JP2014140990A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve following problem that when an opening/closing valve is blocked when an ink tank is not attached to, drive must be performed at low torque for preventing blowing of ink from a supply needle, but when hardness of the opening/closing valve is enhanced for improving agitation efficiency, opening/closing disability of the opening/closing valve occurs more often, so that drive must be performed at high torque.SOLUTION: At least two modes of valve closing operation speed are provided. In an area where ink does not blow or blowing amount of ink is in an allowable range, and load of the opening/closing valve is heavy, drive must be performed at high torque. In an area where ink does not blow and load of the opening/closing valve is light, drive must be performed at low torque.

Description

  The present invention relates to an ink supply technique having an ink tank capable of storing ink of an ink jet recording apparatus.

  A general ink jet recording apparatus (hereinafter also referred to as a recording apparatus) includes an ink tank that can store ink, a recording head, a supply channel that connects the ink tank and the recording head, and a valve that can shut off the supply channel. An image is formed on a recording medium by ejecting ink from the ejection port formed on the recording medium. In recent years, to reduce downtime, a sub-tank is provided between the supply channels, and even if the ink tank becomes empty, image formation continues with the ink in the sub-tank (hereinafter also referred to as stopless printing). An increasing number of devices can replace the ink tank.

  In general, the ink used in the recording apparatus is a dye-based or pigment-based water-based ink containing an insoluble or hardly soluble color material. The color material in the ink aggregates and precipitates over time, and the ink density is not uniform in the ink tank or sub tank. When image formation is performed using ink with a non-uniform density, the image quality is degraded. End up. In order to solve the problem of uneven ink density, there is a recording apparatus provided with means for periodically stirring the ink in the ink tank.

  As a stirring means, a method using a variable volume valve (hereinafter also referred to as an on-off valve) is known. The volume-changing ink tank that can be attached to and detached from the recording apparatus has two connection parts at the bottom, and one is supplied via two hollow supply needles connected to the downstream end of the supply flow path. The other of the flow paths can communicate with the atmosphere. The on-off valve closes and opens the supply channel, but when the on-off valve operates from closed to open (hereinafter also referred to as valve opening operation), the ink in the supply channel is sucked and the on-off valve operates from open to closed When doing (hereinafter also referred to as valve closing operation), the ink in the supply flow path is discharged. The on-off valve is always urged in the closing direction by a compression spring via a spring holder, and the cam can be opened by pushing the lever connected to the spring holder and rotating the lever around the central axis of the lever to push up the spring holder. The cam can be positioned by a photo sensor, and the rotation of the cam is controlled via a gear by a DC motor as a drive source.

  By alternately and continuously operating the valve opening operation and the valve closing operation, an ink flow is caused in the supply flow path, and the ink is blown into the ink tank through the supply needle to perform stirring (Patent Document 1). ). In order to further enhance the stirring effect, there is one in which a rib is provided inside the ink tank (Patent Document 2).

  However, in the configuration in which the ink tank is detachable from the recording apparatus, the opening / closing valve is closed when the ink removal operation is performed at the end of stopless printing, when the power is turned off, or when the recording apparatus is transported. If the valve closing operation is performed when the ink tank is not installed, the discharged ink may be ejected from the supply needle. The ejected ink is collected in the blown ink storage part provided around the supply needle, and then absorbed by the ink absorber from the drain provided in the blown ink storage part. The reservoir may be exceeded.

  Therefore, as a measure against ink blowing, the valve closing speed is at least two modes or more, and when the ink tank is not installed, the opening valve is closed in the low speed mode to suppress ink blowing and prevent surrounding parts from being stained with ink. (Patent Document 1).

JP 2007-245350 A Japanese Patent No. 4795129

  As a result of repeated experiments by the present inventor, when the content of the ink tank is increased, the flow of ink is difficult to flow around the entire ink tank, so the stirring effect is reduced and the uneven concentration in the ink tank is eliminated. I found it difficult. As one of the methods for improving the effect of stirring, a method of increasing the power for discharging ink by increasing the hardness of the on-off valve is employed. However, if the hardness of the on-off valve is increased, ink ejection when the ink tank is not installed is also promoted. In particular, in a recording apparatus including a sub tank, the ink tank is not installed easily, and the chance of ink ejection increases.

