JP2003266785A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the cost of parts or the cost of adjustment in the manufacturing process and to realize the reduction of the space by a constitution wherein a single laser light source and a single scanning polygon mirror in an image exposing unit are shared by all colors in a color image forming apparatus. <P>SOLUTION: There is disclosed an image forming apparatus wherein the laser beam light from the single light source is scanned by being reflected by the single polygon mirror by rotating the polygon mirror and a lens for performing fθ correction of the laser beam light, deflecting the light in a direction perpendicular to the main scanning direction, and imaging on a latent image carrier body is used. The polygon mirror includes the even number (four or more) of reflection faces having two different angles with respect to the direction of the rotational axis which are alternately disposed. The laser beam light is deflected by the polygon mirror in the direction of the rotational axis and the lens divides the laser beam light into two beams in the scanning direction and deflects each of beams to advance them two directions, respectively so that four laser beam lights in the four directions are produced and images of four colors can be exposed. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming technique, and in particular, it is applied to a technique for printing a plurality of colors on a paper medium or the like through a photoconductor such as a color image forming apparatus or a laser beam copying machine. And about effective technology.

[0002]

2. Description of the Related Art As a conventional reference technology, a tandem type color laser beam printer or a laser beam copying machine having a plurality of scanning optical system units as shown in FIG. 6 is known. In this color image forming apparatus, as shown in FIG. 6, a plurality of semiconductor lasers 101 (a) -101 are used.
A plurality of polygon mirrors 102 are provided on the outgoing optical path of (d).
(A) to 102 (d) are arranged, and a plurality of lenses 103 (a) to 103 (d) and the reflection mirror 10 are arranged on the reflection optical path.
A plurality of sets of scanning optical system units each having a configuration in which 4 (a) to 104 (d) are respectively arranged are provided, and a plurality of photoconductor drums 105 (a) are provided on the respective emission optical paths of the plurality of sets of scanning optical system units. ~ 105 (d) are arranged. The information of each color of yellow, magenta, cyan, and black is stored in the plurality of photosensitive drums 105 (a) to 105 by the laser beam emitted from each scanning optical system unit.
It is written as an electrostatic latent image on (d). Then, the visible image obtained by developing the electrostatic latent image corresponding to each primary color on each of the photoconductor drums 105 (a) to 105 (d) is transferred with each color being superimposed on the paper, Further, the image on the paper is fixed by the fixing device to form a color print.

As another conventional technique, for example,
The following color laser beam printers are disclosed. That is, a polygon mirror is arranged on the emission light path of the semiconductor laser, a plurality of movable light path switching mirrors are arranged on the reflection light path so as to be swingable at predetermined intervals, and a plurality of photosensitive drums are arranged on the respective reflection light paths. To place. The information of each color is that one optical path switching mirror corresponding to the color is positioned on the optical path of the laser beam and the other is retracted so that the optical path of the laser beam is switched sequentially at high speed by the optical path switching mirror. Thus, the laser beam is applied to the photosensitive drum and written. The visible image obtained by developing each photosensitive drum is transferred by superimposing each color on the paper, and the image on the paper is
It is fixed by a fixing device to form a color print.

[0004]

However, in the above-mentioned conventional polygon mirror, since the reflection angles of the respective reflection surfaces are all the same and the laser beam emitted from the semiconductor laser is reflected in the same direction, In a color laser beam printer or a laser beam copying apparatus as shown in FIG. 6, a scanning optical system unit including a semiconductor laser, a polygon mirror, a lens, and a mirror has the same number of colors (for example, Y,
(4 sets of M, C, K) are required in duplicate, and there are technical problems such as an increase in device cost and an increase in device shape.

Further, in the above-mentioned color laser beam printer, although the light source and the polygon mirror need only be one set,
There is no difference in that the reflection angles of the reflection surfaces of the polygon mirror are all the same, and the optical path of the reflected laser beam is constant. Therefore, this constant optical path is changed to the number of colors (4
4 optical path switching mirrors with mechanical displacement are required to distribute and scan to a plurality of photosensitive drums provided for each color), and position control of 4 optical path switching mirrors with mechanical displacement is required. In order to perform with high precision and to perform optical path switching at high speed, a high-speed movable mechanism with high component accuracy is required for manufacturing the optical path switching mirror.
There is a technical problem that the cost of the device is increased as a result of complicated adjustment of the optical system at the time of manufacturing the device.

