 99, and the life of the recovery filter 99 is further increased.

  The embodiments of the present invention have been described above with reference to the embodiments. However, these embodiments are merely examples, and various modifications can be made without departing from the scope of the invention. Needless to say, the scope of rights of the present invention is not limited to the above embodiment.

It is a front sectional view showing the configuration of the ink jet recording apparatus of the first embodiment in an image recording state. It is a front sectional view showing the composition of the ink jet recording device of a 1st embodiment in a maintenance state. FIG. 2 is a conceptual front view illustrating a configuration of a conveyance belt and its vicinity of the ink jet recording apparatus according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration of a control system of the ink jet recording apparatus according to the first embodiment. It is a schematic diagram which shows the ink flow line of the inkjet recording device of 1st Embodiment. 6A and 6B are a side view and a rear view, respectively, showing the configuration of the ink jet recording head of the first embodiment. It is a flowchart figure which shows the operation procedure at the time of performing recovery operation | movement with the inkjet recording device of 1st Embodiment. It is a flowchart figure which shows the operation procedure at the time of performing recovery operation | movement with the inkjet recording device of 2nd Embodiment.

Explanation of symbols

12 Inkjet recording device 33 Inkjet recording head 33N Nozzle surface (ejection surface)
56 Controller 88 Cap (liquid receiver)
92 Ink outflow pipe (flow path)
94 Three-way valve (switching means, three-way valve)
95 Waste ink line 97 Reused ink line 98 Recovery operation pump (suction means)
99 Recovery filter (filter)

Claims (4)

Inkjet recording comprising: an inkjet recording head that ejects ink droplets; a liquid receiver that contains ink from the inkjet recording head; and a suction unit that sucks out ink from the ejection surface of the inkjet recording head via the liquid receiver. A device,
A switching unit that is provided on the downstream side of the suction unit and switches an outflow direction of the ink sucked from the suction unit;
A controller for controlling the switching means;
A reusable ink line connected to the switching means and flowing reusable ink through a filter;
A waste ink line that is connected to the switching means and feeds ink for waste liquid treatment;
With
The controller is configured to cause the ink from the suction start by the suction means to flow to the waste ink line, and to determine that a set amount of ink has flowed to the waste ink line, the switch to flow ink to the reuse ink line. An ink jet recording apparatus, wherein the flow direction of the means is switched.   2. The ink jet recording apparatus according to claim 1, wherein the switching means is a three-way valve.   The inkjet recording apparatus according to claim 1, wherein the set amount is a volume of the liquid receiver.   The inkjet recording apparatus according to claim 1, wherein the set amount is a total value of a volume of the liquid receiver and a volume of a flow path from the liquid receiver to the valve.

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