JPH06160743A - Laser beam scanner - Google Patents

Abstract

PURPOSE:To provide the laser beam scanner which can form a full color image of a high picture quality in a short time, is low in its cost, and compact, by a system using each laser beam of a necessary and arbitrary number. CONSTITUTION:In the laser beam scanner having a first image forming optical system 1 in this side of a polygon mirror 13 containing a cylindrical lens 12 for allowing a laser beam L to form an image on the polygon mirror 13, and a second image forming optical system 2 containing a cylindrical lens 15 for allowing the laser beam to form an image in an image forming position of the rear side of the polygon mirror 13, this scanner is constituted so that a first image forming optical system 1 consists of plural image forming optical systems in which the polarizing direction, or wavelength, or a combination of the polarizing direction and the wavelength of light of laser beam light sources 111-114 are different from each other, and also, which have the cylindrical lens 12 which can guide the laser beam L to the polygon mirror 13, respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser beam scanning device for scanning a laser beam to form an image, and in particular, an image is formed by sorting the laser beam according to the polarization direction and wavelength of the laser beam. The scanning device.

[0002]

2. Description of the Related Art Image formation by a conventional laser beam is
Especially in image formation in a full-color image forming apparatus,
The latent image formation and development operations by one system of laser beam scanning by one color signal have been obtained by repeating the photoconductor by the number of color signals.

FIG. 3 is a diagram showing the above conventional example.

In FIG. 3, a polygon mirror 13, f which rotates a laser diode (not shown) as a light emitting source is used.
The laser beam L modulated by the color signal for yellow (Y) development through the θ lens 14 and the cylindrical lens 15 has its optical path bent by the mirrors M1, M2 and M3, is scanned, and is charged by the charger 52. Photoconductor drum
A latent image is formed by the rotation of 51 in the direction of the arrow (sub-scanning). Then, the latent image is developed by the yellow (Y) toner developing sleeve 531 of the developing device 53 to form an image of yellow (Y) toner.

The tip of the yellow (Y) toner image reaches the charger 52 again by the rotation of the photosensitive drum 51 and is charged, and by the laser beam L modulated by the color signal for developing the next magenta (M), A latent image is formed so as to overlap with the arrival of the yellow (Y) toner image, and the latent image is developed by a developing sleeve 532 of magenta (M) toner.

By repeating this procedure, latent images of cyan (C) and black (K) are formed and developed. Therefore, when the photosensitive drum 51 rotates four times, yellow (Y), magenta (M) and cyan ( A full-color image with four color toners of C) and black (K) is formed on the photosensitive drum 51. Then, the full-color image formed on the photosensitive drum 51 is transferred and fixed on the recording paper by means not shown to be completed.

As described above, full-color image formation according to the present method involves the operation of latent image formation and development by one-system laser beam scanning by one color signal by rotating the photosensitive member by the number of color signals. It was obtained by repeating.

As another method, a latent image is formed and developed by scanning a laser beam of a first system with one color signal on a photosensitive member moving at a constant speed, and then the next color signal is generated. Latent image formation by scanning of the second system laser beam is performed and developed in accordance with the arrival of the developing unit by the previous color signal, and in the same manner, the third and fourth image signals by the next color signal. This method was obtained by repeating latent image formation and development by scanning with a laser beam of the above system. Therefore, according to this method, a latent image is formed by a laser beam and then developed, so that a full-color image can be formed in a short time because the latent images are successively formed next to each other.

4 and 5 are views showing the above-mentioned conventional example. First, description will be made from FIG.

In FIG. 4, in the scanning of the laser beams of the first to fourth systems described above, two-stage overlapping polygon mirrors 131 and 132 are provided, and the laser beams scanned by the polygon mirrors are respectively shown in the figure. Dedicated fθ lenses 141, 142, 143, 144, cylindrical lenses 151, 152, 153, 154, mirrors M11, M12, M13, M
A laser beam LY of the first system, which has a laser diode (not shown) that has 14 and is modulated by each color signal of yellow (Y), magenta (M), cyan (C), and black (K). , The laser beam LM of the second system, the laser beam LC of the third system, and the laser beam LK of the fourth system are scanned by the polygon mirrors 131 and 132 and moved in the arrow directions. , 524 on the photoconductor belt 511 charged by the latent images PY, PM, P
C and PK are formed.

