JPH0380264A - Drum driving device - Google Patents

Abstract

PURPOSE:To decrease the misregistration on the outer periphery of a drum by setting the number of teeth of speed reducing gears in such a manner that the frequency per the tooth bearing thereof is equal to or larger than the frequency of the rotation of a drum driving motor. CONSTITUTION:The drum driving motor 20 is controlled to the constant rotation by a motor control means. The rotation of the drum driving motor 20 is reduced in speed by the gears 32, 34, 42, 44 and is transmitted to the drum 10. The number of teeth of the speed reducing gears 32, 34, 42, 44 for drum driving is set at adequate values and the frequency per tooth of the gear is shifted from the rotating frequency of the drum driving motor 20 to a high frequency side. The misregistration on the outer periphery of the drum is suppressed to a small level.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drum drive device, and more particularly, to a drum drive device that drives a photosensitive paper conveyance drum or a photosensitive drum in an electrophotographic copying device. .

[Prior Art] Conventionally, in an electrophotographic copying apparatus, in order to rotate a photosensitive paper transport drum or a photosensitive drum (hereinafter collectively referred to as a drum) at a constant speed, the rotation of a motor that drives the drum is controlled to a constant rotation. , Semi-closed loop control is performed in which rotation is transmitted to the drum using gears. The motor rotation speed is generally designed to be high compared to the rotation speed required for the drum, so it is normally reduced by gears, but due to problems such as gear accuracy and strength, the motor rotation speed is Since the possible reduction ratio is about 115 to 1/10, if there is a large difference between the rotation speeds of the drum and the motor, two or three steps of reduction have been performed.

At this time, gears with a relatively small number of teeth were used for reasons such as strength and ease of manufacture.

[Problems to be Solved by the Invention] In a drive force transmission mechanism using gears, the impact when the teeth mesh causes speed unevenness in the rotation of the driven body. In a drum drive device, vibrations caused by tooth contact cause uneven rotation speed of the drum, which causes exposure unevenness on the photosensitive paper or the photosensitive drum. This exposure unevenness appears as periodic density unevenness after development, and for example, when a solid original is copied, dark and light stripes as shown in FIG. 2 occur.

In a gear with a small number of teeth, the tooth contact frequency is low, and the positional deviation (time integral of speed unevenness) on the outer circumference of the drum is larger than the high frequency speed unevenness.

Especially in gear trains that have two or three stages of deceleration, the second stage.

Since the third stage gear rotates at a low speed, there is a problem in that the positional deviation on the outer periphery of the drum due to the tooth contact becomes large.

The present invention has been made to solve the above-mentioned problems, and by setting the number of teeth of the reduction gear for drum drive to an appropriate value, the tooth contact frequency of the gear can be adjusted to the rotational frequency of the drum drive motor. The purpose is to shift to a higher frequency side and suppress positional deviation on the outer circumference of the drum.

[Means for Solving the Problems] To achieve this object, the drum drive device of the present invention has the following features:
The number of teeth of the reduction gear is set so that the frequency of tooth contact of the reduction gear is equal to or higher than the frequency of rotation of the drum drive motor.

[Function] At the motor rotation frequency, uneven rotation is unavoidable due to eccentricity of the rotor inside the motor, cogging, etc.
In the drum drive motor used for normal drum drive devices,
The rotational frequency of the motor is set high enough that positional deviations on the outer periphery of the drum due to uneven rotation of the motor do not affect the copied image.

If the deceleration mechanism of the drum drive device is a one-stage reduction gear, the tooth contact frequency of the gear will not fall below the motor rotation frequency, but if two or three stages of deceleration are performed, the second stage Since the third stage gear rotates at a low speed, the frequency at which the teeth contact the gear is lower than the motor rotation frequency in a gear with a small number of teeth, causing a problem of positional deviation on the outer periphery of the drum.

The drum drive device of the present invention has the above-described configuration, and the positional deviation on the outer periphery of the drum due to the impact when the teeth of the gears come into contact can be made small to the extent that it does not affect the copied image.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

First, with reference to FIG. 1, the configuration of the drum drive device of this embodiment will be explained. The drum 10 is rotatably supported by a bearing 12. A gear 44 is attached to the shaft 14 of the drum 10 and is meshed with the gear 42. The gear 42 is fixed to the shaft 40 so as to rotate together with the gear 34, and the gear 34 is meshed with the gear 32 attached to the shaft 30 of the drum drive motor 20.

Next, the operation of the drum drive device of this embodiment will be explained. The drum drive motor 20 is controlled to rotate at a constant speed by a motor control means (not shown).

The drum drive motor 20 rotates through gear 32 and gear 3.
4. Gear 42. The speed is reduced by the gear 44 and transmitted to the drum 10, and the drum 10 rotates at a constant speed. gear 32
．． Gear 34. Gear 42. The number of teeth of the gear 44 is Z1, respectively.
+ Z2+ z3+ z4, and the motor shaft 30. Intermediate shaft 40. The number of rotations of the drum shaft 14 is nl (rpm) I n2 (r
pm) I n3 (r pm), then Z+
: Z2 −n2 : n1Z3 : Z
The relationship l −n3:n2 holds true.

In the first stage of deceleration, the tooth contact frequency of the gear is Zl nl
/6O-z2 n2 /60 (Hz), which is the rotational frequency of the drum drive motor 20 nt/60 (Hz).
) will never be smaller.

Similarly, in the second stage of deceleration, the frequency per tooth of the gear is Z3 n2 /60 = za n3 /60 (Hz), and taking the ratio with the motor rotation frequency nl /60 (Hz), z3n2 /nl − It becomes z3Zl /Z2.

In the case of z3z, /z2<1, as shown in Fig. 3(a), the drum rotation speed unevenness occurs at low frequencies due to the impact when the gear teeth contact. In the drive device, the number of gear teeth was set so that Z3 Zl /z2 >1, so the number of teeth in the gear was set as shown in Fig. 3(b).
As shown in , it occurs at a higher frequency than the motor rotation frequency. Therefore, the positional deviation on the outer periphery of the drum due to tooth contact of the gear becomes extremely small.

The present invention is not limited to the embodiments detailed above, and various changes can be made without departing from the spirit thereof. For example, in this embodiment, deceleration is performed using a two-stage reduction gear, but it is more effective to perform multi-stage deceleration of three or more stages.

[Effects of the Invention] As is clear from the detailed description above, the drum drive device of the present invention is configured such that the frequency of the tooth contact of the reduction gear is equal to or higher than the frequency of rotation of the drum drive motor. Since the number of teeth is set, there is an effect that positional deviation on the outer circumference of the drum can be suppressed to a small value.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the configuration of an embodiment of the present invention, Fig. 2 is a partially cutaway view of a copy sample for explaining the problems of a conventional drum drive device, and Fig. 3 is a frequency at which speed unevenness occurs. FIG. In the figure, 10 is a drum, 20 is a drum drive motor, 32.
34.42.44 is a reduction gear.

Claims (1)

[Scope of Claims] 1. A photosensitive paper transport drum or a photosensitive drum, a drum drive motor for rotating the drum, a motor control means for controlling the rotation of the drum drive motor, and a motor control means for controlling the rotation of the drum drive motor. and a gear that transmits data to the drum, the number of teeth of the reduction gear being set so that the frequency of tooth contact of the reduction gear is equal to or higher than the frequency of rotation of the drum drive motor. A drum drive device featuring: