Murata Kikai Kabushiki Kaisha

Murata Machinery, Ltd.

Takahiro Sasai

Akinori Nishida

Yuji Suzuki

Shu Ikezaki

Tadahiro Yokogawa

Akinori Nishizawa

Yoshitaka Taruno

When printing, an image forming apparatus determines, based on a threshold voltage corresponding to a print speed during printing, whether or not a corona wire of a charger needs to be cleaned. On the basis of whether or not a monitoring voltage corresponding to a current value of a charged bias, which is applied to the corona wire by a charged-bias high-voltage power supply, is equal to or more than a predetermined threshold voltage corresponding to the print speed during printing, the image forming apparatus determines whether or not the corona wire needs to be cleaned.

Image forming apparatus and image forming method

An image forming apparatus that prevents transfer defects such as the occurrence of white spots includes a photoreceptor drum, a transfer roller, a transfer bias application circuit that applies a transfer bias to the transfer roller, a static elimination needle that eliminates static of a recording paper, a static elimination bias application circuit that applies a static elimination bias to the static elimination needle, and a printer controller. The printer controller controls the static elimination bias application circuit so that a potential difference between the static elimination needle and the recording paper during the period from when a front end region of the recording paper passes by the static elimination needle until when a front end of the recording paper comes into contact with a conveyance guide becomes smaller than the potential difference during the period that the front end region of the recording paper passes by the static elimination needle.

Image forming apparatus with static elimination

A control device executes toner concentration control that controls an operation of a developing device such that a value of detection output detected by a concentration detecting device falls within a predetermined range. Moreover, when controlling drive of a first driving device, which drives at least an image carrier, and drive of a second driving device, which drives at least a fuser device, the control device executes operation control that starts the drive of the first driving device before the drive of the second driving device.

Image forming device

An image forming device includes a photoconductive drum, a discharge electrode which discharges corona onto a surface of the photoconductive drum, and a cleaning member which cleans the discharge electrode by moving on the discharge electrode. The image forming device further includes a detection device, which is arranged on one of a first side and a second side in a moving direction of the cleaning member, and detects a current value of an electric current discharged from the discharge electrode.

Image forming device including a cleaning member

An image forming device includes a motor, a photoconductive drum, a charging unit, an abrasion tool, a timer, and a controller. The charging unit is provided at a periphery of the photoconductive drum, and charges the photoconductive drum by a corona discharge method. The abrasion tool is provided at the periphery of the photoconductive drum, and abrades the surface of the photoconductive drum while the photoconductive drum is rotating. The timer measures a job interval from when the motor is stopped to end a previous print job until when the motor is driven to start a next print job. The controller executes over a predetermined period of time a pre-rotation process to adjust the photoconductive drum and a peripheral system of the photoconductive drum into an optimum state, and calculates a period when the pre-rotation process is to be executed according to the measured job interval.

Image forming device having variable pre-rotation cleaning process

An image forming device includes an image forming unit that includes an image carrier which carries an electrostatic latent image, a developing unit which forms a developing nip by contacting with the image carrier and develops the latent image by using toner, a transfer unit which forms a transferring nip by contacting with the image carrier and transfers a toner image onto a recording paper, and a first driving unit which rotates the image carrier, the developing unit and the transfer unit. The image forming device also includes a laser scanner unit that includes a polygon mirror and a second driving unit which rotates the polygon mirror. In addition, the image forming device includes a first control unit that starts driving of the second driving unit at a same time as a start of driving of the first driving unit, and a second control unit that executes a cleaning sequence process to return toner adhered on the transfer unit back to the image carrier during a period from the start of the driving of the second driving unit until a print permitting signal is output by the laser scanner unit.

Image forming device with cleaning sequence process for returning toner adhered on transfer roller back to photoconductive drum

A cleaner-less image former that can prevent cleaning efficiency from reducing and maintain high print quality. After a printing process is started, one lookup table LUT is selected from a group of LUTs based on a temperature detected by a temperature sensor and the number of sheets of paper which have been printed. A pre-transfer bias is determined by applying a current value memorized in a feedback current value memorizing part to the selected LUT, the determined pre-transfer bias is applied to a transfer roller, and then a transfer bias is determined based on the above current value and the temperature. The determined transfer bias is applied to the transfer roller. The residual toner remaining on the transfer roller, a charge brush and a memory removal brush is removed by applying the pre-transfer bias.

