Abstract: A fan motor speed control circuit includes: a driving circuit configured to drive a fan motor so as to run at a rotation speed corresponding to a drive signal; a comparison circuit configured to output a comparison signal for matching a rotation speed of the fan motor with a target rotation speed, based on a reference signal corresponding to the target rotation speed of the fan motor and a speed signal corresponding to the rotation speed of the fan motor; and a selection circuit configured to output to the driving circuit the drive signal corresponding to one signal out of the reference signal and the comparison signal, the one signal being a signal by which the fan motor is driven at a higher rotation speed.

Abstract: A motor speed control circuit includes: a voltage generating circuit configured to output a reference voltage corresponding to a target rotation speed of a motor and a speed voltage corresponding to a rotation speed of the motor, and change either the reference voltage or the speed voltage according to a temperature; a comparison circuit configured to compare the speed voltage with the reference voltage; and a driving circuit configured to drive the motor so as to match a level of the speed voltage to a level of the reference voltage, based on a comparison result from the comparison circuit.

Abstract: A motor speed control circuit which controls a rotational speed of a motor by controlling an amount of current flowing through a drive coil of the motor. The control circuit comprises a reference voltage circuit that generates a reference voltage corresponding to a speed-specifying signal inputted to specify the rotational speed of the motor; a clamp circuit that limits a level of the reference voltage generated by the reference voltage circuit; a comparator that has a speed voltage corresponding to an actual rotational speed of the motor and the reference voltage limited in level by the clamp circuit applied thereto and compares the two; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

Abstract: An image forming apparatus comprises: a reader to read image; an output part to output the image; an information giving part to give additional information to the image before the image is outputted by said output part; an output controller to make said output part output a plurality of test patterns for output level correction of additional information in different output levels; a data calculator for output level correction, to calculate data for output level correction of said additional information based on reading results drew by said reader from said outputted test patterns for output level correction of additional information; and an output level corrector to correct an output level of said additional information based on said calculated data for correction.

Abstract: An image forming device for forming an image on an image carrier using a different grayscale reproduction method for each of two or more different attributes contained in portions of the image. The image forming device forms a different standard pattern in one-to-one correspondence with each different attribute contained in the image portions, using a grayscale reproduction method used for reproducing image portions containing the attribute, detects density of each standard pattern formed by the standard pattern forming unit, sets, for each different attribute, a condition for correcting grayscale of the image portions containing the attribute, in accordance with the detected density, and corrects grayscale of the image portions in accordance with each condition set by the correction condition setting unit.

Abstract: A motor speed control integrated circuit which controls a rotational speed of a motor by controlling the amount of current flowing through a drive coil of the motor. The integrated circuit comprises a first input terminal to have an analog speed-specifying signal in analog amount specifying the rotational speed of the motor input thereto; a second input terminal to have a digital speed-specifying signal in digital amount specifying the rotational speed of the motor input thereto; a reference voltage circuit that generates a reference voltage corresponding to the analog speed-specifying signal and/or the digital speed-specifying signal; a comparator that compares a speed voltage corresponding to the actual rotational speed of the motor and the reference voltage; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

Abstract: An image forming apparatus of the invention includes an image carrier, an exposure device performing exposure for forming a toner image on a surface of the image carrier and having at least a first exposure light source and a second exposure light sources a sensor for detecting specified patterns, which are formed on the image carrier at a specified time with use of the first and second exposure light sources, a storing unit for storing a correlation, which is attained from a detection result by the sensor, between the first and second exposure light sources, and a controller for controlling the first and second exposure light sources based on the correlation.

Abstract: A motor speed control circuit which controls a rotational speed of a motor by controlling an amount of current flowing through a drive coil of the motor. The control circuit comprises a reference voltage circuit that generates a reference voltage corresponding to a speed-specifying signal inputted to specify the rotational speed of the motor; a clamp circuit that limits a level of the reference voltage generated by the reference voltage circuit; a comparator that has a speed voltage corresponding to an actual rotational speed of the motor and the reference voltage limited in level by the clamp circuit applied thereto and compares the two; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

Abstract: A motor speed control circuit which controls a rotational speed of a motor by controlling an amount of current flowing through a drive coil of the motor. The control circuit comprises a reference voltage circuit that generates a reference voltage corresponding to a speed-specifying signal inputted to specify the rotational speed of the motor; a speed voltage circuit that generates a speed voltage corresponding to an actual rotational speed of the motor; a clamp circuit that limits the level of the speed voltage generated by the speed voltage circuit; a comparator that has the reference voltage generated by the reference voltage circuit and the speed voltage limited in level by the clamp circuit applied thereto and compares the two; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

Abstract: A motor speed control integrated circuit which controls a rotational speed of a motor by controlling the amount of current flowing through a drive coil of the motor. The integrated circuit comprises a first input terminal to have an analog speed-specifying signal in analog amount specifying the rotational speed of the motor input thereto; a second input terminal to have a digital speed-specifying signal in digital amount specifying the rotational speed of the motor input thereto; a reference voltage circuit that generates a reference voltage corresponding to the analog speed-specifying signal and/or the digital speed-specifying signal; a comparator that compares a speed voltage corresponding to the actual rotational speed of the motor and the reference voltage; and a control signal generator that generates and outputs a control signal for controlling the amount of current flowing through the drive coil based on the comparing result of the comparator.

Abstract: A detection device used in an image forming apparatus, comprises a light-emitting element which emits light towards a toner pattern formed on an image carrier, a first light-receiving element which detects the light reflected from the toner pattern and a second light-receiving element which detects the light reflected from the toner pattern in a fashion different from the first light-receiving element. The detection device calculates the amount of toner of the toner pattern based on the output values from the first and second light-receiving elements as well as the position of the toner pattern based on the output value from the first light-receiving element.

Abstract: A method and device for estimating toner concentration in a two-component developer consisting of toner and carrier for an electrophotographic image forming apparatus, and an image forming apparatus equipped with such device. The above method and device calculate an amount of toner charge from data detected by a transferred toner amount sensor, compensate the toner charge based on environmental humidity data and cumulative use period data of the image forming apparatus, and estimate toner concentration. The image forming apparatus equipped with the above device exerts control to predict toner consumption from the estimated toner concentration, supply toner to a developing unit according to the predicted toner consumption, and maintain the toner concentration in the developer at predetermined concentration.

Abstract: A method and device for estimating toner concentration in a two-component developer consisting of toner and carrier for an electrophotographic image forming apparatus, and an image forming apparatus equipped with such device. The above method and device calculate an amount of toner charge from data detected by a transferred toner amount sensor, compensate the toner charge based on environmental humidity data and cumulative use period data of the image forming apparatus, and estimate toner concentration. The image forming apparatus equipped with the above device exerts control to predict toner consumption from the estimated toner concentration, supply toner to a developing unit according to the predicted toner consumption, and maintain the toner concentration in the developer at predetermined concentration.

Abstract: A detection device used in an image forming apparatus, comprises a light-emitting element which emits light towards a toner pattern formed on an image carrier, a first light-receiving element which detects the light reflected from the toner pattern and a second light-receiving element which detects the light reflected from the toner pattern in a fashion different from the first light-receiving element. The detection device calculates the amount of toner of the toner pattern based on the output values from the first and second light-receiving elements as well as the position of the toner pattern based on the output value from the first light-receiving element.