JP2007210154A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus detecting a deviation between a photosensitive body and an optical head without rotating the photosensitive body by a plurality of turns even in a main scanning direction or a sub-scanning direction. <P>SOLUTION: This image forming apparatus comprises the optical head which has a plurality of elements arranged in a longitudinal direction along a main scanning direction and is adapted to expose an image region and a prescribed area of a region out of the image region, the photosensitive body on which an image is formed by the movement in the sub-scanning direction perpendicular to the main scanning direction and exposure of the optical head, a photosensor having a plurality of elements provided on the face of the photosensitive body on predetermined positions at both ends of the region out of the image region in the main scanning direction of the photosensitive body, a control section for controlling to allow the optical head at the position corresponding to the photosensor to emit a light at a prescribed timing, and a deviation detection section for detecting a relative deviation between the optical head and the photosensitive body according to the detection result of the emission of the light of the optical head by means of the photosensor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  In the present invention, a plurality of elements are arranged in the longitudinal direction, the longitudinal direction is arranged along the main scanning direction, the movement in the sub-scanning direction orthogonal to the main scanning direction, and the exposure of the optical head. The present invention relates to an image forming apparatus having a photoconductor on which an image is formed, and to an image forming apparatus capable of detecting a deviation between an optical head and a photoconductor.

  In the image forming apparatus, two-dimensional image formation is performed by periodically repeating the act of scanning the photosensitive member or the recording paper in the main scanning direction while moving the photosensitive member or the recording paper in the sub-scanning direction. ing. In general, exposure in the main scanning direction corresponding to image data is performed from an optical head on a photosensitive member such as a charged photosensitive drum or a photosensitive belt rotating in the sub-scanning direction.

In such an image forming apparatus, as an optical head for performing exposure in the main scanning direction, there is an LED printer head composed of LEDs of a plurality of elements in the main scanning direction.
In this type of LED printer head, it is known that the position of the light emitting element is shifted as a result of deformation of each part due to heat generation or temperature change of the head itself. Also, the LED printer head may be displaced when the LED printer head is attached or when the image forming apparatus is installed.

For this reason, in this type of image forming apparatus, it has been proposed to provide a sensor for detecting the deviation between the LED printer head and the photosensitive member.
Regarding such an image forming apparatus, related techniques are described in Patent Document 1 and Patent Document 2 below.
JP-A-6-210899 (first page, FIG. 1) Japanese Patent Laid-Open No. 11-58815 (first page, FIG. 1)

  In Patent Document 1 described above, one sensor is provided at each of the front end and the end of the photoconductor in the main scanning direction, and the width between certain dots is detected and corrected. Thus, although it is possible to detect a deviation in the main scanning direction, there is a problem that the deviation detection in the sub-scanning direction is not considered.

  Further, in Patent Document 2 described above, it is possible to detect a shift between the main scanning direction and the sub-scanning direction by providing a light passage hole on the photosensitive member. However, in order to detect the LED element passing through the passage hole, it is necessary to sequentially turn on the LED element while rotating the photosensitive member, and as a result, a measurement time for a plurality of rotations of the photosensitive member is required. Have.

  The present invention has been made in order to solve the above-described problems, and the photosensitive member and the optical head can be used without rotating the photosensitive member a plurality of times in the main scanning direction or the sub-scanning direction. An object of the present invention is to provide an image forming apparatus capable of detecting a deviation from the above.

The present invention for solving the above problems is as described below.
(1) In the first aspect of the invention, light that exposes an image region and a predetermined range outside the image region in which a plurality of elements are arranged in the longitudinal direction and the longitudinal direction is arranged along the main scanning direction. A head, a photosensitive member on which an image is formed by movement in the sub-scanning direction orthogonal to the main scanning direction and exposure of the optical head, and an image on the photosensitive member surface in the main scanning direction of the photosensitive member. An optical sensor composed of a plurality of elements arranged at predetermined positions on both ends outside the area; a control unit that controls the optical head at a position corresponding to the optical sensor to emit light at a predetermined timing; and An image forming apparatus comprising: a shift detection unit configured to detect a relative shift between the optical head and the photosensitive member based on a detection result of light emission of the optical head.

