JPH0456819A - Photodetector - Google Patents

Abstract

PURPOSE:To fix a reflection mirror so that its angle can be adjusted without reducing its function and fixing accuracy by unitedly molding a holding member for holding the reflection mirror and the mirror and covering the side of the mirror with the holding member. CONSTITUTION:The glass-made reflection mirror 20 is fixed on the inside face of the holding member 21 consisting of an approximately L shape synthetic resin member by united molding and the member 21 holds the mirror 20 approximately vertically to a frame 50. A pin 21a is vertically projected on the face of the member 21 contacting with a frame 5 and the member 21 can be rotated around the pin 21a in the horizontal direction. The mirror 20 is covered with the member 21 up to its side face. Consequently, the angular accuracy of the mirror 7 can be improved and troubles such as whitening and cracking to be generated at the time of fixing the mirror 20 can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photodetection device that is installed in a scanning optical device in an image forming apparatus and generates a horizontal synchronization signal.

[Prior Art] In a scanning optical device in which a light beam emitted from a light source is deflected and scanned by a rotating polygon mirror, there is a surface division error on each surface of the rotating polygon mirror, so it is difficult to obtain a horizontal synchronization signal in the scanning direction. A detection device is required.

FIG. 5 shows a configuration diagram of a scanning optical device, and a light beam L emitted from a light source device 1 containing a semiconductor laser light source is
The scanning light is converted into scanning light by a rotating polygon mirror 2 that is rotated at high speed in the direction of the arrow by a drive motor, passes through an imaging lens group 3 having f/θ characteristics, and is focused on the surface of a photoreceptor drum 4.
A recorded image is formed in the direction of the arrow. The frame 5 positions and fixes each of these members with high precision, and the frame 5 includes a light detection means 6 and a reflection mirror 7. This reflecting mirror 7 is for reflecting the light beam L° on the non-image area and the image writing side and guiding it to the light detecting means 6, and is fixed to the holding member 8 by press fitting or with an adhesive.

A photodetection means 6 for detecting the light beam L° reflected by the reflecting mirror 7 includes a photoelectric conversion element 9 that receives the light beam L' and generates an electric signal, and a photoelectric conversion element 9 disposed in front of this element 9. It consists of a slit 10 and a correction lens 11 for preventing detection failures due to mounting errors of the reflecting mirror 7. A horizontal synchronization signal for the recorded image is obtained by the light detection means 6, and the holding member 8 is further provided with an adjustment mechanism for forming the image at a desired position.

That is, as shown in FIG. 6(a), a bin 12 disposed substantially below the reflecting mirror 7 is engaged with the optical frame 5, and the holding member 8, that is, the reflecting mirror 7 is held around the bin 12 as a fulcrum. As shown in FIG. 6(b), it is rotatable in the horizontal direction indicated by the arrow. Thereby, the direction of the light beam L° passing through the slit 10 and reaching the photoelectric conversion element 9 can be changed, and the timing of recording an image can be adjusted.

[Problems to be Solved by the Invention] However, when fixing the reflecting mirror 7 to the holding member 8, there are the following problems.

(11 When fixing the reflecting mirror 7 by press-fitting or fitting it into the holding member 8, the reflecting mirror 7 is likely to be chipped. Also, when the holding member 8 is a molded part made of a synthetic resin material, , when press-fitting the reflecting mirror 7 into the holding member 8, the synthetic resin material is scraped, causing play in the installation, increasing the installation error of the reflecting mirror 7, and making it easier to detect the light beam L°. .

(2) In the method of fixing the reflective mirror 7 to the holding member 8 with adhesive, a quick-acting moisture adhesive is generally used from the viewpoint of efficiency in assembly work, but this adhesive does not evaporate with steam. There is a problem in that whitening occurs easily on the reflective surface. In addition, when the reflective surface of the reflective mirror 7 and the adhesive surface are different, the accuracy of the mounting angle of the reflective surface depends on the parallelism of the reflective mirror 7, and it becomes necessary to control parallelism with high precision, which increases costs. It can also be used as a close-up.

