AUTOMATIC LIGHT CONTROL SYSTEM

• US 3,790,848 A
• Filed: 04/10/1972
• Issued: 02/05/1974
• Est. Priority Date: 04/10/1972
• Status: Expired due to Term

• Current Assignee: Thomas K.Y. Lai
• Original Assignee: Thomas K.Y. Lai
• Inventors: Lai, Thomas K. Y.
• Primary Examiner(s): Lawrence, James W.
• Assistant Examiner(s): Grigsby, T. N.
• Application Number:
  US05/242,351
• Time in Patent Office: 666 Days
• Field of Search: 315/155,159 250/209
• US Class Current: 315/155
• CPC Class Codes: H03K 17/292 in thyristor, unijunction transistor or programmable unijunction transistor switches
• CPC Class Codes: H05B 47/10 Controlling the light source

Abstract

Garage lights are automatically turned on by a photocell which is illuminated by automobile headlights. A timing circuit keeps the lights on for a predetermined period after automobile headlights are turned off. House current is stepped down, rectified and smoothed. Direct current is applied across a variable voltage divider. A starter which may be a push button, a headlight receiving photocell or a roll over switch supplies voltage to a mid point of the divider. Voltage at the mid point is reduced during daylight hours by an exterior photocell in a conductive condition. During darkness the exterior photocell'"'"''"'"'s high resistance as compared to the low resistance of a headlight actuated photocell creates a high mid point voltage. The high mid point voltage breaks down a zener diode, gating current to a capacitor and biasing an electronic switch for turning on the garage lights. When the voltage applied to the breakdown device falls, the gate turns off, and the capacitor slowly discharges through a resistor. A directional limiting device in the gate and cascaded transistors in the switch biasing connection prevent discharge of the capacitor except through the desired resistor. The electronic switch employs cascaded transistors for controlling the application of direct current to a reed relay. Power contacts of the relay complete a diac circuit, which biases on a triac, turning on the lights.

Claims

1. A lighting system comprising a power source, light means for illuminating a space, and control means for communicating the power source with the light means, the control means comprising a breakdown device having a first terminal and having a second terminal connected to ground, a first resistance connected between the first terminal and ground, resistance reducing means connected in parallel to the first resistance, an exterior photocell for sensing daylight conditions connected to the reducing means and for activating the reducing means, thereby maintaining a circuit through the breakdown device in the control means open during daylight conditions, a controller connected to the power source and to the first terminal for completing the circuit in the control means from the power source through the breakdown device when the controller is activated and when the exterior photocell is inactive during darkness, and switch means connected to the circuit and connected to the power source and to the light means for communicating the power source and the light means upon completion of the circuit in the control means.

2. The lighting system of claim 1 further comprising energy storage means connected to the circuit and energy drain means connected to the circuit in parallel to the energy storage means between the switch means and the second terminal of the breakdown device for maintaining operation of the circuit and the switch means while energy is stored in the storage means and for terminating operation of the circuit and switch means when energy is drained from the storage means.

3. The lighting system of claim 1 wherein the power source comprises a source of alternating current, and wherein the light means comprises electric lamps operable upon communicating with the power source, and wherein the control means comprises a power supply connected to the power source for converting the alternating current to direct current and a voltage divider connected to the power supply, wherein the exterior photocell is connected between a midpoint and ground in the voltage divider, and wherein the breakdown device is connected to the midpoint, whereby light impinging on the exterior photocell reduces voltage of the midpoint below a breakdown voltage, and whereby the exterior photocell presents a high resistance during darkness, and whereby the controller reduces resistance in the opposite portion of the voltage divider so that voltage of the midpoint is raised to exceed breakdown voltage of the breakdown device, and wherein the switch means comprises electronic switch means having a control terminal connected to the breakdown device and having power terminals connected between the power source and the light means whereby voltage at or above breakdown voltage passes through the breakdown device to the control terminal, operating the switch, completing the power terminals and communicating the power source and the light means.

4. A timed automatic lighting system for providing illumination during passage between automobile and house doorways comprising a power supply having a primary with terminals configured for connection to a household power source and having a secondary for reducing primary voltage, rectifier means connected to the secondary for producing direct current, a starting circuit connected to the rectifier and having a starter for passing varied current according to a condition of the starter, and shorting means connected to the starting circuit and to the rectifier for substantially shorting the starting circuit, the shorting means comprising a first resistance connected between the starter and ground, resistance reducing means connected in parallel to the first resistance, and an exterior photoresistor connected in the resistance reducing means for reducing resistance and shorting the starting circuit when the exterior photoresistor is illuminated by daylight, gating means comprising a breakdown device having a first terminal connected to the starting circuit for gating current above a predetermined voltage, timing means comprising a capacitor and resistor connected in parallel between ground and a second terminal of the breakdown device and thereby connected to the gating means for receiving current from the gating means, and a switch means connected to the timing means for closing when the timing means is on, transmission means connected to the switch means and having terminals for connection to a household power source and light producing means connected to the transmission means, whereby the light means are lighted when the switch means is closed.