  (2) The invention described in claim 2 is a light that exposes an image area and a predetermined range outside the image area, in which a plurality of elements are arranged in the longitudinal direction, and the longitudinal direction is arranged along the main scanning direction. A head, a photosensitive member on which an image is formed by movement in the sub-scanning direction orthogonal to the main scanning direction and exposure of the optical head, and an image on the photosensitive member surface in the main scanning direction of the photosensitive member. A slit disposed at a predetermined position at both ends outside the region and a predetermined portion at both ends outside the image region in the main scanning direction inside the photoconductor so as to receive light from the optical head that has passed through the slit. An optical sensor composed of a plurality of elements arranged in a fixed state; a control unit that controls the optical head at a position corresponding to the optical sensor to emit light at a predetermined timing; and the light from the optical sensor. Detection result of head emission More, an image forming apparatus characterized by having a deviation detector for detecting a relative displacement between the photosensitive member and the optical head.

  (3) The invention described in claim 3 is a light which exposes an image area and a predetermined range outside the image area, in which a plurality of elements are arranged in the longitudinal direction and the longitudinal direction is arranged along the main scanning direction. A head, a photosensitive member on which an image is formed by movement in the sub-scanning direction orthogonal to the main scanning direction and exposure of the optical head, and an image on the photosensitive member surface in the main scanning direction of the photosensitive member. Reflecting portions arranged at predetermined positions on both ends outside the region, and outside the photoconductor and outside the image region in the main scanning direction so as to receive light from the optical head reflected by the reflecting portion. An optical sensor composed of a plurality of elements arranged in a fixed state at both ends, a control unit for controlling the optical head at a position corresponding to the optical sensor to emit light at a predetermined timing, and the optical sensor In the light emission detection result of the optical head Ri is an image forming apparatus characterized by having a deviation detector for detecting a relative displacement between the photosensitive member and the optical head.

  (4) In the invention according to claim 4, the optical sensor is constituted by a plurality of elements at each of both ends, and the shift detector is in the main scanning direction according to the position of the element received by the optical sensor. The image forming apparatus according to claim 1, wherein the shift detection is performed.

  (5) The invention according to claim 5 is characterized in that the deviation detection unit detects the deviation in the sub-scanning direction based on a deviation of light reception timing between both ends of the optical sensor. Item 4. The image forming apparatus according to Item 3.

  (6) The invention according to claim 6 is characterized in that the optical head includes any one of an LED, an organic EL element, and a combination of a light source and shutter means. An image forming apparatus according to claim 5.

According to the present invention, the following effects can be obtained.
(1) In the image forming apparatus according to the first aspect of the present invention, an image is formed by exposing the photosensitive member moving in the sub-scanning direction from the optical head to the image area and a predetermined range outside the image area. In the forming apparatus, an optical head at a position corresponding to the optical sensor emits light at a predetermined timing with respect to an optical sensor arranged at a predetermined position on both ends outside the image area in the main scanning direction of the photoconductor. The shift detection unit detects a relative shift between the optical head and the photosensitive member based on the detection result of the light emission of the optical head by the optical sensor.

  That is, by referring to the detection results of the multi-element optical sensors at both ends of the photoconductor, the photoconductor without rotating the photoconductor a plurality of times in the main scanning direction or the sub-scanning direction. It is possible to detect a deviation between the optical head and the optical head.

