JP2010047353A - Image forming device and inclination correction method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain skew information of a recording paper with an inexpensive configuration without requiring a plurality of light receiving elements. <P>SOLUTION: An image forming device is equipped with a conveying means for delivering the recording paper from a paper feed tray, a waiting means which has a first detecting means for detecting the recording paper delivered by the conveying means, makes the recording paper wait and conveys it at a predetermined timing, and a second detecting means which horizontally moves a sensor vertically with respect to a conveying direction of the recording paper waiting by the waiting means and detects the inclination from the difference of the detecting time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that detects a tilt of a recording sheet and feeds back to laser lighting control, and a tilt correction method thereof.

  When an image is formed on a sheet in the image forming apparatus, if the sheet is conveyed to the image forming unit while being skewed, the image is printed obliquely with respect to the sheet.

  Therefore, in a conventional image forming apparatus, skew correction is performed by abutting and bending the front end of the paper against the nip portion of a registration roller disposed on the upstream side of the image forming unit, and the image is printed obliquely with respect to the paper. It was prevented from being done.

  However, such skew correction in the prior art has a problem that the paper skews due to disturbance factors such as slip of the transport roller while the paper is transported to the registration portion after the skew is corrected by the transport roller. .

Therefore, for example, in Patent Document 1, in order to prevent the sheet skew from occurring after skew correction, a guide for correcting the guide width to be equal to that of the recording medium based on the recording medium information detected by the detecting means. The invention with the means is described.
JP 2006-256803 A

  However, the invention described in Patent Document 1 requires a plurality of light receiving elements of the recording medium information detection sensor to be used, and has a width equal to or larger than the maximum printable width of the apparatus. End up.

  Accordingly, the present invention has been made in view of the above problems, and an object thereof is to provide an image forming apparatus that acquires skew information of a recording paper with an inexpensive configuration without requiring a plurality of light receiving elements. To do.

  In order to solve the above problems, an image forming apparatus according to the present invention includes a transport unit that feeds recording paper from a paper feed tray, and a first detection unit that detects the recording paper fed by the transport unit. A standby unit that waits and conveys at a predetermined timing, and a second sensor that horizontally moves the sensor perpendicular to the conveyance direction of the recording paper that is waiting by the standby unit, and detects a tilt from a difference in detection time. And a detecting means.

  The second detection means is characterized in that detection is always performed by starting movement from the same position.

  The second detection means is characterized in that the detection is performed alternately on the outward path or the return path for each recording sheet.

  The second detecting means has a light emitting means for emitting light and a light receiving means for receiving and detecting the light reflected on the recording paper, and the light emitting means and the light receiving means move together. It is characterized by doing.

  The image forming apparatus includes: a correction unit that generates inclination correction data for correcting the inclination of the recording paper with reference to a detection result by the second detection unit, and forms an image having no inclination.

  According to the inclination correction method of the image forming apparatus of the present invention, the conveyance step of feeding the recording paper from the paper feed tray, the first detection step of detecting the recording paper sent in the conveyance step, and the recording paper are made to wait. A standby step of transporting at a predetermined timing, and a second detection step of detecting the tilt from the difference in detection time by horizontally moving the sensor perpendicularly to the transport direction of the recording paper waiting in the standby step. It is characterized by providing.

  In the second detection step, detection is always performed by starting movement from the same position.

  The second detection step is characterized in that detection is performed alternately on the forward path or the return path for each recording sheet.

  In the second detection step, a light emitting unit having a light emitting step for emitting light and a light receiving unit having a light receiving step for receiving and detecting light reflected on the recording paper are moved together. Features.

  A correction step for generating tilt correction data for correcting the tilt of the recording paper with reference to the detection result of the second detection step to form an image without tilt is provided.

  According to the present invention, by moving the light receiving element and reading the paper width, it is possible to acquire skew information with an inexpensive configuration without requiring a plurality of light receiving elements.

  FIG. 1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention. This image forming apparatus is a tandem type, and includes a transfer belt 5, process cartridges (6Bk, 6M, 6C, 6Y) for each color, and an image forming unit corresponding to each color.

