Image forming apparatus with controlled heat sources in fixing unit

Claim 2

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources using a plurality of incrementally variable driving duties per unit time to reach the target temperature.

Claim 3

The image forming apparatus as claimed in claim 1, which further comprises: a detector detecting a temperature of said fixing unit and outputting a detected temperature of said fixing unit and outputting a detected temperature, said control means changing each of the driving duties per unit time based on the detected temperature output from said detector with respect to each of the heat sources.

Claim 4

The image forming apparatus as claimed in claim 1, wherein said control means shifts drive start timings with respect to each of the heat sources.

Claim 5

The image forming apparatus as claimed in claim 3, wherein said control means shifts drive end timings with respect to each of the heat sources.

Claim 6

The image forming apparatus as claimed in claim 1, wherein said control means shifts drive end timings with respect to each of the heat sources.

Claim 7

The image forming apparatus as claimed in claim 1, which further comprises: a plurality of image forming units transferring images on a medium, said control means independently controlling transfer voltages with respect to each of said plurality of image forming units.

Claim 8

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources, wherein said control means shifts drive end timings with respect to each of the heat sources, and wherein said control means includes compensation means for compensating for an insufficient amount of thermal energy generated by the heat sources which are driven by driving a heat source which is originally not driven.

Claim 9

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources, wherein said control means shifts drive end timings with respect to each of the heat sources, and wherein said control means includes compensation means for compensating for an insufficient amount of thermal energy generated by the heat sources which are driven by driving a heat source which is originally not driven.

Claim 10

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources, wherein said control means shifts drive start timings with respect to each of the heat sources, and wherein said control means includes compensation means for compensating for an insufficient amount of thermal energy generated by the heat sources which are driven by driving a heat source which is originally not driven.

Claim 11

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources, wherein said control means shifts drive start timings with respect to each of the heat sources, and wherein said control means includes compensation means for compensating for an insufficient amount of thermal energy generated by the heat sources which are driven by driving a heat source which is originally not driven.

Claim 12

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources, wherein said control means shifts drive start timings with respect to each of the heat sources, and wherein said control means includes compensation means for compensating for an insufficient amount of thermal energy generated by the heat sources which are driven at shifted timings, with respect to each of the heat sources.

Claim 13

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources, wherein said control means shifts drive start timings with respect to each of the heat sources, and wherein said control means includes compensation means for compensating for an insufficient amount of thermal energy generated by the heat sources which are driven at shifted timings, with respect to each of the heat sources.

Claim 14

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources, wherein said control means shifts drive end timings with respect to each of the heat sources, and wherein said control means includes compensation means for compensating for an insufficient amount of thermal energy generated by the heat sources which are driven at shifted timings, with respect to each of the heat sources.

Claim 15

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources, wherein said control means shifts drive end timings with respect to each of the heat sources, and wherein said control means includes compensation means for compensating for an insufficient amount of thermal energy generated by the heat sources which are driven at shifted timings, with respect to each of the heat sources.

Claim 16

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources, wherein said control means includes changing means for changing each of the heat sources which are driven at the shifted timings by other heat sources so as to average serviceable lives of each of the heat sources.

Claim 17

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for setting a target temperature with respect to each of the plurality of heat sources and independently controlling each of the heat sources, wherein said control means includes changing means for changing each of the heat sources which are driven at the shifted timings by other heat sources so as to average serviceable lives of each of the heat sources.

Claim 18

An image forming apparatus comprising: a plurality of image forming units transferring images on a medium; and control means for independently controlling transfer voltages with respect to each of said plurality of image forming units, wherein said control means independently controls timings with which the transfer voltages are applied to each of said image forming units, and wherein said control means controls timings with which the transfer voltages are applied to each of said image forming units so as to maintain relative applying timing relationships of the transfer voltages with respect to said image forming units.

Claim 19

An image forming apparatus comprising: a plurality of image forming units transferring images on a medium; and control means for independently controlling transfer voltages with respect to each of said plurality of image forming units, wherein said control means independently controls timings with which the transfer voltages are applied to each of said image forming units, and wherein said control means controls timings with which the transfer voltages are applied to each of said image forming units so as to maintain relative applying timing relationships of the transfer voltages with respect to said image forming units.

Claim 20

The image forming apparatus as claimed in claim 12, wherein said control means changes the transfer voltages with respect to each of said image forming units depending on a number of image forming units which are driven.

Claim 21

The image forming apparatus as claimed in claim 12, wherein said control means changes the transfer voltages with respect to each of said image forming units depending on an environment of said image forming units.

Claim 22

The image forming apparatus as claimed in claim 14, wherein said control means controls each of the transfer voltages so as to maintain relative magnitude relationships of the transfer voltages with respect to said image forming units.

Claim 23

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for independently controlling each of the plurality of heat sources to achieve a uniform traget temperature for the fixing unit.

Claim 24

An image forming apparatus comprising: a fixing unit having at least one fixing heat roller and a plurality of heat sources with respect to said one fixing heat roller; and control means for independently controlling each of the plurality of heat sources to achieve a uniform traget temperature for the fixing unit.