JP2002244380A - Image carrier driving unit and image forming apparatus using the same - Google Patents

Abstract

(57) [Summary] An image carrier driving unit capable of reducing noise is provided.
And an image forming apparatus using the same. SOLUTION: Drive from a drive motor 53 is performed by a gear train 51.
Is transmitted to the photoreceptor 17 through the
In the photoreceptor drive unit 50, which rotates,
Is provided, and the resonator 57 is provided with a predetermined
A hollow member 59 having a space 60;
A short pipe 61 communicating the internal space 60 with the outside.
The volume of the internal space 60 of the hollow member 59, the length of the short pipe 61,
And at least one of the cross-sectional areas of the short pipe 61 can be changed
And the resonance frequency f of the resonator 57 _HIs the drive motor 5
3 rotation frequency f_mMatches or approximates

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image carrier driving unit and an image forming apparatus using the same, such as an electrophotographic copying machine, a facsimile, and a printer.

[0002]

2. Description of the Related Art Conventionally, passive measures using sound absorbing and sound insulating materials have been mainly used for noise prevention, but active noise control (Ac)
Although the concept of "active noise control" intentionally emits a sound in the opposite phase and cancels the interference by interference, it has not been realized since practical applications require advanced control technology. In recent years, it has finally become possible to realize this with the development of signal processing technology. Famous such active noise controls are those applied to refrigerators and automobiles, etc., which cancel out the sound by interfering with the noise by producing opposite-phase sound using speakers or the like. It is.

Japanese Patent Application Laid-Open No. 4-469, which discloses the use of Helmholtz, reduces the meshing noise generated in a gear unit provided adjacent to a developing unit of an image forming apparatus such as a laser printer. For this reason, the noise of the developing unit is reduced by providing a soundproof cover that covers a gear unit provided adjacent to the developing unit and connecting a hollow silencer to the soundproof cover.

[0004]

A rotary drive system such as a photoconductor drive unit of the image forming apparatus is indispensable in the image forming apparatus. Such a photoconductor drive unit generates noise due to rotation of a motor and meshing of gears. However, the technology disclosed in the publication cannot reduce such noise, and the noise in such a photoconductor drive unit cannot be reduced. It is desired to reduce this.

Accordingly, an object of the present invention is to provide an image carrier driving unit capable of reducing noise and an image forming apparatus using the same.

[0006]

According to a first aspect of the present invention, there is provided an image carrier driving device in which a drive from a drive motor is transmitted to an image carrier via a drive transmitting means, whereby the image carrier is rotationally driven. The unit includes a resonator for reducing noise, the resonator including a hollow member having a predetermined internal space,
A short pipe communicating between the internal space of the hollow member and the outside, wherein at least one of the volume of the internal space of the hollow member, the length of the short pipe, and the cross-sectional area of the short pipe is changeable; the volume of the internal space is V, and the length of the short tube and L _H, the sectional area of the short pipe and S _H, when the speed of sound is c, the resonance of the resonator is determined by the following equation (1) frequency _{f H} is,
Wherein the matching or approximate to the rotational frequency f _m of the drive motor.

[0007]

(Equation 5)

According to the first aspect of the present invention, a resonator having a short tube and a hollow member is provided, and at least one of the volume of the internal space of the hollow member, the length of the short tube, and the sectional area of the short tube is provided. Since the frequency can be reduced, the frequency that can be reduced can be changed, so that the resonator becomes a Helmholtz resonator (Helmholtz vibration absorber) corresponding to various noise frequency bands, leading to low noise.

Further, the frequency f _H of the noise is most reduced by the Helmholtz resonator, by identical or close with the rotation frequency f _m of the drive motor, the motor rotation of remarkable noise generated in the image bearing member driving unit The sound can be effectively reduced, and a low-noise photoconductor drive unit can be obtained.

