JP2012137632A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress color shift caused by conveyance shift of a transfer material in an image forming apparatus which prints an image on the transfer material using a plurality of image forming parts.SOLUTION: An image forming apparatus of the present invention is characterized in comprising: a transfer material position adjustment part for adjusting a position in a direction orthogonal to or nearly orthogonal to a conveyance direction of a transfer material conveyed by a conveyance part; a timing determination part for determining a timing of detecting a position of an end surface of the transfer material by a second sensor according to a timing of detecting a position of the end surface of the transfer material by a first sensor; and a control part for adjusting a position of the transfer material at the transfer material position adjustment part according to information of the position of the end surface of the transfer material detected by the first sensor and information of the position of the end surface of the transfer material detected by the second sensor.

Description

  The present invention relates to an image forming apparatus and an image forming method for forming an image on a transfer material using a liquid developing method or an ink jet method, and in particular, an image using a plurality of color developers on a transferred transfer material. The present invention relates to an image forming apparatus and an image forming method.

  2. Description of the Related Art An image forming apparatus is known that transports a transfer material such as paper or cloth and forms an image on a transfer portion using a plurality of color image forming portions arranged in parallel in the transport direction. In such an image forming apparatus, since a shift in the printing position in the transfer material conveyance direction appears as a color shift, the printing timing between the image forming units is controlled. In addition, in the width direction of the transfer material, that is, the direction orthogonal to the transfer material conveyance direction, if the transfer material meanders and is conveyed, color misregistration occurs.

  Patent Document 1 describes that meandering correction is performed in a double-sided printing apparatus that prints both sides of a web (transfer material) such as paper or cloth. Specifically, a first edge guide (meandering correction mechanism) and a first edge sensor are arranged upstream of the first surface printing unit that prints one side of the web, and the web edge position detected by the first edge sensor is detected. According to the amount of deviation from the target position, the first edge guide is moved to correct the meandering of the web. A second edge guide and a second edge sensor are also arranged downstream of the first surface printing unit, and the second edge guide is moved according to the amount of deviation detected by the second edge sensor, similarly to the upstream side of the web. I am letting.

JP 2006-142632 A

  However, in the apparatus disclosed in Patent Document 1, when the edge position fluctuates due to uneven molding of the edge of the web (transfer material), fluff, etc., the web is placed between the ink jet bars arranged in parallel in the first surface printing section. The ink was moved more than necessary in the width direction, and printing misalignment (color misregistration) occurred between the ink jet bars.

  Further, in this apparatus, since the first edge guide is moved by the amount of deviation detected by the first edge sensor and the second edge guide is moved by the amount of deviation detected by the second edge sensor, the ink jet bar disposed on the upstream side. When the image formed in (1) reached the inkjet bar positioned on the downstream side, the relative position between the inkjet bar and the formed image became inappropriate, and color misregistration occurred similarly.

In order to solve the above problems, an image forming apparatus according to the present invention includes a conveyance unit that conveys a transfer material, a first image formation unit that forms an image on a transfer material conveyed by the conveyance unit, and the first A second image forming unit that forms an image on the transfer material on which the image is formed by the image forming unit, and a first position that detects the position of the end surface in the transport direction of the transfer material transported by the transport unit. A sensor, a second sensor for detecting a position of an end face in the transport direction of the transfer material, which is transported by the transport unit and detected by the first sensor, and transport of the transfer material transported by the transport unit A transfer material position adjusting unit that adjusts a position in a direction orthogonal or substantially orthogonal to the direction; and a timing at which the position of the end face of the transfer material is detected by the first sensor, and the transfer material is detected by the second sensor. The timing to detect the position of the end face of The transfer material based on the timing determination unit, information on the position of the end face of the transfer material detected by the first sensor, and information on the position of the end face of the transfer material detected by the second sensor A control unit for adjusting the position of the transfer material by a position adjustment unit;
It is characterized by having.

  Furthermore, in the image forming apparatus according to the present invention, the transport unit transports the transfer material to a position where an image is formed by the image forming unit.

  Furthermore, in the image forming apparatus according to the present invention, the transport unit includes two rollers that stretch the transfer material at a position where an image is formed by the first image forming unit and the second image forming unit. The first sensor and the second sensor are arranged between the two rollers that stretch the transfer material.

  Furthermore, in the image forming apparatus according to the present invention, the timing at which the end position of the transfer material is detected by the second sensor is a predetermined time after the position of the end surface of the transfer material is detected by the first sensor. The timing has passed.

  Further, in the image forming apparatus according to the present invention, the predetermined time used for determining the timing for detecting the position of the end face of the transfer material by the second sensor is changed based on the transfer speed of the transfer material. It is said.

