JP2008114547A - Droplet discharge device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a droplet discharge device which can improve a precision of a striking position onto a recording medium. <P>SOLUTION: A printing timing mark 62 formed on an encoder film 64 attached to a rotating shaft of a driving roller 11 for conveying a sheet of recording paper is read by an encoder sensor 66. A conveyance speed of the recording paper is detected by a Doppler meter 95. On the basis of a detection timing of a reference position of the driving roller 11, a pulse width of a read signal is corrected to make a difference small between a movement speed detected by the Doppler meter 95 and a movement speed derived on the basis of the read signal by the encoder sensor 66. An ejection timing of liquid droplets by a droplet ejection head is controlled by using the corrected read signal. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a droplet discharge device.

  In a droplet discharge device such as an ink jet printer, a recording head is driven according to image data, and ink droplets are discharged from a nozzle of the recording head onto a recording medium to form an image.

  In an apparatus for printing by winding a sheet of paper around a drum, it is proposed that an encoder is provided in a drum drive motor, a print start timing is determined based on an output from the encoder, and used as a discharge timing signal (for example, , See Patent Document 1).

  In addition, in a system for transporting paper using a belt, it has been proposed to generate a print clock from the output of a rotary encoder on the rotating shaft of a drive roller (see, for example, Patent Document 2).

  In a recording head to which FWA (Full Width Array) technology in which a large number of nozzles are arranged side by side on a scanning line over the entire width of the recording medium is applied, for example, a code is placed on the rotating shaft of a drive roll for conveying the recording medium. There is a type in which a wheel is attached and a signal obtained by reading a mark on the code wheel with an optical sensor is used for controlling ink ejection timing.

The drive roll includes an eccentricity error in manufacturing. There are also mounting errors and mark printing errors on the code wheel on the code wheel side.
JP 2003-48352 A JP 2005-305919 A

  An object of the present invention is to provide a droplet discharge device capable of improving the landing position accuracy on a recording medium.

  According to a first aspect of the present invention, there is provided a droplet discharge head that discharges droplets onto a recording medium, a moving unit that moves the recording medium relative to the droplet discharge head, and a movement by the moving unit. An output means for generating a pulse signal having a pulse width including a periodic change, a reference position detection means for detecting a reference position of the periodic change, and detecting a moving speed of the recording medium by the moving means And a movement derived based on the movement speed detected by the movement speed detection means and the pulse signal output by the output means based on the detection timing of the reference position by the reference position detection means. Correction information generating means for generating the correction information for correcting the pulse width of the pulse signal so that the difference from the speed is small, and the correction information generating means before the correction information generating means Correction means for correcting the pulse width of the pulse signal output from the output means based on the storage means for storing correction information, the detection timing of the reference position by the reference position detection means and the correction information stored in the storage means And a head control unit that controls the droplet discharge timing by the droplet discharge head using the pulse signal corrected by the correction unit, and forms an image according to image information on a recording medium. A provided droplet discharge device.

  According to a second aspect of the present invention, the correction information generating unit generates the correction information based on data obtained by filtering the detection result of the moving speed detecting unit and removing noise of the moving speed change. The liquid droplet ejection apparatus described.

  According to a third aspect of the present invention, in the liquid droplet ejection apparatus according to the first or second aspect, the correction unit corrects each pulse width of the pulse signal output from the output unit.

  According to a fourth aspect of the present invention, in the liquid droplet ejection apparatus according to any one of the first to third aspects, the correction information generating means generates correction information for every predetermined number of consecutive pulse units.

  The invention according to claim 5 is the liquid droplet ejection apparatus according to any one of claims 1 to 4, further comprising an update unit that updates the correction information stored in the storage unit.

  According to a sixth aspect of the present invention, in the liquid droplet ejection apparatus according to any one of the first to fifth aspects, the recording medium is an intermediate transfer member.

  The invention of claim 7 includes a detector including the moving speed detecting means, an information processing device including the correction information generating means, the droplet discharge head, the moving means, the output means, the reference position detecting means, An image forming apparatus including the storage unit, the correction unit, and the head control unit, and the information processing apparatus is electrically connected to the detector and the image forming apparatus to detect the reference position. The information indicating the detection timing of the reference position by the means, the moving speed detected by the moving speed detecting means, and the pulse signal output by the output means can be acquired. Droplet discharge device.

  As described above, the present invention has an excellent effect that the landing position accuracy on the recording medium can be improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 schematically shows a configuration of an image forming apparatus 10 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 10 includes a paper feed tray 20 and a paper discharge tray 22 and a plurality of rollers 24.

  The recording paper P is accommodated in the paper feed tray 20, and at the time of image formation, the recording paper P in the paper feed tray 20 is taken out one by one by the rollers 24 and passes through the image forming apparatus 10 with a predetermined transport path F. Are discharged to the discharge tray 22.

  In the conveyance path F of the recording paper P, a conveyance belt 14 stretched between a driving roll 11 that rotates in the direction of arrow E and two driven rolls 12 that rotate in accordance with the rotation driving of the driving roll 11, An adsorber 16 is provided. The adsorber 16 presses the recording paper P conveyed on the conveying path F against the conveying belt 14 and applies electric charges to the recording paper P, and electrostatically adsorbs the recording paper P to the conveying belt 14.

  A registration roll 26 is disposed on the upstream side of the conveyance belt 14 in the conveyance path F of the recording paper P. The registration roll 26 performs paper skew correction to prevent the recording paper P conveyed along the conveyance path F from being attracted to the conveyance belt 14 in a distorted state in the conveyance direction.

  Further, in the conveyance path F of the recording paper P, yellow (Y), magenta (M), cyan (C), black (black) are provided at positions facing the recording surface of the recording paper P electrostatically attracted to the conveyance belt 14. A recording head array 18 including four recording heads 18Y, 18M, 18C, and 18K for ejecting ink of four colors K) is provided.

  The recording heads 18Y, 18M, 18C, and 18K for the respective colors have FWA (Full Width Array) in which head units each having a plurality of discharge nozzles are arranged over the entire width direction of the transport belt 14 and are configured by a large number of discharge nozzles. ) Type.

  In the following description, the members provided for each color are indicated by adding alphabets (Y / M / C / K) indicating the respective colors to the end of the reference numerals, but will be described without particularly distinguishing the colors. In this case, the explanation will be made by omitting the alphabet at the end of the code.

  As shown in the figure, the image forming apparatus 10 according to the present embodiment is configured to include a front / back reversing conveyance path R. When performing duplex printing, after forming an image on one side, the recording paper P is transported along the transport path R so that the back side of the surface on which the image is formed is placed on each of the recording heads 18Y, 18M, 18C, and 18K. Inversion can be performed so as to face each other.

  In addition, an ink tank 19 is provided between the conveyor belt 14 and the paper discharge tray 22 to store each color ink. The ink in the ink tank 19 is supplied to the recording heads 18Y, 18M, 18C, and 18K via an ink supply pipe (not shown).

  Here, the recording heads 18Y, 18M, 18C, and 18K are configured to be separated from the transport belt 14 by a drive mechanism (not shown).

  Furthermore, maintenance devices 28A and 28B are provided on the upstream side and the downstream side of the transport path F of the recording heads 18Y, 18M, 18C, and 18K, respectively. The maintenance device 28A includes a maintenance unit for black and cyan, and the maintenance device 28B includes a maintenance unit for magenta and yellow. Each of the maintenance devices 28A and 28B is configured to be movable in a direction approaching each other by a drive mechanism (not shown).

  As shown in FIG. 2, the recording heads 18Y, 18M, 18C, and 18K are moved away from the conveying belt 14 during maintenance. Further, at the time of maintenance, the maintenance devices 28A, 28B are moved to the space between the recording heads 18Y, 18M, 18C, 18K generated by the separation movement of the recording heads 18Y, 18M, 18C, 18K and the conveying belt 14.

