JP2002156595A - Optical scanner and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical scanner which is made effectively compact without adding a special part and also an image forming device provided with a compact optical scanner. SOLUTION: Since a light beam is detoured to an fθ lens 9 because scanning light emitted by a light deflector 8 is returned by mirrors 10 and 12 after passing through at least one scanning optical device 7, 9 or 11 and passes through a space between the light deflector 8 and the scanning optical device 9, a compact optical path is constituted so as to draw the numeral of four, so that the optical scanner 2 is miniaturized than heretofore. Also, the reduction of a cost, the enhancement of rigidity, the improvement of the space allowance of the other unit, the miniaturization of an entire image forming device 1 and the optimization of an inside structure are attained by miniaturization thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a laser printer, a laser facsimile, and a digital copying machine, and an optical scanning device used for the same.

[0002]

2. Description of the Related Art In recent years, digitalization of an image apparatus has been advanced, and an apparatus using an electrophotographic process generally writes a laser beam deflected from an optical scanning apparatus onto a photosensitive member. Due to recent demands for space saving and miniaturization, the optical scanning device inside the image apparatus also tends to be miniaturized. In reducing the size of the optical scanning device, it is common practice to fold the optical path of the light beam using a folding mirror.

FIG. 5 is a diagram showing an example of a conventional optical scanning device used for an image forming apparatus. The upper figure is a plan view, and the lower figure is a side view drawn for a typical cross section. As shown in FIG. 5, the optical scanning device 2 located inside the image forming apparatus 1 includes an optical box 3 for placing an optical element at a predetermined position,
The optical box 3 is made up of a cover 4, which functions as a dust-proof and sound-insulating device to block the inside of the optical box 3 from the outside, a polygon motor 5, a laser oscillation unit 6, and a plurality of optical elements. The light beam emitted from the laser oscillation unit 6 is applied to a cylinder lens 7
Through the polygon mirror 8. After the light beam reflected by the polygon mirror 8 passes through the fθ lens 9, it is turned back by the first mirror 10 in the opposite direction, passes through the long lens 11, and is turned down by the second mirror 12. The light beam is then guided through the dustproof glass 13 onto the photoreceptor 14. With the rotation of the polygon mirror 8, the beam scans the photoconductor surface in a straight line to form an electrostatic latent image, and an image is formed through an image forming process.

FIG. 6 is a diagram showing an example of a conventional optical scanning device used for a color image forming apparatus. A color image is formed by superimposing four toner images of black, magenta, yellow, and cyan. In addition to the example of FIG. 5, a photoreceptor 18 is provided on the right side of the photoreceptor 14, and there is a corresponding optical path of the second light beam.
There are two optical paths. The light beam on the second optical path passes through the long lens 15, the mirror 16, and the dust-proof glass 17, and reaches the photosensitive member 18 on the right side. First, an electrostatic latent image is formed on the photoconductor 14 by the first light beam, and a toner image is formed by the black developing unit 19. An electrostatic latent image is formed on the photoreceptor 18 by the second light beam at a predetermined interval, and a magenta toner image is formed by the magenta developing unit 20. These two toner images are transferred onto the intermediate transfer belt 21 so as to be aligned. Next, a yellow electrostatic latent image is formed on the photosensitive member 14 again by the first light beam, and a toner image is formed in the yellow developing unit 22. Similarly, a cyan toner image is formed on the photoreceptor 18 by the second light beam at a predetermined interval from the cyan developing unit 23. The intermediate transfer belt makes one rotation after the previous process, and the toner images of these two colors are superimposed and transferred on the two colors previously transferred. The color image formed in this manner is transferred to transfer paper in the secondary transfer section 24, and a hard copy is obtained.

In this example, the fθ lens 9 is located directly above the photoreceptor 14, and the position of the optical scanning device 2 is in the leftward direction with respect to the image forming section composed of the photoreceptors 14, 18 and the intermediate transfer belt 21. Offset to Therefore, the optical scanning device 2 hinders miniaturization of the entire image forming apparatus and optimization of the internal structure.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical scanning device which is effectively compact without adding any special parts. Further, the present invention provides a compact optical scanning device applicable to a color machine, a two-color machine, and the like. Still another object of the present invention is to provide an optical scanning device in which a scanning optical element is functionally arranged. It is another object of the present invention to provide an image forming apparatus including a compact optical scanning device.

