JP2006076250A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device which prevents a fixing means from jumping out of a holding member to hold an optical box and is reducible in size. <P>SOLUTION: The image forming device has a photosensitive body, a scanning means to scan the photosensitive body with light in accordance with image information, an optical box to store the scanning means and a holding member to hold the optical box, and forms an image on a recording material. The holding member is formed with protrusions on positions for holding the optical box. Recesses formed at the optical box are fitted to the protrusions. The protrusions of the holding member and the recesses of the optical box are fixed by a fixing means to secure the optical box to the holding member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to an image forming apparatus having a scanning optical device that scans a photosensitive member with light according to image information.

In an image forming apparatus having a scanning optical device such as a laser scanner, the scanning optical device is generally attached to the image forming apparatus main body by fastening with screws.
JP 2000-180766 A Japanese Patent Laid-Open No. 5-107491 JP-A-5-119276 JP 2000-249955 A

  However, the conventional general attachment method has the following problems.

  In recent years, laser beam printers and digital copying machines have been required to be small and thin, and the gaps between the scanning optical device and the parts and units arranged immediately below the scanning optical device have to be reduced. However, in the conventional attachment method, a screw for attaching the scanning optical device to the stay protrudes from the back surface of the stay. There is a photosensitive member that is scanned by the scanning optical device on the side opposite to the scanning optical device arrangement surface side of the stay to which the scanning optical device is attached. In general printers and copiers, this photosensitive member is used alone or developed. The image forming apparatus main body is a cartridge that is integral with the image forming apparatus and the like, and is detachable from the image forming apparatus main body. Therefore, the cartridge must be designed so as not to interfere with the screw protruding from the stay when the cartridge is taken in and out, and a dead space is generated by the amount of the screw protruding from the stay, which hinders downsizing of the image forming apparatus. . Although it is conceivable to shorten the screw so that the tip of the screw does not jump out of the stay, in that case, a sufficient fastening force may not be obtained.

  In order to prevent interference with the screw, the cartridge may be provided with a relief groove, but the shape of the cartridge becomes complicated and the volume for filling the toner becomes small.

  In order to solve the above problems, the present invention provides a photoconductor, a scanning unit that scans the photoconductor with light according to image information, an optical box that houses the scanning unit, and a holding member that holds the optical box. In the image forming apparatus for forming an image on a recording material, a convex portion is provided at a position of the holding member for holding the optical box, and a concave portion provided in the optical box enters the convex portion. The optical box is fixed to the holding member by fixing the convex portion of the holding member and the concave portion of the optical box by a fixing means.

  Since the protrusion of the fixing means from the holding member that holds the optical box can be suppressed, it is effective in reducing the size of the image forming apparatus.

(First embodiment)
FIG. 1 is a cross-sectional view showing an image forming apparatus 26 of this embodiment. In the figure, reference numeral 5 denotes a scanning optical device (scanning means) described later. The scanning optical device 5 that emits the laser beam 8 is installed on an optical bench (holding member) 23, and a process cartridge 9 including a photosensitive drum 19 that is scanned by the laser beam 8 is disposed below the scanning optical device 5. The image forming apparatus 26 is incorporated into the image forming apparatus 26 so as to be disposed. The process cartridge is removable in the direction of arrow P.

  The recording material M such as paper or OHT supplied from the paper feed cassette 15 or the tray 13 is transported along the transport path S by transport rollers (14, 11, 10, 20, 22, 1).

  A laser beam 8 emitted from an emission port provided at the lower part of the optical box of the scanning optical device 5 scans on the photosensitive drum 19 to form a latent image based on image information on the surface of the photosensitive drum. The latent image formed on the surface of the photosensitive drum is developed with toner in the developing unit 17, and the toner image formed on the photosensitive drum is transferred to a recording material that moves along the conveyance path S by the transfer roller 18.

