Control unit for occupancy sensor switching of high efficiency lighting

• US 5,473,202 A
• Filed: 06/05/1992
• Issued: 12/05/1995
• Est. Priority Date: 06/05/1992
• Status: Expired due to Term

• Current Assignee: ABL IP Holding LLC (Acuity Brands, Inc.)
• Original Assignee: Brian Platner
• Inventors: Mudge, Philip H., Platner, Brian
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): GANJIAN, PETER
• Application Number:
  US07/894,091
• Time in Patent Office: 1,278 Days
• Field of Search: 307/116, 307/117, 340/500, 361/173, 361/176, 361/177, 361/2-13, 323/235, 323/236, 323/319
• US Class Current: 307/116
• CPC Class Codes: H01H 2009/545 comprising a parallel semiconductor switch being fired optically, e.g. using a photocoupler,
• CPC Class Codes: H01H 9/542 Contacts shunted by static switch means
• CPC Class Codes: H03K 17/79 controlling bipolar semiconductor switches with more than two PN-junctions, or more than three electrodes, or more than one electrode connected to the same conductivity region
• CPC Class Codes: H03K 17/945 Proximity switches H03K17/96 takes precedence
• CPC Class Codes: H03K 2217/0036 Means reducing energy consumption
• CPC Class Codes: H05B 47/115 by determining the presence or movement of objects or living beings
• CPC Class Codes: H05B 47/14 by determining electrical parameters of the light source
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A control unit for switching AC powered high efficiency lighting in response to a signal from an occupancy sensor. The lighting is switched by a hybrid mechanical relay/semiconductor switch. The semiconductor switch is connected in parallel with the relay switch contacts to protect them and is controlled by a noise-insensitive zero voltage crossing detector circuit which switches the semiconductor switch only at the zero crossings of the AC power. The semiconductor switch is preferably turned on by a pulse forming circuit only for a brief period of time spanning the time when the relay is switching.

Claims

1. A control unit adapted trot switching an AC powered high efficiency lighting load in response to an occupancy sensor comprising:

an on/off control circuit for controlling a relay control circuit and a noise-insensitive semiconductor switch control circuit, the on/off control circuit being adapted to receive signals from an occupancy sensor, the control circuit providing an on/off control signal having an on state indicating the load should be turned on when occupancy is sensed and an off state indicating the load should be turned off thereafter;

the relay control circuit being directly responsive to the on/off control signal and not responsive to the semiconductor switch control circuit and including a delay means for delaying the on state and the off state of the on/off control signal for a delay time;

a relay having an actuator connected to the relay control circuit which actuates relay switch contacts upon receipt of the delayed on/off control signal, the relay switch contacts being adapted to carry AC load current of the load and being movable from an open to a closed position during a relay closing time and movable from a closed to an open position during a relay opening time;

the delay time plus the shorter of the relay closing time or the relay opening time being greater than the time between successive zero crossings of the AC power;

the noise-insensitive semiconductor switch control circuit having an output for controlling a semiconductor switch and a zero voltage crossing detector that switches the output of thee semiconductor switch control circuit only at the zero crossings of the AC power responsive to the on/off control signal;

a semiconductor switch which switches in response to the noise insensitive semiconductor control circuit immediately, the semiconductor switch being adapted to carry the AC load current and having switch leads connected in parallel across the relay switch contacts; and

the control unit switching the relay based on the time of the on/off control signal as delayed by the relay control circuit and not based on the time of the zero crossings of the AC power detected by the zero voltage crossing detector in the noise insensitive semiconductor control circuit.

2. A control unit according to claim 1 further comprising a pulse forming circuit responsive to the on/off control signal to generate a pulse for each on-to-off and each off-to-on transition of the control signal, and wherein the noise-insensitive semiconductor switch control circuit is responsive to the pulses from the pulse forming circuit.

3. A control unit according to claim 2 wherein the pulses have a duration which is greater than the sum of the delay time plus the longer of the relay opening time or the relay closing time.

4. A control unit according to claim 3 wherein the pulse generated at the on-to-off transition has a duration which is greater than the sum of the delay time plus the relay opening time, and the pulse generated at the off-to-on transition has a duration which is greater than the sum of the delay time plus the relay closing time.

5. A control unit according to claim 1 wherein the delay time is longer than the time between successive zero crossings of the AC power.

6. A control unit according to claim 1 wherein the on/off control circuit includes a timer to turn the control signal off a preset interval after the control signal is turned on, the control signal being turned on and the timer being reset when the occupancy sensor senses occupancy.

7. A control unit according to claim 1 wherein the occupancy sensor comprises an infrared detector.

8. A control unit according to claim 1 wherein the zero voltage crossing detector is optically isolated between an input responsive to the on/off control signal and an output providing the output signal.