(3) As shown in FIG.
from the front with the holding member 13, and then tighten the screw 14.
The fixing method requires many components, complicates the work, and increases costs. Furthermore, in this configuration, since the light beam L° for obtaining the horizontal synchronization signal and the light beam L" for the image effective area are close to each other, the protrusion of the pressing member 13 will also obstruct the light beam L", which is preferable. It's not the composition.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a photodetecting device in which a reflecting mirror can be fixed in an adjustable manner without deteriorating its function or mounting accuracy.

[Means for Solving the Problems] In order to achieve the above-mentioned object, in a photodetecting device according to the present invention, the photodetecting device generates a synchronization signal by a part of the scanning light deflected by a reflecting mirror. A holding member for holding a reflecting mirror and the reflecting mirror are integrally molded, and a side surface of the reflecting mirror is covered with the holding member.

[Function 1] The photodetector having the above-mentioned configuration has the reflecting mirror and its holding member integrally molded, so that the performance of the reflecting mirror is not impaired (it can be easily and securely fixed to the holding member, and the side surface of the reflecting mirror can be easily and securely fixed to the holding member. By covering with a holding member, diffused reflection on the side surface is prevented.

[Example] The present invention will be explained in detail based on the example illustrated in FIGS. 1 to 4. Note that the same reference numerals as in FIG. 5 indicate the same members.

FIG. 1 shows a perspective view of the vicinity of the reflection mirror of the photodetector according to the first embodiment, in which a reflection mirror 20 made of glass is integrated with the inner surface of a holding member 21 made of an abbreviated synthetic resin material. Fixed by molding, this holding member 21 holds the reflecting mirror 2o substantially perpendicular to the frame 5. A bottle 21a is vertically projected from the surface of the holding member 21 in contact with the frame 5, and its position is substantially below the reflecting mirror 2o. As shown in FIG. 2, this bottle 21a is
It is engaged with a fitting hole on the optical frame 5, and the holding member 21 is horizontally rotatable about the bin 21a. Further, the holding member 21 is configured to surround the side surface of the reflecting mirror 20, and the bottle 21a is also molded at the same time using a material with a small coefficient of linear expansion. Also,
As shown in FIG. 2, it is preferable to provide an escape hole 21b on the back side of the reflective mirror 20 of the holding member 21 so as to absorb deformation due to thermal expansion of the holding member 21.

In this embodiment, the reflection mirror 2o can be rotated to form an image from a desired position. In addition, since the reflecting mirror 2o is fixed to the holding member 21 without press-fitting, fitting, or gluing, there is no possibility of damaging the reflecting mirror 20 or making the fixing incomplete, as seen in conventional methods, and the screw The work does not become complicated like fixing by. Furthermore, since the holding member 21 is integrally molded with the reflecting mirror 20, it is no longer necessary to manage the dimensional accuracy of the back surface of the reflecting mirror 2o and the reflecting mirror fixing surface of the holding member 21, which was essential in the past, and the fixation becomes strong. In addition, since the side surface of the reflective mirror 2o is covered with the holding member 21, when light hits the side surface of the reflective mirror 20,
It is also possible to prevent the occurrence of diffused reflection, which exposes the photosensitive drum and stains the image. Moreover, in this case, the thickness covering the side surfaces can be made thinner than in the conventional case, so there is less risk of blocking the light beam L'' in the image effective area.Also, by using a material with a small coefficient of linear expansion, Glass and synthetic resin expand with changes in ambient temperature, making it difficult for the glass to become distorted due to the difference in their expansion coefficients.

