JP2019001035A - Device for discharging liquid - Google Patents

Abstract

A droplet discharge state is accurately detected. A liquid discharge head 41 that discharges liquid and an electrode plate 101 that receives liquid discharged from the liquid discharge head 41 and detects an electrical change caused by the liquid. When one or both of 101 moves in a direction crossing the liquid discharge direction, the distance between the liquid discharge head 41 and the electrode plate 101 in the liquid discharge direction changes. [Selection] Figure 9

Description

  The present invention relates to an apparatus for discharging a liquid.

  As an apparatus for ejecting liquid, for example, an image forming apparatus such as a printer, a facsimile, a copying apparatus, and a complex machine of these is known. As an image forming apparatus, an apparatus including a liquid discharge head (hereinafter also simply referred to as a head) is used to convey a recording medium (hereinafter also referred to as “paper”, but the material is not limited) and liquid. Inkjet image forming apparatuses are known that perform image formation (recording, printing, printing, and printing are also used synonymously) by adhering the ink (recording liquid) to the recording medium.

  In addition, in order to detect the droplet discharge state from the head of such an ink jet image forming apparatus, droplets are discharged from the head toward the electrode plate, and the electricity when the droplet lands on the electrode plate. It is known to detect ejection / non-ejection by measuring a change in the target.

  In this way, when the droplet discharge state is detected by measuring the electrical change when the droplet lands on the electrode plate, the detection discharge droplet length (liquid length) is discharged on the electrode plate. It is known that the measurement accuracy is improved by setting the distance between the head and the electrode plate to an optimum value. For this reason, it is known that the ejection for detection is performed using a dedicated waveform so that the droplet length is constant.

  For example, in Patent Document 1, when the detection performance is reduced due to adhesion of fixed ink or the like to the electrode plate, the inspection accuracy is maintained regardless of the adhesion state of the deposit by adjusting the height of the electrode plate. A nozzle inspection device that can be used is disclosed.

  However, in the detection of the droplet discharge state so far, since the dedicated waveform is used for detection of the droplet discharge state, the discharge is different from the drive waveform at the time of actual printing (also called the print waveform). Therefore, there is a case where a mismatch occurs between the detection result and the discharge result at the time of actual printing.

  Also, there are multiple print waveforms depending on the print mode of the image forming apparatus (for example, a mode that prioritizes productivity (high-speed mode, a mode that prioritizes image quality, etc.)) and the type of paper. Since the droplet lengths are different, there is a problem that it is difficult to set the distance between the head and the electrode plate to an optimum value.

  Accordingly, an object of the present invention is to provide an apparatus for ejecting a liquid that can easily adjust the distance between a head and an electrode plate and can accurately detect a droplet ejection state.

  In order to achieve this object, an apparatus for ejecting liquid according to the present invention includes a liquid ejection head that ejects liquid, and an electrode that receives the liquid ejected from the liquid ejection head and detects an electrical change caused by the liquid. And either one or both of the liquid discharge head and the electrode member move in a direction intersecting the liquid discharge direction, whereby the liquid of the liquid discharge head and the electrode member The interval in the discharge direction changes.

  According to the present invention, it is possible to accurately detect the droplet discharge state.

2 is a plan view illustrating a mechanism unit of an image forming apparatus that is an embodiment of an apparatus that discharges liquid. FIG. FIG. 2 is a side view illustrating a main part of the image forming apparatus. 3 is a plan view of a liquid discharge unit of the image forming apparatus. FIG. 3 is a block explanatory diagram of a control unit of the image forming apparatus. FIG. It is explanatory drawing of a discharge detection apparatus. It is a flowchart of the gap adjustment control of a head and an electrode plate. It is explanatory drawing which shows an example of the printing waveform according to a paper kind and printing mode, drop length, and a head electrode plate gap. It is a flowchart of discharge detection control. It is explanatory drawing (1) of the 1st structural example of a gap adjustment mechanism. It is explanatory drawing (2) of the 1st structural example of a gap adjustment mechanism. It is explanatory drawing (1) of the 2nd structural example of a gap adjustment mechanism. It is explanatory drawing (2) of the 2nd structural example of a gap adjustment mechanism.

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

  The apparatus for ejecting liquid according to the present embodiment includes a liquid ejection head (liquid ejection head 41) that ejects liquid and an electrode member (electrode) that receives the liquid ejected from the liquid ejection head and detects an electrical change due to the liquid. Plate 101), and either or both of the liquid discharge head and the electrode member move in a direction intersecting the liquid discharge direction, whereby the distance between the liquid discharge head and the electrode member in the liquid discharge direction. Is something that changes. In addition, the code | symbol in embodiment and an application example are shown in a parenthesis.

  An ink jet image forming apparatus, which is an embodiment of an apparatus for ejecting liquid according to the present invention, will be described with reference to FIGS. FIG. 1 is an explanatory plan view of a mechanism part of the image forming apparatus, FIG. 2 is an explanatory side view of a main part of the image forming apparatus, and FIG. 3 is an explanatory plan view of a liquid discharge unit of the image forming apparatus. Note that FIG. 3 shows the head transmitted from above.

