A printer includes a spectroscope that includes a wavelength-selective interference filter on which light from a measurement target is incident and a carriage moving unit that moves the spectroscope in an X direction with respect to the measurement target. The wavelength-selective interference filter includes a pair of reflecting films and an electrostatic actuator that changes a gap dimension between the pair of reflecting films. A first spectroscopic measurement process that performs spectroscopic measurement while the gap dimension between the reflecting films is decreasing and a second spectroscopic measurement process that performs spectroscopic measurement while the gap dimension is increasing are alternately performed during the movement of the spectroscope by the carriage moving unit in the X direction.

An image forming apparatus includes: an image forming unit including a rotating member; a rotation position detecting unit that detects a rotation position of the rotating member; an image density detecting unit that detects density of an image; an image information analysis unit that analyzes image information; a density profile management unit that manages a density profile; a correction data generation unit that generates correction data; a density correction unit that performs density correction; and a density correction control unit that sets a density correction level, wherein when the density correction level is set at reference accuracy, the density correction unit corrects density, and when the density correction level is set at accuracy higher than the reference accuracy, the density profile management unit forms a corrective patch image and generates a new density profile, the correction data generation unit updates the correction data, and the density correction unit corrects density.

An image forming apparatus includes a photosensitive member, an exposure device, and a developing device. A sensor detects a toner image formed by the developing device to output density information, and a supply device supplies developer to the developing device. In addition, a controller controls the supply device on the basis of a detection result of a supply control toner image formed by the exposure device, a storing portion stores the detection result, and an exchange detecting portion detects information for discriminating exchange of the photosensitive member and the developing device. When the developing device is not exchanged but the photosensitive member is exchanged, the controller executes an operation in a mode in which the controller adjusts an exposure condition for forming the supply control toner image by the exposure device after exchange of the photosensitive member.

An image forming apparatus includes an exposure part forming an electrostatic latent image on a charge region, a developer carrier developing the electrostatic latent image into two types of development images (printing developer image and no-printing developer image), a supply member supplying developer to the developer carrier, a first detection part detecting a first physical quantity correlating to the density of the no-printing developer image, a setting part performing a setting, based on the first physical quantity, for a development voltage applied to the developer carrier or a supply voltage applied to the supply member, a second detection part detecting a second physical quantity correlating to a number of rotations after the print of the printing developer image starts, a correction part correcting, based on the second physical quantity, the development voltage or the supply voltage set by the setting part, and a power source part applying the development voltage to the developer carrier and applies the supply voltage to the supply member.

An image forming apparatus includes an image forming unit having an image carrier, a charging device, and a development device, so as to perform image formation using toner, an exposure device, an image density sensor, a development voltage power supply, a control unit, and a layer thickness detection mechanism. The control unit can perform calibration, in which density of a reference image formed by the image forming unit is detected by the image density sensor, and the development voltage is adjusted based on a detection result, so as to adjust the density of the toner image. The layer thickness detection mechanism detects thickness of the photosensitive layer. Along with a decrease in the thickness of the photosensitive layer detected by the layer thickness detection mechanism, the control unit stepwisely decreases an upper limit value of the DC voltage from a reference value, when adjusting the development voltage in the calibration.