AUTOMATIC HEADLIGHT CONTROL

• US 3,769,519 A
• Filed: 10/12/1972
• Issued: 10/30/1973
• Est. Priority Date: 10/12/1972
• Status: Expired due to Term

• Current Assignee: Michael R. Adamian
• Original Assignee: Michael R. Adamian
• Inventors: Adamian, Michael R.
• Primary Examiner(s): Hohauser, Herman J.
• Application Number:
  US05/296,954
• Time in Patent Office: 383 Days
• Field of Search: 307/1LS,116,117 315/83,82
• US Class Current: 307/10.8
• 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

Abstract

Compact, reliable apparatus operating on electronic principles with no electromechanical parts serves two purposes: one, when the engine is running, to turn on the headlights of a motor vehicle automatically when the ambient level of illumination is such that the headlights should be '"'"''"'"''"'"''"'"'on,'"'"''"'"''"'"''"'"' e.g. at twilight, and, two, to turn the headlights '"'"''"'"''"'"''"'"'off'"'"''"'"''"'"''"'"' automatically in the event the engine stops running. In another aspect, this invention completely eliminates the headlight switch presently used, and performs identical functions through electronic circuitry. It can be modified to operate in conjunction with a headlight switch. In both cases, undesirable battery drain is avoided since it is impossible to stop the vehicle and have the lights accidentally '"'"''"'"''"'"''"'"'on.'"'"''"'"''"'"''"'"' The circuitry is so arranged that the lights remain '"'"''"'"''"'"''"'"'on'"'"''"'"''"'"''"'"' for a predetermined interval following '"'"''"'"''"'"''"'"'switching off'"'"''"'"''"'"''"'"' of the ignition system.

Claims

1. Apparatus for controlling the headlights of a vehicle driven by an internal combustion engine including an electrical ignition system, in accordance with an ambient light condition comprising:

a photoelectric device responsive to said condition, means connected to the ignition system to provide a train of pulses corresponding at least in periodicity to the firing pulses of the ignition system, circuit means responsive to the output of said device and said pulses jointly, a pulse generator to be triggered by said ignition pulses when said device provides an output corresponding to a low level of ambient illumination justifying an '"'"''"'"''"'"''"'"'on'"'"''"'"''"'"''"'"' condition of the headlights and vice versa, the time constant of the pulse generator being so determined as to provide for a length of pulse in excess of the period of the successive ignition pulses and circuit means connected to the output of the pulse generator to control the '"'"''"'"''"'"''"'"'on'"'"''"'"''"'"''"'"' and '"'"''"'"''"'"''"'"'off'"'"''"'"''"'"''"'"' condition of the headlights.

2. Apparatus in accordance with claim 1 in which the means utilizing the detector output information and the ignition pulse information comprises a pair of transistors, one of said pair being individual to the ignition pulse circuit, and having its base connected thereto, and the other thereof being individual to the detector output circuit and having its base connected thereto, the emitter of the said one transistor being connected to the collector of said other transistor, the collector of the said one transistor being connected to the input of the pulse generator to apply a triggering signal thereto and to provide phase reversal of the signal from said one transistor prior to applying the same as a triggering pulse.

3. Apparatus in accordance with claim 1 further characterized in that the headlight filaments are connected with the power source of the vehicle in a series circuit which comprises a unidirectional current flow device having a gate, the output of the pulse generator being connected to the gate to control flow of current to the filaments in accordance with the output of the pulse generator.

4. Apparatus in accordance with claim 1 further characterized by an emergency switch to by-pass the output of the pulse generator in the absence of pulses therefrom and to enable manual operation of the headlights independently of the generator output.

5. The combination in accordance with claim 1 in which the duration of said excess is so regulated by the RC constant of the generator as to allow the headlights to remain '"'"''"'"''"'"''"'"'on'"'"''"'"''"'"''"'"' after the ignition is switched '"'"''"'"''"'"''"'"'off.'"'"''"'"''"'"''"'"'

6. Apparatus in accordance with claim 1 further characterized in that the headlight filaments are connected with the power source of the vehicle in a series circuit with a relay having actuating means, the output of the pulse generator being connected to said means to control flow of current to the filaments in accordance with the output of the generator.

7. Apparatus in accordance with claim 3 in which said device is a silicon controlled rectifier.

8. Apparatus in accordance with claim 1 in which the pulse generator is a monostable multivibrator, the said multivibrator having a pair of input transistors (Q6, Q9) arranged to constitute an '"'"''"'"''"'"''"'"'or'"'"''"'"''"'"''"'"' gate by which either transistor can discharge a capacitor (C2), an RC network (R5C2) which defines the pulse width corresponding to a single input pulse, a diode (CR4) connected in series with the base of a transistor (Q7), which requires a higher voltage at the point A which is one junction drop above the base voltage of transistor (Q7) to turn transistor (Q7) '"'"''"'"''"'"''"'"'on'"'"''"'"''"'"''"'"' which requires higher voltage across capacitor (C2), a feedback network (C3R16), a pair of diodes (CR2, CR3) each connected in series with an individual resistor (R13, R14) to preclude curreNt hugging between the input transistors (Q6, Q9), and a buffer transistor (Q8) connected to the collector of transistor (Q7) through a resistor (R19) connected to the collector of transistor (Q7) to avoid overloading the transistor (Q7) and the feedback network (C3R16).