Vehicle headlamp system with series high beam daylight running lamp operation

• US 4,928,036 A
• Filed: 07/24/1989
• Issued: 05/22/1990
• Est. Priority Date: 11/23/1987
• Status: Expired due to Term

• Current Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Abboud, Pierre Y.
• Primary Examiner(s): Boudreau, Leo H.
• Assistant Examiner(s): Razavi, Michael
• Application Number:
  US07/384,890
• Time in Patent Office: 302 Days
• Field of Search: 315/70, 315/77, 315/76, 315/80, 315/81, 315/82, 315/83, 315/84, 307/10 LS, 307/10 R
• 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 11/00 Arrangement of monitoring devices for devices provided for in groups B60Q1/00 - B60Q9/00
• CPC Class Codes: B60Q 2400/30 Daytime running lights [DRL], e.g. circuits or arrangements therefor

Abstract

A headlamp system provides for the high beam headlamp filaments to be connected in series across the supply voltage for half voltage energization in daytime running lamp operation when the ignition switch is closed, a DRL enabling switch is open and the headlamp switch is not in a headlamp on condition. In normal high beam headlamp operation, the high beam filaments are connected across the supply voltage in parallel for full voltage energization. The DRL enabling switch may be a park brake switch. The headlamp switch may have a fog lamp energizing condition to energize fog lamps; and the system permits such energization when the headlamps are connected in series but not when they are connected in parallel in normal high beam operation. A circuit is provided to sense when one of the high beam filaments is burned out and latch the daytime running light operation off with a signal to the vehicle operator.

Claims

1. A headlamp system for a vehicle with an engine and an ignition switch effective to enable engine operation, the headlamp system comprising, in combination:

a source of electric power at a predetermined supply voltage;

a pair of headlamps on the front of the vehicle, one on each side thereof;

a headlamp switch having closed and open conditions;

a DRL enabling means;

first circuit means connecting one of the headlamps in series with the headlamp switch and electric power source;

a DRL activating switch effective in a first condition to connect the other of the headlamps in parallel with the one of the headlamps and in a second condition to connect the other of the headlamps in series with the one of the headlamps and the electric power source; and

second circuit means responsive to the ignition switch, headlamp switch and DRL enabling means to put the DRL activating switch in its second condition when the ignition switch is activated, the DRL enabling means is enabled and the headlamp switch is in an open condition, whereby the headlamps are both energized at approximately half the predetermined supply voltage for improved visibility of the vehicle to other vehicle operators, and otherwise to put the DRL activating switch in its first condition, whereby the headlamps may both be energized with the full predetermined supply voltage for illumination of the road for vehicle operation with the headlamp switch in its closed condition.

2. The headlamp system of claim 1 wherein the vehicle further comprises brake means for preventing vehicle movement and the DRL enabling means is responsive to the activation of the brake means to be activated only when the brake means is not activated.

3. The headlamp system of claim 1 wherein the headlamps comprise high beam filaments.

4. The headlamp system of claim 2 wherein the headlamps comprise high beam filaments.

5. The headlamp system of claim 1 further comprising third circuit means effective when the DRL activating switch is in its second condition to sense a voltage between the headlamps connected in series and latch the DRL activating switch into its first condition and provide a signal when such voltage indicates a burned out headlamp.

6. The headlamp system of claim 3 further comprising a fog lamp, a fog lamp switch, and third circuit means responsive to the fog lamp switch and the second circuit means to connect the fog lamp in series with the electric power source for energization with closure of the fog lamp switch when the high beam filaments are not connected across the electric power source or are connected in series across the electric power source but prevent such energization when the high beam filaments are connected in parallel across the electric power source.

7. A headlamp system for a vehicle with an engine and an ignition switch effective to enable engine operation, the headlamp system comprising, in combination:

a source of electric power at a predetermined supply voltage;

a pair of headlamps on the front of the vehicle, one on each side thereof, each of the headlamps having a high beam filament;

a headlamp switch having closed and open conditions;

a DRL activating switch comprising a common terminal, a normally open terminal and a normally closed terminal and being connected in series with the headlamps in series and the electric power source through the common and normally open terminals, the DRL activating switch further comprising an activating means effective only when activated to change the connection of the common terminal from the normally closed terminal to the normally open terminal;

a high beam selector switch connected, when in a high beam selected condition, in series with one of the headlamps, the headlamp switch and the electric power source and further in series with the other of the headlamps, the headlamp switch and the electric power source through the common and normally closed terminals of the DRL activating switch;

a DRL enabling means;

third circuit means effective, unless overridden, to connect the activating means of the DRL activating switch in series with the electric power source for activation of the DRL activating switch when the ignition switch is closed;

fourth circuit means responsive to the DRL enabling means to override the third circuit means and prevent activation of the DRL activating switch unless the DRL enabling means is activated; and

fifth circuit means responsive to the headlamp switch to override the third circuit means and prevent activation of the DRL activating switch when the headlamp switch is in its closed condition.

8. The headlamp system of claim 7 wherein the vehicle further comprises brake means for preventing vehicle movement and the DRL enabling means is responsive to the activation of the brake means to be activated only when the brake means is not activated.

