Light and chime control system

[57] ABSTRACT

A daylight sensor and a headlight sensor are connected in a variable voltage divider. When darkness turns the daylight sensor off and headlights turn a sensor on, a potential is provided to a voltage gate which is sufficient to break down a zener diode and gate current to a timer circuit. A diode in the voltage gate prevents reverse flow of current from a timer.

A timer circuit contains a capacitor and resistor which discharges the capacitor. When the voltage is gated to the timer circuit and during the time that capacitor maintains a sufficient potential, a light switch is held on. A triac in the light switch control the lights.

Approximately 3 seconds after the capacitor in the timer is charged to its potential, a transistor is switched on, placing a ground potential to the midpoint of the voltage divider to cut off the gate voltage.

A chime operator is activated by sampling the potential from the variable voltage divider to slowly ring a door chime as an automobile is sensed. House and garage lights are lighted automatically a short time after a doorbell is rung at night to suggest a human response to the doorbell.

Claims, 6 Drawing Figures

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LIGHT AND CHIME CONTROL SYSTEM

This application is a continuation-in-part of patent application Ser. No. 242,351 now U.S. Pat. No. 3,790,848 filed Apr. 10, 1972 by Thomas K. Y. Lai for Automatic Light Control System.

BACKGROUND OF THE INVENTION

SUMMARY OF THE INVENTION

The automatic light control system is designed to provide home owner with safety, convenient and security within a garage or passageways or residences with minimum investment lasting a lifetime.

This solid state device is used for controlling and providing temporary lighting in darkened areas usually outside a house or apartment. Lights controlled by this system are usually those lights within a garage, those within a passageway, or those between a parking space and residence, or those placed exteriorly near the front door or inside lights.

The system is designed to operate in any house, garage or carport. Pneumatic switches are provided for homes with driveways, to turn on lights to ring door chimes when vehicles enter the area.

The operation of this system is automatically turned off during the daylight hours.

Parameters of system operation are described as follows:

Power Requirement: 117 volts AC, 60 Hertz, Fuse for half amps.

Circuit Power Supply: Regulated 11.8 volts DC.

Circuit DC Current Drain:

Daylight Hours — approximately 30 MA.

Night Hours — STAND BY less than 5 MA., OPERATING — approximately 60 MA.

Load: 450 watts maximum, incondescent lamps. Time Delay: 4 minutes and 9 minutes.

Condition Held System Inoperative: Daylight hours — hazy, overcast, dawn to dusk.

Light Starting Requirement:

1. 470 ohms control element at voltage divider circuit between midpoint and positive line.

2. three second of exposure of 100 foot-candle illumination on interior photocell.

Self Adjust Sensor Circuit:

Interior photocell PCI becomes de-sensitized to 60 foot-candle illumination in three seconds after the light is started. The interior photocell automatically restores to maximum sensitivity when the area is darkened.

The embodiments of this device take two forms, permanent installation or plug-in types. The system comprises electronic circuitry which is enclosed in the main chassis box with two terminal blocks. One terminal block is a low voltage block to which the remote switching or starting elements are connected, for example, a push-to-light switch near a doorway for starting a system as one leaves the house. A headlight receiving photocell is employed to switch on lights as the automobile approachs the area. A pneumatic switch may be substituted for the photocell sensor in some cases, such as in drive-through carports where no wall is available for mounting of an interior photocell. A daylight sensor photocell is mounted on an exterior of a building to prevention operation of the system during the daylight hours. A chime operator is connected to the system to ring the door chime.

A daylight sensor and a headlight sensor are connected in a variable voltage divider. When darkness turns the daylight sensor off and headlights turn a sensor on, a potential is provided to a voltage gate which is sufficient to break down a zener diode and gate current to a timer circuit. A diode in the voltage gate prevents reverse flow of current from a timer.

A timer circuit contains a capacitor and resistor which discharges the capacitor. When the voltage is gated to the timer circuit and during the time that capacitor maintains a sufficient potential, a light switch is held on. A triac in the light switch controls the lights.

Approximately 3 seconds after the capacitor in the timer is charged to its potential, a transistor is switched on, placing a ground potential to the midpoint of the voltage divider to cut off the gate voltage.

