Outside rear view mirror with position sensor

Details Outside rear view mirror with position sensor Outside rear view mirror with position sensor

2000-10-27

2002-05-07

Sikder, Mohammad (Department: 2872)

Optical: systems and elements

Mirror

With support

C358S461000, C358S461000, C358S296000

Reexamination Certificate

active

06382806

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to an outside rear view mirror for motor vehicles having an adjustably supported glass subassembly and an electric adjusting mechanism for remote-controlled adjustment of the glass subassembly, wherein the position of the glass subassembly, in particular the angular position, is determinable by means of at least one sensor.
BACKGROUND OF THE INVENTION
Outside rear view mirrors of the type described above are known from prior art. Such outside rear view mirrors comprise an adjusting mechanism for adjusting the mirror glass, which is provided on the glass subassembly. The driver is therefore able by remote control to adapt the glass subassembly of the outside rear view mirror to his individual requirements. More prestigious vehicles have a so-called memory function. For such memory function specific settings, e.g. of the driver's seat and in particular also of the outside rear view mirrors, are stored so that, after a change of driver, the memory function merely has to be tripped for the seat and/or the outside rear view mirrors to be brought into the correct setting for the driver. For such functions, the position of the glass subassembly has to be detectable by means of a sensor in order to store the various setting values for the various drivers after the initial start-up and enable start-up upon subsequent tripping of the memory function.
From prior art so-called memory potentiometers are known, which are fitted in outside rear view mirrors as sensors for determining the position of the glass subassembly. Depending on the position of the glass subassembly, corresponding voltage output values associated with an angular position arise at the memory potentiometer. For this purpose, the potentiometers fitted e.g. in the glass adjusting mechanisms are supplied with an input voltage of e.g. 5 V DC. Depending on the position of the glass subassembly, an output voltage of between 5% and 95% of the applied input voltage may then be tapped at the memory potentiometers. From the voltage drop between input voltage and output voltage it is to therefore possible to derive the position of the glass subassembly.
The drawback of the known sensors for determining the position of the glass subassembly in an outside rear view mirror is that their functioning may be impaired by corrosion. As soon as water, especially combined with salt, penetrates the outside mirror, the sensitive resistive lines or sliders of the memory potentiometers may become damaged and therefore cause failures of the memory function.
SUMMARY AND OBJECTS OF THE INVENTION
The object of the present invention is to provide an outside rear view mirror, in which the position of the glass subassembly is determinable by means of a sensor which is insensitive to corrosion.
This object is achieved by an outside rear view mirror having an adjustably supported glass subassembly and an electric adjusting mechanism for remote-controlled adjustment of the glass subassembly, wherein the position of the glass subassembly, in particular the angular position, is determinable by means of at least one sensor. The sensor is designed in the manner of a magnetic sensor, which cooperates in such a way with a magnetic element provided in the outside rear view mirror that the magnetic sensor or the magnetic element participates in the adjusting motion of the glass subassembly and the magnetic sensor in dependence upon the position of the magnetic element supplies a variable output signal, from which in an evaluation unit the position of the glass subassembly is derivable.
The invention is based on the fundamental idea of using a sensor which operates without contact to determine the position of the glass subassembly. It has in such case proved a particularly suitable operating principle to use the variation of the magnetic field strength as a function of the arrangement of a measuring point in a magnetic field to measure the position of the glass subassembly in the agreed manner.
According to the invention it is therefore proposed to design the sensor in the manner of a magnetic sensor, which in the outside rear view mirror cooperates with a magnetic element, i.e. a component surrounded by a magnetic field, e.g. a permanent magnet, in such a way that the magnetic sensor or the magnetic element participates in the adjusting motion of the glass subassembly, with the result that the adjustment of the glass subassembly gives rise to a relative movement between magnetic sensor and magnetic element. The magnetic sensor is consequently moved in the magnetic field of the magnetic element and is therefore exposed, depending on the position of the glass subassembly, to different field intensities in the magnetic field of the magnetic element. Depending on the respective field intensity the magnetic sensor supplies a variable output signal, wherein a specific position of the glass subassembly is associated with the output signal so that by evaluation of the output signal in an evaluation unit the position of the glass subassembly is derivable. Thus, a reliable sensor is available for non-contact measurement of the position of the glass subassembly. In principle, it is of no importance to the function of the invention whether the magnetic sensor or the magnetic element participates in the adjusting motion of the glass subassembly. As in many cases it will admittedly be easier to arrange the magnetic sensor in a fixed manner and the magnetic element in a movable manner, the following description is based on this type of arrangement. The reverse arrangement is however likewise realizable without difficulty.
The magnetic sensor may, in principle, be of any desired design so long as it generates an output signal which varies with the change of position of the magnetic element in the magnetic field. For example, the use of GMR sensors, magnetoresistors or magnetoresistive sensors is conceivable. Particularly suitable are so-called Hall-effect sensors because said type of sensor is already commercially available at low cost together with correspondingly suitable magnetic elements, e.g. permanent magnets obtained by vacuum melting. Hall-effect sensors present good spatial resolution even with low positioning motion amplitudes.
In order to evaluate the output signal of the magnetic sensor, the output signal has to be relayed to an evaluation unit, e.g. the central processing unit in a motor vehicle. In order to guarantee reliable signal transfer even in the event of extended conductor paths, it is advantageous for the output signal to have a relatively high voltage level. It is therefore to advantageous to integrate a signal amplifying circuit in the magnetic sensor so that the output signals may be proportionally boosted. It is further advantageous for the magnetic sensor to comprise a temperature compensating circuit so that the measurement result is not corrupted by temperature influences.
It is particularly advantageous when the magnetic sensor may be supplied with a supply voltage of around 5 V DC as said supply voltage has also already been used previously for supplying the known sensors, so that there is no need to adapt the supply voltage to the new magnetic sensors. However, in principle any other supply voltage is also conceivable so long as it may be made available in the vehicle.
It is furthermore advantageous when the magnetic sensor in dependence upon the position of the magnetic element produces an output voltage in the voltage range of 5% to 95% of the supply voltage because said voltage range likewise corresponds to the previously used voltage range, with the result that the previously used evaluation units may continue to be used substantially without modification. However, in principle any other voltage range is also conceivable so long as it enables an adequate accuracy of the measuring signals over the positioning range.
In principle, the use of any magnetic element which builds up a magnetic field is conceivable in the outside rear view mirror according to the invention. For example, it is also po

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