JP2018122493A - Liquid discharging device, method for controlling liquid discharging device and image formation device - Google Patents

Abstract

Provided is a technique for detecting a decrease in liquid recovery capability of a recovery member in an apparatus for discharging a liquid provided with a recovery member that recovers by charging a liquid that is generated during scanning of a recording head and floats on an airflow. . SOLUTION: A liquid discharge head 165 for discharging a liquid, recovery members 200 and 210 for recovering floating liquid when a voltage is applied, and a leak current detection means 300 for detecting a leak current value from the recovery member. Prepared. [Selection] Figure 10

Description

  The present invention relates to an apparatus for ejecting liquid, a control method for an apparatus for ejecting liquid, and an image forming apparatus.

  2. Description of the Related Art An inkjet image forming apparatus that forms an image by ejecting recording liquid (ink) droplets from a recording head is known. Since this image forming apparatus has a structure in which liquid droplets are ejected from the recording head, a part of the liquid droplets are separated during the flight, or landed on the recording medium when the ink hits the recording medium (paper, etc.). Droplet (hereinafter referred to as ink mist). The ink mist is scattered inside the apparatus, and as a result, adheres to the inside of the image forming apparatus or is discharged outside the apparatus through a gap in the exterior. The ink mist adhering to the inside / outside of the image forming apparatus becomes dirty, and causes a problem that the fingers and clothes are soiled when touched by the user and the surroundings where the image forming apparatus is installed are soiled.

Furthermore, when the ink mist applies a voltage to the optical sensor (reflection type, transmission type, encoder, recovery member) inside the image forming apparatus, there is a problem that a leakage current is generated and the ink recovery capability is reduced or a failure occurs. is there.
Patent Document 1 discloses a method of collecting ink mist by a platen by charging a platen disposed opposite to the ejection side of a recording head to form an electric field.
However, this ink recovery method also increases the leakage current when a voltage is applied to the platen as the amount of ink mist deposited on the platen as a charging member increases, resulting in a decrease in ink recovery capability and ink mist recovery. There is a problem that a system failure or a capacity reduction occurs.
As described above, in the ink mist recovery system using the conventional charging member, the leakage current when the voltage is applied to the charging member increases as the amount of mist accumulated on the charging member increases, and the failure and capability of the ink mist recovery system. There was a problem of inviting a decline.

  The present invention provides a technique for detecting a decrease in liquid recovery capability by a recovery member in an apparatus for discharging a liquid provided with a recovery member that recovers by charging a liquid that is generated during scanning of a recording head and floats on an airflow. The purpose is to do.

  In order to achieve the above object, an apparatus for discharging liquid according to the present invention includes a liquid discharge head for discharging liquid, a recovery member for recovering floating liquid when a voltage is applied, and a leakage current value from the recovery member. And a leakage current detecting means for detecting.

  According to the present invention, the amount of leakage current when a voltage is applied to the recovery member (charging member) is detected, whether maintenance is necessary or not, and whether or not there is a failure is determined. Correction can be made so that the ink mist collecting ability is not lowered.

1 is a diagram illustrating a schematic configuration of an ink jet printer as an example of an image forming apparatus including an apparatus for discharging a liquid according to an embodiment of the present invention. It is a block diagram which shows the electric constitution of an inkjet printer. It is a figure explaining the generation | occurrence | production principle of ink mist. (A) is a block diagram of an electrostatic adsorption conveyance belt, (b) is a figure explaining the alternating charge in an electrostatic adsorption conveyance belt. It is a figure explaining the generation | occurrence | production state of the ink mist by charging of an electrostatic adsorption conveyance belt. It is a figure explaining a printing area (scanning area of a carriage). (A) thru | or (d) is a figure explaining the airflow which generate | occur | produces by the scanning of a carriage. (A) is a figure explaining the structural example which has arrange | positioned the ink mist collection | recovery member (collection member) which concerns on one Embodiment of this invention to the right-and-left both sides board of an exterior, (b), (c) produces a short circuit. It is a figure explaining a principle. It is a block diagram explaining the structural example for applying a voltage to an ink mist collection | recovery member. It is a circuit block diagram for implement | achieving the method of detecting the leakage current amount of an ink mist collection | recovery member. It is a flowchart which shows the operation | movement flow in leak current amount detection. It is a figure explaining the countermeasure according to the amount of leak current amount. It is a flowchart which shows the control procedure which concerns on the correction mode (1) of voltage application. It is a flowchart which shows the control procedure which concerns on voltage application correction mode (2). It is a figure which shows an example of the circuit structure for implement | achieving a power-up mode control method. (A) (b) And (c) is a figure which shows the structural example which has arrange | positioned the ink mist collection | recovery member in locations other than a side plate.

