JP2007152717A - Light exposing apparatus and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light exposing apparatus which suppresses variation of magnification in the main scanning direction caused by thermal expansion of a light emitting element array, and keeps the quality of an image in the outputted image, and an image forming apparatus having this light exposing apparatus. <P>SOLUTION: The light exposing apparatus 62 which irradiates a photo-conductor 58 with a light to write a latent image, has an LED array 90 consisting of a plurality of LEDs 88 aligned and arranged, and an adjusting means 98 for adjusting the relative angle between the photo-conductor 58 and the LED array 90 in accordance with the length in the main scanning direction of this LED array 90. More practically, the adjusting means 98 changes an angle of the LED array 90 to the photo-conductor 58 around a rotating shaft 96 as a center provided in the vertical direction in the rotating shaft direction of the photo-conductor 58. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an exposure apparatus and an image forming apparatus having the image forming unit.

  2. Description of the Related Art In an exposure apparatus that writes a latent image by irradiating light onto a photoconductor, an exposure apparatus that uses a light emitting element array unit (LED array) in which light emitting elements such as LEDs (light emitting diodes) are aligned is known (for example, Patent Document 1).

JP-A-10-31348

  However, in the invention disclosed in Patent Document 1, the length of the LED array in the main scanning direction varies due to thermal expansion due to heat generation of the light emitting portion and the substrate of the LED array, and the width of the image written on the photoreceptor ( (Scanning range) may fluctuate, that is, magnification fluctuations in the main scanning direction may occur.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an exposure apparatus that suppresses magnification fluctuations in the main scanning direction due to thermal expansion of a light emitting element array and maintains image quality in an output image, and an image forming apparatus having the exposure apparatus. is there.

  In order to achieve the above object, a first feature of the present invention is an exposure apparatus for irradiating a photosensitive member with light to write a latent image, which is a light emitting element array comprising a plurality of light emitting elements arranged in alignment. And an adjusting device that adjusts the relative angle between the photoconductor and the light emitting element array in accordance with the length variation of the light emitting element array in the main scanning direction. Accordingly, the magnification fluctuation in the main scanning direction is suppressed, and the image quality in the output image is maintained.

  Preferably, the light emitting element is an LED (light emitting diode).

  Preferably, the adjusting means changes an angle of the light emitting element array with respect to the photosensitive member around a rotation axis provided in a direction perpendicular to the axial direction of the photosensitive member. Therefore, the magnification deviation in the main scanning direction is suppressed.

  Preferably, the adjusting means changes the angle of the light emitting element array with respect to the photosensitive member around a rotation axis provided in a direction parallel to the axial direction of the photosensitive member. Therefore, the magnification deviation in the main scanning direction is suppressed.

  Preferably, the rotation shaft is disposed at at least one position near the center and the end in the main scanning direction of the light emitting element array. Therefore, the angle of the light emitting element array with respect to the photosensitive member can be changed.

  Preferably, the adjusting means includes an arm member provided in the vicinity of at least one end of the light emitting element array. Therefore, the angle of the light emitting element array with respect to the photoconductor is adjusted with a simple structure.

  A second feature of the present invention is that it includes a photoconductor and an exposure device that irradiates the photoconductor with light and writes a latent image, and the exposure device includes a plurality of light emitting elements arranged in an array. And an adjusting unit that adjusts a relative angle between the photosensitive member and the light emitting element array according to a length variation in the main scanning direction of the light emitting element array. is there. Accordingly, the magnification fluctuation in the main scanning direction is suppressed, and the image quality in the output image is maintained.

  Preferably, a control unit that controls writing timing in the plurality of light emitting elements according to a length variation of the light emitting element array in the main scanning direction is provided. Therefore, it is possible to correct a skew deviation caused by a change in the angle of the light emitting element array with respect to the photosensitive member.

  Preferably, the image processing device includes image processing means for performing image processing on the image data in accordance with a length variation of the light emitting element array in the main scanning direction. Therefore, it is possible to correct a skew deviation caused by a change in the angle of the light emitting element array with respect to the photosensitive member.