According to the second aspect of the present invention, the drive from the drive motor is transmitted to the image carrier through the drive transmission means, so that the image carrier drive unit in which the image carrier is rotationally driven reduces noise. The resonator includes a hollow member having a predetermined internal space, and a short pipe communicating the internal space of the hollow member with the outside. The volume of the internal space of the hollow member, the length of the short pipe are provided. And at least one of the cross-sectional areas of the short pipe can be changed, the volume of the internal space of the hollow member is V, the length of the short pipe is L _H, and the cross-sectional area of the short pipe is S
_{Let H} be the sound velocity, and the resonance frequency f _H of the resonator determined by the following equation (1) be the product of the number of gear rotations per unit time and the number of gear teeth of the drive transmission means. wherein the matching or approximate to the frequency f _G meshing are determined.

[0011]

(Equation 6)

According to the second aspect of the present invention, a resonator having a short tube and a hollow member is provided, and at least one of the volume of the internal space of the hollow member, the length of the short tube, and the sectional area of the short tube is provided. Because the frequency can be changed, the frequency that can be reduced can be changed, so that the resonator becomes a Helmholtz resonator corresponding to various noise frequency bands, leading to low noise.

Further, the frequency f _H of the noise is most reduced by the Helmholtz resonator, the rotational frequency of the drive motor (rotational speed of the units of the gear time Atari) f _m and the number of teeth z in the gear of the drive transmission means by matching or approximating the meshing frequency f _{G =} f m · _z gear calculated by the product, it is possible to effectively reduce the meshing sound of the striking noise of gears generated in the image bearing member driving unit A low-noise photoconductor drive unit can be obtained.

According to the third aspect of the present invention, the drive from the drive motor is transmitted to the image carrier via the drive transmitting means, so that the noise is reduced in the image carrier drive unit in which the image carrier is rotationally driven. The resonator includes a hollow member having a predetermined internal space, and a short pipe communicating the internal space of the hollow member with the outside. The volume of the internal space of the hollow member, the length of the short pipe are provided. And at least one of the cross-sectional areas of the short pipe can be changed, the volume of the internal space of the hollow member is V, the length of the short pipe is L _H, and the cross-sectional area of the short pipe is S
_H, and when the sound speed is c, the resonance frequency f _H of the resonator determined by the following equation (1) matches or approximates the string vibration frequency f _b of the timing belt of the drive transmission means. I do.

[0015]

(Equation 7)

According to the third aspect of the present invention, a resonator having a short tube and a hollow member is provided, and at least one of the volume of the internal space of the hollow member, the length of the short tube, and the sectional area of the short tube is provided. Because the frequency can be changed, the frequency that can be reduced can be changed, so that the resonator becomes a Helmholtz resonator corresponding to various noise frequency bands, leading to low noise.

The frequency f _H at which the noise is reduced most by the Helmholtz resonator coincides with or approximates the string vibration frequency f _b , thereby providing one of the remarkable noises generated in the image carrier driving unit. Therefore, the string vibration sound of the timing belt can be effectively reduced, and a low-noise photoconductor drive unit can be obtained.

According to a fourth aspect of the present invention, a drive motor is provided.
The drive of the motor to the image carrier via the drive transmission means
Image carrier driving unit that drives the image carrier to rotate
A resonator for reducing noise and an image carrier driving unit.
Frequency f of noise_kDetecting frequency detection
Means and a resonator based on a detection signal from the frequency detection means.
Control means for controlling the resonance frequency, wherein the resonator
A hollow member having a constant internal space, and the inside of the hollow member
A short pipe communicating between the space and the outside;
Small space volume, short tube length, and short tube cross-sectional area
At least one can be changed and the body of the internal space of the hollow member
The product is V and the length of the short tube is L_HAnd the cross-sectional area of the short pipe is S
_HAnd when the sound speed is c, the control means calculates the following equation:
The resonance frequency f of the resonator determined in (1)_HThe frequency
Frequency f detected by the detecting means _kTo match
The volume V of the internal space of the cavity member in the resonator,
Length L_H, And the cross-sectional area S of the short pipe_HAt least one of
One of them is changed.