  (2) In the invention of the image forming apparatus according to the second aspect, the image is formed by exposing the photosensitive member moving in the sub-scanning direction from the optical head to the image area and a predetermined range outside the image area. In the forming apparatus, with respect to the slits arranged at predetermined positions on both ends outside the image area in the main scanning direction of the photoreceptor, the optical head at the position corresponding to the slit is caused to emit light at a predetermined timing according to an instruction from the control unit, Based on the detection result of the light emission of the optical head that has passed through the slit detected by the optical sensor inside the photosensitive member, the shift detector detects the relative shift between the optical head and the photosensitive member.

  That is, with respect to the light transmitted through the slits at both ends of the photoconductor at both ends of the photoconductor, by referring to the detection results of the multi-element photosensors, both in the main scanning direction and in the sub-scanning direction. It is possible to detect the deviation between the photoconductor and the optical head without rotating the photoconductor a plurality of times.

  (3) In the invention of the image forming apparatus according to the third aspect, the image is formed by exposing the photosensitive member moving in the sub-scanning direction from the optical head to the image area and a predetermined range outside the image area. In the forming apparatus, an optical head at a position corresponding to the reflecting portion emits light at a predetermined timing according to an instruction from the control unit with respect to the reflecting units disposed at predetermined positions on both ends outside the image area in the main scanning direction of the photoconductor. The deviation detection unit detects a relative deviation between the optical head and the photosensitive member based on the detection result of the light emission of the optical head reflected by the reflection unit and detected by the external optical sensor.

  In other words, by referring to the detection results of the multi-element photosensors for the light reflected by the reflection portions at both ends of the photoconductor at each of the both ends of the photoconductor, the subscanning direction is maintained even in the main scanning direction. However, it is possible to detect the deviation between the photoconductor and the optical head without rotating the photoconductor a plurality of times.

  (4) In the invention of the image forming apparatus according to the fourth aspect, in the above (1) to (3), the shift detection in the main scanning direction is performed according to the position of the received element in the multi-element optical sensor.

  That is, with respect to the light received, transmitted, or reflected at both ends of the photoconductor, by referring to the light receiving position of the multi-element photosensor, the photoconductor and the optical head can be rotated without rotating the photoconductor multiple times. A shift in the main scanning direction can be detected.

  (5) In the invention of the image forming apparatus according to the fifth aspect, the shift detection unit detects a shift in the sub-scanning direction based on a shift in light reception timing between both ends of the optical sensor. An image forming apparatus according to claim 3.

  That is, with respect to the light received, transmitted or reflected at both ends of the photosensitive member, the sub-scanning of the photosensitive member and the optical head can be performed without rotating the photosensitive member a plurality of times by referring to the difference in light reception timing of the optical sensor. It becomes possible to detect a deviation in direction.

  (6) In the invention of the image forming apparatus according to the sixth aspect, in the above (1) to (5), from the optical head including any combination of the LED, the organic EL element, the light source and the shutter means to both ends of the photoconductor By referring to the light reception timing difference of the optical sensor for the light that is emitted toward each of the light received, transmitted, or reflected, the main body of the photoconductor and the optical head can be rotated without rotating the photoconductor multiple times. It is possible to detect a deviation in the scanning direction and the sub-scanning direction.

  The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described below in detail with reference to the drawings. Hereinafter, the configuration and operation of the image forming apparatus will be described. However, the operation of the image forming apparatus is an image forming method.

<Electrical configuration of image forming apparatus>
FIG. 1 is a circuit configuration diagram showing a configuration of main electrical components of the image forming apparatus 100 according to the first embodiment of the present invention.

  In FIG. 1, a control unit 101 is a unit that controls each unit of the image forming apparatus 100, and includes an operation input unit 102, a display unit 103, an image processing unit 120, a light emission drive unit 140, a rotation drive unit 160, and a deviation detection unit 190. Etc. are connected. The control unit 101 performs control for causing the optical head 150 at a position corresponding to an optical sensor 180 described later to emit light at a predetermined timing.

