JP5031657B2 - Optical scanning device - Google Patents

Description

  The present invention relates to an optical scanning device applied to an image forming apparatus such as a laser beam printer that forms a recorded image using laser light.

  In an optical scanning device used for a laser beam printer or the like, the following problem arises when the light source unit composed of a semiconductor laser and its driving circuit board is mounted exposed outside the housing. There was concern.

  In the case of the above configuration, when assembling / adjusting the optical scanning device, during transportation, or when incorporating the optical scanning device into the laser beam printer, the configuration of the operator's hand, clothes, packing material, or the periphery of the laser beam printer A member or the like may come into contact with the circuit board. In such a case, there has been a concern that the variable resistance for adjusting the amount of laser light may fluctuate, causing problems such as defective image density.

Therefore, for the purpose of preventing contact with the variable resistor on the circuit board and preventing fluctuations in the amount of laser light, a configuration or variable in which a protective member having a height protruding from the variable resistor is provided in the vicinity of the variable resistor. The structure which protects resistance by covering with a metal plate is proposed. (For example, see Patent Document 1)
JP 2006-91453 A

  On the other hand, in the case where the light source unit is exposed to the outside of the housing, the light source unit is inserted into a fitting hole formed on a side surface of the housing and attached by screwing or the like.

  In such a configuration, there has been a concern that minute dust may enter through a small gap between the fitting portion and the housing and the cover member covering the fitting portion, and the optical member in the housing is contaminated.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to prevent contact with a variable resistor on a circuit board and to improve dustproof performance of a light source unit.

In order to achieve the above object, the present invention provides:
A light source that emits laser light,
A variable resistor for adjusting the light quantity of the light source; and
A circuit board on which the variable resistor is mounted and drives the light source;
A light source unit having
An optical box to which the light source unit is attached;
A lid member for closing the optical box;
An optical scanning device in which the circuit board is disposed outside the optical box,
A protective member that covers at least the variable resistor of the circuit board and covers a gap between the optical box and the lid member in the vicinity of an attachment portion of the optical box to which the light source unit is attached. To do.

ADVANTAGE OF THE INVENTION According to this invention, while preventing the contact to the variable resistance on a circuit board, it becomes possible to improve the dustproof performance of a light source part.

  The best mode for carrying out the present invention will be exemplarily described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

  Embodiment 1 of the present invention will be described below.

  FIG. 6 is a diagram for explaining a schematic configuration of the image forming apparatus according to the present exemplary embodiment.

  In FIG. 6, reference numeral 101 denotes a printer main body as an image forming apparatus. An image forming unit 102 is provided in the printer main body 101 and forms an image by an electrophotographic method. The image forming unit 102 includes a photosensitive drum (hereinafter referred to as a photosensitive member) 103 as an image carrier that forms a toner image (developer image), and a transfer roller that transfers the toner image formed on the photosensitive member 103 to a recording material P. 104 etc. are provided.

  In the image forming unit 102 having such a configuration, when an image forming operation is started, first, the optical scanning device 100 irradiates the photoconductor 103 with a laser beam L corresponding to an image signal. Then, by irradiating with such laser light L, a latent image is formed on the photosensitive member 103.

  Next, the latent image formed on the photoconductor 103 is developed with toner as a developer stored in the toner cartridge 105, thereby forming a toner image (visible image) on the photoconductor 103. . In parallel with the toner image forming operation, the recording material P is fed from the recording material storage cassette. Then, the recording material P is conveyed to a transfer portion constituted by the photosensitive member 103 and the transfer roller 104 in synchronization with the toner image formed on the photosensitive member 103 by the conveying roller and the registration roller.

  In this transfer portion, the toner image is transferred to the recording material P by applying a bias to the transfer roller 104.

  The recording material P to which such a toner image has been transferred is then conveyed to the fixing device 107 and heated by the fixing device 107 so that the toner image is fixed to the recording material P.

  Next, the optical scanning device 100 of this embodiment will be described.

  FIG. 1 is a perspective view illustrating a schematic configuration of an optical scanning device 100 according to the present embodiment. FIG. 2 is a perspective view illustrating a schematic configuration of the optical scanning device 100 according to the present embodiment. FIG. 2 illustrates a state in which a cover member 31 serving as a lid member for closing the optical box 30 is removed. .