Hereinafter, the present invention will be described in detail with reference to embodiments shown in the drawings.
<Basic configuration of image forming apparatus>
FIG. 1 is a diagram illustrating a schematic configuration of an ink jet printer as an example of an image forming apparatus including an apparatus for ejecting liquid according to an embodiment of the present invention.
In the present invention, when ink mist (floating fine droplets) is collected in a device for ejecting liquid, electric power is input in accordance with the airflow generated in the apparatus by the reciprocating motion of the carriage carrying the recording head (liquid ejection head). The recovery member (ink mist recovery member) that is activated when the ink mist floats in the air stream is placed at an appropriate number in an appropriate location and recovered according to the operation of the carriage and the recording head. A configuration that controls the voltage (ON / OFF switching, voltage value, ON / OFF timing, etc.) applied to the member has one feature.

The apparatus for ejecting a liquid according to the present invention is not applied only to an ink jet printer, but can be applied to an image forming apparatus using all kinds of liquids and powders.
The ink jet printer 100 includes an image forming unit 101 that forms an image on a sheet P, a sheet feeding unit 120 that supplies a sheet P as a recording medium to the image forming unit, and a sheet from the sheet feeding unit to the image forming unit 101. A sheet conveying unit 130 that conveys and a sheet discharging unit (sheet discharge tray) 140 that stocks the sheet P on which an image is formed (recorded) in the image forming unit 101 are provided.

The paper feeding unit 120 is disposed opposite to the paper tray 121 on which the paper P is loaded, the half-moon roller (paper feeding roller) 123 that separates and feeds the paper one by one from the paper stacking unit, and the friction coefficient of the friction coefficient. A separation pad 124 made of a large material is provided, and this separation pad is urged toward the sheet feeding roller.
A transport unit 130 for transporting paper fed from the paper feed unit 120 on the lower side of the recording head 165 and a transport belt 131 for transporting the paper by electrostatic attraction and paper fed substantially vertically upward Is provided with a conveyance guide 135 for changing the direction approximately 90 ° to follow the conveyance belt, and a tip pressure roller 136 urged toward the conveyance belt by a pressing member. In addition, a charging roller 138 which is a charging unit for charging the surface of the conveyance belt is provided.

The conveyor belt 131 is an endless belt, and is looped around the conveyor roller 132 and the tension roller 133 in the belt conveyance direction. The charging roller 138 is disposed so as to come into contact with the surface layer of the transport belt and to be rotated by the rotation of the transport belt.
Further, the paper discharge unit 140 for discharging the paper recorded by the recording head 165 includes a separation claw 141 for separating the paper from the conveyance belt, and a paper discharge roller 142, and is provided below the paper discharge roller. A paper discharge tray 143 is provided.

Next, FIG. 2 is a block diagram showing an electrical configuration of the ink jet printer.
The inside of the dotted line in FIG. 2 shows the components of the control board, and the outside of the dotted line shows the unit (power supply, various control objects, sensors, etc.) connected to the control board.
The control board 222 includes a power supply circuit that receives power supply from the power supply. The control board 222 is connected to an operation panel (OPERATION PANEL) for inputting and displaying information necessary for the inkjet printer 100. The control board receives print data or the like from the host side such as an information processing device such as a personal computer, an image reading device such as an image scanner, an imaging device such as a digital camera, and the like via a cable or a network via a HOST I / F. Then, the CPU (control means) reads and analyzes the print data in the reception buffer included in the HOST I / F, performs necessary image processing, data rearrangement processing, and the like in the CPU, and sends an image to the HEAD control unit. Transfer data. The dot pattern data for image output may be generated by storing font data in a ROM, for example, or the image data is developed into bitmap data by a host-side printer driver and transferred to this apparatus. You may do it.

When the head control unit receives image data (dot pattern data) corresponding to one line of the recording head, the dot control data for one line is sent to the carriage as serial data in synchronization with the clock signal. A latch signal is sent to the carriage at a predetermined timing.
The HEAD drive unit includes a waveform generation circuit including a DAC (D / A converter) that reads pattern data of a drive waveform (head drive signal) stored in the ROM, and D / A converts the drive waveform data, and an amplifier. Including a driving waveform generating circuit.

  A HEAD mounting section called a carriage has a shift register that inputs a clock signal from the head control section and serial data that is image data, a latch circuit that latches a register value of the shift register with a latch signal from the head control section, A level conversion circuit (level shifter) for changing the output value of the latch circuit, an analog switch array (switch means) whose on / off is controlled by the level shifter, and the like are included. Then, by controlling on / off of the analog switch array, a required driving waveform included in the driving waveform is selectively applied to the actuator means of the recording head mounted in the carriage to drive the recording head.

Further, the CPU receives a sensor detection signal via an ADC (A / D converter) that performs A / D conversion.
The main scanning, sub-scanning motor, and supply motor driving units send drive signals to the main scanning motor and sub-scanning motor in response to command signals from the CPU to excite the motors, and drive the motors to read the movements of the motors with encoder sensors. The rotation speed of the motor is controlled by feeding back the read result to the CPU.
Generated by the high-voltage circuit by managing the conveyance amount of the conveyor belt according to the number of pulses of the sub-scan encoder output in response to the driving of the sub-scan motor, and outputting a control signal to the high-voltage circuit for every fixed conveyance amount Invert the high pressure polarity.

