JPH03196031A - Range-finder for camera - Google Patents

Abstract

PURPOSE:To perform consecutive range-finding from infinity to the shortest distance in the case of macro photographing by making a reflected light beam from an object which is projected by a 1st light source incident on a photodetector in the case of normal photographing and making a reflected light beam from the object which is projected by a 2nd light source incident on the photodetector in the case of macro photographing respectively. CONSTITUTION:By taking the intersection of the light beam projected by the 2nd light source 14 with the optical axis 17 of a light receiving lens 16 as a boundary between the normal photographing and the macro photographing, the reflected light beams from the object which are projected from the 1st light source 11 and the 2nd light source 14 are made incident on the light receiving device 15 in the case of the normal photographing and in the case of the macro photographing respectively. As a result, in the case that the photodetector 15 does not receive the reflected light beam from the object when the 1st light source 11 emits the light, it is because the reflected light beam from the object is faint or because it is out of the light receiving surface of the light receiving device 15. When the 2nd light source 14 is allowed to emit the light continuously and the reflected light from the object is made incident on the photodetector 15 after turning off the 1st light source 11, range-finding is performed to the object in a macro photographing area. At such a time, the action of range-finding in the infinity is started in the case that the light is not made incident on the photodetector 15. Thus, the consecutive range-finding is performed from the infinity to the shortest distance where the macro photographing can be possible.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a distance measuring device for measuring the distance to a subject for a photographic camera.

"Prior Art" Cameras are widely known that are equipped with a distance measuring device that receives reflected light from light projected onto a subject and measures the distance to the subject using a light projection angle or a light reception angle.

This type of camera is equipped with a so-called autofocus mechanism that moves the photographing lens to a focusing position in accordance with a distance measurement signal.

In addition, many of these cameras have a macro photography function, so you can shoot from infinity to short distances (e.g. oo~1m).
The distance measurement can be switched between normal photography, which targets a subject, and macro photography, which targets a subject that is even closer than the short distance (for example, 1 m to 0.5 m).

Specifically, for distance measurement in macro photography, a wedge-shaped prism is inserted in front of the light source to change the light emission path, and the light emission or reception lens is moved in a direction perpendicular to the optical axis. There are some configurations in which the light receiving surface of the light receiver is divided into areas for distance measurement for normal photography and distance measurement for macro photography, and the light area is switched.

In addition, as a camera that does not require switching, there is also a camera q that has a configuration in which the width of the light-receiving surface of the light receiver is made longer so that distance measurement can be performed continuously regardless of whether normal or Mac L photography is being performed.

``Problem to be solved by the invention'' The above-mentioned camera using a wedge-shaped prism requires mechanical performance to move the prism forward and backward. It is not possible to measure the distance visually, and on top of that, power is required to operate the mechanical mechanism.

Furthermore, even if the wedge-shaped prism is moved forward and backward by manual operation, a warning device or the like must be provided in addition to the switching operation device.

The above-mentioned camera that moves the light projecting lens or the light receiving lens has a mechanical structure for moving these lenses, and therefore has the same problem as above.

Cameras equipped with a light receiver with a light-receiving surface that is divided into distance measurement for normal photography and distance measurement for macro photography have weak output current from the light receiver, making it difficult to control the movement of the photographic lens in response to the distance measurement signal. , the configuration of the amplification stage of the control circuit becomes complicated.

Cameras that enable distance measurement for normal photography and macro photography by increasing the width of the light-receiving surface of the photoreceptor have a photodetector that is an expensive component and is easily affected by noise, so the distance measurement signal is It is difficult to operate the processing circuit stably.

In view of the above-mentioned circumstances, it is an object of the present invention to develop a camera distance measuring device that is capable of continuous distance measurement from infinity to the shortest distance for macro photography, and that operates stably without requiring any mechanical operating mechanism. shall be.

"Means for Solving the Problems" In order to achieve the above-mentioned objects, the present invention emits light onto a subject and receives the reflected light to obtain a triangular 8I! In a camera distance measuring device configured to perform an I amount, a first light source emits light in the optical axis direction of a light projecting lens, and disposed near the first light source,
a second light source emitted from the light emitting lens at a certain angle with respect to the optical axis of the light emitting lens; and a second light source emitting light from the light emitting lens parallel to the optical axis of the light emitting lens at a predetermined distance. A light receiving lens having an optical axis intersecting with the light receiving lens, and a light receiver receiving light through the light receiving lens, and the intersection between the light emitted from the second light source and the optical axis of the light receiving lens is used as the boundary between normal photography and macro photography. The camera measuring device is characterized in that in normal photography, the light reflected from the subject by the light emitted by the first light source is incident on the light receiver, and in the case of macro photography, the light reflected by the subject by the light emitted by the second light source is incident on the light receiver to measure the distance. We propose a range device.

