An image forming apparatus includes an image bearer, an image forming device to form a toner image on the image bearer, a transfer device to transfer the toner image to a recording medium, a line sensor as an image density sensor to detect image density of the toner image, and a controller operatively connected to the image density sensor. The image density sensor is disposed so as to be shorter in a rotational direction of the image bearer than in a width direction of the image bearer perpendicular to the rotational direction of the image bearer. The controller forms a shading pattern image including a plurality of patches on the image bearer, and detects image density of the plurality of patches, so as to control image density. The shading pattern image is shorter in the rotational direction of the image bearer than in the width direction of the image bearer.

A toner detection unit is configured by an LED that irradiates light toward an intermediate transfer belt, first and second light receiving elements that respectively receive specular reflection light and diffused reflection light of light irradiated toward the intermediate transfer belt from the LED, a circuit board, and a housing. The LED and the light receiving elements are mounted in a line on the circuit board. The housing is configured to guide, to the first light receiving element, the specular reflection light from a first region within an irradiation region on which light is irradiated from the LED on the intermediate transfer belt, and to guide, to the second light receiving element, the diffused reflection light from a second region which is different to the first region within the irradiation region.

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 for 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.

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 of diffused reflection light that is incident on the light-receiving unit in the movement direction; a selection unit configured to select whether or not each of the light-receiving elements in the light-receiving unit is a 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.

An image forming apparatus includes upstream-side and downstream-side detection parts and a control section. The detection parts are disposed on a moving path of an intermediate transfer belt or a conveyor belt and detect a speed of the belt. The control section performs control to correct color misregistration of images composed of colors to be formed on the intermediate transfer belt or a recording medium conveyed by the conveyance belt on the basis of the detection result. The control unit calculates a difference between the speed detected by the upstream-side detection part and the speed detected by the downstream-side detection part after a predetermined time elapses since the upstream-side detection part detects the speed and performs the control on the basis of the difference. The predetermined time is obtained by dividing a distance between the detection parts by a target speed of the belt.

An image forming apparatus that is capable of determining whether a measurement image is formed normally. First and second image forming units form first and second images on an image bearing member using first and second color toners. Reflectance of first toner is higher than the image bearing member and is higher than the second toner. A controller controls image forming units to form first and second measurement images superimposed. A correction unit corrects a positional relationship between the first and second images based on a position of the first measurement image detected based on an output timing of a signal indicating that the received light amount is not less than a threshold. A prohibition unit prohibits the correction unit from correcting the positional relationship when a period during which the signal is output is different from a predetermined period.

An image forming apparatus includes an image carrying member, a developing device, a cleaning unit and a processor. The developing device performs development with a developer containing a toner and a lubricant. The processor obtains information on a lubricant amount in the developing device; obtains, with respect to each section formed by dividing a surface of the image carrying member in a rotating shaft direction of the image carrying member, a partial coverage from electrostatic latent image writing information for a predetermined period about the section; sets, for the section having the partial coverage of a predetermined value or less, a developer supply amount for a patch to be formed outside an image forming region on the image carrying member, based on the above information; and causes the developing device to supply the set developer supply amount so that the patch is formed.

An image forming apparatus includes an image forming device for forming a pattern image having unit images on a photosensitive member, a sensor for irradiating the pattern image with light and detecting reflected light, and a controller for controlling the image forming device to form a pattern image for printing used when printing and a pattern image for detection to be detected by the sensor on the photosensitive member. A first pattern image for printing includes a predetermined number of first unit images arranged to be spaced from each other, each of the first unit images being smaller than a predetermined size. A first pattern image for detection corresponding to the first pattern image for printing includes more than the predetermined number of the first unit images arranged to be spaced from each other.

An image forming apparatus includes: a detection unit configured to detect a detection pattern on a first region in a first misregistration state and the detection pattern on a second region in a second pattern in a second misregistration state, and a control unit configured to perform misregistration correction by obtaining a misregistration amount in the main scanning direction based on a detection result of the detection pattern. The detection pattern has a first edge that is tilted by a first angle with respect to the main scanning direction on the first region, and has a second edge that is running in the main scanning direction or tilted by a second angle, which is smaller than the first angle, with respect to the main scanning direction on the second region.

Precise correction of a position of a toner image formed by an image forming station can be accomplished in a device using two-component developer. An electrostatic latent image for forming a color misregistration correction pattern for color misregistration correcting includes a first latent image pattern and a second latent image pattern at a position downstream of the first latent image pattern with respect to the moving direction of the electrostatic latent image. The toner image resulting from the development of the first latent image pattern has a width, measured in the image moving direction, which is greater than that of the toner image resulting from the development of a latent image pattern alone, which is the same as the first latent image pattern, or the toner image resulting from the development of the first latent image pattern has an image density at a downstream end portion with respect to the moving direction, which density is higher than that of the toner image resulting from the development of the latent image pattern alone, which is the same as the first latent image pattern.