An object of the present invention is to reduce the number of parts, which can reduce the cost of parts of the color image forming apparatus, reduce the external dimensions of the apparatus, and reduce the man-hours for adjusting the optical system to reduce the manufacturing time of a single apparatus. An object of the present invention is to provide an image forming technique capable of reducing manufacturing cost due to shortening.

Still another object of the present invention is to provide an image forming technique capable of printing a highly accurate color image at low cost with simple control.

[0008]

According to the present invention, a latent image carrier and an exposure laser beam emitted from a single light source according to image information of different colors are reflected by one rotatable polygon mirror. While scanning by the rotation, the laser beam light is corrected by fθ, and is deflected in a direction perpendicular to the scanning direction by the polygon mirror, and
A single image exposure means for forming an electrostatic latent image on the latent image carrier through a lens for focusing on the latent image carrier, and a latent image formed by the image exposure means by a developer. Four developing means for forming a visible image to form an image on the latent image carrier, a transfer means for transferring a color image formed on the latent image carrier to a transfer material, and an undecided state on the transfer material. In an image forming apparatus having a fixing means for fixing a fixed developer color image on a transfer material, the polygon mirror has an outer peripheral surface of an even number of four or more, and the outer peripheral surface of the polygon mirror is a rotary shaft. The angle with respect to the direction consists of two different angles for every other surface, the laser beam light changes its traveling direction to the polygon mirror rotation axis direction for every other surface of the outer peripheral surface, and the lens is divided into two in the scanning direction. Yes, the two split lens is Moreover changed in two directions the traveling direction of the exposure laser beam is, produce an exposure laser beam to a total of four directions, in which to form an electrostatic latent image on a different latent image bearing member.

More specifically, for example, in the only polygon mirror as a rotary reflector, the reflection angle of each reflecting surface is set to two different angles for every other surface.
The structure is such that the laser beam is reflected in two different directions. The laser beams reflected by the two reflecting surfaces having different reflecting angles respectively travel in different directions, but the laser beam light on the optical path undergoes fθ correction and is scanned by the polygon mirror. The lens for deflecting in the direction perpendicular to and passing through the same lens for focusing on the latent image carrier. However, by converging the laser beam in two directions by the two lenses divided at the center of the scanning range of the laser beam due to the rotation of the polygon mirror, the polygon mirror has two directions, and the lens has two more directions. The optical path can be divided into four directions in total. Then, each of the laser beam optical paths passes through an optical system such as a mirror for irradiating each photoconductor,
A photoconductor or a photoconductor belt that forms latent images of primary colors of yellow, magenta, cyan, and black is scanned. By controlling the rotation of the polygon mirror and the emission of the laser beam, the laser beam having the information of each color of yellow, magenta, cyan, and black travels through a different fixed route, and image exposure corresponding to each color information is performed. I do.

The number of reflecting surfaces of the polygon mirror is an even number of four or more, and when four colors of yellow, magenta, cyan and black are used, the reflecting surfaces of the polygon mirror have two different angles. It only needs to be 4 sides. When the polygon mirror has four reflection surfaces, the polygon mirror can be half-turned to write color information of four colors to each photoconductor. Further, in the case of a six-sided polygon mirror, a structure having three reflecting surfaces with the same inclination angle is provided so that four-color data is written on the photosensitive member three times during one rotation of the polygon mirror. If there are eight surfaces, the structure having four reflection surfaces with the same inclination angle is provided so that the data for four colors is written to the photosensitive member four times during one rotation of the polygon mirror.

According to the present invention, since the polygon mirror and the two lenses having different reflection angles on the respective reflecting surfaces are used, both the scanning of the laser beam and the scanning of the optical path can be performed by the rotating operation of one polygon mirror. In addition, it is possible to reduce the number of parts, reduce the cost by reducing the movable parts, and realize high-precision printing by simplifying the control operation.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

