JP2000098287A - Optical scanner and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the dispersion of a noise while effectively discharging a heat from a polygon mirror driving motor, in the case of forming a tightly closed space near the polygon mirror in order to prevent and shield the noise generated from the driving motor in accordance with the increase of the rotating speed of the polygon mirror constituting the optical scanner. SOLUTION: The optical scanner is provided with a polygon scanner 4 equipped with a rotary polygon mirror 4a for deflecting laser light emitted from a light source, an optical housing 3 for supporting the polygon scanner, a side wall 5 erected in the optical housing so as to surround the polygon mirror, a transmission optical element 6 partly constituting the side wall and for transmitting the laser light deflected by the rotary polygon mirror to the outside of the side wall, a sheet-like cover 7 which is fixed to the upper end edge of the side wall so as to close the space in the side wall, an elastic sealing member 10 which is interposed between the upper end edge of the side wall and the sheet-like cover so as to tightly seal the gap, and holes 11 for partly exposing the sheet-like cover are formed for the elastic sealing member.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device and an improvement of an image forming apparatus using the optical scanning device. More specifically, the present invention relates to an increase in the rotation speed of a polygon mirror constituting the optical scanning device. An optical scanning device capable of effectively dissipating heat generated from a motor for driving a polygon mirror and preventing the diffusion of noise when a closed space is provided in the vicinity of the polygon mirror in order to prevent noise generated due to And an image forming apparatus.

[0002]

2. Description of the Related Art As an optical scanning device (optical writing device) used in an electrophotographic image forming apparatus such as a copying machine, a printer, and a plain paper facsimile machine, a polyhedral mirror (hereinafter, referred to as a polygon mirror) is rotated. Optical scanning systems that deflect laser light from a light source are widely used.
In recent years, the number of rotations of the polygon mirror has tended to increase in order to satisfy the demand for improving print productivity, and accordingly, an increase in noise has become a problem. In order to solve this problem, Japanese Patent Application Laid-Open No. Hei 9-105881 discloses a soundproofing structure in which the vicinity of a polygon mirror is formed as a substantially enclosed space. In the case where a mirror drive motor is provided, the resin material products (for example, fθ lens, etc.) around the polygon mirror are adversely affected by heat accumulation and temperature rise due to heat generated from the drive motor, and there is a problem in the performance and durability of the scanning device. Occurs. For this reason, it is necessary to radiate heat generated from the drive motor to the outside.In Japanese Patent Application Laid-Open No. 9-105881, the polygon mirror and the drive motor are hermetically sealed using a metal cover independent from the cover on the optical housing side. It has been proposed to dissipate heat from this cover. Further, in the technology described in this publication, a seal member for preventing dust from entering through a gap between the metal cover and the cover on the optical housing side is arranged. However, the shape of the cover that covers the mirror unit and the drive motor unit (hereinafter, collectively referred to as a polygon scanner) proposed here is complicated, and a manufacturing process such as casting and cutting is indispensable for manufacturing a metal cover. We could not avoid the rising costs. Also, the shape of the sealing member must be complicated in order to cope with the complicated cover shape, and it is difficult to ensure the sealing performance.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and has been made in order to prevent noise generated from a drive motor due to an increase in the number of rotations of a polygon mirror constituting an optical scanning device and to prevent noise. It is an object of the present invention to provide an optical scanning device and an image forming apparatus capable of effectively dissipating heat generated from a motor for driving a polygon mirror and preventing the diffusion of noise when the vicinity of the polygon mirror is a closed space. And

[0004]

In order to solve the above-mentioned problems,
According to a first aspect of the present invention, there is provided a polygon scanner provided with a rotating polygon mirror for deflecting a laser beam emitted from a light source, an optical housing for supporting the polygon scanner, and an upright standing on the optical housing so as to surround the polygon scanner. A side wall, a transmission type optical element that constitutes a part of the side wall and transmits laser light deflected by the rotary polygon mirror to the outside of the side wall,
An optical scanning device comprising: a plate-shaped cover fixed to an upper edge of a side wall to close a space in the side wall; and an elastic sealing member interposed between the upper edge of the side wall and the plate-shaped cover to seal a gap. Wherein the elastic seal member is provided with a hole for exposing a part of the plate-like cover.
The invention according to claim 2 is characterized in that the plate-shaped cover is made of a material having higher thermal conductivity than the optical housing and the side wall. The invention of claim 3 is characterized in that in claim 1 or 2, the plate-like cover is made of metal. According to a fourth aspect of the present invention, there is provided the optical scanning device according to any one of the first to third aspects.