Next, the principle of ink mist generation will be described with reference to FIG.
The main causes of the occurrence of ink mist can be due to the trailing edge of the droplet during ejection from the recording head 165 and due to the bounce after landing on the paper surface. When a uniform electric field is present when ink mist is generated, the charge distribution of the ink mist is biased in one direction due to the action of electrostatic induction, even if the original droplet is electrically neutral. That is, when the transport belt side is positively charged, a negative charge is induced in the droplet transport belt side portion, and a positive charge is induced in the portion opposite to the droplet transport belt. .
Since the ink mist separated from the droplet (main droplet) is a part of the positively charged droplet, the ink mist is positively charged. That is, the ink mist is not electrically neutral. Therefore, the ink mist acts as a repulsive force on the positively charged transport belt, and soars (floats) upward in FIG. 3 (on the recording head side).

Next, FIG. 4A is a configuration diagram of the electrostatic adsorption conveyance belt, and FIG. 4B is a diagram illustrating alternating charging in the electrostatic adsorption conveyance belt.
The conveyance belt 131 rotates clockwise as the conveyance roller 132 rotates, and at the same time, by alternately applying a high voltage (square wave) to the charging roller 138, positive and negative charges are alternately applied on the conveyance belt (insulating layer). And an alternating electric field is formed on the conveyor belt (FIG. 4B). When the paper P reaches the conveying belt 131 on which an alternating electric field is formed, the electric charge in the paper is attracted to the electric field on the conveying belt to generate an attracting force.

Next, FIG. 5 is an explanatory diagram of the state of occurrence of ink mist due to charging of the electrostatic adsorption conveyance belt.
Due to the electric field between the transport belt 131 and the head 165 charged positively (+) during electrostatic attraction transport, the ejected ink (main droplet) is charged to a polarity (-) opposite to the belt charge polarity. To do. Therefore, as described with reference to FIG. 3, a positively charged ink mist is generated.
Since the electrostatic adsorption type conveyance belt periodically changes its polarity by alternating charging, a positively charged state and a negatively charged state are alternately generated. For this reason, a situation where positively charged ink mist is generated and a situation where negatively charged ink mist is generated alternately appear according to the change in polarity of the electrostatic adsorption type conveyance belt.

Next, FIG. 6 is a diagram for explaining a print area (a carriage scan area).
The carriage 160 moves in a direction perpendicular to the paper conveyance direction (direction perpendicular to the paper surface of FIG. 6) (left and right direction of the paper surface of FIG. 6) and scans back and forth.
FIG. 6 shows a state in which the carriage 160 is in an intermediate position, and the carriage can move in either the left or right direction within the range of the left and right side plates (recovery member support members) 167 and 168 of the exterior.

Next, FIGS. 7A to 7D are diagrams for explaining airflow generated by scanning the carriage.
In the process in which the carriage 160 moves in the forward direction in the air, the air that is ahead (forward) in the movement direction of the carriage moves from the principle of slipstream to the position (rearward in the movement direction) where the carriage originated. For this reason, the airflow generated by the movement of the carriage is an airflow that flows from the front of the carriage (forward in the moving direction) to the rear of the carriage (opposite to the moving direction).

In FIG. 7 for explaining the air flow generated by the scanning of the carriage, when the carriage moves in the forward path (left direction) as shown in FIGS. 7A and 7B, for example, the paper P moves from right to left. In the process, ink mist (floating droplets) sequentially accumulates on the right back side of the carriage, and the mist amount becomes maximum when the carriage is at the left end of the scanning range.
This is because as the carriage moving in the forward direction approaches the side plate 167 on the forward path side, the ink mist existing ahead in the movement direction of the carriage is sent to the separation direction (direction of the side plate 168 on the return path side) by the slip stream. It is a phenomenon that occurs to come. As a result, as the carriage moves away from the return path side plate 168, the amount of ink mist in a floating state increases in the space in the separation direction (return path side space). In the present invention, an electric field is generated by increasing the voltage to the ink mist collecting member 210 on the return path so as to respond to the increase in the amount of mist. Thereby, the increased mist can be efficiently sucked and adsorbed.

  Conversely, as shown in FIGS. 7C and 7D, when the carriage moves in the return path (rightward), the ink mist sequentially moves from the left to the right on the sheet P in the process of moving the left posterior side of the carriage ( The amount of mist becomes maximum when the carriage is at the right end of the scanning range. The electric field is generated by raising the voltage to the ink mist collecting member 200 on the forward path side in response to the increase in the mist amount.

<Embodiment for Leakage Current Detection>
Next, FIG. 8A is a diagram for explaining a configuration example in which the ink mist collection member (collection member) according to one embodiment of the present invention is arranged on the left and right side plates of the exterior, and FIGS. It is a figure explaining the principle which a short generate | occur | produces. FIG. 8A also shows the state where the ink mist floats and the arrangement of the ink mist collection member.
The apparatus 100 for ejecting liquid according to the present embodiment includes a liquid ejection head 165 that ejects liquid, and a forward path side wall 167 and a return path that are located on both sides of the carriage movement direction in order to collect floating liquid when a voltage is applied. The configuration includes ink mist recovery members (recovery members) 200 and 210 disposed on the side wall 168, and leakage current detection means 300 for detecting leakage current from each recovery member.