  The recording material to which the toner image has been transferred is heated when passing through the fixing unit 21, and the toner on the recording material is fixed to the recording material. Thereafter, the recording material is output from the image forming apparatus.

  FIG. 2 is a diagram for explaining the configuration of the scanning optical device 5 in the first embodiment. The laser beam 33 emitted from the laser light source unit 27 is limited to a predetermined beam diameter by the optical aperture 29 formed in the optical box 28, is condensed only in the sub-scanning direction by the cylindrical lens 30, and the laser beam of the rotating polygon mirror 31 is collected. The light is condensed on the reflecting surface 32 in a long line shape in the main scanning direction. The rotary polygon mirror 31 is rotationally driven by a drive motor 34 and deflects the incident laser beam 33. The deflected laser beam passes through the fθ lens 35, is reflected by the folding mirror 36, and is condensed on the photosensitive drum 19. As a result, an electrostatic latent image corresponding to the image information is formed on the photosensitive drum 19. A part of the deflected laser beam is guided to the synchronization detection sensor 37 to detect the synchronization of the writing position in the main scanning direction.

  The upper opening (opening) of the optical box 28 is closed by a metal optical lid 38. The optical lid 38 is fixed together with the optical box 28 to a metal optical stand (holding member) 23 by screws (fixing means) 40. The optical bench 23 is a part of the housing of the image forming apparatus 26.

  Next, the manner in which the scanning optical device 5 is fixed will be described in more detail with reference to FIG. FIG. 3 is a partial cross-sectional view of the fixing portion 43 provided at the four corners of the scanning optical device, taken along the ZX plane around the screw center. The optical lid 38 and the optical bench 23 are formed with diaphragms (convex portions) 41 and 42 that face each other. The seat surface (recessed portion of the optical box) 45 is a reference plane in the Z direction of the scanning optical device 5 and is provided at the approximate center of the optical box in the Z direction. The seat surface 45 is mounted on the upper surface 44 of the diaphragm 42 of the optical bench 23, and the position of the scanning optical device in the Z direction is determined.

  According to this embodiment, even if the optical box and the optical bench are fastened with screws, the screw 40 is stored in the concave portion (the valley side of the convex portion) of the diaphragm provided in the optical bench 23. Screw tip does not protrude from. Therefore, there is no possibility that the upper surface of the cartridge housing contacts the tip of the screw when the cartridge 9 is attached or detached. That is, since the upper surface of the cartridge can be designed to approach the back of the optical bench as much as possible, it can contribute to the downsizing of the image forming apparatus. Similarly, since the screw 40 is stored in the concave portion (the valley side of the convex portion) of the diaphragm 41 provided in the optical lid 38, the screw head of the screw 40 does not protrude from the upper surface of the optical lid. Therefore, the paper discharge tray 46 can be disposed as close as possible to the upper surface of the optical lid, which can contribute to the downsizing of the image forming apparatus.

  Moreover, since the diaphragm is formed in the optical lid and the optical bench, the strength of the optical lid and the optical bench is improved. That is, even if a thin plate is used, sufficient strength can be maintained, so that an inexpensive and compact scanning optical device can be provided. In addition, since the aperture of the optical lid also serves as a screw guide, the assemblability when the screw is fixed is improved. In addition, the aperture of the optical lid has an effect of suppressing dust from entering the scanning optical device. Therefore, it is possible to provide an image forming apparatus with excellent durability capable of outputting a good image free from density unevenness and streaks.

  In addition, if the optical bench, the optical lid, and the screw are made of metal and the optical bench is electrically grounded as in this embodiment, it is possible to prevent radiation noise easily and inexpensively without adding a special separate member. Countermeasures are possible. In addition, the screw for attaching the optical box to the optical bench also serves as a fastening means for the optical box and the optical lid, thereby reducing the cost.

  In addition, since the optical box and the optical stand are fixed at a height substantially equal to the height of the light source in the Z direction, when the temperature inside and around the scanning optical device rises due to the operation of the scanning optical device, the optical box It expands toward both sides in the Z direction around the screw fixing height. That is, the optical box expands toward both sides in the Z direction with the light source height as the center. Therefore, the thermal deformation of the portion where the laser beam passes and reflects in an optical element such as a cylindrical lens, an fθ lens, and a folding mirror hardly occurs. That is, it is possible to extremely suppress deterioration of optical performance due to temperature rise.

(Second embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. The schematic cross section of the image forming apparatus according to the present embodiment is the same as that of the first embodiment, and thus the description thereof is omitted. The same parts as those in the first embodiment are denoted by the same reference numerals.

  FIG. 4 is an enlarged cross-sectional view of the fixing portion 243 of the image forming apparatus according to the present exemplary embodiment. The optical lid 238 of this embodiment is not fixed by the screw 40, and the screw 40 fixes only the optical box 28 and the optical bench 23. The optical lid 238 is provided with a hole 241 through which the screw 40 is passed.

  Since the screw 40 is stored in the concave portion (the valley side of the convex portion) of the diaphragm provided in the optical bench 23 even if the optical box and the optical bench are fastened with screws, this embodiment is also similar to the first embodiment. The screw tip does not protrude from the back of the optical bench. Therefore, there is no possibility that the upper surface of the cartridge housing contacts the tip of the screw when the cartridge 9 is attached or detached. That is, since the upper surface of the cartridge can be designed to approach the back of the optical bench as much as possible, it can contribute to the downsizing of the image forming apparatus. Similarly, since the screw 40 is stored in the concave portion on the upper side of the optical box, the screw head of the screw 40 does not protrude from the upper surface of the optical lid. Therefore, the paper discharge tray 46 can be disposed as close as possible to the upper surface of the optical lid, which can contribute to the downsizing of the image forming apparatus.

  In addition, since the diaphragm is formed on the optical bench, the strength of the optical bench is improved. That is, even if a thin plate is used, sufficient strength can be maintained, so that an inexpensive and compact scanning optical device can be provided. In addition, since the hole 241 of the optical lid also serves as a screw guide, the assemblability when fixing the screw is improved.

(Third embodiment)
FIG. 5 is a sectional view of the image forming apparatus 126 according to the third embodiment of the present invention. FIG. 6 is an enlarged view of a fastening portion between the optical bench and the optical box.
Reference numeral 105 denotes a scanning optical apparatus that accommodates the same scanning means as in the first embodiment. The scanning optical device 105 that emits the laser beam 108 is fixed to the optical bench 123 that is a part of the housing of the image forming apparatus 126 by screws 146. The cartridge 109 incorporating the photosensitive drum 119 and the like irradiated with the laser beam 108 is incorporated into the image forming apparatus 126 so as to be disposed above the scanning optical apparatus 105. The cartridge 109 is detachable in the arrow P direction.

  An optical element group such as a laser light source unit, a laser beam, an optical aperture, a cylindrical lens, a rotary polygon mirror, a drive motor, an fθ lens, and a synchronization detection sensor are arranged in the same manner as in the first embodiment.

  The upper opening of the optical box 128 is closed by a metal optical bench 123. The optical bench 123 is provided with an aperture window 100, and the laser beam reflected by the folding mirror 136 passes through the aperture window and is condensed on the photosensitive drum.

  Next, the manner in which the scanning optical device 105 is fixed will be described in more detail with reference to FIG. FIG. 6 is a partial cross-sectional view of the fixing portion 143 provided at the four corners of the scanning optical device, taken along the ZX plane around the screw center. The seating surface 145 is a Z-direction reference surface of the scanning optical device 5 and is provided at the approximate center of the optical box in the Z direction. A diaphragm 142 is formed on the optical bench 123, and a seating surface (a concave portion of the optical box) 145 is brought into contact with the end surface 144 of the diaphragm 142 to determine the position of the scanning optical device in the Z direction.