  Furthermore, the image forming apparatus according to the present invention includes a third sensor that detects a transport distance of the transfer material, and the timing at which the second sensor detects the position of the end surface of the transfer material is the first sensor. After the position of the end surface of the transfer material is detected by the sensor, the timing at which the third sensor detects that the transfer material has been transported a predetermined transport distance is set.

  Furthermore, the image forming apparatus according to the present invention includes a frame for fixing the image forming unit, and the first sensor and the second sensor are disposed on the frame.

  In the image forming method according to the present invention, the position of the end surface of the transfer material conveyed in the conveyance unit is detected by the first sensor, and the position of the end surface of the transfer material is detected by the first sensor. And determining a timing for detecting the position of the end face of the transfer material by the second sensor, and forming an image by the first image forming unit on the transfer material conveyed by the conveyance unit, The position of the end surface of the transfer material conveyed by the conveyance unit is detected by the second sensor at a determined timing, and the position of the end surface of the transfer material detected by the first sensor, and the first And adjusting the position of the transfer material in a direction orthogonal or substantially orthogonal to the transport direction of the transfer material transported by the transport unit based on the position of the end surface of the transfer material detected by the sensor of 2; Transport by the transport unit It is an possible and forming an image by the second image forming unit to the transfer material to be.

1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a configuration of an image forming unit according to an embodiment of the present invention. The figure which shows the structure of the 1st (2nd) sensor which concerns on embodiment of this invention. The figure which shows the structure and operation | movement of a meandering correction | amendment part which concern on embodiment of this invention. The figure which shows the mode of image formation part and 1st, 2nd sensor arrangement | positioning with respect to a transfer material. FIG. 6 is a diagram for explaining transfer material meandering correction according to an embodiment of the present invention. The block diagram which shows the control structure of meandering correction which concerns on embodiment of this invention. The flowchart which shows the process of the meander correction | amendment which concerns on embodiment of this invention. The flowchart which shows the detection timing determination process which concerns on embodiment of this invention. FIG. 6 is a diagram showing a configuration of an image forming apparatus according to another embodiment of the present invention. The block diagram which shows the control structure of meandering correction which concerns on other embodiment of this invention. The flowchart which shows the detection timing determination process which concerns on other embodiment of this invention. The figure which shows the mode that the image formation part which concerns on embodiment of this invention, and a 1st, 2nd sensor are fixed.

  The image forming apparatus of the present embodiment develops a latent image using a high-viscosity liquid developer in which a toner composed of a solid component is dispersed in a liquid solvent (carrier liquid), and visualizes the electrostatic latent image. Forming device. The liquid developer used in this wet image forming apparatus is a solid developer (toner particle) suspended in a highly viscous carrier liquid having electrical insulation properties such as silicone oil, mineral oil, and edible oil. The toner particles are extremely fine with a particle diameter of around 1 μm. By using such fine toner particles, the wet image forming apparatus can achieve higher image quality than a dry image forming apparatus using powder toner particles having a particle diameter of about 7 μm.

  The present invention is not limited to such a wet image forming apparatus, but can be used for an image forming apparatus using an ink jet method, or an image forming apparatus of another method such as a dry image forming apparatus. It is.

  FIG. 1 is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus is viewed from the side, and when a coordinate axis is set as shown in the figure, the transfer material S has a width in the Z direction. The image forming apparatus mainly includes color image forming units 1Y, 1M, 1C, and 1K that transfer (print) an image to a transfer material S, a transport unit that transports the transfer material S, and a position of an end surface of the transfer material. The first sensor 6A and the second sensor 6B are arranged on the same end surface side of the transfer material S in order to detect this. As the transfer material S, a plastic film or the like is used in addition to paper and cloth.

  The transport unit of the present embodiment is wound around the unwinding shaft portion 41 disposed on the downstream side by rotationally driving the winding shaft portion 47 disposed on the upstream side of the image forming units 1Y to 1K. The transfer material S (unwinding roll Sa) is taken up and conveyed. The printed transfer material S is taken up by the take-up shaft 47 and becomes a take-up roll Sb. Further, in order to form a transport path for the transfer material S, the first roller 42, the meandering correction unit 43, the second roller 44, the third roller 45, and the fourth roller 46 are arranged from the unwinding side to the winding side. It is installed.

