VEHICLE EXTERIOR LIGHTING SYSTEM CONTROL CIRCUIT

• US 3,840,777 A
• Filed: 06/11/1973
• Issued: 10/08/1974
• Est. Priority Date: 06/11/1973
• Status: Expired due to Term

• Current Assignee: Dale E. Schelling, Eugene W. Brock
• Original Assignee: Dale E. Schelling, Eugene W. Brock
• Inventors: Brock, Eugene W., Schelling, Dale E.
• Primary Examiner(s): Kominski, John
• Assistant Examiner(s): Mullins, James B.
• Application Number:
  US05/368,634
• Time in Patent Office: 484 Days
• Field of Search: 315/82,83,149,156,157,159
• US Class Current: 315/82
• CPC Class Codes: B60Q 1/1423 Automatic dimming circuits, i.e. switching between high beam and low beam due to change of ambient light or light level in road traffic
• CPC Class Codes: B60Q 2300/052 Switching delay, i.e. the beam is not switched or changed instantaneously upon occurrence of a condition change
• CPC Class Codes: B60Q 2300/314 Ambient light
• CPC Class Codes: B60Q 2300/3321 Detection of streetlights
• CPC Class Codes: B60Q 2300/337 Tunnels or bridges
• CPC Class Codes: B60Q 2300/42 oncoming vehicle

Abstract

A vehicle exterior lighting system control circuit wherein the collector-emitter electrodes of the output transistor of a Schmitt trigger circuit are connected in series with the operating coil of a normally open double pole-single throw relay across the vehicle battery. A light sensitive control element is responsive to conditions of ambient light less than a predetermined level to operate the trigger circuit to the operating state in which the output transistor is conductive, thereby energizing the operating coil of the relay which energizes the vehicle exterior lighting system circuit, and to conditions of ambient light greater than the predetermined level to operate the trigger circuit to the other operating state in which the output transistor is not conductive. A time delay circuit is disposed between the trigger circuit and the light sensitive control element for introducing a delay in the operation of the trigger circuit from either operating state to the other and another time delay circuit is in operative relationship with the base electrode of the trigger circuit output transistor for maintaining the output transistor conductive for a predetermined period of time after the ignition switch has been operated to the open condition.

Claims

1. A vehicle exterior lighting system control circuiT comprising in combination with the vehicle head lamps and tail lamps, a source of electrical power and an ignition switch operable to electrical circuit open and close conditions:

an electrical switching device of the type operable to the electrical circuit closed condition in response to an electrical current for establishing energizing circuits for said vehicle headlamps and tail lamps across said source of electrical power, a trigger circuit having input and output transistors and two operating states, one for establishing and the other for interrupting a circuit for the flow of said electrical current for said electrical switching device while said ignition switch is operated to the electrical circuit closed condition, a light sensitive control element responsive to conditions of ambient light for operating said trigger circuit to said one operating state with conditions of ambient light less than a predetermined level and to said other operating state with conditions of ambient light greater than said predetermined level, and a time delay circuit disposed between said input transistor of said trigger circuit and said light sensitive control element for introducing a delay in the operation of said trigger circuit from either said operating state to the other.

2. A vehicle exterior lighting system control circuit comprising in combination with the vehicle headlamps and tail lamps, a source of electrical power and an ignition switch operable to electrical circuit open and closed conditions:

an electrical switching device of the type operable to the electrical circuit closed condition in response to an electrical current for establishing energizing circuits for said vehicle headlamps and tail lamps across said source of electrical power, a trigger circuit having input and output transistors and two operating states, one for establishing and the other for interrupting a circuit for the flow of said electrical current for said electrical switching device while said ignition switch is operated to the electrical circuit closed condition, a light sensitive control element responsive to conditions of ambient light for operating said trigger circuit to said one operating state with conditions of ambient light less than a predetermined level and to said other operating state with conditions of ambient light greater than said predetermined level, a first time delay circuit disposed between said input transistor of said trigger circuit and said light sensitive control element for introducing a delay in the operation of said trigger circuit from either said operating state to the other, and a second time delay circuit for maintaining said trigger circuit in said one operating state for a predetermined period of time after said ignition switch has been operated to the electrical circuit open condition.

3. A vehicle exterior lighting system control circuit comprising in combination with the vehicle headlamps and tail lamps, a source of electrical power and an ignition switch operable to electrical circuit open and closed conditions:

an electrical relay having an operating coil and two normally open contacts operable to the electrical circuit closed condition in response to the energization of said operating coil for establishing respective energizing circuits for said vehicle headlamps and tail lamps across said source of electrical power, a trigger circuit having input and output transistors and two operating states, one for establishing and the other for interrupting the energizing circuit of said operating coil of said electrical relay while said ignition switch is operated to the electrical circuit closed condition, a light sensitive control element responsive to conditions of ambient light for operating said trigger circuit to said one operating state with conditions of ambient light less than a predetermined level and to said other operating state with conditions of ambient light greater than said predetermined level, a first time delay circuit disposed between said input transisTor of said trigger circuit and said light sensitive control element for introducing a delay in the operation of said trigger circuit from either said operating state to the other, and a second time delay circuit for maintaining said trigger circuit in said one operating state for a predetermined period of time after said ignition switch has been operated to the electrical circuit open condition.