JPH10153744A - Silencer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an effective sound-proofing device for optical deflector, which has a simple constitution, causes no decrease in light utilization efficiency, and exerts no influence of shading and is low-cost. SOLUTION: At the light incidence and projection parts of an optical deflector which uses a rotary polygon mirror 4, shield members 22, 23, and 24, which have opening parts 22a, 23a, and 24a large enough to pass incident luminous flux L0 and pieces L1 to L2 of projection luminous flux are provided while isolated from one another. Noise is attenuated each time it passes through an opening of one shield member and then reduced to a small noise level finally.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silencer in various machines and devices, and more particularly to a silencer suitable for a rotary polygon mirror used in an optical deflector such as a laser writing unit.

[0002]

2. Description of the Related Art In recent years, the speed of optical deflectors, such as laser printers and laser facsimile machines, has been particularly increased, and the rotating polygon mirror used for this purpose rotates at a high speed of 10,000 or more revolutions per minute. When the rotating polygon mirror is rotated at such a high speed,
Wind noise during rotation increases, generating loud noise,
The periphery of the rotating polygon mirror is covered with a substantially cylindrical cover.

FIG. 7 illustrates the entirety of a general optical deflector. A laser beam L ₀ generated from a laser oscillator 2 mounted on an optical housing 1 is collected by a cylindrical lens 3 into a predetermined beam shape. After being illuminated, it is polarized and scanned by the rotating polygon mirror 4 in the range of L ₁ to L ₂ ,
An image is formed on the photosensitive drum 6 via the imaging lens system 5. Of the rotary polygon mirror 4 thus reflected laser beam from L ₁ L ₂
The light beam L ₃ outside the range of is introduced into the optical fiber 8 by the reflection mirror 7, it is converted to the scanning start signal.

FIG. 8 is a view showing the rotary polygon mirror 4 and its driving unit. The driving unit of the rotary polygon mirror 4 includes a rotating shaft 9, a rotor magnet 10 integrally connected to the rotating shaft 9, and a rotating shaft 9.
, A stator coil 12 integral with the bearing device 11, and a circuit board 13 for supplying a drive current to the stator coil 12. The rotary polygon mirror 4 is pressed against a flange member 9a that is integral with the rotary shaft 9 by a holding mechanism 15 including a wave washer 15a, a flat washer 15b, and a retaining ring 15c, thereby being integrated with the rotary shaft 9. . The rotary polygon mirror 4 is covered by a substantially cylindrical cover 16, which restricts the flow of air due to the rotation of the rotary polygon mirror 4, reduces wind noise, and reduces wind noise. To prevent leakage. The cylindrical portion 16a of the cover 16 has a window 17 through which laser light passes.
Is provided.

[0005]

However, in the above-mentioned prior art, since the laser beam enters and exits through one window 17 which is an opening provided in the cylindrical portion 16a of the cover 16, the opening area of the window 17 is increased. Has to be larger than a predetermined size, and there is a problem that there is a limitation in improving soundproofing and dustproofing effects.

[0006] In order to solve this problem, a product in which a glass plate is fitted into the window and the periphery of the rotary polygon mirror is sealed to perform soundproofing and dustproofing has been commercialized. However, the light transmittance of the sheet glass and its dependence on the incident angle cause a remarkable decrease in light use efficiency and a decrease in the amount of light at the end of the image plane, that is, a problem of so-called deterioration in shading performance.

[0007] Of these, a reduction in the light utilization can be solved by replacing the rated output of the laser oscillator with a large one, but an increase in the rating results in a significant increase in cost.

The present invention has been conceived in view of the above-mentioned facts, and has as its object to provide a low-cost soundproofing device which has a simple structure, does not effectively reduce light use efficiency, and is not affected by shading.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention comprises a plurality of shielding members having openings in a passage for a light beam or a fluid, the openings being large enough to allow the light beam or the fluid to pass through. It is characterized by being provided apart from each other.

[0010] Alternatively, a plurality of shielding members each having an opening large enough to allow the incident light beam and the outgoing light beam to pass therethrough are provided at the light incident portion and the light emitting portion of the optical deflector using the rotating polygon mirror. It is characterized by being provided separately.