More specifically, the apparatus 100 for discharging liquid includes a carriage 160 that includes a liquid discharge head 165 and reciprocates, a drive source (motor) that reciprocates the carriage, a discharge operation by the liquid discharge head, and / or Recovery members 200 and 210 that are disposed at a position corresponding to the airflow including the floating liquid generated by the movement of the carriage (appropriate place where the floating liquid is easily captured) and actuate when a voltage is applied to collect the floating liquid; Control means 222 and 223 for controlling voltage application (on / off switching, voltage value, polarity, on / off timing, etc.) to the recovery member in accordance with the operation of the liquid ejection head and / or carriage, and leakage current from each recovery member And a leakage current detecting means 300 for detecting.
The collecting members 200 and 210 are arranged at positions corresponding to the air current so that the generated ink mist moves along with the air current so as to easily suck and capture the floating ink mist.

In the image forming unit 101 of the ink jet printer 100 according to this embodiment, the ink mist collecting member 200 (electrode) on the forward path side is disposed along the left side plate 167 facing the carriage at the end position (left end position) of the carriage 160 in the forward path direction. In addition, a return path ink mist collecting member (electrode) 210 is disposed along the right side plate 168 facing the carriage at the return path end position (right end position) of the carriage 160. The carriage 160 is configured to face the ink mist collecting members 200 and 210 at a predetermined positional relationship (a predetermined distance) at each end position of the forward path and the backward path.
Ink mist collection members (collection members) are arranged at least in two places according to the moving direction of the carriage. In this example, since the carriage scans along the linear reciprocating path, each ink mist collecting member is disposed along both ends of the reciprocating path.

Further, each ink mist collecting member is disposed in the vicinity of the forward side wall 167 and the backward side wall 168, whose positional relationship with the carriage changes as the carriage moves.
The ink mist collecting member is a conductive metal (electrode) such as a sheet metal, for example, and adsorbs floating droplets (ink mist) with an electrostatic force by applying a voltage to the sheet metal to be charged.

  By the way, as shown in FIG. 7, the ink mist flies (floats) in the aircraft in the airflow generated by the movement of the carriage. In addition, the ink mist is charged in a state where only the positively charged ink mist is generated because the transport belt 131 is positively charged, and in the negative state because the transport belt is negatively charged. There are two possible cases. Thus, since the ink mist may be positively charged or negatively charged, one recovery member 200 is constituted by a positive charge member 200P and a negative charge member 200M, and the other recovery member 210 is It comprises a positive charging member 210P and a negative charging member 210M. That is, the recovery members 200 and 210 according to the present embodiment include charging members 200P and 210P that are positively charged when a voltage is applied, and charging members 200M and 210M that are negatively charged when a voltage is applied. It has.

  As the ink mist is collected by the collecting members 200 (200P, 200M) and 210 (210P, 210M), the amount of ink deposited on the surface of each collecting member increases. Since the ink is conductive, as the amount of deposition increases, it accumulates in a bridge shape across two recovery members (200P and 200M, 210P and 210M) with different charging polarities as shown in FIG. When a voltage is applied to the charging member, a leakage current flows to the other charging member via the deposited ink.

  Specifically, as shown in FIG. 8A, when each of the collecting members 200 and 210 has a configuration in which the positive charging members 200P and 210P and the negative charging members 200M and 210M are arranged adjacent to each other, FIG. As shown in FIG. 8B, the ink is deposited across the two charging members that are oppositely charged. As a result, a short circuit (short circuit between the opposite poles) occurs between the positive charging member 200P and the negative charging member 200M and between the positive charging member 210P and the negative charging member 210M (FIG. 8B). Current flow indicated by arrow A1 in the middle). This short-circuit between the opposite poles generated through the accumulated ink causes a malfunction due to a leak current that flows from the positive charging member side to the negative charging member side or vice versa, and sucks ink mist. The electric potential of the charging member is lowered, resulting in a reduction in recovery capability. In other words, if a leakage current flows between two charging members that are oppositely charged (between 200P and 200M, and between 210P and 210M), the charging member cannot be charged to the target potential. The collection capacity is reduced.

In addition, the problem of leakage current due to the collected recovery ink also occurs between the recovery members and the metal side plates (recovery member support members) 167 and 168. That is, the recovery member and the side plate (sheet metal) need to be insulated from each other, but the collected recovery ink (ink resistance) is brought into conduction between the recovery member and the side plate in FIG. 8B. A leakage current as indicated by an arrow A2 is generated, and when a voltage is applied and charged, the potential of the collecting member that sucks the ink mist is lowered, and the collecting ability is lowered.
The problem of leakage current between the recovery member and the side plate is not limited to the case where the positive and negative charging members are arranged adjacent to each other (separately arranged), and the side plates 167 and 168 are charged to one polarity as shown in FIG. This also occurs when only one charging member 215 (collecting member) is arranged. That is, in the example of FIGS. 8A and 8B, the two recovery members 200 and 210 are each composed of two charging members that are charged positively and negatively, respectively. However, as shown in FIG. May be composed of a single charging member 215 that charges only one of the polarities. In this case, there is a problem that the ink accumulated between the charging members 215 and the side plates causes a short circuit between the charging members 215 and the side plates, as indicated by the current flow of the arrow A3.

