JP2001264655A - Optical scanner and color image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical scanner which makes the speeding-up, the miniaturization and cost reduction realize. SOLUTION: The optical scanner 10 performs the deflection scanning of laser beams AY, AM, AC and AK being made incident on a subscanning direction at a different angle by a polygon mirror 20, after passing through scanning lenses 22 and 22', turns up it to a photoreceptor 32 by reflecting mirrors 24, 24', and 26, 28 and 30. Here, the 28M and the 28C which constitute an optical path from the reflecting mirrors 24 and 24' to the photoreceptors 32M and 32C among the reflecting mirrors 26, 28 and 30, are disposed so that it may not lap with the optical path which the reflecting mirrors 26Y and 26K on the optical path from the reflecting mirror 24 and 24' to Photoreceptors 32Y and 32K, the reflecting mirrors 28Y and 28K, 30Y and 30K constitute when seeing from a subscanning direction. The optical path can be arranged without taking the mutual optical path interference into consideration for this reason, and, therefore, the height size of the optical scanner 10 can be minimized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single optical deflector and a plurality of scanning optical systems disposed on both sides of the single optical deflector are housed in a single housing, and a plurality of light beams are scanned on both sides of the optical deflector. Optical scanning device that simultaneously exposes a plurality of photoconductors, in particular, the size of the scanning optical system in the housing is reduced by making the return optical path a specific turn, and furthermore, the degree of freedom of the relative position with respect to the photoconductor is increased. It relates to the raised optical scanning device. The invention also relates to a color image forming apparatus equipped with the optical scanning device.

[0002]

2. Description of the Related Art Conventionally, an electrostatic latent image is formed by scanning and exposing a light beam modulated according to image information on a charged photoreceptor, and the image is formed by an electrophotographic process of development, transfer and fixing. Digital copiers and printers obtained are widely used.

Similarly, image signals corresponding to yellow (Y), magenta (M), cyan (C), and black (K) are charged, exposed and developed, and these are superimposed and transferred to form a full-color image. Full-color copying machines and color printers for forming images are also widely used.

Many of such full-color image forming apparatuses include a plurality of developing units corresponding to a plurality of colors (Y, M, C, and K) in a rotary developing apparatus, and a developing apparatus for each color image forming process. Are rotated to form developed images of different colors, and they are superimposed and transferred (hereinafter, referred to as a 4-cycle method).

However, in this four-cycle system, the process is repeated four times in order to obtain a full-color image, so that there is a disadvantage that the productivity is reduced to one-fourth or less as compared with the formation of a monochromatic (monochrome) image.

Therefore, a so-called tandem type image forming apparatus has been devised in which image forming apparatuses corresponding to respective developing colors are arranged in series and transfer images are sequentially superposed to form a full-color image in one pass.

FIG. 9 shows a conventional full-color image forming apparatus employing a tandem system. By adopting the tandem system as shown, the productivity of full-color images becomes equivalent to that of a monochrome machine. However, since the same number of image forming apparatuses ((Y), (M), (C), and (K)) as the number of developing colors are provided, the entire apparatus becomes large and costs increase. For this reason, at present, it is not widely used in general offices, which are the largest markets for full-color image forming apparatuses.

FIG. 10 shows a schematic configuration of a monochrome digital multifunction peripheral widely used in general offices.
The features will be described.

A digital MFP 110 illustrated in FIG.
Has a copying function, a printer function, a facsimile function, and the like. An image reading unit 112 is provided at the top of the apparatus. A cassette unit 114 is provided (four-stage configuration in the figure).

The height of the document table 116 of the image reading section is generally less than 1000 mm from the viewpoint of operability.
It is desirable to make the width direction as small as possible in order to reduce the installation area.
A little over 0 mm is a common value. Further, in order not to occupy both sides of the apparatus, a paper discharge tray unit 118 is often provided between the image reading unit 112 and the image forming unit 120.

As described above, in office use, there are restrictions on the size of the apparatus and the layout of each unit, so that the space that can be used by the image forming unit is limited. Therefore, in the tandem system (see FIG. 9), as described above, the size of the device is large, so that it is difficult to use it in an office.

On the other hand, in the conventional four-cycle type color machine, as the colorization of the document progresses and the ratio increases, the problem of the printing speed becomes more serious.

Therefore, there is a strong demand for a high-speed full-color image forming apparatus usable in an office.

