Abstract: An image forming apparatus includes an image forming unit and developing containers. The image forming unit includes developing stations to form an image on a print medium with toners, based on input image data. The developing containers contain the toners and are attachable to and detachable from the developing stations. The developing containers include a first developing container containing a first toner and a second developing container containing a second toner having a higher luminescence intensity under invisible light than the first toner. The first toner and the second toner are toners that form an image having a higher luminescence intensity under the invisible light than under visible light. The image forming unit adheres the second toner to the print medium before adhering the first toner when the image forming unit superimposes the first toner and the second toner one atop another on the print medium.

Abstract: An image forming apparatus includes an image bearer, a toner image forming device, a plurality of image density detectors, and a controller. The plurality of image density detectors are disposed at predetermined intervals opposite the image bearer in a width direction of the image bearer. The controller causes the toner image forming device to form toner image patterns having an identical density at the plurality of positions on the image bearer and the plurality of image density detectors detects a density of the toner image patterns. Based on the detected density of the toner image patterns, the controller identifies multiple cyclic fluctuations of the density of the toner image patterns and adjusts an image forming condition based on the multiple cyclic fluctuations of the density of the toner image patterns to decrease an amplitude caused by the multiple cyclic fluctuations of the density of the toner image patterns.

Abstract: An image forming apparatus includes a toner pattern bearer to bear a first toner pattern having a first image area and a second toner pattern having a second image area different from the first image area. A toner adhesion amount detector detects a toner adhesion amount of toner of each of the first toner pattern and the second toner pattern. A toner degradation rate calculator calculates a first deviation in the toner adhesion amount of the first toner pattern and a second deviation in the toner adhesion amount of the second toner pattern based on the toner adhesion amount detected by the toner adhesion amount detector. The toner degradation rate calculator compares the first deviation with the second deviation and calculates a toner degradation rate based on a comparison result.

Abstract: An image forming apparatus includes an image bearer, a toner image forming device, a plurality of image density detectors, and a controller. The plurality of image density detectors are disposed at predetermined intervals opposite the image bearer in a width direction of the image bearer. The controller causes the toner image forming device to form toner image patterns having an identical density at the plurality of positions on the image bearer and the plurality of image density detectors detects a density of the toner image patterns. Based on the detected density of the toner image patterns, the controller identifies multiple cyclic fluctuations of the density of the toner image patterns and adjusts an image forming condition based on the multiple cyclic fluctuations of the density of the toner image patterns to decrease an amplitude caused by the multiple cyclic fluctuations of the density of the toner image patterns.

Abstract: An image forming apparatus includes a toner pattern bearer to bear a first toner pattern having a first image area rate and a second toner pattern having a second image area rate different from the first image area rate. A toner adhesion amount detector detects a toner adhesion amount of toner of each of the first toner pattern and the second toner pattern. A toner degradation rate calculator calculates a first deviation in the toner adhesion amount of the first toner pattern and a second deviation in the toner adhesion amount of the second toner pattern based on the toner adhesion amount detected by the toner adhesion amount detector. The toner degradation rate calculator compares the first deviation with the second deviation and calculates a toner degradation rate based on a comparison result.