JPH0758366B2 - Camera rangefinder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Purpose and Field of Application] The present invention relates to a distance measuring device for a camera using a triangulation method.

(Prior art) As a range finder used in an autofocus camera, it emits a range-finding beam toward a subject, receives reflected light from the subject with a photoelectric conversion element, and measures up to the subject by a triangulation method. A distancer is used. The conventional distance measuring device based on such a triangulation method generally has a narrow distance measuring range on the screen. For example, when two persons are lined up, the distance measuring beam is generated when the center of the finder is set between the two persons. Two
It is irradiated between people, and the background of the person is in focus, resulting in incorrect distance measurement.

In order to solve such a problem, a method of arranging a plurality of light emitting elements in one row along the direction of the base line connecting the light projecting lens and the light receiving lens and arranging the light emitting element row and the light receiving element in the horizontal direction is known. U.S. Pat. No. 4,470,681 and JP-A-60-140306.
It is described in Japanese Patent Publication No.

In all of these, a plurality of light emitting elements are sequentially turned on, a subject is scanned in the horizontal direction by a distance measuring beam generated from the light emitting elements, and the position where reflected light from the subject is incident on the light receiving element is calculated to calculate the distance. Thus, it is possible to obtain a distance measuring device wider than the above-mentioned conventional example.

However, in the configuration described in the above-mentioned US Pat. No. 4,470,681, the base line length changes depending on the light emitting element that is turned on, so the distance cannot be calculated instantaneously. This tendency becomes remarkable as the number of light emitting elements increases, but if the number of light emitting elements is small, the distance measurement error increases, so it is unavoidable to increase the number of light emitting elements.
The problem of not being able to instantly calculate the distance occurs remarkably.

Further, in the configuration described in JP-A-60-140306, since the direction of the distance measuring beam is displaced from the optical axis direction of the finder, the distance measuring range cannot be displayed in the finder. That is, the distance measuring range cannot be matched between the distance measuring device and the photographing lens.

(Problems to be Solved by the Invention) In order to solve each of the problems described above, a plurality of light emitting elements are arranged in a line in a direction orthogonal to the baseline length direction, the baseline length is invariable, and the distance measuring beam and the finder are arranged. A distance measuring device in which the direction of the optical axis is matched with that of Japanese Patent Application No. 61-67459 is proposed.

In such a distance measuring device, as one condition for performing accurate distance measurement without causing a distance measuring error, the installation interval of a plurality of light emitting sources having a certain width dimension is important.

An object of the present invention is to provide a distance measuring device for a camera which can obtain high distance measuring accuracy without causing a distance measuring error by setting the arrangement intervals of a plurality of light emitting sources to appropriate values.

[Structure of Invention]

(Means for Solving the Problems) In the present invention, a plurality of light emitting sources having a width are juxtaposed with a central interval, and a distance measuring beam is emitted from these light emitting sources to a subject through a light projecting lens to measure a distance. In the range finder of the camera, the focal length of the taking lens is f ₁ , the focal length of the projecting lens is f ₂ , the width of the light emitting source is W, and the vertical dimension of the image forming screen of the taking lens is V. On this image forming screen, the height of the person of the subject located at the subject distance at which the whole body can be photographed by the photographing lens is h, the width dimension preset corresponding to this height h is K, and the center interval of the light emitting source is X. Then, the distance between the edge portions of the adjacent distance measuring beams from the light emitting sources at a position away from the light projecting lens by the subject distance is smaller than the width dimension K, and the distance measuring beam at the same position is Center interval is the width As the above modulo K, the distance X of the light emitting _{source, K · f 2 · V /} (h · f 1)
≦ X <K · f ₂ · V / (h · f ₁ ) + W.

(Operation) In the present invention, the focal length of the taking lens is f ₁ , the focal length of the light projecting lens is f ₂ , the width of the light emitting source is W, and the imaging screen of the taking lens is V in the vertical direction. Let h be the height of the person of the subject located at a subject distance that allows the whole body to be photographed by the photographing lens on the screen, K be a width dimension preset corresponding to this height h, and X be the center interval of the light emitting sources. when the center distance of the light emitting source and X, the distance X of the next fit ranging beam from each light-emitting source of a person being an object in systemic photographable object distance _{on, K · f 2 · V /} (h · f ₁ ) ≦ X <K
· F ₂ · V / so set to _{(h · f 1) + W} , between the close range which requires the most accurate ranging on the shot (up scene) to a distance systemic imaging is performed, resulting in the distance error Accurate distance measurement can be performed without any need.