  The transfer material S transported by the transport unit, specifically, transport by rotationally driving the take-up shaft 47 or the like may be either a constant transport type or an intermittent transport type. . In the case of intermittent conveyance, an image having a width in the conveyance direction is formed by the image forming units 1Y to 1K when conveyance is stopped, and the transfer material S is conveyed after the image is formed. In this embodiment, the transfer material S that is continuously conveyed between the unwinding roll Sa and the take-up roll Sb is used. However, the transfer material S is not limited to such a form and is folded. A transfer material S that is fed out and continuously conveyed may be used.

  The meandering correction unit 43 ("transfer material position adjusting unit" of the present invention) shifts in the width direction (Z direction) of the transfer material S, specifically, in the direction orthogonal or substantially orthogonal to the transfer direction of the transfer material S. This is a configuration to be corrected, and the pair of front roller 43a and rear roller 43b is rotated in the XZ plane so that the transfer material S to be conveyed is moved in the width direction and transferred by the image forming units 1Y to 1K. The image printed on the material S is corrected to an appropriate position. The detailed configuration and control will be described in detail later.

The second roller 44 and the third roller 45 are rollers that form a transfer surface for transferring an image in the image forming units 1Y to 1K, and transfer is performed by stretching the transfer material S between these two rollers. A surface is formed.

  The four image forming units 1Y to 1K transfer images using respective color liquid developers of Y (yellow), M (magenta), C (cyan), and K (black). Based on image information input to a control unit (not shown), the image forming units 1Y to 1K are controlled to transfer an image onto the transfer material S. The image forming units 1Y to 1K are arranged in parallel with the transfer direction of the transfer material S as shown in the figure, and images are transferred in the order of the image forming units 1Y, 1M, 1C, and 1K. A final image is formed and wound on the winding shaft 47.

  The first sensor 6 </ b> A and the second sensor 6 </ b> B are sensors that detect the position of the end surface of the transfer material S, and are disposed on the same end surface side of the transfer material S. Various types of sensors such as an optical system, an ultrasonic system, and a mechanical system can be used. Based on the information on the position of the end face of the transfer material S detected by the two sensors 6A and 6B, the meandering correction for the meandering correction unit 43 is executed, details of which will be described later.

  FIG. 2 is a diagram showing a main configuration of the image forming unit 1Y in yellow (Y) color in the image forming apparatus according to the embodiment of the present invention. This figure is a view seen from the same direction as FIG. Since the configurations of the other image forming units 1M, 1C, and 1K are the same, the description will be made based on the yellow (Y) image forming unit 1Y.

  The image forming unit 1Y of this embodiment is a system that uses a liquid developer to transfer an image to a transfer material, and includes a developing unit and a transfer unit.

  The developing unit is a device that develops a latent image formed on the photoreceptor 10Y with a liquid developer, and includes a developing roller 20Y, an intermediate roller 32Y, an anilox roller 33Y, and a liquid developer that stores the liquid developer. The toner charger 22Y for charging the toner on the agent container 31Y and the developing roller 20Y is a main component.

  A cleaning blade 21Y, an intermediate roller 32Y, and a toner charger 22Y are arranged on the outer periphery of the developing roller 20Y. The surface of the intermediate roller 32Y is in contact with the developing roller 20Y and the anilox roller 33Y, and an intermediate roller cleaning blade 34Y is disposed on the outer periphery thereof.

  The anilox roller 33Y is in contact with a regulating member 35Y that adjusts the amount of liquid developer pumped from the developer reservoir 311Y. In the three-roller system using the intermediate roller 32Y as in the developing device of the present embodiment, the amount of liquid developer can be adjusted by the intermediate roller 32Y coming into contact with the anilox roller 33Y. It is also possible to adopt a configuration in which the restricting member 35Y is not provided.

  The developer storage unit 311Y is supplied with a liquid developer whose toner concentration is adjusted by a developer supply unit (not shown). Further, by providing a path for returning the developer storage unit 311Y to the developer supply unit, the liquid developer is circulated between the developer storage unit 311Y and the developer supply unit, and the liquid developer used for printing can be circulated. The toner density can be controlled.

The liquid developer contained in the developer container 31Y is a low-concentration (about 1 to 2 wt%) and low-viscosity volatile at room temperature using a conventionally used Isopar (trademark: exon) as a carrier. Is a non-volatile liquid developer having a high concentration and high viscosity and having non-volatility at room temperature. That is, in the liquid developer in the present invention, a solid having an average particle diameter of 1 μm in which a colorant such as a pigment is dispersed in a thermoplastic resin is introduced into a liquid solvent such as an organic solvent, silicone oil, mineral oil, or edible oil. Viscoelasticity at a shear rate of 1000 (1 / s) at 25 ° C. using a high viscosity (HAAKE RheoStress RS600) added with a dispersant and having a toner solid content concentration of about 25%. Liquid developer.