Each of the openings of the shielding member is made to have a minimum size, and each opening is made different depending on the enlargement or reduction of the light beam. May be provided along the optical path, or one of the openings through which the incident light beam passes may also serve as a stop.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the configuration of one embodiment of the present invention.
A portion surrounded by rectangular surfaces A and A 'shown in FIG. In the middle of this passage 21, 3
A plurality of shielding members 22, 23 and 24 are placed, and openings 22a, 23a and 24a are formed in each shielding member. Each opening has substantially the same size as the light flux or fluid passage 21.

Consider a case where a light beam or a fluid travels in the passage 21 from A to A 'in the direction of arrow B. Shielding members 22, 2
Reference numerals 3 and 24 each have a thickness t and are arranged at intervals of S ₁ and S ₂ , respectively.

FIG. 2 is a view of the configuration of FIG. 1 viewed from the direction of arrow C. The noise reduction effect of the present invention will be described with reference to FIG.

If it is assumed that the sound source is present at the starting surface A of the passage 21, it is considered that sound waves are radially diffused from A. When the sound wave advances in the direction of arrow B, first, the sound wave that does not pass through the opening 22a of the first shielding member 22 is blocked, and a part of the sound wave passes through the opening 22a. The sound wave that passed
Due to the nature of the waves, as shown in FIG.
2 is substantially radially diffused from the opening 22a.
Although it reaches the second shielding member 23, it is part of the entire sound wave that has passed through the opening 22a of the first shielding member,
Naturally, sound waves are attenuated.

The same occurs in the openings 23a and 24a of the second and third shielding members 23 and 24, and the sound wave is attenuated each time it passes through one of the shielding members, and finally becomes very weak. Go outside. Such an effect works similarly in the direction of the cross section viewed from the direction perpendicular to the arrow C.

In the above embodiment, it is assumed that the sound source is located on the surface A. In this case, since the sound source is located on the front in the direction of arrow B, the sound finally leaking to the outside becomes the largest. However, in actuality, the sound source is located at a position offset from A-A ', and the traveling direction of the sound wave is non-uniform due to the influence of reflected waves and the like. growing.

Further, in the above example, three shielding members have been described, but it goes without saying that the greater the number, the more effective. Further, the plate thickness t and the intervals S ₁ , S ₂ do not need to be the same, and the shapes and areas of the openings 22 a, 23 a, 24 a do not need to be the same as long as the light flux and the fluid passage 21 can be secured.

FIG. 3 is a modification of FIG. In this embodiment, the shielding members 22 ', 23', 24 'are arranged in a zigzag manner on the lower side with respect to the upper shielding members 22, 23, 24. An opening 22a is provided between the shielding members 22 and 22 '.
The space between the shielding members 23 and 23 'corresponds to the opening 23a, and the space between the shielding members 24 and 24' corresponds to the opening 24a. Even with such a configuration, the attenuation of the noise is the same as the embodiment of FIGS. In addition, according to the embodiment shown in FIGS. 1 to 3, a dustproof effect due to the labyrinth shape can be expected.

FIG. 4 shows an embodiment in which the present invention is applied to a rotary polygon mirror used in an optical deflector. The rotating polygon mirror 4 is fixed in the optical housing 1 as described with reference to FIG. Incident light beam L ₀ is emitted from the laser light source (not shown), is reflected by the reflecting surface of the rotary polygon mirror 4 is scanned from L ₁ in the range of L _2, as described in FIG. 7, the photosensitive drum through the subsequent optical elements An original image is formed on the top. Shielding member 2
2, 23, 24 are formed integrally with the optical housing 1, and the upper surface thereof is flush with the upper surface of another soundproof wall 26 formed around the rotary polygon mirror 4. Therefore,
An optical housing cover (not shown) is in close contact with these upper surfaces, and the rotary polygon mirror 4 is sealed except for the openings 22a, 23a, and 24a of the shielding member.

