JP2000238326A - Noise-preventing mechanism of image-forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce noises by preventing generation of resonance in a sealed space of an optical housing and a driving gear box, and reduce production costs of an apparatus by sharing the optical housing and driving gear box among different types. SOLUTION: A cover 22 of an optical housing 20 is moved thereby adjusting a size of a sealed space in the housing 20. An acoustic resonance frequency of the housing is adjusted accordingly. Even when a type of the apparatus is different and an oscillation frequency of a polygon mirror 5 changes, the acoustic resonance frequency of the housing can be adjusted not to agree with the oscillation frequency of the polygon mirror 5, so that generation of resonance in the housing 20 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to a technique for preventing noise from an image forming apparatus.

[0002]

2. Description of the Related Art Conventionally, an image forming apparatus for forming an image by transferring a toner image formed on an image carrier onto a recording medium and having a mechanism for preventing generation of noise from the image forming apparatus. For example, in standby mode, the noise generated due to the rotational vibration of the polygon mirror is reduced by lowering the rotation speed of the polygon mirror in the optical housing than during paper conveyance (exposure). . Further, there is a type in which a drive frame provided with a photoreceptor drive system is covered with a cover so as to block noise caused by surface vibration of the drive frame.

[0003]

However, in the noise prevention mechanism for reducing the rotation speed of the polygon mirror during standby as described above, the noise from the optical housing generated by the rotation vibration of the polygon mirror during paper conveyance can be reduced. Can not. Further, in the noise prevention mechanism that blocks noise generated from the photoconductor drive system by the cover that covers the drive frame as described above, the acoustic resonance frequency (frequency causing natural vibration) of the drive gear box including the cover and the like.
And the vibration frequency of the photoconductor drive system may coincide with each other to cause resonance. Even when the cover height is set so that these frequencies do not match, the system speed of the photoconductor drive system is changed to change the frequency of the gear meshing vibration, or the temperature environment in the drive gearbox may change. If the acoustic resonance frequency of the drive gear box changes, resonance may occur.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made in order to adjust the acoustic resonance frequency of an optical housing and a drive gear box in an image forming apparatus. Even if the vibration frequency of the vibration oscillation source changes or the temperature environment changes, noise can be reduced by preventing the occurrence of resonance inside the optical housing and drive gear box, and furthermore, between models. Accordingly, it is an object of the present invention to provide a noise prevention mechanism for an image forming apparatus capable of reducing the manufacturing cost by using a common optical housing and a drive gear box.

[0005]

According to a first aspect of the present invention, there is provided an optical housing comprising a closed space containing an optical system for forming an image, wherein the optical housing includes a vibration source. In the noise prevention mechanism of the image forming apparatus including the source, the size of the closed space in the optical housing is adjustable.

In the above configuration, the acoustic resonance frequency of the optical housing can be adjusted by adjusting the size of the closed space in the optical housing. Therefore, even if the model is different and the vibration frequency of the vibration oscillation source in the optical housing changes, it is possible to adjust the acoustic resonance frequency of the optical housing so that it does not match the vibration frequency of the vibration oscillation source. Can be prevented from occurring.

Further, the optical housing may include a housing main body and a cover for the housing main body, and the cover may be configured to be slidable with respect to the housing main body. Thus, the size of the closed space in the optical housing can be easily adjusted only by sliding the cover, and the acoustic resonance frequency of the optical housing does not match the vibration frequency of the vibration oscillation source. .

Further, a member having a vibration isolating property may be used at the joint between the housing body and the cover. Thereby, the internal space of the optical housing can be made dense, and the vibration isolation of the optical housing can be increased.

Further, the cover may be provided with vibration damping properties.
Thereby, the vibration isolation of the optical housing can be increased.

[0010] Further, at least one of the walls constituting the closed space in the optical housing may automatically move in accordance with the temperature in the optical housing. Accordingly, even when the speed of sound in the optical housing changes due to a change in the temperature environment of the optical housing, the acoustic resonance frequency in the optical housing can be kept constant, so that occurrence of resonance can be prevented.

