JP7750100B2 - liquid discharge device - Google Patents

Description

The present invention relates to a liquid ejection device equipped with a wiper and a cover that covers the end of the nozzle surface.

Patent Document 1 discloses a liquid ejection device (liquid ejection device) equipped with a wiping member (wiper) and a fixed member (cover) that covers the end of the nozzle formation surface (nozzle surface). The fixed member covers the upstream end of the nozzle formation surface in the wiping direction, while leaving the downstream end of the nozzle formation surface in the wiping direction exposed. This makes it easy to wipe the liquid from the nozzle formation surface even if the viscosity of the liquid becomes high.

JP 2013-169700 A

Burrs can form on the edges of the nozzle surface during the process of forming the components that make up the nozzle surface. While the configuration described in Patent Document 1 makes it easy to wipe away highly viscous liquids, the surface of the downstream portion of the fixed member (cover) in the wiping direction is positioned above the nozzle forming surface (nozzle surface), which can cause the wiping member (wiper) to come into contact with and be damaged by burrs formed at the downstream end of the nozzle forming surface (nozzle surface) in the wiping direction.

The object of the present invention is to provide a liquid ejection device that can easily wipe away high-viscosity liquids and minimize damage to the wiper.

The liquid ejection device according to the present invention comprises a nozzle surface having a plurality of nozzles opening therein, a wiper, a movement mechanism for relatively moving the nozzle surface and the wiper, and a control unit. The control unit controls the movement mechanism to perform a wiping process by moving the wiper and the nozzle surface relatively in a wiping direction parallel to the nozzle surface while the wiper is in contact with the nozzle surface. The liquid ejection device further comprises a cover that covers at least the upstream end of the nozzle surface in the wiping direction, the cover having an upstream portion that covers the upstream end of the nozzle surface and a downstream portion that is opposite the upstream portion with respect to the nozzle surface in the wiping direction, and the surface of the downstream portion is located between the nozzle surface and the surface of the upstream portion in a height direction perpendicular to the nozzle surface.

1 is a plan view of a printer 100 according to an embodiment of the present invention. FIG. 2 is a plan view of the head 1 as seen from below. 3 is a cross-sectional view of the head 1 taken along line III-III in FIG. 2. FIG. 4 is a partial enlarged view of FIG. 3 . FIG. 2 is a block diagram showing the electrical configuration of the printer 100.

<Overall printer configuration>
First, with reference to FIG. 1, the overall configuration of a printer 100 according to an embodiment of the present invention will be described.

The printer 100 includes a head unit 1u containing three heads 1, a platen 3, a transport mechanism 4, three wipers 5, and a control unit 10.

The head unit 1u is elongated in the paper width direction (a direction perpendicular to the vertical direction) and is a line type that ejects ink from nozzles 11n (see Figure 2) onto paper 9 while being fixed in position. Each of the three heads 1 is elongated in the paper width direction and is arranged in a staggered pattern in the paper width direction. The underside of each head 1 is a nozzle surface 11x with multiple nozzles 11n opening (see Figure 2). When the driver IC 1x (see Figure 5) of each head 1 is driven under the control of the control unit 10, ink is selectively ejected from the multiple nozzles 11n of each head 1.

The platen 3 is a flat member located below the head unit 1u and extending in a direction perpendicular to the vertical direction. Paper 9 is supported on the upper surface of the platen 3.

The transport mechanism 4 has two pairs of rollers 4a and 4b arranged on either side of the platen 3 in the transport direction (the direction perpendicular to the vertical direction and the paper width direction), and a transport motor 4x (see Figure 5) that rotates the pairs of rollers 4a and 4b. When the transport motor 4x is driven under the control of the control unit 10, the pairs of rollers 4a and 4b rotate while holding the paper 9 between them, and the paper 9 is transported in the transport direction.

Each of the three wipers 5 is a flexible plate-like member arranged vertically and used for wiping (wiping the nozzle surface 11x). Each wiper 5 extends in the paper width direction and overlaps one of the three heads 1 included in the head unit 1u in the transport direction. The wiper 5's home position in the transport direction is between the roller pair 4a and the head unit 1u. When the wiper motor 5x (see Figure 5) is driven under the control of the control unit 10, the wiper 5 moves from its home position in the wiping direction, moving while making contact with the nozzle surface 11x of the corresponding head 1, and then reaches a stopping position between the head unit 1u and the roller pair 4b. The wiping direction is parallel to the nozzle surface 11x and the same direction as the transport direction. The wiper motor 5x corresponds to the "moving mechanism" in this invention.