Openings 22 of shielding members 22, 23, 24
It is desirable that the apertures a, 23a, and 24a have minimum apertures corresponding to the scanning range of the incident light beam L ₀ and the outgoing light beams L ₁ and L ₂ spreading in a fan shape. In other words, these openings are larger at positions farther from the rotary polygon mirror. As shown in FIG. 5, the longitudinal direction of the opening is the main scanning direction, and the direction orthogonal thereto is the sub-scanning direction. The length in the sub-scanning direction, that is, the width W of the opening is also determined from the rotating polygon mirror 4. It is enlarged as it goes away. Of course, this expansion is also necessary and minimal for the passage of the light beam.

FIG. 6 shows a modification of the embodiment shown in FIG. In this embodiment, a partition 28 is provided in the middle to separate an opening through which an incident light beam and an outgoing light beam pass. With such a configuration, each opening is
Since the incident light beam and the outgoing light beam are allowed to pass through, the minimum is required, and the size of the opening can be reduced, so that the noise reduction effect is increased. In addition, the labyrinth effect is also improved. Further, by setting one of the openings through which the incident light beam passes as the stop 29, a further effect can be obtained.

[0023]

As described above, according to the present invention, a plurality of shielding members each having an opening having a size through which the light beam or the fluid can pass are separated from each other in the passage for the light beam or the fluid. As a result, the noise is attenuated each time it passes through the opening of each shielding member, and the noise leaking to the outside can be reduced to a low level with a simple configuration and therefore at low cost. In addition, a dustproof effect due to the labyrinth effect of the shielding member can be expected.

A plurality of shielding members having openings large enough to allow the incident light beam and the outgoing light beam to pass therethrough are separated from each other at the light incident portion and the light emitting portion of the optical deflector using the rotating polygon mirror. With such a configuration, it is possible to obtain an optical polarizer with less noise from the rotating polygon mirror. Further, since there is no shield such as a sheet glass at the opening, there is no loss of light energy and no shading effect, there is no need to increase the output of the laser light source, and the effect of cost increase is small.

If each of the openings of the above-mentioned shielding member is made to have a minimum necessary size and is made different depending on the enlargement or reduction of the light beam, it is effective without affecting the image formation. .

If a partition for dividing the incident light beam and the outgoing light beam is provided along the optical path, the aperture can be further reduced, so that more effective noise reduction can be achieved. If any one of the openings through which the incident light beam passes also functions as a stop, the opening area can be further reduced, and the noise reduction effect is also improved.

[Brief description of the drawings]

FIG. 1 is a perspective view conceptually showing a basic configuration of a muffler of the present invention.

FIG. 2 is a sectional view as viewed from C in FIG. 1;

FIG. 3 is a diagram showing a state in which the shielding members are arranged in a staggered manner in FIG. 2;

FIG. 4 is a perspective view showing a state in which the noise reduction device of the present invention is applied to a rotating polygon mirror of an optical deflector.

FIG. 5 is a partial view of the shielding member and the opening as viewed from D in FIG. 4;

FIG. 6 is a perspective view of an embodiment in which a partition is provided between an incident light beam and an outgoing light beam in the embodiment of FIG.

FIG. 7 is a top view showing a configuration of a conventional optical deflector.

FIG. 8 is a sectional view showing a configuration of a portion of the rotary polygon mirror of FIG. 7;

[Explanation of symbols]

1 optical housing 4 rotary polygon mirror 21 passages 22, 23, 24, the shielding member 22a, 23a, 24a opening 28 the partition wall 29 aperture L ₀ incident light beam L _1, L ₂ emitted beam

Claims (5)

[Claims] 1. A muffler, wherein a plurality of shielding members having openings sized to allow passage of the light beam or the fluid are provided at a distance from each other in a passage for the light beam or the fluid. 2. A light deflector using a rotary polygon mirror, a plurality of shielding members having an opening large enough to allow the incident light beam and the outgoing light beam to pass through at a light entrance portion and a light exit portion. A silencer characterized by being spaced apart. 3. The shielding member according to claim 2, wherein each opening of the shielding member has a minimum size and is different for each shielding member in accordance with expansion or contraction of a light beam. Silencer. 4. The muffler according to claim 2, wherein a partition wall for dividing the incident light beam and the outgoing light beam is provided along an optical path. 5. The muffler according to claim 2, wherein one of the openings through which the incident light beam passes also functions as a stop.