According to the first aspect of the present invention, in order to solve the above-mentioned problem, a simple-shaped side wall surrounding the entire polygon scanner is erected around a housing portion to which the polygon scanner is attached, and an upper end of the side wall is provided. A plate-shaped cover is attached to the edge to close the space in the side wall. Further, a seal member formed by a simple punching die is attached to the lower surface of the plate-like cover, thereby substantially sealing the periphery of the polygon scanner. As a result, it is possible to obtain a sound insulating property equivalent to that of the related art while having a low-cost configuration. However, since a seal member made of foam rubber or the like generally has extremely poor heat conduction, heat is not radiated to the outside through the plate-shaped cover, and the heat radiation obtained by the conventional technology cannot be secured.
Therefore, in the present invention, the plate-shaped cover is removed by removing a portion where it is highly necessary to ensure the airtightness and sealing performance of the seal member, that is, the seal member portion excluding the portion where the upper edge of the side wall and the seal member are in contact. The plate-like cover was made of a material having a high thermal conductivity such as a metal. According to the second and third aspects of the present invention, a sufficient heat radiation effect can be obtained by selecting a material having a higher thermal conductivity than at least the optical housing as a material of the plate-shaped cover, and a considerable area of the plate-shaped cover can be obtained. By contacting with high-temperature air around the polygon scanner, the heat radiation effect can be enhanced. Also, when an optical scanning device having an insufficient heat dissipation structure is used for an image forming apparatus such as a laser printer,
Although the cost of the entire apparatus was increased by providing a dedicated cooling fan and the reliability was not reduced due to heat, according to the third aspect of the invention, the polygon scanner can be cooled with a low-cost configuration. A cooling structure that does not increase the cost of the image forming apparatus can be obtained.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 is a schematic sectional view of a laser printer using an optical scanning device (hereinafter, referred to as a writing unit) to which the present invention is applied. The writing unit 1 is installed inside the apparatus, and receives a photosensitive member 2 according to an image signal.
An image is formed by scanning a laser beam on the top. The photosensitive member 2 is uniformly charged in advance, and an electrostatic latent image is formed on the photosensitive member 2 by a laser beam emitted from the writing unit 1 to the charged surface. This electrostatic latent image is developed with toner supplied from the developing device 20 to become a toner image. This toner image is transferred onto transfer paper by the transfer device 21, and the transferred transfer paper is conveyed to the fixing device 22. After the toner image is fixed, the toner image is discharged outside the apparatus. Reference numeral 25 denotes a paper feeding device for supplying transfer paper.
The detailed operations and functions of the other parts are widely used as electrophotographic apparatuses and will not be described.
The present invention provides a sound insulation structure in the writing unit 1,
It is characteristic that the sound insulation and heat dissipation are improved at low cost by improving the heat dissipation structure.

FIG. 2 is a perspective view showing a configuration of a writing unit according to an embodiment of the present invention with a cover removed. A polygon scanner 4 is fixed at a predetermined position on an optical housing 3 made of resin by a polygon scanner fixing screw 12. Attached,
Side walls (convex ribs) 5 are integrally formed on the optical housing 3 so as to surround the entire periphery of the polygon scanner 4. The polygon scanner 4 has a polygon mirror (rotating polygon mirror) 4a and a drive motor 4b thereof. Side wall 5
Has a transmission type optical element 6 composed of a sound insulating glass plate or a lens in a part thereof. Although the main body of the side wall 5 is made of resin or the like, a continuous side wall is formed by arranging the transmission type optical element 6 in an opening part of which is partially removed. As will be described later, a metal plate-shaped cover is placed over the upper end edge of the side wall 5 including the transmission type optical element 6, and the space (including the polygon scanner 4) surrounded by the side wall 5 is closed.
In the above configuration, a laser beam emitted from a not-shown laser diode (not shown) is reflected by the polygon mirror 4a, and is imaged on the photoconductor 2 via each not-shown image forming element. A part of the side wall 5 surrounding the polygon scanner 4 has an opening through which a laser beam passes, and a transmission type optical element 6 such as a sound insulating glass is attached to this opening.

FIG. 3 is a perspective view showing a state in which a cover is attached to the writing unit of FIG. 2, and a cover 7 made of an iron plate formed by press working is provided above the polygon scanner 4 located inside the side wall 5. Are attached using screws 8. The optical elements excluding the polygon scanner 4 are covered with a resin cover 9. FIG. 4 is a bottom view of the cover, and FIG. 5 is a longitudinal sectional view of a main part of the optical housing closed by the cover. As shown in FIG. When the cover 7 made of iron plate is attached, the cover 7 is compressed and deformed by being pressed against the side wall 5 (including the sound insulating glass 6) of the optical housing, thereby increasing the hermeticity near the polygon scanner. A hole 11 is formed in the seal member 10 except for a position in contact with an upper edge of the side wall 5 and the sound insulating glass 6, so that the air near the polygon scanner and the cover 7 come into direct contact. This will be described in more detail. The portion indicated by the chain line in FIG. 4 indicates a range where the upper edge of the side wall 5 (including the sound insulating glass 6) is in contact, and the sealing member 10 covers a required range including the contact portion. While covering, the bottom surface of the cover
1 is in an exposed state. Seal member 1
The contact between the bottom surface of the cover and the upper edge of the side wall increases the airtightness, while the hole 11 is formed to expose the bottom surface of the cover, so that the polygon scanner surrounded by the side wall 5 and its periphery are formed. Before the air in the sealed space is overheated, heat can be radiated through the exposed cover bottom surface.