More specifically, the polygon mirror 132 on the lower side of the rotating polygon mirrors 131, 132 in two layers is first modulated by a color signal for yellow (Y) development. The laser beam LY passes through the fθ lens 141 and the cylindrical lens 151, the optical path is bent by the mirror M11 and scanned, and the latent image PY is formed by the movement (sub-scanning) of the photoconductor belt 511 charged by the charger 521 in the arrow direction. To do. Then, subsequently, the latent image is developed by the yellow (Y) toner developing sleeve 531 to form an image of the yellow (Y) toner. The above is the latent image formation and development by the scanning of the laser beam LY of the first system.

Then, the leading edge of the image of the yellow (Y) toner reaches the next charger 522 by the movement of the photosensitive belt 511 and is charged, and the polygon mirrors 131 and 132 are rotated in two stages.
The laser beam LM of the second system, which is modulated by the color signal for developing the next magenta (M) by the upper polygon mirror 131, passes through the fθ lens 142, the cylindrical lens 152 and the optical path by the mirror M12. The latent image is bent and scanned, and a latent image is formed so as to overlap with the arrival of the image of the yellow (Y) toner, and then the latent image is developed by the developing sleeve 532 of the magenta (M) toner. The above is the latent image formation and development by the scanning of the laser beam LM of the second system.

Thereafter, the cyan (C) and black (K) latent images are formed and developed by scanning the laser beams LC and LK of the third and fourth systems by the same means as described above. ) When the development of the toner by the developing sleeve 534 is completed, a full-color image with four color toners of yellow (Y), magenta (M), cyan (C), and black (K) is formed on the photosensitive belt 511. become. Therefore, a full-color image can be formed in a short time.

Next, FIG. 5 will be described.

In FIG. 5, the laser light sources 111, 112, 113, 114 of the laser beam emitting section 110 emit laser beams having different wavelengths and polarization directions, and the four laser beams are the same as in the case described above. The laser beams of the four systems are modulated by the color signals of the four kinds of color toners and become the laser beams of the first system to the fourth system as in the case described above. A first imaging optical system 1 that is bundled as a laser beam and is scanned by a polygon mirror through a cylindrical lens.
Is formed.

More specifically, as an example, the laser light source 11
1 is a P-polarized laser beam with a wavelength of 830 nm and is yellow (Y)
The first system laser beam L1 modulated by a color signal for development is emitted.

Similarly, the laser light source 112 has a wavelength of 830n.
The laser beam L2 of the second system, which has been modulated by the magenta (M) color signal with m and S polarization, has a wavelength of 670 nm by the laser light source 113 and the third laser beam L2 with the cyan (C) color signal which is S polarization. Laser beam L3 of the system
Emits a laser beam L4 of a fourth system which is P-polarized and has a wavelength of 670 nm and is modulated by a black (K) color signal.

The first light emitted from the laser light sources 111 and 112,
The laser beams L1 and L2 of the second system are bundled as a laser beam L12 having a wavelength of 830 nm having one P-polarized light and S-polarized light by a polarization beam splitter BS2 that reflects S-polarized light and transmits P-polarized light. Similarly, the laser light source 11
The third and fourth laser beams L3 and L4 emitted from the light sources 3 and 114 reflect the same S-polarized light and transmit the P-polarized light as described above. It is bundled as a laser beam L34 having a wavelength of 670 nm.

