Fixing control method and apparatus

A fixing control apparatus for performing a fixing process by using a heat roller heated by an induction heating coil, comprising:

• a first temperature sensor positioned, around said heat roller, within a range of ±45° from a portion where maximum heat is generated by said induction heating coil;
• a second temperature sensor positioned, around said heat roller, within a range of ±45° from a portion where minimum heat is generated by said induction heating coil;
• a central processing unit for performing switching control of a fixing control temperature concerning the temperature of said heat roller on the basis of temperatures sensed by said first and second temperature sensors;
• and
• an environmental temperature sensor for sensing an environmental temperature,
• wherein when power supply to said induction heating coil is started, said central processing unit changes at least one of the fixing control temperature, a pre-run start temperature at which pre-run is started, and a ready display temperature pertaining to temperature display in a ready state, on the basis of the temperatures sensed by said first and second temperature sensors,
• wherein on the basis of the environmental temperature sensed by said environmental temperature sensor, said central processing unit changes at least one of the fixing control temperature, the pre-run start temperature, and the ready display temperature, and
• wherein
• in a normal environment in which the environmental temperature sensed by said environmental temperature sensor is higher than a threshold value, said central processing unit lowers the fixing control temperature whenever a predetermined time elapses while the temperature sensed by said first or second temperature sensor is lower than a first predetermined value, and, if the temperature sensed by said first and second temperature sensor becomes higher than the first predetermined value, maintains the fixing control temperature set at that point, and
• in a low-temperature environment in which the environmental temperature sensed by said environmental temperature sensor is lower than the threshold value, said central processing unit maintains, while the temperature sensed by said first or second temperature sensor is lower than a second predetermined value higher than the first predetermined value, the fixing control temperature at a temperature held at that point, and, if the temperature sensed by said first and second temperature sensor becomes higher than the second predetermined value, keeps the fixing control temperature lower than the temperature set at that point.

A fixing control apparatus for performing a fixing process by using a heat roller heated by an induction heating coil, comprising:

• a first temperature sensor positioned, around said heat roller, within a range of ±45° from a portion where maximum heat is generated by said induction heating coil;
• a second temperature sensor positioned, around said heat roller, within a range of ±45° from a portion where minimum heat is generated by said induction heating coil;
• and
• a central processing unit for performing switching control of a fixing control temperature concerning the temperature of said heat roller on the basis of temperatures sensed by said first and second temperature sensors,
• wherein
• at the start of printing, said central processing unit changes the fixing control temperature on the basis of the temperatures sensed by said first and second temperature sensors,
• said fixing control apparatus further comprises an environmental temperature sensor for sensing an environmental temperature, and
• on the basis of the environmental temperature sensed by said environmental temperature sensor, said central processing unit changes, in accordance with a sheet to be printed, the fixing control temperature and a threshold value for determining whether an environment is a normal environment or a low-temperature environment on the basis of the environmental temperature sensed by said environmental temperature sensor.

A fixing control apparatus for performing a fixing process by using a heat roller heated by an induction heating coil, comprising:

• a first temperature sensor positioned, around said heat roller, within a range of ±45° from a portion where maximum heat is generated by said induction heating coil;
• a second temperature sensor positioned, around said heat roller, within a range of ±45° from a portion where minimum heat is generated by said induction heating coil;
• and
• a central processing unit for performing switching control of a fixing control temperature concerning the temperature of said heat roller on the basis of temperatures sensed by said first and second temperature sensors,
• wherein
• during printing, said central processing unit changes the fixing control temperature for each sheet to be printed whenever a predetermined time elapses, on the basis of a result of comparison of the temperatures sensed by said first and second temperature sensors with a lower-limiting threshold value of a printing permissible range,
• said fixing control apparatus further comprises an environmental temperature sensor for sensing an environmental temperature, and
• on the basis of the environmental temperature sensed by said environmental temperature sensor, said central processing unit changes the lower-limiting threshold value.

A fixing control method of performing a fixing process by using a heat roller heated by an induction heating coil,

• wherein switching control of a fixing control temperature concerning the temperature of the heat roller is performed on the basis of a temperature sensed by a first temperature sensor positioned, around the heat roller, within a range of ±45° from a portion where maximum heat is generated by the induction heating coil, and a temperature sensed by a second temperature sensor positioned, around the heat roller, within a range of ±45° from a portion where minimum heat is generated by the induction heating coil,
• wherein when power supply to the induction heating coil is started, at least one of the fixing control temperature, a pre-run start temperature at which pre-run is started, and a ready display temperature pertaining to temperature display in a ready state is changed on the basis of the temperatures sensed by the first and second temperature sensors,
• wherein on the basis of an environmental temperature sensed using an environmental temperature sensor, at least one of the fixing control temperature, the pre-run start temperature, and the ready display temperature is changed, and
• wherein the fixing control temperature is lowered as the temperature sensed by the first or second temperature sensor rises.

A fixing control method of performing a fixing process by using a heat roller heated by an induction heating coil,

• wherein switching control of a fixing control temperature concerning the temperature of the heat roller is performed on the basis of a temperature sensed by a first temperature sensor positioned, around the heat roller, within a range of ±45° from a portion where maximum heat is generated by the induction heating coil, and a temperature sensed by a second temperature sensor positioned, around the heat roller, within a range of ±45° from a portion where minimum heat is generated by the induction heating coil, and
• wherein
• at the start of printing, the fixing control temperature is changed on the basis of the temperatures sensed by the first and second temperature sensors, and
• on the basis of an environmental temperature sensed by an environmental temperature sensor, the fixing control temperature and a threshold value for determining whether an environment is a normal environment or a low-temperature environment on the basis of the environmental temperature sensed by the environmental temperature sensor, are changed in accordance with a sheet to be printed.

A fixing control method of performing a fixing process by using a heat roller heated by an induction heating coil,

• wherein switching control of a fixing control temperature concerning the temperature of the heat roller is performed on the basis of a temperature sensed by a first temperature sensor positioned, around the heat roller, within a range of ±45° from a portion where maximum heat is generated by the induction heating coil, and a temperature sensed by a second temperature sensor positioned, around the heat roller, within a range of ±45° from a portion where minimum heat is generated by the induction heating coil, and
• wherein
• during printing, the fixing control temperature is changed for each sheet to be printed whenever a predetermined time elapses, on the basis of a result of comparison of the temperatures sensed by the first and second temperature sensors with a lower-limiting threshold value of a printing permissible range, and
• on the basis of an environmental temperature sensed by an environmental temperature sensor, the lower-limiting threshold value is changed.