[0019]

(Equation 8)

According to the fourth aspect of the present invention, a resonator having a short tube and a hollow member is provided, and at least one of the volume of the internal space of the hollow member, the length of the short tube, and the sectional area of the short tube is provided. Because the frequency can be changed, the frequency that can be reduced can be changed, so that the resonator becomes a Helmholtz resonator corresponding to various noise frequency bands, leading to low noise.

Further, the control means sets the frequency f _{H at} which noise is reduced most by the Helmholtz resonator to the internal space of the cavity member in the resonator so as to match the frequency f _k of the noise detected by the frequency detection means. By changing at least one of the volume V, the length of the short pipe LH, and the cross-sectional area SH of the short pipe,
It is possible to realize a resonator that can cope with a difference in speed depending on a printing mode, a speed change due to an environmental change, and the like, and thus can reduce noise actively.

The invention according to claim 5 is the invention according to claims 1 to 4
And an image carrier driving unit.

According to the fifth aspect of the present invention, the first aspect is provided.
By providing the image carrier unit according to any one of (1) to (4), a low-noise image forming apparatus can be obtained.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment will be described in detail with reference to the accompanying drawings. FIG. 1 is a configuration diagram schematically showing a copying machine to which the present invention is applied. The copying machine (image forming apparatus) 1 includes, in order from the top of the copying machine 1, a reading unit 3 for reading a document image, an image forming unit 5 for forming an image, and a paper feeding unit for feeding paper P. 7 are provided.

The reading section 3 is provided on a top surface of a cover 9 covering the periphery, a contact glass 11 for setting an original image (copy original) face down, and a reading glass 3 which can be opened and closed with respect to the contact glass 11. An original holder 13 for holding the copy original set thereon and an optical device 15 for reading the copy original set on the contact glass 11 and forming an electrostatic latent image on the photoreceptor 17 are provided.

The image forming section 5 has a photoconductor drive unit 50 (see FIG. 2) including a photoconductor (image carrier) 17.
Around the photoreceptor 17, a charging roller 19 that contacts the photoreceptor 17 and uniformly charges the surface of the photoreceptor 17 in the direction of rotation, and a developing sleeve 21 transfers the electrostatic latent image on the photoreceptor 17 to toner. Developing device 23 for visualizing as an image and photoconductor 1
A transfer device 25 for transferring the toner image of No. 7 onto paper P as a transfer material, and a cleaning device 29 for cleaning the photoconductor 17 by scraping off the toner remaining on the photoconductor 17 after the transfer with a cleaning blade 27 are arranged. I have.
Further, it is located at the lower left of the cleaning device 29 in FIG.
A fixing device 32 having a fixing roller 30 for applying heat and a pressure roller 31 for pressing the sheet P toward the fixing roller 30 and thermally fixing the toner image transferred to the sheet P is provided.

The paper feeding section 7 is located at the lower part of the copying machine 1, and is located at one end (right side in FIG. 1) of the paper feeding cassette 33 in which the paper P is stored. Paper feed roller 35 that is arranged and feeds paper P in paper feed cassette 33
And the paper P fed by the paper feed roller 35
And a sheet transport device 37 that transports the paper between the transfer device 7 and the transfer device 25.

The paper transporting device 37 is provided with the paper feed roller 3.
5, a plurality of guide plates 39 form a paper transport path 40 that is folded in a substantially U shape from the right side in the drawing toward the space between the photoreceptor 17 and the transfer device 25.
An intermediate roller pair 41a, a second intermediate roller pair 41b, and a registration roller pair 43 are arranged. First and second
An intermediate clutch (not shown) is disposed on each of the intermediate roller pairs 41a and 41b, and a registration clutch (not shown) is disposed on the registration roller pair 43.
Intermediate roller pair 41a, 41b, registration roller pair 43
Are rotated intermittently by a driving force from a motor (not shown) of the copying machine 1 via an intermediate clutch and a registration clutch.