[0014]

SUMMARY OF THE INVENTION In view of the above fact, it is a first object of the present invention to provide an optical scanning device which realizes high-speed, small-size, and low-cost full-color image forming apparatuses. It is a second object of the present invention to provide an optical scanning device that enhances the degree of freedom of the relative positional relationship between the photosensitive member and the optical scanning device in the full-color image forming device and promotes the miniaturization of the full-color image forming device.

[0015]

According to a first aspect of the present invention, there is provided an optical scanning device which deflects and scans each light beam incident from a plurality of light sources at different angles in a sub-scanning direction. A single rotating polygonal mirror, a common imaging optical system for imaging each light beam deflected at an angle in the sub-scanning direction by the single rotating polygonal mirror on a corresponding surface to be scanned, and A common reflecting mirror that reflects each light beam that has passed through a common imaging optical system toward the single rotating polygon mirror, and applies each light beam reflected by the common reflecting mirror to the respective scanned surface. Multiple folding mirrors,
A plurality of light sources, the single rotating polygon mirror, the common imaging optical system, the common reflection mirror, and an optical scanning device including a housing that houses the plurality of folding mirrors. Wherein at least one optical path among a plurality of optical paths from the common reflection mirror to the surface to be scanned has two or more return mirrors on an optical path from the common reflection mirror to the surface to be scanned; Of the folding mirrors, a folding mirror forming an optical path from the common reflection mirror to one surface to be scanned is formed by the two or more folding mirrors on an optical path from the common reflection mirror to another surface to be scanned. It does not overlap with the optical path in the sub-scanning direction.

According to a first aspect of the present invention, light beams emitted from a plurality of light sources are incident on a single rotating polygonal mirror provided in a single housing at different angles in the sub-scanning direction to perform deflection scanning. I do. Therefore, each light beam is deflected with an angle difference in the sub-scanning direction. Each of the deflected light beams passes through a common imaging optical system, enters a common reflecting mirror, is reflected toward the rotating polygon mirror, is reflected by a plurality of folding mirrors, and returns to the respective surfaces to be scanned. Be guided. At this time, the images are simultaneously formed on the corresponding surfaces to be scanned by the common imaging optical system.

Here, in a plurality of optical paths from the common reflecting mirror to the surface to be scanned, at least one of the optical paths includes at least two folding mirrors on the optical path from the common reflecting mirror to the surface to be scanned. Is arranged,
Of the plurality of folding mirrors, a folding mirror that forms an optical path from a common reflecting mirror to one surface to be scanned is composed of two or more folding mirrors on an optical path from the common reflecting mirror to another surface to be scanned. In the sub-scanning direction so as not to overlap the optical path of the light beam.

Thus, the range in which the optical path from the common reflecting mirror to one surface to be scanned and the optical path to the other surface to be scanned overlap in the sub-scanning direction is from the common reflecting mirror to the first turning mirror. The optical paths do not overlap after being turned by the first turning mirror.

Therefore, the housing for accommodating the common reflecting mirror and the plurality of folding mirrors can be reduced in the sub-scanning direction (height direction), and the size can be reduced.

Further, since each light beam is simultaneously deflected by a single rotating polygonal mirror and simultaneously scans each surface to be scanned, the speed can be increased as compared with the conventional four-cycle system.

In addition, since there is only one rotating polygon mirror and the image forming optical system and the reflecting mirror are common to each light beam, the number of parts is reduced, which contributes to downsizing of the apparatus.
Significant cost reduction compared to the conventional tandem system.

The common reflecting mirror according to the first aspect of the present invention may be arranged near the side end in the housing as in the second aspect. The common reflecting mirror in the present invention may be constituted by a plurality of adjacent reflecting mirrors.

Further, according to any one of the first to third aspects of the present invention, as in the fourth aspect, a common imaging optical system, a common reflecting mirror, and a plurality of folding mirrors are provided. The present invention is applied to a full-color optical scanning device which is disposed on both sides of a rotation axis of a single rotating polygon mirror and deflects and scans each light beam emitted from a plurality of light sources to both sides of the rotating polygon mirror. Is also good.