  As a result, the maintenance units of the maintenance devices 28A and 28B are arranged to face the four recording heads 18Y, 18M, 18C, and 18K of the recording heads 18Y, 18M, 18C, and 18K, respectively, and the maintenance process by each maintenance unit is appropriately executed. The

  The maintenance process executed by the maintenance unit includes processes such as suction of ink liquid in the nozzle, wiping of ink droplets attached to the nozzle outlet, and supply of ink liquid into the nozzle.

  Here, as shown in FIG. 3, a disk-shaped encoder film 64 is attached to the rotation shaft of the drive roll 11 so as to rotate together with the drive roll 11. Print timing marks 62 are provided on the peripheral portion of the encoder film 64 in a radial pattern around the rotation axis of the drive roll 11.

  In addition, an encoder sensor 66 is provided at one position of the peripheral portion at a position facing the print timing mark 62. The encoder sensor 66 reads the print timing mark 62 that passes through the reading position. As the drive roll 11 rotates, the print timing mark 62 on the encoder film 64 sequentially passes through the reading position of the encoder sensor 66.

  The radial print timing marks 62 are provided at equal intervals. When the drive roll 11 rotates at a constant speed, the print timing marks 62 are read at a predetermined cycle. The detection cycle of the print timing mark 62 is the drive cycle. It changes according to the rotation speed of the roll 11.

  As shown in the figure, a reference position detection sensor 38 is provided in the vicinity of the drive roll 11. The reference position detection sensor 38 detects a reference position mark provided on the peripheral surface of the drive roll 11. The reference position mark is provided at one location of the drive roll 11, and the reference position mark is detected by the reference position detection sensor 38 every time the drive roll 11 rotates once. The reference position detection sensor 38 outputs a detection signal that becomes HIGH when a reference position mark is detected.

  Further, as shown in the figure, a paper leading edge detection sensor 36 for detecting the leading edge of the recording paper P adsorbed on the conveying belt 14 is arranged upstream of the recording head array 18 in the conveying direction of the recording paper P. It is installed. The sheet leading edge detection sensor 36 detects the presence or absence of a sheet at the detection position, and outputs a sheet leading edge detection signal that is HIGH when there is a sheet and LOW when there is no sheet. Therefore, the rising timing of the paper leading edge detection signal indicates the detection timing of the leading edge of the recording paper P.

  As shown in the figure, a Doppler measuring device 95 for detecting the conveyance speed of the conveyance belt 14 can be installed on the upstream side of the recording head array 18 in the conveyance direction of the recording paper P. . The Doppler measuring instrument 95 is installed at the position at the time of factory shipment, and the conveyance speed when the image forming apparatus 10 is actually driven is detected.

  FIG. 4 is a block diagram illustrating a configuration of a control system of the image forming apparatus 10 according to the present embodiment. As shown in FIG. 1, the image forming apparatus 10 includes a CPU 40, a ROM 42, a RAM 44, an interface (I / F), and the like that control the entire apparatus, and these are connected to a bus 48. Further, the CPU 40, the I / F 46, the input / output control unit 61, and the corrected print clock generation unit 70 are connected to the I / O line 49.

  The image forming apparatus 10 is connected to a host device such as a computer via the I / F 46 and performs printing based on image data transmitted from the host device.

  Further, an input / output control unit 61, a corrected print clock generation unit 70, and a recording head control unit 80 are further connected to the bus 48. The CPU 40 controls printing on the recording paper P by controlling the input / output control unit 61 and the recording head control unit 80.

  The input / output control unit 61 is connected to a maintenance drive circuit 50, a transport system drive circuit 54, and a belt drive circuit 58.

  A maintenance motor 52 that drives the maintenance unit 30 is connected to the maintenance drive circuit 50. The maintenance drive circuit 50 drives the maintenance motor 52 to clean the recording head 18 by the maintenance unit 30. That is, the input / output control unit 61 drives each drive circuit according to an instruction from the CPU 40, thereby conveying the recording paper P, cleaning the recording head 18, and the like.

