JP5045075B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and in particular, controls the rotation speed of a rotating body by measuring the rotation of a rotating body such as a photosensitive drum or an intermediate transfer body by an encoder. In the image forming apparatus configured as described above, a rotating wheel provided with a large number of slits that rotate with the rotating body is inserted into a reading gap of the sensor that detects the slit, and the rotation of the rotating body, for example, In measuring the rotational speed, rotational acceleration, rotational position, etc., the present invention is characterized in that it prevents foreign matters such as grease from adhering to the slits provided in the rotating wheel.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, the rotational speed of a rotating body that is rotationally driven, such as a photosensitive drum or an intermediate transfer body, is measured by an encoder to control the rotational speed of the rotating body. Has been done.

  When the rotational speed of the rotating body is measured by the encoder as described above, a rotating wheel having a large number of slits is provided so as to rotate along with the rotating body, and the rotating wheel is used for sensor reading. The sensor is attached so as to be inserted into the gap, and the movement of the slit due to the rotation of the rotating wheel is read by the sensor (see, for example, Patent Document 1).

  Here, the above rotating wheel is generally attached to the same rotating shaft as the rotating gear for rotating the rotating body, and grease is applied to the rotating gear in order to improve the driving of the rotating gear. To be done.

However, when grease or the like is applied to the rotating gear as described above, there has been a problem that the grease or the like thus applied adheres to the slits of the rotating wheel and reading by the sensor cannot be performed properly.
JP 2003-247858 A

  The present invention provides an image forming apparatus provided with an encoder for measuring rotation of a rotating body, for example, rotational speed, rotational acceleration, rotational position, etc., and a rotating wheel provided with a number of slits that rotate with the rotating body. It is an object of the present invention to solve the above-mentioned problems when measuring the rotation of the rotating body by inserting it into the reading gap of the sensor for detecting the slit of the slit provided in the rotating wheel. It is an object of the present invention to prevent foreign matters such as grease from adhering to the surface, and to make it possible to stably and appropriately read the slit by the above-described sensor.

In the first image forming apparatus of the present invention, in order to solve the above-described problems, a reading wheel of a sensor that detects the slits on a rotating wheel provided with a large number of slits that rotate with a rotating body. In the image forming apparatus including the encoder that measures the rotation of the rotating body, the rotating wheel is attached to the same rotating shaft as the rotating gear that rotationally drives the rotating body, and the outer peripheral side of the rotating wheel The rotating gear is provided with a shielding member that shields at least a part of the rotating gear .
In the second image forming apparatus of the present invention, the rotation wheel provided with a number of slits that rotate with the rotating body is inserted into the reading gap of the sensor that detects the slits, and the rotation is performed. In an image forming apparatus including an encoder for measuring body rotation, a shielding member is provided to shield at least a part of the outer peripheral side of the rotating wheel, and the sensor is mounted on a sensor mounting plate. The sensor substrate was extended outside as long as it did not collide with the shielding member.

  In the image forming apparatus of the present invention, a start position detection sensor for detecting the rotation start position of the rotating wheel can be provided.

In the second image forming apparatus of the present invention, when the rotating wheel is attached to the same rotating shaft as the rotating gear for driving the rotating body to rotate, the shielding member is provided on the rotating gear. Can do.

  In the image forming apparatus of the present invention, the shielding member can be formed in an annular shape with a part cut away so as to surround the outer peripheral side of the rotating wheel. When the shielding member is formed in an annular shape with a part cut away, the cut position can be detected by the start position detection sensor as the rotation start position of the rotating wheel.

In the first image forming apparatus of the present invention, when the sensor for detecting the slit of the rotating wheel is provided, the sensor is mounted on the sensor mounting plate, and the sensor substrate is placed on the outside of the sensor. It is preferable to extend within a range that does not collide with.

  Further, in the image forming apparatus of the present invention, when a plurality of photosensitive drums are provided as the above-described rotating body and a photosensitive drum having an outer diameter different from that of the other photosensitive drums exists, the outer diameter is different from that of other photosensitive drums. The encoder is provided for a photosensitive drum different from the photosensitive drum.

  In the image forming apparatus according to the present invention, a rotating wheel provided with a large number of slits that rotate with the rotating body is inserted into a reading gap of a sensor that detects the slit, and the rotation of the rotating body, for example, In measuring the rotational speed, rotational acceleration, rotational position, etc., since a shielding member that shields at least part of the outer peripheral side of the rotating wheel is provided, even if grease applied to the rotating gear is scattered, the above It is possible to prevent grease and the like from being shielded by the shielding member and adhere to the slit of the rotating wheel, and the slit reading by the sensor can be stably and appropriately performed.