  The anilox roller 33Y functions as an application roller that supplies and applies a liquid developer to the intermediate roller 32Y. This anilox roller 33Y is a cylindrical member, and is a roller having a concave and convex surface formed by grooves engraved finely and uniformly on the surface so as to easily carry the developer on the surface. The anilox roller 33Y supplies the liquid developer from the developer reservoir 311Y to the developing roller 20Y. During operation of the apparatus, as shown in the figure, the anilox roller 33Y rotates counterclockwise to apply the liquid developer to the intermediate roller 32Y.

  The regulating member 35Y is a metal blade having a thickness of about 200 μm, is placed on the surface of the anilox roller 33Y, regulates the film thickness and amount of the liquid developer carried and carried by the anilox roller 33Y, and develops The amount of the liquid developer supplied to the roller 20Y is adjusted.

  The intermediate roller 32Y is a cylindrical member, and as shown in the drawing with the rotation axis as the center, the intermediate roller 32Y rotates clockwise like the developing roller 20Y and counter-contacts the developing roller 20Y. Similar to the developing roller 20Y, the intermediate roller 32Y is configured by providing an elastic layer on the outer periphery of a metal inner core.

  An intermediate roller cleaning blade 34Y is disposed in contact downstream of the contact position between the intermediate roller 32Y and the developing roller 20Y, and the liquid developer that has not been supplied to the developing roller 20Y is scraped off and collected.

  The developing roller 20Y is a cylindrical member, and rotates clockwise around the rotation axis as shown in the figure. The developing roller 20Y is provided with an elastic layer such as polyurethane rubber, silicon rubber, NBR, or PFA tube on the outer periphery of an inner core made of metal such as iron. A developing bias is applied to the developing roller 20Y, and the developing bias is applied to the metal inner core.

  The developing roller cleaning blade 21Y is disposed downstream of the developing nip portion where the developing roller 20Y contacts the photoreceptor 10Y in the rotation direction of the developing roller 20Y, and scrapes and collects the liquid developer remaining on the developing roller 20Y. .

  The toner charger 22Y is an electric field applying unit that applies an electric field to the liquid developer applied to the developing roller 20Y and presses (compresses) the toner particles in the liquid developer toward the developing roller. The toner charger 22Y of this embodiment uses a corona charger that applies an electric field by corona discharge, such as corotron and scorotron. In addition, as means for applying an electric field to the liquid developer, a bias blade or a bias roller may be used.

  The transfer unit includes a photoconductor 10Y and a corona charger 11Y, an exposure unit 12Y, a photoconductor cleaning blade 18Y, a transfer backup roller 19Y, and the like that are sequentially arranged along the rotation direction of the outer periphery of the photoconductor 10Y. . This transfer portion contacts the developing roller 20Y of the developing portion on the outer periphery of the photoreceptor 10Y and downstream of the exposure unit 12Y.

  The photoconductor 10Y is a photoconductor drum made of a cylindrical member having a photosensitive layer such as an amorphous silicon photoconductor formed on the outer peripheral surface, and rotates in the counterclockwise direction.

  The corona charger 11Y is disposed upstream of the nip portion between the photoconductor 10Y and the developing roller 20Y in the rotation direction of the photoconductor 10Y, and a voltage is applied from a power supply device (not shown) to corona-charge the photoconductor 10Y. The exposure unit 12Y irradiates light onto the photoconductor 10Y charged by the corona charger 11Y downstream of the corona charger 11Y in the rotation direction of the photoconductor 10Y, thereby forming a latent image on the photoconductor 10Y.

  The latent image formed on the photoreceptor 10Y is developed with a liquid developer applied to the developing roller 20Y to become a developer image. The developer image formed on the photoreceptor 10Y is transferred to the transfer material S by passing through a transfer nip formed by the photoreceptor 10Y and the transfer backup roller 19Y, and forms an image on the transfer material S. .

  When the rotation of the photoconductor 10Y further proceeds, the developer image, which is the transfer residue on the photoconductor 10Y, is scraped off and collected by the photoconductor cleaning blade 18Y disposed on the downstream side of the transfer nip.

  The image forming unit 1Y for yellow (Y) has been described above as an example, but the image forming units 1M, 1C, and 1K for other colors have the same configuration. These color image forming portions 1Y to 1K are arranged in parallel in the transfer direction of the transfer material S, and a multicolor image is formed on the transfer material S by sequentially superimposing developer images. In the method using a liquid developer, a fixing unit for fixing the image formed on the transfer material S may be provided between the image forming units 1Y to 1K and the take-up roll Sb. In the fixing unit, the developer image formed on the transfer material S is fixed by applying heat or pressure.

