JP2008129523A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which is equipped with an encoder for measuring the rotating speed of a rotational body and in which a rotary wheel having a number of slits rotating as the rotational body rotates is adapted to be inserted into the reading clearance of the sensor detecting the slits, such that the sensor can be simply and exactly set in an appropriate position. <P>SOLUTION: The image forming apparatus is equipped with the encoder 30 for measuring the rotating speed of the rotational body by inserting a rotary wheel 31 provided with the number of the slits rotating as the rotational body rotates into the reading clearance 32a of the sensor 32 detecting the slit, in which a mounting plate 50 provided with a bearing section 52 for rotatably holding the rotary wheel is provided with a guide groove 52 for sliding and guiding a sensor wearing plate 60 worn with the sensor, and the sensor wearing plate is provided with a holding section 61 for holding the edge of the guide groove of the mounting plate so as to put the edge of the guide groove of the mounting plate between the sensor wearing plate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and in particular, controls the rotational speed of a rotating body by measuring the rotational speed of a rotationally driven rotating body such as a photosensitive drum or an intermediate transfer body with an encoder. In the image forming apparatus configured as described above, when the encoder is set on the rotating body, a rotating wheel having a large number of slits rotating with the rotating body is inserted into the reading gap of the sensor that detects the slit. As described above, the present invention is characterized in that the operation of setting the sensor at an appropriate position can be performed easily and accurately.

  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, and the rotational speed of the rotating body is controlled. 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.

  However, since the reading gap of the above sensor is very narrow, when the sensor is mounted such that the rotating wheel is inserted into the reading gap of the sensor as described above, the rotating wheel is appropriately fitted in the reading gap of the sensor. There was a problem that the rotating wheel collided with the sensor and bent without being inserted, and reading by the sensor could not be performed properly.

  For this reason, in the prior art, when attaching the sensor so that the rotating wheel is inserted into the sensor reading gap, a positioning boss is provided on the sensor mounting member on which the sensor is mounted, and the rotating wheel is held rotatably. The panel member is provided with a notch for positioning, and the sensor mounting member on which the above sensor is mounted is slid to the panel member on which the rotating wheel is rotatably held, and the positioning boss provided on the sensor mounting member is moved to the panel. There has been proposed a technique in which a sensor and a rotating wheel are positioned by abutting against a positioning notch provided on a member (see, for example, Patent Document 1).

However, even when the positioning of the sensor and the rotating wheel is performed as described above, the sensor can still be set at an appropriate position with respect to the rotating wheel due to various accumulated errors during mounting or the like. There was a problem that became difficult.
JP 2003-247858 A

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems when an encoder is set on a rotating body in an image forming apparatus including an encoder that measures the rotational speed of the rotating body. An object is to enable a sensor to be easily and accurately set at an appropriate position by inserting a rotary wheel having a large number of slits that rotate with the body into a reading gap of a sensor that detects slits. It is what.

  In the present invention, in order to solve the above-described problems, a rotating wheel provided with a large number of slits that rotate with a rotating body is inserted into a reading gap of a sensor that detects the slits, and In an image forming apparatus provided with an encoder for measuring the rotational speed of a rotating body, a sensor mounting plate on which the sensor is mounted is slid on a mounting plate provided with a bearing portion that rotatably holds the rotating wheel. And a holding portion for holding the sensor mounting plate so as to sandwich the edge portion of the guide groove of the mounting plate.

  Further, in the image forming apparatus of the present invention, a confirmation hole for confirming the mounting position of the sensor mounting plate on the mounting plate in order to confirm whether the sensor mounting plate is properly mounted on the mounting plate. Is preferably provided.

  In addition, in the image forming apparatus of the present invention, when providing the holding portion for holding the sensor mounting plate so as to sandwich the edge of the guide groove of the mounting plate as described above, the edge of the guide groove of the mounting plate is provided. It is possible to provide an outer surface holding portion positioned on the outer surface and an inner surface holding portion positioned on the inner surface of the edge portion.

  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, the rotational speed of the rotating body is adjusted by inserting a rotating wheel provided with a large number of slits that rotate with the rotating body into the reading gap of the sensor that detects the slit. When providing an encoder for measurement, an edge portion of a guide groove formed on a mounting plate provided with a bearing portion for rotatably holding a rotating wheel is sandwiched by a holding portion provided on a sensor mounting plate on which a sensor is mounted. In this manner, the sensor mounting plate is slid along the guide groove formed in the mounting plate so that the sensor mounting plate is mounted on the mounting plate.

  In this case, the sensor mounting plate is slid along the guide groove formed in the mounting plate in a state where the sensor mounting plate is held by the holding portion so as not to rattle the mounting plate. It becomes easy to set the sensor so that the rotating wheel is properly inserted in the reading gap of the sensor, and the rotating wheel collides with the sensor and bends. Thus, reading by the sensor can be performed appropriately.

