JP2002139959A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus in which the uneven rotation of a photoreceptor due to the influence of a molded gear and the reinforcing rib of a pulley is prevented. SOLUTION: The frequency by the rib interval of the gears (101, 102 and 103) and the pulleys (104 and 105) obtained until the photoreceptor (4) is driven and the frequency of one rotation of the gear (101) formed on an output shaft coaxial to a main motor (1) and the main motor (1) are unified to nearly the same frequency by considering the shape of the rib respectively, so that the uneven rotation of the photoreceptor (4) is prevented from being caused with a plurality of frequencies. Furthermore, the uneven rotation of the photoreceptor (4) is reduced all the more by providing an optimized fly wheel (5) coaxially to the photoreceptor (4).

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 using a drive device used in an electrophotographic process, such as a copying machine, a facsimile, a printer, and the like.

[0002]

2. Description of the Related Art Conventionally, a driving device in an image forming apparatus generally uses a brushless motor as a driving source, decelerates through several gear groups, and drives a photosensitive member. It is effective to use a molded article made of resin for the gear group among them, because it is inexpensive in terms of cost and noise. In the case of a molded article made of resin, several ribs are formed at regular intervals in order to ensure the strength of the tooth surface.
However, when the ribs are formed, the tooth surfaces of the ribs with and without the ribs are shrunk or squeezed by the influence of the molding, thereby deteriorating the gear accuracy. The influence of sinks and tensions caused by the ribs may appear on the image as pitch unevenness at the intervals between the ribs.

[0003] As an example of the intensity of unevenness, Table 1 shows the frequency when a rib is formed without considering the gear rib pitch. In this case, the rotation unevenness of the photoconductor is measured and F
FIG. 2 shows the results of the FT analysis. <Table 1> According to Table 1 and FIG. 2, the frequency of the main motor (1) per rotation is 19.2 Hz, the frequency of the ribs of the gear (101) is 37.4 Hz, 32.4 Hz, and half the frequency is 18.1 Hz.
7 Hz, 16.2 Hz, frequencies 23.2 Hz, 27.1 Hz by the ribs of the gear (103), and half the frequency 1
3.6 Hz, frequency 1 by rib of pulley (105)
5.3 Hz appears prominently. Actually, even on the image, unevenness which is considered to be each frequency can be confirmed in the halftone portion. In this case, if the condition is set so that all the protruding frequencies can be eliminated by the effect of the inertia, the inertia must be increased until the effect appears at the lowest protruding frequency of 13.6 Hz.

In Japanese Patent Application Laid-Open No. Hei 8-115010, the relationship between the number of gear teeth and the number of ribs is such that the common divisor is one.
However, when the rotation unevenness of the photoreceptor is actually measured, unevenness at a frequency close to the rib pitch should be confirmed, and the measure was incomplete. JP 7
In Japanese Patent Application Laid-Open No. 209942, the reduction ratios of the gears are all integral multiples. However, since the frequency due to one rotation of the main motor is different from the frequency due to the rib pitch, unevenness in each frequency band should be confirmed. Was incomplete.

[0005]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in view of the above-mentioned problems, and the frequency due to the influence of the reinforcing rib of the molded gear is made substantially the same, and the photosensitive member is used at a plurality of frequencies. It is an object of the present invention to provide an image forming apparatus that prevents rotation unevenness from occurring. It is still another object of the present invention to provide an image forming apparatus in which the frequency of one rotation of a main motor as a driving source and the frequency of the influence of the reinforcing rib of a forming gear are unified, and the rotation of the photosensitive member does not become uneven at plural frequencies. And It is still another object of the present invention to provide an image forming apparatus that reduces the unevenness of rotation of the photoconductor due to the unevenness of one rotation of the main motor and the influence of the rib of the forming gear, and shows stable image quality without pitch unevenness.

[0006]

In order to solve the above-mentioned problems, the invention according to the first aspect of the present invention considers the shape of a reinforcing rib in a molded gear or a pulley, thereby reducing the frequency due to the rib interval between the gear and the pulley. Means of unifying almost the same
An image forming apparatus including According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the frequency of at least one of the forming gears and the pulleys and the frequency of one rotation of the main motor as a driving source are substantially unified. An image forming apparatus comprising: According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, a flywheel whose outer shape and thickness are adjusted is provided coaxially with the photoconductor, thereby reducing rotation unevenness of the photoconductor. An image forming apparatus including

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described. According to FIG. 1, the main motor (1) as a driving source
The gear (101), which is coaxial with the rotor (1), is rotationally driven at a rotational speed of 1151.96 rpm calculated in accordance with the linear speed of the photoconductor (4), and transmits power to the large gear of the gear (102).
The rotation speed of the gear (102) at this time is 149.61 rpm, calculated from the gear ratio. Also, this gear is 2
The driving is transmitted to the gear (103) by the small gear, and the speed is reduced to 115.95 rpm. Further, the gear (10
The pulley (104) coaxial with 3) is also driven to rotate at the same rotational speed. The pulley (105) is decelerated to 57.24 rpm from the pulley (104) by the timing belt (2), and the drum shaft (3) coaxial with the pulley (105) is rotationally driven. Is driven to rotate. The above is the details of the drive train from driving the photoconductor (4) by the main motor (1).

