An optical device includes: a radiation portion that sends light toward a predetermined position; a lens body including plural lenses that are arranged in an array direction and on which reflection light reflected at the predetermined position is incident; a first support body having a light limiting portion and supporting the radiation portion, the light limiting portion extending in the array direction on the incident side of reflection light relative to the lens body, the light limiting portion limiting incidence of at least a portion of light having an influence on an image based on reflection light; and a second support body supporting the lens body and being movable, relative to the first support body, in an optical axis direction of reflection light.

An image forming apparatus includes an image former; a detector; and a hardware processor that: calculates a minimum area for each of the plurality of tones based on image data of the image, calculates a density ratio between the densities before and after the transferring is made for each of the plurality of tones from the densities detected by the detector, extracts as a first area a minimum area of a tone corresponding to a density ratio which switches from less than a predetermined threshold to equal to or more than the threshold, and extracts as a second area a minimum area of a tone the density ratio of which is a maximum, and changes a setting of a dot size of the image so that a size of the second area becomes the same as a size of the first area until the next setting change is performed.

An image forming apparatus includes an image bearer, a driver, an image forming device, a sensor, and circuitry. The driver drives and rotates the image bearer. The image forming device forms a toner image on the image bearer driven and rotated by the driver. The sensor emits light to the image bearer and receives reflected light. The circuitry controls the driver and the image forming device to form a first toner image with a first color and a second toner image with a second color different from the first color. The circuitry controls the sensor to detect specularly reflected light and diffusely reflected light from the first toner image and the second toner image. The circuitry calculates an amount of misalignment of the first toner image and the second toner image based on a value of the specularly reflected light and a value of the diffusely reflected light.

An image forming apparatus includes a storage unit and a charging amount acquisition unit. The charging amount acquisition unit performs a charging amount acquisition operation for forming a measurement toner image on the image carrier while changing the frequency of the alternating current voltage of the development bias with a potential difference in a direct current voltage between the developing roller and the image carrier being kept constant, acquiring a tilt of a measurement straight line representing a relationship between the change amount of the frequency and a density change amount of the measurement toner image, and acquiring the charging amount of the toner based on the acquired tilt of the measurement straight line and the reference information in the storage unit.

An image forming apparatus includes a developer information acquisition unit. The developer information acquisition unit performs a developer deterioration information acquisition operation. In the developer deterioration information acquisition operation, the developer information acquisition unit acquires a tilt of a measurement straight line representing the relationship between the change amount of the frequency in a first measurement toner image forming operation and the density change amount of the measurement toner image based on the change amount of the frequency in the first measurement toner image forming operation and a result of detecting density of the measurement toner image in a density detecting unit, and acquires a toner charging amount based on the acquired tilt of the measurement straight line and the reference information in the storage unit so as to acquire information relating to deterioration of developer based on the acquired toner charging amount.

An image forming apparatus includes a developing device, an image bearing member, an image density detecting portion, a toner content detecting portion, a humidity sensor, a supplying portion, and a controller configured to control the supplying portion so that a toner content is between an upper limit and a lower limit thereof. The controller can execute setting control in which the target value of the toner content is set on the basis of an image density of a reference toner image. The controller sets the lower limit until execution of subsequent setting control, wherein the lower limit is higher when a humidity is a first humidity and an average image ratio is a first ratio than when the humidity is a second humidity higher than the first humidity and the average image ratio is a second ratio larger than the first ratio.

First correction data for use in a first printing mode is generated by image density measurement in the first printing mode, and second correction data for use in a second printing mode, which is different from the first printing mode in peripheral speed ratio of a developing roller to a photosensitive drum, is generated by image density measurement in the second printing mode. First processing for generating first and second correction data for the first and second printing modes, respectively, by density measurement, or second processing for generating the first correction data by density measurement and generating the second correction data using the generated first correction data and a difference in image density between the first printing mode and the second printing mode is executed. The first processing is executed when a predetermined condition is satisfied.

An image forming apparatus that forms an image on a transfer material in an image forming mode, includes: a photoreceptor rotatable in a predetermined rotation direction; a developer that forms a toner image on the photoreceptor using a two-component developing agent including toner and a carrier; a transferor that transfers the toner image on the photoreceptor onto the transfer material; a carrier collector that applies an electric field corresponding to a collecting bias to a carrier adhering to the photoreceptor to collect the carrier; a carrier detector that detects a carrier remaining on the photoreceptor after collecting the carrier by the carrier collector; and a hardware processor that sets the collecting bias in the image forming mode on the basis of the amount of carriers detected by the carrier detector when a carrier adhesion detecting mode for forcibly causing a carrier to adhere to the photoreceptor is executed.

An image forming apparatus includes a causal member identifying section, and a judgement section. The causal member identifying section identifies the causal member as a cause of the periodic unevenness based on the period of the periodic unevenness which has been detected by the periodic unevenness detector. The judgement section judges whether or not the periodic unevenness is transient based on the information of the causal member identified by the causal member identifying section, the information of at least one of a resting time in which the image forming apparatus has been left inoperative, an operating time of the causal member, and the image forming condition for image formation, and the information of a temperature and a humidity inside the image forming apparatus.

The image forming apparatus transfers an image onto a surface of a sheet at a transfer position on a conveying path. A pair of conveying rollers convey the sheet to the transfer position. The image sensor reads the sheet upstream of the transfer position. The rotary body is disposed to face the image sensor with the conveying path interposed therebetween. The rotary body includes a background portion configured to face a reading surface of the image sensor when the rotary body is at a first rotational position, and a cleaning portion configured to come into contact with the reading surface of the image sensor when the rotary body is at a second rotational position.