  This image forming apparatus is a serial type apparatus, and a carriage 3 is held by a guide mechanism such as a main guide member 1 so as to be movable in the main scanning direction. The carriage 3 is reciprocated in the main scanning direction (carriage moving direction) by a main scanning motor 5 constituting a main scanning moving mechanism via a timing belt 8 spanned between the driving pulley 6 and the driven pulley 7.

  On the carriage 3, two liquid discharge units 40A and 40B (referred to as “liquid discharge unit 40” when not distinguished) are mounted. The liquid discharge unit 40 is configured by integrating a liquid discharge head 41 as liquid discharge means and a head tank 42 that supplies liquid to the liquid discharge head 41.

  As shown in FIG. 3, the liquid discharge head 41 has two nozzle rows Na and Nb in which a plurality of nozzles 41n are arranged. One nozzle row Na of the head 41 of the liquid discharge unit 40A discharges black (K) droplets, and the other nozzle row Nb discharges cyan (C) droplets. Further, one nozzle row Na of the head 41 of the liquid discharge unit 40B discharges magenta (M) droplets, and the other nozzle row Nb discharges yellow (Y) droplets.

  In addition, as a liquid discharge means, what is equipped with the several nozzle row | line | column which discharges the droplet of each color which arranged the several nozzle in the nozzle surface 41a of one liquid discharge head etc. can also be used.

  The head tank 42 is configured to include a plurality of tank portions corresponding to the two nozzle rows Na and Nb of each head 41, each paired with two tank portions that store liquids of respective colors.

  On the apparatus main body side, a cartridge holder 51 to which a main tank (liquid cartridge) 50 (50y, 50m, 50c, 50k) containing liquid of each color is replaceably mounted is disposed.

  The cartridge holder 51 is provided with a liquid feed pump unit 52, and each color is supplied from the main tank 50 to the tank portion of each head tank 42 through a supply tube (also referred to as a liquid supply path) 56 of each color by the liquid feed pump unit 52. Liquid is supplied.

  On the other hand, in order to transport the paper P, a transport belt 12 that is a transport means for sucking the paper P and transporting the paper P at a position facing the head 41 of the liquid discharge unit 40 is provided.

  The conveyor belt 12 is an endless belt and is stretched between the conveyor roller 13 and the tension roller 14.

  The conveyance belt 12 rotates in the sub-scanning direction when the conveyance roller 13 is rotationally driven by the sub-scanning motor 16 via the timing belt 17 and the timing pulley 18. The conveyor belt 12 is charged (charged) by a charging roller while moving around, or the sheet P is sucked by a suction unit.

  Further, on one side of the carriage 3 in the main scanning direction, a maintenance / recovery mechanism 20 which is one of recovery means for maintaining / recovering the head 41 is disposed on the side of the transport belt 12. On the other side of the carriage 3 in the main scanning direction, idle discharge receivers 81 for receiving liquid preliminarily discharged (empty discharge) from the head 41 are arranged on the sides of the conveyance belt 12. The discharge for maintaining and recovering the head state is called preliminary discharge, and the discharge for achieving the original purpose of the apparatus is called main discharge.

  The maintenance / recovery mechanism 20 includes, for example, a suction cap 21 for capping the nozzle surface 41a of the head 41, a moisturizing cap 22, a wiper member 23 for wiping the nozzle surface 41a, and an empty discharge receiver 24 for receiving a spare liquid. .

  Further, in a region outside the recording region between the conveyance belt 12 and the maintenance / recovery mechanism 20 and capable of facing the head 41, a discharge detection unit 100 constituting a discharge detection device that detects the discharge state of the head 41 is provided. Has been placed.

  In addition, an encoder scale 123 having a predetermined pattern is stretched between both side plates along the main scanning direction of the carriage 3, and an encoder sensor 124 formed of a transmission type photosensor that reads the pattern of the encoder scale 123 is provided on the carriage 3. Provided. These encoder scale 123 and encoder sensor 124 constitute a linear encoder (main scanning encoder) that detects the movement of the carriage 3.

  Further, a code wheel 125 is attached to the shaft of the transport roller 13 and an encoder sensor 126 including a transmission type photo sensor for detecting a pattern formed on the code wheel 125 is provided. These code wheel 125 and encoder sensor 126 constitute a rotary encoder (sub-scanning encoder) that detects the amount and position of movement of the conveyor belt 12.

  In the apparatus configured as described above, the paper P is fed onto the transport belt 12 and sucked, and is transported in the sub-scanning direction by the circumferential movement of the transport belt 12.

  Therefore, by driving the head 41 according to the image signal while moving the carriage 3 in the main scanning direction, liquid is ejected onto the stopped paper P to record one line. Then, after the sheet P is conveyed by a predetermined amount, the next line is recorded.

  Upon receiving a recording end signal or a signal that the trailing edge of the paper P reaches the recording area, the printing operation is terminated, and the paper P is discharged onto a paper discharge tray (not shown).