The color image forming apparatus of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a side sectional view showing the basic structure of a color image forming apparatus according to an embodiment of the present invention. This color image forming apparatus is also of a tandem type having four developing units for performing printing for four colors, and each of the photosensitive drum cleaners 15 (a), 15 (b), 1
Photosensitive drum 11 to which 5 (c) and 15 (d) are attached
A developing device including (a), 11 (b), 11 (c), and 11 (d), and mirrors each having an even number of mirrors of 4 or more so that every other one of them has the same angle. A laser unit 1 having a polygon mirror (not shown) whose surface angles are inclined in two types (ab degrees and cd degrees) and a single laser diode for irradiating an image laser beam of four colors, and a laser emitted from the laser unit 1. The beams are directed to the photosensitive drums 11 (a), 11 (b), 11 (c), 11 respectively.
(D) First for folding back to form an electrostatic image
Folding mirrors 5 (a), 5 (b), 5 (c), 5
(D) and the second folding mirrors 6 (a), 6 (b),
6 (c), 6 (d) and the third folding mirror 7
(A), 7 (b), 7 (c), 7 (d) and the photosensitive drums 11 (a), 11 (b), 1 upon being irradiated with the laser beam.
Developing units 10 (a), 10 (b), 10 (c), 10 for forming a toner image on 1 (c), 11 (d)
And (d).

Further, in this color image forming apparatus, the driving roller 18 for feeding and conveying the paper 23 from the paper feeding unit, the first driven roller 19, and the second driven roller 2 are used.
0, a third driven roller 21, a paper feed roller 24, and a transport roller 25, and a photosensitive drum 11 (a), 11 (b), 11 for transporting the paper 23.
(C), the transfer belt 16 provided with a transfer belt cleaner 22 for sequentially superposing the monochromatic toner images formed on 11 (d) on the paper 23 to form one toner image, and the transfer belt 16. A fixing unit 26 that fixes the toner image on the sheet 23 by heat and pressure, a discharge unit that discharges the fixed sheet 23 to the outside of the apparatus, a discharge tray that stacks the discharged sheet 23, and the like. To be done.

Of these, the photosensitive drums 11 (a), 11
Main chargers 14 (a), 14 (b), 14 (c), 14 are provided near (b), 11 (c), 11 (d).
(D) is provided, and transfer devices 17 (a), 17 (b), 17 (c), 17 (d) are provided with the transfer belt 16 interposed therebetween.
Is provided, and the photosensitive drums 11 (a), 11
(B), 11 (c) and 11 (d) are the developing roller 12
(A), 12 (b), 12 (c), 12 (d) are arranged in proximity to the developing rollers 12 (a), 12 (b), 12
(C), 12 (d) and toner stirring member 13 (a), 1
3 (b), 13 (c), and 13 (d) are rotated by the drive from the photosensitive drum.

That is, in this color image forming apparatus, the number of mirror surfaces in one laser diode 1 is an even number of 4 or more, and two different mirror surface angles are used so that every other one of them has the same angle. The laser beam is radiated to one surface of the polygon mirror in order by one laser unit for each data of two colors, and the laser beam irradiation of the two surfaces of the polygon mirror exposes four lines of image for each line. It is configured to be possible.

FIG. 2 is a perspective view showing a simplified structure of a main part of the color image forming apparatus. Here, the number of mirror surfaces is an even number of 4 or more, and two kinds of mirror surface angles (ab) are set so that every other middle surface has the same angle.
In the polygon mirror 2 tilted at an angle of .degree., Cd degree), the image laser beams for four colors emitted from the laser diode (LD) 3 are controlled so as to be respectively applied to the surfaces of the polygon mirror 2 inclined by a predetermined degree. After being deflected by the surface of the lens and passing through the lenses 4 (ac) and 4 (bd), the first
Folding mirrors 5 (a), 5 (b), 5 (c), 5
(D) and the second folding mirrors 6 (a), 6 (b), 6
(C), 6 (d) and the third folding mirror 7 (a), 7
(B), 7 (c), and 7 (d) change the optical paths respectively, and then the photosensitive drums 11 (a), 11 for dedicated colors are used.
It is shown that scanning is performed along the arrow direction on (b), 11 (c), and 11 (d).

In other words, the image laser beam of the specific color emitted from the laser diode 3 is reflected by the polygon mirror 2.
Of the photosensitive drums 11 (a), 11 (b), 11 (c), for four types of dedicated colors, which are irradiated and deflected on a surface inclined by a predetermined degree and then further deflected by two lenses.
The first folding mirrors 5 (a) and 5 (a), 5 in the three types of folding mirrors that change the optical path for scanning on 1 (d)
In (b), 5 (c) and 5 (d), the deflected beam is reflected and the second folding mirrors 6 (a), 6 (b), 6
In (c) and 6 (d), the reflected beam is reflected again, and the third folding mirrors 7 (a), 7 (b), 7 (c), 7
In (d), the re-reflected beam is scanned on the dedicated color photosensitive drums 11 (a), 11 (b), 11 (c), and 11 (d).