  When a conductive state (conductive state due to the resistance of the ink) occurs between the charging members that are charged adjacently on the same side plate side and charged to different polarities, or between the charging member and the side plate, one charging member Even when a voltage is applied, the other oppositely charged charging member or a current flowing through the side plate (leakage current is generated) and the charging member performing the ink mist suction operation are sufficiently charged. It will not be done. If the charging member is not sufficiently charged, the mist collecting ability is lowered.

Next, FIG. 9 is a block diagram illustrating a configuration example for applying a voltage to the ink mist collecting member.
Since the electric field generated by the ink mist recovery members (recovery members, charging members) 200 and 210 increases in proportion to the applied voltage, an output voltage generation substrate (control means) 223 that generates a voltage for forming the electric field. A voltage is generated at.
The power supplied from the AC power supply 220 to the control board (control means) 222 via the PSU 221 is supplied to the output voltage generation board 223 and used as power (voltage) for charging the ink mist collecting members 200 and 210. . The control board 222 supplies a control signal (output ON / OFF signal) for turning ON / OFF the output voltage to the ink mist collecting member to the output voltage generation board 223, and the output voltage generation board 223 outputs the control signal. Based on the above, the voltage application to each ink mist collecting member is turned ON / OFF.
At this time, the timing for turning on / off the output voltage may be, for example, an operation of ON for collecting mist during printing and OFF during non-printing.

FIG. 10 is a circuit configuration diagram for realizing a method of detecting the leakage current amount of the ink mist collecting member. The same parts as those in FIG.
In FIG. 10, a leakage current amount detection circuit 310 as the leakage current detection means 300 is mounted on the output voltage generation substrate 223, and a leakage current amount (leakage current value) generated when a voltage is applied to the ink mist collection members 200 and 210. ) Is detected by the leakage current amount detection circuit 310.
Specifically, a series resistor 312a is inserted in series between the voltage generation circuit 225 and the ink mist collecting members 200 and 210, and a voltage difference generated by a leak current flowing through the resistor 312a is divided into resistors (resistors 312b, 312b, 312c) and a voltage dividing resistor (resistors 312d, 312e) are observed by the AD converter 314, thereby detecting a leakage current amount of the ink mist collecting member as a voltage difference generated at both ends of the series resistor 312a. When a leak current is generated, a leak current flows from the voltage generation circuit 225 to the recovery member via the series resistor 312a, so that a potential difference is generated between both ends of the series resistor 312a.
That is, the current threshold value for determining the amount of leakage current is determined based on the voltage applied to the ink mist collecting member and the resistance value of the ink to be used.
From the CPU of the control board, the AD conversion value of the AD converter is read to detect the leakage current amount.

Next, FIG. 11 is a flowchart showing an operation flow in detecting the leakage current amount.
When no current leakage occurs between the collection members (charging members) or between the collection members and the side plates, the voltage application mode to the collection members is set to the normal mode (normal voltage application mode) (step S1).
When the control board 222 receives the detection signal indicating the leakage current value from the leakage current amount detection circuit 310, the control board is recorded in advance in the ROM shown in FIG. 2 based on the detection signal. It is determined which threshold value the leak current value exceeds by referring to an arbitrary plurality of current threshold values (leakage current threshold values). When the control board determines that the leakage current exceeds the first threshold value having the lowest threshold value, it determines that correction is necessary for the voltage application control, and changes to the correction mode (steps S2, S3 Yes, S4). In the correction mode, the voltage application to the recovery member is continued for a predetermined time even after the printing operation is completed (during non-printing), or the recovery time is lengthened or applied to the recovery member as compared with the case where no leak current is generated. The voltage value is increased by a predetermined value to compensate for the potential that decreases due to the leakage current. The voltage application in the correction mode is continued as long as the leakage current exceeding the first threshold (<second threshold) continues to be detected.

Further, when it is determined that the leakage current value has exceeded the second threshold value, which is the second highest threshold value after the first threshold value, it is determined that correction of the applied voltage is insufficient and maintenance of the recovery member is necessary. Maintenance is urged to the user by using the display means (notification means) that does not (step S3 No, S5 Yes, S6). In the maintenance, the apparatus is stopped to clean and remove ink accumulated on the surface of the collecting member, between the collecting members, and between the collecting member and the side plate.
Similarly, if the third threshold value, which is a threshold value higher than the second threshold value, is exceeded, it is determined that the recovery member or the voltage generation circuit 223 has failed, and the user is notified that there is a possibility of failure. Repair is urged (S5 No, S7 Yes).
Each threshold has a relationship of first threshold <second threshold <third threshold.