  As shown in FIG. 2, the light source device 10 serving as a light source unit is a semiconductor laser 11 that is modulated according to image information, a collimator lens 12 that makes the laser light substantially parallel, and a control that drives the semiconductor laser 11. The circuit board 20 having an IC 21 or the like is used. The laser light emitted from the light source device 10 passes through a cylindrical lens 13 having a curvature in the sub-scanning direction, and then the light beam is limited by the aperture stop 14 to be condensed linearly on the reflecting surface of the rotary polygon mirror 15.

The rotary polygon mirror 15 is rotated at a high speed by a drive motor 16, and the rotary polygon mirror 15 is rotated.
The laser light reflected by the laser beam passes through the imaging lenses 17 and 18 having the characteristic of performing constant speed scanning with the laser light (fθ characteristic) on the surface of the photosensitive member in order. Thereafter, the laser light is guided to the photosensitive member 103 by the reflection mirror 19.

  In the figure, 51 is a horizontal synchronization sensor for detecting the writing start timing of the laser beam, and 52 is a mirror for guiding the laser beam to this horizontal synchronization sensor.

  The collimator lens 12 is assembled with its position adjusted with high accuracy in the light source device 10 of the optical scanning device 100 in order to form an image of a laser beam in a desired beam shape on the photosensitive member. Further, the imaging lenses 17 and 18 are also attached to the optical box 30 with high accuracy by known means such as adhesion.

  The circuit board 20 is mounted with variable resistors 22 and 23 for adjusting the amount of laser light, and the resistance can be adjusted to a desired laser amount by manipulating the resistance value.

  After performing these adjustments, as shown in FIG. 1, the upper portion of the optical box 30 is covered by the cover member 31, and the cover member 31 is fixed to the optical box 30 by the screws 32, so that the optical scanning device 100 is Composed.

  Furthermore, in the optical scanning device 100 of the present embodiment, as shown in FIG. 1, the protective sheet 33 is disposed so as to cover the circuit board 20.

  The circuit board 20 of the light source device 10 attached to the side wall of the optical box 30 is provided so as to protrude outside (outside) the optical box 30. For this reason, by providing the protective sheet 33 so as to cover the circuit board 20, when the optical scanning device 100 is placed, when the optical scanning device is assembled and adjusted, during transportation, and when the optical scanning device is incorporated into the image forming apparatus. For example, the semiconductor laser 11 and the variable resistors 22 and 23 can be protected.

The protective sheet 33 shown in the present embodiment is a thin plastic sheet (film-like sheet member) having a thickness of about 20 μm, and has a surface resistance value of 1 × 10 ^{11 to} 9 × 10 ¹² Ω. It is a sheet having characteristics.

  Since electrical elements such as the semiconductor laser 11 and the control IC 21 may be damaged by excessive static electricity, it is not possible to use a plastic sheet that easily retains excessive static electricity due to peeling charging or frictional charging as a protective sheet for the circuit board. It is not preferable.

  Since the protective sheet 33 of this embodiment has antistatic properties, it is possible to prevent electrical elements such as the semiconductor laser 11 and the control IC 21 from being damaged by excessive static electricity.

  Further, since the protective sheet 33 is a member disposed near an electric element that is likely to generate heat when an abnormality occurs, it may be a sheet member that has self-extinguishing properties and excellent flame retardancy. preferable.

  Furthermore, the protective sheet 33 of this embodiment also has a role as a dustproof sheet that prevents dust from entering the optical scanning device through a slight gap around the light source device 10.

  Here, if dust adheres to a rotating polygon mirror, lens, or reflecting mirror that rotates at high speed, the amount of laser light on the photoreceptor decreases, resulting in a decrease in print image density and density unevenness. Is concerned.

  Therefore, the opening of the optical box 30 and the opening for the bundled wire opened in the cover member 31 are closed using a sheet material, urethane foam 53, 54, or the like.

  Moreover, in the light source device 10, it is attached to the fitting hole 30b as an attaching part provided in the side wall 30a of the optical box 30, and is fixed to the optical box by screws (not shown). Here, when it is difficult to arrange many ribs etc. around the fitting hole 30b to which the light source device 10 is attached, and it becomes difficult to sufficiently secure the strength of the side wall 30a of the optical box 30. There is. Since the upper portion of the optical box 30 is covered with the cover member 31, in such a case, a slight gap is generated between the optical box 30 and the cover member 31.

