JP4604470B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic process technology.

  Conventionally, in an image forming apparatus using an electrophotographic process technology, an electrostatic latent image is formed on a uniformly charged photoreceptor by scanning light from an optical scanning device, and the electrostatic latent image is developed with toner. Then, the obtained toner image on the photoreceptor is transferred and fixed on a sheet to record the image.

  In the image forming apparatus, there are various ways to attach the optical scanning device (optical box) to the main body frame so that the vibration of the drive system inside the device is transmitted to the optical scanning device and the optical scanning is disturbed and the image quality is not deteriorated. Has been.

  For example, in Patent Document 1 (hereinafter referred to as Conventional Example 1), the mounting reference surface of the optical box of the optical scanning device is brought into contact with the mounting reference surface of the main body frame to prevent a gap formed between the main body frame and the optical box. The structure which can suppress the vibration transmission which goes to an optical box from the main body frame side by pinching | interposing a vibration member is disclosed.

  Further, in Patent Document 2 (hereinafter referred to as Conventional Example 2), a compression spring is sandwiched between the upper and lower portions of the optical box fixing portion, and the spring constants of the upper and lower compression springs are appropriately set so that the forces exerted on the optical box are balanced. It is disclosed that vibration transmission due to rotation of the motor is suppressed by setting.

Further, Patent Document 3 (hereinafter referred to as Conventional Example 3) discloses a configuration in which the four corners of the mounting base of the optical box are supported on the main body frame via vibration-proof rubber, and only the center of gravity is fixed to the main body frame. Yes. It is described that, because of such a configuration, even if vibration is transmitted from the main body, the pedestal (optical box) only moves in the vibration direction and no rotational moment is generated, so that an anti-vibration effect can be obtained.
JP 11-125789 A JP 11-125785 A JP 2000-131635 A

  However, in the above-described conventional example, the image stabilization is not always sufficient, and there is a possibility that the image quality is deteriorated due to vibration transmission to the optical scanning device.

  Specifically, in the conventional example 1, although the vibration isolating member is interposed, the mounting reference surface of the optical box and the mounting reference surface of the main body frame are brought into contact with each other, and both are screwed. May be transmitted to the optical scanning device (housing) and the image quality may deteriorate.

  In the structure of Conventional Example 2, the housing fixing portion is fixed to the main body with a fixing screw, so that vibration on the main body side is transmitted to the housing via the fixing portion. Therefore, there is a possibility that the image quality is deteriorated by this vibration transmission.

  In the structure of Conventional Example 3, only the position of the center of gravity of the mounting base is fixed, so even if the mounting base (optical scanning device) only moves in parallel by vibration transmission, banding may occur depending on the incident angle of the light beam to the photosensitive member. There was an inconvenience that it occurred.

  An object of the present invention is to provide an image forming apparatus capable of reliably preventing vibration transmission and forming a high-quality image in order to solve the above inconvenience.

In order to solve the above problems, an image forming apparatus according to claim 1 includes a housing in which an optical scanning device that scans and exposes a photosensitive member is formed, a main body attachment portion of the image forming apparatus to which the housing is attached, Provided on one of the housing or the main body mounting portion and an elastic member that supports the housing in a state where a reference portion that is disposed on the main body mounting portion and has a mounting reference surface of the housing is separated from the main body mounting portion. A positioning portion that is fitted in a hole formed in the other of the housing or the main body mounting portion and positions the main body mounting portion in a direction parallel to the bottom surface of the housing; and provided in the housing A body portion that is inserted into the inserted insertion hole and is reduced in diameter from the diameter of the insertion hole so as not to contact the inner peripheral surface of the insertion hole, and one end portion of the body portion The screw portion formed and screwed into the screw hole provided in the main body attachment portion, and provided at the other end portion of the trunk portion, and is spaced apart from the housing and is larger than the hole diameter of the insertion hole. And a retaining screw having a head .

  The operation of the image forming apparatus according to claim 1 will be described.

The image forming apparatus of the present invention supports the housing by an elastic member by separating the reference portion having a mounting reference surface of the housing from the body mount. Therefore, the vibration of the body mounting portion side, it is Ru is prevented that is securely blocked by the elastic member for transmitting the optical scanning device.

By the way, if an error occurs in the horizontal positioning parallel to the bottom surface of the housing in the mounting of the housing to the main body mounting portion, the scanning position with respect to the photoconductor is deviated, and appropriate image formation cannot be performed. On the other hand, if this positioning is performed by fastening the main body mounting portion and the housing, the object of blocking vibration transmission cannot be achieved.