  FIG. 3 is a diagram showing a configuration of the first (second) sensor according to the embodiment of the present invention. The first sensor 6 </ b> A and the second sensor 6 </ b> B are sensors for detecting the position E of the end surface of the transfer material S being conveyed, and an optical method is employed in this embodiment. Both of the sensors 6A and 6B have the same configuration, and include a support member 61, a light emitting unit 62, and a light receiving unit 63. The light emitting unit 62 and the light receiving unit 63 are disposed on the support member 61 so as to face each other. The position E of the end surface of the transfer material S passes between the light emitting unit 62 and the light receiving unit 63 facing each other. A part of the light emitted from the light emitting unit 62 is shielded by the transfer material S passing between them, and it is possible to detect where the position E of the transfer material end surface is located by the amount of light received by the light receiving unit 63. Become. Instead of the sensor using the light emitting unit 62 and the light receiving unit 63 that detect using light, an oscillation unit that uses sound waves (ultrasonic waves) and a sensor that uses a receiving unit may be used. Alternatively, a mechanical sensor using a contactor that touches lightly the position E may be used.

  In the present embodiment, the meandering correction unit 43 is controlled based on the information on the position of the end face output from the first sensor 6A and the second sensor 6B that detect the position E of the end face E of the transfer material by such a mechanism. In addition, the positional deviation in the width direction of the transfer material is suppressed.

  FIG. 4 is a diagram showing the configuration and operation of the meandering correction unit according to the embodiment of the present invention. This figure is a view of the meandering correction unit 43 viewed from the lower surface side of the image forming apparatus shown in FIG. 1, that is, from the Y-axis direction. As described with reference to FIG. 1, the meandering correction unit 43 includes a front roller 43a and a rear roller 43b. These rollers 43a and 43b are rotatably supported and transport the wound transfer material S in the transport direction shown in the figure (downward in the figure).

In addition, the meandering correction unit 43 includes rotation shafts 431a and 431b, a frame 433, and rotation shaft support portions 432a and 432b. The front roller 43a includes a rotation shaft 431a at both ends, and is fixed on the frame 433 so as to be rotatable by a rotation shaft support portion 432a. Similarly, in the rear roller 43b, the rotation shafts 431b provided at both ends are fixed to the frame 433 so as to be rotatable by the rotation shaft support portion 432b. Similarly, the other ends of the rollers 43a and 43b are affirmed to be rotatable on the frame 433. On the other hand, the frame 433 is provided with a rotation fulcrum 434 and is configured to be rotatable about this. Thus, the front roller 43a and the rear roller 43b disposed on the same frame 433 rotate in the same direction as the frame 433 rotates. The meandering correction of the transfer material S is executed by controlling the rotation of the frame 433 by a meandering correction actuator (not shown).

  FIG. 4B is a diagram showing a state at the time of meandering correction, and shows a state when the frame 433 rotates clockwise. The end face of the transfer material in FIG. 4A is supplementarily indicated by a broken line A, but it can be seen that the transfer material moves to the left as indicated by the solid line B as the frame 433 rotates. In the present embodiment, the transfer position of the transfer material S is adjusted to an appropriate position by rotating the frame 433 based on the information on the position of the end face output from the first sensor 6A, the second sensor 6B, and the two sensors. I am going to do that.

  Now, the arrangement of the transfer material S, the first sensor A, the second sensor 6B, and the image forming units 1Y to 1K will be described with reference to FIGS. FIG. 5 is a diagram illustrating a state in which the image forming unit and the first and second sensors are arranged on the transfer material. Although the state of the transfer material S being conveyed is shown in the drawing, the state of the end surface E of the transfer material S is exaggerated for easy understanding. The end surface E of the transfer material S has a wavy shape as shown in the figure, due to misalignment or fluffing of the end surface E of the transfer material, in addition to a positional shift caused by meandering of the transfer material S itself. That is, when the position of the end surface E of the transfer material is detected by a single sensor, it is not possible to cope with fluctuations due to molding unevenness or scratches on the end surface E of the transfer material.