  According to the present invention, the relative angle between the photoconductor and the light emitting element array is adjusted in accordance with the variation in the length of the light emitting element array in the main scanning direction, so that the magnification in the main scanning direction due to the thermal expansion of the light emitting element array is adjusted. The fluctuation is suppressed, and the image quality in the output image can be maintained.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12, and an intermediate transfer belt 14 is disposed in the image forming apparatus main body 12. For example, four image forming units 16 are arranged in parallel to the intermediate transfer belt 14, and the image forming apparatus 10 is a so-called tandem system. The image forming unit 16 forms toner images of yellow (Y), magenta (M), cyan (C), and black (K) on the intermediate transfer belt 14, respectively.

  A sheet supply device 18 is provided below the image forming apparatus main body 12. The sheet supply device 18 includes a sheet supply cassette 20 on which sheets are stacked, a pickup roll 22 that picks up the sheets stacked on the sheet supply cassette 20, and a feed roll 24 and a retard roll 26 that send out the sheets while rolling them. . The sheet supply cassette 20 is provided detachably with respect to the image forming apparatus main body 12, and a sheet as a transfer medium such as plain paper or an OHP sheet is stacked and stored.

  Near one end of the image forming apparatus main body 12 (near the left end in the figure), a sheet supply path 28 is provided substantially along the vertical direction. In the sheet supply path 28, a transport roll 29, a resist roll 30, a secondary transfer roll 32, a fixing device 34 and a discharge roll 36 are provided. The registration roll 30 temporarily stops the sheet sent to the sheet supply path 28 and sends it to the secondary transfer roll 32 at a timing. The fixing device 34 includes a heating roll 34a and a pressure roll 34b, and fixes the toner image on the sheet by applying heat and pressure to the sheet passing between the heating roll 34a and the pressure roll 34b. ing.

  A discharge tray section 38 is provided on the upper part of the image forming apparatus main body 12. The sheet having the toner image fixed thereon is discharged onto the discharge tray portion 38 by the discharge roll 36 described above, and is stacked on the discharge tray portion 38. Accordingly, the sheets in the sheet supply cassette 20 are sequentially discharged to the discharge tray unit 38 through a C-shaped path.

  For example, four toner bottles 40 are provided on the other end side (right end side in the figure) of the image forming apparatus main body 12. The toner bottle 40 contains yellow, magenta, cyan, and black toners, and supplies the toner to the image forming unit 16 via a toner supply path (not shown).

  The intermediate transfer belt 14 is supported by a plurality of conveyance rolls 42, and the belt surface on which the image forming unit 16 is provided is inclined with respect to the horizontal direction. One of the transport rolls 42 constitutes a backup roll for the secondary transfer roll 32. An intermediate belt cleaning device 44 is disposed in the vicinity of the upper end of the intermediate transfer belt 14, and the other one of the transport rolls 42 constitutes a backup roll of the cleaning device 44. Further, a tension roll 46 is disposed above the intermediate transfer belt 14, and an appropriate tension is applied to the intermediate transfer belt 14 by the tension roll 46.

  The image forming unit 16 includes an image forming unit 48 provided on one surface of the intermediate transfer belt 14 and a primary transfer roll 50 provided on the back surface of the intermediate transfer belt 14. The image forming unit 48 is detachable with respect to the image forming apparatus main body 12, and once moved downward, it can be pulled out in the front direction in the figure.

  A control device 52 and an image processing device 54 are disposed in the image forming apparatus main body 12. The control device 52 controls the operation of each device in the image forming apparatus main body 12, and the image processing device 54 is personalized via data input from an image reading device (not shown) or a network line such as a LAN. The image data input from a computer (not shown) or the like is subjected to predetermined image processing to be described later.

  In FIG. 2, details of the image forming means 16 are shown. The image forming unit 48 includes a unit main body 56, a photoconductor 58 facing the intermediate transfer belt 14 on the unit main body 56, a charging device 60 configured by, for example, a roll for charging the photoconductor 58, and the like, for example An exposure device 62 that is composed of an LED (light emitting diode) and irradiates light onto the photoconductor 58 to form (write) a latent image, and a latent image on the photoconductor 58 formed by the exposure device 62. A developing device 64 that develops the image with toner and a cleaning device 66 that cleans the toner remaining on the photoreceptor 58 after the transfer are housed. A temperature sensor 68 for detecting the temperature of the LED array 90 of the exposure device 62 described later is disposed in the vicinity of the exposure device 62 in the image forming unit 56.