  As described above, in the apparatus for ejecting liquid according to the present invention, control for taking a corresponding measure for maintaining or recovering the recovery capability of the floating liquid by the recovery member according to the leak current value detected by the leak current detection means 300. I do. As countermeasures for this, applied voltage correction control for correcting or maintaining the recovery capability by correcting the voltage application control method to the recovery member, and notification control for determining whether maintenance is necessary or whether there is a failure and notifying the outside , At least.

  In the method for controlling a device for discharging a liquid according to the present invention, a liquid discharge head for discharging a liquid, a recovery member for recovering floating liquid when a voltage is applied, and a leakage current value (presence / absence) from the recovery member , Amount) and a control means for controlling them, and the control means controls the ON / OFF of the voltage application to the recovery member in accordance with the discharge operation of the liquid discharge head. According to the leakage current value detected by the current detection means, control is performed to take corresponding measures to maintain or recover the floating liquid recovery capability of the recovery member.

FIG. 12 is a diagram for explaining a response method (response measure) according to the amount of leakage current.
A table related to the amount of leakage current based on the collection member and the amount of ink mist deposited on the side plate (sheet metal) supporting the collection member and the number of printed sheets is prepared in the ROM, and the leakage current amount detection circuit 310 actually detects it. The region division of how to deal with the amount of leak current is set as shown in FIG. That is, while the leakage current increases as the ink mist amount increases, the ink mist amount increases as the number of printed sheets increases. For this reason, the applied voltage and the applied time are determined if the accumulated amount of ink mist detected from the leakage current value and / or the accumulated amount (leakage current value) predicted by the number of printed sheets exceeds the first threshold. Is corrected and output. If the second threshold value is exceeded, a message indicating that maintenance is required is displayed. If the third threshold value is exceeded, a failure is determined (a failure is displayed).
In FIG. 12, within a range in which the amount of leakage current does not reach the failure level (third threshold), the area is divided into a normal area, an applied voltage correction area (including application time correction), and a maintenance area. On the other hand, when the leakage current amount exceeds the third threshold value, it becomes a failure determination area.
That is, as shown in the flowchart of FIG. 11, when it is determined that the applied voltage (including the application time) needs to be corrected, the voltage application mode is automatically switched to the voltage application correction mode, and it is determined that maintenance or repair is necessary. If so, notify the user.

Next, FIG. 13 is a flowchart showing a control procedure according to the voltage application correction mode (1).
The voltage application to the ink mist collecting member is executed by controlling the output voltage with the output ON / OFF control signal from the control board 222 shown in FIG.
In this voltage application correction mode, even when the ink is not ejected, if the correction mode is ON (if the amount of leakage current exceeds the first threshold), even after printing is stopped The output voltage is turned on until an arbitrarily set time elapses, thereby performing control to supplement the recovery capability of the mist recovery member.

That is, if the ink is being ejected (Yes) in step S11, the output voltage is turned on in step S12, the ink is not being ejected (No), and the correction mode is turned on (Yes) in step S13. The output voltage is turned on (step S14), and the output voltage is turned off when a predetermined set time has elapsed (steps S15 and S16). If the correction mode is not set in step S13, the output voltage is turned OFF simultaneously with the stop of ink ejection.
By turning on the output voltage even after printing is stopped (during non-printing), the ink mist flying when not printing (ink mist that could not be collected during printing) is collected by charging the collecting member. The total collection capacity can be increased.

Next, FIG. 14 is a flowchart showing a control procedure according to the voltage application correction mode (2).
Due to an increase in leakage current between the recovery members or between the recovery member and the side plate, a target voltage is not applied to the recovery member that is operating for ink mist recovery, so that the mist recovery capability is reduced.
In this voltage application correction mode, a power-up mode is executed in which the voltage generated by the output voltage generation substrate 223 is increased compared to the normal voltage when the leakage current value is in the applied voltage correction region exceeding the first threshold. As a result, the voltage applied to the recovery member is pulled up to the same level as in normal times, and control is performed to supplement the mist recovery capability. That is, control is performed to restore the suction force due to charging of the recovery member to the normal level by applying a voltage higher than the normal applied voltage to the recovery member by the amount of the voltage that has been reduced due to the occurrence of the leak current.
That is, when the correction mode is turned ON during ink ejection in step S21, a power-up voltage is generated and applied to the recovery member (steps S22 and S23). When the correction mode is OFF in step S22, a normal voltage is applied to the recovery member (step S25).