  For this reason, in the present embodiment, two sensors 6A and 6B are used. In particular, in the present embodiment, the image forming units 1Y to 1K are disposed in the vicinity of the image forming units 1Y to 1K in order to suppress the shift of the image transfer position. Preferably, in order to form an image on the transfer material S by the image forming units 1Y to 1K using the sensors 6A and 6B, the second roller 44 and the third roller 45 that stretch the transfer material S to form a transfer surface are preferably used. Arranged between. According to such an arrangement configuration, it is possible to detect the position of the end face at the stretch position of the transfer material S where color misregistration actually occurs and adjust the position with respect to the stretch position. More preferably, the first sensor 6A is disposed in the vicinity of the upstream side of the image forming unit 1Y positioned on the most upstream side, and the second sensor 6B is disposed in the vicinity of the upstream side of the image forming unit 1M positioned second. With such an arrangement, the positional deviation of the transfer material S downstream of the sensors 6A and 6B is suppressed, the transferred image between the image forming units 1Y to 1K is corrected to an appropriate position, and between the transferred images. It is possible to suppress the shift (color shift).

  FIG. 6 is a view for explaining meandering correction of the transfer material S according to the embodiment of the present invention. The positions of images transferred to the same position on the transfer material S by the image forming units 1Y and 1M are indicated by black circles. When the meandering correction is not performed, the transfer material S is conveyed in a linear direction connecting the black circles shown in the image forming unit 1Y and the image forming unit 1M, and is indicated by a broken-line circle in the image forming units 1C and 1K located downstream. The transfer between the transferred images becomes large.

  On the other hand, in this embodiment, after the transfer material position Ea of the transfer material S is detected by the first sensor 6A, the same or substantially the same transfer material position Ea is detected by the second sensor 6B, and the shift amount d1 is set. Measuring. By driving the meandering correction unit 43 in accordance with the deviation amount d1, it is possible to correct the positional deviation in the width direction of the conveying material S. Note that, if the meandering correction by the meandering correction unit 43 is performed in a short time, it becomes a load on the transfer material S and image shift due to the correction becomes conspicuous. In the example shown in the figure, the meandering correction is performed so that the transfer material S is positioned at an appropriate position when the transfer material S is conveyed to the image forming unit 1K.

  The control of the meandering correction unit 43 based on the position information of the end face of the transfer material detected by the first sensor 6A and the second sensor 6B will be described with reference to FIGS. FIG. 7 is a block diagram showing a control configuration of meander correction according to the embodiment of the present invention, FIG. 8 is a flowchart showing processing of meander correction according to the embodiment of the present invention, and FIG. It is a flowchart which shows the detection timing determination process which concerns on embodiment of invention.

  As described with reference to FIG. 4, the meandering correction of the transfer material S is performed by rotating the frame 433 around the rotation fulcrum 434. This rotation is performed by driving the meandering correction actuator 436. As shown in FIG. 7, the control configuration of the meander correction is a detection timing determination unit 81 that determines the detection timing of each sensor 6A, 6B, and a detection information capturing unit that captures the position information of each end face from each sensor 6A, 6B. 61, detection information storage unit 72 for temporarily storing first end surface position information captured from first sensor 6A, first end surface position information stored in detection information storage unit 72, and second information acquired from second sensor 6B. Based on the end face position information, the amount of deviation from the appropriate position is obtained, and a control amount calculation unit 73 that calculates the control amount of the meander correction actuator 436, and an actuator drive unit that drives the meander correction actuator 436 based on the calculated control amount. 435 is configured.

  These control configurations are driven by the control flow shown in FIGS. When the process is started in FIG. 8 and the take-in timing of the first sensor 6A is determined (S102), the first end face position information output from the first sensor 6A in the detection information take-in unit 71 is the detection information storage unit. 72 is temporarily stored (S103). Next, when the capture timing of the second sensor 6B is determined (S104), the detection information capture unit 71 outputs the second end face position information output by the second sensor 6B to the control amount calculation unit 73. .

  The control amount calculation unit 73 calculates the control amount of the meandering correction actuator 436 based on the first end face position information and the second end face position information (S106). The actuator driving unit 435 generates a driving current based on the calculated control amount, and drives the meandering correction actuator 436. By repeating the flow shown in FIG. 8, the position of the transfer material S in the width direction is corrected to an appropriate position.

  In the present embodiment, in particular, the take-in timing of the first sensor 6A and the second sensor 6B, specifically, the take-in interval of the first sensor 6A and the second sensor 6B is important. As described with reference to FIG. 6, the end face E of the transfer material is required to be detected at the same position or substantially the same position. Therefore, the take-in timing of each sensor 6A, 6B is determined in consideration of the conveyance of the transfer material S. FIG. 8 is a flowchart showing the acquisition timing determination process of each sensor 6A, 6B.

