Patents Assigned to Royce Thompson Limited
  • Patent number: 5977717
    Abstract: A lighting control system comprises a photosensor (12), a comparative circuit (16) and a logic switching circuit (26). The photosensor (12) produces an output (VP) which is a function of the light intensity level, and the comparative circuit (16) compares the output (VP) from the photosensor (12) with a number of preset levels (V1 to V6) in order to produce a logic output which controls the switching of the logic switching circuit (26) between four states: daylight (32), dusk (34), night (36) and dawn (38). At dusk, when the light intensity falls below a predetermined value (L2) the light is switched on. If the light intensity level then improves the light will not, however, switch off again until the light intensity rises above another higher predetermined level (L6). Similarly at dawn, the light will switch off when the light intensity rises above a predetermined value (L4) and then only switch on again if the light intensity falls below a different, lower predetermined value (L5).
    Type: Grant
    Filed: May 20, 1998
    Date of Patent: November 2, 1999
    Assignee: Royce Thompson Limited
    Inventor: Michael John Dean