FIG. 15 is a diagram illustrating an example of a circuit configuration for realizing the power-up mode control method. The same parts as those in FIG. 9 will be described with the same reference numerals.
In this example, two types of output voltage generation circuits 225a and 225b are mounted on the output voltage generation board 223 in parallel, for example, and the output voltage generation circuits 225a and 225b are enabled by the CPU of the control board 222 ( By alternately switching between valid / invalid), the generated voltage can be divided into two types, a normal voltage and a power-up voltage.
As a result, two types of voltages to be applied to the mist collecting member are generated and changed according to the state of the leakage current of the collecting member.
However, when a plurality of correction modes are prepared in the output voltage generation circuit 225b for power-up voltage, the output voltage of the output voltage generation circuit is controlled by a multi-bit power-up signal, or the voltage data is obtained from the CPU. It is necessary to change the output voltage in multiple stages by inputting to the DA converter.

<Modified Embodiment Regarding Location of Collecting Member>
FIGS. 16A, 16B, and 16C are diagrams showing a configuration example in which the ink mist collecting member is arranged at a place other than the side plate.
In the above-described embodiment, an example in which each collecting member is arranged near the left and right side plates is shown, but the arrangement position of the ink mist collecting member is not limited to the left and right side plates. As long as the ink mist can be collected, the ink mist may be disposed on the carriage or in any part of the exterior.
In other words, the ink mist collecting member 216 may be provided at an appropriate position of the carriage 160 itself as shown in FIGS. That is, FIG. 16A shows an example provided on one side surface of the carriage in the moving direction, and FIG. 16B shows an example provided on both side surfaces of the carriage 160 in the moving direction. Further, although not shown, a collecting member may be provided on the top surface, bottom surface, front hand surface, back side surface, corner portion, etc. of the carriage. That is, as long as the ink mist can be efficiently captured in consideration of the flow of ink mist, the ink mist may be disposed at any part of the carriage.

Or you may provide in the top | upper surface of an exterior like the figure (c), and may provide in the near side board orthogonal to the right and left side boards of an exterior, or a back side board. That is, as long as the ink mist can be efficiently captured in consideration of the flow of ink mist, the ink mist may be disposed at any part of the exterior.
As described above, even when the collecting member is provided at a place other than the left and right side plates, the ink mist flying in the air can be efficiently sucked and adsorbed by charging the collecting member.

<Summary of composition, action and effect of invention>
The apparatus for ejecting liquid according to the first aspect of the present invention includes a liquid ejection head 165 that ejects liquid, collection members 200 and 210 that collect floating liquid when a voltage is applied, and a leakage current value from the collection member ( Leak current detecting means 300 for detecting presence / absence and amount).
When floating liquid (including dried liquid) adheres and accumulates on the collecting member (charging member), when a voltage is applied to the collecting member to be operated, the collecting member and the side plate (collecting member support member) Leakage current is generated through the deposited liquid, and it becomes difficult to secure a sufficient voltage for collecting the floating liquid. Accordingly, by appropriately detecting the presence or absence and value of the leakage current, it is possible to take countermeasures for maintaining and recovering the recovery capability of the recovery member.
In other words, the amount of leakage current when a voltage is applied to the recovery member is detected to determine whether maintenance is necessary or whether there is a failure, or the voltage application control method is corrected according to the amount of leakage current to improve the ink mist recovery capability. It can be prevented from lowering.

According to a second aspect of the present invention, there is provided an apparatus for ejecting liquid, comprising a carriage that includes a liquid ejection head and reciprocates, and the recovery member is disposed at a position corresponding to an airflow generated by the movement of the carriage. To do.
Since the floating liquid floats on the airflow generated by the movement of the carriage, efficient recovery can be performed by disposing the recovery member in the airflow moving path, the moving direction, and the like.

In the apparatus for ejecting liquid according to the third aspect of the present invention, the recovery member includes a charging member that is positively charged when a voltage is applied, and a charging member that is negatively charged when a voltage is applied. Features.
When the conveyance belt that conveys the recording medium on which the droplets ejected from the liquid ejection head land is alternately charged, the floating liquid separated from the droplets is alternately charged positively and negatively.
Correspondingly, one recovery member can be constituted by a positive charging member and a negative charging member. In this case, a leakage current is generated by depositing a floating liquid having conductivity across both charging members. As a means for detecting such a leakage current, the leakage current detection means 300 functions effectively.

According to a fourth aspect of the present invention, there is provided a device for ejecting a liquid, which is a countermeasure for maintaining or recovering the recovery capability of the floating liquid by the recovery member in accordance with the leak current value detected by the leak current detecting means. As countermeasures, correct the voltage application control method to the recovery member to maintain or recover the recovery capability, and determine the necessity of maintenance and the presence or absence of failure. It includes at least notification control for notification to the outside.
By taking the most appropriate measures according to the value of the leakage current, the recovery capability can be maintained and supplemented, and the ink mist recovery system can be operated as intended. As applied voltage correction control, after printing is completed, even during non-printing, the required voltage is applied to the recovery member to extend the recovery time, thereby maintaining or recovering the voltage that has been reduced due to leakage current. There is also a method of applying a high voltage to maintain and recover the voltage lowered by the leakage current. If the leakage current value is so large that the applied voltage correction cannot compensate for the decrease in the liquid recovery capability, the user is informed that the maintenance should be performed or that the repair should be performed due to a malfunction.