  The conveyance system driving circuit 54 is connected to a conveyance system motor 56 that drives the rollers of the paths F and R and the like. Is transported.

  The belt driving circuit 58 is connected to a belt conveying motor 60 that drives the driving roller 11. When the belt driving circuit 58 drives the belt conveying motor 60, the conveying belt 14 rotates and the recording paper P is conveyed. .

  Further, the paper leading edge detection sensor 36, the reference position detection sensor 38, and the encoder sensor 66 are connected to the input / output control unit 61, and the detection results of each sensor are input, and the CPU 40 is based on the detection results of each sensor. The printing is controlled by.

  The corrected print clock generation unit 70 is connected to the recording head control unit 80. The corrected print clock generation unit 70 corrects the clock signal based on the read signal of the print timing mark 62 by the encoder sensor 66 based on preset correction information, and outputs the obtained corrected print clock to the recording head control unit 80. To do.

  The recording head control unit 80 is connected to the recording head 18 of each color via a head driving circuit 90. The recording head control unit 80 inputs an ink droplet ejection signal based on the image data to the head driving circuit 90 at a timing according to the corrected printing clock signal generated by the corrected printing clock generation unit 70, whereby the recording head 18. Ink droplet ejection control is executed.

  In other words, since ink droplets are ejected from the ejection nozzles of the recording head 18 in synchronization with the correction printing clock, one dot of ink droplet is ejected per printing clock.

  Further, the CPU 40 turns on an ejection permission (Enable) signal of each of the recording heads 18Y, 18M, 18C, and 18K that is input to the recording head control unit 80 at a timing based on the detection signal of the paper leading edge detection sensor 36 (see FIG. 5). ).

  FIG. 6 shows the configuration of the control system of the corrected print clock generation unit 70 according to the present embodiment. As shown in the figure, the correction print clock generation unit 70 includes a correction table storage unit 72, a correction processing unit 74, and a reference clock supply unit 76.

  The correction print clock generation unit 70 receives a read signal of the print timing mark 62 from the encoder sensor 66 and a reference position detection signal. The correction print clock generation unit 70 executes correction processing according to the correction information stored in the correction table storage unit 72 using the reference clock input from the reference clock supply unit 76 as an operation clock.

  The correction print clock generation unit 70 is supplied with a read signal of the print timing mark 62 from the encoder sensor 66 and a reference position detection signal. The correction print clock generation unit 70 corrects this read signal according to the correction information stored in the correction table storage unit 72.

  Specifically, the correction table storage unit 72 stores a correction table set in advance for every n steps, for example, with a plurality of consecutive clocks as one step.

  Here, as shown in FIG. 4, the image forming apparatus 10 is configured so that the external apparatus 100 can be connected thereto. In the present embodiment, the external apparatus 100 is connected to the image forming apparatus 10 at the time of factory shipment, and a correction table stored in the correction table storage unit 72 is created by the external apparatus 100.

  The external device 100 includes a microcomputer, and the Doppler measuring instrument 95 is connected to the external device 100.

  The Doppler measuring device 95 measures the reflected wave of the electromagnetic wave by measuring the reflected wave frequency by using the change of the reflected wave frequency by the Doppler effect when the object is moving in the traveling direction of the electromagnetic wave. Is calculated.

  FIG. 7 shows a functional block diagram related to the correction table creation processing of the external apparatus 100. As shown in the figure, the external device 100 includes a correction information deriving unit 110 and a correction table output unit 112.

  A surface velocity detection signal from the Doppler measuring instrument 95 is input to the external apparatus 100, and a reference position detection signal from the reference position detection sensor 38 and a reading signal from the encoder sensor 66 are input from the image forming apparatus 10.

  The correction information deriving unit 110 includes a data holding unit 102, a moving average deriving unit 104, a comparison calculation unit 106, and a data correction information calculation unit 108.

  As shown in FIG. 8, the data holding unit 102 holds data based on the read signal and the surface velocity detection signal during the period from the rising timing of the reference position detection signal to the next rising timing.