Further, the vibration source is a polygon mirror,
The wall may be moved to a position where the acoustic natural frequency of the closed space in the optical housing does not coincide with one rotation frequency of the polygon mirror or this frequency multiplied by the number of mirror surfaces of the polygon mirror. Thus, it is possible to prevent occurrence of resonance between the incident wave of sound from the polygon mirror to the wall and the reflected wave from the wall with respect to the incident wave.

The wall may be moved by using a bimetal. Accordingly, the sound speed changes with the change of the temperature environment of the optical housing, and even if the wavelength of the sound generated in one rotation cycle of the polygon mirror or a cycle obtained by dividing this cycle by the number of mirror surfaces of the polygon mirror changes. Thus, it is possible to prevent occurrence of resonance between an incident wave of sound from the polygon mirror to the wall and a reflected wave from the wall with respect to the incident wave.

The wall may be made of a shape memory alloy. Thereby, an operation equivalent to the above can be obtained.

According to a ninth aspect of the present invention, there is provided a noise prevention mechanism for an image forming apparatus, comprising a drive frame for supporting a drive system for driving an image carrier for image formation, separately from a main body frame of the apparatus. In the above, the drive frame is provided with a sound insulation cover that covers the frame, the sound insulation cover forms a closed space including the drive frame inside, and at least one surface of the sound insulation cover is configured to be movable. In this configuration, the noise from the drive system of the image carrier can be cut off by using the sound insulating cover, and the size of the closed space formed by the inside of the sound insulating cover is changed by moving the sound insulating cover. Thus, the acoustic resonance frequency in the closed space can be adjusted. Therefore, even when the temperature environment inside the sound insulation cover changes and the sound speed and the acoustic resonance frequency inside the sound insulation cover change, the acoustic resonance frequency is not matched with the frequency of the vibration generated from the drive sequence of the image carrier. Therefore, occurrence of resonance in the sound insulation cover can be prevented.

The joint between the sound insulation cover and the main body frame may have a vibration isolation property. Thereby, the internal space of the sound insulation cover can be made dense, and the sound insulation can be increased.

Further, the sound insulating cover may have a vibration damping property. Thereby, the vibration isolation of the sound insulating cover can be increased.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a noise prevention mechanism of an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an image forming apparatus to which a noise prevention mechanism is applied. This apparatus is an electrophotographic printer that forms an image based on image information input from an externally connected device such as an image reader or a personal computer. The printer 1 includes a print head 2 (hereinafter, referred to as P / H) for irradiating a laser beam and a photosensitive drum 3. P / H2 has a laser diode (LD) 4, a polygon mirror 5,
It has a laser optical system including a folding mirror 6 and the like, and irradiates a laser beam. Below P / H2, P
A P / H base plate 7 for supporting / H2 is provided. P /
The laser beam emitted from H2 passes through a slit 7a provided in the P / H base plate 7, and exposes the photosensitive drum 3 charged by the charger 9 to form an electrostatic latent image on the photosensitive drum 3. Form an image. This electrostatic latent image is developed with toner by a developing device 10 provided around the photoconductor 3. The recording paper P is taken out of the paper supply cassette 11 by a paper supply roller 12 and transported by a transport roller 13 to a position of a transfer roller 14. The toner image developed on the photosensitive drum 3 is transferred onto the recording paper P sandwiched between the photosensitive drum 3 and the transfer roller 14. Thereafter, the recording paper P is conveyed to a fixing roller 15 including a pair of heat rollers and a pressure roller, and the transfer roller image on the recording paper P is heated and pressed by the fixing roller 15 to be fixed. . The recording paper P after the fixing is discharged to the paper discharge tray 16.

