Contamination sensor for transparent elements having a reflection light barrier and a working voltage controller

• US 5,229,602 A
• Filed: 12/23/1991
• Issued: 07/20/1993
• Est. Priority Date: 07/14/1989
• Status: Expired due to Fees

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Juliger, Peter
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): LE, QUE TAN
• Application Number:
  US07/778,869
• Time in Patent Office: 575 Days
• Field of Search: 250/222.1, 250/222.2, 250/572, 250/573, 250/214 B, 250/214 AL, 356/239, 356/446, 356/445, 356/448, 340/602, 340/458, 340/583
• US Class Current: 250/222.2
• CPC Class Codes: B60Q 1/0023 the element being a sensor, e.g. distance sensor, camera
• CPC Class Codes: B60Q 11/005 for lighting devices, e.g. indicating if lamps are burning or not
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0833 Optical rain sensor
• CPC Class Codes: B60S 1/603 the operation of at least a part of the cleaning means being controlled by electric means

Abstract

A circuit arrangement for detecting foreign bodies on a transparent element, particularly in a motor vehicle, including a dynamically driven reflection light barrier having a light emitting diode, a pulse generator connected electrically to the light emitting diode to produce light pulses and a phototransistor having a collector and an emitter. The phototransistor and the light emitting diode are positioned on the transparent element so the phototransistor receives reflected light produced by the LED. A resistor connects a power supply including a circuit, which can double an operating voltage in the motor vehicle, to the collector of the phototransistor. To neutralize the effects of stray light, e.g. from headlights of other vehicles, the circuit arrangement is provided with a working point controller connected electrically to the doubler circuit and to the collector of the photoresistor for controlling a voltage difference across the collector and emitter of the photoresistor as a function of an incident extraneous light intensity to compensate for the extraneous light intensity and to obtain an AC output voltage portion from the phototransistor substantially dependent only on the light reflected from the foreign bodies.

Claims

1. A circuit arrangement for an optoelectronic contamination sensor for detecting foreign bodies on a transparent element, said circuit arrangement comprising a dynamically driven reflection light barrier having a receiver structured and positioned to receive light reflected from foreign bodies on a transparent element;

a resistor connected electrically with said receiver;

means for supplying a supply voltage across said receiver and said resistor including a voltage raising circuit for raising an operating voltage to the supply voltage; and

a working point controller means connected electrically to said receiver for controlling a voltage difference across said receiver as a function of an incident extraneous light intensity to compensate for the extraneous light intensity and to obtain an AC output voltage portion from the receiver dependent on the light reflected from the foreign bodies.

2. A circuit arrangement as defined in claim 1, wherein said receiver has a receiver output and a DC voltage portion is produced at the receiver output as well as the AC output voltage portion during operation of the receiver, and further comprising means for averaging the receiver output voltage including the AC portion and the DC portion over time to determine the DC voltage portion when incident extraneous light is present.

3. A circuit arrangement as defined in claim 1, wherein said receiver has a receiver output voltage and further comprising means for raising the output voltage at said receiver when the extraneous light intensity increases.

4. A circuit arrangement as defined in claim 1, wherein said receiver is a photoresistor.

5. A circuit arrangement as defined in claim 1, wherein the voltage raising circuit operative for raising the supply voltage is structured to approximately double the operating voltage.

6. A circuit arrangement as defined in claim 1, wherein the dynamically driven reflection light barrier includes a light emitting diode located adjacent the receiver, said light emitting diode being connected electrically to a pulse generator to generator light pulses for reflection by the foreign bodies and detection by the receiver.

7. A circuit arrangement for an optoelectronic contamination sensor for detecting foreign bodies on a transparent element, said circuit arrangement comprising a dynamically driven reflection light barrier including a receiver for reflected light;

a field-effect transistor connected electrically with said receiver; and

means for supplying a supply voltage across said receiver and said field-effect transistor including a voltage raising circuit operative for raising an operating voltage to the supply voltage; and

a working voltage controller means connected electrically to said receiver and said field-effect transistor for controlling a voltage difference across said receiver as a function of an incident extraneous light intensity on the receiver to compensate for the extraneous light intensity and to isolate an AC output voltage portion of the receiver substantially dependent only on the reflected light.

8. A motor vehicle, comprising a transparent element;

a circuit arrangement for an optoelectronic contamination sensor for detecting foreign bodies on said transparent element, said circuit arrangement having a dynamically driven reflection light barrier having a receiver for reflected light and a resistor connected electrically with said receiver through which a supply voltage is applied to said receiver, a working point controller means for controlling a voltage difference across said receiver as a function of an incident extraneous light intensity on the receiver to compensate for the extraneous light intensity and to isolate a dynamic output voltage portion from the receiver and a voltage raising circuit operative for raising the supply voltage for said receiver; and

an output connected to the receiver and for connection to a cleaning member provided for cleaning said transparent element and controllable by the dynamic output voltage portion of said receiver.

9. A motor vehicle as defined in claim 8, wherein said transparent element is a vehicle window.

10. A motor vehicle as defined in claim 8, wherein said transparent element is a vehicle lens.

11. A motor vehicle as defined in claim 8, wherein said cleaning member is a wiper.

12. A motor vehicle as defined in claim 8, wherein said cleaning member is a washing device.

13. A motor vehicle as defined in claim 8, wherein said transparent element is a lens of a motor vehicle headlamp, said reflection light barrier being arranged in the region of said lens of said motor vehicle headlamp.

14. A circuit arrangement for an optoelectronic contamination sensor for detecting foreign bodies on a transparent element, said circuit arrangement comprising a dynamically driven reflection light barrier including a light emitting diode, a pulse generator connected electrically to the light emitting diode to produce light pulses and a phototransistor having a collector and an emitter, said phototransistor and said light emitting diode being positioned on a transparent element so said phototransistor receives light reflected from foreign bodies on the transparent element as well as incident extraneous light;

a resistor connected electrically with the collector of said phototransistor;

means for applying a supply voltage across the resistor and the phototransistor; and

a working point controller means connected electrically to the collector of said photoresistor for controlling a voltage difference across the collector and emitter of the photoresistor as a function of the incident extraneous light intensity to compensate for the incident extraneous light intensity and to obtain an AC output voltage portion from the phototransistor determined by the light reflected from the foreign bodies.

15. A circuit arrangement as defined in claim 14, wherein the transparent element is located in a motor vehicle having means for providing an operating voltage and further comprising a voltage raising circuit operative for increasing the operating voltage to provide the supply voltage for the photoresistor.

16. A circuit arrangement as defined in claim 15, wherein the transparent element is a lens of a motor vehicle head lamp of the motor vehicle.