  At this time, with respect to the read signal, data indicating the read signal itself such as a pulse width and a duty ratio, data indicating the surface speed converted based on the read signal, and the like are held for each clock. As for the surface velocity detection signal, sampling of the surface velocity detection signal from the Doppler measuring device 95 is executed at intervals of 55 μsec, and sampling data is accumulated.

  Based on the data held in the data holding unit 102, the moving average deriving unit 104 filters out the surface velocity based on the read signal and the sampling data based on the surface velocity detection signal by applying noise to noise other than the eccentricity error and the mounting error. In order to remove them, a moving average of 400 sections is derived (see FIG. 9).

  The comparison operation unit 106 compares the 400-segment moving average value based on the read signal and the surface velocity detection signal corresponding to the same timing derived by the moving average deriving unit 104 to derive a difference (see FIG. 10). .

  The data correction information calculation unit 108 derives correction information q obtained by converting the derived difference into a pulse width correction amount for each predetermined number of pulse units.

  The correction information deriving unit 110 is connected to the correction table output unit 112, and the correction table output unit 112 accumulates the correction information derived by the correction information deriving unit 110 and outputs it as a correction table to the image forming apparatus 10. .

  The operation of the present embodiment will be described below.

  When a print request is sent together with transmission of print data from a host device such as a computer, the CPU 40 outputs the print data transmitted together with the print request to the recording head controller 80 and drives the conveyance system via the input / output controller 61. The conveyance system motor 56 is driven by controlling the circuit 54. As a result, the recording paper P is transported from the paper tray 20 along the transport path F to the transport belt 14.

  When the recording paper P is conveyed onto the conveying belt 14, the leading edge of the recording paper P is detected by the paper leading edge detection sensor 36 thereafter. When the detection result is input to the CPU 40 via the input / output control unit 61, the CPU 40 controls the head drive circuit 90 via the recording head control unit 80 to control printing by the recording head 18.

  That is, as shown in FIG. 5, the recording paper P detected by the paper leading edge detection sensor 36 is the recording position of each recording head 18Y, 18M, 18C, 18K (dropping position of ink ejected from the recording head 18). The injection permission signal is sequentially turned on at the timing of reaching. As a result, the color images are superimposed on the recording paper P to form a color image.

  Times B to E from the timing A when the leading edge of the recording paper P is detected to the timing when the ejection permission signals of the recording heads 18Y, 18M, 18C, and 18K are turned on are detected positions by the paper leading edge detection sensor 36. And the distance between the recording positions by the recording heads 18Y, 18M, 18C, and 18K, and the conveyance speed.

  The distance between the detection position by the paper leading edge detection sensor 36 and the recording position by each recording head 18 may be determined by a design value, or may be appropriately corrected and controlled in consideration of manufacturing variations at the time of factory shipment. Also good.

  Then, the recording paper P on which printing by the recording head 18 is performed is transported along the transport path F and discharged to the paper discharge tray 22.

  Next, the correction process of the print clock used as the control timing signal of the head drive circuit 90 in the recording head controller 80 will be described.

  FIG. 11 shows a read signal and a correction print clock based on the correction information q stored in the correction table storage unit 72. As shown in the figure, the correction processing unit 74 corrects the pulse width of the input read signal by the correction information q stored in the correction table storage unit 72. At this time, the same correction information q is used for the pulse width of the clock included in the same step.

  In the figure, the correction information q in step 0 is shown as q0, and the correction information q in step 1 is shown as q1. For example, if the correction information q0 of the first step 0 is assumed, the clock included in step 0 is output as a corrected print clock by adding the pulse width by q0.

  In the example shown in the figure, the correction processing unit 74 outputs the corrected print clock with a delay of two clocks from the read signal.

  In the present embodiment, a description has been given of a mode in which the delay period in the correction processing unit 74 is about two clocks of the print clock. However, the delay period may be appropriately set in consideration of the maximum speed fluctuation.

  In this embodiment, the correction value is calculated in units of a plurality of clocks, but may be corrected in units of one clock. The larger the speed difference, the smaller the clock unit, and if the speed difference is small, the number of clocks in the same step may be increased.