  Therefore, the present embodiment is characterized in that the protective sheet 33 is extended and a part of the protective sheet 33 is overlapped and attached.

  In the present embodiment, as shown in FIG. 1, the protective sheet 33 is a gap between the optical box 30 and the cover member 31 in the vicinity of the fitting hole 30 b of the side wall 30 a of the optical box 30 (upward in FIGS. 1 and 2). It is provided so as to cover. Thereby, since the slight clearance gap between the fitting hole 30b optical box 30 and the cover member 31, and the slight clearance gap between the fitting hole 30b and the light source device 10 can be plugged up, improvement in dustproof performance can be achieved. It can be realized.

  Here, in this embodiment, the protective sheet 33 is attached to the cover member 31 with the tape 34. However, the means for attaching the protective sheet 33 to the cover member 31 is not limited to this, and may be, for example, by adhesion. Further, in the present embodiment, the protective sheet 33 has a shape that is bent to an L-shaped section with a strong material, and therefore does not particularly fix the circuit board side. However, the circuit board side may be affixed with double-sided tape, or the protective sheet may be folded and hooked onto the circuit board. Applicable.

  As described above, according to this embodiment, it is possible to prevent fluctuations in the amount of laser light by preventing contact with the variable resistors 22 and 23 on the circuit board 20. Furthermore, since it is possible to prevent minute dust from entering through a fitting portion to which the light source device 10 is attached and a slight gap between the optical box 30 and the cover member 31, It is possible to prevent contamination of optical members such as lenses.

  Here, in the present embodiment, the protective sheet 33 is provided so as to cover the gap between the optical box 30 and the cover member 31 in the vicinity of the fitting hole 30b of the side wall 30a of the optical box 30. It is not limited. The protective sheet 33 only needs to be extended to the cover member 31 so as to close a slight gap generated between the optical box 30 and the cover member 31 according to the specifications of the optical scanning device.

  In the present embodiment, the protective sheet 33 is provided so as to substantially cover the entire circuit board 20 with respect to the circuit board 20, but is not limited thereto. If the protective sheet 33 is provided so as to cover at least the variable resistors 22 and 23 of the circuit board 20, the protection sheet 33 can prevent contact with the variable resistors 22 and 23 on the circuit board 20, and prevent fluctuations in the laser light quantity. be able to.

  FIG. 3 is a diagram illustrating a modified example of the protective sheet.

  The protective sheet 35 shown in FIG. 3 is a protective sheet having a notch-shaped portion 35a in which a part of the sheet member corresponding to the variable resistors 22 and 23 is partially cut out.

  By using such a protective sheet 35, when it becomes necessary to adjust the variable resistors 22 and 23 again, the positions of the variable resistors 22 and 23 can be easily specified, and workability is further improved.

  Moreover, the same effect can be acquired when the protective sheet 35 is used by comprising the protective sheet 33 mentioned above by a transparent or translucent sheet | seat member.

  Embodiment 2 of the present invention will be described below.

  In this embodiment, the circuit board 20 is covered with a protective cover 37 made of nonconductive plastic instead of the antistatic protective sheet 33 described in the first embodiment as a protective member.

  FIG. 4 is a schematic perspective view showing a portion where the protective cover 37 is attached in the optical scanning device 100 of the present embodiment. In the present embodiment, the different components from the first embodiment will be described, and the description of the same components as those in the first embodiment will be omitted.

  In Example 1, in order to prevent the film-like protective sheet from holding excessive static electricity due to peeling charging, frictional charging, or the like, and damaging the electrical components such as the semiconductor laser 11 and the control IC 21, charging is performed in the first embodiment. A protective sheet having a prevention function is used.

  On the other hand, in this embodiment, a protective cover 37 formed of plastic is used. Since the protective cover formed of plastic is difficult to retain excessive static electricity, when the protective cover is formed of plastic, a plastic material having antistatic properties is not necessarily required.