  Therefore, in the present invention, a positioning portion provided on one of the housing or the main body mounting portion is fitted into the other hole of the housing or the main body mounting portion, thereby ensuring horizontal positioning accuracy while suppressing vibration transmission. is doing.

  According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, an elastic member is disposed between the main body attaching portion and the housing so as to surround the periphery of the positioning portion. To do.

  The operation of the image forming apparatus according to claim 3 will be described.

  As described above, since the elastic member is disposed so as to surround the periphery of the positioning portion between the main body mounting portion and the housing, transmission is reliably suppressed even if vibration is transmitted from any direction of the main body mounting portion. As a result, good image formation can be performed.

  5. The image forming apparatus according to claim 1, wherein the optical scanning device forms an image by exposing the same scanning line on the photosensitive member a plurality of times. It is characterized by doing.

  The operation of the image forming apparatus according to claim 4 will be described.

  As described above, when the same position on the photoconductor is exposed a plurality of times (in the case of multiple exposure), the shift of the plurality of exposure positions with respect to the same position affects the image quality (particularly the density reduction). Therefore, by suppressing vibration transmission from the main body attaching portion to the optical scanning device by attaching the optical scanning device as described above, it is possible to prevent image quality deterioration and to form a high-quality image.

As described above, in the image forming apparatus according to the present invention , vibration transmission from the main body side to the optical scanning device is suppressed, and better image formation becomes possible.

  An image forming apparatus according to an embodiment of the present invention will be described.

  First, an outline of the image forming apparatus will be described. As shown in FIG. 1, the image forming apparatus 10 is provided inside a casing 12, and around the photosensitive drum 14, the photosensitive belt drum 14 extends along the rotation direction of the photosensitive drum 14. A charger 16 for charging the photosensitive drum 14, an optical scanning device 18 for forming an electrostatic latent image on the charged photosensitive drum 14 by scanning light, and supplying toner to the electrostatic latent image on the photosensitive drum 14 for development. A developing unit 20 (for forming a toner image), a transfer unit 24 for transferring the toner image from the photosensitive drum 14 onto the intermediate transfer belt 22, and a cleaner 26 for removing the toner remaining on the photosensitive drum 14 are provided. .

  The developing device 20 is a rotary type and includes toner rolls 28 for each color of yellow (Y), magenta (M), cyan (C), and black (K). The toner image of each color is formed on the photosensitive drum 14 by rotating to the facing position.

  The intermediate transfer belt 22 disposed below the photoconductor 14 is a toner image transferred from the photoconductor drum 14 to the belt by a transfer device 24. Accordingly, the Y, M, C, and K color toner images formed on the photosensitive drum 14 by the rotation of the developing device 20 are sequentially stacked on the belt to form a full color toner image.

  On the other hand, the toner image laminated on the intermediate transfer belt 22 is transferred by a transfer device 32 to a sheet supplied from the tray 30 along the conveyance path. The sheet onto which the toner image has been transferred is configured to be discharged to the discharge tray 36 after the toner image is fixed by the fixing device 34.

  Next, the optical scanning device 18 will be briefly described. The optical scanning device 18 includes a scanning optical system inside the housing 40. The scanning optical system will be described along a light beam LA emitted from a beam light source (not shown) attached to the side wall of the housing 12. The laser light LA is directed toward the rotary polygon mirror 50 that deflects the laser light LA with a reflecting surface. A collimator lens 42A that makes the light substantially parallel, an aperture 44 that shapes the laser light LA, a half mirror 46, and a line image that has power only in the sub-scanning direction and is long in the main scanning direction in the vicinity of the rotary polygon mirror A cylindrical lens 48 for forming an image is disposed. The light beam LB emitted from another beam light source is also configured to travel on the same optical path as the light beam LA in plan view by the half mirror 46 via the collimator lens 42B and the aperture 44B.

  Along the optical path of the laser beam LA after the rotary polygon mirror 50, an fθ lens 52 having power only in the main scanning direction, a cylinder mirror 54 having power only in the sub-scanning direction, a folding mirror 56, and power only in the sub-scanning direction. A cylinder mirror 58 is provided. The light beam LA reflected by the cylinder mirror 58 passes through the hole 60 of the housing 40 and scans the photosensitive drum 14 to form a line image.

  Next, the attachment portion of the housing 40 to the main body frame 62 of the image forming apparatus 10 will be described in detail. As shown in FIG. 3, the housing 40 is provided with fixing base portions 64 for fixing the optical scanning device 18 to the main body frame 62 in the form of flanges at the four corners of the housing. On the other hand, a bracket 66 having a substantially L-shaped cross section for fixing the optical scanning device 18 is fixed to the main body frame 62 of the image forming apparatus 10. The bracket 66 is attached to the main body frame 62 so as to have a mounted portion 68 projecting vertically from the main body frame 62, and the fixed base portion 64 of the housing 40 is attached to the mounted portion 68.