  According to the third embodiment, since the screw 146 is stored in the concave portion (the valley side of the convex portion) of the diaphragm provided in the optical bench 123, the screw tip does not protrude from the upper surface of the optical bench. Therefore, there is no possibility that the lower surface of the cartridge housing comes into contact with the screw tip when the cartridge is detached. That is, even if the lower surface of the cartridge is brought as close as possible to the upper surface of the optical bench, the process cartridge can be smoothly attached and detached, which can contribute to downsizing of the image forming apparatus.

  In addition, since the diaphragm is formed on the optical bench, the strength of the optical bench is improved. That is, the same effect as in the first embodiment can be obtained.

  In addition, since the optical box and the optical stand are fixed at a height substantially equal to the height of the light source in the Z direction, when the temperature inside and around the scanning optical device rises due to the operation of the scanning optical device, the optical box It expands toward both sides in the Z direction around the screw fixing height. That is, the same effect as in the first embodiment can be obtained.

  Further, the third embodiment is a preferable configuration that can realize cost reduction and downsizing of the image forming apparatus because the optical bench also functions as an optical lid.

  In addition, this invention is not limited to the above-mentioned Examples 1-3, An optical lid and an optical stand may be what kind of materials, such as not only a metal but resin. The aperture shape of the optical lid and the optical bench may be any shape. Of course, it goes without saying that the location of the fixing portion of the optical box and the number of screws are not limited to the above-described embodiments.

1 is a cross-sectional view of an image forming apparatus according to first and second embodiments of the present invention. 1 is a perspective view of a scanning optical device mounted on an image forming apparatus of the present invention. It is an expanded sectional view of the fixing | fixed part of the optical stand and scanning optical means of 1st Example of this invention. It is an expanded sectional view of the fixing | fixed part of the optical stand and scanning optical means of 2nd Example of this invention. It is sectional drawing of the image forming apparatus of 3rd Example of this invention. It is an expanded sectional view of the fixing | fixed part of the optical stand and scanning optical means of 3rd Example of this invention.

Explanation of symbols

5 Scanning Optical Device 9 Cartridge 23 Optical Stand 28 Optical Box 38 Optical Cover 42 Aperture (convex)
45 Seat (recess)
46 Screw (fixing means)
123 Optical stand and optical lid 128 Optical box 142 Diaphragm part (convex part)
145 Seat (concave)
146 Screw (fixing means)

Claims (6)

An image that forms an image on a recording material, which includes a photosensitive member, a scanning unit that scans the photosensitive member with light according to image information, an optical box that houses the scanning unit, and a holding member that holds the optical box. In the forming device,
A convex portion is provided at a position of the holding member that holds the optical box, and a concave portion provided in the optical box enters the convex portion, and the convex portion of the holding member and the concave portion of the optical box are fixed. An image forming apparatus, wherein the optical box is fixed to the holding member by being fixed by means.   The image forming apparatus according to claim 1, wherein the apparatus further includes a lid that covers an opening of the optical box, and the fixing unit fixes the lid, the optical box, and the holding member. apparatus.   The image forming apparatus according to claim 2, wherein the holding member, the fixing unit, and the lid are made of metal, and the lid is grounded via the fixing unit and the holding member.   The lid has a convex portion into which the fixing means enters, the convex portion of the lid contacts one surface of the concave portion of the optical box, and the convex portion of the holding member contacts the other surface of the concave portion of the optical box. The image forming apparatus according to claim 2, wherein the image forming apparatus is in contact.   The apparatus further includes a lid that covers the opening of the optical box, and the lid is provided with a hole through which the fixing means is passed, and the fixing means passes through the hole without passing through the lid. The image forming apparatus according to claim 1, wherein the holding member is fixed. The image forming apparatus according to claim 1, wherein the holding member is a lid that covers an opening of the optical box.

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