  Further, in the image forming apparatus provided with a plurality of photosensitive drums as the rotating body, when there is a photosensitive drum having an outer diameter different from that of the other photosensitive drums, Errors such as rotation unevenness that differ from other photoconductor drums with the same outer diameter occur, and when full-color image formation is performed using these photoconductor drums, there is a shift in the formed image. As in the image forming apparatus shown in the invention, the encoder is provided as described above for the photosensitive drums having different outer diameters, and the rotation of the photosensitive drums having different outer diameters is measured, and the photosensitive drums having different outer diameters are measured. By controlling the rotation speed of the image, the image shift as described above is suppressed, and a good full-color image can be obtained.

  Next, an image forming apparatus according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. The image forming apparatus according to the present invention is not limited to the one shown in the following embodiment, and can be implemented with appropriate modifications within a range not changing the gist thereof.

  In the image forming apparatus according to this embodiment, as shown in FIG. 1, an image reading apparatus 2 that reads an image is provided on the upper part of the apparatus main body 1, and four imaging units 10 </ b> A to 10 </ b> D are provided in the apparatus main body 1. It is attached detachably.

  In each of the imaging units 10A to 10D, the photosensitive drums 11A to 11D, the charging devices 12A to 12D for charging the surfaces of the photosensitive drums 11A to 11D, and the surfaces of the photosensitive drums 11A to 11D, respectively. Developing devices 13A to 13D are provided that supply toner to the formed electrostatic latent image to form a toner image.

  Each of the developing devices 13A to 13D in each of the imaging units 10A to 10D stores toner, and in this embodiment, yellow toner is added to the developing device 13A of the first imaging unit 10A. The magenta toner is used for the developing device 13B of the second imaging unit 10B, the cyan toner is used for the developing device 13C of the third imaging unit 10C, and the black toner is used for the developing device 13D of the fourth imaging unit 10D. I have to.

  In this embodiment, the outer diameter of the photosensitive drum 11D in the fourth imaging unit 10D using the black toner that is frequently used is the outer diameter of the photosensitive drums 11A to 11C in the other imaging units 10A to 10C. Is bigger than.

  Further, four toner cartridges 20A to 20D containing toner to be supplied to the developing devices 13A to 13D of the imaging units 10A to 10D corresponding to the four imaging units 10A to 10D are provided in the apparatus main body 1. It is designed to be detachably attached to the camera.

  In the image forming apparatus according to this embodiment, when full-color image formation is performed, the photosensitive drums 11A to 11D in the imaging units 10A to 10D are rotated, and the photosensitive drums 11A to 11D are rotated. The surfaces are charged by the charging devices 12A to 12D, and electrostatic latent images corresponding to the image information are formed by the latent image forming device 14 on the surfaces of the photosensitive drums 11A to 11D thus charged, respectively. The toner of each color is supplied from the developing devices 13A to 13D provided in the imaging units 10A to 10D to the surfaces of the photosensitive drums 11A to 11D on which the electrostatic latent images are formed. The toner images of the respective colors are formed on the surfaces 11A to 11D.

  Then, the toner images of the respective colors formed on the surfaces of the photosensitive drums 11A to 11D in the imaging units 10A to 10D in this way are sequentially transferred to the intermediate transfer belt 3 that is rotationally driven by the driving roller 3a. Thus, a full-color toner image is formed on the intermediate transfer belt 3.

  On the other hand, the recording medium S fed from the paper cartridge 4 is guided between the intermediate transfer belt 3 and the transfer roller 6 by the timing roller 5 at an appropriate timing, and the recording medium S formed on the intermediate transfer belt 3 is guided. The full-color toner image is transferred to the recording medium S. The full-color toner image transferred in this way is fixed on the recording medium S by the fixing device 7, and then the recording medium S is discharged.

  Here, in the image forming apparatus according to this embodiment, an encoder is provided for the photosensitive drum 11D in the fourth imaging unit 10D using black toner.

The encoder measures the rotational speed of the photosensitive drum 11D, and based on the result, the control means (not shown) controls the rotational speed of the photosensitive drum 11D to produce a full-color image. In the case of forming, the image shift is suppressed so that a good full-color image can be obtained.

  In the image forming apparatus according to this embodiment, the encoder is provided only for the photosensitive drum 11D in the fourth imaging unit 10D using black toner as described above. An encoder is also provided for the driving roller 3a for rotationally driving the photosensitive drums 11A to 11C and the intermediate transfer belt 3, and the rotational speed, rotational acceleration, rotational position, and the like thereof are measured, and control is performed based on the results. It is also possible to control the rotational speed and the like by means.