When an image is formed using the copying machine 1, first, the document holder 13 is opened and the contact glass 11 is opened.
The copy original is set face down, the original holder 13 is closed, and the copy original is pressed from above. Thereafter, a start switch provided on an operation panel (not shown) of the copying machine 1 is pressed. When the start switch is depressed, the optical device 15 is operated, and optical scanning is performed along the contact glass 11 to read the original content of the copy original on the contact glass 11.

At the same time, the paper feed roller 35 and the first and second intermediate rollers 41a and 41b are rotated by transmitting the rotational drive of the motor 51 of the drive mechanism 47 by turning on the paper feed clutch and the intermediate clutch. . The paper P in the paper feed cassette 33 is fed out by the rotation of the paper feed roller 35. The fed sheet P is conveyed by the first and second intermediate rollers 41a and 41b through the sheet conveyance path 40 formed by the plurality of conveyance guide plates 39, and is stopped when it comes into contact with the registration roller pair 43.

On the other hand, when the start switch is pressed, the photoreceptor 17 rotates in the direction of the arrow in FIG. 2 and the surface thereof is uniformly charged by the charging roller 21. The photoreceptor 17 whose peripheral surface is charged is separated by the optical device 15
The content of the read copy document is written to carry an electrostatic latent image. The electrostatic latent image on the photoreceptor 17 is adhered with toner by the developing sleeve 21 of the developing device 23 and is visualized as a toner image.

The rotation of the photoreceptor 17 on which the toner image is formed is synchronized with the timing, and the registration clutch of the registration roller pair 43 is turned on to rotate the registration roller pair 43. Due to the rotation of the registration roller pair 43, the sheet P, which has hit the registration roller pair 43,
And the transfer device 25.

The paper P sent between the photoreceptor 17 and the transfer device 25 has the original image of the photoreceptor 17 transferred by the transfer device 25 and is conveyed to the fixing device 32. The document image of the sheet P conveyed between the fixing roller 30 and the pressure roller 31 of the fixing device 32 is fixed on the sheet P by the heat of the fixing roller 30 and the pressure of the pressure roller 31, and the document image is fixed. The discharged sheets P are discharged onto a discharge tray 45 and stacked.

Further, the toner remaining on the surface of the photoreceptor 17 after the transfer is scraped off by a cleaning blade 27 of a cleaning device 29, and is conveyed by a toner conveying roller 28 to a collection container or the like in the cleaning device 29 to be transferred to the photoreceptor. The surface of 17 is cleaned.

FIG. 2 is a perspective view showing the photoconductor driving unit. As shown in FIG.
Generally includes a photoreceptor 17, a gear train 51 as a drive transmission means, a drive motor 53 as a drive source, a flywheel 55 attached to the rotating shaft 18 of the photoreceptor 17, and a resonator 57. ing.

Generally, a drive motor 53 is used as a rotary drive source.
However, when the vibration at the rotation frequency of the drive motor 53 propagates to the housing of the copying machine 1 and coincides with the resonance frequency of the outer surface, the outer surface becomes an acoustic radiation surface and emits noise. Further, even when there is no resonance, the sound often leaks to the outside as a direct sound from the opening of the device such as the paper discharge portion. Further, a gear train 5 which is a drive transmission means of these drive systems.
1 generates noise due to meshing between the teeth of the gears 51a and 51b. The frequency at this time is determined by the product of the number of rotations of the gear 51 per unit time and the number of gear teeth z,
This vibration generation frequency is called the meshing frequency. In this way, noise due to vibration propagation is generated by the meshing vibration of the gear by the same mechanism as the motor vibration described above.