According to a fifth aspect of the present invention, there is provided a single rotating polygon mirror for deflecting and scanning each light beam incident from a plurality of light sources at different angles in the sub-scanning direction, and the single rotating polygon mirror. A common imaging optical system that forms each light beam deflected with an angle difference in the sub-scanning direction on a corresponding scan surface, and the single light beam that has passed through the imaging optical system is converted into the single light beam. A common reflecting mirror that reflects toward the rotating polygon mirror,
A plurality of return mirrors for returning each light beam reflected by the common reflection mirror to the respective scanned surface, the common imaging optical system, the common reflection mirror, and the plurality of Folding mirrors are disposed on both sides of the rotation axis of the single rotating polygon mirror, and each light beam emitted from each of the plurality of light sources is deflected and scanned on both sides of the rotating polygon mirror. In the optical scanning device provided with a housing for accommodating, the optical path length from the rotary polygon mirror of each of the light beams to the surface to be scanned is the same, and the optical path from the rotary polygon mirror to the final turning mirror is a rotary polygon mirror. It is characterized by being constructed asymmetrically with respect to the rotation axis.

According to a fifth aspect of the present invention, the size of the image forming apparatus is reduced by changing the relative positional relationship between the photosensitive member constituting the surface to be scanned and the optical scanning device. Normally, the exposure point on the photoreceptor (light beam incident position)
Is determined by the electrophotographic process design of charging, exposure, development and transfer, and the light beam emitted from the optical scanning device is often angled in one direction. In such a form, the area formed by the plurality of photoconductor units and the position of the optical scanning device are shifted from each other in the optical axis direction, which hinders downsizing of the image forming apparatus.

On the other hand, if the relative position between the optical scanning device and the photosensitive unit can be changed, the image forming apparatus can be mounted at a high density, and the apparatus can be downsized. However, the optical path of each light beam is limited by the optical path length from the light beam emission position to the photoconductor, and the optical scanning device is moved by changing the optical path folding in the housing without changing the final folding mirror position. There must be.

Therefore, while the optical path length of each light beam from the rotary polygon mirror to the surface to be scanned is the same, the optical path from the rotary polygon mirror to the final turning mirror is asymmetric with respect to the rotation axis of the rotary polygon mirror. By turning the optical path back,
The optical scanning device can move relative to the photoconductor unit. Therefore, the degree of freedom in arranging the optical scanning device and the photoconductor unit in the image forming apparatus is improved, and the miniaturization of the apparatus can be promoted.

In the optical scanning device according to any one of the first to fifth aspects, the upper part of the housing is opened and each light beam is emitted from this open side. May be.

Further, in the optical scanning device according to the sixth aspect, the rotating polygon mirror is arranged on the bottom surface of the housing as in the seventh aspect, so that each light beam is folded back in a direction away from the bottom surface. And a plurality of folding mirrors may be provided.

The color image forming apparatus according to claim 8 is
The optical scanning device according to any one of claims 1 to 7, and the latent image is arranged in parallel above the optical scanning device, and each of the latent images is formed by each of the light beams emitted from the optical scanning device. A plurality of photoconductors to be formed; a plurality of developing means for developing each of the latent images to form each of the developed images; and And an intermediate transfer belt for successively superimposing and superimposing the superimposed image on a sheet of paper.

In the color image forming apparatus according to the present invention, the optical scanning device and the intermediate transfer belt have substantially the same length in the belt moving direction and have respective end portions. The paper may be conveyed in a substantially vertical direction on the side of the intermediate transfer belt and discharged upward.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

[First Embodiment] As shown in FIG. 1, an optical scanning device 10 according to a first embodiment is mounted on a main body frame 14 in an image forming apparatus, and a housing 16 is a screw (not shown). It is fixed at.

A plurality of light sources for emitting laser beams AY, AM, AC, and AK modulated according to image information from a semiconductor laser are provided in the housing 16, and these laser beams AY, AM, AC, and Each collimator lens which makes AK substantially parallel light, and laser beams AY and A which are located behind each collimator lens and are made substantially parallel light
Each opening for shaping M, AC, and AK into a desired spot diameter is provided. Here, illustration is omitted.