  Next, an overview of the control unit of the image forming apparatus will be described with reference to FIG. FIG. 4 is a block diagram of the control unit of the image forming apparatus.

  The control unit 500 includes a CPU 501 that controls the entire apparatus, a ROM 502 that stores fixed data such as various programs including a program according to the present invention executed by the CPU 501, and a RAM 503 that temporarily stores image data and the like. A control unit 500A is provided.

  In addition, the control unit 500 includes a rewritable nonvolatile memory (NVRAM) 504 for holding data while the apparatus is powered off, image processing for performing various signal processing, rearrangement, and the like on image data. In addition, an ASIC 505 for processing input / output signals for controlling the entire apparatus is provided.

  The control unit 500 includes a data transfer unit for driving and controlling the head 41, a print control unit 508 including a driving signal generating unit, and a head driver (driver IC) provided on the carriage 3 side for driving the head 41. 509.

  In addition, the control unit 500 includes a main scanning motor 5 that moves and scans the carriage 3, a sub-scanning motor 16 that rotates the conveyance belt 12, and a motor driving unit 510 that drives the maintenance / recovery motor 556 of the maintenance / recovery mechanism 20. ing. The maintenance / recovery motor 556 drives the moving mechanism (elevating mechanism) 29 and the suction pump 27 that move the caps 21 and 22 and the wiper member 23 of the maintenance / recovery mechanism 20 up and down (advance and retreat).

  The control unit 500 also includes an encoder analysis unit 511 that receives and analyzes detection signals from the main scanning encoder and the sub scanning encoder.

  In addition, the control unit 500 includes a supply system driving unit 512 that drives the liquid feeding pump 54. In addition, the control unit 500 includes a discharge detection unit 515 that performs discharge detection by the discharge detection unit 100.

  The control unit 500 is connected to an operation panel 514 for inputting and displaying information necessary for the apparatus.

  The control unit 500 has an I / F 506 for transmitting and receiving data and signals to and from the host side. A predetermined information is sent from an information processing apparatus such as a personal computer or a printer driver 601 side of the host 600 such as an image reading apparatus. Send and receive data.

  The CPU 501 of the control unit 500 reads and analyzes the print data in the reception buffer included in the I / F 506, performs necessary image processing, data rearrangement processing, and the like in the ASIC 505, and prints the image data. The data is transferred from the unit 508 to the head driver 509.

  The print control unit 508 transfers the above-described image data as serial data, and outputs a transfer clock, a latch signal, a control signal, and the like necessary for transferring the image data and confirming the transfer to the head driver 509.

  The print control unit 508 includes a drive signal generation unit including a D / A converter that converts D / A conversion of drive pulse pattern data stored in the ROM 502, a voltage amplifier, a current amplifier, and the like. A drive waveform composed of one drive pulse or a plurality of drive pulses is generated and output to the head driver 509.

  The head driver 509 selects a driving pulse constituting a driving waveform provided from the print control unit 508 based on image data corresponding to one line of the head 41 input serially, and applies pressure to the pressure generating unit of the head 41. And the head 41 is driven. At this time, by selecting part or all of the pulses constituting the drive waveform or all or part of the waveform elements forming the pulses, for example, dots of different sizes such as large drops, medium drops, and small drops Can be sorted out.

  The I / O unit 513 acquires information from the temperature sensor 572 and other various sensor groups 570 attached to the apparatus, extracts information necessary for controlling the apparatus, and uses it for various controls.

  The control unit 500 includes a gap control unit 516 that controls the gap adjustment mechanism 520 as an adjustment unit that adjusts the distance between the head and the electrode plate (hereinafter also referred to as a head electrode plate gap). Although details of the gap adjusting mechanism 520 will be described later, the main scanning motor 5 and the main scanning encoder that control the main scanning position of the head 41 function as the gap adjusting mechanism 520.

(Discharge detection device)
Next, the discharge detection device 200 in the device that discharges liquid will be described. The discharge detection device 200 shown in FIG. 5 includes a discharge detection unit 100, a discharge detection unit 515, and a main control unit 500A, and detects whether or not liquid is discharged from the nozzle 41n of the head 41.

  FIG. 5 is an explanatory diagram of the discharge detection device 200. The discharge detection unit 100 includes an electrode plate 101 as an electrode member that includes a receiving surface 102 that receives the liquid discharged from the head 41. Here, the surface of the electrode plate 101 is the receiving surface 102. The receiving surface 102 is subjected to water repellency treatment.

  The electrode plate 101 is disposed on the holder member 103. The holder member 103 is an insulating member made of an insulating material such as plastic.

  The electrode plate 101 is a conductive metal plate, and is formed of, for example, SUS304, a copper alloy with Ni plating, or Pd plating.

  The electrode plate 101 is connected to the discharge detection unit 515 via the lead wire 104.

  Next, the discharge detection unit 515 includes a high voltage power source 701 that applies a high voltage VE (for example, 750 V) to the electrode plate 101. The high voltage power source 701 is on / off controlled by the main controller 500A.