  When the process is started, the timing for taking in the first end face position information from the first sensor 6A is first determined (S202). Time counting is started from this capture timing (S203), and the passage of a predetermined time is determined (S204). The predetermined time is set so that the end surface of the transfer material detected by the first sensor 6A is detected by the second sensor 6B, and the process speed of the image forming apparatus, that is, the transfer speed of the transfer material S is taken into consideration. Determined. The conveyance speed is variably controlled according to the type of the transfer material S to be used and the printing accuracy. For this reason, the predetermined time determined in S204 is changed according to the type setting of the transfer material S and the print mode setting such as high-precision printing. When the elapse of the predetermined time is determined, the timing for taking in the second end face position information by the second sensor 6B is determined (S205).

In S206, it is determined whether or not the next capture is necessary, for example, when the control of the meandering correction unit 43 is no longer necessary, such as at the end of printing. If it is determined that no capture is necessary, the capture timing determination process is terminated (S208). On the other hand, if continuous capture is required, S2
In 07, a wait is applied until the next capture timing of the first sensor 6A is reached. The time required for this weight is a control interval for the meandering correction unit 43.

  As described above, in the present embodiment, the acquisition timing of the first sensor 6A and the second sensor 6B is determined by measuring time. In addition, the take-in timing may be determined by detecting the transfer distance (transfer amount) of the transfer material.

  FIG. 10 is a diagram showing a configuration of an image forming apparatus according to another embodiment of the present invention. In the present embodiment, the third roller 45 is provided with a rotary encoder 51 that detects the amount of rotation. The rotary encoder 51 detects the rotation amount, and the transport distance of the transfer material S is calculated in consideration of the diameter of the third roller 45. The take-in timing of the first sensor 6A and the second sensor 6B is determined based on this transport distance. Specifically, the end surface position information is captured from the second sensor 6B at the timing when the position of the end surface of the transfer material S captured from the first sensor 6A is conveyed to the detection position of the second sensor 6B.

  In this embodiment, the form of the transfer material S wound around the rollers 43a and 43b of the meandering correction unit 43 is different. Two rollers 44a and 44b that convey the transfer material S with the transfer material S interposed therebetween are disposed upstream of the image forming units 1Y to 1K. By performing such rotation control of the nip rollers 44a and 44b, it is possible to adjust the conveyance speed of the transfer material S.

  FIG. 11 is a block diagram showing a control configuration of meandering correction according to another embodiment of the present invention, and FIG. 12 is a flowchart showing detection timing determination processing according to another embodiment of the present invention. Here, differences from the above-described embodiment will be described. The rotary encoder 51 as the third sensor detects the rotation amount of the third roller 45. The transport distance measuring unit 82 calculates the transport distance of the transfer material S in consideration of the diameter of the third roller 45. The detection timing determination unit 83 takes in the first end face position information and the second end face position information respectively output from the first sensor 6A and the second sensor 6B based on the calculated transport distance. In the present embodiment, the rotary encoder 51 is used as a third sensor for measuring the transport distance of the transfer material S. However, the third sensor uses light or ultrasonic waves using the rough surface of the transfer material S. Various forms such as non-contact detection of the conveyance distance can be used.

  The timing for taking in information on the position of each end face is determined by the flow shown in FIG. When the process is started, the timing for taking in the first end face position information from the first sensor 6A is first determined (S302). Measurement of the rotation amount of the rotary encoder 51 is started from this take-in timing (S303). In S304, it is determined whether or not the transport distance calculated based on the rotation amount has reached a predetermined amount. The timing at which the second end face position information is taken in from the second sensor 6B when the transport distance reaches a predetermined amount, that is, when the transfer material S is transported by the distance between the detection positions of the first sensor 6A and the second sensor 6B. (S305).

  In S306, it is determined whether or not the next capture is necessary, for example, when the control of the meandering correction unit 43 is no longer necessary, for example, at the end of printing. If it is determined that the capture is not necessary, the capture timing determination process is terminated (3208). On the other hand, if it is necessary to continue the capture, a wait is applied until the next capture timing of the first sensor 6A is reached in S307. The time required for this weight is a control interval for the meandering correction unit 43. The acquisition timings of the sensors 6A and 6B determined by the above processing are used for drive control of the meandering correction unit 43 in the processing of the flowchart illustrated in FIG.

FIG. 13 is a diagram illustrating how the image forming unit and the first and second sensors are fixed according to the embodiment of the present invention. The first sensor 6A and the second sensor 6B are preferably positioned corresponding to the image forming units 1Y to 1K. Therefore, in the present embodiment, the first sensor 6A and the second sensor 6B are fixed to the fixed frame 52 to which the image forming units 1Y to 1K are fixed. The arrangement method of the sensors 6A and 6B may be employed for the embodiment described with reference to FIG.