At the center of the bottom surface 16A of the housing 16, a polygon mirror 20 for deflecting and scanning the laser beams AY, AM, AC and AK is provided.
Scanning lenses 22 (22a, 22b), 2
2 ′ (22a ′, 22b ′) and a plurality of reflection mirrors 2
4, 24 ', 26 (26Y, 26M, 26C, 26
K), 28 (28Y, 28M, 28C, 28K), 30
(30Y, 30M, 30C, 30K) are arranged and 4
In this configuration, the two photoconductors 32Y, 32M, 32C, and 32K are simultaneously scanned. Scanning exposed photoconductors 32Y, 32
A latent image is formed on M, 32C, and 32K, and the latent image is developed, transferred, and fixed on a recording medium to obtain a print.

Next, from the polygon mirror 20 to the photosensitive member 32
The optical paths of the beams Y, 32M, 32C, and 32K will be described. However, since the optical system of the present embodiment is configured symmetrically about the rotation axis L of the polygon mirror 20, the description will be made using the optical path on the right side in the figure.

Both sides (both sides) by the polygon mirror 20
The laser beams AY and AM deflected to the right in FIG.
After passing through the polygon mirror 2, both of the polygon mirrors 2 are reflected by the reflection mirrors 24 arranged near the side ends in the housing 16.
It is folded back to the 0 side. The laser beams AY and AM folded by the reflection mirror 24 are reflected by the reflection mirrors 26Y and 26M, respectively.

Here, the laser beams AY and AM (not shown) incident on the polygon mirror 20 have different angles in the sub-scanning direction, whereby the beam interval gradually increases, and the reflection mirrors 26Y, At 26M, each laser beam can be selectively reflected.

By setting the optical path so that the interval between the two laser beams is minimized near the reflecting surface of the polygon mirror 20, bidirectional scanning by a single polygon mirror 20 is possible.

The light beams turned back by the reflection mirrors 26Y and 26M are turned back by the reflection mirrors 28Y and 28M and the reflection mirrors 30Y and 30M, respectively, and then the sealing glass 3 provided at the opening of the housing bottom surface 16A.
The light passes through 4Y and 34M and reaches photoconductors 32Y and 32M.

In the configuration of the optical scanning device 10 shown in FIG. 1, the photoconductors 32Y and 32Y are reflected from the reflection mirrors 26Y and 26M.
Each optical path up to M is folded in a range that does not overlap each other in the sub-scanning direction. Thereby, the two optical paths can be laid out regardless of the arrangement of the optical components, and the height of the optical scanning device can be suppressed to a minimum.

In this embodiment, the single reflecting mirror 24 is used in common for the laser beams AY and AM. However, if the distance between the two laser beams can be set sufficiently large at this position, two adjacent reflecting mirrors can be used. The light may be reflected for each laser beam using a mirror. Thereby, the reflection mirror 24
Since the subsequent optical paths can be laid out more freely, the occupation range of the optical paths in the housing 16 can be reduced, and a more compact optical scanning device can be obtained.

FIG. 2 shows a conventional tandem optical scanning device 100 in which a plurality of optical scanning devices are arranged in series (FIG. 2A).
And the optical scanning device 10 according to the present embodiment (FIG. 2B)
FIG. 4 is a diagram for comparing the size and the occupied space of FIG.

In the configuration of this embodiment, a pair of scanning lens groups (scanning lens 22
(22a, 22b), 22 '(22a', 22b ')), and each scanning lens group is commonly used by two laser beams having slightly different angles in the sub-scanning direction. It is.

As a result, the number of polygon mirrors and scanning lens groups can be reduced as compared with the tandem system.
The lateral occupation width of the optical scanning device can be reduced.

As shown in FIG. 2B and FIG.
Reflecting mirror 2 provided near both ends of housing 16
At 4 and 24 ', the optical path is turned toward the polygon mirror 20, and the optical path is turned back and forth within the housing 16 by three reflecting mirrors. Thereby, the housing 1
6 can be reduced in width (W).

Further, the reflection mirrors 26Y, 26M, 26
C, 26K to final reflection mirrors 30Y, 30M, 30
The height dimension (H) of the housing 16 can be reduced by folding the optical paths up to C and 30K in a range that does not overlap in the sub-scanning direction.

FIG. 3 shows the relationship between the folded optical path and the height of the optical scanning device (left half of the optical scanning device).

As shown in FIG. 3B, when two laser beams (AC, AK) are folded back in the sub-scanning direction, the optical path (AC) of cyan (C) becomes the optical path of black (K). Since the mirror 16 is folded around the reflection mirror 26K disposed on (AK), the height dimension (HB) of the housing 16 is increased. On the other hand, in FIG. 3A of the present embodiment, since the optical path (AC) and the optical path (AK) are folded back in an independent range where they do not overlap in the sub-scanning direction, the degree of freedom is high without considering optical path interference. An optical path layout is possible, and the height dimension (HA) of the housing 16 can be minimized (HA <H
B).