  In addition, a band-pass filter (BPF) 702 for inputting a signal associated with an electrical change of the electrode plate 101 when the liquid discharged on the receiving surface 102 of the electrode plate 101 adheres, and an amplifier (AMP) 703 for amplifying the signal. And an AD converter (ADC) 704 for A / D converting the amplified signal. The conversion result of the ADC 704 is input to the main controller 500A.

  When performing the ejection detection operation, the main control unit 500A makes the nozzle surface 41a and the receiving surface 102 of the head 41 face each other, applies a high voltage VE to the electrode plate 101, and places the nozzle surface 41a and the electrode plate 101 between them. Give potential difference. At this time, the nozzle surface 41a of the head 41 is negatively charged, and the electrode plate 101 is positively charged.

  In this state, one drop or a plurality of drops of the detection liquid is ejected from the head 41 for each nozzle.

  At this time, since the discharged liquid droplets are discharged from the nozzle surface 41a of the head 41 charged negatively, the liquid is also negatively charged. When the negatively charged liquid adheres to the receiving surface 102 and approaches the positively charged electrode plate 101, the voltage of the high voltage VE applied to the electrode plate 101 fluctuates slightly.

  Therefore, the fluctuation (AC component) is extracted by the band pass filter 702, amplified by the amplifier circuit 703, A / D converted by the ADC 704, and input to the main controller 500A as a measurement result (detection result).

  Therefore, the main control unit 500A determines whether or not the measurement result (variation) exceeds a preset threshold value, and when the measurement result exceeds the threshold value, the main control unit 500A is discharging (discharge is present, normal discharge is performed). ), And when it does not exceed the threshold, it is determined that there is no ejection (no ejection).

  Here, when ejecting one nozzle at a time, it takes about 0.5 to 10 msec to determine ejection / non-ejection of one nozzle. Therefore, by giving waveforms to be ejected simultaneously to two nozzles, comparing the detection output with two threshold values, when both nozzles are ejected, when one nozzle is not ejected, both are not ejected. The case can also be determined.

  After the determination of ejection / non-ejection for all nozzles is completed, the high voltage VE applied to the electrode plate 101 is turned off.

  In this way, it is possible to detect the presence / absence and state of discharge by detecting an electrical change of the electrode member when the liquid adheres to the receiving surface.

  The discharge detection apparatus 200 includes the gap control unit 516 and the gap adjustment mechanism 520 shown in FIG. 4 in addition to the configuration shown in FIG. Hereinafter, the gap adjustment control and the discharge detection control by the discharge detection device 200 will be described.

  FIG. 6 is a flowchart of the gap adjustment control between the head and the electrode plate in the ejection detection device 200. The gap adjustment control in the discharge detection device 200 is executed when the user changes the paper setting by operating the operation panel 514 or the like. By executing this at the time of paper setting, it is possible to reduce downtime due to ejection detection. For example, in an image forming apparatus that uses roll paper (continuous paper) as the paper P, the paper type is set as part of the roll forming operation. At that time, gap adjustment control is also executed, thereby reducing downtime. can do.

  First, when the paper type setting is changed by the user (S101), the gap control unit 516 determines whether or not the print paper is properly used according to the print mode for the set paper type, that is, according to the print mode. It is determined whether the print waveform is present (S102).

  Here, the proper use of the print waveform in the print mode will be described. Inkjet image forming apparatuses generally have a mode that prioritizes productivity by reducing the number of scans (productivity priority mode) and a mode that prioritizes image quality by increasing the number of scans (image quality priority mode). ing. In the productivity priority mode, it is necessary to enlarge the area where the paper surface is filled with ink in one scan, so a print waveform with a large drop amount is used. On the other hand, in the image quality priority mode, the paper surface is inked in one scan. Since it is necessary to reduce the area to be filled with, a printed waveform that reduces the amount of drops is used. Further, in the case of a printing waveform with a large amount of droplets, the droplet length becomes long, and in the case of a printing waveform with a small amount of droplets, the droplet length becomes short.

  On the other hand, some paper types have the same print waveform, and some of them can handle both the productivity priority mode and the image quality priority mode by adjusting the number of scans. For this reason, in such a paper type, the print waveform is not properly used depending on the print mode.

  FIG. 7 is an explanatory diagram illustrating an example of a print waveform, a drop length, and a head electrode plate gap according to the paper type and print mode.

  In the example shown in FIG. 7, in the case of coated paper, the print waveform (print waveform B) in the productivity priority mode is different from the print waveform (print waveform C) in the image quality priority mode. The print waveform in the productivity priority mode and the print waveform in the image quality priority mode are the same print waveform (print waveform A).

  Next, the relationship between the droplet length and the head electrode plate gap will be described. As shown in FIG. 7, the head electrode plate gap is set small when the droplet length is short, and the head electrode plate gap is set large when the droplet length is long.