The structure of the P / H2 according to the first embodiment will be described with reference to FIG. The P / H 2 is protected by an optical housing 20 including an optical housing main body 21 and a housing cover 22, and is devised so that resonance does not occur in an internal closed space. The optical housing 20 can be adjusted in height by sliding the housing cover 22 up and down at the time of assembling so as to be shared with other types of printers. The polygon mirror 5 inside the P / H 2 emits regular rotational vibration at a constant frequency during exposure. When the frequency of the rotational vibration of the polygon mirror 5 matches the acoustic resonance frequency (frequency at which natural vibration occurs) of the optical housing 20, resonance occurs in the optical housing 20. Since the inside of the optical housing 20 forms a closed space, the acoustic resonance frequency of the optical housing 20 is determined by the size and the speed of sound of the optical housing 20. In addition, polygon mirror 5
Is installed on the bottom plate of the optical housing 20, the rotational vibration from the polygon mirror 5 is mainly transmitted from bottom to top, so that the acoustic resonance frequency of the optical housing 20 is actually higher than the height of the optical housing 20. And sound speed. Accordingly, the acoustic resonance frequency of the optical housing 20 can be adjusted by changing the height of the optical housing 20 by sliding the housing cover 22 in the direction indicated by the arrow. Thus, even when the type of the printer changes and the rotational vibration frequency of the polygon mirror 5 changes, the acoustic resonance frequency of the optical housing 20 is adjusted, and this acoustic resonance frequency is shifted from the rotational vibration frequency of the polygon mirror 5. Optical housing 2
The occurrence of resonance in zero can be prevented.

The sliding mechanism of the housing cover 22 will be described with reference to FIGS. FIG. 3 (a)
As shown in FIG. 2, a hole 22a is provided in a side wall of the housing cover 22, and a plurality of holes 21a are provided in a side surface of the optical housing body 21. At the time of assembling the apparatus, the housing cover 22 is fixed to the optical housing main body 21 by screwing the screws 23 into these holes 21a and 22a. At this time, the holes 21a into which the screws 23 are screwed are inserted.
, The housing cover 22 can be slid up and down. Further, as shown in FIG. 3B, the hole in the side wall of the housing cover 22 is
As 1b, the housing cover 22 may be slid by moving the position where the screw 23 in the long hole 21b is screwed up and down. It is desirable to use an elastic member for the joint between the optical housing body 21 and the housing cover 22. For example, by providing an elastic member made of rubber on the inner surface of the housing body 21 or the outer surface of the housing cover 22, the space inside the optical housing 20 can be made denser and the sound insulation can be increased. The housing cover 22 is preferably made of a damping material such as a damping steel plate or a damping alloy, so that noise caused by the rotational vibration of the polygon mirror 5 is hardly leaked to the outside. Can be.

Next, an example in which a noise prevention mechanism is applied to a drive gear box having a drive system for the photosensitive member 3 will be described with reference to FIG. The drive gear box 30 is devised to prevent the occurrence of resonance similarly to the optical housing 20, and includes a main body frame 31 of the apparatus, a sound insulation cover main body part 38 provided integrally with the main body frame 31, and a sound insulation cover. The slide portion 37 is formed. By sliding the sound-insulating cover slide portion 37 in the direction of the arrow shown in the figure, the size in the left-right direction can be adjusted. A drive frame 33 is provided inside the drive gear box 30.
The drive frame 33 is provided with a motor 32.
And a gear 34 for transmitting the driving force to the photoconductor 3,
35 is provided. The rotation of the shaft 32 a of the motor 32 is transmitted to the shaft 36 of the photoconductor 3 via gears 34 and 35.
At this time, meshing vibration B is generated between the gear 34 and the gear 35. Further, a surface vibration A mainly caused by the meshing vibration B is generated in the drive frame 33 which supports the gear 34 and the gear 35. The frequency of the surface vibration A is the same as the frequency of the meshing vibration B. The frequency of these vibrations A and B,
When the acoustic resonance frequencies of the drive gear box 30 match,
Resonance occurs in the drive gear box 30. The acoustic resonance frequency of the drive gear box 30 is
In the vibration transmission direction (the size in the left-right direction in FIG. 4) and the speed of sound. Therefore, the sound insulation cover slide part 3
7 is slid in the direction of the arrow shown in the figure to adjust the acoustic resonance frequency of the drive gear box 30 so that the acoustic resonance frequency is shifted from the plane vibration A and the meshing vibration B, and the occurrence of resonance in the drive gear box 30 is reduced. Can be prevented. Thus, noise radiated from the drive gear box 30 to the outside can be reduced.