  The operation input unit 102 receives an operation input from a user or a key operator for setting operation of the image forming apparatus 100, and an output is connected to the control unit 101. A display unit 103 is a unit that displays various states of the image forming apparatus 100 to the user, and an input is connected to the control unit 101. Here, although the operation input unit 102 and the display unit 103 that individually perform input and display of operations are shown, the configuration of an operation display unit that includes a touch panel that performs both may be used.

  The print controller 105 is a unit that performs control when image data is exchanged with an external device (not shown), and an output is connected to an input terminal of the image processing unit 120. The image reading unit 110 optically scans and reads image information of a document to generate image data, and an output is connected to an input terminal of the image processing unit 120.

  The image processing unit 120 executes various types of image processing for image formation. A print controller 105 and an image reading unit 110 are connected to the input, and a light emission driving unit 140 is connected to the output. An image storage unit 130 is connected to the input / output.

The light emission drive unit 140 is a unit that generates a light emission drive signal according to image data. The image processing unit 120 is connected to the input, and the optical head 150 is connected to the output.
The optical head 150 has a plurality of elements arranged in the longitudinal direction, the longitudinal direction is arranged along the main scanning direction, and the light emission driving unit 140 is connected to the image area of the photoreceptor 170 and a predetermined range outside the image area. And means for performing exposure.

The rotation driving unit 160 is means for rotating the photosensitive member 170 in the sub-scanning direction, and an input is connected to the control unit 101.
The photosensitive member 170 is configured in a belt shape or a cylindrical shape, and exposure in the main scanning direction is periodically performed by the optical head 150 in a state where the photosensitive member 170 is rotationally driven in the sub-scanning direction by the rotation driving unit 160, thereby generating a two-dimensional image. An image carrier to be formed.

The optical sensor 180 is a means for detecting light by arranging a plurality of elements at predetermined positions on both ends outside the image area in the main scanning direction of the photoreceptor 170.
As shown in FIG. 2A, the optical sensor 180 can be arranged on the surface of the photosensitive member 170 like 180L and 180R. In that case, the detection output of the optical sensor 180 is output to the outside from the photoreceptor 170 via means such as a slip ring.

  Further, as shown in FIG. 2B, the optical sensor 180 has 180 L ′ inside the photoconductor 170 so as to receive light through the slit 170SL and the slit 170SR formed on the surface of the photoconductor 170. It can be arranged in a fixed state such as 180R ′ (not shown).

  In addition, as shown in FIG. 2C, the optical sensor 180 receives 180L "outside the photosensitive member 170 so as to receive reflected light from the mirror 170ML and the mirror 170MR formed on the surface of the photosensitive member 170. And 180R "can be arranged in a fixed state.

  The deviation detection unit 190 is a means for detecting a deviation between the optical head 150 and the photosensitive member 170, the detection output of the optical sensor 180 is connected to the input, and the output is connected to the control unit 101.

Since various known configurations can be used as the mechanical configuration of the image forming apparatus 100 used in the present embodiment, description of the mechanical configuration is omitted.
<Operation of Image Forming Apparatus (1)>
Hereinafter, the operation of the image forming apparatus according to the first embodiment will be described.

  Here, as a relation between the optical head 150 and the optical sensor 180, as shown in FIG. 3A, S1 to S4 are provided around the surface of the photosensitive member that receives light from the light emitting element at the left end of the optical head 150. An optical sensor 180L having four light receiving elements is arranged. Similarly, as shown in FIG. 3A, an optical sensor 180L of four light receiving elements S5 to S8 is arranged around the surface of the photosensitive member that receives light from the light emitting element at the right end of the optical head 150. . Here, it is desirable to determine the light receiving range and the number of light receiving elements so that light can be received by any one of the light receiving elements even when the light emitting position or the light receiving position is displaced due to deformation due to deformation or heat generation.

