An image forming apparatus includes a developing current detecting portion, a control portion, and a deviation detecting portion. The developing current detecting portion detects a developing current that flows between a developing device and a photoconductor drum during development of an electrostatic latent image. The control portion causes the exposure device to form electrostatic latent images of at least two patch images at different positions from each other and at different timings from each other in a main scanning direction. The deviation detecting portion detects deviation of one of the exposure device and the photoconductor drum with respect to the other based on a detection timing at which the developing current is detected during development of the electrostatic latent images of the at least two patch images.

An image forming apparatus includes a developing current detecting portion, a control portion, and a deviation detecting portion. The developing current detecting portion detects a developing current that flows between a developing device and a photoconductor drum during development of an electrostatic latent image. The control portion causes the exposure device to form electrostatic latent images of at least two patch images at different positions from each other and at different timings from each other in a main scanning direction. The deviation detecting portion detects deviation of one of the exposure device and the photoconductor drum with respect to the other based on a detection timing at which the developing current is detected during development of the electrostatic latent images of the at least two patch images.

Provided are: an exposure device being configured to perform multiple exposure with the second light-emitting element array to a place exposed with the first light-emitting element array; and a controller configured to transmit a signal for controlling the exposure device, in which the exposure device sets a first pulse signal for light emission of the first light-emitting element array, based on a first delay time and a first pulse width, sets a second pulse signal for light emission of the second light-emitting element array, based on a second delay time, different from the first delay time, and a second pulse width, identical to the first pulse width, and starts and terminates light emission of each of the first light-emitting element array and the second light-emitting element array, according to the set first pulse signal and second pulse signal.

Provided are: an exposure device being configured to perform multiple exposure with the second light-emitting element array to a place exposed with the first light-emitting element array; and a controller configured to transmit a signal for controlling the exposure device, in which the exposure device sets a first pulse signal for light emission of the first light-emitting element array, based on a first delay time and a first pulse width, sets a second pulse signal for light emission of the second light-emitting element array, based on a second delay time, different from the first delay time, and a second pulse width, identical to the first pulse width, and starts and terminates light emission of each of the first light-emitting element array and the second light-emitting element array, according to the set first pulse signal and second pulse signal.

An image forming apparatus includes plural photosensitive members, a scanner unit for scanning the photosensitive members, and a fixing unit for fixing toner images. The scanner unit includes a rotatable polygonal mirror for reflecting laser beams emitted in correspondence to respective photosensitive members, reflecting members for reflecting the laser beams, and a box for accommodating the polygonal mirror and the reflecting members. The box includes plural outlets for the laser beams. Of the reflecting members, first and second reflecting members reflect laser beams toward corresponding first and second outlets respectively positioned farthest from and closest to the fixing unit. A distance between the first outlet and its corresponding photosensitive member is longer than a distance between the second outlet and its corresponding photosensitive member, whereas a distance between the first reflecting member and the polygonal mirror is shorter than a distance between the second reflecting member and the polygonal mirror.

An image forming apparatus includes a converter configured to convert image data with use of a tone correction condition corresponding to a position in a main scanning direction of the image data, and an image forming unit, which includes a photosensitive member and an exposure portion configured to expose the photosensitive member to light based on the converted image data, and is configured to form an image on a recording medium. The image forming apparatus further includes a holding portion configured to hold a plurality of feedback conditions corresponding to a plurality of tones and a controller configured to control the image forming unit to form a plurality of test images, acquire measurement results for the plurality of test images, and generate the tone correction condition based on the measurement results and the plurality of feedback conditions.

An image forming apparatus includes a photosensitive drum which is rotatable; light-emitting portions arranged along a direction of a rotational axis of the photosensitive drum, the light-emitting portions emitting light based on image data in order to expose the photosensitive drum; a reference clock signal generation portion which generates a reference clock signal with a predetermined period; a modulated clock signal generation portion which generates a modulated clock signal with a predetermined modulation period by spreading a spectrum of the reference clock signal and by modulating the predetermined period, wherein the light-emitting portions emit light for a lighting time set based on the modulated clock signal; and a control signal generation portion which generates with a period of n times the predetermined modulation period (n is an integer greater than or equal to 1) a control signal for controlling a timing at which the light-emitting portions emit light.

An image forming apparatus includes a photosensitive drum which is rotatable; light-emitting portions arranged along a direction of a rotational axis of the photosensitive drum, the light-emitting portions emitting light based on image data in order to expose the photosensitive drum; a reference clock signal generation portion which generates a reference clock signal with a predetermined period; a modulated clock signal generation portion which generates a modulated clock signal with a predetermined modulation period by spreading a spectrum of the reference clock signal and by modulating the predetermined period, wherein the light-emitting portions emit light for a lighting time set based on the modulated clock signal; and a control signal generation portion which generates with a period of n times the predetermined modulation period (n is an integer greater than or equal to 1) a control signal for controlling a timing at which the light-emitting portions emit light.

Provided is an image formation device including a photoreceptor configured to carry a toner image and a developer configured to form the toner image on a surface of the photoreceptor and configured such that the developer is a replaceable development unit, the image formation device including: a development bias application section configured to apply a development bias to between the photoreceptor and the developer; a stabilization control section configured to perform image stabilization control of determining a development bias value to be used in future by changing the development bias while measuring a density of the toner image formed by the developer, thereby obtaining the toner image with a target density; and a life determination section configured to determine expiration of use of the development unit when the development bias value determined by the stabilization control falls outside a preset acceptable range.

A control portion executes: a step of calculating a surface potential of an image bearing member charged by a charging member, to which a predetermined voltage is applied, and exposed to light by a predetermined exposure amount on the basis of a discharge start voltage between a measurement member and the image bearing member and calculating a correction value from a difference between a target value and calculated surface potential of the image bearing member; a step of correcting calculated surface potential of the image bearing member on the basis of the correction value; and a step of controlling at least one of the voltage applied to the charging member and an exposure amount of the exposure apparatus on the basis of the corrected surface potential of the image bearing member so that the surface potential of the image bearing member reaches the target value.