A chime operator is activated by sampling the potential from the variable voltage divider to slowly ring a door chime as an automobile is sensed. House and garage lights are lighted automatically a short time after a doorbell is rung at night to suggest a human response to the doorbell.

A power supply transmits power to the light switch and also provides 11.8 volt DC to the circuit.

DETAILED DESCRIPTION OF THE DRAWINGS

Throughout the drawings, like elements are referred to by like numerals.

FIG. 1 generally indicates the light control system of a preferred embodiment of the present invention. Electric lights 2 represent a lighting circuit which is controlled by the automatic device of the present invention. Plug 4 is representative of a connection for a power source. Box 6 contains the electronic circuits of the present invention and terminal boards.

Photocell 8 is mounted on an exterior of a building, for example, a garage to prevent operation of the system during daylight hours in one embodiment. Photocells 10 are mounted within a garage to detect headlights of cars for starting the system when a car is parked in a garage. In a two-car garage, photocells 10 may be mounted to detect headlights from either car. Photocells 10 may be used with adjustable circuits to detect back up lights when automobiles are backed into a garage.

In some cases, such as in drive-through carports, no wall is available for mounting of an interior photocell. A pneumatic switch may be substituted for photocells 10. A closed air hose supplies a pulse of air to a switch as an automobile crosses the hose. It is convenient to mount a push button starter adjacent a pedestrian entry to the garage. Where more than one entry to a garage is commonly used in darkness hours, two or more push buttons may be connected in parallel.

As shown schematically in FIG. 2, exterior photocell 8 and interior photocell 10 are connected in a variable voltage divider 20. When darkness turns photocell 8 off, and headlights turn photocell 10 on, a potential is provided to voltage gate 22 which is sufficient to breakdown device 24 and gate current to timer circuit 30. Unidirectional device 26 in gate 22 prevents reverse flow of current from timer 30.

Timer circuit 30 contains a capacitor 32 and a resistance 34 which discharges the capacitor. When the potential is gated to the timer circuit 30, and during the time that capacitor 32 maintains a sufficient potential, light switch 36 is held on. Triac 38 is schematically

3,886,352 shown within the light switch 36 for controlling lamp 2.

Power supply 40 receives power from source 4, transmits the power to the light switch 36, and reduces and rectifies current which it supplies to the variable voltage divider, the gate and the timer circuit. 5

A three seconds cut off SO with a transistor 52 is connected to gate 22 and voltage divider 20 to desensitize the interior photocell 8 to illumination after the system has been on for 3 seconds.

In FIG. 3 a low voltage terminal board generally indi- 10 cated by TB1 has connections A through G, which are found also in the upper part of the figure. High voltage terminal board TB2 has connections A, B and C which also are shown in the upper part of the drawing as, for example, TB2-A. Terminals A and B on the high volt- 15 age board are connected to lamps 2, and terminals B and C are connected to a voltage source which is shown as a plug 4. In systems which are intended for use in new constructions, lamps 2 generally indicate the basic garage lights, lights within a house and lights near 20 doors. Source 4 is wired directly to the roughed in electrical wiring. In add on systems a plug 4 and power lines are supplied. Lamps 2 may be the existing lamps, or lamps may be provided with a kit.

On the low voltage terminal board TB1, contacts A 25 and B receive push button 16. Terminals C and D receive internal photocell 10 or a roll over switch, or both may be connected in parallel to TB1 terminals C and D. Terminals E and F receive low voltage wiring from the external photocell 8. Terminal G is connected to ³⁰ground.

Referring to the main circuit in FIG. 3, voltage is supplied at source 4. A fuse 42 protects the circuit against voltage surges, which may be caused externally or by a short circuit in the system. Household current is ap- ³⁵plied through fuse 42 to primary 44 of transformer 46. Secondary 48 reduces the voltage to approximately 12 volts AC. A bridge rectifier generally indicated by the numeral 1 and comprising diodes 3, 5, 7 and 9 changes the low AC voltage to low DC voltage. Capacitor 12 filters AC components and smooths the output of the rectifier. Current limiting resistor 14 and capacitor 18 bias transistor 17 on to supply current flow through the DC electronic components. Zener diode 19 breaks down at excessive voltage effectively shorting capacitor 18, and turning off transistor 17, insuring that voltage between ground 27 positive power line 29 does not exceed a predetermined maximum.