"Function" In normal photography, the light emitted from the first light source is projected in the optical axis direction of the light projecting lens, and the reflected light from the object enters the light receiver at a predetermined angle with respect to the optical axis of the light receiving lens.

In macro photography, the light emitted from the second light source is projected at a predetermined angle with respect to the optical axis of the light projecting lens, and the reflected light from the object enters the light receiver at a predetermined angle with respect to the optical axis of the light receiving lens.

As a result, if the light receiver does not receive the reflected light from the subject when the first light source emits light, either the reflected light from the subject is so weak that it does not reach the light receiver, or it is off the light receiving surface of the light receiver.

Therefore, after turning off the first light source 11, the second light source 11 is turned off.
When the light source emits light and the reflected light from the subject enters the receiver, the distance to the subject in the macro photography area is measured, and at this time,
If there is no incident light on the receiver, it moves on to operations such as infinite distance measurement.

``Example'' Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a simple configuration diagram showing a distance measuring device according to the present invention, and 11 is a first light source using a light emitting element such as an LED, which emits light in the direction of the optical axis 13 of a light projecting lens 12. It is arranged as follows. Reference numeral 14 denotes a second light source made of a similar light emitting element, and the light emitted from this second light source 14 is projected through a projection lens 12.
It is arranged so that it has an angle of .

Note that the first light source 11 and the second light source 14 are provided adjacently,
The light emitted from these lights is condensed by a light projection lens 12 and projected as a beam of light in front of the camera.

Reference numeral 15 denotes a light receiver composed of a photoelectric conversion element such as a CCD or PSD, and is arranged to receive the reflected light from the object focused by the light receiving lens 16.

The light receiving lens 16 has its front axis 17 connected to the light projecting lens 16.
The optical axis 13 is arranged so as to be parallel to the optical axis 13 at a distance apart from each other.

Further, the second light source 14 is connected to the optical axis 17 of the light receiving lens 16.
The point P where the projected lights intersect is the closest distance in normal shooting. How is the distance interval L, the first light source 11 and the second light g
A distance interval Q of 14 is appropriately determined.

On the other hand, 18 is a distance measurement calculation circuit, and 19 is a driver circuit. These circuits 18 and 19 receive a ranging start signal S1 and a switching signal S2 as execution commands from the microprocessor 21 which is activated when the switch 20 is opened.

Further, the distance measurement calculation circuit 18 enters an operating state in which it inputs the distance measurement start signal S and receives the light reception output S3 of the light receiver 15, and also sends an opening signal S to the driver circuit 19.

The driver circuit 19 inputs the drive signal S4 and receives the switching signal S
2. Make the light source emit light according to 2. Note that the switching signal S2
is a signal for switching from the light emission mode of the first light source 11 to the light emission mode of the second light source 14.

When the microprocessor 21 receives the distance measurement signal S0 from the distance measurement calculation circuit 18, the motor drive circuit 22 is operated by the focus detection signal Ss output from the microprocessor 21.

The motor drive circuit 22 drives the motor 23 in response to the focus detection signal S5, and moves the photographic lens 24 to the in-focus position.

Next, the operation of the distance measuring device described above will be explained.

a. The distance measurement driver circuit 19 for normal photography receives the moving signal S, and causes the first light source 11 to emit light.

The light emitted from the first light source 11 is focused by the projection lens 12 and projected in the direction of the optical axis 13 .

At this time, if the object is located at a distance greater than or equal to the closest distance D+1, the reflected light is collected by the light receiving lens 16 and enters the light receiver 15. For example, closest distance.

When there is a subject at the light receiving surface position 15a of the light receiver 15
The image of the subject is formed.

From this, the distance measurement calculation circuit 18 receives the light receiving output S of the light receiver 15.
, is input and calculated, and the ranging signal S0 is transmitted to the microprocessor 21.

From then on, as already explained, this microprocessor 2
The photographic lens 24 is moved to the in-focus position in accordance with the focus detection signal S output by the lens 1.

In the distance measurement for normal photography described above, if the reflected light from the subject does not enter the light receiver 15, that is, the reflected light from the subject is weak and does not reach the light receiver 15, or the reflected light from the subject enters the light receiving lens 16 at a large angle and is received. When the light-receiving surface of the device 15 is removed, the microprocessor 21 outputs a switching signal S2 based on the state of the light-receiving output S at this time.

b. The distance measurement driver circuit 19 for macro photography inputs the switching signal S, turns off the first light source 11, and turns on the second light source 14.