Image forming apparatus with controller that applies preliminary transfer bias to transfer member based on print workload

An image forming device includes an image forming unit that includes a photoconductive drum which carries an electrostatic latent image, a developing roller which forms a developing nip by contacting the photoconductive drum and develops the latent image by using toner, and a transfer roller that forms a transferring nip by contacting the photoconductive drum and transfers a toner image onto a recording paper. A transferring voltage impressing circuit impresses to the transfer roller, a voltage of an opposite polarity to a polarity of a transfer process, for a prescribed period of time during a period when the recording paper is absent in the transferring nip. A developing voltage impressing circuit impresses to the developing roller, a voltage of a same polarity as a developing process and lower than the developing process when a field impressed with the voltage of the opposite polarity by the transferring voltage impressing circuit passes the developing nip.

An electrophotographic image forming apparatus and method of controlling the apparatus during a warm-up operation. During the warm-up operation, a heating unit for heating a fuser will be turned on and a motor for starting rotation of a photosensitive body will be activated when the temperature of the fuser reaches a motor rotation start temperature. When the temperature of the fuser reaches a warm-up completion temperature, the warm-up operation will be stopped and the rotation of the photosensitive body will be terminated. The warm-up completion temperature is higher than a stand-by temperature but lower than a fusing temperature.

Image forming apparatus and warm-up method

A facsimile machine performs a printing operation in an optimum environment by detecting the environment of the facsimile machine when it receives a facsimile signal from a remote device. A control circuit assembly ( ) of the facsimile machine includes a scanner unit ( ), a printing unit ( ) and a transmission and reception unit ( ). All of them are operated by commands from a main controller ( ). A memory ( ) that accumulates image information is associated with the main controller ( ). If the image information is input into the transmission and reception unit ( ), a fan ( ) and a heater ( ) are operated in accordance with control information stored in a table ( ) prepared in the memory ( ) until attainment of the operation-assured environment. After that, the printing unit ( ) prints the information on sheets of paper. By pressing a button ( ), the printing is forcibly output at whatever time.

Image forming apparatus for operating under the optimum environment condition

In an image forming machine ( ), a toner image formed on a photosensitive drum ( ) is transferred to a recording sheet by applying a voltage (transfer voltage) to a transfer roller ( ). The value of the voltage to be applied is determined by performing a feed back sequence based on information obtained after a predetermined number of recording sheets have been recorded. The point when a current detected in connection with the applied voltage has reached a predetermined value (&agr;) is considered the saturation of the applied voltage. Once this point is reached, there will be no feed back sequences to be performed. After the application voltage saturation, therefore, it is possible to continue the printing operation without any interruption since no feed back sequence is performed. This shortens a job duration.

Image forming apparatus and image forming method employing the same

A predetermined level of voltage is applied to a transfer roller ( ) to transfer a toner image on a photosensitive drum ( ). After a predetermined number of recording sheets are made, a cleaning sequence is started wherein a voltage of &minus;900V is applied as a cleaning voltage. Before applying the transfer voltage of 3 kV, intermediate voltage is applied once or more under the control of a control unit ( ). The control unit ( ) instructs the application of the voltage through an electrical circuit ( ) to the transfer roller ( ) based on conditions set in a memory ( ) and/or information given by a machine temperature sensor ( ).

A warm-up completion temperature (temp,) of an electro-photographic type printer is set to be lower than a stand-by temperature (temp,). When a temperature detector detects that a temperature of a fuser reaches the warm-up completion temperature, then a controller ends the warm-up operation. The warm-up time between the turning on of power and the completion of the machine's warm-up operation is thus reduced. An amount of power required for the warm-up operation is also reduced.

Image forming apparatus and warming up method

A toner image formed on the photosensitive body (21) is transferred to printing paper by applying a voltage from a transfer roller (25) in an image transfer section of an image forming device (1). The transfer roller (25) is provided with a transfer voltage generating circuit (31) connected to a control unit (30). Information about an optimum transfer voltage is gathered from a look-up table (34) provided in a memory (33), in accordance with environmental conditions such as temperature and humidity in the device (1) which are detected by a sensor (35). The voltage to be applied to the transfer roller (25) is determined by the control unit (30). The voltage applied to the transfer roller between sheets of printing paper is also changed in accordance with the detected environmental conditions.

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Kyoto, Japan

Takahiro Sasai