  Note that although various embodiments have been described in this specification, embodiments configured by appropriately combining the configurations of the respective embodiments are also included in the scope of the present invention.

  1Y... Image forming section (hereinafter the same as Y, M, C, K) Y, Y: photoconductor (latent image carrier), 11Y: corona charger, 12Y: exposure Unit (exposure section), 18Y ... photosensitive member cleaning blade, 19Y ... transfer backup roller, 20Y ... developing roller (developer carrier), 21Y ... developing roller cleaning blade, 22Y ... toner charger (charger), 31Y ... development 311Y ... developer reservoir, 32Y ... intermediate roller, 33Y ... anilox roller, 34Y ... intermediate roller cleaning blade, 35Y ... regulating member, 41 ... unwinding shaft, 42 ... first roller, 43 ... meander correction Part, 43a ... front roller, 43b ... rear roller, 431a, 431b ... rotation axis, 432a, 432b ... rotation axis support 433 ... Frame, 434 ... Rotation fulcrum, 435 ... Actuator drive unit, 436 ... Meander correction actuator, 44 ... Second roller, 45 ... Third roller, 46 ... Fourth roller, 47 ... Winding shaft, 51 ... Rotary encoder 52 ... fixed frame, 6A ... first sensor, 6B ... second sensor, 61 ... support member, 62 ... light emitting part (oscillating part), 63 ... light receiving part (vibration receiving part), 71 ... detection information fetching part, 72 ... Detection information storage unit, 73 ... Control amount calculation unit, 81 ... Detection timing determination unit, 82 ... Conveyance distance calculation unit, 83 ... Detection timing determination unit

Claims (8)

A transport unit for transporting the transfer material;
A first image forming unit that forms an image on a transfer material conveyed by the conveying unit;
A second image forming unit that forms an image on the transfer material on which the image is formed by the first image forming unit;
A first sensor that detects a position of an end surface in the conveyance direction of the transfer material conveyed by the conveyance unit;
A second sensor that detects a position of an end surface in the transport direction of the transfer material that is transported by the transport unit and detected by the first sensor;
A transfer material position adjusting unit that adjusts a position in a direction orthogonal or substantially orthogonal to the transfer direction of the transfer material conveyed by the conveyance unit;
A timing determining unit for determining a timing for detecting the position of the end face of the transfer material by the second sensor based on the timing of detecting the position of the end face of the transfer material by the first sensor;
Based on the information on the position of the end face of the transfer material detected by the first sensor and the information on the position of the end face of the transfer material detected by the second sensor, the transfer material position adjustment unit performs the transfer. A control unit for adjusting the position of the material;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the transport unit transports the transfer material to a position where an image is formed by the image forming unit. The transport unit includes two rollers that stretch the transfer material at a position where an image is formed by the first image forming unit and the second image forming unit,
The image forming apparatus according to claim 1, wherein the first sensor and the second sensor are disposed between the two rollers that stretch the transfer material.   The timing at which the position of the end surface of the transfer material is detected by the second sensor is a timing at which a predetermined time has elapsed after the position of the end surface of the transfer material is detected by the first sensor. 4. The image forming apparatus according to any one of items 3.   The image forming apparatus according to claim 4, wherein the predetermined time used for determining a timing at which the position of the end face of the transfer material is detected by the second sensor is changed based on a conveyance speed of the transfer material. A third sensor for detecting a transfer distance of the transfer material;
The timing at which the end surface of the transfer material is detected by the second sensor is determined in advance by the third sensor after the position of the end surface of the transfer material is detected by the first sensor. The image forming apparatus according to any one of claims 1 to 3, wherein a timing at which the transported distance is detected is detected. A frame for fixing the image forming unit;
The image forming apparatus according to claim 1, wherein the first sensor and the second sensor are disposed on the frame. The position of the end surface in the conveyance direction of the transfer material conveyed by the conveyance unit is detected by the first sensor,
Based on the timing at which the position of the end surface of the transfer material is detected by the first sensor, the timing at which the position of the end surface of the transfer material is detected by the second sensor is determined, and the transported by the transport unit An image is formed on the transfer material by the first image forming unit,
The position of the end surface of the transfer material conveyed by the conveyance unit is detected by the second sensor at a determined timing,
Based on the position of the end surface of the transfer material detected by the first sensor and the position of the end surface of the transfer material detected by the second sensor, the transfer material transported by the transport unit An image forming method comprising adjusting a position of the transfer material in a direction orthogonal or substantially orthogonal to a conveyance direction, and forming an image on the transfer material conveyed by the conveyance unit by a second image forming unit. .

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