JP3035374B2 - Multi-point distance measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a lens driving information output device which outputs lens driving information of a camera from a measured value of a so-called wide visual field distance measuring a plurality of positions on a photographing screen.

[0002]

2. Description of the Related Art Generally, a wide-field distance measuring method is disclosed in
As described in Japanese Unexamined Patent Publication No. 0511, a shortest distance value from a camera is selected and output as a lens drive information output from a plurality of distance measurement values. However, in such a wide-field distance measurement, since the photographer does not aim at a specific subject and measures the distance, the light is projected to a place where the projection spot projected on the subject lacks, In addition, due to the influence of stray light due to light projection, a distance measurement value is often erroneously measured to be significantly shorter or farther from a correct distance measurement result. As described in Japanese Unexamined Patent Application Publication No. 63-131019 filed by the present applicant, such a spot of a projected spot receives reflected light by a light receiving element, and the spot of the reflected light image is generated. In such a case, it is described in detail that the center of gravity of the light amount of the received light image is also moved, and the object is detected so as to be located closer to the actual position.

[0003]

However, when the above-described lens driving information output method giving priority to a short distance is applied to the conventional distance measuring apparatus, the wide-field distance measurement is originally performed.
Although it was developed in order to prevent erroneous distance measurement in a situation where the subject is as shown in Fig. 1 [1], if an algorithm that simply selects the closest distance measurement value is adopted, In the case of [2], the wrong distance measurement value (significant short distance) on the right side caused by missing spots is adopted, and there is a problem that an out-of-focus photograph is taken even though the subject is in the center. I will. In normal photographing, the probability of being in the center of the subject is 90% or more, and such erroneous ranging has a serious problem.

The above-mentioned erroneous distance measurement involves reducing the light emitting area of the light projecting element, increasing the base line length L as much as possible, fJ
Although it is reduced by reducing / fT as much as possible, in practice, it is not easy to realize due to space constraints in cameras that are becoming more compact.

An object of the present invention is to provide a camera that measures the distance of a plurality of points in a photographing screen and adjusts the focus based on the distance measurement value indicating the closest distance among the distance measurement values. It is an object of the present invention to provide a multi-point distance measuring device that outputs accurate lens driving information so that defocus does not occur due to lack of a spot despite the existence of a spot.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a multipoint distance measuring apparatus according to the present invention projects light toward the center of a photographing screen, receives reflected light from a subject, and receives the received light. A center distance detecting means for detecting a center distance corresponding to a subject distance at the center of the photographing screen from a position, projecting light toward the periphery of the photographing screen, receiving reflected light from the subject, and Peripheral distance detecting means for detecting a peripheral distance corresponding to a subject distance around the shooting screen, and all of the light projected to the vicinity of the center of the shooting screen all hit a subject having a preset width located at the center , Comparing and judging means for judging an output of the center distance detecting means or the peripheral distance detecting means and a judging distance corresponding to the vicinity of a distance where light projected to the periphery of a shooting screen does not hit the subject ;
If the comparison determination means determines that the center distance is shorter than the determination distance , the peripheral distance detection means
Light emission to the periphery of the shooting screen by the step is preset
It is said that spots are missing for subjects of wide width
A distance determination unit that drives the photographing lens by adopting the center distance in preference to the peripheral distance from the determination .

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of a multipoint distance measuring apparatus according to a first embodiment of the present invention. This multi-point distance measuring device first operates by pressing a shutter release switch SW.
A control signal is output from output terminals O1, O2, O3 of a central processing unit (CPU) 1, and a plurality of light emitting elements LR, LS,
LL emits light sequentially. The emitted light is condensed by the light projecting lens 5 into a spot-like light beam, and
It is projected on. The reflected light is received by a light receiving element (PSD) 9 via a light receiving lens 8, and the signal detected here is sent to stationary light removing circuits 10 and 11 to become signal light currents I1 and I2 excluding the steady light current. Output to the distance calculation circuit 13.
The distance to the subject 5 is measured based on the distance measurement value Ia calculated by the distance calculation circuit 13. The operation of the multi-point distance measuring device thus configured will be described.