  The transfer belt 5 is endless and includes a secondary transfer driving roller 7 and a transfer belt tension roller 8 at both ends. The secondary transfer drive roller 7 is driven to rotate by a drive motor (not shown), and the transfer belt 5 is moved counterclockwise in the drawing by the rotation of the transfer belt tension roller 8.

  On the other hand, the process cartridges are arranged in the order of 6Bk, 6M, 6C, and 6Y in order from the upstream side in the rotation direction of the transfer belt 5.

  The process cartridges 6Bk, 6M, 6C, and 6Y have different toner image colors, but all have the same internal configuration. The process cartridge 6Bk forms a black image, the process cartridge 6M forms a magenta image, the process cartridge 6C, a cyan image, and the process cartridge 6Y forms a yellow image.

  Hereinafter, the image forming unit Bk located on the most upstream side in the rotation direction of the transfer belt 5 will be described in detail. Since the other image forming units M, C, and Y have the same configuration as the image forming unit Bk, the components of the image forming units M, C, and Y are the same as the components of the image forming unit Bk. Instead of the attached Bk, only the symbols distinguished by M, C, and Y are displayed in the figure, and the description is omitted.

  The image forming unit Bk includes a photoreceptor 9Bk, a charger 10Bk, an exposure unit 11, a developing unit 12Bk, and a cleaner blade 13Bk. The exposure unit 11 is configured to irradiate laser beams 14Bk, 14M, 14C, and 14Y corresponding to the image colors formed by the image forming units Bk, M, C, and Y, respectively.

  The photoreceptor 9Bk is uniformly charged on the outer peripheral surface by a surrounding electric body 10Bk, and then exposed to a laser beam 14Bk corresponding to a black image from the exposure unit 11, thereby forming an electrostatic latent image. The

  The developing device 12Bk visualizes the formed electrostatic latent image with black toner, thereby forming a black toner image on the photoreceptor 9Bk.

  The formed toner image is transferred onto the transfer belt 5 by the action of the primary transfer roller 15Bk at a position (primary transfer position) where the photoreceptor 9Bk and the transfer belt 5 are in contact with each other, thereby forming an image with black toner.

  The cleaner blade 13Bk wipes unnecessary toner remaining on the outer peripheral surface of the photoconductor 9Bk after the transfer of the toner image is completed for the next image formation.

  As described above, the transfer image to which the black toner image is transferred by the image forming unit Bk is conveyed to the next image forming unit M. In the image forming unit M, a magenta toner image is formed on the photoconductor 9M by a process similar to the image forming process in the image forming unit Bk, and is transferred onto the black image formed on the transfer belt 5 in a superimposed manner. The

  The transfer belt 5 is further conveyed to the next image forming portions C and Y, and a cyan toner image formed on the photoconductor 9C and a yellow toner image formed on the photoconductor 9Y by the same operation. Are superimposed and transferred onto the transfer belt. Thus, a full-color image is formed on the transfer belt 5, and the transfer belt 5 on which the full-color image is formed is conveyed to the position of the secondary transfer roller 16.

  In the image formation, in the case of printing only black, the primary transfer roller 15M, the primary transfer roller 15C, and the primary transfer roller 15Y are retracted to positions separated from the photoconductor 9M, photoconductor 9C, and photoconductor 9Y, respectively. The above-described image forming process is performed only for black.

  When the recording paper is transported during image formation, the recording paper 4 stored in the paper feed tray 1 is sequentially sent out by rotating the paper feed roller 2 counterclockwise from the top, and the registration roller 3 position. Wait at

  The registration roller 3 starts to be driven at the timing at which the toner image and the recording paper 4 overlap each other on the toner image conveyed by the transfer belt 5 and the secondary transfer roller 16. At this time, the registration roller 3 feeds the recording paper 4 by being driven to rotate counterclockwise.

  The toner image on the transfer belt 5 is transferred to the recording paper 4 delivered by the registration roller 3 by the secondary transfer roller 16. Thereafter, the toner image is fixed by heat and pressure in the fixing unit 17 and discharged to the outside of the image forming apparatus by a discharge roller 18 that is driven to rotate counterclockwise.

  Next, the recording paper tilt detection method in the present embodiment will be described in detail.

  A registration sensor 20 serving as a reference for timing for driving and stopping the paper feed roller 2 is provided on the upstream side of the paper feed roller 2 in the paper conveyance direction, and a skew sensor 21 is provided in the vicinity thereof.