The laser beam L12 and the laser beam L34 reflected by the mirror M reflect a laser beam having P polarization and S polarization at a wavelength of 830 nm and a laser beam having P polarization and S polarization at a wavelength of 670 nm. Is bundled as a laser beam L having wavelengths of 830 nm and 670 nm having one P-polarized light and S-polarized light by the transmitting wavelength beam splitter BS1 and is imaged on the mirror surface of the polygon mirror 13 by the cylindrical lens 12. The image optical system 1 is formed.

Then, the rotating polygon mirror 13, fθ
The laser beam L passing through the lens 14 and the cylindrical lens 15 has its optical path bent or transmitted by the wavelength beam splitter BS1, the mirror M, and the polarization beam splitters BS2 and BS3 to form a scanning image, and the photoreceptor belt charged by the charger. On the 511, a second image forming optical system 2 that forms a latent image by moving (sub-scanning) the photosensitive belt 511 in the direction of the arrow is formed.

Further details will be described with reference to FIG. FIG. 2 is a diagram for explaining the situation in which the laser beam is reflected and transmitted by the beam splitter and the mirror depending on the polarization direction of the light and the wavelength of the light. The laser beam L that has passed through the rotating polygon mirror 13, the fθ lens 14, and the cylindrical lens 15 and is bundled into one is reflected by the wavelength beam splitter BS1 and the laser beam L12 having a wavelength of 830 nm having P polarization and S polarization is also reflected. 670nm with P and S polarization
Laser beam L34 having a wavelength of
1 is transmitted.

A laser beam L12 having a wavelength of 830 nm having P-polarization and S-polarization reflected by the wavelength beam splitter BS1 is 830 n P-polarized by the polarization beam splitter BS2.
A laser beam L1 having a wavelength of m is transmitted, and a laser beam L2 having an S polarization of 830 nm is polarized beam splitter BS2.
Is reflected by.

On the other hand, the laser beam L34 having a P-polarized light and S-polarized light having a wavelength of 670 nm transmitted through the wavelength beam splitter BS1 has its optical path bent by the mirror M and the laser beam L3 having a wavelength of 670 nm having S-polarization by the polarization beam splitter BS3. Is reflected, and the P-polarized laser beam L4 having a wavelength of 670 nm is transmitted through the polarization beam splitter BS3.

As described above, the laser beam L1 is the laser beam of the first system which is modulated by the color signal of yellow (Y), and hereinafter, the laser beams L2, L3, L are similarly.
Reference numeral 4 denotes laser beams of the second, third, and fourth systems which are modulated by magenta (M), cyan (C), and black (K) color signals. Therefore, the laser beam L1 of the first system after passing through the polarization beam splitter BS2 scanned by the rotating polygon mirror 13 moves in the arrow direction of the photosensitive belt 511 charged by the charger 521 (sub-scan). To form a latent image PY. Then, subsequently, the latent image is developed by the yellow (Y) toner developing sleeve 531 to form an image of the yellow (Y) toner.

Then, the front end of the image of the yellow (Y) toner reaches the next charger 522 by the movement of the photosensitive belt 511, is charged, and is reflected by the polarization beam splitter BS2 scanned by the rotating polygon mirror 13. Second
The laser beam L2 of the above system overlaps with the arrival of the image of the yellow (Y) toner to form a latent image PM, and then the latent image is developed by the developing sleeve 532 of the magenta (M) toner.

The cyan (C) and black (K) latent images are formed and developed by the third and fourth laser beams L3 and L4 by the same means as described above.

When the development of the black (K) toner by the developing sleeve 534 is completed, a full-color image with four color toners of yellow (Y), magenta (M), cyan (C), and black (K) is formed on the photoreceptor belt 511. As described above, the full-color image can be formed in a short time as in the conventional example described with reference to FIG.

[0028]

As described above with reference to FIG. 3, in the conventional example, the operation of latent image formation and development by one system of laser beam scanning by one color signal is performed to form a full-color image. Since it is obtained by rotating the photoconductor by the number of color signals and repeating the same, it takes four times as long as an image forming time as compared with monocolor.

