Photography – Having variable focal length of camera objective – Having focus operation
Reexamination Certificate
2001-07-03
2003-02-18
Perkey, W. B. (Department: 2851)
Photography
Having variable focal length of camera objective
Having focus operation
C396S092000, C396S121000
Reexamination Certificate
active
06522839
ABSTRACT:
This application claims benefit of Japanese Application No.2000-215106 filed in Japan on Jul. 14, 2000, the contents of which are incorporated by this reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a distance measuring device, an optical sensor, and a camera, such as a film-based camera (silver-halide film camera) or a digital camera, having the distance measuring device.
2. Description of the Related Art
Conventionally, distance measuring devices use a distance measuring sensor provided with a plurality of pairs of line sensors to ensure the measurement of a distance to a subject. For example, one of the distance measuring devices can measure the distance within a wide range by providing distance measuring areas having a plurality of lines. In this distance measuring device, as a larger number of distance measuring areas are arranged corresponding to the line sensors, the subject can be certainly photographed, thereby improving the precision of distance measurement.
In the case of applying the above-mentioned distance measuring device to film-based cameras (silver-halide film cameras) having a zoom lens, there is a problem in that, inconveniently, a space between the distance measuring areas widens relatively to a size of a focal plane and a part of the distance measuring areas is out of the focal plane because even if the distance measuring areas are arranged within a wide range of the focal plane in the case of a low photographing magnification, an angle of view upon photographing is narrow when the a photographing magnification is increased.
Recently, compact size is required for film-based cameras (silver-halide film cameras) and digital cameras and, in association therewith, miniaturization is also required for the distance measuring device. Also, there is a problem in that the space between the distance measuring areas widens by using a distance measuring sensor having the same space between photodetector units even if a focal distance of a distance measuring optical system is reduced so as to miniaturize it.
Then, in order to solve the inconvenience of the above conventional distance measuring device, Japanese Unexamined Patent Application Publication No. 11-153751 proposes a distance measuring device in which a photodetector unit and a processing unit form an L-shaped pattern every pixel of a line sensor and a distance measuring sensor is composed of a train of the photodetector units and a train of the processing units to join the patterns of adjacent pixels to each other. In the case of a distance measuring area which is symmetrical in the vertical direction, the photodetector unit of the line sensor having the pattern is arranged to a symmetric axis of the distance measuring area.
However, even if applying the line sensor of the distance measuring device in the Japanese Unexamined Patent Application Publication No. 11-153751, inconveniently, the space between the distance measuring areas is much wider because the processing unit exists between the photodetector units.
FIG. 15A
is a diagram showing the arrangement of the line sensor of the above distance measuring device. Referring to
FIG. 15A
, in the distance measuring device, a distance measuring sensor
201
comprises: a center line-sensor
211
; an upper line-sensor
212
; and a lower line-sensor
213
. The center line sensor
211
comprises a train of photodetector units
211
a
and trains of processing units
211
b
1
and
211
b
2
which are arranged on upper and lower sides of the train of photodetector units
211
a,
respectively. The upper line-sensor
212
comprises a train of photodetector units
212
a
and a train of processing units
212
b
which is arranged on the upper side of the train of photodetector units
212
a.
The lower line-sensor
213
comprises a train of photodetector units
213
a
and a train of processing units
213
b
which is arranged on the lower side of the train of photodetector units
213
a.
As described above, the trains of processing units are provided between the trains of photodetector units, thus widening inter-trains of photodetector units.
It is considered that an IC process for manufacturing the distance measuring sensor is made fine to reduce the size of a processing circuit unit, thereby further reducing a space between the photodetector units. However, this method has a problem in that costs are increased and it is not appreciable to the cameras.
In a distance measuring device disclosed in Japanese Unexamined Patent Application Publication No. 11-153749, line sensors are arranged linear-symmetrically to an imaginary line, and trains of photodetector units are closer to the imaginary line, rather than trains of processing units. This arrangement causes a space between photodetector units to be narrow.
However, in the line sensors of the distance measuring device disclosed in the Japanese Unexamined Patent Application Publication No. 11-153749, inconveniently, a space of one part of photodetector units is much close thereto, a space of the other part is much wide, and the arrangement of the distance measuring areas becomes unbalanced.
FIG. 15B
is a diagram showing the arrangement of the line sensors in the above distance measuring device. Referring to
FIG. 15B
, in the distance measuring device, a distance measuring sensor
202
comprises: a center line-sensor
221
; a lower line-sensor
222
; and an upper line-sensor
223
. The center line-sensor
221
comprises a train of photodetector units
221
a
and a train of processing units
221
b
which is arranged on the upper side of the train of photodetector units
221
a.
The lower line-sensor
222
comprises a train of photodetector units
222
a
and a train of processing units
222
b
which is arranged on the lower side of the train of photodetector units
222
a.
The upper line-sensor
223
comprises a train of photodetector units
223
a
and a train of processing units
223
b
which is arranged on the upper side of the train of photodetector units
223
a
. As shown in
FIG. 15B
, the trains of photodetector units
221
a
and
222
a
are exceedingly close to each other, and the trains of photodetector units
221
a
and
223
a
are exceedingly far from each other., thus exhibiting the asymetry of the arrangement.
SUMMARY OF THE INVENTION
To solve the above-mentioned inconveniences, according to the present invention, it is one object of the present invention to provide a distance measuring device having a plurality of pairs of line sensors with low costs whereby the density of distance measuring areas can be sufficiently maintained if a photographing magnification is increased and if a distance measuring optical system is reduced in size, and a distance to a subject can be measured without fail by the proper arrangement of line sensors. Also, it is another object of the present invention to provide a camera incorporating the above-mentioned distance measuring device. Further, it is another object of the present invention to provide an optical sensor having a plurality of pairs of line sensors whereby the density of a detecting area can be sufficiently maintained if a detecting magnification is increased and if the size is miniaturized, and accurate detection becomes possible by the proper arrangement of line sensors.
According to the present invention, there is provided a distance measuring device comprising: an optical system for dividing an image of a subject and forming the image; and a plurality of line sensors arranged substantially onto an image-forming plane of the optical system, each of which has a train of photodetector units composed of a plurality of pixels for receiving light of the subject image which passes through the optical system and a train of processing units for processing and outputting a charge generated in the train of photodetector units, wherein at least one of the plurality of line sensors divides the train of photodetector units into a plurality of blocks, of the train of processing units corresponding to each block, one part of train of
Perkey W. B.
Pokotylo John C.
Straub & Polotylo
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