For example, when irradiating an image laser beam of color (a), the reflecting surfaces of the polygon mirror 2 are inclined by ab degrees at every other center, so that the laser diode 3 is arranged as shown in FIG. 3 (a). The image data of the color (a) is controlled so as to be irradiated with the laser beam in the first half of scanning when the polygon mirror 2 is irradiated with the ab-degree inclined surface. The laser beam thus controlled and irradiated is deflected for the first time by the ab-degree inclined surface of the polygon mirror 2 and then further deflected by the lens 4 (ac).

Thereafter, the first folding mirror 5 (a),
The optical path is changed by the second folding mirror 6 (a) and the third folding mirror 7 (a), and the photosensitive drum 11 (a) is scanned in the arrow direction to sequentially form an electrostatic image. To the formed electrostatic image, the toner (a) is attached by the developing roller 12 (a) to form a toner image (a).

The (a) color toner image on the photosensitive drum 11 (a) is first fed from the paper feed unit by the paper feed roller 24, and the transport roller 25 controls the position of the paper 23 and the position of the toner image. Then, it is transferred to the paper 23 conveyed by the transfer belt 16 rotating in the direction of the arrow by the transfer device 17 (a) provided below the transfer belt 16.

Next, as shown in FIG. 3B, in the latter half scanning when the laser beam irradiates the inclined surface of the polygon mirror ab, the laser diode 3 irradiates the image data of the color (b). . Then, the irradiated laser beam is reflected by the a of the polygon mirror 2 rotating in the direction shown in the figure.
The first deflection is performed on the b-degree inclined surface, and then the lens 4 (b
Further deflection by d).

Thereafter, the first folding mirror 5 (b),
The optical path is changed by the second folding mirror 6 (b) and the third folding mirror 7 (b), and the photosensitive drum 11 (b) is scanned in the arrow direction to sequentially form an electrostatic image.

As in the case described above, since the reflecting surface of the polygon mirror 2 is inclined by ab degrees for every other medium, the laser diode 3 irradiates the image data of color (b) on every other medium for the reflecting surface. Irradiate the photosensitive drum 11 in half the time.
(B) An electrostatic image is sequentially formed on top. To the formed electrostatic image, the developing roller 12 (b) attaches the (b) color toner to form the (b) color toner image.

The writing timing of the laser diode 3 is controlled so that the (b) color toner image on the photosensitive drum 11 (b) is superimposed on the (a) color toner image on the transfer belt 16 on the transfer belt 16. Therefore, the toner image is superposed on the (a) color toner screen on the previously transferred paper 23.

Further, as shown in FIG. 3C, the laser diode 3 irradiates the image data of the color (c) on the cd-degree inclined surface adjacent to the ab-degree inclined surface in the first half of one surface irradiation time. Then, the first deflection is performed there, then the second deflection is performed through the lens 4 (ac), and then the (c) color toner image is formed on the photosensitive drum 11 (c) via the folding mirror. Then, the (c) color toner image is superimposed on the (a) color image and the (b) color toner image on the paper 23 conveyed to the transfer belt 16.

Subsequently, as shown in FIG.
When the image data of the color (d) is irradiated from the laser diode 3 to the surface of the slope of cd next to the surface of the slope of b in the latter half of the irradiation time of one surface, the photosensitive drum 11 (d) is colored in the color (d). A toner image is formed, and the (d) color toner image is superimposed on the (a) color toner image, the (b) color toner image, and the (c) color toner image.

FIG. 4 is a timing chart showing processing signals at the time of writing such four-color image data. That is, when the image data of four colors is written by the laser diode 3, the data of the specific color is added to the (a) color + the data of one specific inclined surface of the polygon mirror 2 in accordance with the timing of the BD signal obtained by the reference clock. (B)
Color data → (c) color + (d) color data → (a) color +
(B) The color data is sequentially controlled to irradiate the selected color on the inclined surface.

The paper 23 on which the four colors are superposed is fixed by heat and pressure applied by the fixing unit 26. The fixed paper 23 is discharged to the outside of the apparatus and stacked on the paper discharge tray.