  Next, when measuring the rotation of the rotating body composed of the photosensitive drums 11A to 11D and the driving roller 3a of the intermediate transfer belt 3 as described above, a rotating wheel provided with a number of slits that rotate with the rotating body. The case where the encoder 30 is provided in such a manner that 31 is inserted into the reading gap 32a of the sensor 32 that detects the slit will be specifically described.

  Here, in this embodiment, as shown in FIG. 2, a large number of slits (not shown) are provided on the rotating shaft 42 to which the rotating gear 41 rotating with the rotating body as described above is attached. The rotating wheel 31 is attached to a predetermined position via a spacer 43 between the rotating gear 41 and the surface of the rotating gear 41 on the rotating wheel 31 side so as to surround the outer peripheral side of the rotating wheel 31. A shielding member 44 having an annular shape with a part cut away is provided.

  Then, as shown in FIGS. 3A and 3B, the rotating shaft 42 is rotatably held by a bearing portion 51 provided on the mounting plate 50, and the sensor 32 is mounted on the mounting plate 50. A pair of guide grooves 52 for sliding and guiding the sensor mounting plate 60 are provided, and a confirmation hole 53 for checking the mounting position of the sensor mounting plate 60 is provided in the vicinity of the bearing portion 51.

  Further, in the sensor mounting plate 60, as shown in FIGS. 4A and 4B, a pair of sensors 32 are attached to the lower surface of the sensor mounting plate 60 with a reading gap 32a facing each other through a required interval. The sensor board 33 is installed on the outside of each sensor 32. When the sensor mounting plate 60 is mounted on the mounting plate 50, each sensor board 33 is mounted on the rotating wheel 31. The surface of each sensor substrate 33 extends in a direction substantially orthogonal to the radial direction of rotation so as to shield the outside of each sensor 32 within a range where it does not collide with the projecting shielding member 44.

  And as the holding part 61 which hold | maintains so that the edge part of the outer side of each guide groove 52 of said mounting plate 50 may be pinched | interposed into the both sides of this sensor mounting plate 60, it may be bent upwards and extended in a hook shape. The outer surface holding portion 61a and the inner surface holding portion 61b extending from the sensor mounting plate 60 are provided, and the outer surface holding portion 61a is positioned on the outer surface side of the edge of the guide groove 52, and the inner surface holding portion is 61b is positioned on the inner surface side of the edge of the guide groove 52 so as to sandwich the edge of the guide groove 52.

  In addition, a positioning notch 62 is formed at the center of the sensor mounting plate 60 for positioning by contact with a bearing portion 51 provided on the mounting plate 50, and is opposite to the positioning notch 62. Is provided with a gripping portion 63 for gripping the sensor mounting plate 60, and a start position detection sensor 64 for detecting a notched end portion of the shielding member 44 provided on the rotary gear 41 on the lower surface of the gripping portion 63. Is provided.

  When attaching the sensor mounting plate 60 to the mounting plate 50 by inserting the rotating wheel 31 into the reading gap 32a of the sensor 32 as described above, as shown in FIG. The outer surface holding portion 61a in each holding portion 61 is positioned on the outer surface side of the outer edge of each guide groove 52 provided in the mounting plate 50, and the pair of sensors 32 and sensors provided in the sensor mounting plate 60 are provided. The rotating gear 41 is set so that the substrate 33 passes through the cutout portion of the shielding member 44, and in this state, the sensor mounting plate 60 is slid along the guide groove 52 provided in the mounting plate 50.

  In this way, the inner surface holding portion 61b of the sensor mounting plate 60 and each holding portion 61 is guided to the inner surface side of the mounting plate 50, and the inner surface side of the outer edge portion of the outer surface holding portion 61a and the guide groove 52 described above. The outer edge portion of each guide groove 52 is sandwiched by the inner surface holding portion 61 b guided to the sensor mounting plate 60, and the sensor mounting plate 60 is held by the mounting plate 50.

  In this state, the sensor mounting plate 60 is further slid along the guide groove 52 provided in the mounting plate 50, and as shown in FIGS. The positioning notch 62 provided is brought into contact with a bearing portion 51 provided on the mounting plate 50, and this is confirmed through a confirmation hole 53 provided on the sensor mounting plate 60, and from above the mounting plate 50. The sensor mounting plate 60 is attached to the mounting plate 50 with screws 45.

  In this way, the sensor mounting plate 60 is guided to an appropriate position along the guide groove 52 provided in the mounting plate 50, and the rotating wheel is inserted into the reading gap 32a of the sensor 32 mounted on the sensor mounting plate 60. The encoder 30 is appropriately set in a state in which 31 is properly inserted and the outer peripheral side of the rotating wheel 31 is surrounded by the shielding member 44.

