JPS6340180A - Image forming device - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Object of the Invention [Field of Industrial Application] The present invention relates to an image forming apparatus such as an electrophotographic type or an electrostatic recording type.

[Conventional technology]

Conventionally, this type of device has a drive source that rotates (or rotates, the same applies hereinafter) an image carrier such as a photosensitive drum (or belt) or a dielectric drum (or belt), and a drive source that supplies paper to the image carrier. A single DC brush motor or DC brushless motor (hereinafter referred to as DC motor) is commonly used as a drive source for the paper feeding mechanism.

[Problem that the invention seeks to solve]

However, when such a DC motor rotates at a low speed of several torpm, the rotation becomes unstable.
It was necessary to rotate at a high speed of about ffi and to slow down the rotation using a gear to drive the image carrier and paper feeding mechanism. Furthermore, in order to rotate the DC motor with high precision, it is necessary to provide the motor with rotation detection means such as a frequency generator and to perform phase control.

In particular, devices such as laser printers, which record by scanning the surface of the image carrier with a beam, require strict rotational precision of the image carrier, which requires ingenuity in the means of controlling the rotation of the DC motor that is the drive source. .

Therefore, an image forming apparatus that uses a DC motor as a drive source to drive an image carrier and a paper feeding mechanism inevitably uses a gear head and frequency sporadic T%ill! This meant that the entire device was quite expensive.

Therefore, the present applicant previously proposed the use of a pulse motor in place of the DC motor. The speed of a pulse motor can be controlled by the input pulse rate, and it rotates smoothly and stably when rotated in or near the through range. In addition, since it rotates stably at low speed, the cost of the remoter can be reduced as it does not require a gear head or frequency generator.

However, pulse motors have the disadvantage of being taxed if there is a large load change. When the motor steps out, it remains stopped until it is restarted. Such load fluctuations are particularly likely to occur when the paper feeding roller of the paper feeding mechanism rotates.In order to strictly prevent step-out during feeding, it is necessary to use a pulse motor with sufficiently large torque. Admitted.

A motor with a large torque has a considerably large size and is also expensive.

The present invention has been proposed in view of the above, and it is possible to drive both the image carrier and the paper feeding mechanism with high precision and always stably without causing step-out phenomena. Moreover, it is an object of the present invention to provide a drive system that is devised so that the construction cost of the drive system can be reduced.

Structure of the Invention (Means for Solving Point +iiia) The present invention uses a pulse motor as a drive source for rotating or rotationally driving an image bearing member, and a DC motor as a drive source for a paper feeding mechanism. This article summarizes an image forming apparatus characterized by the following.

[For production]

That is, by configuring the image carrier and the paper feeding mechanism to be driven by respective drive sources, load fluctuations during paper feeding are not applied to the drive source of the image carrier, so that the drive source of the image carrier is As a result, there is no need to worry about tax adjustment even if a small-sized napulse motor (including a synchronous motor) having a relatively small torque is used, and the cost of the motor as a drive source for the image carrier can be reduced. It is also possible to ensure highly accurate and stable driving of the image carrier.

By using a DC motor as the drive source for the paper feeding mechanism,
There is no need to worry about step-out due to large load fluctuations during paper feeding. Furthermore, since the motor does not need to be rotated or controlled with high precision, even if a DC motor is used, there is no need to perform costly phase control, and the cost of the control circuit can be reduced.

〔Example〕

The figure shows one embodiment, and the device in this embodiment is a laser beam printer.

Reference numeral 1 denotes an electrophotographic photosensitive drum (hereinafter referred to as drum) as an image carrier, which is freely rotatable about an axis 1a.

2 is a pulse motor (or synchronous motor) as a rotational drive source for the drum l, 3 is a motor gear integrated with the final shaft 2a on the motor side, and the gear is connected concentrically to the rear end of the drum l. It meshes with a drum gear (not shown) provided integrally with the. The tram 1 receives the driving force of the motor 2 via the gear 3 and drum gear, and is rotated in the direction of the arrow at a predetermined circumferential speed around the shaft 1a.

The drum 1 receives a uniform positive or negative charge on its peripheral surface by the charger 4 during its rotation.

Next, in the exposure section 5, the target image is subjected to laser beam scanning exposure by the laser beam scanning section 6, so that a static image M and a latent image of the target image are formed on the peripheral surface thereof.

The laser beam scanning section 6 includes a semiconductor laser (not shown), a rotating polygon mirror 61, an f-theta lens 62, a reflecting mirror 63, etc.
On the other hand, a laser beam modulated in accordance with the time-series electric pixel signals of the target image is output, and the drum 1 is exposed in the main scanning direction in the direction of the drum generatrix.

The electrostatic latent image formed on the surface of the drum 1 is developed with toner by a developing device 7, and reaches the position of a transfer discharge device 8. The toner developed image is then sequentially transferred from the paper feeding mechanism section 9 to the two surfaces of the transfer paper fed between the drum l and the transfer discharger 8 in synchronization with the rotation of the drum l.

The transfer paper on which the toner image has been transferred is sequentially separated from one surface of the drum by a separating member (not shown), and then sent to the fixing device 1 via the guide 10.
1, undergoes image fixation, and is discharged as an image-formed product onto a paper discharge tray portion 12.

The surface of the drum from which the transfer paper has been separated is made into a clean surface by a glue leaning section (not shown), and is subjected to repeated image formation.

The paper feed mechanism 9 is a paper feeder 7) 9 in which paper p is loaded and stored.
1. It consists of a half-moon-shaped (broken circle) paper feed roller 92, a registration roller 93, etc. 94 is a DC motor as a drive source of the paper feeding mechanism 9, and 95 is a final shaft 94 on the motor side.
A is a motor gear integrated with the paper feed roller 92.
It meshes with a roller gear (not shown) provided integrally with the shaft. The paper feed roller 92 transfers the driving force of the motor 94 to a clutch (
(not shown) - The gear 95 receives one revolution in the paper feed direction at each predetermined paper feeding timing through the roller gear, and is intermittently rotated by a predetermined number of rotations, and the paper p in the cassette 91 is The sheets are sent out toward the registration rollers 93 one by one.

The leading edge of the paper p sent out from the cassette 91 by the paper feed roller 92 into the nip portion of the registration roller 93, which is stopped at that time, is synchronized with the rotation of the drum 1. The recording material is fed toward the transfer unit 8 by the registration rollers 93 which are rotationally driven at a predetermined timing.

The fixing roller of the fixing device 11 may be driven by transmitting the rotational force of the drum drive motor 2 via a transmission mechanism, and the registration roller 93 may be driven by the rotational force of the drum drive motor 2 or paper feed motor 94. The power may be transmitted and driven via a clutch.

C. Effects of the Invention As described above, in the image forming apparatus, the image bearing member and the paper feeding mechanism are driven by separate drive sources, and the former drive source is a pulse motor (a synchronous motor may also be used). By using a DC motor as the drive source for the latter, it is possible to drive both the image carrier and the paper feeding mechanism with high precision and always stably without causing tax adjustment phenomena. Moreover, the construction cost of the drive system can be reduced, and the intended purpose can be well achieved.

[Brief explanation of drawings]

The figure is a schematic configuration diagram of a laser beam printer as an example. 1 is a photosensitive drum as an image carrier; 2 is a pulse motor as a rotational drive source for the drum; 92 is a paper feed roller; 94
is a DC motor as a rotational drive source for the roller.

Claims (1)

[Claims] (1) An image forming apparatus characterized in that a pulse motor is used as a drive source for rotating or rotationally driving an image carrier, and a DC motor is used as a drive source for a paper feeding mechanism.