  In the present embodiment, the case where the present invention is applied to the image forming apparatus 10 that performs printing directly on the recording paper P has been described. However, an image is formed on the intermediate transfer member and is formed on the intermediate transfer member. The present invention can also be applied to an image forming apparatus 200 in which the transferred image is transferred to the recording paper P.

  FIG. 12 shows the configuration of the image forming apparatus 200. In the figure, the same components as those of the image forming apparatus 10 are denoted by the same reference numerals as those in FIG.

  As shown in the figure, the image forming apparatus 200 is configured to eject ink droplets onto the intermediate transfer belt 140 by the recording head 18. The intermediate transfer belt 140 is stretched around the drive roll 130 and the driven roll 132.

  The intermediate transfer belt 140 is flattened by a drive roll 130 and one driven roll 132 at a position facing the recording head 18.

  The intermediate transfer belt 140 has a transfer roll 134 and a peeling claw 136 disposed in this order along the rotational direction of the intermediate transfer belt 140 on the downstream side of the ink droplet ejection position by the recording head 18. Yes. The transfer roll 134 is pressed against the driven roll 27 via the intermediate transfer body belt 140, and the recording paper P is conveyed while being pressed against the intermediate transfer body belt 140, thereby recording an ink image from the intermediate transfer body belt 140. Transfer to paper P. Further, the peeling claw 136 peels the recording paper P from the intermediate transfer belt 140.

  As shown in the figure, a cleaning blade 138 is provided at a position facing the driven roll 132 on the downstream side in the belt rotation direction from the peeling claw 136 and on the upstream side in the belt rotation direction from the recording head 18. The cleaning blade 138 scrapes ink remaining on the intermediate transfer belt 140 without being transferred onto the recording paper P.

  Further, in the present embodiment, the form in which the print timing mark 62 attached to the encoder film 64 attached to the rotating shaft of the drive roll 11 is read and used as the print clock has been described, but the present invention is limited to this. It is not a thing.

  For example, as shown in FIG. 13, the present invention can also be applied to an apparatus in which a print timing mark 32 is attached to the conveyance belt 14. As shown in the figure, in the apparatus for ejecting ink droplets directly onto the recording paper P, the surface of the conveying belt 14 facing the recording head array 18 is hidden by the recording paper P even when the recording paper P is sucked and conveyed. A print timing mark 32 is attached to a portion that does not occur. The print timing marks 32 are provided at equal intervals in the transport direction over the entire circumference of the transport belt 14. The interval between the print timing marks 32 is set according to the resolution in the conveyance direction of the image forming apparatus 10.

  As shown in the figure, an encoder sensor 34 capable of detecting the print timing mark 32 is disposed upstream of the recording head array 18 in the conveyance direction of the recording paper P. As a result, the encoder sensor 34 sequentially detects the print timing marks 32 as the transport belt 14 is rotated by the drive roll 11.

  Further, a conveyance belt reference mark 31 is attached to one portion of the surface of the conveyance belt 14 that faces the recording head array 18. A conveyance belt reference mark detection sensor 33 capable of reading the conveyance belt reference mark 31 is disposed on the downstream side of the recording head array 18 in the conveyance direction of the recording paper P.

  The conveyance belt reference mark detection sensor 33 detects the conveyance belt reference mark 31 every time the conveyance belt 14 makes one rotation as the conveyance belt 14 is rotated by the drive roll 11.

  In the figure, an apparatus for ejecting ink droplets directly onto the recording paper P is shown. However, the apparatus can be applied to the image forming apparatus 200 as long as the conveying belt 14 is read as the intermediate transfer body 140.

  Further, in the present embodiment, the correction table is described as being created at the time of factory shipment, but the present invention is not limited to this. When exchanging the conveyance belt, the correction table may be created again by connecting the external device 100 of this embodiment and the Doppler measuring instrument 95. Further, the Doppler measuring instrument 95 may be mounted on the image forming apparatus, and the correction table may be updated periodically. The update timing of the correction table may be when maintenance is completed, every predetermined number of sheets (for example, 10,000 sheets) is recorded, at initialization.