As shown in Figure 5, the control unit 10 has a ROM (Read Only Memory) 10a, a RAM (Random Access Memory) 10b, and an ASIC (Application Specific Integrated Circuit) 10c. The ROM 10a stores programs and data that the ASIC 10c uses to control various operations. The RAM 10b temporarily stores data used by the ASIC 10c when executing programs. The ASIC 10c performs recording processes, wiping processes, and other operations in accordance with the programs stored in the ROM 10a.

In the recording process, the control unit 10 controls the transport motor 4x based on a recording command (including image data) received from an external device (such as the PC 200 shown in Figure 2) to carry out a transport process in which the paper 9 passes below the head 1 (the space facing the nozzle surface 11x), and controls the driver IC 1x of each head 1 to carry out an ejection process in which ink is selectively ejected from the multiple nozzles 11n of each head 1. This causes an image to be recorded on the paper 9.

During the wiping process, the control unit 10 maintains the acute angle θ between the wiper 5 and the nozzle surface 11x (more specifically, the angle between the wiper 5 and the portion of the nozzle surface 11x downstream of the wiper 5 in the wiping direction) at 45 degrees as shown in FIG. 3, and controls the wiper motor 5x to move the wiper 5 in the wiping direction while in contact with the nozzle surface 11x. The wiper 5 and the nozzle surface 11x move relative to each other. This causes the wiper 5 to wipe away ink and foreign matter (paper dust, etc.) on the nozzle surface 11x.

Although not shown in Figure 3, during the wiping process, the wiper 5 moves in the wiping direction with its tip (upper end) in contact with the nozzle surface 11x and bent.

In this embodiment, the ink ejected from the nozzle 11n is an ink in which the pigment is coated with polymer particles (PP ink: Polymer Particle Ink). The ink present on the nozzle surface 11x is wiped off by the wiper 5.

<Head configuration>
Next, the configuration of the head 1 will be described.

The head 1 has a flow path unit, an actuator unit, a driver IC 1x, and a cover 30.

The flow path unit includes a nozzle plate 11 that forms the nozzle surface 11x, and multiple plates. The nozzle plate 11 and multiple plates are stacked vertically and bonded to each other with an adhesive. Each plate has through-holes and recesses that form the flow path. The nozzle plate 11 is formed by pressing a plate made of metal such as SUS (Steel Use Stainless). The nozzles 11n are formed from through-holes formed in the nozzle plate 11, and form the ends of the flow paths.

The actuator unit is located on the top surface of the flow path unit (the surface opposite the nozzle surface 11x). The actuator unit has an electrode electrically connected to the driver IC 1x, and when the driver IC 1x changes the potential of this electrode, energy is applied to the ink in the flow path of the flow path unit, causing the ink to be ejected from the nozzle 11n.

The cover 30 is attached to the bottom of the flow path unit. The cover 30 is a rectangular frame-shaped member made of epoxy resin that surrounds the periphery of the nozzle surface 11x (see Figure 2). The cover 30 has an upstream section 31 located upstream in the wiping direction, and a downstream section 32 located downstream in the wiping direction (on the opposite side of the upstream section 31 with respect to the nozzle surface 11x in the wiping direction). The upstream section 31 and downstream section 32 are spaced apart in the wiping direction and each extend in the paper width direction. A gate remnant 30g of the cover 30 is present at the downstream end of the downstream section 32 in the wiping direction. The gate remnant 30g is the mark left by a hole used to pour resin material during injection molding.

As shown in FIG. 3, the upstream section 31 covers the upstream end of the nozzle surface 11x in the wiping direction (i.e., overlaps vertically with the nozzle surface 11x). On the other hand, the downstream section 32 does not cover the downstream end of the nozzle surface 11x in the wiping direction (i.e., does not overlap vertically with the nozzle surface 11x). The vertical direction is the direction perpendicular to the nozzle surface 11x, and corresponds to the "height direction" in this invention.

