JP2000267037A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the heat generation of the whole of an optical box with an inexpensive configuration. SOLUTION: A flow passage 44 closed so as to make a round of the outside circumference of a housing 21a is formed of the outside wall 37, the bottom wall and the inside wall 38 of the housing 21a, a transmission glass 14 and an upper cover. In order to extend surface area by making the passage 44 longer than the outside circumference, ribs 37a and 38a are respectively formed at one part sides of the walls 37 and 38 so as to form one part 44a of the passage 44 like a crank. Besides, a rotary polygon mirror and the driving part thereof are arranged in the passage 44 and other optical elements are arranged outside the passage 44. Then, an air flow produced by the rotation of the rotary polygon mirror is endlessly circulated along the inside of the passage 44, that means, along the outside circumference of the housing 21a.

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 that scans a light beam with a rotating polygon mirror, and more particularly to an optical scanning device characterized by a mechanism for reducing heat generation of the optical scanning device.

[0002]

2. Description of the Related Art FIG. 3 schematically shows a general optical scanning device. Light 20 emitted from a light source (not shown) is deflected by a rotating polygon mirror 11 rotated by a polygon motor 12, and transmitted glass 14, fθ mirror 19, folding mirror 15, toroidal lens 13, folding mirror 1
6. An image is formed on the photoreceptor 18 via the transmission glass 17.
In recent years, image forming apparatuses such as laser printers have been required to operate at higher speeds and have higher fineness. In order to satisfy these requirements, it is necessary to rotate the polygon motor 12 for driving the rotating polygon mirror at a higher speed.

Therefore, in the conventional example, in order to suppress the wind noise caused by the rotation of the rotary polygon mirror 11 and the adhesion of dirt such as dust to the rotary polygon mirror 11, as shown in FIG.
In the entire space of the optical box 21, only the vicinity of the rotary polygon mirror 11 is substantially sealed by the wall 33 and the bottom wall formed in 1, the transmission glass 14, a cover (not shown) covering the upper surface of the optical box 21, and the like. Often. Also, by not substantially sealing only the space near the rotary polygon mirror 11 but substantially sealing the entire optical box 21, not only the rotary polygon mirror 11 but also all optical elements arranged in the optical box 21 can be used. There is also known a structure in which dust does not adhere.

[0004]

However, if only the space in the vicinity of the rotary polygon mirror 11 is substantially sealed, the heat of the polygon motor 12 is trapped in the substantially sealed space, and the drive for driving the rotary polygon mirror 11 is performed. The temperature around the polygonal mirror 11 rises significantly due to heat generated by the ICs and the bearings of the polygonal mirror 11, thereby shortening the life of the polygonal mirror 11.
1 and the performance of the driving unit thereof is deteriorated.

Further, if the entire optical box 21 is substantially closed, there is a problem that the temperature of the imaging element rises due to the heat generated in the driving section of the rotary polygon mirror 11, and the beam does not form an image at a predetermined position. Particularly, in recent years, in order to reduce costs, a resinous optical element whose imaging characteristic varies greatly depending on the temperature is used, so this problem cannot be ignored. Therefore, if a heat sink, a fan, or the like is provided to solve this problem, the cost will increase. Also, the optical box 21 itself is often made of inexpensive resin instead of aluminum or the like.

As a conventional example of this kind, Japanese Patent Laid-Open No. Sho 62-144129 discloses a method of providing a ventilation path for guiding an air flow generated by the rotation of a rotary polygon mirror to a cooling section such as an internal semiconductor laser or an external fixing device. Gazette, Japanese Patent Laid-Open No. 9-265050
No. 1993. However, this method cannot reduce the heat generation of the entire optical box 21.
As another conventional example, Japanese Patent Application Laid-Open No. 10-20233 and Japanese Patent Application Laid-Open No. 10-20233 disclose a method of inducing dust so as not to adhere to an imaging lens by an air flow generated by rotation of a rotary polygon mirror.
In any case, it is proposed in Japanese Patent Application Laid-Open No. 186267, but it does not solve the problem of the heat generated by the optical box and the problems caused by the heat generated.

The present invention has been made in view of such a situation of the prior art, and has as its object to provide an optical scanning device capable of reducing heat generation of the entire optical box with an inexpensive configuration.

[0008]

According to a first aspect of the present invention, a light source, a rotary polygon mirror for deflecting a light beam of the light source and a driving unit thereof, and a light source for deflecting the deflected light beam are provided. In an optical scanning device in which an imaging element for forming an image at a position is accommodated in an optical box, a flow path for circulating an air flow generated by the rotating polygon mirror in the optical box is formed. .

The second means is characterized in that in the first means, the flow path is formed longer than the outer periphery of the optical box.

[0010] A third means is that, in the first and second means, the flow path is formed on an outer wall, a bottom wall and an inner wall of the optical box substantially parallel to the outer wall, and an upper opening of the outer wall and the inner wall. It is characterized by being formed by a cover for sealing.

A fourth means is that the flow path is longer than the outer circumference of the optical box and the surface area is increased by forming ribs on the outer and inner walls of the optical box in the first to third means. It is characterized by.