Here, at the start of use of the image forming apparatus 100 or immediately after the replacement of the photosensitive member 170, the control unit 101 performs the following deviation detection.
First, when the optical head 150 includes a plurality of light emitting elements such as LEDs, the control unit 101 causes the light emitting elements at both ends to emit light. Further, when the optical head 150 includes a light source and a plurality of shutter means, the control unit 101 opens the shutters corresponding to the pixels at both ends to emit light at both ends.

  At this time, as a result of light reception by the optical sensor 180, that is, which light receiving element receives light is input to the deviation detection unit 190. Here, the deviation detecting unit 190 detects the deviation state by comparing with a predetermined appropriate light receiving state, and notifies the control unit 101 of the detection result of the deviation state.

  Here, when the optical head 150 and the photoconductor 170 are properly arranged in the main scanning direction without deviation, light from both ends of the optical head 150 is detected by the S2 element and the S7 element of the optical sensor 180. It is assumed that it is possible (FIG. 3 (b) normal value).

  For example, when light is received at the light receiving elements S2 and S6 (second stage in FIG. 3B), the left end of the optical head 150 is normal, but the right side is contracted. It is detected that there is.

  Further, for example, when light is received by the light receiving elements S1 and S6 (the third stage in FIG. 3B), the left and right sides of the optical head 150 are equally shifted leftward. Detected as abnormal.

  In this way, with respect to the light received at both ends of the photoreceptor 170, the photoreceptor 170 and the optical head can be referred to without rotating the photoreceptor a plurality of times by referring to the light receiving positions of the multi-element optical sensor 180. It is possible to detect a deviation from 150 in the main scanning direction.

  Here, when the optical head 150 and the photosensitive member 170 are properly arranged in the sub-scanning direction without deviation or inclination, the S2 element and the S7 element of the optical sensor 180 are separated from both ends of the optical head 150. Can be detected with a time difference t (FIG. 3 (c) normal value). The time difference t is determined by the lighting time difference in the optical head 150 and the sub-scanning speed.

  For example, when light is received at a time difference t1 between the light receiving elements S2 and S7 (FIG. 3 (c), second stage), t1> t, and the optical head 150 is tilted upward to the right. It is detected that there is.

  For example, when light is received at a time difference t2 between the light receiving elements S2 and S7 (FIG. 3 (c), third stage), t2 <t and the optical head 150 is tilted downward. Detected as abnormal.

  Further, for example, when light is received with a time difference t2 ′ (−t2) between the light receiving elements S2 and S7 (FIG. 3 (c), the fourth stage), t2 <t, and the optical head 150 further moves to the right. It is detected as an abnormality in a state of leaning downward.

  In this way, with respect to the light received at both ends of the photoconductor 170, by referring to the light reception timing difference of the multi-element optical sensor 180, the photoconductor 170 and the light are rotated without rotating the photoconductor a plurality of times. Deviation in the sub-scanning direction from the head 150 (tilt in the sub-scanning direction) can be detected.

  Actually, there may be a case where the deviation in the main scanning direction and the inclination in the sub-scanning direction are combined, but in this case also, the deviation component in the main scanning direction and the inclination component in the sub-scanning direction are detected. It is also possible to detect separately.

<Operation of Image Forming Apparatus (2)>
The operation of the image forming apparatus according to the second embodiment will be described below.
Here, as shown in FIG. 4A, the relationship between the optical head 150 and the optical sensor 180 is fixed inside the photoreceptor 170 in order to receive light from the light emitting element at the left end of the optical head 150. The optical sensor 180L ′ arranged in a state and a slit 170SL is provided at the end of the photosensitive member 170 so as to transmit light to the optical sensor 180L ′. Similarly, as shown in FIG. 4A, in order to receive light from the light emitting element at the right end of the optical head 150, an optical sensor 180R ′ disposed in a fixed state inside the photosensitive member 170, and this A slit 170SR is provided at the end of the photoconductor 170 so as to transmit light to the optical sensor 180R ′.

  It should be noted that the light receiving range (slit range, light receiving element range) and the light receiving element so that light can be received by any of the light receiving elements even when the light emitting position or the light receiving position is shifted due to deformation due to heat generation or attachment. It is desirable to determine the number.