9. The headlamp system of claim 7 in which the third circuit means comprises a first transistor switch connected in series with the activating means of the DRL activating switch, the ignition switch and the electric power source and having a control terminal by which it may be activated when the ignition switch is closed or deactivated by the fourth or fifth circuit means, and the fifth circuit means comprises:

a first comparator normally having a first predetermined voltage applied to one input thereof and an output coupled to the control terminal of the first transistor switch;

a resistive network connecting the other input of the first comparator to the electric power source and headlamp switch to generate, when the headlamp switch is in its closed condition and the headlamps are thus connected in parallel across the electric power source, a voltage effective, relative to the first predetermined voltage, to switch the comparator output so as to deactivate the first transistor switch, and otherwise, with neither headlamp burned out, to generate a voltage, relative to the first predetermined voltage, not so effective.

10. The headlamp system of claim 9 further comprising sixth circuit means effective when the DRL activating switch is activated to sense a voltage between the headlamps connected in series and latch the DRL activating switch into its first condition when such voltage, relative to the predetermined supply voltage, indicates a burned out headlamp.

11. A headlamp system for a vehicle with an engine and an ignition switch effective to enable engine operation, the headlamp system comprising, in combination:

a source of electric power at a predetermined supply voltage across first and second power supply terminals;

a headlamp switch;

a high beam select switch;

first and second headlamps on the front of the vehicle, one on each side thereof, the first headlamp having a high beam filament with one end connected through the high beam select and headlamp switches in series to the first power supply terminal and another end connected to the second power supply terminal;

a DRL activating switch comprising a common terminal, a normally open terminal connected to the first power supply terminal and a normally closed terminal connected to the second power supply terminal, the second headlamp having a high beam filament with one end connected to the one end of the high beam filament of the first headlamp to form a junction therebetween and another end connected to the common terminal of the DRL activating switch, the DRL activating switch further comprising an activating means effective only when activated by an electric current therethrough to change the connection of the common terminal from the normally closed terminal to the normally open terminal;

a DRL enabling switch connected in series with the ignition switch with a resistive load therebetween, the ends of the ignition and DRL enabling switches not connected to the resistive load being connected respectively to the first and second power supply terminals;

a transistor switch having a first conducting terminal connected to the second power supply terminal, a second conducting terminal connected through the activating means of the DRL activating switch to the junction of the ignition switch and resistive load, and a control terminal;

first circuit means coupling the electric power source, ignition switch, activating means of the DRL activating switch and transistor switch so as to normally produce conduction of the transistor switch to activate the DRL activating switch when the ignition switch is closed, the first circuit means further coupling the transistor switch to the DRL enabling switch to prevent such conduction of the transistor switch when the DRL enabling switch is closed;

a first comparator having a pair of inputs producing activation or no activation thereof and an output coupled to the transistor switch to prevent conduction thereof when the first comparator is activated;

a first voltage divider connected across the first and second power supply terminals and effective, when not overridden, to apply a first predetermined voltage to one of the inputs of the first comparator;

a second voltage divider connected across the first and second power supply terminals and effective, when not overridden, to apply a second predetermined voltage to the other input of the first comparator effective, relative to the first predetermined voltage, to prevent activation thereof;

second circuit means coupling the junction of the headlamp and high beam select switches to the second voltage divider and effective, when the headlamp switch is closed, to override the second voltage divider and apply a third predetermined voltage to the other input of the first comparator, relative to the first predetermined voltage, to cause activation of the first comparator, the second circuit means being further effective, when the headlamp switch is open and the DRL activating switch is activated, to apply a fourth predetermined voltage, intermediate the first and second predetermined voltages, to the other input of the first comparator relative to the first predetermined voltage, to prevent activation of the first comparator.

12. The headlamp system of claim 11 further comprising:

third circuit means coupling the junction of the headlamps to the second voltage divider, the third circuit means being effective to override the first circuit means when the first or second headlamp burns out and change the voltage at the other input of the first comparator to a voltage essentially the same as that at the second or first power supply terminal, respectively;

a second comparator having one input coupled to the other input of the first comparator to receive essentially the same voltage thereon, an output coupled to the one input of the first comparator to override the first voltage divider and activate the first comparator when activated and further coupled in feedback to the one input thereof to latch the second comparator in an activated state, and another input;

fourth circuit means responsive to the transistor switch to generate and apply to the other input of the second comparator a fifth predetermined voltage when the transistor switch conducts and a sixth predetermined voltage when the transistor switch does not conduct, the fourth circuit means further providing a predetermined time delay in changing from the fifth to the sixth predetermined voltage when the transistor switch changes from conducting to not conducting, the fifth predetermined voltage being effective, relative to the second predetermined voltage, to prevent activation of the second comparator and the sixth predetermined voltage being intermediate the fifth and fourth predetermined voltages and further being effective, relative to the fourth predetermined voltage, to prevent activation of the second comparator, whereby, when the second headlamp high beam filament burns out, the second comparator latches the first comparator to cause deactivation of the DRL activating switch as the voltage at the junction of the high beam filaments crosses the sixth predetermined voltage and, when the first headlamp high beam filament burns out, the second comparator latches the first comparator to cause deactivation of the DRL activating switch after the voltage at the junction of the high beam filaments first changes in one direction to cause deactivation of the DRL activating switch and then immediately changes in the other direction to cross the voltage at the other input of the second comparator before it can complete its delayed change from the sixth to the fifth predetermined voltage.

13. The headlamp system of claim 11 wherein the vehicle further comprises brake means for preventing vehicle movement and the DRL enabling switch is responsive to the activation of the brake means to close only when the brake means is activated and wherein the resistive load is a brake means indicator light with a resistor in parallel therewith to substitute for the brake means indicator light if the latter burns out.