Abstract: A stepping motor control device includes a driving IC driving a stepping motor by PWM control, and a setting circuit for setting PWM frequency of the driving IC. The setting circuit sets the driving IC such that in stepping motor accelerating and decelerating periods, the PWM frequency of the driving IC becomes higher than the PWM frequency of the driving IC in a constant-speed period of the stepping motor. Thus, power loss of the driving IC in the stepping motor accelerating and decelerating periods can be reduced, and ripple current can be reduced.

Abstract: A stepping motor control device includes a driving IC driving a stepping motor by PWM control, and a setting circuit for setting PWM frequency of the driving IC. The setting circuit sets the driving IC such that in stepping motor accelerating and decelerating periods, the PWM frequency of the driving IC becomes higher than the PWM frequency of the driving IC in a constant-speed period of the stepping motor. Thus, power loss of the driving IC in the stepping motor accelerating and decelerating periods can be reduced, and ripple current can be reduced.

Abstract: A stepping motor control device includes a driving IC driving a stepping motor by PWM control, and a setting circuit for setting PWM frequency of the driving IC. The setting circuit sets the driving IC such that in stepping motor accelerating and decelerating periods, the PWM frequency of the driving IC becomes higher than the PWM frequency of the driving IC in a constant-speed period of the stepping motor. Thus, power loss of the driving IC in the stepping motor accelerating and decelerating periods can be reduced, and ripple current can be reduced.

Abstract: Adjustment of white balance based on a measurement result of light emission luminance of a backlight is allowed to be executed accurately and effectively. A backlight luminance detection portion detects light emission luminance of an LED backlight in a state where an optical shutter of a liquid crystal display panel is closed. A main control portion adjusts light emission luminance of the LED backlight according to light emission luminance detected by the backlight luminance detection portion. Here, the main control portion compares light emission luminance of LEDs of RGB detected by the backlight luminance detection portion with light emission luminance of RGB in white balance adjustment that is stored in advance in the storage portion, and adjusts, when an error occurs between the compared light emission luminance, the light emission luminance of each of the LEDs of RGB so as to eliminate the error.

Abstract: In an image forming apparatus, the number of components and a size of the apparatus is reduced by realizing both functions for detecting a toner patch image to perform image quality adjustment and for performing precise color adjustment depending on a sheet color with one color sensor. The color sensor is disposed in a vicinity of a transport belt, a reference toner image is formed on the transport belt at a predetermined timing. A color of the reference toner image formed on the belt is detected by the color sensor to adjust development conditions. Further, the sheet is transported in a state where the transport belt is separated from a photoreceptor drum, and the sheet color is detected by the color sensor, and thereafter the transport belt touches the photoreceptor drum to transport the sheet to a transfer portion.

Abstract: In a fixing apparatus that has a heating roller, and heats a sheet where an image by a developer has been transferred, to thereby fix the image on the sheet, the following are provided: a first sensor that detects the radiant heat from the heating roller; a second sensor that detects the ambient temperature of the first sensor; a computing circuit that computes a threshold value for determining whether the temperature of the heating roller is abnormal or not; and a controlling circuit that controls the operation condition of the heating roller based on output values of the first sensor and the second sensor and the threshold value computed by the computing circuit.

Abstract: There are provided a fixing device and an image forming apparatus capable of reducing a sensing error of a surface temperature of a heating roller. The fixing device includes a temperature sensor for sensing the surface temperature of the heating roller, and a temperature calculation circuit. The temperature calculation circuit includes a noise removal prevention circuit. The temperature sensor includes an infrared ray sensing thermistor and a compensation thermistor, and the noise removal prevention circuit prevents removal of a part of an AC component (such as a high frequency component in a noise) included in a difference between outputs (difference output) of the infrared ray sensing thermistor and the compensation thermistor. Thus, the AC component is prevented from being offset when the difference outputs are averaged, thus reducing the sensing error of the surface temperature of the heating roller based on the average value of the difference outputs.

Abstract: A fixing apparatus includes a heating roller having a heating unit and a press roller that is in contact with the heating roller. The fixing apparatus fixes an image of developer onto a sheet holding the image by heating and supporting the sheet. The fixing apparatus comprises a first sensor for detecting radiant heat from the heating roller, a second sensor for detecting the ambient temperature of the first sensor, a determination unit for determining whether the temperature of the heating roller is abnormal or not based on an output value of the first sensor and an output value of the second sensor, and a control unit for controlling an operating state of the heating unit based on the determination result.

Abstract: In an image forming apparatus, the number of components and a size of the apparatus is reduced by realizing both functions for detecting a toner patch image to perform image quality adjustment and for performing precise color adjustment depending on a sheet color with one color sensor. The color sensor is disposed in a vicinity of a transport belt, a reference toner image is formed on the transport belt at a predetermined timing. A color of the reference toner image formed on the belt is detected by the color sensor to adjust development conditions. Further, the sheet is transported in a state where the transport belt is separated from a photoreceptor drum, and the sheet color is detected by the color sensor, and thereafter the transport belt touches the photoreceptor drum to transport the sheet to a transfer portion.