In the variable voltage divider 20, photocells 8 and 10 may have dark resistances of about 5,000 ohms, or more, which are reduced to about 500 ohms when illuminated. When photocell 8 is at a low resistance value, the voltage drops across resistances 58, photocell 8 and resistance 59 cause voltage across resistance 59 suffi- ₅₅cient to bias transistor 54 on. Transistor 54 and resistor 53 drop connector 28 to a level sufficiently low to prevent operation of the voltage gate 22.

15K ohm resistor 55 is connected in parallel to the path including resistor 53 and transistor 54 in the lower portion of divider 20 so that the combined resistance of resistor 53 and resistor 55 is below 500 ohms when external photocell 8 is illuminated during daylight hours. In daylight conditions, the potential of midpoint 28 is thus reduced toward ground potential. ₆₅

In the upper portion of the divider 20, light cell 10 is connected in series with variable resistor 56, which has a capacity of about 25K ohms. Adjustment of resistor is made to bring the mid point 28 to a potential above the breakdown voltage of the breakdown device 24 in gate 22. When 12 volts are imposed across lines 27 and 29, resistor 56 may be adjusted so that when photocell 10 is illuminated by headlights during darkness hours, mid point 28 is brought to a potential slightly above a breakdown voltage of 6.8 volts. Correctly adjusting resistor 56 according to the fixed position of photocell 10 insures correct operation of the automatic system and insures against starting of the system by spurious illumination of photocell 10.

Photocell 10 may be replaced by an impulse switch or other suitable switch with a series connected resistance.

For convenience, one or more push buttons 16 may be provided at entrances to a garage. Preferably the push buttons are connected in series with a resistor 57, which may have a value of about 470 ohms.

During daylight hours, the low resistance of photocell 8 and resistor 53 and the parallel resistor 55 will always keep mid point 28 below the level of breakdown voltage required by breakdown device 24. When photocell 8 imposes its high darkness resistance, the potential of mid point 28 is raised above the breakdown voltage by reducing resistance in photocell 10 or by completing any of the switches.

Gate 22 contains breakdown device 24 which is preferably a zener diode. When voltage at midpoint 28 exceeds breakdown voltage, zener diode 24 conducts, supplying current to capacitor 32 and to timer 30 and to electronic switch 36. Storage capacitor 32 is charged immediately upon application of voltage to the timer circuit. Resistors 33 and 34 discharge voltage from capacitor 32 after the applied voltage has been discontinued. The rate at which resistors 33 and 34 discharge voltage from capacitor 32 controls the period of timer 30. Discharge of capacitor 32 through voltage divider 20 is prevented by unidirectional element 26, which is a diode. Discharge of the timer through the light switch 36 is prevented by a high input impedence device.

As an example, the capacitor 32 may have a value of 500 microfarads. Resistor 34 may have a value of from about 150 to about 2 megaohms.

Cutoff 50 includes a transistor 52 which is biased on by capacitor 51 in about three seconds after sufficient voltage is supplied through resistor 33 from zener diode 24 and from capacitor 32. Transistor 52 has an effect similar to transistor 54 in dropping the level of midpoint 28 to a value insufficient to break down zener diode 24 so that lights 2 may not raise the level of midpoint 28 by reducing the resistance of photocell 10. Cutoff 50 in effect desensitizes interior photocell 10 or renders its effect operative to raise the level of midpoint 28. Capacitor 51 maintains the on bias on transistor 52 until it discharges sufficiently through resistor 34, which is after capacitor 32 has discharged sufficiently to turn off swithc 36.

The function of the resistors 66, 67 and 69 and of the cascaded transistors 68 and 68' is to forward bias the light switch 36 while preventing substantial discharge of capacitor 32.

