JPH01109329A - Camera - Google Patents

Abstract

PURPOSE:To obtain accurate object luminance information corresponding to the direction of distance measurement by detecting the object luminance with the output of a light measuring photodetector corresponding to the selected direction of distance measurement. CONSTITUTION:When the distance to an object A1 is measured by an LED 4a and an optical element 6a, the object luminance is detected by the output of a light measuring photodetector 7a. When the distance to an object A2 is measured by an LED 4b, the object luminance is detected by a light measuring photodetector 7b; and when the distance to an object A3 is measured by an LED 4c, the object luminance is detected by a light measuring photodetector 7c. Since the direction of light measuring and that of distance measuring coincide with each other, accurate light measuring information is obtained with a low cost in a camera where the distance measuring position can be arbitrarily selected in a photographic screen.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a camera that can arbitrarily change distance measurement within a photographic screen.

(Prior Art) Active distance measuring devices are known that measure the distance to a subject by receiving reflected light from the subject of irradiated light. With this type of device, it is normal to measure the distance to a subject located approximately in the center of the shooting screen, but if this is done, if the subject is outside the center of the shooting screen, the subject may not be in focus. Recently, various cameras have been proposed that can measure distances to arbitrary positions within the photographic screen (Japanese Patent Application Laid-Open No. 1983-1999).
184235, etc.), in this type of camera, even if the main subject is not in the center of the shooting screen but in the periphery, distance measurement is performed using the main subject located in the periphery, making it possible to focus easily. , it is not possible to accurately obtain subject brightness information, which is another necessary information for shooting.In other words, with conventional cameras, the center or central part of the shooting screen is used as the standard for subject brightness. If the distance measurement direction deviates from the center of the photographic screen, there may be a situation where distance measurement and photometry result in images being taken using information measured in different directions.

As a result, the result is a photo that is either underexposed or overexposed for the main subject.

In addition, Japanese Patent Application Laid-open No. 123368/1983 discloses a method for linking the focus detection field and the exposure measurement field, but this method uses an image sensor and is primarily for video cameras, and is not suitable for use with current film. It is unreasonable in terms of cost to apply it to cameras.

(Objective and Structure of the Invention) The present invention has been made in view of the above points, and it is an object of the present invention to obtain accurate photometric information at low cost in a camera that can arbitrarily select the distance measurement position within the shooting screen. For this purpose, a light-receiving section for detecting subject brightness is provided at or near the distance-measuring position selected by the distance-measuring device, and the exposure is controlled in accordance with the output of this light-receiving section. .

(Example) The present invention will be explained below based on the drawings.

FIG. 1 is a schematic diagram of the main parts of an embodiment of a camera according to the present invention, and in order to make the configuration easier to understand, mounting members for attaching each component are omitted from illustration.

In the figure, 1 is a photographic lens, and 2 is a photographic screen.

3 is a light projecting lens, and 4 is a light projecting LED disposed near the optical axis of the light projecting lens 3. Emitter lens 3 and receiver lens 5
are arranged apart from each other in the short side direction of the photographing screen 2 (vertical direction in the figure). In addition, the projecting LED 4 includes three LEDs 4a and 4.
consists of LEDs b and 4c, and LEDs 4a to 4C are the shooting screen 2.
are spaced apart from each other in the long side direction.

5 is a light receiving lens, and 6 is a light receiving element for distance measurement arranged near the optical axis of the light receiving lens 5. The light receiving element 6 consists of three light receiving elements 6a, 6b, and 6c, and these light receiving elements 6a
6c correspond to the LEDs 4a to 4C, and are arranged apart from each other in the long side direction of the photographing screen 2. As the light receiving elements 63 to 6c, for example, PSD (Po5ition 5e
nsitive Device) is used. P.S.
As is well known, when D receives reflected light from an object on its element surface, it outputs two currents with magnitudes corresponding to the light receiving position. The light-receiving position on the PSD is detected based on the ratio of the output currents, and the object distance is determined based on the principle of triangulation.

Reference numeral 7 denotes a photometric light-receiving element for detecting subject brightness, and 8 a photometric lens that converges light from the subject onto the photometric light-receiving element. The photometric light receiving element 7 consists of three photometric light receiving elements 7a, 7b, and 7c.
7C are arranged apart from each other in the long side direction of the photographing screen 2.

In addition, the photometric light receiving elements 7a to 7C are set such that the photometric range of the photometric light receiving elements 7a to 7C is an included angle (for example, 5'' to 10°).
~7c and the lens diameter and focal length of the photometric lens 8 are set. Furthermore, photometric light receiving elements 7a and 7b
, 7c are arranged so that their photometric directions coincide with the distance measuring directions of the LEDs 4a, 4b, and 4c, respectively, or so as to photometer the vicinity thereof. As the photometric light receiving element 7, for example, CdS (cadmium sulfide) is used.

Object brightness information can be extracted by converting it into an electrical signal.

Now, when it is desired to measure the distance to the object A, the LED 4a emits light and the light is projected onto the object AI at the distance LA, and the light receiving element 6a forms an image at the position Al'. In addition, if the object B is at a distance of 0, the image will be formed at the positions B and I on the light receiving element 6a.In this way, the image formation position of the LED image changes in the baseline direction in accordance with the object distance. The object AI is detected by detecting its position using the output of the light receiving element 6a.

The distance to B can be found.