  More specifically, as shown in FIG. 4, a columnar positioning portion 70 whose end surface is a positioning reference surface on the lower surface side of the fixed base portion 64, that is, the side in contact with the mounted portion 68 of the bracket 66. (Refer FIG. 5) is protrudingly provided. Further, the fixed base portion 64 is provided with an insertion hole 74 for a retaining screw 72 so as to penetrate the positioning portion 70. On the other hand, a screw hole 75 is formed in the attached portion 68 of the bracket 66.

  As shown in FIGS. 4 and 5, the retaining screw 72 is inserted into the head 72 </ b> A having a larger diameter than the insertion hole 74 and the insertion hole 74 so as not to contact the inner peripheral surface of the insertion hole 74. It is comprised from the trunk | drum 72B diameter-reduced rather than the hole diameter of the insertion hole 74, and the screw part 72C diameter-reduced further from the trunk | drum 72B provided in the front-end | tip of the trunk | drum 72B.

  Therefore, when the retaining screw 72 is inserted into the insertion hole 74 of the fixed base portion 64 and the screw portion 72C is screwed into the screw hole 75, the tip of the trunk portion 72B having a diameter larger than the screw portion 72C is attached. I hit it. When the retaining screw 72 is screwed to the attached portion 68 in this way, the head portion 72A of the retaining screw 72 is spaced from the fixed base portion 64 by a distance d1 (hereinafter sometimes referred to as a regulation amount d1). Separate. At this time, the body 72 </ b> B of the retaining screw 72 does not come into contact with the inner peripheral surface of the insertion hole 74.

  Further, the anti-vibration rubber 76 inserted and disposed between the fixed base portion 64 and the attached portion 68 has a substantially circular disk shape, and a hole portion 78 into which the positioning portion 70 is inserted is formed at the center portion. (See FIG. 5). A height h2 of the vibration isolating rubber 76 is larger than a protruding amount (height of the positioning portion 70) h1 of the positioning portion 70 from the fixed base portion 64. That is, when the anti-vibration rubber 76 is interposed between the fixed base portion 64 and the attached portion 68, the positioning portion 70 is separated from the attached portion 68.

  A boss 80 for positioning in the XY direction (a direction parallel to the bottom surface of the housing 40) is formed on the lower surface of the fixed base portion 64 so as to protrude. The positioning boss 80 is positioned in the XY direction of the housing 40 by being fitted into a fitting hole 82 provided in the attached portion 68. At this time, the effective insertion amount d2 of the positioning boss 80 with respect to the fitting hole 82 is set larger than the regulation amount d1 (see FIG. 4).

  Further, an anti-vibration rubber 86 in which a positioning boss insertion hole 84 is formed is disposed between the fixed base portion 64 and the attached portion 68 around the positioning boss 80. The height of the anti-vibration rubber 86 is h2 like the anti-vibration rubber 76.

  The operation of the image forming apparatus configured as described above will be described.

  The image forming apparatus 10 employs a configuration in which the optical scanning device 18 (housing 40) is attached to the main body frame 62 (attached portion 68) without using fastening means and is supported only by the vibration isolating rubbers 76 and 86. Therefore, vibration transmission from the main body to the optical scanning device 18 can be surely cut off, and high-quality image formation is possible.

  Since the anti-vibration rubbers 76 and 86 have shapes (cylindrical shapes) surrounding the positioning portion 70 and the positioning boss 80, respectively, vibration transmission can be more reliably blocked.

Note that the housing 40 is supported only by the anti-vibration rubbers 76 and 86, and the positioning accuracy in the direction perpendicular to the bottom surface of the housing 40 (hereinafter referred to as the Z direction) may not be ensured. It can be solved by designing as follows. That is, when a slight error occurs in the position accuracy of the housing 40 in the Z direction, an error occurs in the optical path length of the light beam L with respect to the photosensitive drum 14. As a result, the thickness of the anti-vibration rubbers 76 and 86 is within the allowable range in terms of image quality even if the beam spot diameter on the photoconductor changes due to the deterioration (sagging) of the anti-vibration rubbers 76 and 86 over time. The sheath material can be selected. For example, if the beam diameter is 50 μm, an object depth error of about 3 mm has little effect on the image quality. In general, it is considered that the amount of settling of the anti-vibration rubbers 76 and 86 is about 20% of the original thickness. Therefore, even if the thickness of the anti-vibration rubber is set to 1 mm, the error of the subject depth due to the settling is about 0.2 mm. It is considered to be well within the allowable range of 3 mm, and the image quality is not affected at all. As described above, by selecting the thickness of the vibration isolating rubbers 76 and 86, it is possible to form an image with high image quality even if the housing 40 is supported by only the vibration isolating rubbers 76 and 86.