  In the ejection detection device 200, as described above, when a positive charge is applied to the electrode plate 101, a negative charge is induced on the head 41 side, and the negative charge is accumulated on the nozzle surface 41a. The magnitude of the force that attracts negative charges depends on the head electrode plate gap, and is stronger as the gap is smaller and weaker as the gap is larger. Here, since the droplet discharged from the head 41 can be regarded as a part of the head 41 while being connected to the head 41, the distance (distance) between the tip of the droplet and the electrode plate 101 is charged. It can be regarded as a gap that determines the attractive force. Therefore, the head electrode plate gap is reduced for printing waveforms with a short droplet length of ejected droplets, and the head electrode plate gap is increased for printing waveforms with a short droplet length of ejected droplets. The plate gap can be made equal.

  Although FIG. 7 shows an example of setting for two paper types and two print modes, it is needless to say that the number of paper types and the number of print modes are not limited to these. In addition, for example, when there are three or more print modes for one paper type, it is a matter of course that both a print mode for selectively using a print waveform and a print mode for not properly using a print waveform may be included.

  Returning to the description of the flowchart of FIG. 6, in S102, it is determined whether the set paper type has a different print waveform depending on the print mode. If the paper type has no proper use (S102: No), for example, FIG. In the case of the plain paper in the example, the print waveform (print waveform A) used for the paper type (plain paper) is selected (S103).

  On the other hand, in the case of a paper type in which the print waveform is properly used (S102: Yes), for example, in the case of the coated paper in the example of FIG. 7, the print waveform used for the paper type (coated paper) is determined in advance. The printing waveform of the printing mode (default printing mode) is selected (S104). Here, the default print mode refers to a mode that is selected when the user transmits a job without specifying the print mode, and is set in advance for each paper type. For coated paper, the image quality priority mode is set as the default print mode, and the corresponding print waveform C is selected.

  This is because the print mode that is actually selected for printing is unknown until the job is received. For convenience, the print waveform of one of the print modes is set and the gap is adjusted accordingly. It is something to keep. Therefore, any print waveform corresponding to one print mode arbitrarily selected from the corresponding paper types may be selected.

  When the print waveform is selected in any one of steps S103 and S104, the gap control unit 516 controls the gap adjusting mechanism 520 so that the head electrode plate gap corresponding to the selected print waveform is obtained. The plate gap is adjusted (S105). After the head electrode plate gap is adjusted, the head electrode plate gap is changed to a standby state until the next head electrode plate gap change (S106).

  Next, the discharge detection control of the discharge detection device 200 will be described. FIG. 8 is a flowchart of the discharge detection control by the discharge detection device 200. The timing at which the discharge detection device 200 executes discharge detection is generally the following two cases. One is immediately before actual printing. In this case, a job is transmitted to the image forming apparatus, and ejection detection is executed immediately before the printing operation for the job is executed in the image forming apparatus. The other is immediately after maintenance operations such as preliminary ejection and cleaning operations. In this case, discharge detection is executed after completion of a predetermined maintenance operation. Of course, the discharge detection control may be executed at any timing other than the above two timings.

  In the discharge detection control, first, when there is a discharge detection request (S201), the gap control unit 516 determines whether or not it is before the start of the printing operation (S202). If it is not immediately before the printing operation (S202: No), that is, in the case of ejection detection after the maintenance operation, ejection detection is performed as it is in the state of the head electrode plate gap adjusted by the gap adjustment control in FIG. S207).

  On the other hand, if the print operation is not yet started (S202: Yes), the print mode information included in the job to be printed is referred to (S203), and the print waveform corresponding to the print mode is selected (S204). .

  Next, whether the head electrode plate gap corresponding to the print waveform selected in S204 matches the head electrode plate gap adjusted by the gap adjustment control in FIG. 6, that is, whether the head electrode plate gap needs to be readjusted. It is determined whether or not (S205). If readjustment is not necessary (S205: No), ejection detection is performed as it is in the state of the head electrode plate gap adjusted by the gap adjustment control of FIG. 6 (S207).

  On the other hand, when readjustment is necessary (S205: Yes), the gap control unit 516 controls the gap adjustment mechanism 520 to adjust the head electrode plate gap according to the print mode of the received job (S206). Discharge detection is executed (S207).

  For example, the coated paper is adjusted to the head electrode plate gap (small) corresponding to the print waveform C corresponding to the image quality priority mode which is the default print mode in the gap adjustment control of FIG. If the print mode of the job to be printed is the image quality priority mode, the gap readjustment is not necessary. However, if the print priority mode is the productivity priority mode, the head electrode plate gap corresponding to the print waveform B in the productivity priority mode ( Adjustment to large).

(Gap adjustment mechanism (1))
Next, the gap adjustment mechanism 520 will be described. FIG. 9 is an explanatory diagram of a first configuration example of the gap adjustment mechanism 520. The gap adjusting mechanism 520 includes a main scanning motor 5 and a main scanning encoder that control the main scanning position of the head 41, and an electrode plate 101 of the discharge detection unit 100 that is arranged in an inclined state in the main scanning direction. Composed.

  When the head 41 is located at the main scanning position shown in FIG. 9A, the gap between the head electrodes between the nozzle surface 41a of the head 41 and the receiving surface 102 of the electrode plate 101 is indicated by G1.