  However, it is more preferable that the protective cover 37 is made of a plastic material that is difficult to be charged, because the plastic that is easily charged is liable to be adhered to floating thread-like flakes and the like. Furthermore, since the protective cover 37 is disposed in the vicinity of an electric element that is likely to generate heat when an abnormality occurs, the protective cover 37 is preferably made of a flame retardant material.

  In this embodiment, a high-rigidity protective cover 37 formed of such a plastic material is used.

  The protective cover 37 is provided so as to cover the variable resistors 22, 23 and the like on the circuit board 20 when the engaging portion 37 a is engaged and held with the mounting portion 36 a of the optical box 36. Further, the upper surface of the protective cover 37 extends to the cover member 31 of the optical scanning device 100, and a hole 37 b provided on the upper surface of the protective cover 37 is formed with a resin rivet (fixing member) 38 on the upper surface of the cover member 31. It is fixed using. Here, the fixing of the protective cover 37 is not limited to the resin rivet 38, and a retaining ring or the like may be used as a fixing member. Further, the engaging part 37a and the hole 37b constitute a first fixing part and a second fixing part, respectively.

  Here, when the circuit board 20 is protected using a highly rigid protective cover, the circuit board 20 may be stressed due to warping or deformation of the highly rigid protective cover. When stress is applied to the circuit board 20, there is a concern that a contact failure of the electric element or a laser beam irradiation position shift may occur.

  Since the protective cover 37 of the present embodiment is fixed to the optical box 36 and the cover member 31, it is possible to prevent the circuit board 20 from being stressed by warping or deformation of the protective cover 37.

  FIG. 5 is a view showing a modified example using a non-conductive plastic protective cover 39, and the left end of the protective cover 39 can be rotated to the mounting portion 36a of the optical box 36 as in the second embodiment. An engaging portion 39a is provided for engaging with. After the engaging portion 39a is assembled to the mounting portion 36a of the optical box 36, the protective cover 39 is rotated in the direction of the arrow. At this time, the protective cover 39 is attached to the optical box 36 by engaging the snap-fit portion 39 b provided at the right end of the protective cover 39 with the rib-shaped support portion 36 b provided on the side surface of the optical box 36.

  The protective cover 39 covers the variable resistors 22 and 23 on the circuit board 20 and extends to a cover member (not shown). Further, when it becomes necessary to readjust the variable resistors 22 and 23, the snap-fit portion 39b can be easily removed, and even if the protective cover 39 is warped or deformed, the circuit board 20 or optical It is possible to prevent the box 36 from being stressed.

  Such a protective cover that suppresses the displacement of the irradiation position of the laser beam is more suitable for a color image forming apparatus that forms an image with a plurality of laser beams.

1 is a perspective view illustrating a schematic configuration of an optical scanning device according to Embodiment 1. FIG. FIG. 2 is a perspective view illustrating a schematic configuration of the optical scanning device according to the first embodiment, and illustrates a state in which a cover member is removed with respect to FIG. 1. It is a figure which shows the modification of a protective sheet in Example 1. FIG. In the optical scanning device of Example 2, it is a schematic perspective view which shows the part to which the protective cover was attached. In Example 2, it is a figure which shows the modification of a protective cover. It is a schematic sectional drawing which shows an image forming apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Light source device 11 Semiconductor laser 20 Circuit board 22, 23 Variable resistance 30 Optical box 31 Cover member 33 Protection sheet 100 Optical scanning device

Claims (4)

A light source that emits laser light,
A variable resistor for adjusting the amount of laser light emitted by the light source, and
A circuit board on which the variable resistor is mounted and drives the light source;
A light source unit having
An optical box to which the light source unit is attached;
A lid member for closing the optical box;
An optical scanning device in which the circuit board is disposed outside the optical box,
A protective member that covers at least the variable resistor of the circuit board and covers a gap between the optical box and the lid member in the vicinity of an attachment portion of the optical box to which the light source unit is attached. Optical scanning device.   The optical scanning device according to claim 1, wherein the protection member is made of a non-conductive material. The optical scanning device according to claim 2, wherein the protective member is a sheet member having a surface resistance value of 1 × 10 ^{11 to} 9 × 10 ¹² Ω.   3. The optical device according to claim 1, wherein the protection member is formed of a plastic material and includes a first fixing portion and a second fixing portion that are respectively fixed to the optical box and the lid member. Scanning device.

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