Here, at the start of use of the image forming apparatus 100 or immediately after the replacement of the photosensitive member 170, the control unit 101 performs the following deviation detection.
First, when the optical head 150 includes a plurality of light emitting elements such as LEDs, the control unit 101 causes the light emitting elements at both ends to emit light. Further, when the optical head 150 includes a light source and a plurality of shutter means, the control unit 101 opens the shutters corresponding to the pixels at both ends to emit light at both ends.

  At this time, as a result of light reception by the optical sensor 180, that is, which light receiving element receives light is input to the deviation detection unit 190. Here, the deviation detecting unit 190 detects the deviation state by comparing with a predetermined appropriate light receiving state, and notifies the control unit 101 of the detection result of the deviation state.

  Here, when the optical head 150 and the photosensitive member 170 are properly arranged in the main scanning direction without deviation, both ends of the optical head 150 are connected by the S2 element and the S7 element of the optical sensor 180 through the slit 170SL. It is assumed that light from the part can be detected (FIG. 4 (b) normal value).

  For example, when light is received at the light receiving elements S2 and S6 (second stage in FIG. 4B), the left end of the optical head 150 is normal but the right side is contracted. It is detected that there is.

  Further, for example, when light is received by the light receiving elements S1 and S6 (third stage in FIG. 4B), the left and right sides of the optical head 150 are equally shifted leftward. Detected as abnormal.

  As described above, the light received through the slits at each of both ends of the photosensitive member 170 is referred to the light receiving position of the multi-element optical sensor 180, so that the photosensitive member is not rotated a plurality of times. It is possible to detect a deviation in the main scanning direction between the body 170 and the optical head 150.

  Here, when the optical head 150 and the photosensitive member 170 are properly arranged in the sub-scanning direction without any deviation or inclination, the optical head 150 is configured by the S2 element and the S7 element of the optical sensor 180 through the slit. It is assumed that the light from both ends of can be detected with a time difference t (FIG. 4 (c) normal value). The time difference t is determined by the lighting time difference in the optical head 150 and the sub-scanning speed.

  For example, when light is received at a time difference t1 between the light receiving elements S2 and S7 (FIG. 4 (c), second stage), t1> t and the optical head 150 is tilted upward to the right. It is detected that there is.

  For example, when light is received at a time difference t2 between the light receiving elements S2 and S7 (FIG. 4 (c), third stage), t2 <t and the optical head 150 is tilted to the right. Detected as abnormal.

  Furthermore, for example, when light is received at a time difference t2 ′ (−t2) between the light receiving elements S2 and S7 (FIG. 4C, the fourth stage), t2 <t and the optical head 150 is further moved to the right. It is detected as an abnormality in a state of leaning downward.

  In this way, with respect to the light received by the photosensor 180 inside the photoconductor through the slits at both ends of the photoconductor 170, the photoconductor is changed by referring to the light reception timing difference of the multi-element photosensor 180. It is possible to detect a shift in the sub-scanning direction (tilt in the sub-scanning direction) between the photosensitive member 170 and the optical head 150 without rotating a plurality of times.

  Actually, there may be a case where the deviation in the main scanning direction and the inclination in the sub-scanning direction are combined, but in this case also, the deviation component in the main scanning direction and the inclination component in the sub-scanning direction are detected. It is also possible to detect separately.

<Operation of Image Forming Apparatus (3)>
The operation of the image forming apparatus according to the third embodiment will be described below.
Here, as shown in FIG. 5A, the relationship between the optical head 150 and the optical sensor 180 is fixed outside the photoreceptor 170 in order to receive light from the light emitting element at the left end of the optical head 150. An optical sensor 180L ″ arranged in a state, and a mirror 170ML is provided at the end of the photosensitive member 170 so as to reflect light to the optical sensor 180L ″. Similarly, as shown in FIG. 5A, in order to receive light from the light emitting element at the right end of the optical head 150, an optical sensor 180R ″ arranged in a fixed state outside the photosensitive member 170, and this A mirror 170MR is provided at the end of the photoreceptor 170 so as to reflect the light to the optical sensor 180R ″.

