Optics: measuring and testing – Position or displacement
Reexamination Certificate
2000-03-01
2001-10-16
Pham, Hoa Q. (Department: 2877)
Optics: measuring and testing
Position or displacement
C396S061000
Reexamination Certificate
active
06304331
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an exposure control device and a distance measuring device.
Conventionally, exposure control devices are provided with a stroboscope or the like, for use in cameras or the like include one, in which a stroboscope is made constant in amount of luminescence, for example, at a time to change a diaphragm at the time of stroboscope radiation, depending upon a distance up to an object. Concretely, a diaphragm F serving as a standard at the time of stroboscope radiation is found from the following formula (1) on the basis of a distance L up to an object and a guide number GNo of a stroboscope, and the diaphragm F thus found is corrected on the basis of film sensitivity to provide a diaphragm F′ at the time of stroboscope radiation, so-called, there is FM operation to provide a diaphragm F′ at the time of stroboscope radiation.
F=GNo/L
(1)
Also, some exposure control devices change an amount of luminescence of a stroboscope on the basis of a distance to the object to be photographed, and some ones automatically detect a distance up to an object.
With the above described exposure control devices, however, a reflection coefficient of an object is not taken account of, that is, it is assumed that a reflection coefficient of an object to be photographed is constant. Accordingly, in the case where a reflection coefficient of an object is high even when a distance up to an object is the same, an amount of luminescence passing through a shutter aperture increases in amount, and in the case where a reflection coefficient of an object is low, an amount of luminescence passing through a shutter aperture decreases in amount. That is, there has been a problem that an amount of luminescence passing through a shutter aperture varies due to a difference in reflection coefficients of objects to be photographed.
Also, the above described problem gives rise to a problem that, in the case where light passing through a shutter aperture subjects a sensitive member to exposure, a degree of exposure varies depending, upon a difference in reflection coefficients of objects to be photographed.
Further, there is a problem that a construction becomes large because of the need of separate constructions for detection of a distance up to an object and for detection of a reflection coefficient of the object when both of the distance and the reflection coefficient are to be detected.
SUMMARY OF THE INVENTION
The invention comprises distance measuring means for detecting a distance up to an object, reflection coefficient detecting means for detecting a reflection coefficient of the object, a flash device for radiating light on the object, and a control circuit for controlling an amount of exposure in use of the flash device in accordance with the distance up to the object and the reflection coefficient of the object, and so can control an amount of exposure in use of the flash device in accordance with the distance up to the object and the reflection coefficient of the object. Accordingly, it is possible to mitigate a problem that an amount of exposure varies depending upon different reflection coefficients of objects, which are disposed at the same distance.
The distance measuring means includes light receiving means adapted to receive light from the object and makes use of an output from the light receiving means to detect the distance up to the object, and the reflection coefficient detecting means detects the reflection coefficient of the object on the basis of an output from the light receiving means, whereby the light receiving means of the distance measuring means can be used to detect the reflection coefficient of the object. Accordingly, it is possible to reduce the number of parts in addition to an effect similar to that described above. In other words, it is possible in an exposure controlling device, which performs measuring a distance to the object, to solve a problem related to an increase in the number of parts, caused by virtue of newly providing a light receiving means for detection of reflection coefficient, which serves to detect a reflection coefficient of an object being detected.
The invention comprises distance measuring means having light receiving means adapted to receive light incident from an object being detected, and making use of an output from the light receiving means to detect a distance up to the object, and reflection coefficient detecting means for detecting a reflection coefficient of the object being detected, on the basis of an output from the light receiving means, and so can detect a reflection coefficient of the object being detected, using the light receiving means for measuring a distance to the object. Accordingly, it is possible to reduce the number of parts. In other words, it is possible to solve a problem related to an increase in the number of parts, caused by virtue of newly providing a light receiving means for detection of reflection coefficient, which serves to detect a reflection coefficient of an object being detected.
REFERENCES:
patent: 4941009 (1990-07-01), Yoshida
patent: 5023647 (1991-06-01), Shiomi et al.
patent: 5687400 (1997-11-01), Ishiguro et al.
patent: 5752063 (1998-05-01), Ishiguro et al.
patent: 5832315 (1998-11-01), Ishiguro
patent: 6029015 (2000-02-01), Ishiguro
patent: 6085040 (2000-07-01), Yasukawa
Jordan and Hamburg LLP
Pham Hoa Q.
Seiko Precision Inc.
LandOfFree
Exposure control device and distance measuring device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Exposure control device and distance measuring device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Exposure control device and distance measuring device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2568112