The light emitted from the second light source 14 is focused by the projection lens 12 and projected toward point P.

At this time, the subject is at the closest distance. and shooting limit ratio itD
If the light exists between the beams and the beam, the reflected light is focused by the light receiving lens 16 and enters the light receiver 15.

For example, when the subject exists near the closest distance D0, the object is located near the light receiving surface position 15b of the light receiver 15.

If a subject exists within the photographing limit distance 1t/& Dx, the respective subject images are formed at the light-receiving surface position 15a.

From this, the distance measurement calculation circuit 18 that inputs the light reception output S□ at this time is the distance measurement signal S for macro photography.

is calculated and transmitted to the microprocessor 21. Thereafter, the photographing lens 24 is moved to the in-focus position in the same way as distance measurement for normal photography.

C5 Infinity distance measurement During distance measurement in normal photography and macro photography, when the reflected light from the subject is not input to the light receiver 15, the distance measurement calculation circuit 18 adjusts the distance to infinity based on the state of the light reception output S3 at that time. The distance measurement signal S, , is transmitted to the microprocessor 21. As a result, the microprocessor 21 moves the photographic lens 24 to focus on infinity.

Note that if the subject exists at a position closer than the photographing limit distance D, the reflected light from the subject deviates from the light-receiving surface of the light receiver 15 and therefore does not enter the light receiver 15. Therefore, in this case, the photographing limit is reached, but since the photographing lens 24 is focused at infinity as described above, it is unreasonable, so the second light source 14 is connected to the first light source 11 to emit light. However, if the light receiver D15 does not receive the reflected light, it is possible to move the photographing lens 24 to a predetermined position based on the state of the light reception output S3 at this time, so that the photographing can be performed without regard to focusing. preferable.

The first light source 11 and the second light source 14 shown in this embodiment may be arranged separately, but as shown by way of example in FIG.
It can be configured as a pair of light sources within one.

Furthermore, regarding the camera equipped with the distance measuring device of this embodiment,
It is convenient to configure the target frame 40 in the finder as shown in FIGS.

Note that FIG. 3 shows a range where spot light is projected during distance measurement in normal photography, and FIG. 4 shows a range where spot light is projected during distance measurement in macro photography.

As shown, the target frame 40 is offset in one direction with respect to the finder center line 41.

With this configuration, in normal shooting, the closest distance D
The spot light projection position of the subject existing at 0 becomes as shown by the dotted line N1 in Fig.
The spot light projection position of the object existing at 0 becomes as shown by the dotted line M1 in FIG.

Note that the double-dot chain uN2 shown in FIG.
The two-dot chain lines M2 shown in the figure each represent the spot light projection position of the subject existing at the photographing limit distance D1.

"Effects of the Invention" As described above, the distance measuring device according to the present invention can continuously measure a range from infinity to the shortest distance that allows macro photography, and furthermore, the mechanical configuration is without needing
Since it can be configured with a simple optical system and electric circuit, it has high ranging accuracy and is suitable for mass production and low production costs.

[Brief explanation of drawings]

FIG. 1 is a simplified configuration diagram of a distance measuring device showing an embodiment of the present invention, and FIG. 2 shows a first light source and a second light source provided in the distance measuring device.
3 and 4 are explanatory diagrams showing the relationship between the target frame provided in the camera finder and the spot light projection position of the subject. It is. 11...First light source 12...Light emitting lens 13...Optical axis of the light emitting lens 14...Second light source 15...Light receiver 16...Light receiving lens 17...Light from the light receiving lens Axis 18...Distance calculation circuit 19...Driver circuit 21...Microprocessor 22...Motor drive circuit 23...Motor 24...Photographing lens

Claims (1)

[Claims] In a camera distance measuring device configured to perform triangulation by projecting light onto a subject and receiving the reflected light, there is provided a first light source that projects light in the optical axis direction of a projecting lens, and a distance measuring device disposed near the first light source. , a second light source that is projected from the light projecting lens at a certain angle with respect to the optical axis of the light projecting lens; It is equipped with a light-receiving lens having an optical axis that intersects with the light, and a light-receiving device that receives light through the light-receiving lens. , for a camera, characterized in that in normal photography, the light reflected from the subject by the light emitted by the first light source is incident on the light receiver, and in macro photography, the light reflected by the subject by the light emitted by the second light source is incident on the light receiver to measure the distance. Ranging device.