JPH11249042A - Optical scanning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate variance in the quantity of scanning light of the optical scanning device and variance in scanning position and to obtain the optical scanning device which is small in the number of components and small-sized and obtain more than one scanning light. SOLUTION: The optical scanning device is characterized by that a reflecting mirror has a single surface a scanning surface and Fθlenses 5a and 5b are arranged in pairs at right angles to light beams and make scans with the lights, and consequently the scanning light beams are obtained by a single light source and the single reflecting mirror. Further, the beam spot diameters by scanning positions can be made constant by sectioning lights made incident on the reflecting mirror circular.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device used for a laser beam printer, a copying machine, etc., and performs scanning by a reflecting mirror having a single light source and a single reflecting surface. Related to optical scanning devices.

[0002]

2. Description of the Related Art FIG. 2 shows a schematic view of a conventional laser beam printer. Light is generated from a light source 1, and the light is collimated by a collimator lens 2. Thereafter, the light passes through a cylinder lens 3 inserted for correcting surface tilt, and is deflected and scanned by a rotating polygon mirror 4. After that, the aperture is narrowed down on the photoconductor 6 by the Fθ lens 5. The above is the outline of the conventional optical scanning device using the rotating polygon mirror.

[0003]

Since the rotary polygon mirror shown in the conventional example is composed of a large number of reflecting mirrors, the variation in the light reflectivity becomes the variation in the light amount of the scanned light as it is. . When this occurs, the print density becomes uneven.

[0004] In addition, when the accuracy of a large number of reflecting mirrors varies, a positional shift of a scanning light beam occurs. As a result, a pitch unevenness phenomenon in printing has occurred.

In addition, when a plurality of scanning light beams are required as in a color printer, a plurality of light scanning devices are required in the conventional method, and the number of parts of the device is increased and the size of the entire device is increased. As a result, the production price increases.

[0006]

According to the present invention, a single light beam generating means capable of modulating light intensity and a light beam emitted from the generating means are deflected and scanned. In an optical scanning device comprising a reflecting mirror and an Fθ lens, the reflecting mirror is arranged so as to be a single surface and the scanning surface is arranged in a direction perpendicular to the light beam from the optical beam generating means, and a plurality of sets of Fθ lenses are arranged By allowing the Fθ lens to scan light, a plurality of scanning light beams can be obtained with a single light source and a single reflecting mirror surface.

Further, the beam spot diameter at each scanning position is made constant by making the cross section of the light entering the reflecting surface of the reflecting mirror circular.

[0008]

FIG. 1 shows an embodiment of the present invention. FIG. 1 shows a case where two scanning light beams are obtained by a single light source and a reflecting mirror having a single reflecting surface. However, the present invention can be similarly realized by using two or more configurations. In FIG. 1, light is emitted from a light source 1 and the light is collimated by a collimator lens 2. The light is incident on a reflecting mirror 7 inclined at 45 degrees to the optical axis. The reflecting mirror 7 is rotated by a motor 9, and the scanning light is scanned in a direction perpendicular to the optical axis. FIG. 1 shows a case where light in two directions is used. The light scanned by the reflecting mirror 7 is transmitted to the Fθ lens 5
The images are formed on the photoconductors 6a and 6b by a and 5b, respectively. Note that mirrors 8a and 8b may be arranged between the photoconductors 6a and 6b and the Fθ lenses 5a and 5b to bend light rays. On the photoconductors 6a, 6b, first, the chargers 10a,
It is charged by 10b and the potential of the printing section is lowered by the scanning light. Thereafter, the toner image is developed by the developing devices 11a and 11b, and the toner image is transferred onto the sheet 14 by the transfer devices 12a and 12b. Thereafter, the toner remaining on the photoreceptor that has not been transferred is cleaned by the cleaning devices 13a and 13b.
On the other hand, the toner image transferred onto the paper is
The printed material is fixed by 5b. Here, if the colors of the toners of the developing machines 11a and 11b are changed, a two-color printer is obtained.

FIG. 3 shows an example of a color printer as another embodiment. According to the present invention, four scanning light beams can be obtained by a single light source and a reflecting mirror having a single reflecting surface. In this case, printing can be performed by printing four colors (cyan, magenta, yellow, and black) on one side. In FIG. 3, light is generated from a light source 1, and the light is collimated by a collimator lens 2. The light is incident on a reflecting mirror 7 inclined at 45 degrees to the optical axis. The reflecting mirror 7 is
The scanning light is rotated by the data 9 and the scanning light is scanned in a direction perpendicular to the optical axis. FIG. 3 shows a case where light in four directions is used. The light scanned by the reflecting mirror 7 is Fθ
The photosensitive members 6a, 6 are provided by the lenses 5a, 5b, 5c, 5d.
b, 6c, and 6d. The photoconductor 6
a, 6b, 6c, 6d and Fθ lenses 5a, 5b, 5c,
During 5d, the mirrors 8a, 8b, 8
c and 8d may be arranged. Photoconductors 6a, 6b, 6c,
6d, first, the chargers 10a, 10b, 10c, 10c
It is charged by d and the potential of the printing unit is lowered by the scanning light. After that, the developing machines 11a, 11b, 11c,
11d, the transfer devices 12a, 12b, 12c, 1
The toner image is transferred onto the paper 14 in 2d. after this,
The toner remaining on the photoreceptor that has not been transferred is a cleaning device 13a,
The cleaning is performed by 13b, 13c, and 13d. On the other hand, the toner image transferred on the paper is fixed by the fixing units 15a and 15b to form a printed matter. In this method, the paper is folded back during the process so that printing can be performed on one side. Here, if the toner colors of the developing machines 11a, 11b, 11c and 11d are cyan, magenta, yellow and black, respectively, a color printer is obtained.