When transistor 68' is biased on by voltage from the timer section 30, DC power is supplied to reed relay 63 via current limiting resistor 65. Power terminals 70 and 71 of reed relay 63 close, completing the AC circuit to diac 60. Capacitor 61 and resistor 62 cooperate as an AC voltage divider so that the appropriate potential is

3,886,352 applied via diac 60 to the biasing terminal of triac 38. Power terminals of triac 38 complete the circuit between power source 4 and lights. 2.

As shown in FIG. 3, diode 64 protects the transistor 68' from sudden surges when the field collapses in the coil of relay 63. At the same time, diode 64 keeps the relay polarized.

In summary, FIG. 3 is a schematic diagram of the main circuit. 117 volts AC is applied across Terminal Block TB2 on Terminal B and C. Fuse 42 protects the circuit against the damage whenever short circuit or voltage surge occurs. The AC voltage is then fed to step down Transformer 46. The secondary of 48 develops a lower AC voltage, which is rectified by a full wave bridge rectifier 3, 5, 7, and 9. The rectified DC voltage output is filtered by capacitor 12 and is coupled to the collector of transistor 17 and to the base of 17 through resistance 14. 12 volt zener diode 19 regulates the base bias voltage, keeping the emitter voltage at constant 1 1.8 volts.

During daylight hours, both photocells 8 and 10 resistances drop to approximate 450 ohms. A base bias develops across photocell 8, and resistor 59 switches on transistor 54, placing a ground potential on the collector end of resistor 53. Resistor 53 and resistor 55 are electrically connected in parallel, and their total resistances are low, as compared to 400 ohms of photocell 10 resistance. The voltage at the midpoint 28 is kept below the break down level of zener diode 24.

When night falls, the resistance of PCI and PC2 rise beyond 5,000 ohms. Transistor 54 cuts off the ground path of resistor 53. The midpoint voltage at 28 still is below the zener diode 24 break down level, because resistance of photocell 10 is high as compared with resistor 55.

When an automobile enters the premise, its headlights strike the sensor photocell 10. The photocell resistance suddenly drops to 500 ohms. Voltage a midpoint 28 rises above 10 volts of which cause zener 40 diode 24 to break down. A DC current is induced through diode 26, charging capacitor 32. Transistor 68 is turned on by the voltage which develops across base resistor 67 by capacitor 32. The emitter voltage across resistor 66 switches on transistor 68', placing a ground 45 potential to relay 63 and energizing it.

1 7 volts AC from terminal block TB2 on terminals V and C applies to resistor 62 and capacitor 61 when closing relay contacts 70 and 71. The diac 60 which receives AC voltage from resistor 62 and capacitor 61 ⁵⁰transmits trigger pulses to the gate of triac 36. Incondescent lamp 2 is turned on by the triac.

Approximately three seconds following the sudden rise of potential in capacitor 32, a voltage is developed across resistors 33 and 34, charging capacitor 51 to a potential that sufficiently forward biases transistor 52. Once again resistor 53 is electrically connected in parallel with resistor 55 by the collector-emitter path of transistor 52 to the ground. The midpoint voltage immediately drops below the zener gated level. That cuts off the charging current to capacitor 32. Capacitor 32 begins to discharge through resistors 33 and 34. The voltage in 32 slowly drops to a level that turns off transistors 68 and 68' and relay 63 and then the light switching circuit. The period which takes capacitor 32 to discharge to a cutoff level is approximately 9 minutes. The time delay could be reduced to approxi6 mately 4 minutes by adding a discharge path with another resistor connected in parallel to capacitor 32.

Terminal block TB1 is used for interconnecting low voltage switch elements to the main circuit.

Terminal block TB2 provide connections between the light switch triac 36 and its load. TB2 also supplies AC power to the main circuit.

When the push to light switch 16 is depressed, it applies 11.8 volts DC to 470 ohms resistor 51. The mid¹⁰ point voltage at 28 rises above the gated level of zener diode 24.

A door chime operator generally referred to by the numeral 90 is shown in FIG. 4.

Two conditions activate the door chime; when vehicle head lights are detected by PCI photocell, and when automobile rolls over the pneumatic switch hose.