Even if the temperature environment around the entire apparatus or the drive gear box 30 changes, the sound speed inside the drive gear box 30 changes, and the acoustic resonance frequency of the drive gear box 30 changes, the sound insulation cover slide portion 37 slides. By doing so, the acoustic resonance frequency of the drive gear box 30 can be adjusted to prevent the occurrence of resonance. Also,
Even when the type of the printer changes and the frequency of the gear meshing vibration of the photoconductor driving system changes, the acoustic resonance frequency of the driving gear box 30 is adjusted by sliding the sound-insulating cover slide 37 to reduce the occurrence of resonance. Can be prevented. As a result, the entire drive gear box 30 or the sound-insulating cover slide portion 3 can be communicated with another type of printer.
7 can be shared.

When the surface vibration A or the meshing vibration B is incident on the sound-insulating cover slide 37, the sound-insulating cover slide 37 reflects the reflected wave C having the same frequency as the vibrations A and B.
Is reflected, and the surface vibration A or the meshing vibration B and the reflected wave C
Resonance may occur. This resonance causes the sound insulation cover slide portion 37 to move from the drive frame 33, which is the surface where the surface vibration A is generated.
Or the distance from the gear mesh point, which is the source of the meshing vibration B, to the sound insulation cover slide portion 37,
Occurs when the wavelength of the vibrations A and B is an integral multiple of half the wavelength. The sound insulation cover slide 37 is slid in the direction of the arrow shown in the figure to change the distance from the source of the surface vibration A or the meshing vibration B to the sound insulation cover slide 37, so that the surface vibration A or the meshing vibration B is reflected by the reflected wave. The resonance with C can be prevented, and the noise radiated from the drive gear box 30 to the outside can be further reduced.

FIGS. 5A and 5B show the slide mechanism of the sound-insulating cover slide portion 37. FIG. This configuration corresponds to FIG.
(A) It is the same as the slide mechanism of the housing cover 22 shown in (b). A hole 37a is provided in a side wall of the sound insulating cover slide portion 37, and a plurality of holes 31a or a long hole 31b is provided in a sound insulating cover body portion 38 which is a side wall of the main body frame 31, and a hole 31a into which a screw 39 is screwed is provided. The sound insulation cover slide 37 can be slid by changing the position or moving the screw 39 in the elongated hole 31b up and down. It is desirable to use an elastic member for the joint between the sound insulation cover main body 38 and the sound insulation cover slide 37 in the same manner as described above, so that the space inside the drive gear box 30 is made denser and the sound insulation of the drive gear box 30 is reduced. Sex can be increased. The sound insulation cover slide portion 37 is desirably made of a material having the same vibration damping properties as described above, so that the surface vibration A and the meshing vibration B can be hardly leaked to the outside.

Next, a second embodiment in which a noise prevention mechanism is applied to an optical housing will be described with reference to FIG. In the optical housing 20, the polygon mirror 5 and its driving system are provided in the same manner as in FIG.
A ceiling 41 supported by a bimetal support member 42 is provided. The support member 42 has two different thermal expansion coefficients.
Kinds of metal plates are bonded by a rolling method so that they are curved when the temperature changes. According to this configuration,
The height of the ceiling 41 is automatically adjusted according to the temperature environment, and the acoustic resonance frequency of the optical housing 20 is always kept constant irrespective of the temperature environment, thereby preventing the occurrence of resonance.

The speed of sound v in the air is represented by the following equation (1), where the temperature is t (° C.).

## EQU1 ## v = 331.5 + 0.5t (1)

Further, the sound velocity v, and the wavelength of the acoustic resonance and lambda _1, the acoustic resonance frequency f ₁ is represented by the equation (2).

