Image forming apparatus

摘要

An image forming apparatus includes an adjustment sequence controller that causes first to third adjustment processes to be executed. In the first adjustment process, if a second registration mark having reduced calculation errors of shifts of toner-image formation positions as compared with those of a first registration mark is formed in a normal way, the toner-image formation positions are adjusted by using the second registration mark. In the second adjustment process, if the second registration mark is not formed in the normal way, the toner-image formation positions are adjusted by using the first registration mark. In the third adjustment process, if the second registration mark is formed in the normal way after the second adjustment process, the toner-image formation positions are adjusted by using the second registration mark.

主权项

1. An image forming apparatus comprising:
a plurality of toner-image forming units that respectively use toners of a plurality of colors and form a plurality of toner images of different colors; a transferred member that moves along the plurality of toner-image forming units and receives transfer of the plurality of toner images formed by the plurality of toner-image forming units; a transfer member that further transfers the toner images of the plurality of colors transferred on the transferred member, on a recording medium; a fixing unit that fixes the toner images of the plurality of colors transferred on the recording medium, to the recording medium; a mark formation controller that causes the plurality of toner-image forming units to form a registration mark including a set of toner patterns for detection of shifts of toner-image formation positions of the plurality of toner-image forming units, on the transferred member; a mark sensor that detects positions of the toner patterns included in the registration mark formed on the transferred member; a formation-position shift calculator that calculates the shifts of the toner-image formation positions of the plurality of toner-image forming units based on the detection result of the mark sensor; a mark judging unit that judges whether or not the registration mark detected by the mark sensor is a normal mark having accuracy enough for the calculation of the shifts of the toner-image formation positions of the plurality of toner-image forming units, based on the detection result of the mark sensor; a formation-position adjuster that adjusts the toner-image formation positions of the plurality of toner-image forming units based on the calculation result of the formation-position shift calculator; and an adjustment sequence controller,
wherein the adjustment sequence controller causes a first adjustment process to be executed by forming a second registration mark from among a first registration mark and the second registration mark, judging whether or not the second registration mark is a normal mark based on the detection result for the second registration mark, calculating the shifts of the toner-image formation positions based on the detection result for the second registration mark if it is judged that the second registration mark is the normal mark, and adjusting the toner-image formation positions based on the calculation result, the first registration mark including a set of first toner patterns, the second registration mark including a set of toner patterns having a second toner pattern, the second toner pattern being a toner pattern for detection of a shift of a toner-image formation position of at least one toner-image forming unit, the second toner pattern being formed by combining a first toner used by the at least one toner-image forming unit and a second toner used by another toner-image forming unit other than the at least one toner-image forming unit to reduce a calculation error of the shifts of the toner-image formation positions with the second toner pattern as compared with a calculation error with the first toner patterns,wherein the adjustment sequence controller causes a second adjustment process to be executed by forming the first registration mark if it is judged that the second registration mark is not the normal mark, judging whether or not the first registration mark is a normal mark based on the detection result for the first registration mark, calculating the shifts of the toner-image formation positions based on the detection result for the first registration mark if it is judged that the first registration mark is the normal mark, and adjusting the toner-image formation positions based on the calculation result, andwherein the adjustment sequence controller then causes a third adjustment process to be executed by forming the second registration mark, judging whether or not the second registration mark is the normal mark based on the detection result for the second registration mark, calculating the shifts of the toner-image formation positions based on the detection result for the second registration mark if it is judged that the second registration mark is the normal mark, and adjusting the toner-image formation positions based on the calculation result.