Murata Kikai Kabushiki Kaisha

Makoto Tanaka

Takashi Nakao

Naritoshi Takamatsu

An overhead bufferis provided on a side of a running railfor an overhead travelling carriage. The height level of an article on the overhead bufferis slightly lower than that on the running overhead travelling carriage. This height is at least such that the overhead bufferdoes not interfere with an operator. According to the present invention, the overhead buffer can be installed even if load ports are consecutively provided.

Overhead travelling carriage system

An image forming machine provided with an image recording unit, a reading unit on the image recording unit, and a platen cover. The reading unit and the platen cover can be opened and closed. The image forming machine includes a first lock unit for enabling the platen cover to be locked to the reading unit, with the platen cover closed, and a second lock unit for interlocking with the first lock unit and releasing connection between the reading unit and the image recording unit. When the reading unit is opened upwards relative to the image recording unit to exchange a process unit of the image recording unit or eliminate jam in the image recording unit, only in the state where the platen cover is locked to the reading unit, the reading unit can be opened upwards.

Image forming apparatus, including a lock unit for preventing a reading unit and a platen cover from being opened simultaneously

A drive power transmission system located between a paper feed roller and a motor for transmitting a drive power to the paper feed roller from the motor only when a load acting on the paper feed roller in a direction opposite a rotating direction of the paper feed roller is smaller than a certain amount. The drive power transmission system is incorporated in an image processing device such as a facsimile machine. The paper feed roller and other rollers such as separation roller and retard roller cooperate to feed a sheet of paper from a stack of paper on a paper tray one sheet at a time. Eventually all the sheets are picked up from the paper tray and the paper feed roller directly contacts the paper tray. In this case, an excessively large shock or load acts on the paper feed roller and various associated parts which are provided to drive the paper feed roller such as a gear train mechanism. The drive power transmission system includes a coil spring which is unwound to disconnect the motor from the paper feed roller so as not to transmit the drive power to the paper feed roller when such a large load is exerted on the paper feed roller.

Drive power transmission

A device for outputting a suitable rotation torque relative to a load torque or actual torque exerted on a stepper-motor when the stepper-motor is used as a drive of an image processing device. The output torque of the stepper-motor depends on a supply current to the stepper-motor. CPU determines a suitable supply current using a table in ROM so that the stepper-motor is able to rotate at an optimum rotation torque. To this end, CPU sends a particular signal to the motor driver so that an appropriate supply current is supplied to the excitation phases A/B of the stepper-motor. The CPU determines the load torque based on an integrated current fed to the stepper-motor during a particular period. The CPU calculates difference between the load torque and rotation torque and determines the signal to be applied to the motor driver based on the torque difference.

Stepper-motor control method

A sheet feeding arrangement has a main body and a width direction. A sheet passage extends in a main body of the arrangement like a letter 'U' in a direction perpendicular to the width direction of the arrangement. The 'U' of the passage has a predetermined width in the width direction of the arrangement. A sheet feeding shaft is supported inside the 'U' of the sheet passage and extends in the width direction of the arrangement. The sheet feeding shaft has a drive roller fixedly mounted thereon. The drive roller partly extends into the sheet passage to be able to contact a sheet in the sheet passage. A motor is connected with the sheet feeding shaft for driving the shaft to feed the sheet by the drive roller. A speed reduction mechanism is provided between the motor and the sheet feeding shaft to transmit drive power from the motor to the shaft with a reduced speed. The sheet feeding shaft and the speed reduction mechanism are united with the motor to form a sheet feeding unit, and the sheet feeding unit is confined inside the 'U' of the sheet passage. The sheet feeding unit can be designed to be compact in the width direction of the sheet feeding arrangement so that an overall dimension of the sheet feeding arrangement can also be reduced.

Sheet feeding apparatus

A sheet feeding mechanism has a pick up roller which picks up one sheet from a pile on a tray and sends It to contact between a separation roller and a retardation roller. A shaft which positively rotates in a sheet feeding direction is provided with a first gear and the separation roller via an arm pivotable about the shaft and a spring clutch. The arm carries a second gear which receives rotary power from the first gear, a third gear engaged with the second gear and the pick up roller connected with the third gear. The arm is biased upwardly and a negative torque is applied to the second or third gear. Below the separation roller, provided is the retardation roller which is mounted on another shaft via a torque limiter and pressed against the separation roller. The another shaft rotates in a direction opposite the sheet feeding direction. Up and down movement of the pick up roller is mechanically controlled.

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Nagaokakyo, Japan

Makoto Tanaka