AUTOMATIC ILLUMINATION CONTROL SYSTEM RESPONSIVE TO TOTAL ILLUMINATION

• US 3,609,451 A
• Filed: 02/16/1968
• Issued: 09/28/1971
• Est. Priority Date: 02/16/1968
• Status: Expired due to Term

• Current Assignee: Peter J. Zanini Jr, Raymond G. Edgerly Jr
• Original Assignee: Peter J. Zanini Jr, Raymond G. Edgerly Jr
• Inventors: Edgerly, Raymond G. Jr., Zanini, Peter J. Jr.
• Primary Examiner(s): Segal, Robert
• Application Number:
  US04/706,128
• Time in Patent Office: 1,320 Days
• Field of Search: 315/151,159,158 250/205,210
• US Class Current: 315/151
• CPC Class Codes: H05B 47/10 Controlling the light source

Abstract

A system for sensing the total amount of illumination in an area from both uncontrolled and controlled sources and automatically adjusting the amount of artificial light supplied to maintain a substantially constant value of total illumination and in which the system enables the relative adjusting of the importance of the uncontrolled light to the controlled light that is being sensed to reduce the effect of abnormal conditions caused by the uncontrolled light on the system.

Claims

1. An automatic illumination control system for maintaining substantially constant the total illumination in an area wherein the illumination is derived from controlled and uncontrolled sources comprising a source of alternating power connected to said controlled source by a common terminal and a tap variable in position across said source for selecting a voltage corresponding to a predetermined total illumination level, a rectifier connected to said tap and common terminal to have a unidirectional voltage on its output leads directly related to the voltage between said variable tap and common terminal, a resistor having an adjustable tap connected across the output leads of said rectifier, a photocell positioned in the area to sense the total illumination therein, said adjustable tap being at the junction of two legs of a bridge circuit, one of said legs including said photocell, said bridge circuit further having intermediate junctions respectively connected between the positive and negative terminals of a unidirectional voltage source, and an opposite junction, the photocell sensing signal between said junction and said opposite junction being in opposition to the voltage at one of said rectifier output leads, said signal being the algebraic sum of the sensing signal and the adjusted voltage from said rectifier means, and means responsive to said signal for controlling the position of said variable tap, said means being connected between said junction and said one of said rectifier output leads.

2. An automatic illumination control system for maintaining substantially constant the total illumination in an area wherein the illumination is derived from controlled and uncontrolled sources comprising a source of alternating power connected to said controlled source by a common terminal and a tap variable in position across said source for selecting a voltage corresponding to a predetermined total illumination level, a rectifier connected to said tap and common terminal to have a unidirectional voltage on its output leads directly related to the voltage between said variable tap and common terminal, a variable resistor in series with a light bulb connected across the output leads of said rectifier, a photocell positioned in the area to sense the total illumination therein, said photocell being included in the leg of a bridge circuit having two pairs of opposite junctions, means for connecting the junctions of one pair respectively between the positive and negative terminals of a unidirectional voltage source, and means connEcted to the junctions of the other pair for deriving a control voltage therefrom and for controlling the position of said variable tap in response thereto, and means for locating the light bulb adjacent the photocell to have its light directed toward the photocell together with the total illumination in the area and in which the photocell has a small sensing area that is directionally responsive to light rays perpendicular thereto and in which diffusing means of translucent material in the form of a hemisphere is positioned about the sensing area of the photocell, said control voltage having a magnitude and polarity determined by variations of said total illumination from said predetermined total illumination level, whereby said variable tap is positioned to compensate for such variations.