  It should be noted that the light receiving range (mirror range, light receiving element range) or light receiving element is used here so that any light receiving element can receive light even if the light emitting position or light receiving position is displaced due to deformation due to heat generation or due to heat generation. It is desirable to determine the number.

Here, at the start of use of the image forming apparatus 100 or immediately after the replacement of the photosensitive member 170, the control unit 101 performs the following deviation detection.
First, when the optical head 150 includes a plurality of light emitting elements such as LEDs, the control unit 101 causes the light emitting elements at both ends to emit light. Further, when the optical head 150 includes a light source and a plurality of shutter means, the control unit 101 opens the shutters corresponding to the pixels at both ends to emit light at both ends.

  At this time, as a result of light reception by the optical sensor 180, that is, which light receiving element receives light is input to the deviation detection unit 190. Here, the deviation detecting unit 190 detects the deviation state by comparing with a predetermined appropriate light receiving state, and notifies the control unit 101 of the detection result of the deviation state.

  Here, when the optical head 150 and the photosensitive member 170 are properly arranged in the main scanning direction without deviation, both ends of the optical head 150 are connected by the S2 element and the S7 element of the optical sensor 180 via the mirror 170ML. It is assumed that the light from the part can be detected (FIG. 5 (b) normal value).

  For example, when light is received by the light receiving elements S2 and S6 (second stage in FIG. 5B), the left end of the optical head 150 is normal, but the right side is contracted. It is detected that there is.

  Further, for example, when light is received by the light receiving elements S1 and S6 (third stage in FIG. 5B), the left and right sides of the optical head 150 are equally shifted to the left. Detected as abnormal.

  As described above, with respect to the light received through the mirrors at both ends of the photosensitive member 170, the light receiving position of the multi-element optical sensor 180 is referred to, so that the photosensitive member is not rotated a plurality of times. It is possible to detect a deviation in the main scanning direction between the body 170 and the optical head 150.

  Here, when the optical head 150 and the photosensitive member 170 are properly arranged in the sub-scanning direction without deviation or inclination, the optical head 150 is composed of the S2 element and the S7 element of the optical sensor 180 via a mirror. It is assumed that the light from both ends of can be detected with a time difference t (FIG. 5 (c) normal value). The time difference t is determined by the lighting time difference in the optical head 150 and the sub-scanning speed.

  For example, when light is received at a time difference t1 between the light receiving elements S2 and S7 (FIG. 5 (c), second stage), t1> t and the optical head 150 is tilted upward to the right. It is detected that there is.

  Further, for example, when light is received at a time difference t2 between the light receiving elements S2 and S7 (FIG. 5 (c), third stage), t2 <t and the optical head 150 is tilted downward. Detected as abnormal.

  Further, for example, when light is received with a time difference t2 ″ (−t2) between the light receiving elements S2 and S7 (FIG. 5 (c), fourth stage), t2 <t, and the optical head 150 further moves to the right. It is detected as an abnormality in a state of leaning downward.

  As described above, with respect to the light received by the photosensor 180 outside the photoconductor through the mirrors at both ends of the photoconductor 170, the photoconductor is changed by referring to the light reception timing difference of the multi-element photosensor 180. It is possible to detect a shift in the sub-scanning direction (tilt in the sub-scanning direction) between the photosensitive member 170 and the optical head 150 without rotating a plurality of times.

  Actually, there may be a case where the deviation in the main scanning direction and the inclination in the sub-scanning direction are combined, but in this case also, the deviation component in the main scanning direction and the inclination component in the sub-scanning direction are detected. It is also possible to detect separately.