(Embodiment) An embodiment of a distance measuring device for a camera according to the present invention will be described below with reference to the drawings.

First, referring to FIG. 2, the basic configuration of the distance measuring device using the triangulation means will be described.

This figure shows a so-called 35 mm camera having an image pickup surface of 36 mm in the horizontal (x-axis) and 24 mm in the vertical (z-axis), which is arranged vertically above and below the taking lens (focal length f ₁ = 40 mm) 11. Projecting lens (focal length f ₂ = 12 mm) 12 while maintaining the baseline length 1 in the z-axis direction 12
And the light receiving lens 13 is arranged. Reference numerals 14, 15 and 16 denote light emitting sources, and these light emitting sources 14, 15 and 16 oppose the light projecting lens 12 and are arranged in parallel along the x-axis direction orthogonal to the direction of the base line length l. Further, 18 is a light receiving device, and as the light receiving device 18, a one-dimensional semiconductor position detecting element is used,
It is opposed to the light receiving lens 13 and its length direction is the base line length l.
Are arranged in the z-axis direction. Then, the light receiving device 18 receives the reflected light emitted by the plurality of light emitting sources 14, 15, 16 and reflected by the subject 19 in the lateral direction. The light receiving position on the light receiving device 18 is displaced in the vertical (z-axis) direction according to the distance to the subject 19.

On the other hand, FIG. 3 shows the relationship between the plurality of light emitting sources 14, 15 and 16 and the light projecting lens 12 in an enlarged manner. Each light emitting source 14, 15 and 16 has a constant width W and has a central portion. They are arranged in a line at intervals X.
The light emitting sources 14, 15 and 16 are mounted on the lead frame flat plate 21 at a position separated from the light projecting lens 12 by the focal length f ₂ . In this case, each light source 14,15,16
LED is used, and the width dimension of the LED chip is the light source 14,1
The width W is 5,16. As shown in FIG. 4, when the step portion 21a is formed on the lead frame flat plate 21 and the LED chip is bonded inside the step portion 21a, the width W of the light emitting sources 14, 15, 16 is LE.
The opening width of the step portion 21a is larger than the width w of the D chip.

When a subject is photographed by a camera, as shown in FIG. 1, generally, the farther the subject is, the wider the depth of field (the focus range) becomes. Therefore, the closer the distance is, the higher the accuracy of distance measurement is required, but the farther the distance, the coarser the accuracy of distance measurement may be. In addition, if the size of the person who is the subject is small relative to the screen, the image of the person is absorbed by the surrounding scenery, and the image is not uncomfortable even if it is slightly out of focus. However, if the person is photographed large,
In other words, from the close-up (up-scene) to full-body shooting (when the whole body of the person is fully contained on the screen), the person is being photographed as the photographer intended, and the viewer's line of sight was also the subject. Since it is poured onto the image of a person, it must be in focus exactly.

Therefore, it is necessary to perform accurate distance measurement at least from the closest distance to the distance at which whole body imaging is performed. Therefore, the distance X between each of the light emitting sources 14, 15 and 16 for irradiating the distance measuring beams to measure the distance at a plurality of points is set as follows.

First, it is assumed that the subject is a person and the body shape is difficult to be irradiated by the distance measuring beam. That is, it is difficult for the distance measuring beam to be irradiated with an extremely thin and tall body shape, and the shooting size is as follows.

Height 180 cm, shoulder width 45.0 cm, waist (waist) width 25.0 cm.
It should be noted that a thin person naturally has a smaller lateral dimension of a subject than a fat person, and a distance measurement error is more likely to occur. Therefore, considering a thin person, the distance measurement of a fat person can be performed without any problem. Further, since the waist of the person to be photographed is located at the center in the height direction of the screen, the width of this waist becomes the preset width dimension K.