As shown in Figure 2, the nozzle surface 11x is generally rectangular, but has irregularities formed at the downstream end in the wiping direction. In other words, the downstream end of the nozzle surface 11x in the wiping direction has a base 11x1 and a protruding portion 11x2 that protrudes from the base 11x1 downstream in the wiping direction.

As shown in Figures 2 and 3, the downstream portion 32 faces the downstream end of the nozzle surface 11x in the wiping direction and is in contact with the protrusion 11x2 but not with the base 11x1 (i.e., it is spaced apart from the base 11x1 in the wiping direction).

Furthermore, as shown in Figure 3, the upstream portion 31 and downstream portion 32 of the cover 30 have different thicknesses, with the upstream portion 31 being thicker than the downstream portion 32.

The lower surface (surface) of the upstream section 31 and the lower surface (surface) of the downstream section 32 are both located below the nozzle surface 11x, but the lower surface of the upstream section 31 is located below the lower surface of the downstream section 32. In other words, the vertical distance c between the lower surface of the upstream section 31 and the nozzle surface 11x is greater than the vertical distance b between the lower surface of the downstream section 32 and the nozzle surface 11x. In the vertical direction, the lower surface of the downstream section 32 is located between the nozzle surface 11x and the lower surface of the upstream section 31.

As described above, the nozzle plate 11 is formed by pressing a metal plate. In this case, burrs are particularly likely to occur at the edge of the nozzle surface 11x. In this embodiment, the downstream end of the nozzle surface 11x in the wiping direction has irregularities (see Figure 2), and burrs X are likely to occur at the tips of the protrusions 11x2 (see Figure 3).

Here, the protruding height (distance b) of the downstream portion 32 from the nozzle surface 11x is smaller than the protruding height (distance c) of the upstream portion 31 from the nozzle surface 11x, and is also smaller than the distance a between the downstream portion 32 and the base portion 11x1 in the wiping direction, but is greater than the protruding height d of the burr X from the nozzle surface 11x. For example, a = 200 μm, b = 80 μm, c = 250 μm, and d = 20 μm.

During the wiping process, the wiper 5 first contacts the underside of the upstream portion 31 of the cover 30, passes over the step between the upstream portion 31 and the nozzle surface 11x, and then contacts the upstream end of the nozzle surface 11x in the wiping direction. The wiper 5 then moves from the upstream end of the nozzle surface 11x in the wiping direction toward the downstream end (see FIG. 3). At the downstream end of the nozzle surface 11x in the wiping direction, after passing the base 11x1, the wiper 5 contacts the downstream portion 32 of the cover 30 before reaching the tip of the protrusion 11x2 (the portion where the burr X occurs) (see FIG. 4). The wiper 5 then passes over the step between the downstream portion 32 and the nozzle surface 11x without contacting the burr X, and contacts the underside of the downstream portion 32 of the cover 30.

As described above, according to this embodiment, the lower surface (surface) of the downstream portion 32 of the cover 30 is located vertically between the nozzle surface 11x and the lower surface (surface) of the upstream portion 31 of the cover 30 (see FIG. 3). In this case, first, because the downstream portion 32 of the cover 30 protrudes beyond the nozzle surface 11x, during the wiping process, the wiper 5 is likely to come into contact with the downstream portion 32 of the cover 30 before reaching the downstream end of the nozzle surface 11x in the wiping direction (the tip of the protruding portion 11x2 where the burr X occurs). Therefore, even if the burr X occurs at the downstream end of the nozzle surface 11x, the wiper 5 is unlikely to come into contact with the burr X, and damage to the wiper 5 can be suppressed. Furthermore, because the downstream portion 32 of the cover 30 does not protrude further from the nozzle surface 11x than the upstream portion 31, the difference in level between the downstream portion 32 of the cover 30 and the nozzle surface 11x can be kept low, preventing high-viscosity ink from accumulating in the difference in level between the downstream portion 32 of the cover 30 and the nozzle surface 11x. This makes it easier to wipe away high-viscosity ink.

