Initialisation of a fuser unit in an image-forming apparatus

Claim 1

Image-forming apparatus of the kind including a fuser unit (14) having a heated roller (10) and a backup roller (12), which rollers are pressed one against the other, there being rotary drive means (300) connected with one of the said rollers to bring about rotation of both rollers so that, when the apparatus is in use, a sheet-form medium (16) bearing a toner image is gripped between the two rollers and carried therebetween to cause the toner image to become fixed onto the sheet-form medium, and also including warm-up control means (244) operable to cause the apparatus to undergo a predetermined initialisation procedure, for setting mechanical and electrostatic conditions of the apparatus into a desired state of readiness, substantially throughout which procedure the said rollers are rotated and a heater (310) of the heated roller (10) is energised to increase surface temperature of that roller, the said warm-up control means (244) being operative to cause the rotation of the said rollers to stop upon termination of the initialisation procedure whilst maintaining energisation of the said heater (310), in dependence upon surface-temperature monitoring means associated with the said heated roller, until the said surface temperature attains a preselected desired value, whereupon the apparatus is switched into a ready-for-­use condition; characterised in that the said warm-up control means (244) are operative to ensure that if the said preselected desired value of the said surface temperature is not attained within a first preset time interval (T1 - T9), following termination of the said initialisation procedure, the said rollers (10, 12) are subjected to rotation again, whilst energisation of the said heater (310) is maintained in dependence upon the said surface-temperature monitoring means, until the said preselected desired value is attained or until expiry of a second preset time interval (T6 - T1), following expiry of the said first preset time interval (T1 - T9), whichever is the first to occur.

Claim 3

A method of controlling a fuser unit (14) of an image-forming apparatus in a warming-up stage, which unit (14) comprises a heat roller (10) and a backup roller (12) pressed against the heat roller (10), and between which rollers (10, 12) a sheet medium (16, 202) is nipped so that a toner image carried on the sheet medium (16, 202) is fixed, characterized in that said method comprises steps of: starting the energization of a heater (310) of the heat roller (10) substantially at the same time as the commencement of an initialization process of mechanical and electrostatic conditions of the machine while rotating the heat roller (10) and the backup roller (12) together; stopping the rotation of the rollers (10, 12) after the initialization process has been completed; monitoring a surface temperature of the heat roller (10) for a first predetermined period (T1 - T9) after the completion of the initialization; and when the surface temperature has reached a set value within the first predetermined period (T1 - T9), determining that the fuser unit (14) is ready for operation, and when the set value is not reached within the first predetermined period, carrying out an additional warming-up process involving rotating the heat roller (10) and the back-up roller (12) again until the set value is reached, unless a second predetermined period (T6 - T1) has expired subsequent to the expiration of the first predetermined period.

Claim 4

A method of controlling a fuser unit (14) of an image-forming apparatus in a warming-up stage, which unit (14) comprises a heat roller (10) and a backup roller (12) pressed against the heat roller (10), and between which rollers (10, 12) a sheet medium (16, 202) is nipped so that a toner image carried on the sheet medium (16, 202) is fixed, characterized in that said method comprises steps of: starting the energization of a heater (310) of the heat roller (10) substantially at the same time as the commencement of an initialization process of mechanical and electrostatic conditions of the machine while rotating the heat roller (10) and the backup roller (12) together; stopping the rotation of the rollers (10, 12) after the initialization process has been completed; monitoring a surface temperature of the heat roller (10) for a first predetermined period (T1 - T9) after the completion of the initialization; and when the surface temperature has reached a set value within the first predetermined period (T1 - T9), determining that the fuser unit (14) is ready for operation, and when the set value is not reached within the first predetermined period, carrying out an additional warming-up process involving rotating the heat roller (10) and the back-up roller (12) again until the set value is reached, unless a second predetermined period (T6 - T1) has expired subsequent to the expiration of the first predetermined period.

Claim 5

A method of controlling a fuser unit of an image-forming apparatus in a warming-up stage, in which apparatus substantially all rotating elements in the apparatus are driven by a single main motor (300) and in which the fuser unit (14) comprises a heat roller (10) and a back-up roller (12) pressed against the heat roller (10), and between which rollers (10, 12) a sheet medium (16, 202) is nipped so that a toner image carried on the sheet medium (16, 202) is fixed, characterized in that said method comprises steps of: starting the energization of a heater (310) of the heat roller (10) substantially at the same time as the commencement of an initialization process of mechanical and electrostatic conditions of the machine while rotating the heat roller (10) and the backup roller (12) together; stopping the rotation of the rollers (10, 12) after the initialization has been completed; monitoring a surface temperature of the heat roller (10) for a first predetermined period (T1 - T9) after the completion of the initialization ; and when the surface temperature has reached a set value within the first predetermined period (T1 - T9), determining that the fuser unit (14) is ready for operation; and when the set value is not reached within the first predetermined period, carrying out an addi­tional warming-up process involving rotating the heat roller (10) and the back-up roller (12) again until the set value is reached, unless a second predetermined period (T6 - T1) has expired subsequent to the expira­tion of the first predetermined period (T1 - T9).

Claim 6

A method of controlling a fuser unit of an image-forming apparatus in a warming-up stage, in which apparatus substantially all rotating elements in the apparatus are driven by a single main motor (300) and in which the fuser unit (14) comprises a heat roller (10) and a back-up roller (12) pressed against the heat roller (10), and between which rollers (10, 12) a sheet medium (16, 202) is nipped so that a toner image carried on the sheet medium (16, 202) is fixed, characterized in that said method comprises steps of: starting the energization of a heater (310) of the heat roller (10) substantially at the same time as the commencement of an initialization process of mechanical and electrostatic conditions of the machine while rotating the heat roller (10) and the backup roller (12) together; stopping the rotation of the rollers (10, 12) after the initialization has been completed; monitoring a surface temperature of the heat roller (10) for a first predetermined period (T1 - T9) after the completion of the initialization ; and when the surface temperature has reached a set value within the first predetermined period (T1 - T9), determining that the fuser unit (14) is ready for operation; and when the set value is not reached within the first predetermined period, carrying out an addi­tional warming-up process involving rotating the heat roller (10) and the back-up roller (12) again until the set value is reached, unless a second predetermined period (T6 - T1) has expired subsequent to the expira­tion of the first predetermined period (T1 - T9).