JPH0320811Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) The invention is applicable to so-called laser printers that write images by deflecting and scanning a light-modulated laser beam,
Conversely, regarding an optical deflector used in a reading device etc. that reads an image by deflection scanning of a laser beam, more specifically, it has a rotating polygon mirror and a case covering the rotating polygon mirror, and the case has a The present invention relates to an optical deflector in which an opening (window) is formed.

(Prior Art) For example, in a laser printer, a rotating polygon mirror is generally used as a beam scanning means. When this rotating polygon mirror is used, its surroundings are covered with a case for reasons such as safety considerations and ease of handling. Figures 1 and 2 are
1 is a diagram showing an optical deflector having such a structure, FIG. 1 is a plan view, and FIG. 2 is a front view. In these figures, 1 is a rotating polygon mirror having a plurality of mirror surfaces 1a,
Reference numeral 2 denotes a case that covers the rotating polygon mirror 1, and 3 indicates a drive section in which a motor and the like for rotationally driving the rotating polygon mirror 1 are housed. The case 2 has an opening 2a for light passage. The thickness of the case 2 in this optical deflector is uniform over the entire circumference including the vicinity of the opening end 2b.

By the way, in this type of optical deflector, when the rotating polygon mirror 1 is rotated at high speed, wind is generated by the rotation, and wind noise is generated at the end of the opening 2a of the case 2. Conventionally, the following two countermeasures have been taken against this wind noise. One of them is
The purpose is to increase the inner diameter of the case 2 and increase the distance between the rotating polygon mirror 1 and the inner wall of the case 2. Another reason is to prevent wind noise from escaping the equipment.
This means taking soundproofing measures. However, these measures have the following drawbacks. That is, the former method has the drawback that the case 2 becomes larger, leading to an increase in the size of the equipment such as a laser printer, and the latter method leads to a considerable increase in cost.

(Purpose of the invention) The present invention has been made in view of the above-mentioned drawbacks, and its purpose is to realize an optical deflector that does not increase the size or cost of the device.

(Structure of the Device) The present invention that achieves this object is an optical deflector that includes a rotating polygon mirror and a case that covers the rotating polygon mirror, and the case is provided with an opening for light passage. The case is characterized in that a cross-section of the wall portion of the case on the side thereof is configured to have a tapered shape.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 3 is a sectional view (corresponding to the AA sectional view in FIG. 2) showing an embodiment of the present invention. In this figure, parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals, and their explanations will be omitted. The difference between this embodiment and the conventional example shown in FIGS. 1 and 2 is that the wall section of the case 2 on the side of the opening 2a is tapered. Therefore, the edge of the open end 2b becomes sharp, and the generation of wind noise is significantly reduced.

FIG. 4 is a sectional view (corresponding to the sectional view AA in FIG. 2) showing another embodiment of the present invention. In this figure as well, parts corresponding to those in FIGS. 1 and 2 are designated by the same reference numerals, and their explanations will be omitted. The difference between this embodiment and the conventional example shown in FIGS. 1 and 2 is that the opening angle θ (see FIG. ),
The point is chosen such that the inner wall surface 2c of the wall of the case 2 moves away from the rotating polygon mirror 1 as it approaches the opening end 2b. Therefore, the open end 2b has been moved outward compared to the conventional example, which essentially corresponds to increasing the inner diameter of the case 2. Therefore, wind noise is also significantly reduced. Of course, as a result of forming the opening 2a as described above, the edge of the opening end 2b also becomes sharp, similar to the embodiment shown in FIG. Therefore, from this point as well, generation of wind noise can be prevented. Furthermore, in terms of processing, it is a simple change in the shape of the case 2 and can be processed in the same manner as before, so there is no increase in costs.

Although FIG. 4 shows an embodiment in which the cut near the opening end 2b is a flat surface (the opening angle is constant), the invention is not limited to this. That is, case 2
If the inner wall surface 2c of the wall moves away from the rotating polygon mirror 1 as it approaches the opening end 2b,
The effect of preventing wind noise can be further improved. For example, the opening 2a may be formed so that the inner wall surface 2c portion expressed as a straight line in FIG. 4 described above becomes a broken line or a curved line. Further, if the case 2 has a small wall thickness, the shape of the inner wall surface 2c can be realized by bending.

(Effects of the Invention) As described above, according to the present invention, since the wall section of the case on the side of the opening is tapered, the generation of wind noise can be significantly reduced. Furthermore, since there is no need to increase the inner diameter of the case, the device does not become larger. Furthermore, since the processing can be performed using the same steps and processing techniques as conventional ones, there will be no increase in costs.

[Brief explanation of the drawing]

1 and 2 are diagrams showing an example of a conventional optical deflector, with FIG. 1 being a plan view and FIG. 2 being a front view. Further, FIGS. 3 and 4 are sectional views showing embodiments of the present invention, respectively. 1... Rotating polygon mirror, 1a... Mirror surface, 2... Case, 2a... Opening, 2b... Opening end, 2c...
Inner wall surface, 3... Drive section.

Claims (1)

[Claims for Utility Model Registration] (1) In an optical deflector comprising a rotating polygon mirror and a case covering the rotating polygon mirror, the case is provided with an opening for light passage; An optical deflector characterized in that the wall section of the case is configured to have a tapered shape. (2) Utility model registration claim 1, characterized in that the inner wall surface of the wall of the case on the side of the opening is formed so as to become farther away from the rotating polygon mirror as it approaches the opening end. Optical deflector as described in section. (3) Forming the opening in the case with a constant opening angle such that the distance between the rotating polygon mirror and the inner wall surface of the wall on the side of the opening of the case widens as it approaches the opening end. An optical deflector according to claim 2 of the utility model registration claim.