This system utilizes the same two or more tone door chime as in a house. The vehicle entering a garage immediately activates the door chime to produce a ding tone first and then three seconds later a dong tone. The reason for the dragging tone is to enable homeowner to distinguish the ringing sound of an incoming car and that of a person at the door.

The contacts 93 and 94 of the chime relay 92 are normally open. Referring to FIG. 4, they are connected in parallel to the door chime button switch 79 by a pair of wires from TB3 terminal board terminals M and L.

When vehicle head lights are detected by photocell ³⁰ 10 in the main chassis circuit in FIG. 3 the resistance of the photocell suddenly drops, causing a positive 11.8 volts DC to appear at TB1 terminal A through resistor 56. This voltage is transferred from terminal block TB1 to chime operator box TB3 terminal 4, the voltage causes the 5.6 volt zener diode 88 to break down. Capacitor 102 picks up this positive pulse and couples it to the base of the transistor 91. This pulse energizes the relay 92. Relay contacts 93 and 94 complete the current path of the door chime, which rings its first tone ding. At approximately three seconds later, the positive voltage in terminal J of TB3 drops below the zener diode 88 break down level by the action of transistor 52 in the main chassis. Transistor 91, losing its base bias voltage then subsequently switches off the relay 92. The relay’s contacts 93 and 94 are again opened to release the door chime solenoid holding current. Its action rings the second tone, dong. Diode 97 is used to short out any negative pulse at the base of transistor 91 during the capacitor 102 discharge period. Resistor 103 discharges the voltage of capacitor 102.

When the light switch 16 is depressed momentarily, a positive 11.8 volts DC from terminal B of TB1 to terminal K of TB3 is transferred to terminal J by way of diode 87. The zener diode 88 breaks down and induces a positive pulse to the base of transistor 91, but the pulse is grounded by collector to emitter of transistor 98, which is turned on by the base bias that is developed across resistors 99 and 100. This positive De voltage is made possible from TB3 terminal I. The results is no chime operation when the light button switch 16 is pushed.

Diode 87 is used to prevent the circuit of transistor 91 from operating whenever a positive DC voltage appears at terminal J of TB3.

A Light Ringer circuit is generally referred to by the numeral 110 in FIG. 5.

3,886,352 rior photocell on a shaded area to avoid direct sun and rain. The interior photocell is mounted within a garage at the same level as headlights, or 20 % inches from the ground to detect headlights of cars for triggering sys5 tern when a car is parked in garage. In a two-car garage, the interior photocell may be centrally mounted between the two cars to detect either or both car headlights.

In some cases, such as in drive through carports, no II) wall is available for mounting of an interior photocell, a pneumatic switch may be substituted for the interior photocell. A closed air hose supplies a pulse of air to switch on the system as an automobile crosses the hose. A pair of wires connected between the pheumatic 15 switch and TB1 terminals C and D of the main chassis are polarized so the switch won’t operate if wire is hooked up in wrong polarity.

The pneumatic switch is also useful for homes with driveways. Place the hose switch on driveway to alert 20 the homeowner of approaching vehicles by means of the door chime and lights.

Manual pushbutton switch for convenience should be installed near the entrance to garage and home. The chime operator box should be mounted next to the 25 main chassis.

The wiring is indicated by the chime operator diagram in FIG. 6 as follows. The push-to-light switch 16, normally connected to TB1 terminals A and B of the main chassis, is connected to K and J terminals of TB3 ³⁰ in the chime operator box. Jumper wires are connected between terminals H, J and K of TB3 to terminals G, A and B of TB1. It is important to check for correct wiring because K-B terminals of both blocks are positive line and H-G terminals are grounded. A pair of ³⁵ wires from terminal M and L is connected in parallel with the door chime button switch to provide chime operation.

The basic garage lights may be wired by licensed electrician to house power lines using existing lamps in ⁴⁰ garage or passageway. This system can be wired into any garage light system without disturbing its normal electrical function. Door lights and interior lights may replace or augment garage lights.

Lights may be wired into the main chassis. An in⁴⁵ staller may mount the main box at a suitable place in the garage, run the 117 volts AC line to the nearest AC outlet, and connect all switch elements as described.