In order to reduce such noise, the present embodiment
In the embodiment, the energy is dissipated using the resonator 57.
ing. FIG. 3 is a schematic perspective view of the resonator 57.
You. As shown in FIG. 3, the resonator 57 is
A cavity member 59 having a gap 60 has a length L_H, Cross-sectional area S_Hof
A short tube 61 is provided. Also, one end of the short pipe 61
It is open and communicates the internal space of the hollow member 59 with the outside
are doing. The resonator 57 having such a shape is a Hertzholm
It is called a resonator, and f of equation (1) shown below _HOf
Produces a silencing effect at the sound frequency.

[0038]

(Equation 9) ... (1)

Therefore, the Helmholtz resonator 57
Volume V of subspace, length L of short pipe 61 _H, Cross-sectional area S_HPara
Frequency of noise that you want to reduce by changing the meter
Can be changed. In the present embodiment, FIG.
As shown in FIG. 4, the hollow member 5 of the Helmholtz resonator 57
9 slides inside the internal space 60 of the hollow member 59
A possible hollow slide member 63 is provided,
By sliding the material 63 in the direction of the arrow in FIG.
The volume V of the internal space 60 can be easily changed.

In the present embodiment, the volume V of the internal space 60 can be changed. However, the present invention is not limited to this. As shown in FIG. 5, a short pipe slide member 65 that can slide the short pipe 61 is used. The length L _H of the short pipe 61 can be changed or, as shown in FIG. 6, the cross-sectional area S _{H of the} short pipe 61 can be changed by an opening / closing slide member 67 slidable in a direction to open and close the opening of the short pipe 61. The length L _H and the cross-sectional area S _H of the short tube 61 can be easily changed in these configurations similarly to the configuration shown in FIG.

As described above, the resonator 57 according to the present embodiment is
Is the volume V of the internal space 60 of the hollow member 59 (or the short pipe 6).
Since the length L _H and the cross-sectional area S _H ) can be changed, the resonance frequency f _{H at} which the Helmholtz resonator 57 can reduce the noise level can be changed, and the change in the resonance frequency can be handled. the Helmholtz resonator 57 is a noise of the photosensitive member driving unit 50 can be reduced, in the present embodiment, the resonance frequency f _H of the resonator 57 is to match the rotation frequency f _m of the drive motor 53.

That is, the photoconductor driving unit 50 shown in FIG.
Has a drive motor 53 as a drive source as described above, and the drive motor 53 rotates at a constant speed. At this time, a noise corresponding to the rotation speed of the drive motor 53 is generated. Therefore, in the present embodiment, in order to reduce the frequency at which the noise effectively, the resonator 57 resonance frequency f _H that is determined by the formula (1) coincides with the rotational frequency f _m of the drive motor 53 Thus, the inner space 60 of the hollow member 59
(Or the length L _H or the cross-sectional area S _{H of} the short pipe 61).

Thus, noise from the drive motor 53 can be effectively reduced. In the present embodiment, coincides with the resonance frequency f _H, and the rotational frequency f _m (f _H =
Although was f _m) is, the resonant frequency number f _H and the rotational frequency f _m well be approximated (f _H ≒ f _m), even in this case, the reduction of noise from the drive motor 53 I can do it.

Further, in the photoconductor drive unit 50, there are a plurality of noise frequencies. In such a case, in order to reduce each noise frequency, the resonator 57 corresponding to each frequency is required. Is preferably provided. As described above, by providing a plurality of resonators 57 of the present embodiment, it is possible to reduce a plurality of remarkable noise frequency components generated in photoconductor drive unit 50, and to further reduce the noise of the device. .

For example, one of the noises from the photoconductor drive unit 50 is the noise from the gear train 51 that is driven to rotate by the drive motor 53 that rotates at a constant speed as described above. From the number of teeth of the product of the rotational speed and the gear of the gear 51a (51b), it is possible to calculate the meshing frequency f _G of the gear. That is, the rotational frequency (rotational speed of the units of the gear time Atari) of the drive motor 53 f _m and number of teeth z gear
Meshing frequency f _G of the gear to be calculated by the product (f _m × z) and can be calculated.