  When the rotation speed of the rotating body is measured by the encoder 30 set as described above, the start position detection sensor 64 detects the notched end portion of the shielding member 44 as the rotation start position of the rotary wheel 31. Based on this position, the movement of the slit of the rotating wheel 31 is detected by the sensor 32, and the rotational speed of the rotating body is measured. If it does in this way, it will become possible to always measure what kind of rotation nonuniformity is in the rotation speed of a rotating body in a fixed state.

  Further, when the rotational speed of the rotating body is measured in this way, even when grease or the like is applied to the rotating gear 41, the outer peripheral side of the rotating wheel 31 is surrounded by the shielding member 44 as described above. Even if the grease applied to the rotating gear 41 is scattered by the sensor substrate 33 provided so as to shield the outside of each sensor 32, the scattered grease or the like is not covered by the shielding member. 44 and the sensor substrate 33 are prevented from adhering to the slit of the rotating wheel 31, and the slit of the rotating wheel 31 by the sensor 32 can be detected stably and appropriately.

1 is a schematic explanatory diagram of an image forming apparatus according to an embodiment of the present invention. In the image forming apparatus according to the above-described embodiment, it is a schematic perspective view showing a state in which a rotary wheel of an encoder is attached to a rotary shaft of a rotary gear provided with a shielding member. FIG. 5 is a schematic cross-sectional view and a schematic plan view showing a state in which a rotating wheel is rotatably provided on a mounting plate together with a rotating gear provided with a shielding member in the image forming apparatus according to the embodiment. FIG. 4 is a schematic cross-sectional view and a schematic plan view showing a state where an encoder sensor is mounted on a sensor mounting plate in the image forming apparatus according to the embodiment. FIG. 6 is a schematic plan view showing a state in which the sensor mounting plate is slid along a guide groove provided on the mounting plate in the image forming apparatus according to the embodiment. In the image forming apparatus according to the above-described embodiment, the sensor mounting plate is slid to a predetermined position along the guide groove provided on the mounting plate to be mounted on the mounting plate, and the rotating wheel is inserted into the sensor reading gap. It is the shown schematic sectional drawing and schematic plan view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Device main body 2 Image reading device 3 Intermediate transfer belt 3a Drive roller 4 Paper cartridge 5 Timing roller 6 Transfer roller 7 Fixing device 10A to 10D Imaging unit 11A to 11D Photosensitive drum 12A to 12D Charging device 13A to 13D Developing device 14 Latent image Forming devices 20A to 20D Toner cartridge 30 Encoder 31 Rotating wheel 32 Sensor 32a Reading gap 33 Sensor substrate 41 Rotating gear 42 Rotating shaft 43 Spacer 44 Shielding member 45 Screw 50 Mounting plate 51 Bearing portion 52 Guide groove 53 Confirmation hole 60 Sensor mounting Plate 61 Holding part 61a Outer surface holding part 61b Inner surface holding part 62 Positioning cut 63 Holding part 64 Start position detection sensor S Recording medium

Claims (6)

In an image forming apparatus provided with an encoder for measuring the rotation of the rotating body by inserting a rotating wheel provided with a large number of slits that rotate with the rotating body into a reading gap of a sensor that detects the slit. ,
The rotating wheel is mounted on the same rotating shaft as the rotating gear that rotates the rotating body,
Image forming apparatus characterized by shielding members for shielding so as to surround at least a portion of the outer peripheral side of the rotary wheel is provided on said rotary gear. In an image forming apparatus provided with an encoder for measuring the rotation of the rotating body by inserting a rotating wheel provided with a large number of slits that rotate with the rotating body into a reading gap of a sensor that detects the slit. ,
A shielding member that shields at least a part of the outer peripheral side of the rotating wheel is provided,
An image forming apparatus, wherein the sensor is mounted on a sensor mounting plate, and a sensor substrate extends outside the sensor in a range where the sensor substrate does not collide with the shielding member . 3. The image forming apparatus according to claim 2 , wherein the rotating wheel is attached to the same rotating shaft as a rotating gear for rotating the rotating body, and the shielding member is provided on the rotating gear. Image forming apparatus. 4. The image forming apparatus according to claim 1, further comprising a start position detection sensor that detects a rotation start position of the rotating wheel. 5. 5. The image forming apparatus according to claim 1 , wherein the shielding member is formed in an annular shape in which a part thereof is cut out so as to surround an outer peripheral side of the rotating wheel. An image forming apparatus.   6. The image forming apparatus according to claim 1, wherein a plurality of photosensitive drums are provided as the rotating body, and the outer diameter of the photosensitive drum is different from that of the other photosensitive drums. An image forming apparatus comprising the above-described encoder.

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