JPH0563775B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical scanning device in which an optical box is sealed with a cover.

[Conventional technology]

Generally, as shown in FIG. 1, in an optical scanning device 1 of an image forming apparatus, a rotating polygon mirror 2, which is a laser beam deflector, must be sealed to prevent surface deterioration, particularly a decrease in reflectance. It won't happen.

Conventionally, the optical scanning device 1 has a long optical path length to the photosensitive drum 3, which is an image bearing member, and the rotating polygon mirror 2 alone is not enough to use the imaging lens 4 having f-θ characteristics or the imaging lens 4 for determining the writing position of the laser beam. Detection mirror 5 for horizontal synchronization signal detection and photodetector 6
The entire mechanism including the structure is sealed (see, for example, Japanese Patent Application Laid-open No. 118145/1983, which will be described later).

JP-A-53-118145 discloses a laser transmitter as a light source, a rotating mirror that deflects the light beam emitted from the laser transmitter, and a photocon drum ( A configuration of an optical box is disclosed in which a condenser lens that forms an image on a photoreceptor is sealed with a cover fixed to a base.

[Problem that the invention seeks to solve]

However, in the conventional technology described above, since the optical box is provided with only one hole through which the laser beam passes, when the relative arrangement of the optical scanning device and the photoreceptor is changed, the optical box and the photoreceptor are There is a problem that there is no degree of freedom regarding the arrangement, the optical axis must be adjusted which takes a long time, and the design of the device is also difficult. Moreover, when changing the emission position of the laser beam, it is necessary to prepare a large-scale separate member, which makes the apparatus complicated.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to easily increase the degree of freedom regarding the arrangement of the optical box and the photoreceptor even when changing the relative arrangement of the optical scanning device and the photoreceptor. An object of the present invention is to provide an optical scanning device which has a simple configuration, can achieve and increase a dustproof effect, and does not require optical axis adjustment.

[Means for solving problems]

To achieve the above object, the present invention includes a light source that emits a laser beam, a deflection device that deflects the laser beam that is emitted from the light source, and an image of the laser beam that is deflected by the deflection device on a photoreceptor. an optical scanning device in which a lens is housed in an optical box and sealed with an exterior cover, the optical box having a first passage part and a second passage part through which a laser beam can pass; When the laser beam is emitted from the first passage section, the first passage section is provided with a transparent member and the second passage section is provided with a cover, and when the laser beam is emitted from the second passage section, the first passage section is provided with the above-mentioned transparent member. The present invention is characterized in that the cover provided on the second passage section and the transparent member provided on the first passage section are provided on the second passage section.

[Effect]

In the present invention configured as described above, when it is desired to emit a laser beam from the first passage section, the first
A transparent member is provided in the second passage portion, and a cover is provided in the second passage portion. When changing the relative arrangement of the optical scanning device and the photoconductor, in order to emit the laser beam from the second passage part, a laser beam is provided in the first passage part and in the second passage part. The transparent member provided in the first passage section is provided on the second passage section.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a perspective view of main parts of an image forming apparatus equipped with an embodiment of the optical scanning device of the present invention, and FIG.
FIG. 3 is a cross-sectional view of the embodiment shown in the figure, showing a state in which the laser beam is emitted from the first laser beam passage hole;
The figure is an enlarged partial cross-sectional view of the vicinity of the horizontal synchronizing signal means constituting the optical scanning device of FIG. 2, FIG. 5 is an enlarged partial front view of the horizontal synchronizing signal generating means of FIG. 4, and FIG.
This figure is similar to FIG. 3, and shows a state in which the laser beam is emitted from the second laser beam passage hole.

