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US 4,233,545 AGranted
Automatic lighting control system
AssigneeNone recorded
InventorsLee R. Webster, Gary J. Woods
Life of this patent
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AssigneeNone recorded
InventorsLee R. Webster, Gary J. Woods
Estimating the term…
This invention relates to an automatic lighting control system which employs a photosensitive detector in one leg of a bridge circuit for sensing the total effective level of both the natural and artificial illumination within an interior space. The unbalanced output of the bridge is fed into a pair of differential comparators for deriving a digital error signal representative of the level of illumination falling outside an acceptable range. A digital error signal is loaded into an intermediate shift register responsive to a clock signal. If an error signal of the type requiring a change in illumination is present, then a subsequent clock pulse will command a shift register to add or interrupt power to one or more lighting modules which supply artificial illumination to the interior space.
An illumination control apparatus for controlling the flow of electrical energy from a source thereof to a plurality of lighting modules for supplementing natural illumination so as to maintain a desired level of total illumination within an interior space, said illumination control apparatus comprising in combination:
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
Systems of lighting devices, not provided for in main groups f21s4/00 -
Activated by means of a sensor, e.g. motion or photodetectors: the sensor sensing the level of ambient illumination, e.g. dawn or dusk sensors
The light-intensity of the source: by measuring the incident light
In response to determined parameters: by determining the brightness or colour temperature of ambient light
Term ended 18 Sep 1998 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
I. Field of the Invention
The present invention relates to a lighting control system for controlling the intensity of artificial illumination in order to automatically supplement natural illumination present in an area of concern. The total level of illumination is generally maintained constant, and the level of this constant illumination may be adjusted.
II. Description of the Prior Art
Other objects, features and advantages of the present invention will be apparent through a study of the written description and the drawings in which:
FIG. 1 is a perspective illustration of an interior room having an automatic lighting control system in accordance with the present invention installed for regulating the artificial illumination so as to supplement the illumination provided by the natural sunlight.
FIG. 2 illustrates a schematic diagram of bridge and control circuitry utilized in the first preferred embodiment of the present invention.
A first preferred embodiment of an electronic automatic lighting control system in accordance with the teachings of the present invention is shown generally in FIG. 1. The system is designed to be employed in a room having external windows through which natural sunlight may pass. The purpose of this system is to automatically supplement the variable illumination from the sun with artificial illumination, such as from incandescent or fluorescent light sources.
As illustrated in FIG. 1, a photosensitive detector, shown generally as 10, is mounted at a location within the interior section of the room so as to view a relatively wide angle section of the room. The photosensitive detector 10 will sense the combination of the natural sunlight passing through the windows and the artificial illumination from the fluorescent lights 11, 12, 13, 14, 15, 16, etc. A signal representative of the total level of both artificial and natural illumination present within the room will be transmitted through a circuit conductor 18 to bridge an error detecting logic circuitry 20, which is typically mounted adjacent to the door leading into the room within the junction box formerly provided for conventional on/off light control switches.
The commands derived from the bridge and logic circuitry 20 are transmitted through the conductor 19 to an additional portion of the logic control system 20a which actuates, through conductor 19a, the appropriate power controllers 21, 22, 23, 24, 25, 26 and 27 which are typically mounted adjacent to corresponding ones of the fluorescent lighting modules 11, 12, 13, 14, 15, 16 and 17 for controlling the flow of electrical energy thereto. In this manner the error detecting and logic control systems 20 and 20a can activate or deactivate lighting modules so as to maintain a specified constant level of illumination within the interior space, regardless of any variation in or complete absence of natural illumination from the sun.