Table 2 shows an example of the present embodiment. In this case, the rotation unevenness of the photoconductor (4) is measured and
FIG. 3 shows the results of T analysis. <Table 2> According to Table 2 and FIG. 3, the frequency of 19.2 Hz due to the unevenness of one rotation of the main motor (1) and the rib pitch from the gear (101) to the pulley (105) is larger than that in Table 1 above. Although it does, it does not protrude at other frequencies. No unevenness other than 19.2 Hz can be confirmed on the image. Therefore, the condition of inertia is set to 1
If 9.2 Hz can be reduced, it is possible to reduce most of the rotation unevenness caused by the drive train from the main motor (1) to the drive of the photoconductor (4).

Specifically, a flywheel (5) is arranged on the axis of the drum shaft (3) in FIG. 1, and the flywheel (5) is moved until the unevenness disappears in the image at 19.2 Hz. What is necessary is just to adjust by outer diameter and board thickness. FIG. 5 shows data of drum rotation unevenness when the flywheel (5) was optimized to reduce 19.2 Hz. According to this, the low frequency side is protruding, but the frequency is reduced at 19.2 Hz. Also, the pitch unevenness has disappeared on the image.

FIG. 4 shows the specific rib shape of the gear in this embodiment. For example, in the case of the gear (102), in the case of Table 1, the large gear side is divided into 15 equal parts every 24 °,
The small gear side was divided into 13 equal parts every 27.7 °. In the case of Table 2, in order to make the frequency of the main rib pitch close to 19.2 Hz, both the large gear and the small gear were 46. Seven ribs are arranged every 8 °, and the other one is arranged in the middle. Similarly, the gear (103) is also provided with main rib pitches at intervals of 36.2 ° so as to approach 19.2 Hz. The following gears and pulleys also determine the rib spacing in accordance with 19.2 Hz.

[0011]

As described above, in the image forming apparatus according to the first aspect, the frequencies generated by the influence of the reinforcing ribs of the molding gear are unified to prevent the rotation of the photosensitive member from being caused at a plurality of frequencies. It is possible to do. In the image forming apparatus according to the second aspect, it is possible to unify the frequency generated by the influence of the rotation of the motor and the reinforcing rib of the formed gear, and to prevent the rotation of the photosensitive member from being caused at a plurality of frequencies. In the image forming apparatus according to the third aspect, it is possible to reduce the rotation unevenness of the photoconductor due to the unevenness of one rotation of the motor and the influence of the rib of the forming gear, and to provide a stable image quality without pitch unevenness.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a photoconductor and a driving source.

FIG. 2 is a characteristic diagram showing rotation unevenness of a conventional photoconductor.

FIG. 3 is a characteristic diagram illustrating rotation unevenness of a photoconductor in a practical embodiment of the present invention.

FIG. 4 is a view showing a shape of a rib of a gear in a practical embodiment of the present invention.

FIG. 5 is a characteristic diagram showing rotation unevenness of a drum in a practical mode of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main motor 2 Timing belt 3 Drum shaft 4 Photoconductor 5 Flywheel 101,102,103 Gear 104,105 Pulley

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) F16H 37/02 F16H 37/02 C 3J049 55/06 55/06 55/14 55/14 55/40 55 / 40 G03G 15/00 550 G03G 15/00 550

Claims (3)

[Claims] 1. A photoconductor, a drive source for driving the photoconductor, and a gear group and a pulley group that are decelerated from the drive source and drive the photoconductor, and at least two of the gear group and the pulley group. In the image forming apparatus, which is a molded product made of resin and is a gear or a pulley having ribs for reinforcing the tooth surface, a frequency (N / 60 × R; here, N represents the number of rotations, and R represents the number of ribs.) Hz is substantially the same frequency. 2. The image forming apparatus according to claim 1, wherein the main motor as a driving source has a gear formed on an output shaft coaxial with the main motor, and at least one of the gear having the rib and the pulley. An image forming apparatus, wherein a frequency based on one rib interval and a frequency (N / 60) of one rotation of a main motor as a driving source are substantially the same. 3. The image forming apparatus according to claim 1, wherein a flywheel is provided coaxially with said photoconductor.