[0046] This meshing frequency f _G, in addition to the noise as a direct sound, cause and resonate with the copying machine 1, it is often the cause of the noise as indirect sound. Therefore, separately provided resonators 57 to reduce noise in the gear train 52, the resonant frequency f _H of the resonator 57 may be mesh matches the frequency f _G (or approximation), in this case The noise from the gear train 51 can be effectively reduced to several.

Next, another embodiment will be described. In the description, the same parts as those described above are denoted by the same reference numerals, and the description thereof will be omitted.

FIG. 7 is a perspective view showing a photoconductor drive unit according to the second embodiment. In the second embodiment, as shown in FIG. 7, the drive from the drive motor 53 is transmitted to the rotation shaft 18 of the photoconductor 17 by a timing belt (drive transmission means) 69, so that the photoconductor 17 is driven to rotate. This is different from the first embodiment.

When the timing belt 69 is used as in the present embodiment, the timing belt 69 may generate a string vibration at the time of rotational driving, which may cause noise. FIG. 8 shows a schematic diagram of the string vibration. As shown in FIG. 8, in the section of the length L of the timing belt 69, the primary (n = 1) and the secondary (n =
2) String vibration is caused as in the third order (n = 3). The string vibration when the unit length weight of the timing belt 69 m, belt length L _b, a belt tension T _b, to generate a string vibration in the string vibration frequency f _b as the following formula (2).

[0050]

(Equation 10)

Therefore, in order to effectively reduce the noise caused by the string vibration of the timing belt 69, in the present embodiment, the resonance frequency f _H of the Helmholtz resonator 57 is used.
Is set so as to match or approximate the string vibration frequency f _b of the timing belt 69,
9 is effectively reduced.

FIG. 9 is a block diagram schematically showing the vicinity of a resonator shape control device for controlling a resonator according to the third embodiment. In the third embodiment, in the resonator 57, the volume V of the internal space 60, the length L _H of the short tube 61, and the cross-sectional area S _H can be changed by the respective slide members 63, 65, 67. I have.

[0053] Further, in the present embodiment, as shown in FIG. 9, the volume V of the internal space 60, the length L _H of the short pipe 61, and resonator shape control apparatus for changing the cross-sectional area S _H (control means)
And a noise detection device 73 for detecting noise generated in the photoconductor drive unit 50, and a resonator parameter calculation device 75 for specifying the frequency _{fk of} the noise detected by the noise detection device 73. In the present embodiment, the noise detecting device 73 and the resonator parameter calculating device 75 constitute a frequency detecting section (frequency detecting means) 77.

In the present embodiment, the photosensitive member driving unit 5
The noise generated at 0 is detected by a noise detection device 73 such as a microphone, and the obtained data is subjected to frequency analysis by FFT (fast Fourier transform) by a resonator parameter calculation unit, and a remarkable frequency component which is a problem is detected. Identify. Then, the volume V of the internal space 60 (or the length L _H or the cross-sectional area of the short pipe 61) is adjusted so that the vibration reduction frequency f _H of the Helmholtz resonator matches the frequency f _k specified here. The parameters of S _H ) are determined, and the resonator shape controller 71 determines and controls the shape of the Helmholtz resonator 57 based on the data.

Therefore, in the third embodiment, the environmental change,
Even if there is a variation due to the configuration of the copying machine 1 or the like, the Helmholtz resonator 57 may be used in accordance with each individual situation.
Can be optimized, and the noise can be further reduced. Further, it is possible to easily cope with a change in the driving speed due to a difference in the print mode.

The present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention. For example, in the present embodiment, the copier 1 has been described as an example, but the present invention is not limited thereto.
Similar functions and effects can be obtained by applying the present invention to an image forming apparatus such as a facsimile machine or a multifunction machine.