By the way, the laser diode 3 has to irradiate the predetermined inclined surface of the polygon mirror 2 which rotates at a high speed with image data of two specific colors, but the photosensitive drums 11 (d) and 11 will be described below. (C), 11
Timings for writing electrostatic images to (b) and 11 (a) will be described with reference to the configuration of FIG.

Here, a beam detector 9 and a beam detect mirror 8 are installed on the writing side of the photosensitive drum 11 (d) in the laser beam scanning direction. With this configuration, when the (d) color image laser beam is incident on the beam detector 9, the beam detector 9 outputs a beam detection signal, so that the laser diode 3 is based on the output beam detection signal. Next ab of polygon mirror 2
The screen data of color (a) can be accurately irradiated onto the inclined surface, and the laser beam can be irradiated onto a predetermined position on the photosensitive drum 11 (a).

Therefore, by adopting such a configuration, the laser beams of the respective colors from the laser diode 3 are sequentially and accurately applied to the inclined surface of the polygon mirror 2, and the photosensitive drums 11 (a), 11 (b), 11 are obtained. (C), 11
It becomes possible to irradiate a predetermined position on (d) with a laser beam.

[0034]

As described above, according to the color image forming apparatus of the present invention, the number of mirror surfaces is an even number of 4 or more, and every other mirror surface has the same angle. Since a single laser unit having one laser diode that sequentially irradiates two faces of data for two colors on one surface of a polygon mirror inclined at two different angles is used in the conventional device, There is a laser unit for each color and the laser beam is scanned on the photosensitive drum by the laser unit for each color, but it is possible to scan the laser beam on the photosensitive drum by one laser unit. The alignment with respect to can be simplified, and the device can be downsized and the reliability can be improved.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a basic configuration of a color image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a simplified configuration of a main part of the color image forming apparatus shown in FIG.

FIG. 3 is a perspective view showing a detailed state of a laser unit included in the main part shown in FIG. 2, in which FIG. 3A shows image data of color (a) tilted by an ab degree of a polygon mirror by a laser diode. FIG. 7B shows a case of irradiating a surface with a laser diode, and FIG. 7C shows a case of irradiating the image data of the color of FIG. )
The case where the color image data of the polygon mirror is applied to the inclined plane of cd degree, the figure (d) shows the case where the image data of the color (d) is applied to the inclined surface of the polygon mirror of cd degree. is there.

FIG. 4 is a timing chart showing processing signals at the time of writing image data of four colors by the color image forming apparatus shown in FIG.

FIG. 5 is a side sectional view showing a basic configuration of a conventional color image forming apparatus.

FIG. 6 is a perspective view showing a simplified configuration of a main part of the color image forming apparatus shown in FIG.

[Explanation of symbols]

1, 51 (a), 51 (b), 51 (c), 51 (d)
Laser unit 2, polygon mirror 3, laser diode (LD) 4 (ac), 4 (bd), lens 5 (a), 5 (b), 5 (c), 5 (d), 55
(A), 55 (b), 55 (c), 55 (d) First folding mirror 6 (a), 6 (b), 6 (c), 6 (d), 56
(A), 56 (b), 56 (c), 56 (d) Second folding mirror 7 (a), 7 (b), 7 (c), 7 (d) Third folding mirror 8 Beam detect Mirror 9 Beam detectors 10 (a), 10 (b), 10 (c), 10 (d), 6
0 (a), 60 (b), 60 (c), 60 (d) Developing unit 11 (a), 11 (b), 11 (c), 11 (d), 6
1 (a), 61 (b), 61 (c), 61 (d) Photosensitive drums 12 (a), 12 (b), 12 (c), 12 (d), 6
2 (a), 62 (b), 62 (c), 62 (d) Developing rollers 13 (a), 13 (b), 13 (c), 13 (d), 6
3 (a), 63 (b), 63 (c), 63 (d) Toner stirring members 14 (a), 14 (b), 14 (c), 14 (d), 6
4 (a), 64 (b), 64 (c), 64 (d) Main charger 15 (a), 15 (b), 15 (c), 15 (d), 6
5 (a), 65 (b), 65 (c), 65 (d) Photosensitive drum cleaner 16, 66 Transfer belts 17 (a), 17 (b), 17 (c), 17 (d), 6
7 (a), 67 (b), 67 (c), 67 (d) Transfer device 18, 68 Drive roller 19, 69 First driven roller 20, 70 Second driven roller 21, 71 Third driven roller 22, 72 Transfer belt cleaner 23, 73 Paper 24, 74 Paper feeding roller 25, 75 Conveying roller 26, 76 Fixing unit