  On the other hand, when the main scanning position of the head 41 is the position shown in FIG. 9B, the head electrode gap G <b> 2 between the nozzle surface 41 a and the receiving surface 102 is caused by the inclination of the electrode plate 101. ) (G2> G1).

  When the main scanning position of the head 41 is the position shown in FIG. 9C, the head electrode gap G3 between the nozzle surface 41a and the receiving surface 102 is tilted by the electrode plate 101 as shown in FIG. ) (G3 <G1).

  That is, the gap between the head electrodes becomes G2> G1> G3, and the gap can be adjusted by changing the main scanning position of the head 41 with respect to the electrode plate 101. For example, in the example of FIG. 7, the gap “medium” when the gap G1 in FIG. 9A is the “medium” droplet length and the gap G2 of FIG. 9], the gap G3 in FIG. 9C can be set as the gap “small” when the droplet length is “short”.

  As described above, the electrode plate 101 is inclined and the stop position (that is, the ejection detection position) of the carriage 3 is set according to the droplet length of the print waveform to be used. It becomes possible to adjust the gap.

  In the first configuration example of the gap adjusting mechanism 520, when the carriage 3 includes five heads 41 (heads 41A to 41E) having two nozzle rows Na and Nb (2 nozzle rows × 5 heads), ejection detection is performed. Will be described with reference to FIG.

When the detection position is a position indicated by an arrow, discharge detection is performed while moving the carriage 3 as described below in order to perform discharge detection for all the nozzle rows of the head 41.
(1) The carriage 3 is moved so that the nozzle row Na of the head 41A becomes the detection position, and all the channels of the nozzle row Na of the head 41A are sequentially detected at this position.
(2) Next, the carriage 3 is moved so that the nozzle row Nb of the head 41A becomes the detection position, and all channels of the nozzle row Nb of the head 41A are sequentially detected at this position.
(3) Next, the carriage 3 is moved so that the nozzle row Na of the head 41B becomes the detection position, and all the channels of the nozzle row Na of the head 41B are sequentially detected at this position.
(4) Next, the carriage 3 is moved so that the nozzle row Nb of the head 41B becomes the detection position, and all the channels of the nozzle row Nb of the head 41B are sequentially detected at this position.
(5) The same applies to the heads 41C to 41E.

(Gap adjustment mechanism (2))
FIGS. 11 and 12 are explanatory diagrams illustrating a second configuration example of the gap adjusting mechanism 520. FIG. The gap adjusting mechanism 520 includes a main scanning motor 5 and a main scanning encoder that control the main scanning position of the head 41, and an electrode plate 101 of the discharge detection unit 100 having steps corresponding to the number of print waveforms in the main scanning direction. Is done.

  When the head 41 is located at the main scanning position shown in FIG. 11A, the gap between the head electrodes between the nozzle surface 41a of the head 41 and the receiving surface 102 of the electrode plate 101 is indicated by G1.

  On the other hand, when the main scanning position of the head 41 is the position shown in FIG. 11B, the head electrode gap G <b> 2 between the nozzle surface 41 a and the receiving surface 102 is caused by the step of the electrode plate 101. ) (G2> G1).

  When the main scanning position of the head 41 is the position shown in FIG. 11C, the head electrode gap G3 between the nozzle surface 41a and the receiving surface 102 is shown in FIG. ) (G3 <G1).

  That is, the gap between the head electrodes becomes G2> G1> G3, and the gap can be adjusted by changing the main scanning position of the head 41 with respect to the electrode plate 101.

  In the second configuration example of the gap adjusting mechanism 520, ejection detection when the carriage 3 includes five heads 41 (heads 41A to E) having two nozzle rows Na and Nb (2 nozzle rows × 5 heads). Will be described with reference to FIG.

  Here, a case where the electrode plate 101 is arranged in three steps and the second receiving surface 102 is a detection position will be described. As shown in FIG. 12, the discharge width in the main scanning direction of the entire head is larger than the detection position (discharge width of the entire head> detection position width of the electrode plate). In order to detect the ejection, the ejection is detected while moving the carriage 3.

That is, the processing flow is as follows.
(1) The carriage 3 is moved so that the head 41A is included in the detection position. At this position, all the channels of the nozzle row Na of the head 41A are detected in order.
(2) All the channels of the nozzle row Nb of the head 41A are detected in that order in that position.
(3) Next, the carriage 3 is moved so that the head 41B is included in the detection position, and all the channels of the nozzle row Na of the head 41B are sequentially detected at this position.
(4) All the channels of the nozzle row Nb of the head 41B are detected in order at that position.
(5) The same applies to the heads 41C to 41E.

  Here, the width of the detection position of the electrode plate 101, that is, the width of one step of the stepped electrode plate 101 is made larger than the interval between at least two nozzle rows of the head, whereby the number of movements of the carriage 3 is increased. Can be reduced. Further, the width of one step of the stepped electrode plate 101 is made larger than the discharge width of the entire head (the discharge width of the entire head <the width of the detection position of the electrode plate), so that the carriage 3 is not moved. Since it is possible to detect the discharge of the nozzles, it is possible to improve the efficiency of the discharge detection control.