[0057]

According to the first aspect of the present invention, a resonator having a short tube and a hollow member is provided, and at least one of the volume of the internal space of the hollow member, the length of the short tube, and the sectional area of the short tube is provided. Since it is possible to change one of them, the frequency that can be reduced can be changed, so that the resonator becomes a Helmholtz resonator (Helmholtz vibration absorber) corresponding to various noise frequency bands, which leads to a reduction in noise.

[0058] Also, the frequency f _H of the noise is most reduced by the Helmholtz resonator, by identical or close with the rotation frequency f _m of the drive motor, the motor rotation of remarkable noise generated in the image bearing member driving unit The sound can be effectively reduced, and a low-noise photoconductor drive unit can be obtained.

According to the second aspect of the present invention, a resonator having a short tube and a hollow member is provided, and at least one of the volume of the internal space of the hollow member, the length of the short tube, and the cross-sectional area of the short tube is changed. Since it is possible, the frequency that can be reduced can be changed, so that the resonator becomes a Helmholtz resonator corresponding to various noise frequency bands, leading to low noise.

[0060] Also, the frequency f _H of the noise is most reduced by the Helmholtz resonator, the rotational frequency of the drive motor (rotational speed of the units of the gear time Atari) f _m and the number of teeth z in the gear of the drive transmission means by matching or approximating the meshing frequency f _{G =} f m · _z gear calculated by the product, it is possible to effectively reduce the meshing sound of the striking noise of gears generated in the image bearing member driving unit A low-noise photoconductor drive unit can be obtained.

According to the third aspect of the present invention, a resonator having a short tube and a hollow member is provided, and at least one of the volume of the internal space of the hollow member, the length of the short tube, and the cross-sectional area of the short tube is changed. Since it is possible, the frequency that can be reduced can be changed, so that the resonator becomes a Helmholtz resonator corresponding to various noise frequency bands, leading to low noise.

When the frequency f _H at which noise is reduced most by the Helmholtz resonator matches or approximates the string vibration frequency f _b , one of the remarkable noises generated in the image carrier driving unit is obtained. Therefore, the string vibration sound of the timing belt can be effectively reduced, and a low-noise photoconductor drive unit can be obtained.

According to a fourth aspect of the present invention, there is provided a resonator including a short tube and a hollow member, and at least one of the volume of the internal space of the hollow member, the length of the short tube, and the cross-sectional area of the short tube is changed. Since it is possible, the frequency that can be reduced can be changed, so that the resonator becomes a Helmholtz resonator corresponding to various noise frequency bands, leading to low noise.

Further, the control means adjusts the frequency f _{H at} which noise is reduced most by the Helmholtz resonator to the internal space of the cavity member in the resonator so as to match the frequency f _k of the noise detected by the frequency detection means. By changing at least one of the volume V, the length of the short pipe LH, and the cross-sectional area SH of the short pipe,
It is possible to realize a resonator that can cope with a difference in speed depending on a printing mode, a speed change due to an environmental change, and the like, and thus can reduce noise actively.

According to a fifth aspect of the present invention, a low-noise image forming apparatus can be obtained by providing the image carrier unit according to any one of the first to fourth aspects.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing a copying machine according to the present invention.

FIG. 2 is a perspective view illustrating a photoconductor driving unit according to the first embodiment.

FIG. 3 is a perspective view showing a resonator.

FIG. 4 is a sectional view of the resonator shown in FIG. 3;

FIG. 5 is a perspective view showing a resonator according to a modification.

FIG. 6 is a perspective view showing a resonator according to a modification.

FIG. 7 is a perspective view illustrating a photoconductor driving unit according to a second embodiment.

FIG. 8 is a diagram illustrating string vibration of a timing belt.

FIG. 9 is a block diagram illustrating a noise detection unit and a resonator shape control device according to a third embodiment.