In the conventional example described with reference to FIGS. 4 and 5, which is an improvement on this, the latent image forming and developing operations by the laser beams of the first to fourth systems are performed next to each other one after another. The image forming time can be made much shorter than that of the conventional example described with reference to FIG.

However, in the case of the conventional example of FIG. 4, since the dedicated optical system is provided for each of the laser beams of the first system to the fourth system as described above, the structure becomes complicated and the number of parts is increased. Also increased, which in turn increased costs. Further, as shown in FIG. 4, since these optical systems are arranged on both sides of the polygon mirror, a laser beam scanning device which requires a large area in terms of space is also provided, and therefore the image forming device is also large. There was also a problem of becoming.

A further improvement of this is the conventional example described in FIG. 5, but as described above, there are four types of laser beams in which two types of wavelengths and polarization directions are combined. 4 system laser beams L1, L2, L3,
L4 is bundled as one laser beam L by the first imaging optical system 1.

In order to bundle the laser beams L1, L2, L3 and L4 of the first to fourth systems as one laser beam L, as described above, the polarization beam splitter B is used.
S2, BS3, wavelength beam splitter BS1, mirror M
Are using. And these beam splitters,
Unless the incident angles of the laser beams L1 and L4 and the further bundled laser beams L12 and L34 with respect to the mirror are completely adjusted, the single laser beam L is not completely bundled. Unless this adjustment is incomplete and the laser beam L is not completely bundled, the latent images PY, PM, PC and PK formed in the second image forming optical system are displaced from each other. The image becomes a high quality image and not a high quality image.

However, the adjustment of the laser beam L completely bundled by the above-mentioned incident angle adjustment is very delicate and difficult, and the adjustment is unstable even if it is a little. Therefore, it is very difficult to obtain a high-quality image as an image forming apparatus, and a costly beam splitter is often used in the first imaging optical system. It was a high cost device as well as adjustment costs.

The present invention has been made to solve the above problems. That is, it is an object of the present invention to provide a low-cost, compact laser beam scanning device capable of forming a high-quality full-color image in a short time by a method using an arbitrary number of individual laser beams. .

[0035]

The object is to connect a first image forming optical system on the front side of the polygon mirror including a cylindrical lens for forming an image of a laser beam on the polygon mirror to a rear side of the polygon mirror. In a laser beam scanning device having a second image forming optical system including a cylindrical lens for forming an image of the laser beam at an image position, the first image forming optical system includes polarization directions of light of the laser beam light source, Or a combination of wavelengths or polarization directions and wavelengths, and a plurality of imaging optical systems each having a cylindrical lens capable of guiding the laser beam to a polygon mirror. Further, the above-mentioned object is that the first imaging optical system is configured such that a polarization direction and a wave of light of the laser beam light source are There is one by two, is intended to be achieved by the laser beam scanning apparatus characterized by having four kinds of laser beam imaging optical system by a combination of polarization direction and wavelength.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to FIGS.

FIG. 1 is a perspective view showing an embodiment of a laser beam scanning device of the present invention.

In FIG. 1, reference numeral 110 denotes a laser beam emitting section which emits four types of laser beams.
It consists of 2, 113 and 114. The laser light source 111 emits a first system laser beam L1 modulated by a color signal for yellow (Y) development with a P-polarized laser beam having a wavelength of 830 nm, for example. Similarly, the laser light source 112 has a wavelength of 830 nm and the laser beam L2 of the second system modulated by the magenta (M) color signal with S polarization.
The laser light source 113 has a wavelength of 670 nm and is S-polarized in cyan (C).
Laser beam L of the third system modulated by the color signal of
3, a laser light source 114 has a wavelength of 670 nm, P-polarized laser beam L4 modulated by a black (K) color signal.
Is emitting.

Then, the laser beams L1, L2, L3,
L4 forms a first imaging optical system 1 in which an image is formed on the mirror surface of the polygon mirror 13 by each cylindrical lens 12 of each laser beam.

