Photography – Having wireless remote control circuit – Camera release
Reexamination Certificate
2000-04-28
2002-01-01
Perkey, W. B. (Department: 2851)
Photography
Having wireless remote control circuit
Camera release
C396S106000, C396S100000, C396S159000
Reexamination Certificate
active
06336004
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a distance measuring equipment for measuring a distance up to a target to be measured in distance using a semiconductor photo detector element such as a silicon photo diode (SPD), and a camera incorporated thereinto such a distance measuring equipment.
2. Description of the Related Art
Hitherto, there is widely spread a camera incorporating thereinto an automatic focusing (AF) device, which is generally referred to as an active type. Such an active type of automatic focusing device adopts a system for measuring a distance up to a camera subject in such a manner that an AF light projection unit and an AF photo detection unit are disposed at intervals of a predetermined base length, light is projected from the AF light projection unit to the camera subject, and light reflected on the camera subject is detected by the AF photo detection unit. As a photo detector element for focusing, for example, a semiconductor element such as an SPD element, which will be described later, is used. In some case, a camera is provided with an automatic flash emission device (an automatic electronic flash device) in which at the time of a photography a flash is projected to a camera subject, a reflected light from the camera subject is detected, and a flash emission is stopped at a timing that the reflected light reaches a predetermined light quantity, and a remote control device for instructing an execution of an operation (for example, a self-timer operation) according to a received light from a remote control equipment (for example, for a self-timer) for controlling the camera in accordance with an emission of light directed to the camera, as well as an automatic focusing device. In such a case, in the camera, the automatic electronic flash device and the remote control device are provided with semiconductor photo detector elements represented by the SPD element, in addition to the semiconductor photo detector element for the automatic focus (AF).
FIG. 9
is a diagram of semiconductor photo detector elements incorporated into the respective devices and their associated circuits, with respect to the conventional camera.
In
FIG. 9
, there are shown an SPD
60
, which is one example of the semiconductor photo detector element for the automatic focus (AF), and an AF-dedicated photo detector circuit
62
, which are provided in an automatic focusing device; and an SPD
63
provided in another device and a dedicated photo detector
64
for the another device. The AF-dedicated photo detector
62
and the dedicated photo detector circuit
64
are connected to an MPU (Micro Processor Unit)
65
serving as a control unit. Here, there will be explained a case where the camera is provided with an automatic electronic flash device as the “another device”.
The SPD
60
shown in
FIG. 9
has a detection surface
61
which is divided into two detection areas. The SPD
60
generates a photo-current in such a manner that light for focusing is projected from an AF light projection unit (not illustrated) to a camera subject and the light for focusing reflected on the camera subject is detected on the two detection areas of the detection surface
61
. The photo-current thus generated is separated into photo-currents I
1
and I
2
in accordance with light quantities irradiated onto the two detection areas of the detection surface
61
, respectively, and the photo-currents I
1
and I
2
are fed to the AF-dedicated photo detector circuit
62
. The AF-dedicated photo detector circuit
62
determines a distance up to the camera subject in accordance with both the photo-currents I
1
and I
2
. The MPU
65
controls a lens driving for focusing in accordance with the distance thus determined.
On the other hand, the SPD
63
detects the reflected light from the camera subject through the flash projected to the camera subject from an automatic electronic flash device at the time of photography. A photo-current I
3
generated through the detection by the SPD
63
conducts via the dedicated photo detector circuit
64
. The dedicated photo detector circuit
64
integrates the photo-current I
3
and outputs a signal to stop the flashing operation of the automatic electronic flash device in the timing that the integrated photo-current I
3
reaches a predetermined quantity of reflected light. This signal is transmitted to the MPU
65
as well as a flash emission stop control unit (not illustrated). The MPU
65
performs a control of shutter closing and the like in accordance with this signal.
As mentioned above, in some case, the conventional camera is provided with an automatic electronic flash device and a remote control device as well as an automatic focusing device. In such a camera, although the photo detection wavelengths of those devices are mutually closed, those devices are individually provided with their dedicated photo detector elements. Thus, the conventional camera is associated with a problem that the number of photo detector elements is increased, and as a result a circuit scale is enlarged. Accordingly, there is also raised a problem that the cost is increased.
Further, there is proposed a technology (cf. Japanese Patent Application Laid Open Gazette Hei.7-260475) in which in stead of the AF-dedicated photo detector circuit
62
, the signal of the photo-current is subjected to an A/D conversion and then is operated. However, also in accordance with this technology, the number of photo detector elements is not decreased. This technology is also associated with a problem that the cost is increased.
In order to solve those problems, it is considered that one semiconductor photo detector element is used on a common basis for the automatic focusing device and another device. However, control and processing method for photo detection signals in the automatic focusing device are different from those in another device, for example, an automatic electronic flash device. Therefore, it is difficult for another device to use an AF-dedicated photo detector circuit for processing photo-current from the semiconductor photo detector element as a photo detector circuit as it is.
Further, the camera incorporated therein an automatic focusing device is also associated with an additional problem that as to focusing for distance, an accuracy of focusing is lowered.
SUMMARY OF THE INVENTION
In view of the foregoing, it is an object of the present invention to provide a distance measuring equipment capable of enhancing an accuracy of focusing, and a camera capable of enhancing an accuracy of focusing and/or reducing a cost with a small scale of circuit.
To achieve the above-mentioned object, the present invention provides a distance measuring equipment comprising:
a light projecting unit for projecting light for a distance measurement; and
a photo detector unit, having a light detection window disposed at an interval of a predetermined distance from said light projecting unit in a direction intersecting with a direction of travel of light projected from said light projecting unit, for determining a distance up to a subject in such a manner that light is projected from said light projecting unit, and light reflected on the subject is detected through said light detection window,
wherein said photo detector unit comprises:
a semiconductor photo detector element comprising a detection surface for generating a photo-current upon receipt of irradiation of light, signal electrodes, connected to associated divided areas of said detection surface, respectively, adapted for outputting the photo-current generated by irradiation of light onto said detection surface, and a first switch, disposed at a boundary between divided areas of said detection surface, for selectively offering a first state which permits the photo-current generated on said detection surface to conduct through the associated boundary, and a second state which inhibits the photo-current generated on said detection surface from conducting through the associated boundary, in accordance with a co
Ishii Shuichi
Kotani Takaaki
Ushiro Seimei
Fuji Photo Film Co. , Ltd.
Perkey W. B.
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