On the other hand, when it is desired to measure the distance to the subject A2, the LED 4b is made to emit light. When light is emitted from the LED 4b to a subject A at a distance LA, the image is formed at a position A2'' on the light receiving element 6b, and if the subject B2 is at a distance of , it is imaged at a position B2° on the light receiving element 6b. The distance to the subject A t , B * is calculated based on the output of the light receiving element 6b at this time.Similarly, for distance measurement of the subject A3, when the LED 4c is lit, an image is formed at the position A3° on the light receiving element 6C. Do.Distance L
If the subject B3 is B, an image is formed at a position 83' on the light receiving element 6c. Therefore, at this time, the distances to A s and B 3 are calculated based on the output of the light receiving element 6c.

Next, the subject brightness is detected by the photometric light receiving element 7 corresponding to the distance measuring direction of the distance measuring optical system. For example, when the distance to the subject A is measured using the LED 4a and the light receiving element 6a, the brightness of the subject is detected from the output of the photometric light receiving element 7a. Similarly, when the distance to the subject A2 is measured using the LED 4b, the photometry light receiving element 7b uses the LED
When distance measurement is performed in the direction of the subject A3 using the photometer 4c, the subject brightness is detected by the photometric light receiving element 7c.

As described above, by detecting the subject brightness based on the output of the photometric light receiving element corresponding to the selected ranging direction, it is possible to obtain accurate subject luminance information according to the ranging direction.

In this case, not only the subject brightness information in the distance measurement direction but also
An appropriate exposure amount may be determined by calculating from multiple pieces of brightness information using brightness information of ambient light in directions other than the distance measurement direction.Similarly, it is also possible to perform backlight detection, for example, from multiple pieces of brightness information. .

Further, in the embodiment, the distance measurement and photometry directions are set to three directions, but the present invention is not limited to this, and it is of course possible to further subdivide the directions within the photographic screen by increasing the number of arrays.

Furthermore, in the embodiment, the base line direction of the distance measuring optical system (projection lens 3
Although an example has been shown in which the distance measurement position is changed in a direction perpendicular to the direction of the straight line connecting the distance measurement optical system and the light receiving lens 5, the present invention is not limited thereto. It can also be applied to a method of changing the method (such as Japanese Patent Laid-Open No. 60-184235). In that case, the light receiving element for photometry may be placed apart in the same direction as the direction in which the distance measurement position is changed.

Next, a second embodiment of the present invention is shown in FIG. light led
An example in which the present invention is applied to a camera having a distance measuring device using one light receiving element and one light receiving element will be shown.

In the figure, the same reference numerals as in FIG. 1 indicate the same constituent parts, and the explanation thereof will be omitted. LED for projecting light 4, light receiving element for photometry 7. The light-receiving element 6 is mounted on and fixed to a movable member 9, and the movable member 9 can move in a direction substantially perpendicular to the straight line connecting the light-emitting lens 3 and the light-receiving lens 5, that is, the base line direction. As a result, the LED for lighting
4. The photometric light receiving element 7 and the light receiving element 6 are connected to the moving member 9
As the unit moves, it moves as an integral unit in a direction approximately perpendicular to the baseline direction. The moving member 9 is attached to the camera body through two long grooves 9a using stepped screws 1O.

In FIG. 2, the movable member 9 is set at a position to measure the distance to the subject A2.

Now, the projected light from the light projecting LED 4 is reflected by the subject A2 and is received by the light receiving element 6, and the subject distance is calculated based on the output of the light receiving element 6. At this time, the subject brightness is determined by the photometric light receiving element 7. Detected by LED for lighting
4 and the photometric light-receiving element 7 are disposed on the same moving member 9, the photometric direction coincides with the distance measuring direction, and accurate subject brightness information can be obtained according to the distance measuring direction.

FIG. 3 shows a case where distance measurement is performed on a subject A. In this case, the movable member 9 is moved to the right in the figure, the light emitting LED 4 emits light toward the subject AI, and the light receiving element 6 reflects the light. The light is received, and the distance to the subject is determined from the output current of the light receiving element 6 using a known calculation method. Furthermore, when measuring the distance to the subject A3, the moving member 9 only needs to be moved to the left in the figure.The subject brightness is detected by the light receiving element 7 for photometry, and the photometry direction coincides with the distance measurement direction in any of the above cases. , accurate brightness information can be obtained. Also, the subject is A1. A
Of course, brightness information can be obtained in the same way even at a position between * and A3.

The moving member 9 is moved to a desired position using an appropriate driving means, but the method is not particularly limited and may be moved manually.Furthermore, the distance measurement position is displayed in the finder by an appropriate display means. Ru. For example, the distance measurement position can be displayed in the finder using a known method such as mechanically interlocking the display member with the moving member 9 or using an electrical display element.

(Effects of the Invention) As explained above, according to the present invention, a light receiving section is provided for detecting the luminance of a subject to be photometered at or near a distance measuring position selected by a distance measuring device, and the output of this light receiving section is By configuring the camera to obtain photometry information, it is possible to match the distance measurement direction with the photometry direction, making it possible to obtain accurate photometry information at low cost in cameras where the distance measurement position can be arbitrarily selected within the shooting screen. Obtainable.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the main parts of one embodiment of a camera according to the present invention, and FIGS. 2 and 3 are diagrams showing other embodiments. l...Photographing lens, 2...Photographing screen, 3...Light emitter lens, 4...-LED for light emitter, 5-...Light receiver lens,
6... Light receiving element, 7-... Light receiving element for photometry, 8-...
Photometric lens, 9... moving member

Claims (1)

[Claims] In a camera having a distance measuring device that can arbitrarily select a distance measuring position within a photographing screen, a light receiving section for detecting subject brightness is provided to measure the distance measuring position selected by the distance measuring device or its vicinity; A camera characterized by controlling exposure according to the output of the camera.