  The developing device 64 is, for example, a two-component system, and uses a developer composed of toner and a carrier. For example, the developing device 64 is disposed in two upper augers 70 and 72 arranged in parallel in the horizontal direction and obliquely above the discharge-side auger 72. The developer is agitated by the augers 70 and 72 and supplied to the developer roll 74. In the developing roll 74, a magnetic brush is formed by a carrier, the toner attached to the carrier is conveyed by the magnetic brush, and the latent image on the photoconductor 58 is developed by the toner.

  The cleaning device 66 includes a cleaning roll 76 and a cleaning brush 78. The cleaning roll 76 is provided so as to be able to rotate while being in contact with the photoconductor 58, and the cleaning brush 78 is disposed upstream of the cleaning roll 76 in the rotation direction of the photoconductor 58 so as to be in contact with the photoconductor 58. ing. The cleaning brush 78 adsorbs residual toner adhering to the surface of the photoconductor 58 to the cleaning brush 78 or scrapes it off to the downstream side in the rotation direction of the cleaning brush 78 to remove it. The cleaning roll 76 adsorbs and removes the toner remaining on the surface of the photoconductor 58 without being removed by the cleaning brush 78 from the photoconductor 58.

  In the above configuration, the intermediate transfer belt 14 and the photoconductor 58 rotate in opposite directions in synchronization with each other, the surface of the photoconductor 58 is charged by the charging device 60, and a latent image is formed (written) by the exposure device 62. ). The latent image on the photoconductor 58 formed by the exposure device 62 is developed by the developing device 64. The toner image developed by the developing device 64 is transferred to the intermediate transfer belt 14 by the primary transfer roll 50. The toner images of the respective colors formed by the image forming units 16 are superimposed as the intermediate transfer belt 14 moves.

  On the other hand, the sheets stacked on the sheet supply cassette 20 of the sheet supply apparatus 18 are fed one by one to the sheet supply path 28 by the pickup roll 22, the feed roll 24, the retard roll 26, and the like. The sheet sent to the sheet supply path 28 comes into contact with the registration roll 30, is temporarily stopped, and is sent to the secondary transfer roll 32 at a timing. The toner image on the intermediate transfer belt 14 is transferred to the sheet by the secondary transfer roll 32. The sheet on which the toner image has been transferred is further sent to the fixing device 34, where the toner image is fixed to the sheet by heat and pressure. The sheet on which the toner image is fixed by the fixing device 34 is discharged to the discharge tray portion 38 by the discharge roll 36.

Next, details of the exposure apparatus 62 will be described.
3 and 4, details of the exposure apparatus 62 are shown. As shown in FIG. 3, the exposure apparatus 62 has an exposure apparatus main body 82, and a control substrate 84 is disposed at the rear part (lower side in FIG. 3) of the exposure apparatus main body 82. In the exposure apparatus main body 82, an optical path forming hole 86 that opens toward the photoconductor 58 (shown in FIG. 3) is formed, and a plurality of light emitting elements (LEDs 88) are provided at the back end of the optical path forming hole 86. An LED array 90 arranged in parallel with the rotation axis direction of 58 is arranged. In addition, a rod lens array 92 is provided at the tip of the optical path forming hole 86 in a row in parallel with the rotation axis direction of the photoconductor 58. The rod lens array 92 condenses the light from the LED array 90 and forms an image on the photosensitive member 22. The control board 84 is mounted with a drive circuit for driving the LED array 90, a stabilization circuit for stabilizing the drive current, and the like, and the LED array via a harness (cable for transmitting a signal) 94. 90.