As shown in FIGS. 2 and 3, the semiconductor laser unit 11 of the optical scanning device 1' is a light source that irradiates and generates laser light, and it receives recording information signals from computers, word processors, facsimile transmitters, etc. This is a small light source device that consists of a semiconductor laser that is modulated and driven in accordance with the laser beam, and a shaping optical system that corrects the cross section of the laser beam from the semiconductor laser and converts the laser beam into a parallel beam. The rotating polygon mirror 2 is
It is a deflection means for scanning the laser beam irradiated from the semiconductor laser unit 11, and includes an imaging lens 4a,
4b and 4c are photosensitive drums 3 as photosensitive bodies that transmit laser light irradiated from the semiconductor laser unit 11;
It forms an image. This photosensitive drum 3 is located on the side of an optical box 17, which will be described later. The detection mirror 5 is a mirror that reflects the laser beam scanned by the rotating polygon mirror 2 to the horizontal synchronization signal detection position immediately before the laser beam scans the image forming area of the photosensitive drum 3. An entrance opening is arranged at a position where the light forms an image. The imaging lenses 4a, 4b, and 4c are, as disclosed in Japanese Patent Laid-Open No. 57-144514, an imaging lens 4a (cylindrical and imaging lenses 4b and 4c (spherical lens, torlic lens) that form an image of the deflected laser beam on the surface of the photosensitive drum 3 and scan it at a constant speed. With such a simple and compact configuration, the inclination of the deflection/reflection surface of the rotating polygon mirror 2 can be corrected.

The optical box 17 includes a bottom surface 17a having a desired shape and a side plate 17 disposed approximately perpendicularly to the side of the bottom surface 17a.
b, and includes various parts such as the semiconductor laser unit 11. The protective glass 18 as a transparent member is disposed on the side plate 17b of the optical box 17 near the photosensitive drum 3, and is used to transmit laser light and carry an image on the photosensitive drum 3. The optical box 17 is made of materials such as glass fiber and reinforced polycarbonate resin, and is precisely molded with high precision. The optical box 17 has a positioning pin 43 formed on the lower surface of the bottom surface 17a.
is fitted into a positioning hole (not shown) of the base 1a, so that the optical box 17 is positioned with high precision with respect to the photosensitive drum 3 and is detachably disposed.
The imaging lenses 4a, 4b, 4c and the detection mirror 5 are positioned on a mounting seat 17c formed on the upper surface of the bottom surface 17a of the optical box 17, and are arranged and fixed by adhesive or a fixing member (not shown). Ru. The slit plate 19 connects the protective glass 18 to the optical box 1.
The laser beam passes through the slit of this slit plate 19 towards the photosensitive drum 3. The exterior cover 20 of the box covers and seals the top surface of the optical box 17, and the hole cover 21 covers a second laser beam passage hole 26, which will be described later.

As shown in FIGS. 4 and 5, the optical fiber tube 15 for horizontal synchronization signal detection is mounted on mounting seats 31 and 3 disposed on the bottom surface 17a of the optical box 17.
The optical fiber tube 15 is positioned on the surface of a sharp edge 33 that covers about 1/3 of the cross section of the optical fiber tube 15, and is installed and fixed by the fixing plate 23 without adjustment. That is, the fixing plate 23 is for fixing the optical fiber tube 15 to the mounting seat 31. The drive motor 22 rotationally drives the rotating polygon mirror 2 . The sealing member 24 is fitted between the optical box 17 and the optical fiber tube 15, and serves to protect the inside of the optical box 17 from dust. The first and second laser beam passage holes 25 and 26 are a first passage part and a second passage part formed in the side plate 17b and the bottom surface 17a of the optical box 17, respectively, and allow the laser beam to reach the photosensitive drum 3. This is the hole through which it passes. In this embodiment, the optical fiber tube 15 is fitted to the optical box 17 via the sealing member 24, but may be fitted without using the sealing member 24.

Next, the operation of this embodiment will be explained.

As shown in FIGS. 2 to 5, the laser beam irradiated from the semiconductor laser unit 11 is irradiated and reflected by the reflecting surface of the rotating polygon mirror 2 rotating in the direction of arrow A via the imaging lens 4a. Ru. This reflected laser light is first irradiated and reflected by the detection mirror 5, and scans the vicinity of the center of the cross section of the entrance of the optical fiber tube 15 almost horizontally. The laser light incident and transmitted through the optical fiber tube 15 is photoelectrically converted by the photodiode 34 and converted into a horizontal synchronizing signal. When the semiconductor laser unit 11 is started to be driven using the recorded information signal after a predetermined period of time has elapsed since the detection of this horizontal synchronization signal, the photosensitive drum 3
A laser beam modulated in accordance with the information signal starts scanning from a predetermined position above. As a result, an electrostatic latent image is formed on the photosensitive drum 3. Note that well-known electrophotographic processing equipment is arranged along the rotation path of the photosensitive drum 3.