[0007]

According to a first aspect of the present invention, there is provided an optical deflector, at least one optical element, and scanning light scanned by the optical deflector. An optical scanning device having a mirror for guiding light to a scanning medium, wherein the scanning light emitted from the optical deflector passes through at least one optical element and is then turned back by the mirror, and the optical deflector, the optical element, An optical scanning device that passes between The invention described in claim 2 is
The optical scanning device according to claim 1, wherein there are a plurality of scanning light exits from the optical scanning device, and an optical element on which scanning light that has passed through the optical deflector first enters is between the plurality of exits. Optical scanning device located at According to a third aspect of the present invention, in the optical scanning device according to the first aspect, an optical element having a refractive power is disposed behind at least two of the mirrors, and a mounting direction of the optical element is:
The optical scanning device is substantially parallel to a plane including a light beam deflected by the optical deflector. According to a fourth aspect of the present invention, in the optical scanning device according to the first aspect, the surface on which the scanning optical element is mounted is a surface facing the surface on which the optical deflector is mounted. I do.

According to a fifth aspect of the present invention, there is provided the optical scanning device according to any one of the first to fourth aspects, wherein the charging device for charging the medium to be scanned contacts the charging member with the medium to be scanned. Then, the image forming apparatus is a charging device that performs charging by applying a voltage to the charging member. According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising the optical scanning device according to any one of the first to fourth aspects, wherein an alternating electric field is applied when a latent image on the medium to be scanned is developed. .

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing the configuration of an embodiment of the optical scanning device of the present invention. The above figure is a plan view,
The lower figure is a side view drawn for a representative cross section.

As shown in FIG. 1, a light beam emitted from a laser oscillation unit 6 passes through a cylinder lens 7 which is one of the optical elements, and is passed through an optical polarizer (hereinafter, referred to as a "polygon mirror") 8. The light beam deflected by the polygon mirror 8 and passed through the fθ lens 9, which is one of the optical elements, is bent upward at an acute angle by the first mirror 10, and becomes a long lens, which is one of the optical elements. After passing through 11, it is guided downward by the second mirror 12. The light beam passes between the polygon mirror 8 and the fθ lens 9, passes through the dustproof glass 13, and then reaches a medium to be scanned (hereinafter, referred to as “photoconductor”) 14. In this way, the light beam goes around the fθ lens 9 and the compact optical path is configured so as to draw a four-shape, so that the optical scanning device 2 can be made smaller than before. By downsizing, it is possible to reduce costs, increase rigidity, improve the space allowance of other units, downsize the entire image forming apparatus, and optimize the internal structure.

FIG. 2 is a diagram showing the configuration of an embodiment of an optical scanning device used in a color image forming apparatus when there are two photosensitive members. The optical path to the photoconductor 14 on the left is shown in FIG.
As in the case of the first embodiment, the light passes between the polygon mirror 8 and the fθ lens 9 and then passes through the dustproof glass 13. lens 9 is located between the two photoconductors 14 and 18. Therefore, the optical scanning device 2 is disposed above the two photoconductors 14 and 18 with a better balance than in the example of FIG. 3, so that the entire image forming apparatus can be reduced in size and the internal structure can be optimized.

Another embodiment is shown in FIG. Using three folding mirrors, the first mirror 10 and the second mirror 12 are arranged at a right angle to form a roof mirror configuration. The light beam is turned up by the first mirror 10 and then the second mirror 12
, And becomes horizontal again, and passes through the long lens 11. Thereafter, the light is folded toward the photoconductor 14 by the third mirror 25, and reaches the photoconductor 14 through the dustproof glass 13. In this example, since the long lens 11 can be arranged horizontally, the design of the arrangement surface of the long lens 11 and the mounting / adjusting method become easy. In addition, if the right angle between the first mirror 10 and the second mirror 12 is kept accurate by the roof mirror configuration, the level of the light beam passing through the long lens 11 can be easily maintained.

FIG. 4 shows still another embodiment. In this example, the optical scanning device 2 is arranged below the photoconductor 14. The light beam is turned downward by the first mirror 10, then turned horizontally again by the second mirror 12, and passes through the long lens 11. Thereafter, the light is folded back toward the upper photoconductor 14 by the third mirror 25, and reaches the photoconductor 14 through the dustproof glass 13. lens 9 is mounted so as to be hung on the lens mounting portion 26. The lens mounting section 26 has legs (not shown) and is installed in the optical box 3. As a result, f
The mounting surface of the θ lens 9 is a surface facing the mounting surface of the polygon motor 5 and is mounted in a suspended state.

As described above, the fθ lens 9 is suspended and mounted, and it is not necessary to provide the lens mounting portion 26 inside the optical path. The use of the optical scanning device 2 allows the lens mounting section 26 to have a larger cross-sectional area than when the lens mounting section 26 is provided inside the optical path. Further, in the image forming apparatus 1 using such an optical scanning device 2, since the design margin of the image forming apparatus 1 can be provided, it is advantageous in strength and vibration resistance, and forms a high quality image. be able to.