  FIG. 4 shows the photoconductor 58 and the exposure device 62 as viewed from above the photoconductor 58. As shown in FIG. 4, the LED array 90 is provided so that the relative angle between the LED array 90 and the photoconductor 58 can be adjusted. Specifically, the LED array 90 is provided so as to be rotatable about a rotation shaft 96 provided in a direction perpendicular to the rotation axis direction of the photoconductor 58. More specifically, as shown in FIG. 4A, a rotation shaft 96 is provided at a position in the vicinity of one end of the LED array 90 in the main scanning direction. When a load (for example, F1 in FIG. 5 (a)) is applied in the vicinity of the end opposite to the side on which the is provided, it rotates about the rotation shaft 96 (for example, in the direction of arrow A1 in FIG. 5 (a)). Rotation). Further, as shown in FIG. 4B, a rotation shaft 96 may be provided at the center position of the LED array 90 in the main scanning direction. In this case, when a load (for example, FIG. 5B) F2 is applied in opposite directions at both ends of the LED array 90, the LED array 90 rotates about the rotation shaft 96 (for example, an arrow in FIG. 5B). (Turns in the A2 direction). As described above, the angle of the LED array 90 with respect to the photosensitive member 58 is changed around the rotation shaft 96. The other end (lower end) of the rotation shaft 96 is rotatably provided in the image forming unit main body 56 as shown in FIG.

Next, magnification variation (magnification deviation in the main scanning direction) due to thermal expansion of the LED array 90 will be described.
FIG. 5 is a diagram for explaining the magnification deviation in the main scanning direction. As shown in FIG. 5A, when the length of the LED array 90 in the main scanning direction is increased (thermal expansion) due to heat generated by the LEDs 88 of the LED array 90, the control board 84, and the like, the LED array 90 The range on the photoconductor 58 to be scanned changes from “scanning range A” to “scanning range B” as shown in FIG. 5B, so that a magnification shift in the main scanning direction occurs.

Thus, when a deviation in magnification in the main running direction due to thermal expansion of the LED array 90 occurs, the LED array 90 is centered on a rotation axis 96 provided in a direction perpendicular to the rotation axis direction of the photoconductor 58 (a predetermined angle ( For example, by rotating the angle θ in FIG. 5C, it is possible to scan within the scanning range A on the photosensitive member 58 (within the scanning range before thermal expansion in the LED array 90), and the magnification in the main scanning direction. Deviation is suppressed.
For example, in the case where the length of the LED array 90 in the main scanning direction is about 300 mm, when the LED array 90 is thermally expanded by about 0.1 mm in the main scanning direction, the LED array 90 after this thermal expansion is By rotating about 1.5 degrees (angle θ in FIG. 5C) about a rotation shaft 96 provided perpendicular to the rotation axis direction, the magnification deviation in the main scanning direction on the photoconductor 58 is almost eliminated. can do.

  As shown in FIG. 5C, when the LED array 90 is rotated about a rotation shaft 96 provided in a direction perpendicular to the rotation axis direction of the photoconductor 58, the magnification deviation in the LED 90 is suppressed. On the other hand, there is a case where the irradiation light irradiated onto the photoconductor 58 is inclined with respect to the rotation axis direction of the photoconductor 58 and so-called “skew deviation” occurs in the output image. A method of correcting this “skew deviation” will be described later.

Next, an example of adjusting means for adjusting the angle of the LED array 90 with respect to the photoconductor 58 will be described.
In FIG. 6, an adjusting means 98 for rotating the LED array 90 is shown. As shown in FIG. 6A, the adjusting means 98 includes the above-described rotation shaft 96 and, for example, two arm portions 100 a and 100 b provided near the end of the LED array 90. One end of each of the arm portions 100a and 100b is swingably provided in the vicinity of the end portion of each LED array 90 (is swingable in the directions of arrows C1 and C2 in FIG. 6). The other end is slidably engaged with, for example, the image forming unit main body 56 (slidable in the directions of arrows B1 and B2 in FIG. 6). These arm portions 100a and 100b are provided at point-symmetrical positions with the rotation shaft 96 of the LED array 90 as a fulcrum.

