Apparatus for measuring the speed of an object with circuit for converting analog signals into logic signals and circuit for varying sensitivity
AssigneeBendix Electronics S.A.
InventorMichel Suquet
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Abstract
The circuit comprises a comparator 1 fed by a quasi-sinusoidal signal delivered by a source 2 for converting the positive alternations of the signal into pulses acceptable by digital computing means. According to the invention, the circuit comprises a current source 7 selectively connectible to the circuit in order to vary its sensitivity and to thus enable an evaluation of the amplitude of the signal delivered by the source 2. Application to the diagnosis of the operating state of a variable reluctance sensor delivering a quasi-sinusoidal signal representing the speed of rotation of a shaft fitted in a motor vehicle.
Claims12
A circuit for converting an analog electrical signal into a pulsed logic signal, comprising:
- a source for generating the analog signal,
- a comparator having first and second inputs between which the analog signal is applied,
- a DC bias voltage source connected by one terminal to said first and second inputs through first and second resistors respectively and
- means for selectively varying the input voltage sensitivity of the circuit,
- said means comprising:
- a current source (7),
- a switching device (8) for selectively connecting said current source between said first input of said comparator and the other terminal of said voltage source,
- said current source providing a predetermined offset voltage at the terminals of said first resistor (R.sub.4), for selecting the voltage amplitude of the analog signal for generating pulsed logic signals at the output of said comparator.
Dependencies are inferred from the claim text.