The downstream portion 32 of the cover 30 does not overlap the nozzle surface 11x in the vertical direction (see Figure 3). If the downstream portion 32 of the cover 30 were provided with a portion that covered the nozzle surface 11x, the downstream portion 32 would protrude low from the nozzle surface 11x (the distance b would be small), so the thickness of that portion would need to be thin, making that portion more susceptible to damage. In this regard, in this embodiment, the downstream portion 32 of the cover 30 does not have a portion that covers the nozzle surface 11x, thereby preventing the above-mentioned damage.

The downstream portion 32 of the cover 30 is spaced apart in the wiping direction from the base portion 11x1 at the downstream end of the nozzle surface 11x in the wiping direction (see Figures 2 and 3). During wiping, the wiper 5 is generally positioned so as to form an acute angle with the portion of the nozzle surface 11x downstream of the wiper 5 in the wiping direction (see Figure 3). In this case, if the downstream portion 32 is not spaced apart from the base portion 11x1 in the wiping direction, the wiper 5 will come into contact with the downstream portion 32 before passing through the base portion 11x1, and will not be able to wipe the ink off the base portion 11x1. In this regard, in this embodiment, because the downstream portion 32 is spaced apart from the base portion 11x1 in the wiping direction, the wiper 5 will come into contact with the downstream portion 32 after passing through the base portion 11x1, and will be able to wipe the ink off the base portion 11x1. In addition, in a configuration in which the downstream end of the nozzle surface 11x in the wiping direction has a base 11x1 and a protruding portion 11x2, burrs X are likely to occur at the tip of the protruding portion 11x2 but are unlikely to occur at the base 11x1. In this embodiment, the downstream portion 32 of the cover 30 contacts the tip of the protruding portion 11x2 (the portion where burrs X are likely to occur) and is spaced apart from the base 11x1, so even if the wiper 5 reaches the base 11x1, damage to the wiper 5 by burrs X is suppressed.

The acute angle θ between the wiper 5 and the nozzle surface 11x during wiping is 30 to 60 degrees (45 degrees in this embodiment) (see Figure 3). If the angle θ exceeds 60 degrees, the wiper 5 is more likely to come into contact with the burr X that occurs at the downstream end of the nozzle surface 11x. If the angle θ is below 30 degrees, ink is more likely to accumulate in the step between the downstream portion 32 of the cover 30 and the nozzle surface 11x. In this embodiment, by setting the angle θ to 30 to 60 degrees, both of the above problems can be alleviated. In other words, the effects of easily wiping high-viscosity ink and minimizing damage to the wiper 5 can be more effectively achieved.

During wiping, the acute angle θ between the wiper 5 and the nozzle surface 11x is 45 degrees, and the vertical distance b between the underside of the downstream section 32 and the nozzle surface 11x is smaller than the distance a in the wiping direction between the downstream section 32 and the base 11x1 (see Figure 3). In this case, the requirement that the wiper 5 contacts the downstream section 32 after passing the base 11x1 can be reliably met. This allows the ink on the base 11x1 to be more reliably wiped away.

The conveying direction is the same as the wiping direction (see Figure 1). If the step between the downstream portion 32 of the cover 30 and the nozzle surface 11x (see Figure 3) is large, the paper 9 may get caught on the step, which could easily cause damage or jamming of the paper 9. In this embodiment, however, the step between the downstream portion 32 of the cover 30 and the nozzle surface 11x is low, making it less likely for the paper 9 to get caught on the step and causing damage or jamming of the paper 9.

The cover 30 is made of epoxy resin. In this case, the cover 30 can be produced inexpensively.

The gate remnant 30g of the cover 30 is located in a portion of the cover 30 other than the upstream portion 31 (in this embodiment, the downstream portion 32) (see Figure 2). If the gate remnant 30g were located in the upstream portion 31, the wiper 5 could come into contact with the gate remnant 30g and be damaged. In this embodiment, however, the gate remnant 30g is located in a portion of the cover 30 other than the upstream portion 31, thereby preventing this problem.

The liquid ejected from the nozzle 11n is an ink in which the pigment is coated with polymer particles (PP ink: Polymer Particle Ink). This ink dries quickly, and if it accumulates in the step between the downstream portion 32 of the cover 30 and the nozzle surface 11x, it can accumulate in the step and form large clumps. In this case, the clumps can reach the area of the nozzle surface 11x where the nozzle 11n is formed, causing the nozzle 11n to become clogged. Furthermore, the clumps can cause unevenness in the nozzle surface 11x, which can prevent the nozzle 11n from being properly capped. In this regard, in this embodiment, the step between the downstream portion 32 of the cover 30 and the nozzle surface 11x is low (see Figure 3), preventing ink from accumulating in the step, thereby mitigating this problem.