An index sensor 30 is arranged at the conjugate position of the laser light source 111, and the index sensor 30 has a wavelength filter 311 for transmitting a laser beam having a wavelength of 830 nm in front of the photosensor PS and a P-polarized light. A polarization filter 321 that transmits the laser light is overlapped as shown in the drawing. Therefore, although the laser beam L1 of the first system of the laser light source 111 can be detected, the laser light sources 112, 11
The laser beams L2, L3 and L4 of 3 and 114 cannot be detected.

Then, the rotating polygon mirror 13, fθ
Each laser beam passing through the lens 14 and the cylindrical lens 15 has its optical path bent by the wavelength beam splitter BS1, the mirror M, and the polarization beam splitters BS2 and BS3, or is transmitted and imaged for scanning to form a photosensitive belt. On the 511, a second image forming optical system 2 that forms a latent image by moving (sub-scanning) the photosensitive belt 511 in the direction of the arrow is formed.

Further details will be described with reference to FIG. FIG. 2 is a diagram for easily understanding the situation in which the laser beam is reflected and transmitted by the beam splitter and the mirror depending on the polarization direction of the light and the wavelength of the light as described above. Each laser beam passed through the rotating polygon mirror 13, the fθ lens 14, and the cylindrical lens 15 is converted into a P beam by the wavelength beam splitter BS1.
A laser beam L with a wavelength of 830 nm having polarized light and S polarized light
1 and L2 are reflected and also have P polarization and S polarization 67
The laser beams L3 and L4 having a wavelength of 0 nm pass through the wavelength beam splitter BS1.

The P-polarized and S-polarized laser beams L1 and L2 having a wavelength of 830 nm reflected by the wavelength beam splitter BS1 pass through the polarization beam splitter BS2 the P-polarized laser beam L1 having a wavelength of 830 nm, and the S-polarized laser beam L1. In 8
The laser beam L2 having a wavelength of 30 nm is reflected by the polarization beam splitter BS2.

On the other hand, the laser beams L3 and L4 having a P-polarization and S-polarization having a wavelength of 670 nm transmitted through the wavelength beam splitter BS1 have their optical paths bent by a mirror M, and a laser having a S-polarization wavelength of 670 nm having a polarization beam splitter BS3. The beam L3 is reflected, and the P-polarized laser beam L4 having a wavelength of 670 nm passes through the polarization beam splitter BS3.

As described above, the laser beam L1 is the laser beam of the first system modulated by the color signal of yellow (Y), and hereinafter, the laser beams L2, L3, and L are similarly.
Reference numeral 4 denotes laser beams of the second, third, and fourth systems which are modulated by magenta (M), cyan (C), and black (K) color signals. Therefore, the laser beam L1 of the first system after passing through the polarization beam splitter BS2 scanned by the rotating polygon mirror 13 moves in the arrow direction of the photosensitive belt 511 charged by the charger 521 (sub-scan). To form a latent image PY. Then, subsequently, the latent image is developed by a developing sleeve 531 of yellow (Y) toner, and an image of yellow (Y) toner is formed.

At the same time, the index sensor 30 detects the laser beam L1 of the first system of the laser light source 111, and after a predetermined time, the laser beams L2 of the second, third and fourth systems by the laser light sources 112, 113 and 114. , L3, L4 are sequentially emitted to form a latent image on the photoconductor 511, a latent image is sequentially formed on the developed toner image, and a toner image is formed by development to form a full-color image.

That is, the front end of the image of the yellow (Y) toner reaches the next charger 522 by the movement of the photosensitive belt 511, is charged, and is reflected by the polarization beam splitter BS2 scanned by the rotating polygon mirror 13. The second system laser beam L2 overlaps with the arrival of the image of the yellow (Y) toner to form a latent image PM,
Subsequently, the latent image is developed by the developing sleeve 532 of magenta (M) toner.

After that, latent images of cyan (C) and black (K) are formed and developed by the third and fourth laser beams L3 and L4 by the same means as described above.