  In this way, the electrode plate 101 is the stepped electrode plate 101 having the same number as the type of the printing waveform (drop length), and the stop position (that is, ejection) of the carriage 3 according to the droplet length of the printing waveform to be used. By setting the (detection position), the head electrode plate gap can be adjusted with a simple configuration. In addition, since the degree of freedom of the stop position of the carriage 3 is greater than in the example of FIG. 9, the influence of the stop position error of the carriage 3 can be eliminated.

  As described above, the apparatus for ejecting liquid according to the present embodiment performs ejection detection using the drive waveform actually used for printing and sets the optimum head electrode plate gap according to the type of drive waveform used. By adjusting, it becomes possible to detect the droplet discharge state with high accuracy by eliminating the mismatch between the discharge detection result and the discharge result at the time of actual printing.

  In the first and second configuration examples of the gap adjusting mechanism 520 described above, the electrode plate 101 is disposed so as to have an inclination or a step in the main scanning direction, and the head 41 changes the main scanning position. The example of ejecting the liquid has been described, but the movement direction of the head 41 in the gap adjustment control is not limited to this, and any movement is possible as long as it moves in a direction crossing the liquid ejection direction. At this time, the electrode plate 101 only needs to be inclined with respect to the nozzle surface according to the moving direction of the head 41 or arranged in a step shape when viewed from an angle parallel to the nozzle surface. The inclination direction or the direction having a step is not limited to the above example.

  In the first and second configuration examples of the gap adjusting mechanism 520 described above, the example in which the electrode plate 101 is fixed and the head electrode plate gap is adjusted by moving the head 41 has been described. In the gap adjustment control, the electrode plate 101 is moved in a direction crossing the liquid discharge direction without moving the head 41 in the gap adjustment control. The head electrode plate gap may be adjusted. Further, the head electrode plate gap may be adjusted while moving both the head 41 and the electrode plate 101 in a direction intersecting the liquid ejection direction.

  In the present application, the liquid to be ejected is not particularly limited as long as it has a viscosity and surface tension that can be ejected from the head, and the viscosity becomes 30 mPa · s or less at room temperature, normal pressure, or by heating and cooling. It is preferable. More specifically, solvents such as water and organic solvents, colorants such as dyes and pigments, functional materials such as polymerizable compounds, resins, and surfactants, and biocompatible materials such as DNA, amino acids, proteins, and calcium. , Edible materials such as natural pigments, solutions, suspensions, emulsions, and the like. These include, for example, inkjet inks, surface treatment liquids, components of electronic devices and light emitting devices, and formation of electronic circuit resist patterns. It can be used in applications such as liquids for use, three-dimensional modeling material liquids, and the like.

  As energy generation sources for discharging liquid, piezoelectric actuators (laminated piezoelectric elements and thin film piezoelectric elements), thermal actuators using electrothermal transducers such as heating resistors, electrostatic actuators consisting of a diaphragm and counter electrode are used. To be included.

  The “liquid ejection unit” is a unit in which functional parts and mechanisms are integrated with a liquid ejection head, and includes an assembly of parts related to liquid ejection. For example, the “liquid discharge unit” includes a combination of at least one of a head tank, a carriage, a supply mechanism, a maintenance / recovery mechanism, and a main scanning movement mechanism with a liquid discharge head.

  Here, the term “integrated” refers to, for example, a liquid discharge head, a functional component, and a mechanism that are fixed to each other by fastening, adhesion, engagement, etc., and one that is held movably with respect to the other. Including. Further, the liquid discharge head, the functional component, and the mechanism may be configured to be detachable from each other.

  For example, there is a liquid discharge unit in which a liquid discharge head and a head tank are integrated. Also, there are some in which the liquid discharge head and the head tank are integrated by being connected to each other by a tube or the like. Here, a unit including a filter may be added between the head tank and the liquid discharge head of these liquid discharge units.

  In addition, there is a liquid discharge unit in which a liquid discharge head and a carriage are integrated.

  In addition, there is a liquid discharge unit in which the liquid discharge head and the scanning movement mechanism are integrated by holding the liquid discharge head movably on a guide member that constitutes a part of the scanning movement mechanism. In some cases, a liquid discharge head, a carriage, and a main scanning movement mechanism are integrated.

  Also, there is a liquid discharge unit in which a cap member that is a part of the maintenance / recovery mechanism is fixed to a carriage to which the liquid discharge head is attached, and the liquid discharge head, the carriage, and the maintenance / recovery mechanism are integrated. .

  In addition, there is a liquid discharge unit in which a tube is connected to a liquid discharge head to which a head tank or a flow path component is attached, and the liquid discharge head and a supply mechanism are integrated. The liquid from the liquid storage source is supplied to the liquid discharge head via this tube.

  The main scanning movement mechanism includes a guide member alone. The supply mechanism includes a single tube and a single loading unit.

The “apparatus for ejecting liquid” includes an apparatus that includes a liquid ejection head or a liquid ejection unit and that ejects liquid by driving the liquid ejection head. The apparatus for ejecting a liquid includes not only an apparatus capable of ejecting a liquid to an object to which the liquid can adhere, but also an apparatus for ejecting the liquid into the air or liquid.