  As shown in FIG. 6B, the LED array 90 is thermally expanded (the length of the LED array 90 in the main scanning direction is increased. Specifically, the length of the LED array 90 in the main scanning direction is as shown in FIG. From L in a) to L + 2 × L1 in FIG. 6B, the engaging portion between the LED array 90 and the arm portions 100a and 100b moves to the image forming unit main body 56 side (in FIG. 6B). Move in the direction of arrows D1 and D2. By moving the engaging portion between the LED array 90 and the arm portions 100a and 100b, from the LED array 90 side to the image forming unit main body 56 side in the arm portions 100a and 100b (in the directions of arrows E1 and E2 in FIG. 6B) F) Force will be applied.

As shown in FIG. 6C, the arm portions 100a, 100b, the main unit 33, and the arm unit 100a, 100b due to the force acting on the arm portions 100a, 100b due to the thermal expansion (length variation in the main scanning direction) of the LED array 90 described above. Are moved along the wall surface of the image forming unit main body 56 (moved in the directions of arrows G1 and G2 in FIG. 6C). As a result, the LED array 90 rotates a predetermined angle (rotates in the direction of arrow A2) with the rotation shaft 96 as a fulcrum. Specifically, in the LED array 90, the scanning range in the rotation axis direction of the photoreceptor 58 in the LED array 90 after thermal expansion is the length in the main scanning direction in the LED array 90 before thermal expansion (FIG. 6A). (L) of FIG. 6 (c). At this time, when the length of the LED array 90 in the main scanning direction varies (L1 in FIG. 6B varies), the rotation angle (the angle θ in FIG. 6C) varies according to the variation amount. .
Thus, with a simple structure, the relative angle between the LED array 90 and the photosensitive member 58 is adjusted according to the variation in the length of the LED array 90 in the main scanning direction. Thereby, the fluctuation | variation of the magnification of the main scanning direction by the thermal expansion of the LED array 90 can be suppressed.

Next, a method for correcting the “skew deviation” described above will be described with reference to FIGS. 7 and 8.
FIG. 7 shows an example of a functional configuration and image processing used for correcting skew deviation.
As shown in FIG. 7A, the control device 52 has a parameter setting unit 102, converts the rotation angle of each LED array 90 from the temperature value output from each temperature sensor 68 described above, The conversion result is output to the image processing device 54 as a correction parameter, and the operation of each exposure device 62 is controlled based on corrected image data described later.

  The image processing device 54 includes a correction processing unit 104, and data input from an image reading device (not shown) or an image input from a personal computer (not shown) or the like via a network line such as a LAN. Based on the correction parameters output from the control device 52 for the data (original image data), the position information of the original image data of each color is converted to perform image correction processing, and the corrected image data is output to the control device 52. It is supposed to be. Specifically, as shown in FIG. 7B, the image processing device 54 performs position correction processing on the original image data (left side of FIG. 7B), specifically, each LED array 90. A skew correction process for correcting the skew deviation is performed, and corrected image data (on the right side of FIG. 8B) is output to the control device 52.

FIG. 8 is a flowchart for explaining the skew deviation correction process (S10).
As shown in FIG. 8, in step S <b> 100, the control device 52 determines whether or not the temperature values input from the four temperature sensors 68 have been referred to, and if all four temperature sensors 68 have been referred to, the step is performed. The process proceeds to S125. In other cases, that is, when there is an unreferenced temperature sensor 68, the process proceeds to step S105.

  In step S105, the control device 52 refers to the temperature value output from the temperature sensor 68, converts the rotation angle of the LED array 90 corresponding to the temperature sensor 68, and uses the conversion result as a correction parameter. To 54.

  In step S110, the control device 52 determines whether or not the temperature value output from the temperature sensor 68 has changed. If there is a change, the process proceeds to step S120. If there is no change, step S100 is performed again. Move on to processing.

  In step S120, the image processing device 54 performs image data (original image data) input from an image reading device (not shown) or the like based on the correction parameter corresponding to the temperature sensor 68 referred to in step S105. Position correction (skew correction) processing is performed, and corrected image data is output to the control device 52.

  The control device 52 repeats the processing from step S100 to step S120 described above a predetermined number of times (in this example, four times), refers to the temperature values of all four temperature sensors 68, and changes to the temperature value. Control is performed to perform position correction (skew correction) processing on the original image data corresponding to (LED array 90).