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G03G 15/04 111 B41J 3/00 D H04N 1/113 H04N 1/04 104A (72) Inventor Nobuo Nakazawa Tokyo 3-30-2 Shimomaruko, Ota-ku, Canon Inc. (72) Inventor Masami Kawada 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Masafumi Fukuda Shimomaruko, Ota-ku, Tokyo 3rd, 30th, 2nd, Canon Inc. F-term (reference) 2C362 AA10 BA05 BA50 BA53 BA85 DA09 2H045 AA04 CA63 CA88 CA98 2H076 AB05 AB06 AB08 AB12 AB18 AB22 EA01 2H300 EA01 EB04 EB07 EB12 EB27 EF02 EF06 E16 EF09 EF06 EF06 EF09 EF06 EF06 EF09 EF06 EF06 EF06 EF09 EF06 EJ09 EK03 EL04 EL07 GG35 QQ10 5C072 AA03 BA02 BA04 BA19 BA20 HA02 HA09 HA13 JA07

Claims (7)

[Claims] 1. A latent image carrier and an exposure laser beam emitted from a single light source according to image information of different colors are reflected by one rotatable polygon mirror and scanned by the rotation thereof. The fθ correction of the laser beam light is performed, the laser beam light is deflected in a direction perpendicular to the scanning direction by the polygon mirror, and the latent image carrier is passed through a lens for focusing on the latent image carrier. A single image exposure means for forming an electrostatic latent image on the body, and four image forming means for forming an image on the latent image carrier by visualizing the latent image formed by the image exposure means with a developer. The developing device has a developing device, a transfer device for transferring a color image formed on the latent image carrier to a transfer material, and a fixing device for fixing an unfixed developer color image on the transfer material on the transfer material. In the image forming apparatus, the polygon mirror The number of rotating outer peripheral surfaces of the polygon mirror is an even number of four or more, and the polygon mirror outer peripheral surface has two different angles with respect to the rotation axis direction every other surface, and the laser beam light is one of the outer peripheral surfaces. The traveling direction is changed in the rotation axis direction of the polygon mirror every other surface, and the lens is divided into two in the scanning direction, and each of the two-divided lenses further changes the traveling direction of the exposure laser beam light into two directions. A color image forming apparatus which forms an image by generating a laser beam light for exposure in a direction. 2. The latent image carrier is four photosensitive drums, and a developer image on the photosensitive drums is transferred to a transfer material once for each color, that is, four times in total. 1
The color image forming apparatus described in 1. 3. The latent image carrier is four photosensitive drums, and the developer image on the photosensitive drums is first transferred to an intermediate transfer member.
The color image forming apparatus according to claim 1, wherein the color components are superposed and then collectively transferred onto a transfer material. 4. The latent image carrier is a photoconductor belt,
2. The color image forming apparatus according to claim 1, wherein the developer images are collectively transferred onto the transfer material after the four-color image formation on the photosensitive belt is completed. 5. The fθ correction of the laser beam light,
Further, the lens for deflecting in a direction perpendicular to the scanning direction by the polygon mirror and for focusing on the latent image carrier is a lens group composed of a plurality of lenses. The color image forming apparatus according to claim 1. 6. The exposure laser beam light emitted from a single light source according to image information of different colors is reflected by one rotatable polygon mirror and scanned by the rotation, and fθ of the laser beam light is reflected. A single image exposure apparatus that performs correction, deflects in a direction perpendicular to the scanning direction of the polygon mirror, and performs image exposure through a lens for focusing on the image exposure target. In the above, the number of outer peripheral surfaces of rotation of the polygon mirror is an even number of four or more, and the outer peripheral surface of the polygon mirror has two angles different from each other with respect to the rotation axis direction, and the laser beam light is For every other outer peripheral surface, the traveling direction is changed in the direction of the rotation axis of the polygon mirror, and the lens is divided into two in the scanning direction, and each of the two divided lenses advances the exposure laser beam light. A color image exposure apparatus characterized in that the direction is further changed to two directions to produce exposure laser beam light in a total of four directions. 7. A lens for correcting f.theta. Of the laser beam, deflecting the laser beam in a direction perpendicular to the scanning direction of the polygon mirror, and focusing on the latent image carrier. 7. The color image exposure apparatus according to claim 6, wherein is a lens group including a plurality of lenses.