Abstract: There are provided a fixing device and an image forming apparatus capable of reducing a sensing error of a surface temperature of a heating roller. The fixing device includes a temperature sensor for sensing the surface temperature of the heating roller, and a temperature calculation circuit. The temperature calculation circuit includes a noise removal prevention circuit. The temperature sensor includes an infrared ray sensing thermistor and a compensation thermistor, and the noise removal prevention circuit prevents removal of a part of an AC component (such as a high frequency component in a noise) included in a difference between outputs (difference output) of the infrared ray sensing thermistor and the compensation thermistor. Thus, the AC component is prevented from being offset when the difference outputs are averaged, thus reducing the sensing error of the surface temperature of the heating roller based on the average value of the difference outputs.

Abstract: In a fixing apparatus that has a heating roller, and heats a sheet where an image by a developer has been transferred, to thereby fix the image on the sheet, the following are provided: a first sensor that detects the radiant heat from the heating roller; a second sensor that detects the ambient temperature of the first sensor; a computing circuit that computes a threshold value for determining whether the temperature of the heating roller is abnormal or not; and a controlling circuit that controls the operation condition of the heating roller based on output values of the first sensor and the second sensor and the threshold value computed by the computing circuit.

Abstract: A fixing apparatus, which comprises a heating roller having a heating unit and a press roller that is in contact with the heating roller with pressure and fixes an image of developer onto a sheet holding the image by heating and supporting the sheet with the heating roller and the press roller, comprises a first sensor for detecting radiant heat from the heating roller, a second sensor for detecting the ambient temperature of the first sensor, a determination unit for determining whether the temperature of the heating roller is abnormal or not based on an output value of the first sensor and an output value of the second sensor, and a control unit for controlling an operating state of the heating unit based on determination result.

Abstract: A tandem-type image forming apparatus for forming a multi-color image on a sheet transported by an endless transfer/transport belt, by sequentially laying on the sheet images developed in respective image forming stations. The apparatus includes: transfer rollers, each in contact through the transfer/transport belt with an image carrier provided in each image forming station; and a voltage applying device for applying a non-transfer bias voltage to only the transfer rollers that are in contact with the image carriers when a transfer process is not performed, the non-transfer bias voltage having the same polarity as a transfer bias voltage and being lower than the transfer bias voltage.

Abstract: A tandem-type image forming apparatus for forming a multi-coor image on a sheet transported by an endless transfer/transport belt, by sequentially laying on the sheet images developed in respective image forming stations. The apparatus includes: transfer rollers, each in contact through the transfer/transport belt with an image carrier provided in each image forming station; and a voltage applying device for applying a non-transfer bias voltage to only the transfer rollers that are in contact with the image carriers when a transfer process is not performed, the non-transfer bias voltage having the same polarity as a transfer bias voltage and being lower than the transfer bias voltage.

Abstract: A control circuit for outputting a signal for controlling an amount of light emitted from a plurality of light emitting elements. The control circuit includes a controller or CPU, and a D/A converter outputting a signal for setting a voltage in multiple gradation in accordance with a lighting state of the light emitting element. An amplifying circuit amplifies an output of the D/A converter and outputs an amplified output as a control signal. A reference voltage generating circuit generates a reference voltage and a comparator compares the control signal with the reference voltage. The controller varies an output of the D/A converter based on the result of comparison by the comparator, to adjust the output of the D/A converter so that the control signal is equivalent to the reference voltage. Accordingly each voltage is reset in the multiple gradation to allow the light emitting element to appropriately emit light based on the adjusted output.

Abstract: An image-forming apparatus which controls the temperature of the contained thermal fixing device on standby, based on the image formation history information on times of past image formations, etc., to efficiently reduce the power consumption during standby without lowering the availability factor of the image-forming apparatus, which is constructed so that the data on use frequency, including the current time, the number of copies made, etc., (image formation history information) is stored each time an image-forming process is executed, the control section sums the image formation history information on an hourly or other basis, and the temperature of the thermal fixing device on standby is controlled based on the current time-related image formation history information summed on an hourly basis.

Abstract: An image-quality stabilizer provided in a copying machine executes a feedback control on a charger output based on an adhering toner amount detected by a patch sensor in a pre-rotation of the photoreceptor drum directly before each copying operation is started. A time interval between feedback controls is counted by a timer, and a CPU sets an appropriate time interval in accordance with an amount of change in the adhering toner amount detected by the patch sensor or in accordance with the charger output before and after feedback control. According to the described arrangement, since the feedback control is executed at a timing set in accordance with the amount of change in adhering toner, variations in image quality such as an increase in image density caused by overcompensation and an excessive feedback control can be prevented, thereby ensuring stable image quality by efficiently compensating the image density without increasing an amount of toner consumption.

Abstract: A liquid crystal driving system using a dynamic driving method, which includes circuits for driving liquid crystals by applying AC-converted signals containing a specific frequency which is higher than the frame-frequency and different from the duty factor of the data signals.

Abstract: An arrangement of a liquid crystal display unit includes a display panel having a plurality of terminals, a plurality of flexible films made of electrically nonconductive material and an LSI chip bonded into each flexible film. A plurality of electrodes are deposited on each film, with the films being provided in association with the display panel to electrically connect each LSI chip with the display panel terminals.