<Other embodiments>
The above-described deviation detection is preferably performed at the start of use of the image forming apparatus 100 or at a periodic diagnosis, and is preferably performed when the photosensitive member is replaced, because it is possible to detect the deviation of the newly installed photosensitive member.

1 is a circuit configuration diagram showing an electrical configuration of an image forming apparatus according to an embodiment of the present invention. It is explanatory drawing which shows the example of arrangement | positioning of the optical head of the embodiment of this invention, a photoreceptor, and an optical sensor. It is explanatory drawing which shows the operation state of 1st Embodiment of this invention. It is explanatory drawing which shows the operation state of 2nd Embodiment of this invention. It is explanatory drawing which shows the operation state of 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 101 Control part 102 Operation input part 103 Display part 105 Print controller 110 Image reading part 120 Image processing part 130 Image machine part 140 Light emission drive part 150 Optical head 160 Rotation drive part 170 Photoconductor 180 Optical sensor 190 Deviation detection Part

Claims (6)

An optical head that exposes an image area and a predetermined range outside the image area, in which a plurality of elements are arranged in the longitudinal direction, and the longitudinal direction is arranged along the main scanning direction;
A photoreceptor on which an image is formed by movement in a sub-scanning direction orthogonal to the main scanning direction and exposure of the optical head;
An optical sensor comprising a plurality of elements disposed at predetermined positions on both sides of the photoconductor surface and outside the image area in the main scanning direction of the photoconductor;
A control unit that performs control to cause the optical head at a position corresponding to the optical sensor to emit light at a predetermined timing;
A displacement detection unit that detects a relative displacement between the optical head and the photosensitive member based on a detection result of light emission of the optical head by the optical sensor;
An image forming apparatus comprising: An optical head that exposes an image area and a predetermined range outside the image area, in which a plurality of elements are arranged in the longitudinal direction, and the longitudinal direction is arranged along the main scanning direction;
A photoreceptor on which an image is formed by movement in a sub-scanning direction orthogonal to the main scanning direction and exposure of the optical head;
Slits disposed on the photoreceptor surface at predetermined positions on both ends outside the image area in the main scanning direction of the photoreceptor,
It is composed of a plurality of elements arranged in a fixed state at predetermined positions inside the photoconductor and outside the image area in the main scanning direction so as to receive light from the optical head that has passed through the slit. An optical sensor;
A control unit that performs control to cause the optical head at a position corresponding to the optical sensor to emit light at a predetermined timing;
A displacement detection unit that detects a relative displacement between the optical head and the photosensitive member based on a detection result of light emission of the optical head by the optical sensor;
An image forming apparatus comprising: An optical head that exposes an image area and a predetermined range outside the image area, in which a plurality of elements are arranged in the longitudinal direction, and the longitudinal direction is arranged along the main scanning direction;
A photoreceptor on which an image is formed by movement in a sub-scanning direction orthogonal to the main scanning direction and exposure of the optical head;
Reflectors disposed on the photoconductor surface at predetermined positions on both ends outside the image area in the main scanning direction of the photoconductor,
A plurality of elements arranged in a fixed state outside the photoconductor and at both ends outside the image area in the main scanning direction so as to receive the light from the optical head reflected by the reflecting portion. An optical sensor comprising:
A control unit that performs control to cause the optical head at a position corresponding to the optical sensor to emit light at a predetermined timing;
A displacement detection unit that detects a relative displacement between the optical head and the photosensitive member based on a detection result of light emission of the optical head by the optical sensor;
An image forming apparatus comprising: The photosensor is composed of a plurality of elements at each end.
The deviation detection unit performs the deviation detection in the main scanning direction according to the position of the element received by the optical sensor.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The shift detection unit performs the shift detection in the sub-scanning direction due to a shift in light reception timing between both ends of the optical sensor.
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The optical head is configured to include any of an LED, an organic EL element, a combination of a light source and shutter means,
The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.