Optics: measuring and testing – Range or remote distance finding – Triangulation ranging to a point with one projected beam
Reexamination Certificate
1999-09-15
2001-05-08
Buczinski, Stephen C. (Department: 3662)
Optics: measuring and testing
Range or remote distance finding
Triangulation ranging to a point with one projected beam
C396S120000, C396S106000
Reexamination Certificate
active
06229596
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rangefinder apparatus for measuring the distance to a range-finding object and, in particular, to an active type rangefinder apparatus used in a camera or the like.
2. Related Background Art
In an active type rangefinder apparatus used in a camera or the like, a luminous flux is projected toward a range-finding object from an infrared light-emitting diode (hereinafter referred to as “IRED”), reflected light of the projected luminous flux is received by a position sensing device (hereinafter referred to as “PSD”), a signal outputted from the PSD is arithmetically processed by a signal processing circuit and an arithmetic circuit so as to be outputted as distance information, and the distance to the range-finding object is detected by a CPU. Also, since errors may occur in the range-finding relied on a single light-projecting operation alone, it is common practice to carry out a plurality of light-projecting operations so as to obtain a plurality of distance information items, which are then integrated by an integrating circuit so as to be averaged.
SUMMARY OF THE INVENTION
In the above-mentioned rangefinder apparatus, however, since a plurality of distance information items are integrated by the integrating circuit so as to be averaged, if the time required for each light-projecting operation is long, then it will take a long time for the range-finding process to complete as the respective times required for the individual light-projecting operations are accumulated.
It is an object of the present invention to provide a rangefinder apparatus whose time parallax is small.
In order to achieve such an object, the rangefinder apparatus in accordance with the present invention comprises light-projecting means for projecting a luminous flux toward a range-finding object; light-receiving means for receiving, at a light-receiving position on a position sensing device corresponding to a distance to the range-finding object, reflected light of the luminous flux projected to the range-finding object and outputting a signal corresponding to the light-receiving position; stationary-light-eliminating means, having a stationary-light-eliminating capacitor, for eliminating a stationary light component from the output signal outputted from the light-receiving means; arithmetic means for carrying out an arithmetic operation according to the output signal from which the stationary light component has been eliminated by the stationary-light-eliminating means and outputting a signal corresponding to the distance to the range-finding object; integrating means, having an integrating capacitor, for discharging or charging the integrating capacitor at a reference voltage, in response to the signal outputted from the arithmetic means, so as to integrate the signal outputted from the arithmetic means and outputting a signal corresponding to a result of the integration; and detecting means for detecting the distance to the range-finding object according to the signal outputted from the integrating means; wherein a light-projecting operation by the light-projecting means is terminated during a period after an end of the integration by the integrating means until the stationary light component outputted from the light-receiving means is started to accumulate in the stationary-light-eliminating capacitor.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not to be considered as limiting the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
REFERENCES:
patent: Re. 35652 (1997-11-01), Nonaka et al.
patent: 5659387 (1997-08-01), Yoshida
patent: 7-181038 (1995-07-01), None
patent: 7-229735 (1995-08-01), None
Buczinski Stephen C.
Fuji Photo Optical Co., Ltd.
Leydig , Voit & Mayer, Ltd.
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