As described above, in the optical scanning device 10 according to the present embodiment, the laser beams AY, AM, AC,
A polygon mirror 20 that deflects and scans AK, and laser beams AY, AM, AC, and AK deflected by the polygon mirror 20 with an angle difference in the sub-scanning direction are imaged on the corresponding photoconductors 32Y, 32M, 32C, and 32K. Common scanning lenses 22 (22a, 22b) and 22 '(2
2a ', 22b'), common reflecting mirrors 24, 24 'for reflecting the respective laser beams passing through the common scanning lens toward the polygon mirror 20, and respective laser beams reflected by the common reflecting mirror. A plurality of reflection mirrors 26 (26Y, 26M, 26C, 26K) that are folded back to the photoconductor,
28 (28Y, 28M, 28C, 28K), 30 (30
Y, 30M, 30C, 30K), a plurality of light sources, a polygon mirror 20, a common scanning lens 22,
2 ′, a common reflecting mirror 24, 24 ′, and an optical scanning device having a housing 16 accommodating a plurality of reflecting mirrors 26, 28, 30;
On each optical path from the 4 'to the photoconductors 32Y, 32M, 32C, and 32K, three reflection mirrors (reflection mirror 2) are provided.
6, 28, 30), and these reflecting mirrors 26, 2
8, 30 out of the reflection mirrors 24, 24 'to the photoconductor 32
The reflection mirrors 28M and 28C constituting the optical paths (AM and AC) toward M and 32C are located on the optical path from the reflection mirrors 24 and 24 'to the photoconductors 32Y and 32K. The optical scanning device can be miniaturized because it does not overlap the optical path formed by the reflection mirrors 30Y and 30K in the sub-scanning direction.

[Second Embodiment] Next, a second embodiment of the present invention will be described. In this second embodiment,
The same components as those described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

The optical scanning device 40 according to the second embodiment shown in FIG. 4 is an optical system similar to that of the first embodiment. Here, the laser beams AY, AM, AC, and AK are also used as a common reflection mirror. Folded by three reflecting mirrors, the photoconductor 32
Y, 32M, 32C, and 32K.

From the polygon mirror 20 to the reflection mirror 28
(28Y, 28M, 28C, 28K) is the first
This is the same as the embodiment. Also here, the reflection mirror 2
6, 28, and 30 of the reflecting mirrors that constitute the optical path from the reflecting mirrors 24 and 24 'to the photoconductors 32M and 32C.
M and 28C are moved from the reflection mirrors 24 and 24 'to the photoconductor 32.
Reflection mirrors 26Y, 2 on the optical path to Y, 32K
6K, reflection mirrors 28Y, 28K, reflection mirror 30Y,
It is arranged so as not to overlap with the optical path constituted by 30K in the sub-scanning direction.

In this embodiment, the reflection mirror 30
(30Y, 30M, 30C, 30K), each laser beam is turned upward, and openings (sealing glass 34Y, 34M, 34C,
34K).

Thus, the bottom surface 17A of the housing 17
And the housing 17 can be maintained at a high rigidity.

FIG. 5 is a diagram showing the relationship between the housing and the photosensitive member. As shown, the laser beams AY, AM, A
Opening 19 in which C and AK are formed on the bottom surface of housing 19
A, 19M, 19C, and 19K, and
In the case of a configuration for scanning Y, 32M, 32C, and 32K, it is necessary to provide openings at regular intervals on the bottom surface of the housing. In addition, since the scanning length of the laser beam is the largest in the housing at the opening position, the opening is a long opening crossing the housing 19.

This reduces the rigidity of the housing,
Deformation due to mounting or temperature change may be likely to occur. Therefore, a problem of causing a color shift of a full-color image due to a shift of the exposure position of the laser beam easily occurs, and a color shift due to vibration or the like easily occurs.

On the other hand, in the present embodiment, no opening is provided in the bottom surface 17A of the housing 17 and the housing 1
Since the opening is provided in the top plate 18 disposed on the upper part 7 and the laser beam is emitted from the opening, the rigidity of the housing 17 can be secured.