FIG. 4 shows an example of a two-sided two-color printer as another embodiment. According to the present invention, it is also possible to obtain four scanning light beams with a single light source and a single reflecting mirror. In this case, two-color printing can be performed on both sides by twisting the printing paper in the middle. In FIG. 4, light is generated from a light source 1, and the light is collimated by a collimator lens 2. The light is incident on a reflecting mirror 7 inclined at 45 degrees to the optical axis. The reflecting mirror 7 is rotated by a motor 9, and the scanning light is scanned in a direction perpendicular to the optical axis. FIG. 3 shows a case where light in four directions is used. Reflector 7
Are scanned by the Fθ lenses 5a, 5b, 5
Images are formed on the photoconductors 6a, 6b, 6c, and 6d by c and 5d, respectively. The photoconductors 6a, 6b, 6c, 6d
Mirrors 8a, 8b, 8c, and 8d may be arranged between the Fθ lenses 5a, 5b, 5c, and 5d to bend light rays. On the photoreceptors 6a, 6b, 6c, 6d, first, they are charged by the chargers 10a, 10b, 10c, 10d,
The scanning light lowers the potential of the printing unit. Thereafter, the toner image is developed by the developing devices 11a, 11b, 11c and 11d, and the toner image is transferred onto the paper 14 by the transfer devices 12a, 12b, 12c and 12d. Thereafter, the toner remaining on the photoreceptor that has not been transferred is cleaned by the cleaning devices 13a, 13b, 13c, 13
The cleaning is performed by d. On the other hand, the toner image transferred on the paper is fixed by the fixing units 15a and 15b to form a printed matter. In this method, the sheet is folded back during the process so that printing can be performed on both sides. Where 11
By changing the colors of the toners of the developing machines a, 11b and 11c, 11d, a two-sided two-color printer can be obtained.

Finally, the structure of the single reflecting mirror 7 of the present invention is shown in FIG. Light rays 20 and 21 are inserted from above, and light is scanned like light rays 22 and 23 while changing the angle by 90 degrees. Therefore, the reflecting mirror 7 has an incident light beam inclined at 45 degrees. The reflecting mirror 7 is rotated by rotating the rotating body 19 by the motor 9.

If the beam cross-section is not circular, the beam spot shape will differ depending on the position to be rotated and scanned. Therefore, the beam cross-section is preferably circular. By doing so, the beam spot diameter on the photosensitive member does not change depending on the scanning position.

[0013]

According to the present invention, since scanning is performed using a reflecting mirror having a single reflecting surface, variations in the amount of scanning due to variations in reflectance,
Scan line pitch unevenness due to variations in the shape of the reflecting mirror can be eliminated.

Further, since a plurality of scanning lights can be obtained with a single light source and a single reflecting mirror, the scanning light is more inexpensive and more compact than in the past. It is optimal as an optical scanning device for a printer.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment of the present invention.

FIG. 2 is a schematic view showing a conventional example of the present invention.

FIG. 3 is a schematic diagram showing a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing a third embodiment of the present invention.

FIG. 5 is an explanatory diagram of a reflecting mirror.

[Explanation of symbols]

1 is a light source such as a laser, 2 is a collimator lens, 3 is a cylinder lens, 4 is a rotary polygon mirror, 5, 5a, 5b, 5
c and 5d are Fθ lenses, 6, 6a, 6b, 6c and 6d are photosensitive members, 7 is a single-sided mirror, 8, 8a, 8b, 8c and 8d
Is a folded mirror, 9 is a motor, 10, 10a, 10
b, 10c, 10d are chargers, 11, 11a, 11b,
11c, 11d are developing machines, 12, 12a, 12b, 12
c, 12d are transfer devices, 13, 13a, 13b, 13c,
13d is a cleaning device, 14 is a sheet, 15a and 15b are fixing devices, 19 is a rotating body, and 20, 21, 22, and 23 are light beams.

Claims (2)

[Claims] 1. An optical scanning device comprising: a single light beam generating means capable of modulating light intensity; a reflecting mirror for deflecting and scanning a light beam emitted from the light beam generating means; and an Fθ lens. The reflecting mirror consists of a single surface, and the light beam
A plurality of scanning planes are provided at right angles to the light beam from the beam generating means, and a plurality of sets of Fθ lenses are arranged for each scanning plane.
An optical scanning device, wherein light is scanned on a lens. 2. The optical scanning device according to claim 1, wherein the cross section of the light entering the reflection surface is circular.