F ₁ = v / λ ₁ (2)

From the above equation (1), it can be seen that when the temperature inside the optical housing 20 increases, the sound speed v inside the optical housing 20 increases. From the above equation (2),
It can be seen that as the sound speed v increases, the acoustic resonance frequency f ₁ increases. Therefore, when the temperature inside the optical housing 20 is increased, the higher the acoustic resonance frequency f _1. On the other hand, the rotational vibration frequency of the polygon mirror 5 generated by driving the motor 5b is constant as long as the rotational speed of the motor 5b does not change. Therefore, depending on the temperature inside the optical housing 20, and an acoustic resonance frequency f ₁ of the optical housing 20 is changed to the same frequency as the rotational vibration frequency of the polygon mirror 5, there is a possibility that resonance may occur. In order to prevent the occurrence of the resonance, the optical housing 20 is set so that the acoustic resonance frequency f ₁ of the optical housing 20 does not coincide with the rotational vibration frequency of the polygon mirror 5 during assembly of the apparatus.
The height of the ceiling 41 of the optical housing 20 is adjusted.
The acoustic resonance frequency f ₁ may be set to a constant value irrespective of a temperature change similarly to the rotational vibration frequency of the polygon mirror 5. To this end, as can be seen from the above equation (2), the value of the wavelength λ ₁ of the acoustic resonance may be increased in accordance with the value of the sound velocity v that increases as the temperature rises.
Since the wavelength of the natural vibration of the optical housing 20, that is, the wavelength λ _{1 of the} acoustic resonance is proportional to the height of the optical housing 20, the ceiling 41 is moved in response to the temperature rise by using the property of the bimetallic support member 42. By increasing the sound speed v
, The value of the wavelength λ ₁ of the acoustic resonance can be increased. Thus, regardless of the optical housing 20 internal temperature, since the rotational vibration frequency of the acoustic resonance frequency f ₁ and the polygon mirror 5 can be prevented match, it is possible to prevent the occurrence of resonance.

Also, with the rotation of the polygon mirror 5,
The sound is generated in one rotation cycle of the polygon mirror 5 or in a cycle obtained by dividing this cycle by the number of mirror surfaces of the polygon mirror 5.
When this sound wave enters the ceiling 41 of the optical housing 20, a reflected wave of the sound wave is generated from the ceiling 41, and when the sound wave and the reflected wave resonate, the sound generated from the polygon mirror 5 increases. This resonance is caused by the polygon mirror 5
This occurs when the distance from the ceiling to the ceiling 41 is an integral multiple of half the wavelength λ ₂ of the sound emitted from the polygon mirror 5. Therefore, it is necessary to adjust the distance from the polygon mirror 5 to the ceiling 41 by moving the ceiling 41 up and down so that resonance does not occur.

The details will be described below. The wavelength λ ₂ of the sound emitted from the polygon mirror 5 is represented by f
₂ , if the sound speed is v, it is expressed by equation (3).

Λ ₂ = v / f ₂ (3)

As described above, the value of the sound velocity v increases as the temperature t inside the optical housing 20 increases. On the other hand, the frequency f ₂ of the sound wave emitted from the polygon mirror 5 is
As long as the rotation speed of the polygon mirror 5 does not change, it is constant. Therefore, from the above equation (3), the optical housing 20
When the value of the sound speed v increases with an increase in the internal temperature t, the sound wavelength λ ₂ increases. Therefore, the temperature t
Depending on the value of the distance, the distance from the polygon mirror 5 to the ceiling 41 is equal to the wavelength λ ₂ of the sound emitted from the polygon mirror 5.
There is a possibility that resonance between the sound wave and the reflected wave may occur.