In this embodiment, the polygon mirror 20 and the scanning lenses 22 and 2 are provided on the bottom surface 17A of the housing 17.
2 'is arranged, and each beam is folded in a direction (upward) away from the bottom surface 17A.

For this reason, the scanning width on the optical path, which gradually increases as the distance from the polygon mirror 20 increases, becomes longer toward the upper side of the housing 17. Therefore, the long reflecting mirror is disposed in a direction away from the bottom surface 17A, and
The optical components are arranged in such a manner that they become larger as the distance from 7A increases. This facilitates the configuration of the optical component mounting reference surface in the housing 17 and simplifies assembly of the device.

[Third Embodiment] Next, a third embodiment of the present invention will be described. FIG. 6 shows an optical scanning device 50 according to a third embodiment of the present invention. The configuration of the folding of the optical path is the same as that of the second embodiment.

The present embodiment is different in that the relative position of the optical scanning device with respect to the photosensitive member is shifted by δ.
Since the final reflection mirrors 30Y, 30M, 30C, and 30K cannot move with respect to the photoconductors 32Y, 32M, 32C, and 32K, first, from the polygon mirror 20 to the third reflection mirrors 28Y, 28M, 28C, and 28K by δ in parallel. Move. Then, in the optical paths AY and AM of yellow (Y) and magenta (M), the distance from the reflecting mirrors 28Y and 28M to the reflecting mirrors 30Y and 30M becomes shorter, and the optical paths AC and AK of cyan (C) and black (K). In this case, the distance from the reflection mirrors 28C and 28K to the reflection mirrors 30C and 30K increases. FIG. 6 shows the result of adjusting the positions of the reflection mirrors 24, 24 ', the reflection mirrors 26Y, 26M, 26C, 26K, and the reflection mirrors 28Y, 28M, 28C, 28K to adjust the optical path length.

As described above, the relative position of the optical scanning device 50 with respect to the photoconductors 32Y, 32M, 32C, and 32K is adjusted by making the turn of the optical path inside the housing 17 asymmetric with respect to the rotation axis L of the polygon mirror 20. can do.

FIG. 7 is a diagram for explaining the relative positional relationship between the optical scanning device and the photosensitive unit. The exposure point (the incident position of the light beam) on the photoreceptor is determined by the electrophotographic process design of charging, exposure, development, and transfer. As shown in FIG. ).

In such a case, the area formed by the four photoreceptor units (32Y, 32M, 32C, 32K) and the position of the optical scanning device 52 are shifted in the direction of the arrow X in the figure (δX in the figure). Therefore, miniaturization of the image forming apparatus is hindered.

Therefore, in this embodiment, the optical path length from the polygon mirror 20 to the photoconductors 32Y, 32M, 32C and 32K is set to be the same for each beam, and the final reflection mirror 30
The optical path folding in the housing 17 of the two optical systems disposed on both sides of the polygon mirror 20 is made asymmetric with respect to the rotation axis L of the polygon mirror 20 without changing the positions of Y, 30M, 30C and 30K. The optical scanning device 50
Relative movement of the optical scanning device can be provided, so that an optical scanning device having a large degree of freedom in device layout can be provided, and the entire image forming apparatus can be downsized.

Although only the relative positional relationship between the optical scanning device and the photosensitive unit has been described here, it is important to increase the degree of freedom in arranging the occupied area of the optical scanning device after fixing the exposure point of the light beam. The object to be considered for the shift amount is not limited to the photoconductor unit.

[Fourth Embodiment] FIG. 8 shows a fourth embodiment of the present invention. FIG. 2 shows a cross section of the color image forming apparatus 60, and the optical scanning apparatus is described in the third embodiment.

The laser beam modulated according to the image signal is deflected and scanned by the optical scanning device 50 to expose the photosensitive members 32Y, 32M, 32C and 32K arranged in parallel in the horizontal direction.

The electrostatic latent images formed on the respective photoconductors are developed by respective developing units (not shown), and are transferred onto an intermediate transfer belt 64 at a primary transfer point 62. On the intermediate transfer belt 64, a transfer image superposed in the order of Y, M, C, and K is fed at a secondary transfer point 66 to the sheet cassette 6
The image is collectively transferred onto the sheet 69 sent out from the printer 8, becomes a fixed image by the fixing device 70, and is discharged to the sheet discharge tray 72.

