Electrophotography – Image formation – Photoconductive member
Reexamination Certificate
2000-01-19
2001-09-04
Chen, Sophia S. (Department: 2852)
Electrophotography
Image formation
Photoconductive member
C399S075000
Reexamination Certificate
active
06285847
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a printer for forming a toner image to be transferred onto a work piece.
In a prior art printer, a latent image roller adapted to be electrified in such a manner that an electrostatic latent image is formed thereon transmits a torque from a motor to an image developing roller for holding thereon toner to be supplied onto the latent image roller so that the electrostatic latent image is developed by the toner to form a toner image.
OBJECT AND SUMMARY OF THE INVENTION
An object of the present invention is to provide a printer in which a position and shape of a latent image roller is correctly kept, and/or a rotational movement of the latent image roller is correctly controlled.
In a printer for forming a toner image to be transferred onto a work piece, comprising, a latent image roller including an outer peripheral image surface adapted to be electrified in such a manner that an electrostatic latent image is formed thereon, an image developing roller including an outer peripheral toner surface adapted to hold thereon toner to be supplied onto the outer peripheral image surface so that the electrostatic latent image is developed by the toner to form the toner image, an electrifier for electrifying the outer peripheral image surface, and a discharger for electrically discharging partially the electrified outer peripheral image surface to form the electrostatic latent image, it is preferable that a motor drives both the latent image roller and the image developing roller.
If the image developing roller is prevented from being driven through the latent image roller by the motor, a driving force for driving the image developing roller does not affect a position of the latent image roller, a shape deformation of the latent image roller and a rotational movement of the latent image roller. If the printer comprises an intermediate rotational member connected to the motor to be rotationally driven by the motor and including a rotational part mechanically connected to the image developing roller to drive the image developing roller and another rotational part mechanically connected to the latent image roller to drive the latent image roller so that an output torque of the motor is divided at the intermediate rotational member into a first part torque to be supplied to the image developing roller and a second part torque to be supplied to the latent image roller, the driving force of the first part torque for driving the image developing roller is not supplied to the latent image roller, so that the shape, position and rotational movement of the latent image roller can be correctly or desirably kept.
If a first teethed pulley is connected to the motor to be driven by the motor, a second teethed pulley is connected to the latent image roller to drive the latent image roller, a teethed belt includes teeth for engaging both the first and second teethed pulleys to drive the latent image roller by the motor, and the teeth of the belt is formed of an elastomer, the rotational movement of the latent driven by the motor through the elastomer teeth belt is kept smooth or constant by a large-area and low-rigidity engagement between the elastomer teeth belt and the teethed pulleys for compensating errors in shape and positional relationship of a force transmission mechanism for the latent image roller. It is desirable that the image developing roller is prevented from being driven through the teethed belt for driving the latent image roller. It is desirable that the image developing roller is prevented from being mechanically connected through the latent image roller to the motor. It is desirable that the image developing roller is prevented from being mechanically connected through the teethed belt to the motor.
If the intermediate rotational member connected to the motor to be rotationally driven by the motor includes a first teethed pulley and another rotational part mechanically connected to the image developing roller to drive the image developing roller so that an output torque of the motor is divided at the intermediate rotational member into a first part torque to be supplied to the first teethed pulley and a second part torque to be supplied to the image developing roller through the another rotational part, a second teethed pulley connected to the latent image roller to drive rotationally the latent image roller, and a teethed belt including teeth engages both the first and second teethed pulleys to drive rotationally the latent image roller by the first part torque while the second part torque is prevented from being transmitted by the teethed belt, and the teeth of the belt is formed of an elastomer, the smooth and constant rotational movement of the latent image roller obtained by being driven through the elastomer teeth belt is not affected by the second part torque for the image developing roller. That is, it is preferable that the image developing roller is prevented from being driven through the teethed belt for driving the latent image roller.
If the image developing roller is driven through an Oldham's coupling by the motor, the Oldham's coupling absorbs errors in position and attitude of the image developing roller so that a positional relationship between the image developing roller and the latent image roller facing to each other is not affected by an undesirable stress for absorbing the errors in position and attitude of the image developing roller.
If a coupling pair of a first coupling part including at least one pair of radially outer (inner peripheral) teeth (arranged on an inner periphery of the part), and a second coupling part including at least one pair of radially inner (outer peripheral) teeth (arranged on an outer periphery of the part) is arranged between the motor and the latent image roller to transmit a driving force from the motor to the latent image roller, one of the first and second coupling parts is mechanically connected to the motor, another of the first and second coupling parts is mechanically connected to the latent image roller, and the radially outer teeth and the radially inner teeth face to each other radially and circumferentially and engage each other to transmit a part of torque generated by the motor to the latent image roller, an engaging area and a mutual engaging number of the radially inner and outer teeth are increased in comparison with those obtained by a mutual engage between outer peripheral teeth gears whose teeth are arranged on an outer periphery of the gears so that the rotational movement of the latent driven by the motor through the coupling pair as limited above is kept smooth or constant. The radially outer teeth and the radially inner teeth extend axially and radially to face to each other circumferentially.
If the radially outer teeth and the radially inner teeth are involute teeth respectively, the rotational movement of the latent driven by the motor through the coupling pair is not affected by a positional relationship between the first and second coupling parts or a distance between rotational axes of the first and second coupling parts.
If the radially outer teeth substantially are opposite radially to each other relative to a rotational axis of the coupling pair, and the radially inner teeth substantially are opposite radially to each other relative to the rotational axis of the coupling pair so that the radially inner and radially outer teeth engage each other at both radial sides opposite to each other relative to the rotational axis of the coupling pair to restrain an engagement between the radially inner and outer teeth from generating a radial force to be applied to the latent image roller when transmitting the part of torque to the latent image roller through the engagement therebetween or the radial forces generated respectively at the radial sides opposite to each other relative to the rotational axis of the coupling pair balance each other, the latent image roller is not deformed by the radial force generated by the
Ijima Yoshiaki
Kawano Yuzo
Tajima Kazuhiko
Tanizaki Jun-ichi
Chen Sophia S.
Matsushita Electric - Industrial Co., Ltd.
Stevens Davis Miller & Mosher LLP
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