As explained above, in this embodiment, since the optical box is handled as an optical box unit during assembly and maintenance during production, there is no need for optical axis adjustment, and the handling is easy. In addition, the parts inside the optical box are not contaminated with dust and dust in the air, and the fingers do not touch them and cause finger diaphragm, so the detection accuracy of the horizontal synchronization signal does not deteriorate, and the output image does not fluctuate. The detection accuracy of this horizontal synchronization signal, in other words the recording accuracy on the surface of the photosensitive drum, is also determined by the processing accuracy of the optical box, and the semiconductor laser unit and drive motor are fitted into the optical box. Therefore, since the mounting position accuracy is high, the optical accuracy is high.
Furthermore, since an optical fiber tube is used as the horizontal synchronization signal detection means, the horizontal synchronization signal is transmitted to the processing circuit in the form of a laser beam, thereby reducing the influence of electromagnetic waves and improving noise resistance.

As shown in FIG. 6, when the photoconductor 3 is relocated below the optical box 17,
In order to emit the laser beam from the laser beam passage hole 26, the hole cover 21 provided in the first laser beam passage hole 25 and the second laser beam passage hole 26 is
The protective glass 18 provided in the first laser beam passage hole 25 is provided in the second laser beam passage hole 26, and this protective glass 18 is supported by a slit plate 19. In addition, the refracting mirror 16 is moved to the refracting mirror seat 4.
Place it in 1. As a result, the laser beam is refracted downward by the refraction mirror 16, passes sequentially through the second laser beam passing hole 26 and the hole in the base 1a, and scans the laser beam in a direction perpendicular to the photosensitive drum 3. It is something that makes you The refracting mirror 16 is attached to the optical box 1
A refracting mirror seat 41 formed on the bottom surface 17a of 7,
42 with adhesive or a fixing member (not shown).

In this way, optical scanning devices in which the photosensitive drums 3 are disposed at different positions do not require optical axis adjustment, and
A dustproof effect is also achieved.

〔Effect of the invention〕

Since the present invention is configured as described above, the optical box is provided with two passage sections through which the laser beam passes, and by providing a transparent member on one of the two passage sections and a cover on the other, When changing the relative position of the optical scanning device and photoconductor, the degree of freedom regarding the placement of the optical box and photoconductor is increased, eliminating the need for optical axis adjustment, achieving a dustproof effect, and simplifying device design. Moreover, it is possible to change the emission position of the laser beam with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view of a conventional optical scanning device of an image forming apparatus, and FIG. 2 is a perspective view of essential parts of an image forming apparatus equipped with an embodiment of the optical scanning device of the present invention.
FIG. 3 is a sectional view of the embodiment shown in FIG. 2, showing a state in which the laser beam is emitted from the first laser beam passage hole, and FIG. 5 is a partially enlarged front view of the horizontal synchronizing signal generating means in FIG. 4; FIG. 6 is a diagram similar to FIG. 3; This shows a state in which the light is emitted from the light passage hole. 1, 1'... Optical scanning device, 1a... Base, 2
... Rotating polygon mirror (deflection means), 3 ... Photosensitive drum (photoreceptor), 4a, 4b, 4c ... Imaging lens, 5
...Detection mirror, 6...Photo detector, 1
DESCRIPTION OF SYMBOLS 1...Semiconductor laser unit, 15...Optical fiber tube, 16...Refraction mirror, 17...Optical box, 17a...Bottom surface, 17b...Side plate, 17c
...Mounting seat, 18...Protective glass (transparent member),
19...Slit plate, 20...Exterior cover, 21
... Hole cover, 22 ... Drive motor, 23 ... Fixed plate, 24 ... Seal member, 25 ... First laser beam passage hole, 26 ... Second laser beam passage hole, 3
1, 32...Mounting seat, 33...Sharp edge,
34...Photodiode, 41, 42...Refraction mirror seat, 43...Pin.

Claims (1)

[Claims] 1. A light source that emits a laser beam, a deflection device that deflects the laser beam that is emitted from the light source, and a lens that images the laser beam deflected by the deflection device on a photoreceptor. In an optical scanning device housed in an optical box and sealed with an exterior cover, the optical box has a first passage section and a second passage section through which the laser beam can pass, and the laser beam passes through the first passage section. When the laser beam is emitted, the first passage section is provided with a transparent member and the second passage section is provided with a cover, and when the laser beam is emitted from the second passage section, the first passage section is provided with the second passage section. An optical scanning device characterized in that a cover provided at the first passage section is provided, and a transparent member provided at the first passage section is provided at the second passage section.