As shown, by arranging the photoconductors 32Y, 32M, 32C, and 32K in parallel below the intermediate transfer belt 64, the distance from the first primary transfer point 62 to the paper discharge tray 72 is reduced. And the time required for discharging the first print image can be shortened. If the photoconductor is placed above the intermediate transfer belt, half the circumference of the belt will be idle,
Productivity decreases.

Further, in order to suppress the height of the color image forming apparatus, the height of both the intermediate transfer belt and the optical scanning device is reduced, and the structure is extended in the lateral direction. The optical scanning device, as described in the first to third embodiments,
By folding back and injecting from the housing in a range where they do not overlap each other, the thickness can be reduced. Further, as shown in the third embodiment, by making the optical path turning asymmetric with respect to the rotation axis L of the polygon mirror 20, the photoconductor 32Y,
The relative position of the optical scanning device 50 with respect to 32M, 32C, and 32K can be changed.

By mounting an optical scanning device incorporating these components in a color image forming apparatus having the above layout, high speed (tandem configuration), high image quality (intermediate transfer belt), miniaturization (thin optical scanning with a high degree of freedom in arrangement) Device) is realized.

In the present embodiment, the intermediate transfer belt 6
4 and the optical scanning device 50 have substantially the same width, and are arranged with their ends aligned.

In this case, the paper is vertically conveyed from the paper feed cassette 68 and is discharged to the paper discharge tray 72 at the upper part of the apparatus, so that the same apparatus configuration as that of the conventional monochrome multifunction peripheral is adopted. Color image forming apparatus,
The intermediate transfer belt and the optical scanning device have a configuration in which both of them extend in the lateral direction of the device with the photoconductor row interposed therebetween. Therefore, the width of the intermediate transfer belt 64 and the width of the optical scanning device 50 are made substantially the same,
By arranging the end portions, the space in the full-color image forming apparatus can be effectively used, and high-density mounting without wasting space can be performed, so that the apparatus can be made more compact.

[0076]

Since the optical scanning device of the present invention has the above-described configuration, it is possible to realize a high-speed, compact, and low-cost full-color image forming apparatus. Further, the degree of freedom in the arrangement of the relative positional relationship between the photoconductor and the optical scanning device in the full-color image forming apparatus can be improved, and the miniaturization of the full-color image forming apparatus can be promoted.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an optical scanning device according to a first embodiment of the present invention.

FIG. 2 shows a conventional tandem optical scanning device (A);
FIG. 2 is an explanatory diagram for comparing the size and the occupied space of the optical scanning device (B) in FIG. 1.

FIG. 3 is a diagram for explaining the relationship between the folded optical path and the height of the optical scanning device.

FIG. 4 is a configuration diagram of an optical scanning device according to a second embodiment of the present invention.

FIG. 5 is a schematic perspective view showing a positional relationship between a housing having an opening formed on a bottom surface and a photoconductor.

FIG. 6 is a configuration diagram of an optical scanning device according to a third embodiment of the present invention.

FIG. 7 is a diagram for explaining a relative positional relationship between the optical scanning device and the photoconductor unit.

FIG. 8 is a configuration diagram of an optical scanning device and an image forming apparatus according to a fourth embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of a conventional tandem type full-color image forming apparatus.

FIG. 10 is a diagram illustrating the features of a monochrome digital multifunction peripheral.

[Explanation of symbols]

Reference Signs List 10 optical scanning device 16, 17 housing (housing) 16A, 17A bottom surface 20 polygon mirror (rotating polygon mirror) 22 (22a, 22b), 22 '(22a', 22)
b ') Scanning lens (imaging optical system) 24, 24' Reflection mirror (common reflection mirror) 26Y, 26M, 26C, 26K Reflection mirror (return mirror) 28Y, 28M, 28C, 28K Reflection mirror (return mirror) 30Y , 30M, 30C, 30K Reflecting mirror (folding mirror) 32Y, 32M, 32C, 32K Photoconductor (scanned surface) 40, 50 Optical scanning device 60 Color image forming device 64 Intermediate transfer belt AY, AM, AC, AK Laser beam (Light beam) L Rotation axis

