Optics: measuring and testing – Range or remote distance finding – With photodetection
Reexamination Certificate
2002-03-28
2004-04-06
Buczinski, Stephen C. (Department: 3662)
Optics: measuring and testing
Range or remote distance finding
With photodetection
C356S005080
Reexamination Certificate
active
06717656
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laser range detector and more particularly pertains to a method and apparatus for a laser range detector to detect a distance precisely.
2. Description of the Related Art
It is convenient to use a laser beam to detect the distance from a laser range detector to a target point.
FIG. 1
of the drawings illustrates a structure of a laser range detector in the prior art. A MPU
130
outputs a trigger signal to a clock unit
120
, the clock unit
120
receives the trigger signal and outputs an emitting signal to an emitter
110
and outputs a clock signal to a sampler
160
. The emitter
110
receives the emitting signal and outputs a pulse S
0
to a target point and a receiver
150
receives a pulse S
1
reflected from the target point, the features of the pulse S
1
, for example, the waveform or the period are similar to the pulse S
0
. The receiver
150
outputs the pulse S
1
to the sampler
160
. The sampler
160
samples the pulse S
1
according to the clock signal and outputs pulse clock data corresponding to the pulse S
1
to a register
170
. The register
170
stores the pulse clock data. The MPU
130
receives the pulse clock data from the register
170
and calculates the time between the pulse S
0
and S
1
, then calculates the distance to a target point.
A problem with the laser range detector is the precision of the detection. As illustrated in
FIG. 2
, a pulse S
0
is output by a laser range detector, a pulse S
1
and a pulse S
2
are reflected by the target and are received by a laser range detector, wherein the pulse S
1
and S
2
are sampled at the same clock so the distances calculated are the same (both at 122
th
clock). In fact, the distances are different because the pulse S
11
and S
21
are not the same. A faster clock generator can improve the precision of the detection because a pulse can be sampled more times. But a faster clock generator is expensive and a circuit working at a faster clock is complicated.
SUMMARY OF THE INVENTION
In view of the foregoing disadvantage inherent in the laser range detector in the prior art, it is one object of the present invention to provide a method and an apparatus to detect a distance precisely for a laser range detector.
To attain the object, the present invention provides a method for a laser range detector to detect a distance precisely. The method including the following steps: first, emitting a first signal to a target; second, receiving a second signal which is the first signal reflected by the target; then generating one or more delay signals; then generating a plurality of pulse clock data from sampling the second signal or the delay signals; then calculating a precise time according to the pulse clock data; and calculating a precise distance according to the precise time, wherein each delay signal is delayed for a multiple default time from the second signal and the period of the second signal is smaller than the default time.
To attain the object,.the present invention provides an apparatus for a laser range detector to generate a plurality of delay signals, the apparatus including: an input terminal for inputting a second signal; and one or more delay units for generating one or more delay signals; and a switching circuit for selectively outputting one of the second signals or the delay signals; wherein the feature of the delay signal is similar to the second signal.
To attain the object, the present invention provides an apparatus for a laser range detector to detect a distance precisely, the apparatus including: a processor for calculating a precise time and a precise distance; and a clock generator for outputting clock signals; and an emitter for emitting a first signal to a target; and a receiver for receiving a second signal collided from a target; and a delay circuit for passing the second signal and outputting one or more delay signals; and a sampler for sampling the second signal or the delay signals; and-a register for storing a plurality of pulse clock data corresponding to the second signal or the delay signals; wherein the feature of the second signal and the delay signals are similar to the first signal.
REFERENCES:
patent: 3853402 (1974-12-01), Nichols
patent: 3900261 (1975-08-01), Wingate
patent: 4569599 (1986-02-01), Bolkow et al.
patent: 5054911 (1991-10-01), Ohishi et al.
patent: 5262837 (1993-11-01), Shyy
patent: 5852491 (1998-12-01), Kato
patent: 6133992 (2000-10-01), Tanaka et al.
patent: 6229598 (2001-05-01), Yoshida
Chien Pie-Yau
Wu Chia-Jung
Asian Optical Co. Ltd.
Buczinski Stephen C.
Thomas Kayden Horstemeyer & Risley
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