When the control signal from the output terminal O1 of the CPU 1 is set at "H" level, the switching circuit 2
The light emitting element LL for projecting light to the subject 7a on the left side of the screen emits light. Similarly, light is emitted from the light emitting elements LS and LR, respectively.

When an "H" level signal is being output from the output terminal O4 from the CPU 1, a steady photocurrent is flowing to GND . However, when an "L" level signal is being output from the output terminal O4 from the CPU 1, a steady photocurrent is caused to flow to the ground, and at the same time, the light is generated in the PSD by the reflected light from the subject caused by the light emitted from the light emitting element LL. The signal current is output to the distance calculation circuit 13. The distance calculation circuit inputs the signal light currents I1 and I2, and outputs to the CPU 1 a distance measurement value Ia calculated by, for example, the following equation: I1 / (I1 + I2) (1). The CPU 1 calculates the distance measurement value I input to the input terminal Ia.
A is A / D converted and taken in. Therefore, the CPU 1 is informed of the distance measurement value of each A / D converted point. Next, FIG. 2 is a flowchart showing a first operation example of the distance measuring apparatus configured as described above.

First, when the shutter release switch SW is depressed, an "H" level is output from the output terminal O2 of the CPU 1, so that the light is emitted from the light emitting element LS to the subject.
At the same time, an "H" level is output from the output terminal O4 and the PSD
The signal light current is extracted from the detected photocurrent, and the center distance value calculated and output by the distance measurement calculation circuit 13 is input to the CPU 1 to perform center distance measurement for A / D conversion (step S).
1).

Next, the calculated center distance value and the predetermined distance L1
Are compared (step S2). If the center distance value is smaller than a predetermined distance L1 described later (YES), the center distance value is stored in the memory M (step S3). However, if the center distance value is larger than the predetermined distance L1 in step S2 (NO), the process proceeds to a lens drive amount calculation routine.
That is, after performing the left and right distance measurement (steps S5 and S5).
6) It is determined whether or not the left distance measurement value is closest (step S).
7) If the left distance measurement value is closest (YES), the left distance measurement value is stored in the memory (step S8). However, if the left distance value is not the closest distance (NO), it is determined whether the right distance value is the closest distance (step S9). If the right distance value is the closest distance (YES), the right distance value is determined. The value is stored in the memory (Step S10). Then, the lens driving amount is calculated based on the closest distance measurement value stored in the memory (step S4).
Next, the aforementioned predetermined value L1 will be described with reference to FIG. The predetermined value L1, the following equation is given by 2L1 tan θ-L1 / fT × t = X1 + 2 X2 ... (1).

Here, L1 is the distance from the light projecting lens to the object, t is the light emitting diameter of the light emitting element, θ is the light projecting angle, X1 is the width of the object, and X2 is the center light projecting spot is projected at the center of the object. FT: the focal length of the light projecting lens.

In FIG. 1 (b), it is preferable to project a central light projecting spot exactly at the center of the subject and set the subject distance so that the left and right projecting spots do not hit the subject. The reason why the margin is set is that the subject is not always accurately positioned at the center, and that erroneous determination is not performed even when the camera slightly shakes.

Therefore, the predetermined distance L1 for this determination may be a distance (3 to 4 m) from the distance at which the projection of light to the surroundings hits the subject to the extent that dropout can be prevented by projecting light to the periphery.

In this way, on the short distance side, there is no need to be affected by erroneous distance measurement due to lack of left and right spots.
However, on the long distance side, if a spot is missing, the amount of reflected light itself is reduced, making detection impossible, and as a result, a short distance shift due to the spot missing does not occur. Therefore, multipoint ranging that is resistant to erroneous ranging such as missing spots can be achieved in total.

Next, a distance measuring apparatus according to a second embodiment will be described. The distance measuring apparatus of the second embodiment has the same configuration as that of the first embodiment, and differs from the distance measuring process. Therefore, the configuration will be described with reference to FIG.

The processing steps of distance measurement will be described with reference to the flowchart of FIG. Here, A, B, C, and D described in the flowchart of FIG. 3 respectively show views of the arrangement of the subject in FIG. 3B as viewed from above, and similarly, (1), (2), and
(3) shows an example of each of the arrangements of the subject shown in FIG. 4 when viewed from above. Each arrow in FIG. 4 indicates a spot to be focused. Further, FIG.
(B) shows the positional relationship of spots due to spot missing. First, the center, left, and right distances are measured (step S
11, S12, S13). Obtained distance values MS, M
L and MR are stored in the memory (step S14).

Next, the center distance value MS is compared with the center distance value M L , MR (step S15), and the center distance value MS is calculated.
Is smaller (YES), the center distance value MS is stored in the memory M.
Is stored (step S16). That is, (1) if both of them are far from the center, the center distance measurement value MS is stored in the memory M (step S15). This is Figure 5
This is an improvement in spot chipping shown in FIG.

Next, at step S15, one of the distance measurement values M
If any of the values L and MR is larger than the central distance value MS (NO), it is determined whether the distance values ML and MR are substantially equal to the central distance value MS (step S17). If the measured values MS and MR are almost equal in this judgment, (Y
ES), the closest value is compared with the distance L1 (step S19), and if the closest value is smaller than the distance L1, the process proceeds to step S16. However, if the closest value is larger than the distance L1 in step S19, the closest value is stored in the memory (step S20), and the process proceeds to step S21.
That is, (2) there is one with the same distance as the center,
If the closest value is longer than the distance L1, it is determined that the object is to be prevented from missing, and the closest value is stored in the memory M. If the distance is close, the center distance value is stored in M. This is an improvement over the spot chipping shown in FIG.

However, if any one of them is not equal in step S17 (NO), the center distance measurement value MS becomes equal to the distance measurement value M.
It is determined whether it is larger than S, MR (step S1).
8). In this determination, the center distance measurement value MS becomes the distance measurement values ML and MR.
If it is larger (YES), the process proceeds to step S19, and if smaller (NO), the process proceeds to step S16. That is, (3) when the center is the farthest, if the closest value is farther than the distance L1, it is determined that the object is not to be skipped, and the closest value is stored in the memory M; Store. Next, the lens driving amount is calculated based on the distance measurement value stored in the memory M (step S21).

Next, the flowchart of FIG. 6 shows a third embodiment in which the center value in the distance measuring apparatus shown in FIG. Is a distance measuring device that prevents the disadvantage of being selected. The distance measuring apparatus of the third embodiment has the same configuration as that of the first embodiment, as in the second embodiment, and a description thereof will be omitted.

First, the center, left, and right distances are measured (steps S31, S32, and S33). Each obtained distance value MS,
ML, MR and the light amount values KS, KL, KR are stored in the memory, respectively (step S14). Next, FIG.
As shown in the processing step, the center distance value MS and the distance values ML , M
By comparing the large and small values of R, the nearest value or the center distance value selected by the determination is stored in the memory M (step S3).
5 to Step S40).

Next, a comparison is made between (left distance measurement value) ² × (left light amount value) and (center distance measurement value) ² × (center light amount value) to determine whether or not a spot at the center is missing. (Step S41). If spot missing has occurred in this determination (NO), the central value is set to, for example, a normal focal length of 3 to 4 m (step S42), and the process returns to step S35 to perform the processing again. If spot missing does not occur (YE
S), a lens driving amount is calculated based on the distance measurement value stored in the memory M (step S43).

Here, when the re-processing is performed by setting the ordinary focal length to 3 to 4 m, it is determined that the spot is missing when the amount of reflected light is small even if the result of the center distance measurement is very close , So
To prevent the lens from being driven based on the measured distance
In order to

The method for measuring the amount of light described above is described in Japanese Patent Application No. 2-172499 filed by the present applicant. However, since the method for measuring the amount of light is not a requirement of the present invention, its description is omitted. Omitted.

As described in detail above, the multipoint distance measuring apparatus of the present invention prevents erroneous distance measurement due to missing light spots or stray light generated by a plurality of light projections on a subject, and reduces the distance between central distance measurement points. It is effective in preventing hollowing out without lowering the focusing rate. In addition, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications and applications are possible without departing from the spirit of the invention.

[0028]

As described above, the multipoint distance measuring apparatus of the present invention measures the distance of a plurality of points in a photographing screen and adjusts the focus based on the distance value indicating the shortest distance among the distance values. In a camera to be performed, it is possible to output accurate lens drive information so as to prevent out-of-focus due to missing spots even though the subject exists at the center.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a multipoint distance measuring apparatus according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of the distance measuring apparatus shown in FIG. 1;

FIG. 3 is a flowchart illustrating a distance measuring process of the distance measuring apparatus according to the second embodiment.

FIG. 4 is a diagram illustrating an example of each arrangement of a diagram of the arrangement of a subject as viewed from above;

FIG. 5 is a diagram showing a state of a spot lacking a light projected on a subject.

FIG. 6 is a flowchart showing a distance measuring process of the distance measuring apparatus according to the third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Central processing unit (CPU), 2, 3, 4 ... Switching circuit, 5 ... Projection lens, 6 ... Multi-point distance measuring circuit, 7 ... Subject, 8 ... Light receiving lens, 9 ... Light receiving element (PSD), 10 ,
11: steady light removal circuit, 13: distance calculation circuit, SW: shutter release switch, O1, O2, O3 ... output terminals, LR,
LS, LL: Light emitting element.

Claims (6)

(57) [Claims] 1. A center distance detecting means for projecting light near the center of a photographing screen, receiving reflected light from a subject, and detecting a center distance corresponding to a subject distance at the center of the photographing screen from the light receiving position. Peripheral distance detecting means for projecting light toward the periphery of the photographing screen, receiving reflected light from the subject, and detecting a peripheral distance corresponding to a subject distance around the photographing screen from the light receiving position; All light emitted near the center of the shooting screen is located in the center .
A distance corresponding to the vicinity of a distance where the light projected to the periphery of the shooting screen does not hit the subject, and the output of the center distance detecting means or the peripheral distance detecting means. Comparison judgment means for comparison judgment
And when the comparison determination means determines that the center distance is shorter than the determination distance , the peripheral distance detection
Light projection toward the periphery of the shooting screen by the emitting means is preset
Spots are missing for subjects with different widths
And a distance determination unit that drives the photographing lens by adopting the center distance in preference to the peripheral distance. 2. The method according to claim 1, wherein the distance determining unit includes the comparing and determining unit.
When the detection result of the center distance by the center distance detection means is determined to be shorter than the determination distance,
2. The multi-point distance measuring apparatus according to claim 1, wherein in the case, the photographing lens is driven by using the center distance without performing detection by the peripheral distance detecting unit. Wherein the peripheral distance detecting means is detectable for at least two directions, the distance determining means, said
By the comparing and judging means, the central distance is not the shortest distance, and any one of the peripheral distances and the central distance are about the same distance, and the closest distance is a medium to short distance than the judgment distance. The multi-point distance measuring apparatus according to claim 1, wherein when it is determined that the photographing lens is driven using the center distance. 4. An active distance measuring means for measuring a central distance near the center of the photographing screen and a peripheral distance in at least two directions around the photographing screen, and the closest distance among the plurality of distance measuring values. In a multi-point distance measuring apparatus for selecting a distance and driving a photographing lens based on the shortest distance, a central projection by the active distance measuring means to the periphery is provided.
The light shines all over the subject of the preset width located in the center.
Light hits around the shooting screen
Corresponding to the vicinity where the light does not hit the subject
Comparing the judgment distance with the closest distance, and when the closest distance is closer than the judgment distance, driving the photographing lens based on the center distance; Distance device. 5. The method according to claim 4, wherein the comparison between the determination distance and the shortest distance is performed when any one of the peripheral distances and the center distance are substantially equal to each other.
The multi-point distance measuring device according to 1. 6. The multipoint ranging according to claim 4, wherein the comparison between the determination distance and the shortest distance is performed when a center distance is the longest among the plurality of distance values. apparatus.