  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, the rotational speeds of the photosensitive drums having different outer diameters are measured, and the photosensitive members having different outer diameters are measured. When the rotational speed of the drum is controlled, the above-described image shift 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.

  In addition, 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 stored in the apparatus main body 1. It is designed to be detachably attached to the.

  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. Encoders are also provided for the drive rollers 3a for rotationally driving the photosensitive drums 11A to 11C and the intermediate transfer belt 3, and the rotational speeds of these are measured. It is also possible to control.

  Next, a large number of slits (not shown) that rotate with the rotating body are provided for the rotating body including the photosensitive drums 11A to 11D and the driving roller 3a of the intermediate transfer belt 3 as described above. A specific description will be given of the case where the encoder 30 is provided such that the rotating wheel 31 is inserted into the reading gap 32a of the sensor 32 that detects the slit.

  Here, in this embodiment, as shown in FIGS. 2A and 2B, the rotating wheel is mounted on the rotating shaft 42 to which the rotating gear 41 that rotates with the rotating body as described above is attached. 31 is attached to a predetermined position through a spacer 43 between the rotary gear 41 and the bearing 31 provided on the mounting plate 50 so as to be rotatably supported.

  The mounting plate 50 is provided with a pair of guide grooves 52 for sliding and guiding the sensor mounting plate 60 on which the sensor 32 is mounted, and the sensor mounting plate 60 is mounted in the vicinity of the bearing portion 51. A confirmation hole 53 for confirming the position is provided, and in order to prevent the sensor mounting plate 60 from being mounted upside down, the restraining piece 54 projects outward from the inside of each guide groove 52. It is bent and formed like this.

  Further, in the sensor mounting plate 60, as shown in FIGS. 3A and 3B, a pair of sensors 32 is attached to the lower surface of the sensor mounting plate 60 with a reading gap 32a facing each other with a required interval. Yes.

  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. A gripping portion 63 for gripping the sensor mounting plate 60 is provided.

  When the sensor mounting plate 60 is attached to the mounting plate 50 by inserting the rotating wheel 31 into the reading gap 32a of the sensor 32 as described above, the grip provided on the sensor mounting plate 60 is held. As shown in FIG. 4, the outer surface holding portion 61a of 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, as shown in FIG. 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 plate 60 so that 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. As shown in FIG. 6, the positioning notch 62 provided is brought into contact with the bearing portion 51 provided in the mounting plate 50 and confirmed through the confirmation hole 53 provided in the sensor mounting plate 60. In addition, the sensor mounting plate 60 is attached to the mounting plate 50 by screws 44 from above the mounting plate 50.

  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 31 is inserted into the reading gap 32 a of the sensor 32 mounted on the sensor mounting plate 60. Will be inserted properly.

1 is a schematic explanatory diagram of an image forming apparatus according to an embodiment of the present invention. In the image forming apparatus in the above embodiment, a schematic front view and a schematic plan view showing a state in which a rotating wheel of an encoder is rotatably provided on a mounting plate. FIG. 5 is a schematic front view and a schematic plan view illustrating 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, a schematic front view showing a state in which the sensor mounting plate is slid to a predetermined position along the guide groove provided in the mounting plate and the rotating wheel is inserted into the sensor reading gap. It is a figure and a schematic plan view. FIG. 5 is a schematic perspective view showing a state in which the sensor mounting plate is slid to a predetermined position along a guide groove provided on the mounting plate and mounted on the mounting plate in the image forming apparatus according to the embodiment.

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 41 Rotating gear 42 Rotating shaft 43 Spacer 44 Screw 50 Mounting plate 51 Bearing portion 52 Guide groove 53 Checking hole 54 Suppression piece 60 Sensor mounting plate 61 Holding Part 61a outer surface holding part 61b inner surface holding part 62 positioning notch 63 gripping part S recording medium

Claims (4)

  An image forming apparatus provided with an encoder for measuring the rotational speed of the rotating body by inserting a rotating wheel provided with a large number of slits rotating with the rotating body into a reading gap of a sensor for detecting the slit In addition, a guide groove for sliding and guiding the sensor mounting plate on which the sensor is mounted is provided on the mounting plate provided with a bearing portion that rotatably holds the rotating wheel, and the sensor mounting plate An image forming apparatus comprising: a holding portion that holds the edge of the guide groove of the mounting plate so as to sandwich the edge.   2. The image forming apparatus according to claim 1, wherein a confirmation hole for confirming a mounting position of the sensor mounting plate is provided in the mounting plate.   3. The image forming apparatus according to claim 1, wherein the holding portion provided on the sensor mounting plate includes an outer surface holding portion located on an outer surface of an edge portion of the guide groove of the mounting plate and an edge portion. An image forming apparatus comprising an inner surface holding portion located on the inner surface.   4. 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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