  Note that the configuration of the image forming apparatus 10 according to the above-described embodiment (see FIGS. 1 to 4, 6, and 7) is an example, and can be changed as appropriate without departing from the spirit of the present invention.

  Further, the processing flow according to the above-described embodiment (see FIGS. 8 and 11) is an example, and it is needless to say that it can be appropriately changed without departing from the gist of the present invention.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment. It is a figure which shows the positional relationship of the recording head at the time of a maintenance, a maintenance apparatus, and a conveyance belt. FIG. 2 is a schematic diagram illustrating a configuration around a recording head according to an embodiment. It is a control block diagram concerning an embodiment. 6 is a timing chart showing the relationship between recording paper conveyance timing, printing clock, and printing permission timing for each recording head. It is a block diagram regarding the correction process of the printing clock which concerns on embodiment. It is a functional block diagram regarding creation of a correction table. It is a timing chart which shows the data used in order to produce a correction table. It is a graph showing the detection result of a Doppler measuring device and an encoder sensor as 400 moving averages. It is a graph showing the difference of the detection result of a Doppler measuring device, and the detection result of an encoder sensor. 6 is a timing chart showing a reference print signal output from a reference position detection signal, a read signal, and a correction print clock generator. It is the schematic which shows the structure of the image forming apparatus which concerns on another form. It is the schematic which shows the structure of the recording head periphery which concerns on another form.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Drive roll 12 Driven roll 14 Conveyance belt 18 Recording head 20 Paper tray 22 Paper discharge tray 24 Roll 36 Paper front-end detection sensor 38 Reference position detection sensor 40 CPU
42 ROM
44 RAM
62 Print timing mark 64 Encoder film 66 Encoder sensor

Claims (7)

A droplet discharge head for discharging droplets on a recording medium;
Moving means for moving the recording medium relative to the droplet discharge head;
Output means for outputting a pulse signal having a pulse width including a periodic change, generated with movement by the moving means;
A reference position detecting means for detecting a reference position of the periodic change;
A moving speed detecting means for detecting a moving speed of the recording medium by the moving means;
Based on the detection timing of the reference position by the reference position detecting means, the difference between the moving speed detected by the moving speed detecting means and the moving speed derived based on the pulse signal output by the output means becomes small. Correction information generating means for generating the correction information for correcting the pulse width of the pulse signal,
Storage means for storing the correction information generated by the correction information generation means;
Correction means for correcting the pulse width of the pulse signal output from the output means based on the detection timing of the reference position by the reference position detection means and the correction information stored in the storage means;
Head control means for controlling the ejection timing of the droplets by the droplet ejection head using the pulse signal corrected by the correction means to form an image according to image information on a recording medium;
A droplet discharge device comprising:   The droplet discharge apparatus according to claim 1, wherein the correction information generation unit generates the correction information based on data obtained by filtering a detection result of the movement speed detection unit and removing noise of a change in movement speed.   The droplet discharge apparatus according to claim 1, wherein the correction unit corrects each pulse width of the pulse signal output from the output unit.   4. The droplet discharge device according to claim 1, wherein the correction information generation unit generates correction information for every predetermined number of consecutive pulse units. 5.   The liquid droplet ejection apparatus according to claim 1, further comprising an update unit that updates correction information stored in the storage unit.   The liquid droplet ejection apparatus according to claim 1, wherein the recording medium is an intermediate transfer member. A detector including the moving speed detecting means;
An information processing apparatus including the correction information generating means;
An image forming apparatus including the droplet discharge head, the moving unit, the output unit, the reference position detection unit, the storage unit, the correction unit, and the head control unit;
With
The information processing apparatus is electrically connected to the detector and the image forming apparatus, so that a reference position detection timing by the reference position detection means, a movement speed detected by the movement speed detection means, and the output The liquid droplet ejection apparatus according to claim 1, wherein information indicating a pulse signal output by the means can be acquired.

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