[0015]

As described above, in the optical scanning device according to the first aspect, the scanning light emitted from the optical deflector passes through at least one scanning optical element, is then turned back by the mirror, and is deflected by the light. Since the light beam passes between the scanning device and the scanning optical element, the light beam goes around the fθ lens, and a compact optical path is formed so as to draw a four-character. Thus, the optical scanning device can be made smaller than before. In the optical scanning device according to claim 2, when there are a plurality of photoconductors, the first scanning optical element on which the scanning light that has passed through the optical deflector first enters is located between the plurality of emission ports. The optical scanning device is arranged above the plurality of photoconductors in a well-balanced manner, and can reduce the size of the entire image forming apparatus and optimize the internal structure. Furthermore, in the optical scanning device according to the third aspect, the mounting direction of the optical element disposed behind the mirror is substantially parallel to the plane including the light beam deflected by the optical deflector. The design of the arrangement surface of the element and the mounting and adjustment method are facilitated. In the optical scanning device according to the fourth aspect, since the surface on which the scanning optical element is mounted is a downward surface, that is, a surface facing the surface on which the optical deflector is mounted, it is necessary to provide a mounting portion inside the optical path. In addition, it is possible to arrange an optical element having a high degree of freedom with less space restrictions. Further, the cross-sectional area of the optical element mounting portion can be made large, which is advantageous in terms of strength and vibration resistance, and enables formation of a high-quality image. In the image forming apparatus according to the fifth aspect, by providing the optical scanning device according to the first to fourth aspects, the size is reduced, the cost is reduced, the rigidity is increased, the space margin of other units is improved, and the entire image forming apparatus is improved. It is possible to reduce the size and optimize the internal structure. Further, the size of the entire image forming apparatus can be reduced by the charging device to be brought into contact. In the image forming apparatus according to the sixth aspect, the first to fourth aspects are described.
By providing the optical scanning device, it is possible to provide a margin in design of the image forming apparatus, which is advantageous in strength and vibration resistance, and can provide an image forming apparatus for forming a high quality image.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an embodiment of an optical scanning device.

FIG. 2 is a diagram illustrating a configuration of an embodiment of an optical scanning device used in a color image forming apparatus when there are two photoconductors.

FIG. 3 is a diagram showing another embodiment of the optical scanning device.

FIG. 4 is a diagram showing another embodiment of the optical scanning device.

FIG. 5 is a diagram illustrating an example of a conventional optical scanning device used for an image forming apparatus.

FIG. 6 is a diagram illustrating an example of a conventional optical scanning device used for a color image forming apparatus.

[Explanation of symbols]

 Reference Signs List 1 image forming apparatus 2 optical scanning device 3 optical box 4 cover 5 polygon motor 6 laser oscillation unit 7 cylinder lens (optical element) 8 polygon mirror (optical polarizer) 9 fθ lens (optical element) 10 first mirror 11, 15 long Length lens (optical element) 12, 16 Second mirror 13, 17 Dust-proof glass 14, 18 Photoconductor (medium to be scanned) 19 Black developing unit 20 Magenta developing unit 21 Intermediate transfer belt 22 Yellow developing unit 23 Cyan developing unit 24 Secondary Transfer unit 25 Third mirror 26 Mounting unit

Continued on front page F-term (reference) 2C362 BA51 BA56 BA85 BA86 BA87 BA90 CB80 DA03 DA06 DA07 2H045 AA01 BA34 CA63 DA02 DA04 DA44 5C072 AA03 AA05 CA06 DA04 HA02 HA06 HA13 QA14 XA01 XA05

Claims (6)

[Claims] 1. An optical scanning device comprising an optical deflector, at least one optical element, and a mirror for guiding scanning light scanned by the optical deflector to a medium to be scanned, wherein the light is emitted from the optical deflector. An optical scanning device, wherein the scanning light is returned by the mirror after passing through at least one optical element, and passes between the optical deflector and the optical element. 2. The optical scanning device according to claim 1, wherein there are a plurality of scanning light emission ports from the optical scanning device, and the plurality of optical elements on which the scanning light that has passed through the optical deflector first enters. An optical scanning device, wherein the optical scanning device is located between the emission ports. 3. The optical scanning device according to claim 1, wherein an optical element having a refractive power is disposed behind at least two of the mirrors, and a mounting direction of the optical element is deflected by the optical deflector. An optical scanning device which is substantially parallel to a plane including the light beam. 4. The optical scanning device according to claim 1, wherein the surface on which the scanning optical element is mounted is a surface facing the surface on which the optical deflector is mounted. . 5. A charging device equipped with the optical scanning device according to claim 1, wherein the charging device for charging the medium to be scanned contacts the charging member with the medium to be scanned, and a voltage is applied to the charging member. An image forming apparatus characterized in that the image forming apparatus is a charging device that performs charging by applying a voltage. 6. An image forming apparatus comprising the optical scanning device according to claim 1, wherein an alternating electric field is applied when developing a latent image on the medium to be scanned.