JPS63138368A - Laser light controller - Google Patents

Abstract

PURPOSE:To form a light rack which is completely parallel to the axis of a photosensitive drum even if a laser beam itself is distorted by providing a thin and long slit which is parallel to the axis of the photosensitive drum and stops down the laser beam on the optical path extending from a laser beam scanner to the photosensitive drum. CONSTITUTION:The thin and long slit 11 which is parallel to the photosensitive drum axis and stops down the laser beam is provided on the optical path extending from the laser beam scanner 2 to the photosensitive drum 6. Consequently, even if the strain of the reflecting surface of the laser beam scanner, the inclination of an optical system, etc., are large to some extent, the light track of the laser beam reaching the surface of the photosensitive drum is controlled by the slit. Therefore, the light track is formed completely in parallel to the axis of the photosensitive drum and a beautiful image having no distortion is formed. Further, the slit 11 is made changeable to adjust the size of a fine spot formed on the surface of the photosensitive drum 6 and the roughness of the image optionally.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laser light control device for controlling the width of a laser beam, and particularly relates to a laser light control device suitable for use in a laser beam printer. .

BACKGROUND ART FIGS. 4 and 5 relate to a conventional optical device for a laser beam printer, with FIG. 4 being a plan view thereof and FIG. 5 being a side view thereof.

Such an optical device, as shown in FIGS. 4 and 5,
By irradiating the reflective surface 21 of a rotating polygon surface 1112 (laser beam scanner) called a polygon mirror or the like that rotates in the direction shown by the arrow X with a laser beam L1 as shown by the arrow from the laser beam St, the rotating reflective surface 2a is
The laser beam reflected by the laser beam is swung in a direction parallel to the plane of the paper in FIG. It forms a light trail, and at that time, by controlling the laser beam R1 on and off, a bright and dark dot pattern is formed.

Then, rotation of the rotating polygonal boundary 2 and the laser light source 1 are performed.
A two-dimensional image is formed on the surface of the photosensitive drum 6 in the form of a dot pattern by on/off control and further rotation of the photosensitive drum 6 in the direction shown by arrow Y.

In FIG. 4, the fθ lens 3 provided between the rotating polygon mirror 2 and the mirror 4 is known as a distortion correction optical system, and the It has the above linearity, that is, the function of keeping the dot spacing constant and concentrating the laser beam into a minute spot of dots.

FIG. 6 shows the above-mentioned light trace, and the oblique line shown is one minute spot D (dot) formed on the surface of the photosensitive drum 6, and the laser beam L1 is shown in FIG. This shows a state in which the minute spot D is moved in the direction of the axis Z of the photosensitive drum 6 shown by the dashed line by swinging it left and right and blinking it. As shown in the figure, each of these minute spots D is made to have a pitch smaller than the width l in the lateral direction of the minute spot D, so that they overlap slightly in the lateral direction, and - the pitch of the light trace for each round trip, That is, by making the feeding pitch of the photosensitive drum 6 slightly smaller than the width of the minute spot D in the vertical direction, and by making it somewhat even in the vertical direction, gaps between images are prevented.

Problems with the Prior Art In the laser optical device as described above, it is important to strictly maintain the parallelism of the light trace formed on the surface of the photosensitive drum 6 with respect to the axis of the photosensitive drum 6. This is extremely important in order to eliminate distortion in images.
In the conventional optical device for a laser beam printer as described above, the light trail is slightly bent due to, for example, the inclination of the fθ lens 3 or the distortion of the reflective surface 2a of the rotating polygon mirror 2.

Among these, the inclination of the fθ lens 3 can be corrected to some extent by adjusting the inclination of the mirror 4, for example, but the distortion due to the processing precision of the reflective surface 21 of the rotating polygon mirror 2 cannot be corrected by such measures It cannot be resolved by either.

OBJECTS OF THE INVENTION Accordingly, an object of the present invention is that even if there is some distortion in the reflective surface of the rotating polygon mirror used as a laser beam scanner, the lens group such as the rθ lens, the mirror, etc. Even if the laser beam itself is swung laterally with some degree of distortion, the laser beam can form an undistorted light trail on the surface of the photosensitive drum. The purpose of the present invention is to provide a control device.

Composition of the Invention In order to achieve the above object, the main means adopted by the present invention is that the main means adopted by the present invention is that the optical path from the laser beam scanner to the photosensitive drum is parallel to the axis of the photosensitive drum in order to focus the laser beam. This is a laser beam control device in which an elongated slit is provided.

The laser beam emitted from the working laser light source is reflected by the rotating laser beam scanner and reaches the surface of the photosensitive drum while spreading in a fan shape. At this time, slight distortion occurs in the laser light source due to distortion of the reflective surface of the laser beam scanner, lens groups, mirrors, etc. on the way, but in order to focus the laser beam on the optical path from the laser beam scanner to the photosensitive drum. Since a long and narrow slit is provided parallel to the axis of the photosensitive drum, even if the laser beam itself is distorted as described above, the laser beam that reaches the surface of the photosensitive drum is regulated by the shape of the slit, and the photosensitive drum is This creates a light trail perfectly parallel to the drum axis.

EMBODIMENT OF THE INVENTION Next, with reference to the attached drawings of FIGS. 1 to 3, embodiments embodying the present invention will be described to provide an understanding of the present invention.