<Modification>
Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various design modifications are possible within the scope of the claims.

A portion that covers the nozzle surface 11x may be provided in the downstream portion 32 of the cover 30.

The cover 30 is not limited to being made of epoxy resin, but may be made of any material (metal, etc.).

The acute angle θ between the wiper 5 and the nozzle surface 11x during wiping can be between 30 and 60 degrees and is not limited to 45 degrees.

The head 1 is not limited to a line type, but may also be a serial type (a type in which liquid is ejected from nozzles onto the recording medium while moving in a scanning direction parallel to the paper width direction).

The recording medium is not limited to paper 9, but may also be cloth, a substrate, etc.

The liquid ejected from nozzle 11n is not limited to ink in which the pigment is coated with polymer particles. Furthermore, the liquid is not limited to ink and may be any liquid (for example, a treatment liquid that aggregates or precipitates components in the ink).

In the above embodiment, the movement mechanism moves the wiper 5 relative to the fixed head 1, but this is not limited to this, and the head 1 may also be moved relative to the fixed wiper 5.

The present invention is not limited to printers, but can also be applied to facsimiles, copiers, multifunction devices, etc. The present invention can also be applied to liquid ejection devices used for purposes other than image recording (for example, liquid ejection devices that eject conductive liquid onto a substrate to form a conductive pattern).

4 Conveying mechanism 5 Wiper 5x Wiper motor (moving mechanism)
10 Control unit 11n Nozzle 11x Nozzle surface 11x1 Base 11x2 Protrusion 30 Cover 31 Upstream portion 32 Downstream portion 100 Printer (liquid ejection device)
θ angle

Claims (9)

a nozzle surface in which a plurality of nozzles are opened, a wiper, a movement mechanism that moves the nozzle surface and the wiper relatively, and a control unit;
the control unit controls the movement mechanism to perform a wiping process in which the wiper and the nozzle surface are moved relatively in a wiping direction parallel to the nozzle surface while the wiper is in contact with the nozzle surface;
a cover that covers at least an upstream end of the nozzle surface in the wiping direction,
the cover has an upstream portion that covers the upstream end of the nozzle surface and a downstream portion that is on the opposite side of the upstream portion with respect to the nozzle surface in the wiping direction,
In a height direction perpendicular to the nozzle surface, the surface of the downstream portion is located between the nozzle surface and the surface of the upstream portion ,
A liquid ejection device, wherein the distance in the height direction between the surface of the downstream portion and the nozzle surface is 80 μm or less . The liquid ejection device according to claim 1 , wherein the downstream portion does not have a portion that overlaps with the nozzle surface in the height direction. a downstream end of the nozzle surface in the wiping direction includes a base portion and a protruding portion that protrudes from the base portion toward the downstream side in the wiping direction;
The liquid ejection device according to claim 2 , wherein the downstream portion is spaced apart from the base portion in the wiping direction. The liquid ejection device described in claim 3, characterized in that the acute angle formed between the wiper and the nozzle surface during the wiping process is 30 to 60 degrees. the angle is 45 degrees;
The liquid ejection device according to claim 4 , wherein the distance in the height direction between the surface of the downstream portion and the nozzle surface is smaller than the distance in the wiping direction between the downstream portion and the base portion. a conveying mechanism for conveying a recording medium;
the control unit controls the transport mechanism to perform a transport process for transporting the recording medium in a transport direction so as to pass through a space facing the nozzle surface;
6. The liquid ejection device according to claim 1, wherein the transport direction is the same as the wiping direction. The liquid ejection device described in any one of claims 1 to 6, characterized in that the cover is made of epoxy resin. The liquid ejection device described in claim 7, characterized in that the gate remainder of the cover is located in a portion of the cover other than the upstream portion. The liquid ejection device described in any one of claims 1 to 8, characterized in that the liquid ejected from the multiple nozzles is ink in which pigment is coated with polymer particles.