Furthermore, in the embodiment of the present invention, an aluminum material mirror-finished and coated with an anti-oxidation protective film is used, and the holding member 21 has a coefficient of thermal expansion (2, 3
It is more preferable to use a synthetic resin material having a coefficient of thermal expansion equivalent to X 10-'/''C). This is because the distortion of the reflecting mirror 20 can be reduced and the accuracy of the photodetecting device can be improved. That is, when using the reflecting mirror 20 made of glass,
It was necessary to make the reflective mirror 20 thick in order to prevent cracks from occurring during molding, but since aluminum does not crack, it can be made thinner, resulting in smaller size and lower costs.Another reason is that the image forming apparatus is At this time, if the thermal expansion coefficients of the reflecting mirror 20 and the holding member 21 are large (different), distortion will occur in the reflecting mirror 20, and the reflected light beam L will be distorted.

Since the shape of the photoelectric conversion element 9 is distorted, the output of the photoelectric conversion element 9 is deformed.
There is a problem in obtaining the horizontal synchronization signal. Therefore, by using an aluminum material, which has a coefficient of thermal expansion larger than that of glass and close to that of a synthetic resin material, for the reflecting mirror 20, it becomes easy to match the coefficients of thermal expansion of the reflecting mirror 20 and the holding member 21. Therefore, the distortion of the reflecting mirror 20 can be made extremely small.

FIG. 3 shows a cross-sectional view of the second embodiment, in which the reflecting mirror 20
It has an adjustment mechanism that absorbs installation angle errors. The bottom part of an L-shaped elastic member 22 made of a metal leaf spring or the like is fixed by a pin 5a protruding from the frame 5, and the upright part of this elastic member 22 is combined with a reflecting mirror 20 made of aluminum material. Holding member 23 made of resin material
The angle can be adjusted by biasing the holding member 23 from the rear with a feed screw 24.

Further, the bin 5a is used as a fulcrum when adjusting the timing of recording an image. When the distance from the reflecting mirror 20 to the light detecting means 6 is long, the angle accuracy may not be satisfied even if the reflecting mirror 20 and the holding member 23 are integrally molded. The angle can be adjusted.

FIG. 4 shows a sectional view of the third embodiment. In addition to the second embodiment, the bottom part of the elastic member 22 is covered with a fixing member 25 made of synthetic resin, and the bottle 25a is covered with a fixing member 25. 25 and inserted into the frame 5. Furthermore,
After adjusting the timing, the elastic member 22 is fixed by the fixing screw 26.
and the fixing member 25 are fixed to the frame 5. As a result, the flatness of the surface in contact with the frame 5 is improved, and when attached to the frame 5 with the fixing screws 26,
Since the elastic member 22 does not bend, there is an effect that accuracy is not deteriorated and reinforcement is achieved.

[Effects of the Invention] As explained above, the photodetection device according to the present invention includes a reflection mirror that guides a light beam to the photodetection means in order to generate a horizontal synchronization signal, and a holding member that holds this reflection mirror. By integrally molding, it is possible to improve the angular accuracy of the reflecting mirror and to solve problems such as whitening and chipping when fixing the reflecting mirror, thereby simplifying the structure and reducing costs.

[Brief explanation of the drawing]

Drawings 1 to 4 show an embodiment of a photodetection device according to the present invention, in which FIG. 1 is a perspective view of the first embodiment, FIG. 2 is a partially cutaway front view, and FIG. 3 is a partially cutaway front view. is a sectional view of the second embodiment, FIG. 4 is a sectional view of the third embodiment, FIG. 5 is a configuration diagram of a general scanning optical device, and FIG. 6 is a diagram of a conventional reflecting mirror. FIG. 7, which is an explanatory diagram of the adjustment method, is a perspective view of a conventional reflecting mirror. 5 is a frame, 20 is a mirror, 21.23 is a holding member, 21a and 25a are bottles, 21b is an escape hole, 22 is an elastic member, and a fixing member.

Claims (1)

[Scope of Claims] 1. In a photodetecting device that generates a synchronizing signal by a part of scanning light deflected by a reflecting mirror, a holding member that holds the reflecting mirror and the reflecting mirror are integrally molded, and the A photodetecting device characterized in that a side surface of a reflecting mirror is covered with the holding member. 2. The photodetecting device according to claim 1, wherein the reflecting mirror is a mirror member made of metal.