As described above, according to the present invention, a simple-shaped side wall 5 (including a transparent glass plate or a lens 6) surrounding the entire polygon scanner is provided around the portion of the optical housing to which the polygon scanner is attached. And a plate-shaped cover 7 is attached to the upper edge of the side wall 5 to close the space in the side wall. Furthermore, the periphery of the polygon scanner is substantially sealed by interposing a seal member 10 formed by a simple punching die between the lower surface of the plate-shaped cover and the upper edge of the side wall. As a result, it is possible to obtain a sound insulating property equivalent to that of the related art while having a low-cost configuration. However, since the seal member 10 generally made of foam rubber or the like has extremely poor heat conduction, heat is not radiated to the outside through the plate-shaped cover 7 and the heat radiation obtained by the conventional technique cannot be secured. Therefore, in the present invention, the plate-shaped cover is removed by removing a portion where it is highly necessary to ensure the airtightness and sealing performance of the seal member, that is, the seal member portion excluding the portion where the upper edge of the side wall and the seal member are in contact. The plate-like cover was made of a material having a high thermal conductivity such as a metal. By selecting a material having a higher thermal conductivity than at least the optical housing as the material of the plate-shaped cover, a sufficient heat radiation effect can be obtained.Moreover, a considerable area of the plate-shaped cover can be removed from the high-temperature air around the polygon scanner. The contact can enhance the heat radiation effect.

[0010] If a special material such as carbon graphite is used as a material having a high thermal conductivity, the cost cannot be avoided, but as long as a normal metal is used, it is possible to avoid the cost increase. Increase heat dissipation efficiency,
Damage caused by overheating around the polygon scanner can be avoided. In addition, when an optical scanning device having an insufficient heat radiation structure is used for an image forming apparatus such as a laser printer, the cost of the entire apparatus is increased, such as providing a dedicated cooling fan, and a decrease in reliability due to heat cannot be avoided. However, according to the present invention, since the cooling of the polygon scanner unit can be performed with a low-cost configuration, a cooling structure that does not increase the cost of the image forming apparatus can be obtained.

[0011]

As described above, in the optical scanning device according to the first aspect, the space formed by surrounding the polygon scanner with the side wall is closed by the plate-like cover, and the space is formed on the bottom surface of the plate-like cover. A hole that exposes a part of the plate-shaped cover is provided in the attached elastic seal member, so that contact between air near the polygon scanner and the plate-shaped cover can be ensured, and heat transfer to the plate-shaped cover and the plate The vicinity of the polygon scanner can be efficiently cooled by heat radiation from the cover. In the optical scanning device according to the second aspect, since the plate-shaped cover is made of a material having higher thermal conductivity than the optical housing, the effect of the first aspect can be more effectively obtained.
In the optical scanning device according to the third aspect, since the metal plate-shaped cover is used, the effects of the first and second aspects can be achieved without using a special material and processing (without increasing the cost). According to the image forming apparatus of the fourth aspect,
Since the optical scanning device described in the paragraphs 2 and 3 is used, the optical scanning device can be efficiently cooled, and the cost of the entire image forming apparatus can be prevented from increasing, and the reliability due to heat can be prevented from decreasing.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus to which an optical scanning device according to the present invention is applied.

FIG. 2 is a perspective view showing a state in which a cover of the optical scanning device according to one embodiment of the present invention is removed.

FIG. 3 is a perspective view showing a state in which a cover of the optical scanning device according to one embodiment of the present invention is attached.

FIG. 4 is a bottom view of the cover.

FIG. 5 is a sectional view of a main part of the optical scanning device with a cover attached.

[Explanation of symbols]

Reference Signs List 1 writing unit, 2 photoreceptor, 3 optical housing, 4 polygon scanner, 4a polygon mirror (rotating polygon mirror), 4b drive motor, 5 side wall, 6 transmission type optical element, 7 plate cover, 8 screw, 9 cover, 1
0 seal member, 11 holes, 20 developing device, 21 transfer device, 25 paper feeding device.

Claims (4)

[Claims] 1. A polygon scanner having a rotary polygon mirror for deflecting a laser beam emitted from a light source, an optical housing supporting the polygon scanner, and a side wall erected on the optical housing so as to surround the polygon scanner. A transmission type optical element which forms a part of the side wall and transmits the laser beam deflected by the rotating polygon mirror to the outside of the side wall; and a plate-like member which is fixed to an upper edge of the side wall to close a space in the side wall. An optical scanning device comprising: a cover; and an elastic seal member interposed between an upper edge of a side wall and the plate-shaped cover to seal a gap, wherein a part of the plate-shaped cover is exposed to the elastic seal member. An optical scanning device, wherein a hole for causing the light scanning device is provided. 2. The optical scanning device according to claim 1, wherein the plate-shaped cover is made of a material having higher thermal conductivity than the optical housing and the side wall. 3. The optical scanning device according to claim 1, wherein the plate-like cover is made of metal. 4. An image forming apparatus using the optical scanning device according to claim 1, 2, or 3.