5. The lighting system of claim 4 wherein the timing means capacitor and resistor, comprises storage means for storing energy from the gating means, and comprises discharge control means connected to the storage means for controlling discharge rate of the storage means upon interruption of gated energy, whereby the switch means is held on for a predetermined time.

6. The lighting system of claim 4 wherein the shorting means comprises a transistor having power terminals communicating with the starting circuit and with ground and wherein the external photoresistor is connected to a base of the transistor for turning the transistor on during daylight hours.

7. A lighting system comprising a source of alternating current, electric lamps operable upon communicating with the source for illuminating a space, a power supply connected to the power source for converting the alternating current to direct current, a voltage divider connected to the power supply, an exterior photocell connected between a midpoint and ground in the voltage diver, a breakdown device is connected to the midpoint, whereby light impinging on the exterior photocell reduces voltage of the midpoint below a breakdown voltage, and whereby the exterior photocell presents a high resistance during darkness, a controller connected between the midpoint and an opposite pole of the voltage divider, whereby the controller reduces resistance in the opposite portion of the voltage divider so that voltage of the midpoint is raised to exceed breakdown voltage of the breakdown device, an electronic switch means having a control terminal connected to the breakdown device and having power terminals connected between the power source and the lamps whereby voltage at or above breakdown voltage passes through the breakdown device to the control terminal, operating the switch, completing the power terminals and communicating the power source and the lamps, a capacitor connected to ground and to a point in the circuit between the control terminal of the switch means and the breakdown device for storing energy passing through the device and a discharging resistor connected in parallel to the capacitor for slowly discharging the capacitor, whereby upon discontinuance of operation of the controller, and hence discontinuance of the breakdown voltage and discontinuance of Current passing through the breakdown device, the capacitor maintains the control terminal at a voltage sufficient to hold the electronic switch means on for a period of time until the resistor discharges the capacitor to a voltage below an on voltage required by the control terminal.

8. The apparatus of claim 7 further comprising a filter connected across the power supply and parallel to the voltage divider, a current limiting resistor connected in series between the power supply and the voltage divider, and a zener diode connected in parallel to the filter, whereby voltages in excess of a breakdown voltage of the zener diode are grounded.

9. The lighting system of claim 7 wherein the circuit further comprises a reverse current preventing device inserted between the breakdown device and the capacitor for preventing discharge of the capacitor through the breakdown device, and wherein the electronic switch means further comprises a high input-resistance cascaded transistor device connected to the control terminal for preventing discharge of the capacitor through the control terminal.

10. A timed automatic lighting system for providing illumination during passage between automobile and house doorways comprising a power supply having a primary with terminals configured for connection to a household power source and having a secondary for reducing primary voltage, rectifier means connected to the secondary for producing direct current, a starting circuit connected to the rectifier having a starter comprising a penumatic pulse operated switch for passing varied current according to a condition of the starter, and shorting means connected to the starting circuit and to the rectifier for substantially shorting the starting circuit, gating means connected to the starting circuit above a predetermined voltage, timing means connected to the gating means for receiving current from the gating means, and switch means connected to the timing means for closing when the timing means is on, transmission means connected to the switch means and having terminals for connection to a household power source and light producing means connected to the transmission means, whereby the light means are lighted when the switch means is closed.

11. The lighting system of claim 10 wherein the pneumatic pulse operated switch comprises an air hose plugged at a distal end and connected to a nipple communicating with a base of a first cup, a second cup inverted upon the first cup and slidable thereon, and contacting means connected to the second cup, whereby the second cup is slid outward and the contacts are closed upon a compression of the air hose.

12. A timed automatic lighting system for providing illumination during passage between automobile and house doorways comprising a power supply having a primary with terminals configured for connection to a household power source and having a secondary for reducing primary voltage, rectifier means connected to the secondary for producing direct current, a starting circuit connected to the rectifier having a starter comprising a photocell and a variable resistor connected in series for passing varied current according to a condition of the starter, and shorting means connected to the starting circuit and to the rectifier for substantially shorting the starting circuit, gating means connected to the starting circuit above a predetermined voltage, timing means connected to the gating means for receiving current from the gating means, and switch means connected to the timing means for closing when the timing means is on, transmission means connected to the switch means and having terminals for connection to a household power source and light producing means connected to the transmission means, whereby the light means are lighted when the switch means is closed.

