Apparatus for controlling a windscreen wiping system

• US 5,237,249 A
• Filed: 06/23/1992
• Issued: 08/17/1993
• Est. Priority Date: 05/26/1992
• Status: Expired due to Term

• Current Assignee: Leopold Kostal GmbH & Company KG
• Original Assignee: Leopold Kostal GmbH & Company KG
• Inventors: Levers, Juergen
• Primary Examiner(s): Ro, Bentsu
• Application Number:
  US07/902,384
• Time in Patent Office: 420 Days
• Field of Search: 318/480, 318/483, 318/443, 318/444, 318/DIG. 2, 15/250.12, 15/250.17, 307/9.1, 307/10.1
• US Class Current: 318/443
• CPC Class Codes: B60S 1/0818 including control systems responsive to external conditions, e.g. by detection of moisture, dirt or the like
• CPC Class Codes: B60S 1/0833 Optical rain sensor
• CPC Class Codes: Y10S 318/02 Windshield wiper controls

Abstract

Apparatus is provided for controlling a windscreen wiping system. The apparatus includes a circuit arrangement which includes a microcontroller, a clock generator unit comprising a switch and a clock-pulse generator, an I/V converter, a phase-selective rectifier and an amplifier with a low-pass characteristic. The apparatus also includes an optoelectronic apparatus having IR beam transmitters for transmitting useful signals in clocked form and IR beam receivers for receiving the transmitted useful signals. The IR beams which are transmitted are influenced between the IR beam transmitters and the IR beam receivers by a liquid or solid coating on the screen, such that the signals received by IR beam receivers are varied in dependence upon the coating present on the screen. The amplifier filters out the interference quantities of the ambient light to obtain a processed useful signal. The signal received by the IR beam receivers are converted by the circuit arrangement into control signals by means of which operation of the drive motor is controlled. The IR beam receivers are provided with at least one load resistor, and the voltage drop at the at least one load resistor caused by rapid changes in the ambient light received by the IR beam receivers is used as a correcting quantity for the useful signal to eliminate influences of ambient light, thereby preventing unwanted triggering of the windscreen wiping system.

Claims

1. Apparatus for controlling a windscreen wiping system having a drive motor for driving at least one windscreen wiper arm for cleaning the outer surface of a screen, the apparatus having an optoelectronic device disposed in the wiped area on the inner surface of the screen, the apparatus comprising:

the optoelectronic device including at least one IR beam transmitter for transmitting useful signals in clocked form and at least one IR beam receiver for receiving the transmitted useful signals, the IR beams which are transmitted being influenced between the at least one IR beam transmitter and the at least one IR beam receiver by a liquid or solid coating on the screen, such that the signals received by the at least one IR beam receiver are varied in dependence upon the coating present on the screen; and

a circuit arrangement, connected to the optoelectronic device and the drive motor, including at least one I/V converter for amplifying an alternating component of the received signals and generating an output signal, a phase-selective rectifier for narrow-band filtering and rectifying a clocked component of the output signal of the I/V converter, and an amplifier having a low-pass characteristic for filtering out the interference quantities of the ambient light to obtain a processed useful signal, the circuit arrangement of the windscreen wiping system also including a microcontroller having a basic setting value which is determined by the optoelectronic device when the screen is optimally clean, the basic setting value representing the quasi-static conditions of the components provided for detecting the coating present on the screen and being stored in a non-volatile memory, the basic setting value big used as a starting value for all subsequent startups of the windscreen wiping system,

said received signals being converted by the circuit arrangement into control signals by means of which operation of the drive motor is controlled, wherein the at least one IR beam receiver is provided with at least one load resistor, and the voltage drop at the at least one load resistor caused by rapid changes in the ambient light received by the at least one beam receiver is used as a correcting quantity for the useful signal to eliminate influences of ambient light, thereby preventing unwanted triggering of the windscreen wiping system.

2. The apparatus of claim 1, wherein the correcting quantity and the processed useful signal are supplied to the microcontroller, the microcontroller generating the control signals based on the correcting quantity and the processed useful signal.

3. The apparatus of claim wherein the circuit arrangement includes a first operational amplifier associated with the IR beam receiver for processing the voltage drop at the at least one load resistor into the correcting quantity, and a second operational amplifier in electrical communication with the amplifier having a low-pass characteristic and the first operational amplifier, the processed useful signal and the correcting quantity being supplied to the second operational amplifier, the second operational amplifier by means of the correcting quantity eliminating the variations in the processed useful signal caused by the ambient light and providing a control signal to the microcontroller.