An image forming apparatus includes a developing unit, a transfer unit, a power source unit configured to supply a developing bias voltage to the developing unit and a transfer bias voltage to the transfer unit, and an input device to receive an image density evaluation. A processor performs adjusts the developing bias voltage when an evaluation input indicating a defect in the image density is received. If, after the first adjustment, another evaluation input indicating a defect in image density is received, the processor adjusts one of the developing bias voltage, the transfer bias voltage, or the toner density in the developing unit.

An image forming apparatus includes an image bearer, an image forming section, an image density difference detector, and control circuitry. The image forming section is configured to form a gradation image pattern on a surface of the image bearer. The gradation image pattern includes gradation images having different image densities stepwise in a sub-scanning direction. The image density difference detector is configured to detect image density differences in a main scanning direction of the gradation images. The control circuitry is configured to execute an image density difference correction mode that corrects the image density differences in the main scanning direction based on detection results detected by the image density difference detector.

A measurement apparatus includes a first conveyance path, a second conveyance path, a measuring portion, a third conveyance path and a sheet stacking portion. A sheet discharged out of an image forming apparatus is conveyed toward a downstream apparatus through the first conveyance path. The second conveyance path is branched from the first conveyance path, extended below the first conveyance path, and merged with the first conveyance path. The measuring portion is disposed on the second conveyance path. The third conveyance path is provided above the first conveyance path and is configured to convey the sheet from which a test image has been measured by the measuring portion in the second conveyance path. The sheet stacking portion is provided above the first conveyance path, and the sheet discharged out of the third conveyance path is stacked on the sheet stacking portion.

An image forming apparatus includes a developing unit, a transfer unit, a power source unit configured to supply a developing bias voltage to the developing unit and a transfer bias voltage to the transfer unit, and an input device to receive an image density evaluation. A processor adjusts the developing bias voltage when an evaluation input indicating a defect in the image density is received. If, after the first adjustment, another evaluation input indicating a defect in image density is received, the processor adjusts one of the developing bias voltage, the transfer bias voltage, or the toner density in the developing unit.

An image forming apparatus comprises a first conveyance unit, an image forming unit, a second conveyance unit, a stacking unit, and a control unit. The control unit controls, in a case where a sheet stacking condition of the stacking unit does not satisfy a predetermined stacking condition, the second conveyance unit to convey the sheet at a second conveyance speed that is faster than the first conveyance speed. The control unit controls, in a case where the sheet stacking condition of the stacking unit satisfies the predetermined stacking condition, the second conveyance unit to convey the sheet at a third conveyance speed that is slower than the second conveyance speed.

A downtime relating to formation and detection of a detection image is reduced. An image forming apparatus includes a controller configured to calculate a first conversion unit to convert a gradation of input image data so that density output for the input image data becomes a first density output characteristic based on a first detection result of the detection image detected by a density sensor in a first mode. The controller generates a second conversion unit to convert the gradation of the input image data so that the density output for the input image data becomes a second density output characteristic in a second mode based on the detection result in the first mode and correction information, and further updates the correction information based on a second detection result of the detection image detected by the density sensor in the second mode and the first detection result.

An image forming apparatus includes circuitry, a reader, and an exposure device that drives lighting elements aligned in a main scanning direction to form a first test image. The circuitry acquires density of first sub-areas, into which the first test image is divided in the main scanning direction, and calculates first correction data based on density of each of the first sub-areas and average density of the first sub-areas, to correct light amounts of the lighting elements. The exposure device forms a second test image with the light amounts corrected. The circuitry acquires density of second sub-areas, into which the second test image is divided in the main scanning direction, and calculates second correction data based on density of a second sub-area adjacent to each of the second sub-areas, to further correct the light amounts. The second sub-areas are differently located from the first sub-areas in the main scanning direction.

An image forming apparatus including an image forming unit, a fixing unit, a reading unit, a reference member, and a controller is described. The image forming unit forms an image and a detection image on a sheet. The detection image is used for detecting geometric characteristics of an image to be formed on a sheet by the image forming unit. The fixing unit fixes the image and the detection image formed by the image forming unit on the sheet. The reading unit reads the detection image on the sheet. The controller adjusts geometric characteristics of the image to be formed on a sheet based on a reading result of the detection image by the reading unit, and controls the reading unit to read the reference member and executes shading correction based on a reading result of the reference member.

In a case where a first mode, in which a reader reads test patterns while sheets are fed to the reader by a document feeder, is executed, an image forming apparatus forms a first test pattern on a first sheet and a second test pattern on a second sheet before the first test pattern on the first sheet placed on an original tray of the document feeder is read by the reader. In a case where a second mode, in which the reader reads the test patterns on the sheets without feeding the sheets by the document feeder is executed, the apparatus forms the second test pattern after a reading of the first test pattern on the first sheet is started by the reader.

An image reading apparatus includes a reader, a conveying path, a conveyer, a conveyer housing, and a frame. The conveying path guides the sheet having the image to a reading position and guides the sheet read by the reader in an ejecting direction. The conveyer conveys the sheet along the conveying path. The conveyer housing supports the conveying path and the conveyer. The frame comprises columns and beams that connect adjacent columns. The frame individually fixes the reader and the conveyer housing. The columns are provided with resilient conveying-housing fixing members, the conveying-housing fixing members each having a length smaller than the distance between adjacent columns. The conveying-housing fixing members comprise a material having rigidity lower than the material of the beams. The conveyer housing is fixed to the frame by the conveying-housing fixing members. The reader is fixed to the beams.