9. A control unit according to claim 1 wherein the semiconductor switch comprises a triac.

10. A control unit according to claim 1 wherein the semiconductor switch comprises a pair of SCR'"'"'s.

11. A control unit according to claim 1 wherein the semiconductor switch comprises an alternistor.

12. A control unit according to claim 1 wherein the occupancy sensor comprises an ultrasonic detector.

13. A control system for switching electronically ballasted AC powered high efficiency fluorescent lights comprising:

an occupancy sensor producing an occupancy signal whenever the presence of a person in a room containing electronically ballasted AC powered high efficiency fluorescent lights is sensed;

an on/off control circuit connected to the occupancy sensor and responsive to the occupancy signal, the control circuit providing an on/off control signal at an output thereof, the on/off control signal having an on state indicating the load should be turned on when occupancy is sensed and an off state indicating the load should be turned off thereafter, the on/off control circuit further including a timer to switch the on/off control signal to the off state a preset interval after the control signal is turned to the on state, the control signal being turned to the on state and the timer being reset each time the occupancy sensor senses the presence of a person in the room; and

a hybrid switch specially adapt to be noise insensitive and to reliably switch electronically ballasted AC powered high efficiency fluorescent lights, the hybrid switch including;

a relay control circuit responsive to the on/off control signal and including a delay means for delaying the on state and the off state of the on/off control signal for a delay time;

a relay having an actuator connected to the relay control circuit which actuates relay switch contacts upon receipt of the delayed on/off control signal, the relay switch contacts moving between an open and a closed position and being adapted to carry AC load current of the electronically ballasted high efficiency fluorescent lighting load when in the closed position;

a noise-insensitive semiconductor switch control circuit specially adapted for controlling a semiconductor switch in a noisy electrical environment generated by the electronically ballasted AC powered high efficiency fluorescent lighting load, the semiconductor switch control circuit including a noise-insensitive zero voltage crossing detector that switches the output of the semiconductor switch control circuit at the zero crossing of the AC power responsive to the on/off control signal and means for controlling the semiconductor switch to turn the semiconductor switch on for a short duration surrounding the time when the relay is opening or closing and to turn the semiconductor switch off for long durations when the relay is remaining in the open or closed position; and

the control system switching the relay based on the time of the on/off control signal as delayed by the relay control circuit and not based on the time of the zero crossings of the AC power detected by the zero voltage crossing detector in the noise insensitive semiconductor control circuit.

14. A control unit according to claim 13 wherein the means for controlling the semiconductor switch to turn the semiconductor switch on for a short duration surrounding the time when the relay is opening or closing and to turn the semiconductor switch off for long durations when the relay is remaining in the open or closed position comprises a pulse forming circuit responsive to the on/off control signal to generate a pulse for each on-to-off and each off-to-on transition of the control signal.

15. A control unit according to claim 14 wherein the pulses have a duration which is greater than the sum of the delay time of the delay means in the relay control circuit plus the longer of the relay opening time, defined as the time for the relay to move from the closed to the open position, and the relay closing time, defined as the time for the relay to move from the open to the closed position.

16. A method for saving energy by automatically turning on an electronically ballasted AC powered high efficiency fluorescent lighting load installed in a room whenever the room is occupied and automatically turning off the lighting load whenever the room is unoccupied, comprising:

sensing the presence of a person in a room containing electronically ballasted AC powered high efficiency fluorescent lights with an occupancy sensor producing an occupancy signal whenever occupancy is sensed in the room;

generating an on/off control signal in an on/off control circuit responsive to the occupancy signal from the occupancy sensor, the on/off control signal being generated in an on state indicating the load should be turned on when occupancy is sensed;

timing in a timer for a preset interval after the on/off control signal is turned to the on state and turning the on/off control signal to the off state indicating the load should be turned off;

resetting the timer to the beginning of the preset interval each time the occupancy sensor senses the presence of a person in the room

switching the electronically ballasted AC powered high efficiency fluorescent lights on and off with a hybrid switch specially adapted to be noise insensitive, the lights being switched on by the hybrid switch whenever the on/off control signal is in the on state and switching the lights off whenever the on/off control signal is in the off state, the hybrid switch including;

a relay control circuit responsive to the on/off control signal and including a delay means for delaying the on state and the off state of the on/off control signal for a delay time;

a relay having an actuator connected to the relay control circuit which actuates relay switch contacts upon receipt of the delayed on/off control signal, the relay switch contacts being adapted to carry AC lead current of the electronically ballasted high efficiency fluorescent lighting lead;

a noise-insensitive semiconductor switch control circuit specially adapted for controlling a semiconductor switch in a noisy electrical environment generated by the electronically ballasted AC powered high efficiency fluorescent lighting lead, the semiconductor switch control circuit including a noise-insensitive zero voltage crossing detector that switches the output of the semiconductor switch control circuit only at the zero crossings of the AC power responsive to the on/off control signal;

a semiconductor switch which switches in response to the noise-insensitive semiconductor control circuit, the semiconductor switch being adapted to carry the AC lead current of the electronically ballasted high efficiency fluorescent lighting lead and having switch leads connected in parallel across the relay switch contacts; and

the hybrid switch switching the relay based on the time of the on/off control signal as delayed by the relay control circuit and not based on the time of the zero crossings of the AC power detected by the zero voltage crossing detector in the noise insensitive semiconductor switch control circuit.

17. A method for saving energy according to claim 16 further including the steps of:

turning on the semiconductor switch only for a short duration surrounding the time when the relay is opening or closing; and

turning off the semiconductor switch for long durations when the relay remains for long durations in the open or closed position.