  In step S125, the control device 52 controls the operation of each exposure device 62 based on the corrected image data. Thereby, the skew deviation due to the change in the angle of the LED array 90 with respect to the photoconductor 58 is suppressed.

  In step S130, the control device 52 clears the reference history of each temperature sensor 68, and proceeds to the process of step S100 again.

As described above, the magnification in the main scanning direction due to the thermal expansion of each LED array 90 is adjusted by adjusting the relative angle between the photoconductor 58 and the LED array 90 according to the length variation of the LED array 90 in the main scanning direction. The fluctuation can be suppressed, and the image quality in the output image can be maintained. Further, the angle of each LED array 90 of yellow (Y), magenta (M), cyan (C), and black (K) is adjusted according to the thermal expansion of each LED array 90, so Thus, even when there is a temperature difference (magnification variation difference) in each LED array 90, the image quality in the output image can be maintained.
Further, position correction processing is performed on the input image data based on the temperature value of the temperature sensor 68 corresponding to the LED array 90, and the operation of the exposure device 68 is controlled based on the corrected image data, that is, the main scanning direction of the LED array 90. By performing image processing on the image data in accordance with the variation in the length of the image, skew deviation caused by a change in the angle of the LED array 90 with respect to the photoconductor 58 can be suppressed.

Next, a modification of the above embodiment will be described with reference to FIGS.
FIG. 9 is a diagram illustrating a functional configuration used for correcting skew deviation and a write timing in each LED 88 in the present modification.

  As shown in FIG. 9A, the image processing device 54 has an image analysis unit 106, and is a personal computer (data input from an image reading device (not shown) or a network line such as a LAN). The area coverage (area ratio) and the like of the image data of each color input from an image (not shown) is analyzed, and the analysis result is output to the control device 52.

  The control unit 52 includes a light emission amount counting unit 108 and a timing control unit 110. The light emission amount counting unit 108 calculates the light emission amount of each LED array 90 based on the image analysis result output from the image processing device 54, and further cumulatively counts the light emission amount of each LED array 90. The result is output to the timing control unit 110. The timing control unit 110 controls the writing timing of each LED 88 of the LED array 90 to each photoconductor 58 based on the accumulated light emission value of each LED array 90 output from the light emission amount counting unit 108. More specifically, as shown in 10 (b), the control device 52 sensitizes each LED 88 of the LED array 90 to compensate for the skew deviation of the LED array 90 based on the accumulated light emission amount of each LED array 90. The writing timing on the body 58 is controlled so that the position of the irradiation light of the LED array 90 in the main scanning direction is the same as or parallel to the rotational axis direction of the photoreceptor 58.

FIG. 10 is a flowchart for explaining skew deviation correction processing (S20) in the present modification.
As shown in FIG. 10, in step S200, the image processing device 54 analyzes the area coverage (area ratio) of the image data of each color input from an image reading device (not shown) and the like, and the analysis results are analyzed. Output to the controller 52.

  In step S205, the control device 52 determines whether or not the light emission amounts of the LED arrays 90 in the four LED arrays 90 are referred to, and when the light emission amounts of all four LED arrays 90 are referred to, the control device 52 again. The process proceeds to step S200, and in other cases, that is, when there is an LED that does not refer to the light emission amount of the LED array 90, the process proceeds to step S210.

  In step S210, the control device 52 calculates the light emission amount of the LED array 90 based on the image analysis result output from the image processing device 54, and cumulatively counts the light emission amount of the LED array 90.

  In step S215, the control device 52 determines whether or not the value of the cumulative light emission amount of the LED array 90 is equal to or greater than a predetermined value, and if it is determined that the cumulative light emission amount of the LED array 90 has reached the predetermined value. The process proceeds to S220, and if it is determined that the predetermined value has not been reached, the process proceeds to Step S205 again.

  In step S <b> 220, the control device 52 sets the write timing to the photoconductor 58 in each LED 88 of the LED array 90 so that the skew deviation of the LED array 90 is canceled based on the value of the accumulated light emission amount of the LED array 90. Control.

  In step S225, the control device 52 clears the cumulative count value of the light emission amount of the LED array 90, and proceeds to the process of step S205 again.

