JP2003014088A - Drive transmission gear - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce vibration of image forming apparatus, improve image quality,
A power transmission gear capable of reducing noise and the like. A drive transmission gear 101 for transmitting rotational power from a power source of an image forming apparatus for an electrophotographic process employing a laser to an exposure process to a photosensitive drum is a member for improving rigidity, and has a tooth surface on an outer periphery. A rigid member 201 having concavities and convexities in the same phase as above is attached.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission gear of an apparatus for forming an image using an electrophotographic process.

[0002]

2. Description of the Related Art Known laser beam printers (hereinafter referred to as L
(Abbreviated as BP) will be described with reference to FIG.

FIG. 19 shows a conventional LB for the present invention.
FIG. 6 is a cross-sectional view of P, and the transfer material P stored in a paper feed cassette 3101 is fed by a paper feed roller 3102 and conveyed by a conveyance roller 3103. And
The transfer material P is conveyed in synchronization with the photosensitive drum 3104,
The toner image on the photosensitive drum 3104 is transferred to the transfer roller 3105.
Then, the toner image is fixed on the transfer material P by the fixing device 3106, and then the transfer material P is ejected to the paper ejection tray 109 by the fixing paper ejection roller 3107.

On the other hand, the laser beam scanner unit 31
A latent image is formed on the photosensitive drum 3104 by 10, and the latent image is developed by the toner supplied by the developing device and visualized as a toner image. Incidentally, 3111 is the photosensitive drum 31.
04 is a charging roller that uniformly charges the top.

FIG. 20 is a plan view of a laser beam scanner unit 3110 of LBP, which is a laser unit 320.
The laser beam emitted from the laser beam No. 1 reaches the scanning mirror 3203 via the lens 3202. The laser beam reflected by the scanning mirror 3203 rotating at a high rotational speed is reflected by the reflecting mirror 32 via the imaging lens 3204.
The photosensitive drum 3104 shown in FIG.
And a latent image is formed on the rotating photosensitive drum 3104.

While this process is taking place, FIG.
If mechanical vibrations are transmitted from the main motor 3301 to the gear 3302 that transmits rotational power to the photosensitive drum 3104, the rotation uniformity of the photosensitive drum 3104 is deteriorated, and as a result, the media is rotated. It will adversely affect the image formed above.

[0007]

[Problems to be Solved by the Invention] LBP released in recent years
Then, the size of the device tends to be smaller, and the printing speed to the media tends to be faster. In other words, the rigidity of the device is smaller, the vibration energy due to various operations is larger, and the frequency shifts to the high frequency band. Therefore, the vibration mode, which was not excited in the previous LBP, is excited with considerable accuracy in recent years, resulting in unpleasant noise and disturbance to the image as an output result. The noise and the disturbance to the image are caused by the gear for power transmission, and the insufficient rigidity of the gear causes the problem to a large extent.

In the case of a disk-like shape such as a power transmission gear, a normal membrane mode (a mode in which the gears vibrate in the same phase all around) appears as the first-order mode in the lowest frequency band, and the next second-order mode. The mode has a node in the direction perpendicular to the normal line of the circumference, and the phase varies depending on the position of the circumference, and the nodes in the direction perpendicular to the normal line of the circumference increase as the order becomes higher. Therefore, first, in order to increase the rigidity (modal equivalent rigidity) for the primary mode, it is necessary to increase the bending rigidity of the circle in the radial direction. To increase the modal equivalent rigidity for the secondary modes and above, It is necessary to increase the bending rigidity in both the radial direction and the circumferential direction of the circle. As a measure for improving the rigidity, conventionally, ribs have been provided in a resin gear. Also, as a countermeasure by changing the material, a metal gear was adopted.

However, in the case of a resin type gear, a great effect is exhibited unless the rib is extended to the back side of the tooth surface.
If the ribs are extended to that extent, there is a problem that the tooth surface accuracy is adversely affected by the shrinkage after molding.

When a metal gear is used, grease is indispensable for the meshing portion of the gear, which leads to an increase in manufacturing cost.

