摘要 |
<p>The refrigerator unit includes a light sensor (25) with an evaluation and control circuit (21) connected to it. Defrosting of the refrigerator is controlled from a light signal received by the sensor. The signal is evaluated in such a way that ambient night illumination conditions can be detected, in which case, defrosting is initiated. In making the determination, room lighting is detected and compared with a threshold. The rate of variation or a differential value of the lighting is examined, to determine whether a threshold is, or is not exceeded. The defrosting process is controlled in accordance with other variables. The variation rate in the light signal is evaluated. It is examined whether a differential value exceeds a threshold. A frequency filter included, has a passband matched with frequencies associated with fluorescent lighting tube emissions, i.e. 50 Hz, 60 Hz, 100 Hz or 120 Hz. Exceptional lighting conditions are detected using a day/night rhythm detection method, when determining whether to initiate defrosting. Similarly, a weekday rhythm method is used. A predetermined time delay obtained from a multiplier and a unit of delay is taken into account. A stored defrosting interval plan is invoked. The sensor looks upward or at an angle to the vertical. The defrosting equipment (19) also de-ices the refrigerator evaporator. An independent claim is included for the corresponding method of control.</p> |