  The control device 52 repeats the processing from step S205 to step S215 or step S205 to step S225 described above a predetermined number of times (in this example, four times), and cumulatively counts the light emission amounts of all four LED arrays 90, and the cumulative light emission. The writing timing of each LED 88 of each LED array 90 of yellow (Y), magenta (M), cyan (C), and black (K) to each photoconductor 58 is controlled by the amount value.

  As described above, in this modification, the input image data is analyzed, and each photoconductor 58 in each LED 88 of the LED array 90 is canceled so that the skew deviation is canceled based on the accumulated light emission amount of each LED array 90. Due to the change in the angle of the LED array 90 relative to the photoconductor 58 by controlling the write timing to the photoconductor 58, that is, by controlling the write timing in each of the plurality of LEDs according to the length variation of the LED array 90 in the main scanning direction. Skew deviation can be suppressed. Further, by calculating the length variation of the LED array 90 in the main scanning direction based on the light emission amount of the LED array 90, it is not necessary to provide a temperature sensor, and the apparatus can be made compact.

Next, a second embodiment will be described.
FIG. 11 shows an exposure apparatus 62 in the second embodiment.
The exposure apparatus 62 in this embodiment includes an exposure apparatus main body 82 in which the LED array 90 and the like are accommodated, and an adjustment unit 98. The adjusting means 98 includes a rotation shaft 112 provided in a direction parallel to the rotation axis direction of the photoconductor 58 and an actuator (not shown) that rotates the rotation shaft. The rotation shaft 112 connects the exposure apparatus main body 82 and the image forming unit main body 56 (not shown), and supports the exposure apparatus main body 82 in a freely rotatable manner. Therefore, the angle of the LED array 90 with respect to the photosensitive member 58 is changed by the adjusting means 98 around the rotation shaft 112 provided in a direction parallel to the rotational axis direction of the photosensitive member 58.

As shown in FIG. 11, the LED array 90 is pre-determined about a rotation shaft 112 provided in a direction parallel to the rotation axis direction of the photoconductor 58 according to the length variation of the LED array 90 in the main scanning direction. By rotating the angle (for example, turning the angle α in the direction of the arrow H1 or H2 in FIG. 11), fluctuations in magnification in the main scanning direction due to thermal expansion of the LED array 90 can be suppressed.
Note that when the LED array 90 is rotated around a rotation shaft 112 provided in a direction parallel to the axial direction of the photoconductor 58, the focal length with respect to the photoconductor 58 may shift. For example, a focus lens (see FIG. (Not shown) may be provided so as to be movable with respect to the LED array 90, and the deviation of the focal length may be corrected by adjusting the distance between the LED array 90 and the focus lens.

Next, a third embodiment will be described.
FIG. 12 shows an exposure apparatus 62 in the third embodiment.
The exposure apparatus 62 in this example includes an exposure apparatus main body 82 in which the LED array 90 and the like are accommodated, and an adjustment unit 98. The adjusting means 98 includes a rotating shaft 114 provided in a direction that is not on the same plane as the rotating shaft direction of the photoconductor 58, and an actuator (not shown) that rotates the rotating shaft 114. The rotation shaft 114 connects the exposure apparatus main body 82 and the image forming unit main body 56 (not shown), and supports the exposure apparatus main body 82 in a freely rotatable manner. Accordingly, the angle of the LED array 90 with respect to the photoconductor 58 is changed by the adjusting means 98 around the rotation shaft 114 provided in a direction not coplanar with the rotation axis direction of the photoconductor 58.

As shown in FIG. 12, the LED array 90 is centered on a rotating shaft 114 provided in a direction that is not on the same plane as the rotating shaft direction of the photoconductor 58 in accordance with the length variation of the LED array 90 in the main scanning direction. As shown in FIG. 12, the magnification variation in the main scanning direction of the LED array 90 can be suppressed.
Note that if the LED array 90 is rotated around a rotation shaft 114 provided in a direction that is not on the same plane as the axial direction of the photosensitive member 58, the focal length with respect to the photosensitive member 58 may be shifted. As in the first embodiment, for example, a focus lens (not shown) is provided so as to be movable with respect to the LED array 90, and the focal length deviation is corrected by adjusting the distance between the LED array 90 and the focus lens. May be.