  Further, in the direction parallel to the bottom surface of the housing 40 (hereinafter referred to as the XY direction), since the positioning boss 80 of the housing 40 is fitted in the fitting hole 82, the positioning in the XY direction can be ensured. It is possible to prevent the image quality from being deteriorated due to the occurrence of the scanning position shift due to the position shift in the direction.

  Although the positioning boss 80 is fitted in the fitting hole 82, there is a risk of vibration transmission. However, since the cylindrical vibration-proof rubber 86 is disposed so as to surround the positioning boss 80, Vibration transmission from the mounting portion 68 to the positioning boss 80 is sufficiently suppressed, and image quality deterioration can be prevented.

  Further, the head 72A forms a gap d1 between the head 72A and the fixed base portion 64 by screwing the retaining screw 72 into the attached portion 68 and abutting the body portion 72B against the attached portion 68. . Furthermore, since the diameter of the trunk portion 72B of the retaining screw 72 is smaller than the hole diameter of the insertion hole 74, there is no contact. Therefore, the retaining screw 72 does not come into contact with the housing 40, and transmission of vibration to the housing 40 via the retaining screw 72 is reliably avoided.

  Further, a gap (restricted amount) d1 is formed between the head 72A of the retaining screw 72 and the fixed base portion 64, and this restricted amount d1 is set smaller than the effective insertion amount d2 of the positioning boss 80. Therefore, even if the housing 40 (fixed base portion 64) vibrates within the range of the regulation amount d1 due to vibration during transportation or the like, the positioning boss 80 does not come out of the fitting hole 82. That is, it is possible to prevent an error in positioning of the optical scanning device in the X and Y directions due to vibration during transportation.

  Furthermore, when the same position (on the same scanning line) on the photoreceptor is exposed a plurality of times (in the case of multiple exposure), a plurality of exposure position shifts with respect to the same position may lead to a decrease in density and generation of white stripes. However, since the anti-vibration effect is improved, it is possible to reliably prevent density unevenness and white streaks due to vibration.

  Further, it is possible to reliably prevent the image quality from being deteriorated due to the impact when the rotary developing device 20 stops rotating is transmitted to the optical scanning device 18.

  In this embodiment, the retaining screw (stepped screw) 72 is used as a member for preventing the housing 40 from falling off. However, a sheet metal or the like may be used as long as a predetermined interval can be set with respect to the fixed base portion 64. It is also possible to substitute a formed bracket, a cover provided on the upper surface of the housing, or the like.

  Further, in this embodiment, the positioning boss 80 is provided on the housing 40 side and the fitting hole 82 is provided on the attached portion 68 side.

  Furthermore, in the present embodiment, the anti-vibration rubbers 76 and 86 are separated, but may be integrated.

1 is a schematic view of an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view of an optical scanning device according to an embodiment of the present invention. It is an attachment state explanatory view of the optical scanning device to the body frame concerning one embodiment of the present invention. It is principal part sectional drawing of an attachment part. It is a principal part disassembled perspective view of a positioning part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Image forming apparatus 18 ... Optical scanning device 40 ... Housing 68 ... Mounted part 70 ... Positioning part 76, 86 ... Anti-vibration rubber

Claims (3)

A housing in which an optical scanning device for scanning and exposing a photosensitive member is formed;
A main body attaching portion of an image forming apparatus to which the housing is attached;
An elastic member disposed on the main body mounting portion and supporting the housing in a state in which a reference portion having a mounting reference surface of the housing is separated from the main body mounting portion;
Positioning in a direction parallel to the bottom surface of the housing with respect to the main body mounting portion provided in one of the housing or the main body mounting portion and fitted in a hole formed in the other of the housing or the main body mounting portion. Positioning part for
The body is inserted into an insertion hole provided in the housing, and is formed at one end portion of the body part, the body part having a diameter smaller than the diameter of the insertion hole so as not to contact the inner peripheral surface of the insertion hole. A screw portion screwed into a screw hole provided in the main body attaching portion; and a head portion provided at the other end portion of the trunk portion and spaced apart from the housing and having a diameter larger than the hole diameter of the insertion hole. And a retaining screw,
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein an elastic member is disposed between the main body attachment portion and the housing so as to surround the periphery of the positioning portion.   The image forming apparatus according to claim 1, wherein the optical scanning device forms an image by exposing the same scanning line on the photosensitive member a plurality of times.

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