Calculating each width by height with the ratio of the above shooting dimensions,
The dimensional relationship is as follows, and a person with a wider physique (the physique of a normal person is sufficiently included) can measure the distance.

As is clear from the above values, a person with a short height has a narrow waist width (for example, a person with 150 cm has a width of 5/6 of a person with 180 cm), and the ratio of the waist width K to the height is almost constant. Here, since the distance to the subject in the whole body photographing is proportional to the height, the ratio of the waist width to the subject distance for the whole body photographing is also constant.

First, the distance necessary for taking a full body image of a person with a height h [cm], that is, from the taking lens 11 to the subject 19 shown in FIG.
The subject distance L [mm] up to is calculated by the following equation.

L = {(h / V) +1} · f ₁ (1) f ₁ : focal length of the taking lens 11 V: longitudinal size of the image formation screen In the above formula (1), h / V is more than 1 Since it is large, the following approximation holds.

L = h / Vf ₁ (1) ′ For example, when a person with a height of 180 cm is photographed, h = 1800. Therefore, substituting this into the equation (1) ′ yields the following.

L = 1800 · f ₁ / V (2) Here, when using a lens with a focal length of 40 mm with a 35 mm camera (V = 24 mm, f ₁ = 40 mm), the subject distance L is calculated from the following equation (2). Is asked.

L = 1800 × 40/24 = 3000 In other words, if you are up to 3m away, you can shoot the whole body. Of course, if the height h becomes short, the whole body can be photographed at a closer distance in proportion to the height.

Next, based on the subject distance L, the center interval X between the plurality of light emitting sources 14, 15, 16 is set so as to satisfy the following conditions shown in FIG.

In the case of whole body photography, since the waist of the subject person is located at the center in the height direction of the screen, the range-finding beam may irradiate a range narrower than the width of the waist. As shown in FIG. 1, 2
When the waist portion 19a of the subject person exists between the distance measurement beams of the two light emitting sources 15 and 16, neither of the distance measurement beams hits the waist portion 19a of the subject person. If the distance between the distance measurement beams is narrowed from this state, one of the distance measurement beams illuminates the waist portion 19a of the subject person, so that the subject distance can be detected.

Therefore, when the width of each light emitting source 14, 15, 16 is W and the interval between the central portions thereof is X, the following relationship is set from the subject distance L.

(X-W / 2) L / f 2 -WL / 2f 2 <K ...... (3) f 2: focal length K of the projection lens 12: waist (waist) Width (mm) (3) where the left side of Is the distance between the edges of the distance measuring beams from the light emitting sources 15 and 16 at the object distance L from FIG.
A waist width dimension of 250 corresponding to a height of 180 cm is substituted for the width dimension K which is set in advance for the person to be photographed, and X is set to be smaller than 250.
That is, X is obtained as follows by modifying the equation (3).

X <(250f ₂ / L) + W (3) 'Substituting equation (2) into equation (3)'.

X <(250f ₂ · V / 1800f ₁ ) + W …… (3) ″ From the formula (3) ″, for example, 35mm camera (V = 24mm)
For a lens with f ₁ = 40 mm and f ₂ = 12 mm, the dimension X is X <1.
It is calculated as 0 + W [mm]. If f ₁ becomes 35 mm, X <1.14 + W [mm] is obtained.

Next, from the viewpoint of effectively utilizing as few light emitting sources as possible, the pitch (center interval) of each distance measuring beam on the subject distance L may be 250 mm or more. That is, when the distance measurement beam has a pitch of less than 250 mm, the same person is irradiated by the two distance measurement beams. Therefore, the dimension X must also satisfy the following relationship.

(X + W / 2) L / f ₂ −WL / 2f ₂ ≧ K (4) The left side of the above equation 4 is, as is apparent from FIG. X is set so that this center interval is 250 or more in the width dimension K (waist portion width dimension) set in advance corresponding to the subject person. That is, the dimension X is obtained as follows by modifying the equation (4).

X ≧ 250f ₂ / L (4) ′ Substituting equation (2) into equation (4) ′ above.

X ≧ 250f ₂ · V / 1800f ₁ ...... (4) ″ From the above formulas (3) ′ and (4) ″, each light emitting source 1
The dimension X between the central portions of 4, 15 and 16 may be set in the range obtained by the following equation.

250f ₂ · V / 1800f ₁ ≦ X <250f ₂ · V / 1800f ₁ + W The above formula is summarized as follows.

5f ₂ · V / 36f ₁ ≦ X <5f ₂ · V / 36f ₁ + W (5) From the above formula, for example, with a 35 mm camera (V = 24 mm), f ₁ = 40
mm, f ₂ = 12 mm lens, W = 0.5 mm, the dimension X is
It may be set within the range of 1.0 ≦ X <1.5 [mm]. Also, 35
mm camera (V = 24mm), f ₁ = 35mm, f ₂ = 12mm lens, W = 0.5mm, dimension X is 1.14 ≦ X <1.64 [mm]
The range should be set to.

Further, FIG. 5 shows a state in which three distance measuring beams are emitted toward the subject and the left beam illuminates the subject. Therefore, there is incident light on the light receiving device 18 shown in FIG. 2, and triangulation is established.

And in a 35mm camera, f ₁ = 35mm, f ₂ = 12mm, W
= 0.55, the range X was set to 1.4 within the range of 1.14 ≦ X <1.69, and a live-range test of various scenes was performed, and good results were obtained for each scene.

As described above, if the subject is a person, a high ranging accuracy can be obtained without causing a ranging error at least from the up-scene to the whole-body shooting scene. Further, since the base line length is unchanged, the distance can be calculated instantly, and the distance can be measured with a margin in a time of several 100 ms until the shutter release. In particular, when the calculation is performed using a digital circuit, since the distance measurement at the point irradiated by the same distance measurement beam is repeated, the stored average value can be output as the distance measurement result, and the distance measurement accuracy is improved.

Although the above embodiment has been described with respect to the 35 mm camera, it is of course applicable to other cameras such as a video camera.

〔The invention's effect〕

According to the distance measuring device of the camera of the present invention, the distance between the adjacent distance measuring beams from each light emitting source on the subject distance at which the whole person can be photographed as the subject is set to the width dimension set corresponding to the subject person. Based on the above, the center interval of each light emitting source was set to be within the range, so from the close-up distance (up-scene), where the most accurate distance measurement is required for shooting, to the distance at which full-body shooting is performed. Therefore, accurate distance measurement can be performed without causing a distance error.

[Brief description of drawings]

FIG. 1 is a plan view of a projection system showing a main part of an embodiment of a distance measuring device for a camera of the present invention, and FIG. 2 is a perspective view showing an example of the configuration of the distance measuring device to which the same is applied. 1 is an enlarged view showing the relationship between the light emitting source and the light projecting lens in FIG. 1, FIG. 4 is a cross-sectional view showing another structural example of the light emitting source shown in FIG. 3, and FIG. 5 is the apparatus of FIG. FIG. 6 is a diagram illustrating a state in which a distance measurement beam is applied to a subject by the method. 11 …… Shooting lens, 12 …… Projector lens, 14,15,16 …… Light emitting source, 19 …… Subject.

Claims (1)

[Claims] 1. A distance measuring device for a camera, wherein a plurality of light emitting sources each having a width are arranged side by side with a central portion interval, and a distance measuring beam is emitted from these light emitting sources to a subject through a light projecting lens to measure a distance. Set the focal length of the shooting lens to f ₁ and the focal length of the projection lens to
f ₂ , the width of the light emission source is W, and the vertical dimension of the imaging screen of the photographing lens is V, and the height of the person of the subject located at a subject distance at which the whole body can be photographed by the photographing lens on this imaging screen is h. , K is a width dimension preset corresponding to the height h, and X is a center interval of the light emitting sources, the light emitting sources are adjacent to each other at a position away from the light projecting lens by the object distance. The distance between the edges of the ranging beam is
So that the distance between the center portions of the distance measuring beams at the same position is smaller than the width dimension K and is equal to or larger than the width dimension K,
Distance measurement of a camera characterized in that the distance X between the light emitting sources is set to K · f ₂ · V / (h · f ₁ ) ≦ X <K · f ₂ · V / (h · f ₁ ) + W apparatus.