Therefore, in order to prevent the occurrence of resonance, the distance from the polygon mirror 5 to the ceiling 41 is changed according to the length of the sound wavelength λ ₂ , and the distance from the polygon mirror 5 is changed regardless of the value of the temperature t. It is necessary to ensure that the distance to the ceiling 41 does not always become an integral multiple of half the wavelength λ ₂ . Here, in the present embodiment, the supporting member 4 made of bimetal is used.
Since the ceiling 41 is supported by 2, it acts to raise the ceiling 41 in accordance with the rise in the temperature t. Therefore, the distance from the polygon mirror 5 to the ceiling 41 is always constant regardless of the value of the temperature t. The wavelength can be prevented from being an integral multiple of half the wavelength λ ₂ . As a result, it is possible to prevent resonance between the sound wave emitted from the polygon mirror 5 and the reflected wave.

Next, a third embodiment of the optical housing will be described with reference to FIG. In this embodiment, two hoods 44 made of a shape memory alloy, one end of which is pivotally supported by a shaft 45 and the other end of which is open, are disposed in the optical housing 20 so as to surround the polygon mirror 5. . In order to return to the original shape when the temperature t rises, the shape memory alloy hood 44 is displaced in a direction away from the polygon mirror 5 as indicated by an arrow in response to the rise in the temperature t. Thus, resonance between the sound wave diffused in the horizontal direction from the polygon mirror 5 and the reflected wave is prevented. As described above, the wavelength λ _{2 of} the sound generated from the polygon mirror 5
Becomes longer as the temperature t rises. Therefore, in order to prevent the occurrence of resonance between the sound wave and the reflected wave, the polygon mirror 5 is moved according to the value of the temperature t, that is, in accordance with the wavelength λ ₂ of the longer sound. It is necessary to adjust the distance to the sound incident surface, that is, the inner surface of the hood 44. Here, the shape memory alloy hood 44 is displaced as described above according to the rise in the temperature t, and the distance from the polygon mirror 5 to the sound incident surface can be increased. The resonance between the sound wave diffused to the surface and the reflected wave can be prevented.

The present invention is not limited to the above embodiment, but can be variously modified. For example, the size of the internal space of an imaging cartridge including a photosensitive member can be adjusted according to the temperature environment. You may.

[0034]

As described above, according to the first aspect of the present invention,
Since the size of the closed space in the optical housing can be adjusted, the acoustic resonance frequency of the optical housing can be adjusted. Therefore, even when the vibration frequency of the vibration oscillation source changes due to a change in the device model, the optical By preventing the occurrence of resonance inside the housing, noise generated from the optical housing and the drive gear box can be reduced. As a result, the optical housing can be shared between the respective models, and the cost of manufacturing the device can be reduced.

Also, by making the cover of the optical housing slidable with respect to the housing body,
The size of the closed space in the optical housing can be easily adjusted.

In addition, by using a member having a vibration isolating property at the joint between the housing body and the cover, the internal space of the optical housing can be made denser, and the vibration isolating property of the optical housing can be increased.

Further, by using a material having a vibration damping property for the cover, the vibration shielding property of the optical housing can be increased.

Further, by automatically moving a wall constituting a closed space in the optical housing according to the temperature in the optical housing, the acoustic resonance frequency in the optical housing is changed in accordance with a change in the temperature environment of the optical housing. Even if the value changes, the occurrence of resonance can be prevented, and the noise generated from the optical housing can be reduced.

Further, by moving the wall to a position where the acoustic natural frequency of the closed space in the optical housing does not coincide with one rotation frequency of the polygon mirror or a frequency obtained by multiplying this frequency by the number of mirror surfaces of the polygon mirror, Resonance between the incident wave of vibration from the polygon mirror to the wall and the reflected wave can be prevented, and noise generated from the optical housing can be reduced.

Further, by moving the wall using a bimetal, even if the temperature environment of the optical housing changes, the occurrence of resonance can be automatically prevented.

Further, by forming the above-mentioned wall with a shape memory alloy, the same effect as above can be obtained.

According to the ninth aspect of the present invention, since the sound insulating cover which covers the drive frame and forms a closed space including the image carrier driving system therein is made movable, the image carrier driving with the sound insulating cover is possible. The noise from the series can be cut off, and the size of the closed space can be changed to adjust its acoustic resonance frequency. Therefore, even if the temperature environment in the closed space changes, the closed space can be closed. Can prevent the occurrence of resonance. In addition, even if the model of the apparatus changes and the gear meshing frequency, which is the source of vibration of the image carrier drive system, changes, the occurrence of resonance can be prevented. In addition, the cost for manufacturing the device can be reduced.