  FIG. 2 is a configuration diagram of the skew sensor according to the embodiment of the present invention. The skew sensor 21 is an optical sensor and includes a light emitting unit 30 and a light receiving unit 31.

  When the recording paper 4 is on the optical path emitted from the light emitting unit 30, the light is reflected by the recording paper 4 and incident on the light receiving unit 31 to detect the presence of the recording paper 4. On the other hand, when the recording paper 4 is not on the optical path, the light emitted from the light emitting unit 30 is reflected and does not enter the light receiving unit 31, so that the absence of the recording paper 4 can be detected.

  FIG. 3 is a diagram illustrating the movement operation of the skew sensor. The skew sensor 21 is attached to a skew belt 40 that is long in a direction perpendicular to the conveyance direction of the recording paper 4. The skew belt 40 is configured to be sufficiently longer than the width of the recording paper 4 in the short direction, and the skew sensor 21 can move from end to end of the recording paper 4.

  The skew belt 40 moves at a constant speed by driving a stepping motor (not shown), and accordingly, the skew sensor 21 moves at a constant speed.

  FIG. 4A is a schematic diagram when the recording paper 4 is conveyed vertically without being inclined with respect to the registration roller 3. The recording paper 4 transported without tilting stands by at a position where the leading edge is brought into contact with the registration roller 3.

  The skew sensor 21 moves from the left of the recording paper 4 to the right perpendicular to the transport direction of the recording paper 4 waiting at the position where the tip of the registration sensor 3 is in contact with the registration roller 3. That is, the skew sensor 21 starts to move in the paper direction from the home position A outside the recording paper 4, passes through the recording paper 4, and then moves to the home position B outside the paper.

  A schematic diagram of the output waveform of the skew sensor 21 when the recording paper 4 is conveyed without being inclined with respect to the registration roller 3 is shown in FIG. When the skew sensor 21 moves on the recording paper 4 and detects the recording paper 4, the output waveform level is high. That is, the time from when the detection level becomes high until it becomes low can be detected as the recording paper detection time T1.

  On the other hand, FIG. 5A is a schematic diagram when the recording paper 4 is conveyed while being inclined with respect to the registration roller 3. The recording paper 4 that is conveyed in an inclined state stands by at a position where the corner portion is in contact with the registration roller 3.

  Similarly, the skew sensor 21 moves vertically from the left to the right of the recording paper 4 with respect to the conveyance direction of the recording paper 4 that stands by at the position where the corner portion is in contact with the registration roller 3. That is, the skew sensor 21 starts to move in the paper direction from the home position A ′ outside the recording paper 4, passes through the recording paper 4, and then moves to the home position B ′ outside the paper.

  FIG. 5B shows a schematic diagram of an output waveform of the skew sensor 21 when the recording paper 4 is conveyed while being inclined with respect to the registration roller 3. When the skew sensor 21 moves on the recording paper 4 and detects the recording paper 4, the output waveform level is high. That is, the time from when the detection level is increased to when the detection level is decreased can be detected as the recording paper detection time T2.

  When the recording paper is tilted, the skew sensor 21 crosses the paper diagonally, so the recording paper detection time T2 when there is a tilt is T2 with respect to the recording paper detection time T1 when there is no tilt. The relationship> T1 holds.

  Here, assuming that the moving speed of the skew sensor 21 is V as shown in FIG. 6, the inclination width S when the recording paper 4 is inclined can be obtained by the following equation.

  By storing T1 for each standard recording paper size in advance and obtaining the inclination width S from the above equation, it can be determined that there is an inclination when S ≠ 0. By sending the information of the inclination width S thus obtained to the laser lighting control unit and controlling the timing of laser writing, it is possible to form an image without inclination even if the recording paper 4 is inclined. Become.

  Further, the moving direction of the skew sensor is not limited to the above configuration, and may be detected from the reverse direction. FIG. 7A is a schematic diagram when the recording paper 4 is conveyed vertically without being inclined with respect to the registration roller 3. The recording paper 4 transported without tilting stands by at a position where the leading edge is brought into contact with the registration roller 3.

