Data processing: measuring – calibrating – or testing – Measurement system – Orientation or position
Reexamination Certificate
1999-09-16
2001-12-11
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Orientation or position
C701S041000, C250S231160, C180S400000, C341S003000
Reexamination Certificate
active
06330522
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a detector and a method for detecting the rotational speed of a rotative member. More particularly, the present invention pertains to a detector and method for detecting a rotational angle of a vehicle steering shaft.
A typical rotational angle detector includes a rotor attached to a steering shaft. Slits are formed along a single circumference on the rotor. Luminous elements are arranged at one side of the rotor. Photodetectors, each of which corresponds to one of the luminous elements, are arranged at the opposite side of the rotor. When receiving light from the corresponding luminous element, each photodetector outputs a signal of H level. When light from the luminous element does not reach the photodetector, the photodetector outputs a signal of L level. A combination of signals of H level and signals of L level from the photodetectors represents a single reflective code.
The rotational angle detector has a memory. The memory previously stores data representing the relationship between reflective codes and rotational angles of the rotor. When a reflective code is generated based on signals from the luminous elements and the photodetectors, a pattern of reflective code that corresponds to the generated reflective code is retrieved from the memory. The rotational angle of the steering wheel is obtained based on the retrieved pattern data, which corresponds to the generated reflective code.
However, the above described rotational angle detector stores pattern data that correspond to all the reflective codes, which requires an increased memory capacity. Therefore, the manufacturing of the detector is costly.
SUMMARY OF THE INVENTION
Accordingly, it is an objective of the present invention to provide a rotational angle detector that reduces required memory capacity.
Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompany drawing, illustrating by way of example the principles of the invention.
REFERENCES:
patent: 4996657 (1991-02-01), Shiraishi et al.
patent: 5065324 (1991-11-01), Oshita et al.
patent: 5073710 (1991-12-01), Takagi et al.
patent: 5243188 (1993-09-01), Hattori et al.
patent: 5283740 (1994-02-01), Sato et al.
patent: 5787375 (1998-07-01), Madau et al.
Akerman & Senterfitt
Hoff Marc S.
Kabushiki Kaisha Tokai Rika Denki Seisakusho
Vo Hien
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