Further, in recent printer product development, functional parts and parts, large-sized molded parts that require mold cost, and high-precision parts are commonly used for a plurality of products (for example, products whose print speed is changed). It is being diverted.

First, an optimum gear is designed in consideration of the cost and the specifications so that the bending rigidity in the radial direction and the bending rigidity in the circumferential direction of the driving force transmitting gear will not adversely affect the image. , Product A incorporating it is completed.

As a product of the next generation, when a completely similar gear is applied to develop a product B having a printing speed faster than that of the product A, the driving force transmitting gear vibrates greatly at the printing speed of the product B. This may cause a problem that the image is adversely affected.

In the case of the product B, this is because the gear meshing frequency or the frequency of the vibration energy of the other vibration source and the natural frequency of the gear are close to or coincide with each other. No problem occurs.

As a countermeasure against the phenomenon occurring in the product B, conventionally, a new part (gear in this example) is newly designed to solve the problem. If a mechanical component having a different shape is newly manufactured, the manufacturing cost will be increased due to the manufacturing of the mold and the change of the manufacturing process. In particular, important functional parts, high-precision parts, and large parts not only lead to cost increase, but also have a great influence on product quality.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power transmission gear that can reduce vibration of an image forming apparatus, improve image quality, and reduce noise. To provide.

[0017]

To achieve the above object, the present invention provides a drive transmission gear for transmitting rotational power from a power source of an image forming apparatus of an electrophotographic process which employs a laser to an exposure process to a photosensitive drum. In the above item 1, a member for improving rigidity is attached to the outer circumference of the member, which has unevenness in the same phase as the tooth surface.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

<First Embodiment> A first embodiment of the present invention will be described with reference to FIGS. 1 is a front view of a power transmission gear of the image forming apparatus according to the first embodiment of the present invention, FIG. 2 is a sectional view of the gear, and FIG. 3 is a rear view of the gear.

The power transmission gear 101 according to the present invention is insert-molded together with the rigid member 201.

In FIG. 4, the rigid member 201 is not attached.
It is a figure which shows the vibration displacement transfer function in a case. In Figure 4
In the product A, the meshing frequency of the gear 101 is
ω_AAnd the natural frequency of the gear 101 in the state of FIG.
Ω₁ And In this case, ω _A Is ω₁ More fairly low frequencies
It exists in several bands and the gear 1
The vibration caused by the meshing of 01 is not amplified, resulting in
The image on the transfer material P output by the product A as
It will be less disturbed.

[0022] However, the same product A and mechanical construction, if you try to produce a product B1 raising the printing speed, next omega _B the gear 101 meshing frequency of the product B in FIG. 4, the gear 101 natural oscillation When the numbers ω ₁ and ω _B exist in a very close frequency band, the vibration caused by the meshing of the gear 101 is greatly amplified by the vibration mode having the natural frequency ω ₁ , and as a result, the product B As a result, the image on the transfer material P that is output due to the disturbance becomes noticeable, and the image quality of the product B1 becomes extremely low.

Therefore, as shown in FIG. 1 to FIG.
When 201 is attached to the gear 101, the vibration displacement transfer function
Changes as shown in FIG. As shown in FIGS.
By attaching the rigid member 201 to the gear 101,
The natural frequency of the gear 101 is ω as shown in FIG.₁ Move to
Of the gear 101 of the product B_B Is ω
₁ ′ Is located in a considerably lower frequency band than
₁ Is amplified by the vibration mode where ’is the natural frequency
The product B2 has a good image quality.
It will be Le.

When producing a product having a printing speed higher than that of the product B2, good image quality can be obtained by increasing the plate thickness of the rigid member 201 attached to the gear 101 in FIG. it can.

Further, as shown in FIG. 6, the rigid member 201 has irregularities of the same phase as the wavefront shape of the gear 101 in the rotational direction, which allows the outer periphery of the rigid member 201 and the gear 101 to be separated. The thickness of the filling material filled in the clearance of the tooth surface becomes constant, and the gear 1 due to the contraction of the material after molding
The deterioration of the tooth flank precision of No. 01 can be suppressed to the minimum, and the image quality can be kept good. Further, the change in rigidity in the circumferential direction can be suppressed to a minimum, and the shape of the vibration mode of the gear 101 is only a mode peculiar to a simple circular plate such as a film mode, and measures can be taken by increasing the rigidity. Become.

As described above, according to the present embodiment, even when the print speeds of the image forming apparatuses are different, the gears that require high precision can be used over a plurality of products. Since the power transmission gear is a component that transmits the rotational power of the rotating member, its accuracy directly leads to the good or bad rotation accuracy. Therefore, the cost of the mold is high, and the advantage that a high-performance, high-priced product can be used by a plurality of products is very large. In addition, this gear structure reduces vibration while using a simple structure in which a rigid member is mounted after using common parts.
It is possible to realize a high-performance image forming apparatus with high image quality and low noise. Since the rigid member 201 is made of a single material, the manufacturing process is simple and the cost is low. Furthermore, since the structure is simple, the rigid member 20
The simulation of the change in natural frequency when the No. 1 is attached can be performed easily and with high accuracy, and the development efficiency is good.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIGS.

In this embodiment, the rigid member 201 inserted into the power transmission gear 101 described in the first embodiment is insert-molded together with the rigid member 801 having an increased inner diameter without changing the outer diameter. The drive force transmitting gear 701 is adopted.

FIG. 10 is a diagram showing a vibration displacement transfer function of the power transmission gear in the rotation axis direction when the rigid member 801 is not attached.

[0030] When incorporating the meshing frequency of the power transmission gear to the product of omega _C, omega _C because it has close to the characteristic frequency omega ₁ of the rotary shaft axis of the power transmission gear, the power transmission gear Periodic disturbances of the meshing pitch will appear in the resulting printed image.

In this case, as shown in FIGS. 7 to 9, by molding the power transmission gear 701 together with the rigid member 801, the vibration displacement transfer function of the power transmission gear 701 becomes as shown in FIG. In the vibration mode having the natural frequency of ω ₁ in FIG. 10, the rigid member 801 acts as an increase in the mode equivalent mass, and the natural frequency ω ₁ changes to ω ₁ ′ in the low frequency band. On the other hand, for the vibration mode having the natural frequency of ω _{2 in} FIG. 10, the rigid member 801 acts as an increase in the mode equivalent rigidity, and therefore the natural frequency ω
₂ moves to ω ₂ 'in the high frequency band. (∵ω _n0 = √ (k / m) ω _n0 : undamped natural frequency,
(m: modal equivalent mass, k: modal equivalent mass rigidity) As a result, the gear meshing frequency ω _C is out of the band amplified by any vibration mode, and as a result, the image output by the product C has little disturbance. Becomes

Further, as in the first embodiment, as shown in FIG. 12, the rigid member 801 has unevenness of the same phase as the wavefront shape of the gear 101 in the rotational direction, which allows the rigidity to be increased. The thickness of the filling material filled in the clearance between the tooth surface of the outer periphery of the member 801 and the gear 701 becomes constant, and the deterioration of the tooth surface accuracy of the gear 701 due to the contraction of the material after molding can be minimized. , The image quality can be kept good. Further, the change in rigidity in the circumferential direction can be suppressed to a minimum, and the vibration mode of the gear 701 has only the mode peculiar to a simple circular plate such as the film mode, so that it is possible to take measures by increasing the rigidity. .

Further, according to the present embodiment, the first embodiment
Since the weight of the rigid member 801 is lighter than that of the embodiment, the effect that the total driving force transmission gear 701 can be further lightened can be obtained.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIGS. Incidentally, FIG.
Is a front view of the power transmission gear 1301 according to the present embodiment, FIG. 14 is a sectional view, and FIG. 15 is a rear view.

