Patent ID: 6532348
Filing Date: 2003-03-11
Classification: G03G

Abstract:
A device for generation and adjustment of predetermined temperature values (T1, T2, and T3) at a fixing roller (FR) of a fixing unit, which is mounted in a copy machine and can be switched over to different operational states (W, A, F) for fixing imaging material (P) carrying toner images, whereby the fixing roller, which can rotate, along with a pressure roller (PR) parallel to the axis of the fixing roller and in contact with its outer surface (FS) provide a fixing nip (N) for feeding through imaging material carrying toner images; said device comprising: a heating unit (H1) for said fixing roller, said heating unit, connected to a control/adjustment unit (CU), can be switched for generation and adjustment of predetermined temperature values (T1, T2, and T3) and its heating level (Ph) can be adjusted; at least one temperature sensor (ST) for sensing the predetermined temperature values (T1, T2, and T3) on the outer surface (FS) of the fixing roller; and a blowing airflow (AJ, AJ1-3) fed by a controllable cooling unit (CO) for cooling the outer surface of the fixing roller; said cooling unit (CO) having at least one blowing air unit (AT, AT1-3) in the form of a pipe and connected to a compressed air source (BL, AS), whereby the blowing air unit (BL, AS) is mounted in a stationary manner axially parallel to the fixing roller (FR) and radially at a distance from its outer surface (FS), and located, in relation to the supported direction (X) of the imaging medium (P) carrying the toner image in the direction of the airflow towards the fixing nip (N), at a distance from this fixing nip said at least one blowing air unit providing a focused and concentrated blowing airflow (AJ, AJ1-3) to create a cooling strip (SA, SA1-3) on the outer surface of the fixing roller, the width of the whole cooling strip generated from the cooling strip (CA, CA1-3) of the blowing air unit (AT, AT1-3) being a substantially equal or less than one-fourth of the outer surface of the fixing roller (FR), whereby its airflow level (Pc) can be controlled and adjusted by said control/adjustment unit (CU) acting upon the compressed air source (BL, AS), wherein a first predetermined temperature value (T1) of the fixing roller (FR) is generated and adjusted by the heating unit (H1) run at constant maximal heating level (Ph), and after reaching the first temperature value of the blowing airflow (AJ, AJ1-3) of the cooling unit (CO) driven by small to mid (0 to 50%) airflow level (Pc), it switches over from a first (W) to a second (A) operational state of the fixing unit, and a predetermined lower temperature value (T2) of the fixing roller (FR) at further constant heating level (Ph) is generated and adjusted into a third operational state (F) of the fixing unit by blowing airflow (AJ, AJ1-3), which is run at maximal (100%) to mid (about 50%) airflow level (Pc).