Motor vehicle headlight control apparatus

• US 3,993,914 A
• Filed: 03/31/1975
• Issued: 11/23/1976
• Est. Priority Date: 03/31/1975
• Status: Expired due to Term

• Current Assignee: Unican Security Systems Ltd (dormakaba Holding AG)
• Original Assignee: Unican Security Systems Ltd (dormakaba Holding AG)
• Inventors: Conrad, John H., Seemann, Joseph P.
• Primary Examiner(s): Miller, J D
• Assistant Examiner(s): Moose, Jr., Harry E.
• Application Number:
  US05/563,349
• Time in Patent Office: 603 Days
• Field of Search: 307/10 BP, 307/10 LS, 307/288, 315/82, 315/83, 315/77, 317/141 S, 317/148.5 R
• US Class Current: 307/10.8
• CPC Class Codes: B60Q 9/001 Alarm devices when the motor is stopped and the lights are on

Abstract

In a vehicle having an ignition switch, headlights and a storage battery, a relay has its winding in series with the battery and the collector-emitter circuit of a transistor and has normally open contacts in a headlight energizing circuit. A resistance-capacitance time delay circuit, connected with the ignition switch, controls bias of the transistor. Hence the transistor conducts whenever the ignition switch is "on" and for a short time after it is turned off; and while it conducts, the relay contacts are closed and the lights are energized.

Claims

1. Apparatus for controlling lights on a vehicle that has an engine, an ignition switch which is in an "on" position when the engine is running and can be moved to an "off" position to stop the engine, and a battery which provides a source of electrical power for the lights, said apparatus being characterized by:

A. a relay having

1. a winding and

2. switching contacts that are normally open but are closed when the winding is energized;

B. means connecting said switching contacts in series with the battery and the lights to provide a light power circuit through which the lights can be energized from the battery when the switching contacts are closed;

C. a current valving device of the type having a control terminal and a pair of other terminals, and which allows current to flow between said other terminals only when current flows between its control terminal and one of said other terminals;

D. means connecting said other terminals of the current valving device in a series circuit that comprises the battery and the winding of the relay, so that the relay winding is energized whenever current flows in a circuit in which the control terminal is connected;

E. time delay circuit means connected with the control terminal and with the battery through the ignition switch, to provide for current flow between the control terminal and said one other terminal at all times that the ignition switch is in its "on" position and for a predetermined time after the ignition switch is moved to its "off" position; and

F. means comprising a diode connected between the ignition switch and the winding of the relay, in bypassing relation to the current valving device and the time delay circuit means, to enable the lights to be energized when the ignition switch is in its "on"l position notwithstanding any failure of said current valving device or said time delay circuit means.

2. Apparatus for controlling lights on a vehicle or the like that has an ignition switch which is in an "on" position when an engine in the vehicle is operating and can be moved to an "off"position to stop the engine, and a battery which provides a source of electrical power for the lights, said apparatus being characterized by:

A. a relay having

1. a winding and

2. a pair of normally open contacts that are closed when the winding is energized;

B. means for connecting said contacts in a series circuit with the battery and the lights to provide for energization of the lights when the contacts are closed;

C. transistor means having a base terminal and having a collector-emitter junction connected in series with said winding and connectable with the battery, for controlling energization of the winding in accordance with bias on said base terminal;

D. means providing a time delay switch and connectable with the ignition switch and comprising a chargeable element that can be charged whenever the ignition switch is in its "on" position and can discharge at a controlled rate when the ignition switch is moved to its "off" position;

E. amplifier means connected with said time delay circuit to be responsive to the state of charge of said chargeable element and connected with the base terminal of the transistor means to control bias on the same; and

F. means for effecting rapid switching on and cutoff of said transistor means, to insure positive opening and closing of the relay contacts, the last-named means comprising means connected with the collector-emitter circuit of the transistor means and in positive feedback relation to said amplifier means.

3. The apparatus of claim 2, further characterized by:

G. a diode connected between the ignition switch and said winding, in bypassing relation to the time delay circuit means, the amplifier means and the transistor means, to provide for energization of the lights whenever the ignition switch is in its "on"position, notwithstanding failure of any of said bypassed means.

4. Apparatus for controlling lights on a vehicle or the like that has an engine, an ignition switch which is in an "on" position when the engine is running and can be moved to an "off" position to stop the engine, and a battery which provides a source of electrical power for the lights, said apparatus being characterized by:

A. a relay having

1. a winding and

2. a pair of normally open contacts that are closed when the winding is energized;

B. means for connecting said contacts in a series circuit with the battery and the lights to provide for energization of the lights when the contacts are closed;

C. transistor means connected in series circuit with said winding and connectable with the battery, said transistor means being responsive to a biasing current to cause current to flow through said winding;

D. biasing circuit means connected with the transistor means and connectable with the ignition switch to provide for flow of biasing current through the transistor means at times when the ignition switch is in its "on"position and for a predetermined time after it has been moved from its "on" to its "off" position, said biasing circuit means comprising

1. a resistance-capacitance time delay circuit in which a capacitor is connected to be charged when the ignition switch is in its "on" position and to be slowly discharged when the ignition switch is moved from its "on"to its "off" position;

2. bias control circuit means comprising amplifier means connected with said transistor means and with the resistance-capacitance time delay circuit; and

3. means providing a positive feedback connection from said series circuit comprising the transistor means to said amplifier means, whereby the amplifier means is caused to have a substantially non-linear response to discharge of the capacitor and thus causes the transistor means to conduct substantially at saturation when the charge on the capacitor is above a predetermined value and to be switched off when said charge reaches said value.