  This “apparatus for discharging liquid” may include means for feeding, transporting, and discharging a liquid to which liquid can adhere, as well as a pre-processing apparatus and a post-processing apparatus.

  For example, as a “liquid ejecting device”, an image forming device that forms an image on paper by ejecting ink, a powder is formed in layers to form a three-dimensional model (three-dimensional model) There is a three-dimensional modeling apparatus (three-dimensional modeling apparatus) that discharges a modeling liquid onto the powder layer.

  Further, the “apparatus for ejecting liquid” is not limited to an apparatus in which significant images such as characters and figures are visualized by the ejected liquid. For example, what forms a pattern etc. which does not have a meaning in itself, and what forms a three-dimensional image are also included.

  The above-mentioned “applicable liquid” means that the liquid can be attached at least temporarily and adheres and adheres, or adheres and penetrates. Specific examples include recording media such as paper, recording paper, recording paper, film, and cloth, electronic parts such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, and test cells. Yes, unless specifically limited, includes everything that the liquid adheres to.

  The material of the above-mentioned “material to which liquid can adhere” is not limited as long as liquid such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics can be adhered even temporarily.

  In addition, the “device for ejecting liquid” includes a device in which the liquid ejection head and the device to which the liquid can adhere move relatively, but is not limited thereto. Specific examples include a serial type apparatus that moves the liquid discharge head, a line type apparatus that does not move the liquid discharge head, and the like.

  In addition, as the “device for ejecting liquid”, other than the above, a treatment liquid coating apparatus that ejects a treatment liquid onto a sheet in order to apply the treatment liquid to the surface of the sheet for the purpose of modifying the surface of the sheet, There is an injection granulation apparatus that granulates raw material fine particles by spraying a composition liquid in which raw materials are dispersed in a solution through a nozzle.

  Note that the terms “image formation”, “recording”, “printing”, “printing”, “printing”, “modeling” and the like in the terms of the present application are all synonymous.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Main guide member 3 Carriage 5 Main scanning motor 6 Driving pulley 7 Driven pulley 8 Timing belt 12 Conveying belt 13 Conveying roller 14 Tension roller 16 Sub scanning motor 17 Timing belt 18 Timing pulley 20 Maintenance recovery mechanism 21 Suction cap 22 Moisturizing cap 23 Wiper Member 24 Empty discharge receptacle 27 Suction pump 29 Moving mechanism (elevating mechanism)
40 Liquid discharge unit 41a Nozzle surface 41n Nozzle 41 Liquid discharge head 42 Head tank 51 Cartridge holder 52 Liquid feed pump unit 50 Main tank 56 Supply tube 81 Empty discharge receiver 100 Discharge detection unit 102 Reception surface 101 Electrode plate 103 Holder member 104 Lead wire 123 Encoder scale 124 Encoder sensor 125 Code wheel 126 Encoder sensor 200 Discharge detection device 500 Control unit 500A Main control unit 501 CPU
502 ROM
503 RAM
504 Nonvolatile memory 505 ASIC
506 I / F
508 Print control unit 509 Head driver (driver IC)
510 Motor drive unit 511 Encoder analysis unit 512 Supply system drive unit 513 I / O unit 514 Operation panel 515 Discharge detection unit 516 Gap control unit 520 Gap adjustment mechanism 556 Maintenance recovery motor 570 Sensor group 572 Temperature sensor 600 Host 601 Printer driver 701 High Voltage power supply 702 Band pass filter (BPF)
703 Amplifier (AMP)
704 AD converter (ADC)
P paper

JP 2009-196291 A

Claims (7)

A liquid discharge head for discharging liquid;
An electrode member that receives the liquid discharged from the liquid discharge head and detects an electrical change caused by the liquid;
When one or both of the liquid discharge head and the electrode member move in a direction intersecting the liquid discharge direction, the distance between the liquid discharge head and the electrode member in the liquid discharge direction changes. A device for discharging a liquid characterized by the above. The liquid discharge head discharges the liquid by being given a drive waveform,
The apparatus for ejecting liquid according to claim 1, wherein the drive waveform used when detecting the electrical change is the same as the drive waveform used when forming an image on a recording medium. . There are multiple types of drive waveforms,
The apparatus for ejecting liquid according to claim 2, wherein the distance between the liquid ejection head and the electrode member is changed according to a type of the driving waveform.   The apparatus for discharging a liquid according to claim 1, wherein the electrode member is disposed with an inclination with respect to a nozzle surface of the liquid discharge head.   5. The apparatus for ejecting liquid according to claim 1, wherein the electrode member has a stepped shape when viewed from an angle parallel to a nozzle surface of the liquid ejection head. The liquid discharge head has at least two nozzle rows,
6. The apparatus for ejecting liquid according to claim 5, wherein a width of one step of the stepped electrode member is larger than an interval between the plurality of nozzle rows.   7. The apparatus for ejecting liquid according to claim 1, wherein the interval is adjusted when a paper type setting is changed.

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