Further, by providing the joint between the sound insulating cover and the main body frame with vibration isolation, noise generated from inside the sound insulating cover can be reduced.

Further, by providing the sound insulating cover with vibration damping properties, the sound insulating properties of the sound insulating cover can be increased.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an example of a printer to which a noise prevention mechanism according to the present invention is applied.

FIG. 2 is a schematic sectional view of an optical housing in the printer according to a first embodiment;

FIGS. 3A and 3B are cross-sectional views illustrating an example of a slide mechanism of a cover in the optical housing.

FIG. 4 is a sectional view showing an embodiment in which the noise prevention mechanism of the present invention is applied to a drive gear box.

FIGS. 5A and 5B are cross-sectional views illustrating an example of a slide mechanism of a sound-insulating cover slide portion in the drive gear box.

FIG. 6 is a schematic sectional view of an optical housing according to a second embodiment;

FIG. 7 is a schematic cross-sectional view of an optical housing according to a third embodiment;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printer (image forming apparatus) 5 Polygon mirror (vibration source) 20 Optical housing 21 Optical housing main body (housing main body) 22 Housing cover 33 Drive frame (vibration generation source) 37 Sound insulation cover slide part 41 Ceiling (wall) 42 Support member 44 Hood made of shape memory alloy

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03G 21/00 530 G03G 21/00 530 F-term (Reference) 2C061 AQ06 2C362 BA04 BA90 CB59 DA17 DA20 2H027 JA17 JC05 2H045 AA33 DA02 DA41 2H071 BA22 DA02 EA14

Claims (11)

[Claims] 1. A noise prevention mechanism for an image forming apparatus, comprising: an optical housing forming a closed space containing an optical system for forming an image, wherein the optical housing includes a vibration source. A noise prevention mechanism for an image forming apparatus, wherein a size of a closed space in a housing is adjustable. 2. The image forming apparatus according to claim 1, wherein the optical housing includes a housing main body and a cover for the housing main body, and the cover is configured to be slidable with respect to the housing main body. Equipment noise prevention mechanism. 3. A noise prevention mechanism for an image forming apparatus according to claim 2, wherein a member having a vibration isolation property is used for a joint between said housing body and said cover. 4. The noise prevention mechanism for an image forming apparatus according to claim 2, wherein said cover has vibration damping properties. 5. The image according to claim 1, wherein at least one of walls forming a closed space in the optical housing automatically moves according to a temperature in the optical housing. Noise prevention mechanism of forming equipment. 6. The vibration source is a polygon mirror, and the wall is configured such that the acoustic natural frequency of the closed space in the optical housing is equal to one rotation frequency of the polygon mirror, or the number of mirror surfaces of the polygon mirror is determined by this frequency. The noise prevention mechanism for an image forming apparatus according to claim 5, wherein the mechanism moves to a position that does not match the multiplied frequency. 7. The noise prevention mechanism for an image forming apparatus according to claim 5, wherein the wall is moved by using a bimetal. 8. The noise prevention mechanism for an image forming apparatus according to claim 5, wherein said wall is made of a shape memory alloy. 9. A noise prevention mechanism for an image forming apparatus, comprising: a drive frame for supporting a drive system for driving an image carrier for image formation, separately from a main body frame of the apparatus. A sound-insulating cover that covers the frame is provided, the sound-insulating cover forms a closed space including the drive frame therein, and at least one surface of the sound-insulating cover is configured to be movable. Noise prevention mechanism for image forming apparatus. 10. The vibration-shielding property of the joint between the sound-insulating cover and the main body frame.
2. The noise prevention mechanism for an image forming apparatus according to claim 1. 11. The noise prevention mechanism for an image forming apparatus according to claim 9, wherein said sound insulation cover has a vibration damping property.