Reference numeral 1401 is a rigid member, and a vibration damping steel plate having a high damping coefficient is used for this rigid member 1401. FIG. 16 is a diagram showing a vibration displacement transfer function when the rigid member 1401 is not attached. On the other hand, as shown in FIGS.
17 shows the vibration displacement transfer function in the case where the power transmission gear 1301 is molded together with 1.

Further, as shown in FIG. 18, the rigid member 1401 has irregularities in the same phase as the wavefront shape of the gear 1301 in the rotational direction, and this allows the outer periphery of the rigid member 1401 and the gear 1301 to be separated. The thickness of the filling material filled in the clearance of the tooth surface becomes constant, deterioration of the tooth surface accuracy of the gear 1301 due to contraction of the material after molding can be suppressed to the minimum, and good image quality can be maintained. it can. And
The change in the rigidity in the circumferential direction can also be suppressed to a minimum, and the vibration mode of the gear 1301 has only the mode peculiar to a simple circular plate such as the film mode, and the countermeasure can be taken by increasing the rigidity.

The power transmission gear 1101 is particularly effective in improving the image quality when the vibration energy of the image forming apparatus has a wide frequency range.

[0038]

As is apparent from the above description, according to the present invention, the drive transmission gear for transmitting the rotational power from the power source of the image forming apparatus of the electrophotographic process employing the laser to the exposure process to the photosensitive drum. In order to improve rigidity, a rigid member having irregularities in the same phase as the tooth surface is attached to the outer circumference, so that the image forming apparatus can be reduced in vibration, image quality, and noise. The effect that it can be achieved is obtained.

[Brief description of drawings]

FIG. 1 is a front view of a power transmission gear according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the power transmission gear according to the first embodiment of the present invention.

FIG. 3 is a rear view of the power transmission gear according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a vibration displacement transfer function when a power transmission gear to which a rigid member is not attached is used.

FIG. 5 is a diagram showing a vibration displacement transfer function when the power transmission gear according to the first embodiment of the present invention is used.

FIG. 6 is an enlarged view of a power transmission gear outer peripheral portion according to the first embodiment of the present invention.

FIG. 7 is a front view of the power transmission gear according to the second embodiment of the present invention.

FIG. 8 is a sectional view of a power transmission gear according to a second embodiment of the present invention.

FIG. 9 is a rear view of the power transmission gear according to the second embodiment of the present invention.

FIG. 10 is a diagram showing a vibration displacement transfer function when a power transmission gear to which a rigid member is not attached is used.

FIG. 11 is a diagram showing a vibration displacement transfer function when the power transmission gear according to the second embodiment of the present invention is used.

FIG. 12 is an enlarged view of an outer peripheral portion of a power transmission gear according to the second embodiment of the present invention.

FIG. 13 is a front view of a power transmission gear according to a third embodiment of the present invention.

FIG. 14 is a sectional view of a power transmission gear according to a third embodiment of the present invention.

FIG. 15 is a rear view of the power transmission gear according to the third embodiment of the present invention.

FIG. 16 is a diagram showing a vibration displacement transfer function when a power transmission gear to which a rigid member is not attached is used.

FIG. 17 is a diagram showing a vibration displacement transfer function when the power transmission gear according to the third embodiment of the present invention is used.

FIG. 18 is an enlarged view of an outer peripheral portion of a power transmission gear according to the third embodiment of the present invention.

FIG. 19 is a sectional view of a conventional image forming apparatus.

FIG. 20 is a plan view of a laser beam scanner unit.

FIG. 21 is a side view of a power transmission unit of a conventional image forming apparatus.

[Explanation of symbols]

101, 701, 1301 power transmission gear 201, 801, 1401 Rigid member 3104 Photosensitive drum

Claims (2)

[Claims] 1. A drive transmission gear for transmitting rotational power from a power source of an image forming apparatus of an electrophotographic process that employs a laser to an exposure process to a photosensitive drum, which is a member for improving rigidity and has teeth on its outer periphery. A drive transmission gear, characterized in that a rigid member having irregularities in the same phase as the surface is attached. 2. The power transmission gear according to claim 1, wherein the rigid member is made of at least one material, and one of them is made of a material having vibration damping performance.