JPS61261714A - Laser scanner - Google Patents

Abstract

PURPOSE:To shorten the rising time of a synchronous detection signal and to improve the accuracy of a synchronizing signal by arranging a slit plate so that a laser beam passing the slit plate irradiates only the first half scanning of a sensor part of a synchronous detector. CONSTITUTION:An optical synchronous detection signal is obtained from an incident laser beam 16. A laser beam 17 to be a stray light when irradiating the latter half of the optical synchronous detector 13 is interrupted by the slit plate 15. Since the slit plate 15 is parallel with the scanning surface of a photosensitive body 14, the laser beam 17 is reflected in the direction 18 preventing the laser beam 17 from irradiating the photosensitive body 14. Namely, the laser beam passing the slit plate 15 irradiates only the first half scanning of the sensor of the synchronous detector and the laser beam interrupted by the slit plate 15 is arranged in the direction preventing the laser beam from irradiating the photosensitive body, so that stray light to be irradiated to the photosensitive body is removed and the laser scanner can be prevented from the generation of black stripes.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a laser scanning device that records an image by deflecting and scanning a laser beam onto a photoreceptor.

2. Description of the Related Art In recent years, laser scanning devices have been widely used in laser printers and the like.

An example of the conventional laser scanning device mentioned above will be described below with reference to the drawings.

FIG. 4 shows a schematic configuration diagram of a conventional laser scanning device. In FIG. 4, 31 is a laser light source, 32 is a polygon deflector, 33 is an optical synchronous detector, and 34 is a photoreceptor.

Regarding the conventional laser scanning device configured as described above,
The operation will be explained below.

First, a laser beam emitted from a laser light source 31 is deflected and scanned on a photoreceptor 34'' by a polygon deflector 32. 33
is an optical synchronous detector that detects the position of the deflected laser beam. When the laser beam is incident on this optical synchronous detector 33, a synchronous detection signal is obtained, and the recording position of the image can be determined.

The optical synchronization detector 33 is arranged parallel to the laser scanning section of the photoreceptor 34 at the end where the scanning of the laser beam begins.

Problems to be Solved by the Invention However, in the above configuration, since the optical synchronous detector 33 is arranged at an angle with respect to the incident laser beam, the incident laser beam is irradiated with a wide spot diameter in the scanning direction. . Figure 6 shows the state of the laser beam at this time.

FIG. 6a shows when the incident laser beam 36 is incident at an angle,
The figure shows the state in which the scanning laser spot 37 is incident on the sensor 38 of the optical synchronous detector 36, and the figure C shows the rising state of the detection signal at this time. As shown in FIG. 6, since the scanning laser spot 37 spreads in the scanning direction, the rise time of the detection signal becomes longer and the accuracy of position detection deteriorates.

In order to solve these drawbacks, there has been a method of arranging the optical synchronous detector so that it hits the incident laser beam at right angles. Figure 6 shows a schematic configuration diagram of a laser scanning device in which an optical synchronous detector is arranged perpendicular to the incident laser beam.
The figure shows a diagram explaining the state of the detection signal at that time. 6th
In the figure, the laser beam 4o is incident on the optical synchronous detector 43 at right angles (FIG. 7a). At this time, the laser spot 47 has the smallest diameter and enters the sensor 48 (see figure b).
, the rise of the detection signal becomes faster (C in the same figure). However, in this case, a part of the laser light incident on the optical synchronous detector 43 is reflected by the metal part of the optical synchronous detector 43 and the sensor,
There is a problem in that the photoreceptor 44 is irradiated with stray light. In FIG. 6, the laser beam 46 incident on the front half of the optical synchronous detector 43 does not hit the photoreceptor 44, but the laser beam 46a incident on the rear half
It is reflected by the optical synchronous detector 43 from the angle shown in the figure, hits the polygon deflector 42 again (4eb), and is reflected (46C).
, the photoreceptor 44 is irradiated with stray light, resulting in black lines and the like appearing on the image.

In view of the above problems, the present invention shortens the rise time of the signal of the optical synchronous detector, and prevents the laser beam reflected by the optical synchronous detector from becoming stray light and irradiating the photoreceptor. We also provide laser scanning equipment1
6.

It is the rent.

】 The only way to solve the problem
In order to solve the above problems, the laser scanning of the present invention
The scanning device includes an optical synchronous detector placed perpendicular to the incident laser beam, and a 16-coil detector in front of the optical synchronous detector. picture. #'t'fTKl
effg 9. It is constructed such that the laser beam passing through the slit plate illuminates only the front half of the scan of the sensor section of the optical synchronous detector. be.

Operation j The present invention has the above-mentioned configuration, in which a detection signal is obtained in the front half of the sensor of the optical synchronous detector ( ), and the laser beam that is a foil in the rear half is transmitted through a slit. Since it is blocked by a plate, it is possible to eliminate stray light and laser light that irradiates the photoreceptor.

・,1'1 5, :1 Example, 1.1 Regarding the laser scanning device of one embodiment of the present invention 1,! This will be explained with reference to the drawings. FIGS. 1a and 1b show a schematic configuration diagram and a plan view of a laser scanning device according to a first embodiment of the present invention. In Figure 1, 6 to 11 is a laser light source, 12 is a polygon deflector, and 13 is a laser light source.
1 is an optical synchronous detector, 14 is a photoreceptor, and 16 is a slit plate.

The operation of the laser scanning device configured as described above will be described below with reference to FIGS. 1 and 2. In FIG. 1, an optical synchronous detector 13 is
Since they are orthogonal, a synchronization detection signal with a fast rise can be obtained. The laser beam 17 that hits the rear half of the optical synchronous detector 13 and becomes stray light is blocked by the slit plate 16. Since the slit plate 16 is parallel to the scanning surface of the photoreceptor 14,
Direction 1 that does not hit the body 14 depending on the angle of the first figure
reflected to 8. FIG. 2 shows the positions of the slit plate 26 and the sensor 22 of the optical synchronous detector 23 as seen from the incident laser beam side. The laser beam is made to shine only on the front half of the sensor 22 through the slit 21 of the slit plate 25.

As described above, according to this embodiment, the laser beam passing through the slit plate irradiates only the front half of the scan of the sensor of the synchronous detector, and the laser beam blocked by the slit plate irradiates the photoreceptor. Since the photoreceptor is arranged in a direction that does not interfere with the photoreceptor, it is possible to eliminate stray light from entering the photoreceptor and prevent the occurrence of black streaks.

A second embodiment of the present invention will be described below with reference to the drawings.

FIGS. 3a and 3b are a schematic configuration diagram and a plan view of a laser scanning device showing a second embodiment of the present invention. In the same figure, 1
2 is a laser light source, 2 is a polygon deflector, 3 is an optical synchronous detector, and 4 is a photoreceptor, which is the same as the configuration shown in FIG. 1. What is different from the configuration shown in Fig. 1 is that there is no slit plate, and the optical synchronous detector 3 is viewed from the horizontal direction of the scanning plane (the first
In Figure a), it is arranged at an angle from a right angle. In this way, the laser beam 6 incident on the optical synchronous detector 3 is reflected and returns to the polygon deflector 2, but since the optical synchronous detector 3 is disposed at a right angle to the incident laser beam, The reflected laser beam 6 does not hit the polygon deflector 2.

As shown in Fig. 1a, the optical synchronous detector 3 is placed at right angles to the incident laser beam when viewed from above the scanning plane (Fig. 3b), and at right angles when viewed from the side of the scanning plane. (Figure 3a)
), it is possible to prevent stray light from hitting the photoreceptor 4.

Effects of the Invention As described above, in the present invention, a slit plate is arranged parallel to the scanning surface on the photoreceptor in front of the optical synchronous detector orthogonal to the incident laser beam, and the incident laser beam passing through the slit plate is By providing a slit that scans and irradiates only the front half of the sensor section of the optical synchronization detector, the rise time of the synchronization detection signal is shortened, improving the accuracy of the synchronization signal, and the laser reflected by the optical synchronization sensor is It is possible to prevent the occurrence of stray light from the beam and eliminate the occurrence of black lines on images.

[Brief explanation of drawings]

FIGS. 1a and 1b are a schematic configuration diagram and a plan view of a laser scanning device according to a first embodiment of the present invention, FIG. 2 is a diagram showing the arrangement of the slit plate in FIG. 1, and FIG. 3a is a diagram. b is a schematic configuration diagram and a plan view of a laser scanning device according to the second embodiment of the present invention, FIG. 4 is a schematic configuration diagram of a conventional laser scanning device, and FIG. 5 is a diagram showing the rise of a detection signal of an optical synchronous detector. Figure 6 shows the state of reflection of the incident laser beam by the optical synchronous detector, and Figure 7 shows the rising state of the detection signal when the laser beam is perpendicularly incident on the optical synchronous detector. FIG. 1.11, 31.41 ・Laser light source, 2, 12
゜32.42 ... Polygon deflector, 3, 13, 33
゜43°・Optical synchronous detector, 4, 14, 34.44...
・Photoreceptor, 15...slit plate. Name of agent: Patent attorney Toshio Nakao and 1 other person
− Qi Kuichi What about smoke? uncle's oath
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Member 4 also

Claims (2)

[Claims] (1) An optical synchronous detector arranged perpendicularly to the incident direction of the laser beam at the end of the deflection scanning where the laser beam is deflected and scanned onto the photoreceptor, and in front of the optical synchronous detector. and a slit plate disposed parallel to the scanning surface on the photoconductor, and the slit plate is arranged so that the laser beam passing through the slit plate irradiates only the front half of the scan of the sensor section of the optical synchronous detector. A laser scanning device characterized by having plates arranged. (2) Claim 1, characterized in that the optical synchronous detector is disposed at a right angle to the laser beam when viewed from above the scanning surface and inclined from the right angle when viewed from the lateral direction of the scanning surface. The laser scanning device described.