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 15/16 B41J 3/00 D 5C072 H04N 1/04 H04N 1/04 D 1/113 104A F-term (reference) ) 2C362 AA42 BA50 BA51 BA83 BA87 BA90 CA39 CB80 DA03 DA04 DA06 DA08 2H030 AA06 AA07 AB02 AD05 BB02 BB42 BB53 2H032 BA09 BA17 BA23 2H045 AA01 BA22 BA34 CA63 DA02 DA04 2H076 AB06 AB12 AB18 EA01 BA07 A03 DA06

Claims (9)

[Claims] 1. A single rotating polygonal mirror for deflecting and scanning each light beam incident from a plurality of light sources at different angles in the sub-scanning direction, and deflecting at an angle in the sub-scanning direction by the single rotating polygonal mirror. A common imaging optical system for forming an image of each of the formed light beams on a corresponding scanning surface, and reflecting each light beam passing through the common imaging optical system toward the single rotating polygon mirror. A common reflecting mirror, and a plurality of turning mirrors for turning each light beam reflected by the common reflecting mirror to the respective scanned surface, the plurality of light sources, the single rotating multi-surface. A mirror, the common imaging optical system, the common reflection mirror, and an optical scanning device including a housing for accommodating the plurality of return mirrors; At least one of the light paths The path has two or more return mirrors on an optical path from the common reflection mirror to the surface to be scanned, and constitutes an optical path from the common reflection mirror to one surface to be scanned among the plurality of return mirrors. An optical scanning device, wherein a folding mirror does not overlap with an optical path formed by the two or more folding mirrors on an optical path from a common reflection mirror to another surface to be scanned in the sub-scanning direction. 2. The apparatus according to claim 1, wherein the common reflection mirror is arranged near a side end in the housing.
3. The optical scanning device according to claim 1. 3. The optical scanning device according to claim 1, wherein the common reflection mirror includes a plurality of adjacent reflection mirrors. 4. The common imaging optical system, the common reflection mirror, and the plurality of folding mirrors are respectively disposed on both sides of a rotation axis of the single rotating polygon mirror, and 4. The optical scanning device according to claim 1, wherein each light beam emitted from each of the light sources is deflected and scanned to both sides of the rotary polygon mirror. 5. A single rotating polygonal mirror for deflecting and scanning each light beam incident from a plurality of light sources at different angles in the sub-scanning direction, and the single rotating polygonal mirror having an angle difference in the sub-scanning direction. A common imaging optical system that forms an image of each deflected light beam on a corresponding scanning surface, and reflects each light beam that has passed through the imaging optical system toward the single rotating polygon mirror. A common reflecting mirror, and a plurality of turning mirrors that turn each of the light beams reflected by the common reflecting mirror to the respective scanned surfaces, wherein the common imaging optical system and the common A reflection mirror and the plurality of folding mirrors are respectively disposed on both sides of a rotation axis of the single rotating polygon mirror, and each light beam emitted from each of the plurality of light sources is disposed on both sides of the rotating polygon mirror. Is deflected and scanned, and a housing for accommodating them is provided. In the optical scanning device, the optical path length of each light beam from the rotary polygon mirror to the surface to be scanned is the same, and the optical path from the rotary polygon mirror to the final turning mirror is asymmetric with respect to the rotation axis of the rotary polygon mirror. An optical scanning device, comprising: 6. The optical scanning device according to claim 1, wherein an upper portion of the housing is open, and the light beams are emitted from the open side. 7. The rotating polygon mirror is arranged on a bottom surface of the housing, and the common reflection mirror and the plurality of folding mirrors are arranged so that each of the light beams is folded in a direction away from the bottom surface. The optical scanning device according to claim 6, wherein: 8. An optical scanning device according to claim 1, wherein the optical scanning device is arranged in parallel above the optical scanning device, and each of the light beams emitted from the optical scanning device. A plurality of photoconductors on which each latent image is formed, a plurality of developing means for developing each of the latent images to form each developed image, and disposed over the plurality of photoconductors, A color image forming apparatus, comprising: an intermediate transfer belt for superimposing and transferring the superimposed images onto a sheet by sequentially superimposing the respective developed images. 9. The color image forming apparatus according to claim 8, wherein the optical scanning device and the intermediate transfer belt have substantially the same length in the belt moving direction and are arranged with their respective ends aligned, A color image forming apparatus, wherein the sheet is conveyed in a substantially vertical direction on a side portion of the intermediate transfer belt and discharged upward.