  As described above, the present invention can be used for an exposure apparatus and an image forming apparatus provided with the exposure apparatus.

1 is a side view showing an image forming apparatus according to an embodiment of the present invention. It is a longitudinal cross-sectional view which shows the image formation means which concerns on embodiment of this invention. It is a longitudinal cross-sectional view which shows the exposure apparatus which concerns on embodiment of this invention. 1 shows an LED array according to an embodiment of the present invention, wherein (a) is a top view of an LED array having a rotation axis at an end, and (b) is a top view of an LED array having a rotation axis at the center in the main scanning direction. It is. It is a figure explaining the magnification fluctuation of the main scanning direction by the thermal expansion of the LED array which concerns on embodiment of this invention, (a) And (b) shows the main scanning magnification deviation by the thermal expansion of an LED array, (c). Indicates changes in the main scanning magnification deviation due to rotation of the LED array. It is a figure explaining operation | movement of the adjustment means which concerns on embodiment of this invention, (a) shows the state before thermal expansion of an LED array, (b) shows the state which the LED array thermally expanded, (c). Indicates a state in which the LED array is rotated. 2A and 2B are diagrams for explaining a skew deviation correction method in the control device according to the embodiment of the present invention, in which FIG. 1A is a block diagram illustrating a functional configuration used for skew deviation correction, and FIG. 2B is an image used for skew deviation correction; It is a schematic diagram explaining a correction process. It is a flowchart explaining the skew deviation correction process which concerns on embodiment of this invention. It is a figure explaining the correction method of the skew deviation which concerns on the modification of embodiment of this invention, (a) is a block diagram which shows the function structure used for skew deviation correction, (b) demonstrates the write-in timing in each LED. It is a schematic diagram to do. It is a flowchart explaining the skew deviation correction process which concerns on the modification of embodiment of this invention. It is a side view which shows the exposure apparatus and photoconductor which concern on the 2nd Embodiment of this invention. It is a front view which shows the exposure apparatus and photoconductor which concern on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming apparatus main body 52 Control apparatus 54 Image processing apparatus 58 Photoconductor 62 Exposure apparatus 88 LED
90 LED array 96 Rotating shaft 98 Adjustment means 100a, 100b Arm

Claims (9)

An exposure apparatus that writes a latent image by irradiating light to a photoconductor,
A light-emitting element array comprising a plurality of light-emitting elements arranged in alignment, and an adjusting means for adjusting a relative angle between the photoconductor and the light-emitting element array in accordance with a length variation in the main scanning direction of the light-emitting element array. An exposure apparatus comprising:   The exposure apparatus according to claim 1, wherein the light emitting element is an LED.   3. The adjustment unit according to claim 1, wherein the adjusting unit changes an angle of the light emitting element array with respect to the photosensitive member around a rotation axis provided in a direction perpendicular to the axial direction of the photosensitive member. Exposure device.   3. The adjustment unit according to claim 1, wherein the adjustment unit changes an angle of the light emitting element array with respect to the photosensitive member around a rotation shaft provided in a direction parallel to the axial direction of the photosensitive member. Exposure device.   The exposure apparatus according to claim 3, wherein the rotation shaft is disposed at at least one position near a center and an end portion in the main scanning direction of the light emitting element array.   6. The exposure apparatus according to claim 3, wherein the adjusting unit includes an arm member provided in the vicinity of at least one end of the light emitting element array. A photoreceptor,
An exposure device that irradiates the photosensitive member with light and writes a latent image;
Have
The exposure apparatus adjusts a relative angle between the light emitting element array composed of a plurality of light emitting elements arranged in alignment and a length of the light emitting element array in a main scanning direction in accordance with a change in length in the main scanning direction. And an adjustment unit.   The image forming apparatus according to claim 7, further comprising a control unit configured to control writing timing in the plurality of light emitting elements according to a length variation of the light emitting element array in a main scanning direction.   The image forming apparatus according to claim 8, further comprising an image processing unit configured to perform image processing on image data in accordance with a variation in length of the light emitting element array in a main scanning direction.

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