In the apparatus for ejecting liquid according to the fifth aspect of the present invention, in the applied voltage correction control, when the leakage current value detected by the leakage current detection means exceeds a predetermined threshold, the output is performed for a predetermined time after the end of the printing operation. Control is performed to turn on the voltage.
According to this, the mist collection capability weakened by the leak current can be supplemented.

In the apparatus for ejecting a liquid according to the sixth aspect of the present invention, in the applied voltage correction control, when the leak current value detected by the leak current detection means exceeds a predetermined threshold, the normal time (when no leak occurs) Control is performed to apply a voltage higher than the applied voltage to the recovery member.
According to this, the mist collection capability weakened by the leak current can be supplemented.

In the control method of the apparatus for ejecting liquid according to the seventh aspect of the present invention, the liquid ejection head for ejecting the liquid, the recovery member for recovering the floating liquid when a voltage is applied, and the leakage current value from the recovery member (presence / absence) , Amount) and a control means for controlling them, and the control means controls the ON / OFF of the voltage application to the recovery member in accordance with the discharge operation of the liquid discharge head. Control is performed to take a countermeasure to maintain or recover the floating liquid recovery capability of the recovery member according to the leak current value detected by the current detection means.
By taking the most appropriate measures according to the value of the leakage current, the recovery capability can be maintained and supplemented, and the ink mist recovery system can be operated as intended.

According to an eighth aspect of the present invention, there is provided an image forming apparatus comprising the device for discharging a liquid according to any one of the first to sixth aspects.
According to this image forming apparatus, even when the recovery member that recovers the floating liquid generated by the operation of the carriage and the recording head cannot exhibit sufficient recovery capability due to the leakage current, the applied voltage is reduced. By controlling, informing the user of the need for maintenance or repair due to failure, it is possible to efficiently recover and recover the recovery capability.

DESCRIPTION OF SYMBOLS 100 ... Inkjet printer (image forming apparatus) 101 ... Image forming part, 120 ... Paper feed part, 124 ... Separation pad, 130 ... Conveying part, 130 ... Paper conveying part, 131 ... Conveying belt, 132 ... Conveying roller, 133 ... Tension roller, 135 ... transport guide, 136 ... tip pressure roller, 138 ... charging roller, 140 ... discharge section, 141 ... separation claw, 142 ... discharge roller, 143 ... discharge tray, 160 ... carriage, 165 ... recording Head (liquid discharge head), 165A, 165B ... recording head, 167 ... side plate, 168 ... side plate, 200 ... ink mist collecting member (collecting member), 200P, 200M, 210P, 210M ... charging member, 210 ... ink mist collecting member (Collection member), 220 ... AC power supply, 221 ... PSU, 222 ... control board (control means), 23 ... output voltage generating substrate (control means), 225,225a, 225b ... voltage generation circuit, 230 ... scan encoder sensor, 231 ... voltage control unit, 300 ... leakage current detecting means, 310 ... leakage current detecting circuit.

JP 2013-060023 A

Claims (8)

A liquid discharge head for discharging liquid;
A collecting member for collecting floating liquid when voltage is applied;
A leakage current detection means for detecting a leakage current value from the recovery member;
A device for ejecting liquid, comprising: A carriage that reciprocates with the liquid ejection head;
The apparatus for ejecting liquid according to claim 1, wherein the recovery member is disposed at a position corresponding to an airflow generated by movement of the carriage.   The liquid according to claim 1, wherein the recovery member includes a charging member that is positively charged when a voltage is applied, and a charging member that is negatively charged when a voltage is applied. Discharge device. In accordance with the leakage current value detected by the leakage current detection means, control to take a countermeasure for maintaining or recovering the recovery ability of the floating liquid by the recovery member,
As the countermeasure, the voltage application control method for correcting the voltage application to the recovery member is corrected to maintain or recover the recovery capability, and the necessity of maintenance or the presence / absence of failure is determined and notified to the outside. The apparatus for discharging a liquid according to any one of claims 1 to 3, comprising at least notification control.   In the applied voltage correction control, when the leak current value detected by the leak current detection unit exceeds a predetermined threshold, control is performed to turn on the output voltage for a predetermined time even after the end of the printing operation. An apparatus for discharging a liquid according to claim 4.   In the applied voltage correction control, when the leak current value detected by the leak current detection means exceeds a predetermined threshold, control is performed to apply a voltage higher than the normal applied voltage to the recovery member. The apparatus for ejecting liquid according to claim 4. A liquid discharge head that discharges liquid; a recovery member that recovers floating liquid when a voltage is applied; a leak current detection means that detects a leak current value from the recovery member; and a control means that controls these. A control method of a device for discharging a provided liquid,
The control means includes
ON / OFF control of voltage application to the recovery member according to the discharge operation of the liquid discharge head,
Control of a device for ejecting liquid, wherein control is performed to take a countermeasure for maintaining or recovering the recovery capability of the floating liquid by the recovery member in accordance with a leak current value detected by the leak current detection means Method.   An image forming apparatus comprising the device for discharging a liquid according to claim 1.

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