When the development of the black (K) toner by the developing sleeve 534 is completed, a full-color image with four color toners of yellow (Y), magenta (M), cyan (C), and black (K) is formed on the photosensitive belt 511. Therefore, a full-color image can be formed in a short time.

As described above, in the laser beam scanning device of the present invention, the first imaging optical system on the front side of the polygon mirror has the polarization direction or wavelength of the light of the laser beam light source, or the combination of the polarization direction and the wavelength. It is composed of a plurality of image forming optical systems which are different and each have a cylindrical lens capable of guiding the laser beam to the polygon mirror.

The respective laser beam sources are individually adjusted together with the individual cylindrical lenses 12 so that an image is formed at a predetermined position on the photosensitive belt 511. Further, the beam splitters BS1, BS2 and BS3 are further adjusted. ,
This image adjustment is performed including the adjustment of the mirror M.

In this embodiment, as described above, the wavelength is 830n.
The first system laser beam L1 modulated by a color signal for yellow (Y) development with m and P polarized light, wavelength 83
Laser beam L2 of the second system modulated by a color signal for magenta (M) development with 0 nm and S polarization, wavelength
Laser beam L3 of the third system modulated by a color signal for developing cyan (C) with S polarization at 670 nm, wavelength
There are two types of wavelengths and polarization directions of the laser beam L4 of the fourth system modulated by the color signal for developing black (K) with 670 nm and P-polarized light. It has various types of laser beam imaging optics and enables full-color image formation.

As described above, in the laser beam scanning device according to the present method, it is possible to arbitrarily set the desired number of image forming optical systems in the first image forming optical system by the combination of the wavelength and the polarization direction. Unlike the conventional example, an expensive beam splitter for further combining the laser beams into one is unnecessary, and a very delicate and difficult unstable adjustment work for combining the laser beams into one laser beam is also unnecessary.

[0054]

According to the present invention, it is possible to stably form a high-quality full-color image in a short time by using any desired number of individual laser beams. The structure is simple and the number of parts is small as compared with the conventional one. A low cost, compact laser beam scanning device has been provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a laser beam scanning device according to the present invention.

FIG. 2 is a diagram for explaining a situation where a laser beam is reflected and transmitted by a beam splitter and a mirror depending on the polarization direction and wavelength of light.

FIG. 3 is a side view of a conventional laser beam scanning device.

FIG. 4 is a perspective view of another conventional laser beam scanning device.

FIG. 5 is a perspective view of another conventional laser beam scanning device.

[Explanation of symbols]

 1 First Imaging Optical System 110 Laser Beam Emitting Units 111, 112, 113, 114 Laser Light Sources 12, 15 Cylindrical Lens 13 Polygon Mirror 14 fθ Lens 2 Second Imaging Optical System 30 Index Sensor 511 Photosensitive Belt 521, 522, 523, 524 Charger 531, 532, 533, 534 Development sleeve L, L1, L2, L3, L4 Laser beam BS1, BS2, BS3 Beam splitter M Mirror

Claims (2)

[Claims] 1. A first imaging optical system on the front side of the polygon mirror including a cylindrical lens for forming an image of the laser beam on the polygon mirror, and the laser beam on an imaging position on the rear side of the polygon mirror. In a laser beam scanning device having a second image forming optical system including a cylindrical lens for forming an image, the first image forming optical system is arranged such that the first image forming optical system mutually polarizes the light of the laser beam light source, or has a wavelength, or a polarization direction and a wavelength. 2. A laser beam scanning device comprising a plurality of imaging optical systems each having a different combination and having a cylindrical lens capable of guiding the laser beam to a polygon mirror. 2. The first imaging optical system has two kinds of polarization directions and wavelengths of light from the laser beam light source, and has four kinds of laser beam imaging optical systems depending on combinations of polarization directions and wavelengths. The laser beam scanning device according to claim 1, wherein: