An image forming apparatus includes a photosensitive member, an exposing unit exposes the photosensitive member to exposure light to form an electrostatic latent image, a developing unit develops the electrostatic latent image to form an image, an intermediate transfer member onto which the image on the photosensitive member is transferred, a measurement unit measures a measurement image on the intermediate transfer member, an adjustment unit adjusts gradation characteristics based on the measurement result of the measurement unit, and correction unit corrects intensity of the exposure light for each of a plurality of positions on the photosensitive member in a scanning direction. the correction unit corrects the intensity based on the correction amount with respect to the intensity corresponding to a predetermined position. the predetermine position corresponds to a position in the scanning direction, at which the measurement image is formed.

An image forming apparatus includes an image forming unit and a controller. The image forming unit includes a latent image bearer, a charger to charge the latent image bearer, an exposure device to expose a latent image on the surface of the latent image bearer, and a developing device to develop the latent image with a developer. The controller executes an image forming process, a first fluctuation control that cyclically changes a developing bias supplied to the developing device based on predetermined first pattern data, and a second fluctuation control that cyclically changes a charging bias supplied to the charger based on predetermined second pattern data, in parallel. The controller executes a determination process to determine whether the controller executes the first fluctuation control. When the controller determines not to execute the first fluctuation control, the controller determines not to execute the second fluctuation control, too.

An image forming apparatus includes a light-receiving unit that includes light-receiving elements arranged along a movement direction of a target formed on an image carrier, and is arranged so as to receive light emitted from a light-emitting unit and specularly reflected off the image carrier; a member configured to limit a size, in the movement direction, of diffused reflection light that is incident on the light-receiving unit; a selection unit configured to select whether or not each of the light-receiving elements in the light-receiving unit is an effective light-receiving element; a generation unit configured to generate a detection signal from an output of the effective light-receiving element; and a detection unit configured to detect a target formed on the image carrier based on the detection signal.

A toner detection unit includes an LED and a light receiving element that outputs a current in accordance with a received light amount. A current/voltage converter circuit converts the current outputted from the light receiving element into a voltage and outputs the voltage. A voltage amplifier circuit amplifies a difference between the voltage outputted from the converter circuit and a reference voltage and outputs the amplified difference as a voltage corresponding to the received light amount. A microcomputer measures the voltage outputted from the voltage amplifier circuit by causing the LED to emit light, under a measurement condition under which the reflected light is not incident on the light receiving element through an opening formed in a housing of the toner detection unit, and adjusts the reference voltage used in the voltage amplifier circuit based on the obtained measured voltage.

Provided is an image forming apparatus capable of reducing the time required for calibration of an image forming condition. The image forming apparatus includes image forming portions configured to form images onto photosensitive drums, an intermediate transfer member onto which the images are sequentially transferred from the photosensitive drums, and a density detection sensor. The density detection sensor starts measuring a base surface density of the intermediate transfer member before a measurement image is formed on the intermediate transfer member. When a measurement start position of the base surface density reaches a transfer position of an image of an image forming portion located at the most upstream position in a rotation direction of the intermediate transfer member, the image forming apparatus causes the image forming portion to start forming the measurement image.

An image forming apparatus includes a first image forming unit configured to form a first image in a chromatic color, a second image forming unit configured to form a second image in black, an intermediate transfer member, a sensor, a first adjustment unit configured to adjust the image forming position for the black based on an adjustment value, a second adjustment unit configured to adjust image forming position based on an adjustment condition, and a generation unit configured to generate the adjustment condition. The generation unit generates a first adjustment condition based on a user instruction relating to a first test image having chromatic color on a sheet input from the input unit. The generation unit generates a second adjustment condition based on the reading result of the second test image having black on a sheet from a reading device.

An image forming apparatus includes an image forming portion for forming an image, a human presence sensor for detecting presence of a human body adjacent the apparatus, and a controller capable of executing an adjustment process operation for the image forming portion when a first predetermined number of prints are produced. When the human presence sensor detects a human body in the neighborhood of the apparatus, the execution of the adjustment process operation is deferred to reduce the waiting time necessitated by the adjustment operation, but if a second predetermined number of prints are produced, the image forming operation of the image forming portion is interrupted, and the deferred adjustment process is executed.

An image forming apparatus includes a photo sensor, which is configured to detect a measurement image formed on an intermediate transfer belt, and a controller. The controller includes a first comparator, a second comparator, an XOR unit, and a CPU. The first comparator is configured to binarize an analog detection waveform, which represents a detection result of a measurement image by the photo sensor, in accordance with a first threshold value to generate a first binary signal. The second comparator is configured to binarize the detection waveform in accordance with a second threshold value to generate a second binary signal. The XOR unit is configured to perform an XOR operation in accordance with the first binary signal and the second binary signal to generate an XOR signal.

The image-forming apparatus includes multiple developing units that form images using multiple color developers, an image carrier that, in color displacement detection, carries the developers transferred thereon at mutually different image-carrying positions, an optical sensor that projects a light to the image carrier and receives a reflected light from the image carrier, and an acquirer that acquires, in response to output from the optical sensor, passage times at which the developers on the image carrier respectively pass a detection position. The optical sensor receives a diffusively reflected light from a non-transferred area of the image carrier on which the developers are not transferred. The acquirer acquires the passage times of all the developers, in response to changes in the output from the optical sensor at an output level higher than that corresponding to a diffusively reflected light from the developers on the image carrier.

An image defect predictive diagnostic apparatus includes an acquisition unit and a notification unit. The acquisition unit acquires first characteristic values and second characteristic values from an image forming apparatus that forms an image by using an electrophotographic process. The first characteristic values include at least one of (i) toner concentrations and (ii) developing potentials. The first characteristic values have an influence on developability. The second characteristic values are different from the first characteristic values. The notification unit predicts occurrence of a dot image which has no relationship with the image by using the first characteristic values and the second characteristic values which are acquired by the acquisition unit, and that makes notification.