Here, FIG. 1 is a schematic configuration diagram of a laser beam printer equipped with a laser beam control device according to an embodiment of the present invention, and FIG.
The figure is a side sectional view showing a slit mounting structure provided in the same laser beam printer, and FIG. 3 is a schematic plan view showing light traces on the surface of the photosensitive drum in this embodiment.

Note that the following example is only one specific example of the present invention, and is not intended to limit the technical scope of the present invention.

Further, the same reference numerals will be used to describe the same elements as those of the conventional optical device shown in FIGS. 4 and 5.

In FIG. 1, the laser beam emitted from the laser light source 1 hits the reflecting surface 2□ of the rotating polygon mirror 2, as shown by the dashed line, and is reflected radially within a plane perpendicular to the plane of the paper of FIG. After passing through the lens 3 and being reflected by the mirror 4, it passes through the cylindrical lens 5 and then the slit! Fi1
The light is narrowed by passing through a slit 11 shown in FIG.

FIG. 2 shows the mounting structure of the slit plate 10.
The slit plate 10 is a blocking plate 12 shown in FIGS. 1 and 2.
The slit plate 10 is fixed to a holder 14 attached to a mounting hole 13 formed in the slit plate 10, and the holder 14 is attached so that the slit plate 10 can be freely inserted and removed in a direction perpendicular to the plane of the paper shown in FIG.

As shown in FIGS. 2 and 3, a thin gold film 11' is laminated on the surface of the slit plate 10 by vapor deposition or the like, and the slits 11 of 1lliL0 are formed by etching or the like in a direction perpendicular to the plane of the paper in FIG. It is formed.

As shown in FIG. 2, the laser beam passes through the cylindrical lens 5, passes through a long hole 15 formed in the holder 14, is condensed by a slit 11 formed in the slit plate IO, and then passes through the photosensitive drum 6. reaching the surface.

As shown in FIG. 1, the shielding plate 12 includes a printer section 27 having a photosensitive drum 6 and the like, a rotating polygon mirror 2. fθ lens 3. Mirror 4. By partitioning the optical system chamber 28 having the cylindrical 5 and the like, the optical system chamber 28 is shielded from toner fine powder and silicon vapor generated in the printer section 27.

As mentioned above, by replacing the slit plate 10,
It is possible to use slits 11 having different widths.

Thereby, the size of the minute spot formed on the surface of the photosensitive drum 6 can be adjusted, and the roughness of the image grains can be adjusted.

Therefore, regarding the vertical width of the laser beam at the slit slope 100 portion shown in FIG. It is sufficient to adjust @L to such an extent that it does not come off from the slit 11, and if this width is set sufficiently large, the reflection surface 2□ of the rotating polygon mirror 2, which causes distortion of the laser beam, can be adjusted. Distortion and f
Even if the inclination of the θ lens 3 is large to some extent, no problem arises.

As described above, by exposing the surface of the photosensitive drum 6 with laser light, a two-dimensional electrostatic latent image is formed on the surface of the photosensitive drum as the photosensitive drum 6 rotates. When this passes through the developing section 16, it is developed into a toner image.

When this toner image passes through the transfer section 17, it is sent out from the cassette 18 by a paper feed roller 19 and is sent to a paper feed path 20.
The image is transferred onto the surface of the copy paper supplied to the transfer section 17 through the transfer section 17.

In this way, the copy paper on which the toner image has been transferred is sent by the conveyor belt 21 to the fixing section 22, where it is fixed.

The copy paper on which the toner image has been fixed is guided by a switching guide 23 and discharged onto a paper discharge tray 24, or passes through a paper discharge guide 25 and is discharged to a paper discharge section 26 at the top of the machine.

Effects of the Invention As described above, the present invention provides a method for focusing a laser beam on the optical path from the laser beam scanner to the photosensitive drum.
This laser beam control device is characterized by having a long and narrow slit parallel to the axis of the photosensitive drum, so even if the reflection surface of the laser beam scanner is distorted or the optical system is tilted to some extent, the photosensitive drum will not be affected. Since the light trail of the laser beam that reaches the surface of the photosensitive drum is regulated by the slit, it is formed completely parallel to the axis of the photosensitive drum, resulting in the formation of a beautiful image without distortion.

Note that by making the slit replaceable, the size of the minute spot formed on the surface of the photosensitive drum, that is, the roughness of the image, can be adjusted as desired.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a laser beam printer equipped with a laser beam control device according to an embodiment of the present invention, FIG. 2 is a side sectional view showing the mounting structure of a slit provided in the laser beam printer, and FIG. is a schematic plan view showing a light trace on the surface of a photosensitive drum in this embodiment, FIG. 4 is a plan view of an optical system in a conventional laser beam printer, FIG. 5 is a side view of the same, and FIG. FIG. 3 is a schematic plan view showing a light trace pattern on a photosensitive drum in the optical system of FIG. (Explanation of symbols) l... Laser light source 2... Rotating polygon vA (laser beam scanner) 21.
...Reflecting surface 3...Fθ lens 4...Mirror 5...Cylindrical lens 6...Photosensitive drum lO...Slit plate 11...
... Slit 12 ... Shielding plate 14 ... Holder 15 ... Long hole 27 ... Printer section 28
...Optics room. Figure 5 Figure 3 Figure 6

Claims (1)

[Scope of Claims] 1. A laser beam control device characterized in that an elongated slit parallel to the axis of the photosensitive drum is provided in the optical path from the laser beam scanner to the photosensitive drum for narrowing down the laser beam. 2. Claim 1 in which the slit is replaceable
The laser light control device described in Section 1.