  In general, the opening / closing control of the on-off valve is performed by a DC motor. In this case, in order to close the on-off valve at a low speed, the on-off valve must be driven with a low torque. If the load during the closing operation is increased, the valve closing operation may not be performed due to insufficient torque. In addition, the DC motor that controls the on-off valve generally has an inertial force. When the DC motor is driven at a high torque, the inertial force increases, and there is a problem that the stop position varies.

  In order to solve the above problem, the present invention is characterized in that the valve opening / closing speed (valve opening / closing torque) has at least two modes and the valve opening / closing speed is switched during the valve closing or valve opening operation. Also, in the valve closing operation, it is driven at a high torque in a region where the load of the on-off valve is high and the ink is not blown or allowed, and is driven at a low torque in a region where the load of the on-off valve is low and the ink blows out. Features. Further, in the valve opening operation, the valve is driven with high torque in a region where the load of the on-off valve is high, and is driven with low torque in a region where the load of the on-off valve is low.

  According to the present invention, even when the force for discharging the ink in the supply flow path is increased in order to enhance the agitation effect, it is possible to prevent the ink from being blown out and prevent the surrounding parts from being stained with ink, and the inertia of the DC motor. Variations in the stop position due to force can be minimized.

Schematic diagram of ink jet recording apparatus according to the present invention 1 is a conceptual diagram of a color flow path of an ink supply device according to the present invention. Block diagram of the present invention Conceptual diagram of one color flow path of ink supply device for explaining stirring operation of this embodiment Cam diagram of this embodiment, photosensor shading, transmission position, cam torque transition, and motor torque diagram Sequence diagram of valve closing operation of this embodiment Sequence diagram of valve opening operation of this embodiment Conceptual diagram of one color flow path of ink supply device for explaining valve closing operation of this embodiment Sequence diagram of valve closing operation of this embodiment

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

  FIG. 1 is a conceptual diagram of the ink jet recording apparatus of this embodiment.

  In FIG. 1, the ink jet recording apparatus 50 is fixed so as to straddle the upper ends of two leg portions 55 facing each other. The recording head 1 is mounted on the carriage 60. At the time of recording, the recording medium set in the transport roll holder unit 52 is fed to the printing position, and the carriage 60 has a carriage motor (not shown) and belt transmission means. 62, reciprocating in the main scanning direction indicated by arrow B, and ink droplets are ejected from each nozzle of the recording head 1 during this movement. When the carriage 60 moves to one end of the recording medium, the conveyance roller 51 conveys the recording medium by a predetermined amount in the sub-scanning direction indicated by the arrow A. In this way, an image is formed on the entire recording medium by alternately repeating the recording operation and the conveying operation. After the image formation, the recording medium is cut by a cutter (not shown), and the cut recording medium is stacked on the stacker 53.

  The ink supply unit 63 includes ink tanks 5 (detachable to the apparatus) that are separated for each ink color such as black, cyan, magenta, and yellow, and the ink tank 5 and the supply tube 2 are connected to each other. . Further, the supply tube 2 is bundled by a tube guide 61 so as not to be violated when the carriage 60 reciprocates.

  A surface of the recording head 1 facing the recording medium has a plurality of nozzle rows (not shown) in a direction substantially orthogonal to the main scanning, and is connected to the supply tube 2 in units of nozzle rows.

  Further, a recovery unit 70 is provided at a position outside the recording medium range in the main scanning direction and facing the nozzle surface of the recording head 1. The recovery unit 70 performs cleaning of the nozzle that sucks out ink or air from the surface of the ejection nozzle of the recording head 1 and suction for forcibly sucking out air accumulated in the recording head as necessary.

  An operation panel 54 is provided on the right side of the recording apparatus 50. When the ink in the ink tank 5 becomes empty, a warning message is issued and an announcement is given to the user to prompt the user to replace the ink tank 5. .

  Next, FIG. 2 shows a conceptual diagram of one color flow path of the ink supply device of the present invention.

  As shown in FIG. 2, the volume-invariant ink tank 5 that can be attached to and detached from the apparatus has two joint portions at the bottom, and the joint portions are the first hollow tube 8 and the second intermediate portion of the apparatus. It is connected to the empty tube 9. The first hollow tube and the second hollow tube are composed of metal needles. A standing wall 42 is formed around the second hollow tube 9 in the ink tank 5 from the bottom surface of the ink tank. When a small amount of current is passed through the first and second hollow tubes and the ink remaining amount is lower than the standing wall 42, the resistance value of the current increases, so that the amount of ink in the ink tank 5 increases. The near end can be detected.

  The second hollow tube 9 communicates with the atmosphere communication chamber 6, and the ink tank 5 communicates with the atmosphere via the atmosphere communication passage 7 in the atmosphere communication chamber. Further, the bottom surface 45 of the ink tank 5 and the top surface 46 of the sub-tank 4 whose volume does not change communicate with each other through the first hollow tube 8, and the sub tank 4 and the recording head 1 communicate with each other through the supply tube 2. The sub-tank 4 is constituted by an inclined surface 49 whose cross-sectional area increases as it goes downward in the vertical direction over substantially the entire top surface, and is connected to the first hollow tube 8 at the highest position 46. A solid tube 10 made of metal is provided in the sub tank 4. Whether or not the ink in the sub tank is full is detected by a resistance value when a weak current is passed through the first hollow tube 8 and the solid tube 10. The ink outlet from the sub tank 4 is provided at the lowest position 48 of the side surface 47. Between the sub tank 4 and the supply tube 2, there is provided an on-off valve 3 made of a flexible member capable of changing the volume capable of opening and closing the supply flow path.

  The on-off valve 3 is always urged in the closing direction by a compression spring 38 via a spring holder 34, and a cam 37 pushes a lever 39 connected to the spring holder 34 and rotates about a central axis 40 of the lever 39, thereby spring holder It can be opened by pushing 34 up. The cam 37 can be positioned by a photo sensor 41 and is rotationally controlled via a gear 36 by a DC motor 35 as a drive source (in this embodiment, the reduction ratio of the cam is 64.5). A blown ink reservoir 81 having an open top surface is provided around the hollow tube 8 to store the blown-out ink and then absorbed by the ink absorber 83 from a drain 82 provided in the blown ink reservoir.

  The sub-tank 4 stores ink so that image formation can be continued when the ink in the ink tank 5 is used up. When the ink in the sub-tank 4 is consumed, air passes through the ink tank 5 from the atmosphere communication path 7. Is introduced into the sub tank 4. The introduced air accumulates in the upper part of the sub tank 4 and the first hollow tube and the solid shaft 10 in the 8 are not connected by ink, so that it becomes difficult for electricity to flow and the ink in the sub tank 4 is consumed. Can be detected. Until the ink tank 5 is replaced, the ink use allowable amount in the sub-tank 4 (about 11 ml in this embodiment, the amount of ink that can be printed at a density of 100% on the maximum size paper in this printer) is reached. Can continue image formation. In this embodiment, the ink tank capacity is 100 ml, and the ink tank capacity is 30 ml.

  FIG. 3 shows the internal configuration of the recording apparatus.

  In FIG. 3, a CPU 11 for controlling the recording device 50, a user interface 12 including a key operated by a user and an operation panel for displaying information, a ROM 13 containing control software, and temporarily used when operating the control software. The RAM 14, the I / O 15 to the drive unit of the recording apparatus 50, the drive portion 16 of the recording apparatus 50, and the ink remaining amount sensor 17 that detects the remaining amount of the ink tank. The near end is detected by looking at the resistance values of the currents of the two metal needles described above. The ink tank mounting sensor 18 that detects the removal of the ink tank makes a determination based on the reading value of the EEPROM 20 mounted on the ink tank. The contents of the EEPROM 20 are read and written using the ink tank mounting sensor 18.

  FIG. 4 is a conceptual diagram of the on-off valve operation and the stirring operation of the present embodiment. 4A is a diagram of the valve opening operation, and FIG. 4B is a diagram of the valve closing operation.

  As shown in FIG. 4A, when the on-off valve 3 is changed from the closed state to the open state, the ink of the capacity V1 (0.45 ml in this embodiment) corresponding to the volume change of the on-off valve 3 from the ink tank 5 opens the sub tank 4. Then, the air is drawn into the on-off valve 3 and simultaneously air or ink is drawn into the ink tank 5 from the atmosphere communication chamber 6. Thereafter, when the on-off valve 3 is changed from the open state to the closed state as shown in FIG. 4B, the ink having the capacity V1 corresponding to the volume change of the on-off valve flows into the ink tank 5 through the sub tank 4, and at the same time. Ink flows from the ink tank 5 into the atmosphere communication chamber 6. When ink flows into the ink tank 5, ink flows in the ink tank 5. At that time, ink flows also in the sub tank 4. By repeating the opening and closing operation, the flow can be continuously generated, and the ink in the ink tank 5 and the sub tank 4 can be stirred. At this time, since the pressure loss of the ink supply flow path from the on-off valve 3 to the recording head 1 is much larger than the pressure loss from the on-off valve 3 to the ink tank 5, almost no ink flows to the recording head 1 side. Therefore, the volume change of the on-off valve 3 flows into and out of the ink tank 5, and the ink in the ink tank 5 can be stirred with almost no loss.

  Details of the first embodiment will be described with reference to FIGS.

  FIG. 5 is a diagram of the cam 37 used in the present embodiment, the light shielding and transmission position of the photosensor 41, the torque transition of the cam 37, and the motor torque. FIG. 6 is a sequence diagram of the valve closing operation used in this embodiment.

  In FIG. 5, in the valve closing operation, the cam 37 moves from the light shielding detection position (b1) of the photosensor 41 to the transmission detection position (b2) of the photosensor 41 and stops at the start of the operation. The torque of the cam 37 in the b1-b2 section (valve closing operation) is M2 (800 gf · cm in this embodiment) in the b1-a3 section (open / close valve open), and M2 to M3 (in this embodiment) in the a3-a4 section. 0gf · cm) and is M3 in the a4-b2 section (open / close valve closed). Further, d2 is controlled by time T1 (2400 msec in this embodiment) so as to be in the section a3-a4, and T1 is the momentum of the blown ink does not exceed the blown ink storage part 81, and the volume of the blown ink storage part 81 And the sum of the drained ink capacities.

  In the low-speed valve closing operation, the on-off valve 3 is open in the b1-a3 section and the volume does not change, so that ink ejection does not occur. In the a3-d2 section, the ink ejection amount can be allowed. In the example, it is driven at 15%) (S603). In the d2-b2 section, the on-off valve 3 changes in the volume decreasing direction and the torque decreases, so that it is driven at a low torque (PWM4, 10% in this embodiment) (S610). Ink blowing can be prevented and stop position accuracy can be improved.

  In the normal valve closing operation, ink ejection does not occur because the ink tank is installed. Therefore, it may be driven with a higher torque (PWM2, 33% in this embodiment) than the low-speed valve closing operation.

  Similarly, details of the second embodiment will be described with reference to FIGS.

  FIG. 7 is a sequence diagram of the valve opening operation used in this embodiment.

  In FIG. 5, in the valve opening operation, the cam 37 moves from the transmission detection position (b2) of the photosensor 41 to the light shielding detection position (b1) of the photosensor 41 and stops at the start of the operation.

  The shape of the cam 37 used in the present embodiment is such that the valve opening height h of the on-off valve 3 near the start of the valve opening operation is greatly changed, and the valve opening height h of the on-off valve 3 near the end of the valve opening operation is changed small. Is set to Further, a frictional force is generated between the cam 37 and the lever 39 that pushes up the compression spring 38 when the valve is opened. Therefore, the torque of the cam 37 in the b2-b1 section (valve opening operation) increases from M3 in the b2-a1 section (open / close valve closing), and from M3 to M1 (2100 gf · cm in this embodiment) in the a1-c1 section, It decreases from M1 in the c1-c2 section, from M1 to M2 in the c2-c3 section, and becomes M2 in the a2-b1 section (open / close valve closed).

  Since the b2-d1 section includes a section where the torque is maximum, the driving is performed with a high torque (PWM1, 99% in this embodiment) (S702), and the torque decreases in the d1-b1 section, so the low torque (PWM2). (S708), the stop position accuracy can be improved. d1 is controlled at time T3 (500 msec in this embodiment) so as to be within the interval c2-a2, and T3 is set to a position where the torque of the cam 37 sufficient to drive with low torque is reduced.

  In the first and second embodiments, the torque switching timing (S607, S705) uses the time from the start of the valve closing operation. However, a new photo sensor is provided to detect the switching position. It doesn't matter.

  Details of the third embodiment will be described with reference to FIGS.

  In FIG. 5, when the torque is switched between the b2-d2 section and the d2-b2 section in the valve closing operation, by providing a waiting time T2 (1000 msec in the present embodiment) (S609), the balloon is blown before d2, and Since the ink stored in the blown ink storage unit 81 can be drained, the overflow of the ink from the blown ink storage unit 81 is prevented. Further, by providing a waiting time, the ink flow in the sub tank 4 and the supply flow path is stabilized, and the momentum of the ejected ink can be weakened, so that the ejected ink is scattered outside the ejected ink storage portion 81. prevent.

  Further, in this embodiment, since ink ejection is suppressed by providing a waiting time, it is not always necessary to switch the torque.

Further, a region where the volume of the on-off valve does not change may be provided depending on the shape of the cam 37.
Similarly, a waiting time T4 may be provided when switching the torque during the valve opening operation.

  Details of the fourth embodiment will be described with reference to FIG.

  FIG. 8 is a schematic view of the sub tank full tank detection position of the present embodiment. FIG. 9 is a sequence diagram used in this embodiment.

  In FIG. 8, the position of the solid tube 10 that detects that the ink in the sub-tank is not full is set when the ink is consumed by V2 or more, and V2 is the volume V1 and V2> V1 corresponding to the volume change of the on-off valve 3. It is a relationship.

  When the valve is closed when the ink tank is not installed, a low-speed valve closing operation sequence is used to switch the torque if the ink in the sub tank 4 is full. If the ink is not full, the on-off valve 3 is discharged when the valve is closed. Since the ink is stored in the sub-tank and the ink does not blow out, a normal valve closing operation sequence that is driven with high torque is used (S902).

1 Recording head 2 Ink tube (ink flow path)
3 On-off valve 4 Sub tank 5 Ink tank 6 Atmospheric communication chamber 8 First hollow tube 9 Second hollow tube 10 Solid 18 Ink attachment sensor 20 EEPROM
34 Spring holder 35 DC motor 36 Gear 37 Cam 38 Compression spring 39 Lever 40 Center shaft 41 Photo sensor 50 Inkjet recording device 54 Operation panel 60 Carriage 63 Ink supply unit 81 Blow out ink reservoir 82 Drain 83 Ink absorber

Claims (5)

A print head that discharges ink onto a recording material and performs recording; an in-tank that holds the ink; an ink channel that guides ink from the ink tank to the print head; and an ink channel that is in the middle of the ink channel In an ink jet recording apparatus having a variable volume valve capable of blocking a flow,
An ink jet recording apparatus, wherein the valve has at least two valve speeds and is configured to be able to switch between a valve shut-off speed or a valve open speed during an operation of shutting off or opening the ink flow path. 2. The ink jet recording apparatus according to claim 1, wherein the valve shutoff speed or valve opening speed to be switched is such that the initial speed is faster than the final speed. The ink jet recording apparatus according to claim 1, wherein a waiting time is provided between the valve shutoff speed and the valve opening speed. The valve opening / closing speed includes a high speed mode for stirring the ink in the ink tank, a medium speed mode for opening / closing the valve when the ink tank is mounted, and a low speed mode for opening / closing the valve when the ink tank is not mounted. The inkjet recording apparatus according to any one of claims 1 to 3. A sub-tank for storing ink between the ink tank and the valve and capable of confirming the stored ink capacity;
Use the medium speed mode when installing the ink tank.
When the ink tank is not installed, the medium speed mode is used when the ink in the sub tank is used more than a predetermined amount, and the low speed mode is used when the ink in the sub tank is not used more than a predetermined amount. The inkjet recording apparatus according to any one of claims 1 to 4.