  The skew sensor 21 moves from the right to the left of the recording paper 4 perpendicular to the transport direction of the recording paper 4 waiting at the position where the tip of the registration sensor 3 is in contact with the registration roller 3. That is, the skew sensor 21 starts to move in the paper direction from the home position A outside the recording paper 4, passes through the recording paper 4, and then moves to the home position B outside the paper.

  FIG. 7B shows a schematic diagram of the output waveform of the skew sensor 21 when the recording paper 4 is conveyed without being inclined with respect to the registration roller 3. When the skew sensor 21 moves on the recording paper 4 and detects the recording paper 4, the output waveform level is high. That is, the time from when the detection level becomes high until it becomes low can be detected as the recording paper detection time T1.

  On the other hand, FIG. 8A is a schematic diagram when the recording paper 4 is conveyed while being inclined with respect to the registration roller 3. The recording paper 4 that is conveyed in an inclined state stands by at a position where the corner portion is in contact with the registration roller 3.

  Similarly, the skew sensor 21 moves from the right to the left of the recording paper 4 perpendicularly to the conveyance direction of the recording paper 4 waiting at a position where the corner portion of the registration roller 3 is abutted. That is, the skew sensor 21 starts to move in the paper direction from the home position A ′ outside the recording paper 4, passes through the recording paper 4, and then moves to the home position B ′ outside the paper.

  FIG. 8B shows a schematic diagram of an output waveform of the skew sensor 21 when the recording paper 4 is conveyed while being inclined with respect to the registration roller 3. When the skew sensor 21 moves on the recording paper 4 and detects the recording paper 4, the output waveform level is high. That is, the time from when the detection level is increased to when the detection level is decreased can be detected as the recording paper detection time T2.

  When the recording paper is tilted, the skew sensor 21 crosses the paper diagonally, so the recording paper detection time T2 when there is a tilt is T2 with respect to the recording paper detection time T1 when there is no tilt. > T1 holds, and the inclination width S when the recording paper 4 is inclined can be obtained with the moving speed of the skew sensor 21 as V as described above.

  By sending the information of the inclination width S thus obtained to the laser lighting control unit and controlling the timing of laser writing, it is possible to form an image without inclination even if the recording paper 4 is inclined. Become.

  FIG. 9 is a flowchart of tilt detection correction of the image forming apparatus according to the embodiment of the present invention.

  When a print request is made (step S101), the recording paper is fed to the registration roller position (step S102). When a part (front end) of the recording paper reaches the registration roller position, the inclination state of the recording paper is detected (step S103).

  It is determined whether the value detected by the tilt state detection is a tilt that needs to be corrected (step S104). If it is determined that the tilt correction is necessary, the laser lighting control unit generates tilt correction data. After (step S105), the laser is turned on to generate an electrostatic latent image on the photoreceptor (step S106).

  On the other hand, if it is determined that tilt correction is unnecessary, the laser is turned on without generating tilt correction data, and an electrostatic latent image is generated on the photosensitive member (step S106).

  In both the operations after step S106, the toner image is generated on the photosensitive member by the developing device (step S107) and transferred to the intermediate transfer belt (step S108). Thereafter, transfer is performed on the recording paper (step S109), and the image transferred by the fixing device is fixed (step S110).

  On the other hand, FIG. 10 is a flowchart of tilt detection correction of the image forming apparatus in another embodiment of the present invention.

  In the above-described embodiment, for the tilt correction using the skew sensor, the intermediate transfer method is used in which the toner image formed on the photosensitive member is transferred onto the transfer belt and then transferred onto the recording paper. In the embodiment, a direct transfer method in which a toner image formed on a photoreceptor is directly transferred to a recording sheet will be described.

  When a print request is made (step S201), the recording paper is fed to the registration roller position (step S202). When a part (front end) of the recording paper reaches the registration roller position, the inclination state of the recording paper is detected (step S203).

  It is determined whether the value detected by the tilt state detection is a tilt that needs to be corrected (step S204). If it is determined that the tilt correction is necessary, the laser lighting control unit generates tilt correction data. After (step S205), the laser is turned on to generate an electrostatic latent image on the photosensitive member (step S206).

  On the other hand, if it is determined that tilt correction is unnecessary, the laser is turned on without generating tilt correction data, and an electrostatic latent image is generated on the photosensitive member (step S206).

  In both the operations after step S206, similarly, in both cases, a toner image is generated on the photosensitive member by the developing device (step S207), and the toner image generated on the photosensitive member is directly transferred onto the recording sheet (step S208). ). The image transferred to the recording paper is fixed by the fixing device (step S209).

  The detection direction of the skew sensor 21 need not be limited to a specific direction. For example, the detection may be performed when returning from the home position B ′ outside the paper to the home position A ′.

  In other words, when recording paper is continuously fed, first the first sheet moves perpendicularly to the recording paper transport direction from left to right and detects the tilt. The inclination of the recording sheet is detected by moving the recording sheet from right to left perpendicular to the recording sheet conveyance direction.

  By moving the third and subsequent sheets alternately from left to right and from right to left, it is not necessary to return to the original home position for each sheet, and the time can be shortened.

  The present invention has been described above by the preferred embodiments of the present invention. While the invention has been described with reference to specific embodiments thereof, various modifications and changes can be made to these embodiments without departing from the broader spirit and scope of the invention as defined in the claims. is there.

1 is a configuration diagram of an image forming apparatus according to an embodiment of the present invention. It is a block diagram of the skew sensor which concerns on embodiment of this invention. It is a schematic diagram of the movement operation | movement of the skew sensor which concerns on embodiment of this invention. FIG. 6 is a schematic diagram when the recording paper is conveyed without being inclined. FIG. 6 is a schematic diagram when a recording sheet is conveyed while being inclined. It is a figure explaining inclination width S when a recording paper inclines. FIG. 6 is a schematic diagram when the recording paper is conveyed without being inclined. FIG. 6 is a schematic diagram when a recording sheet is conveyed while being inclined. 1 is a flowchart of an image forming apparatus according to an embodiment of the present invention. It is a flowchart figure of the image forming apparatus which concerns on other embodiment of this invention.

Explanation of symbols

4 Recording paper 21 Skew sensor 30 Light emitting part 31 Light receiving part 40 Skew belt

Claims (10)

Conveying means for feeding recording paper from the paper feed tray;
A first detecting means for detecting the recording paper sent out by the conveying means; a waiting means for waiting the recording paper and conveying it at a predetermined timing;
An image comprising: a second detection unit that horizontally moves a sensor perpendicular to a conveyance direction of the recording paper that is waiting by the standby unit, and detects an inclination from a difference in detection time. Forming equipment.   The image forming apparatus according to claim 1, wherein the second detection unit always starts detection from the same position.   The image forming apparatus according to claim 1, wherein the second detection unit performs detection on the forward path or the return path alternately for each recording sheet. The second detection means includes light emitting means for emitting light and light receiving means for receiving and detecting the light reflected on the recording paper,
The image forming apparatus according to claim 1, wherein the light emitting unit and the light receiving unit move together.   2. The image forming apparatus according to claim 1, further comprising: a correction unit that generates inclination correction data for correcting the inclination of the recording paper and forms an image without inclination with reference to a detection result of the second detection unit. 5. The image forming apparatus according to any one of items 1 to 4. A transport step for feeding the recording paper out of the paper feed tray;
A first detection step of detecting the recording paper sent out in the transport step;
A standby step of waiting the recording paper and transporting it at a predetermined timing;
And a second detection step of detecting a tilt from a difference in detection time by horizontally moving a sensor perpendicularly to the conveyance direction of the recording paper waiting in the standby step. Device tilt correction method.   7. The inclination correction method for an image forming apparatus according to claim 6, wherein in the second detection step, detection is always performed by starting movement from the same position.   7. The method of correcting an inclination of an image forming apparatus according to claim 6, wherein in the second detection step, detection is alternately performed in the forward path or the backward path for each recording sheet.   In the second detecting step, a light emitting unit having a light emitting step for emitting light and a light receiving unit having a light receiving step for receiving and detecting the light reflected on the recording paper are moved together. The tilt correction method for an image forming apparatus according to claim 6, wherein the tilt correction method is used.   7. A correction step of generating inclination correction data for correcting the inclination of the recording paper with reference to the detection result of the second detection step to form an image without inclination. The inclination correction method for an image forming apparatus according to any one of claims 1 to 9.

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