13. The lighting system of claim 12 further comprising a push button connected in parallel to the photocell and variable resistor.

14. A lighting system comprisIng a source of alternating current, electric lamps operable upon communicating with the source for illuminating a space, a power supply connected to the power source for converting the alternating current to direct current, a voltage divider connected to the power supply, an exterior photocell connected between a midpoint and ground in the voltage divider, a breakdown device is connected to the midpoint, whereby light impinging on the exterior photocell reduces voltage of the midpoint below a breakdown voltage, and whereby the exterior photocell presents a high resistance during darkness, a controller connected between the midpoint and an opposite pole of the voltage divider, whereby the controller reduces resistance in the opposite portion of the voltage divider so that voltage of the midpoint is raised to exceed breakdown voltage of the breakdown device, an electronic switch having a control terminal connected to the breakdown device, and having a reed relay, the reed relay having power contacts, a diac connected in series to the power contacts and to the power source, a triac having power terminals connected to the lamps and to the power source and having a control terminal connected to the diac for supplying power from the source to the lamps upon completion of the diac circuit by closing of the reed relay contacts.

15. A lighting system comprising a source of alternating current, electric lamps operable upon communicating with the source for illuminating a space, a power supply connected to the power source for converting the alternating current to direct current, a voltage divider connected to the power supply, an exterior photocell connected between a midpoint and ground in the voltage divider, a breakdown device is connected to the midpoint, whereby light impinging on the exterior photocell reduces voltage of the midpoint below a breakdown voltage, and whereby the exterior photocell presents a high resistance during darkness, a controller connected between the midpoint and an opposite pole of the voltage divider wherein the controller compr1ses a second photocell and a normally open push button connected in parallel whereby the controller reduces resistance in the opposite portion of the voltage divider so that voltage of the midpoint is raised to exceed breakdown voltage of the breakdown device.

16. A lighting system comprising a source of alternating current, electric lamps operable upon communicating with the source for illuminating a space, a power supply connected to the power source for converting the alternating current to direct current, a voltage divider connected to the power supply, an exterior photocell connected between a midpoint and ground in the voltage divider, a breakdown device is connected to the midpoint, whereby light impinging on the exterior photocell reduces voltage of the midpoint below a breakdown voltage, and whereby the exterior photocell presents a high resistance during darkness, a controller connected between the midpoint and an opposite pole of the voltage divider, wherein the controller comprises an air hose operated pneumatic roll over switch and a push button connected in parallel, whereby the controller reduces resistance in the opposite portion of the voltage divider so that voltage of the midpoint is raised to exceed breakdown voltage of the breakdown device.

17. A timed automatic lighting system for providing illumination during passage between automobile and house doorways comprising a power supply having a primary with terminals configured for connection to a household power source and having a secondary for reducing primary voltage, rectifier means connected to the secondary for producing direct current, a starting circuit connected to the rectifier having a starter for passing varied current according to a condition of the starter, and shorting means connected to the starting circuit and to the rectifier for substantially shorting the starting circuit, gating means connected to the starting circuit above a predeteRmined voltage, timing means connected to the gating means for receiving current from the gating means, the timing means comprising storage means for storing energy from the gating means, and discharge control means connected to the storage means for controlling discharge rate of the storage means upon interruption of gated energy, whereby the timing means is held on for a predetermined time after interruption of the gated energy, the discharge controlling means comprising a resistor connected in parallel to the storage means, a unidirectional device connected between the storage means and the gating means for preventing reverse flow of current through the gating means, and base connections to cascaded transistors for preventing flow of substantial current through base circuits of the transistors;

and switch means connected to the timing means for closing when the timing means is on, transmission means connected to the switch means and having terminals for connection to a household power source and light producing means connected to the transmission means, whereby the light means are lighted when the switch means is closed.

18. A timed automatic lighting system for providing illumination during passage between automobile and house doorways comprising a power supply having a primary with terminals configured for connection to a household power source and having a secondary for reducing primary voltage, rectifier means connected to the secondary for producing direct current, a starting circuit having a starter switch with normally open terminals, the starting circuit being connected to the rectifier for passing varied current according to a condition of the starter, the starting circuit comprising a capacitor connected to the terminals for storing current passing through the terminals, transistor mean having a base connected to the capacitor adjacent the terminals, for turning the transistor means on when the terminals are closed, and the transistor means having power terminals in the starting circuit;

and shorting means connected to the starting circuit and to the rectifier for substantially shorting the starting circuit, gating means connected to the starting circuit above a predetermined voltage, timing means connected to the gating means for receiving current from the gating means, and switch means connected to the timing means for closing when the timing means is on, transmission means connected to the switch means and having terminals for connection to a household power source and light producing means connected to the transmission means, whereby the light means are lighted when the switch means is closed.