The fifth means is characterized in that in the first to fourth means, the optical box is formed of a resin.

The sixth means is characterized in that, in the fifth means, a part of the wall forming the flow path is formed of a member having higher rigidity and heat conductivity than the resin.

According to a seventh aspect, in the sixth aspect, the member having higher rigidity and heat conductivity than the resin is a metal plate for sealing upper openings of the outer wall and the inner wall of the optical box. I do.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an external view showing an embodiment of the optical scanning device according to the present invention.

In FIG. 1, the optical box 21 has a housing 21a whose upper part is open, and a cover (not shown) for closing the upper opening of the housing 21a. Holes for attaching to a member (not shown) supporting the optical box 21 are formed in the four corners of the housing 21a (36a, 36b, 36c and one place not shown in the figure).

An inner wall 38 substantially parallel to the outer wall 37 is formed in the housing 21a, and the transmission glass 14 shown in FIG. And the housing 2
1a, an outer wall 37, a bottom wall, and an inner wall 38;
And the upper cover, a closed flow path 44 is formed so as to go around the outer periphery of the housing 21a. In order to increase the surface area by making the flow path 44 longer than the outer circumference, ribs 37 are respectively provided on a part of the outer wall 37 and the inner wall 38.
a, 38a are formed, and a portion 44a of the flow path 44 is formed in a crank shape.

The rotary polygon mirror 11 and its driving section are arranged in the flow path 44, and another optical element shown in FIG. According to such a configuration,
The air flow generated by the rotation of the rotary polygon mirror 11 is
It circulates endlessly along the inside, that is, along the outer periphery of the housing 21a, whereby heat generation of the entire optical box 21 can be reduced with an inexpensive configuration.

If the housing 21a is made of a resin and the rigidity and the heat conductivity are insufficient, as shown in FIG. 2, one of the flow passages 44 formed in a crank shape by the ribs 37a and 38a. By sealing the upper opening of the portion 44a with the metal plate 43, the rigidity and thermal conductivity of the resin housing 21a can be enhanced.

[0020]

As described above, according to the first aspect of the present invention, since the flow path for circulating the air flow generated by the rotary polygon mirror in the optical box is formed, the optical system can be manufactured with a low-cost structure. Heat generation of the entire box can be reduced.

According to the second aspect of the present invention, since the flow path is formed longer than the outer periphery of the optical box, the heat generation of the entire optical box can be further reduced with an inexpensive configuration.

According to the third aspect of the present invention, the flow path is formed substantially parallel to the outer wall, the bottom wall, and the outer wall of the optical box;
Since the outer wall and the inner wall are formed by the cover for sealing, the heat generation of the entire optical box can be reduced with an inexpensive configuration.

According to the fourth aspect of the present invention, the ribs are formed on the outer and inner walls of the optical box, so that the flow path is longer than the outer circumference of the optical box and the surface area is increased. The overall heat generation can be further reduced.

According to the fifth aspect of the present invention, since the optical box is formed of resin, heat generation of the entire optical box can be reduced with an inexpensive configuration.

According to the sixth aspect of the present invention, since a part of the wall forming the flow path is formed of a member having higher rigidity and heat conductivity than resin, the optical box is formed of resin. Also, the heat generation of the entire optical box can be reduced.

According to the present invention, the member having higher rigidity and heat conductivity than the resin is a metal plate for sealing the outer wall and the inner wall of the optical box. Also, the heat generation of the entire optical box can be reduced.

[Brief description of the drawings]

FIG. 1 is an external view showing an embodiment of an optical scanning device according to the present invention.

FIG. 2 is an external view showing a modified example of the optical scanning device of FIG.

FIG. 3 is a configuration diagram schematically showing a general optical scanning device.

FIG. 4 is an external view showing a conventional optical scanning device.

[Explanation of symbols]

 21a Housing 37 Outer wall 37a, 38a Rib 38 Inner wall 43 Metal plate 44 Flow path

Claims (7)

[Claims] 1. An optical box comprising: a light source; a rotary polygon mirror for deflecting a light beam of the light source; a driving unit therefor; and an imaging element for forming an image of the deflected light beam at a predetermined position. An optical scanning device, wherein a flow path for circulating an air flow generated by the rotary polygon mirror in the optical box is formed in the scanning device. 2. The optical scanning device according to claim 1, wherein the flow path is formed longer than an outer circumference of the optical box. 3. The flow path is formed by an outer wall, a bottom wall of the optical box, an inner wall formed substantially parallel to the outer wall, and a cover for sealing an upper opening of the outer wall and the inner wall. 3. The optical scanning device according to claim 1, wherein: 4. By forming ribs on an outer wall and an inner wall of the optical box, the flow path is longer than an outer periphery of the optical box.
4. The optical scanning device according to claim 1, wherein a surface area is increased. 5. The optical scanning device according to claim 1, wherein the optical box is formed of a resin. 6. The optical scanning device according to claim 5, wherein a part of the wall forming the flow path is formed of a member having higher rigidity and heat conductivity than the resin. 7. The optical scanning device according to claim 6, wherein the member having higher rigidity and heat conductivity than the resin is a metal plate for sealing upper openings of an outer wall and an inner wall of the optical box. .