[Explanation of symbols]

 1 Copier 17 Photoconductor (Image Carrier) 50 Photoconductor Drive Unit (Image Carrier Drive Unit) 51 Gear Train (Drive Transmission Means) 53 Drive Motor 57 Resonator 59 Cavity Member 60 Internal Space 61 Short Pipe 69 Timing Belt ( Drive transmission means) 71 resonator shape control device (control means) 77 noise detection unit (noise detection means)

Claims (5)

[Claims] 1. An image carrier driving unit in which a drive from a drive motor is transmitted to an image carrier via a drive transmitting means, whereby the image carrier is rotationally driven. The vessel includes a hollow member having a predetermined internal space, and a short pipe communicating the internal space of the hollow member with the outside. The volume of the internal space of the hollow member, the length of the short pipe, and the cutoff of the short pipe are provided. At least one of the areas
The volume of the internal space of the hollow member is V, and the length of the short pipe is L _H
And then, the cross-sectional area of the short pipe and S _H, when the speed of sound and is c,
The resonance frequency f of the resonator determined by the following equation (1)
_H is an image carrier driving unit, characterized in that matches or approximates the rotational frequency f _m of the drive motor. (Equation 1) 2. An image carrier driving unit in which a drive from a drive motor is transmitted to an image carrier via a drive transmitting means, whereby the image carrier is rotationally driven. The vessel includes a hollow member having a predetermined internal space, and a short pipe communicating the internal space of the hollow member with the outside. The volume of the internal space of the hollow member, the length of the short pipe, and the cutoff of the short pipe are provided. At least one of the areas
The volume of the internal space of the hollow member is V, and the length of the short pipe is L _H
And then, the cross-sectional area of the short pipe and S _H, when the speed of sound and is c,
The resonance frequency f of the resonator determined by the following equation (1)
_H is a meshing frequency f _G determined by the product of the number of rotations of the gear of the drive transmission unit per unit time and the number of gear teeth.
An image carrier drive unit characterized in that: (Equation 2) 3. An image carrier driving unit in which a drive from a drive motor is transmitted to an image carrier via a drive transmitting means, whereby the image carrier is rotationally driven. The vessel includes a hollow member having a predetermined internal space, and a short pipe communicating the internal space of the hollow member with the outside. The volume of the internal space of the hollow member, the length of the short pipe, and the cutoff of the short pipe are provided. At least one of the areas
The volume of the internal space of the hollow member is V, and the length of the short pipe is L _H
And then, the cross-sectional area of the short pipe and S _H, when the speed of sound and is c,
The resonance frequency f of the resonator determined by the following equation (1)
_H is an image carrier driving unit, characterized in that matches or approximates the string vibration frequency f _b of the timing belt drive transmission means. (Equation 3) 4. An image carrier driving unit in which a drive from a drive motor is transmitted to an image carrier via a drive transmission means, whereby the image carrier is rotationally driven. A frequency detecting unit that detects a frequency _fk of noise generated by the body driving unit; and a control unit that controls a resonance frequency of the resonator based on a detection signal from the frequency detecting unit. The resonator has a predetermined internal space. And a short pipe communicating between the internal space of the hollow member and the outside, and at least one of the volume of the internal space of the hollow member, the length of the short pipe, and the cross-sectional area of the short pipe can be changed. Where V is the volume of the internal space of the hollow member, and L _{H is} the length of the short pipe.
And then, the cross-sectional area of the short pipe and S _H, when the speed of sound and is c,
Control means, a resonance frequency f _H of the resonator is determined by the following equation (1), to match the frequency f _k detected by the frequency detection means, the volume of the internal space of the hollow member in the resonator V , short tube length L _H, and the short pipe cross-sectional area S _H
An image carrier driving unit characterized in that at least one of them is changed. (Equation 4) 5. An image forming apparatus comprising the image carrier driving unit according to claim 1.