JPH06100462B2 - Ranging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a triangulation type distance measuring device used in an autofocus camera.

(Prior Art) Conventionally, as a distance measuring device used for an autofocus camera, infrared light is radiated toward a subject, reflected light from the subject is received by a photoelectric conversion element, and the distance between the subject and the subject is determined by a triangulation method. The one that measures the distance is used. With this method,
It is common to collect infrared light so that the distance can be measured as far as possible.

However, the range of distance measurement on the screen is narrow because the infrared light is collected. For example, when two people are lined up, if the center of the finder is placed between the two people, the infrared light will be 2
It is irradiated between people, and the background of the person is in focus, resulting in incorrect distance measurement. Various means for expanding the range-finding range on the screen to solve such a problem are known.

For example, as described in U.S. Pat. No. 4,470,681, there is known a configuration in which imaging lenses for an infrared light emitting diode and a light receiving element are connected to each other and horizontally movable. That is, these lenses are moved at the same time in a state where the two lenses for projecting light and for receiving light are focused on the same point, and this is a method of scanning the object surface by infrared light. In addition, there is also described a technique in which each of the imaging lenses for the infrared light emitting diode and the light receiving element is formed into a lens array that is a compound eye, and the distance is measured as many points as there are lens arrays.

Further, as described in Japanese Patent Laid-Open No. 59-193406, a light source is rotated to perform scanning, but a diffraction grating is arranged in front of the light source and a main beam of 0th order is emitted. First-order diffracted beams are generated on both sides, and the object surface is scanned by these three beams.

Then, as described above, both the imaging lenses are horizontally moved or the light emitting source is rotated, so that the object surface is scanned in either case, thereby enabling multi-point distance measurement.

However, the provision of such a movable part has a problem in durability, and the accuracy may be lowered.

Further, the method using the lens array has a troublesome problem that the optical axes of the lens arrays of the light emitting section and the light receiving section must be aligned. Furthermore, if a lens array is used, the distance measuring section becomes large, which imposes a great restriction on the camera design.

Therefore, as described in, for example, Japanese Patent Laid-Open No. 60-60511, infrared rays are emitted from a plurality of light emitting sources in different directions in the left and right directions of the screen, and the nearest portion is measured as a subject distance. The composition is also known.

(Problems to be Solved by the Invention) However, as described in Japanese Patent Application Laid-Open No. 60-60511, when the distance of the closest part of the distance measurement from a plurality of light emitting sources is used as the distance measurement value. For example, when there is a portion closest to the periphery of the screen, the peripheral portion is focused, and the central portion is out of focus, which causes a problem that the entire screen is out of focus.

The present invention has been made in view of the above problems, and is a multi-point distance measuring device that measures a wide range without using a movable part or a lens array and prevents out-of-focus at least in the center of the screen. The purpose is to provide.

[Structure of Invention]

(Means for Solving Problems) According to the present invention, a light source for irradiating a subject with infrared light and a light source for receiving reflected light from the subject are arranged with a baseline length maintained. The camera body is provided with a one-dimensional semiconductor position detecting element whose electric output changes according to the change of the light receiving position along the base line length direction, and the distance to the object is measured based on the output of the one-dimensional semiconductor position detecting element. In the distance measuring device, triangulation means composed of the light emitting source and the one-dimensional semiconductor position detecting element are arranged above and below the front surface of the camera body, and the light emitting source irradiates the central portion of the screen with light emission. Firstly, a plurality of light emitting elements that are arranged in parallel to the light emitting element in a direction orthogonal to the base line length direction and illuminate the left and right of the central portion of the screen by light emission, and a light emitting element that illuminates the central portion. Departure Light is emitted, the light emitting elements are sequentially emitted from the side closer to the light emitting element located in the center, distance measurement is performed for each light emission of these light emitting elements, and it is determined whether or not the distance measurement result is a finite distance. And a control means for setting the distance to the subject based on the measured distance value of the finite distance.

(Operation) The present invention irradiates with a plurality of light emitting elements, distance-measures the distance to the object based on the output of the one-dimensional semiconductor position detecting element, and firstly, causes the light emitting element in the central portion to emit light to center the screen. If the distance measurement result is not a finite distance, the light emitting elements adjacent to the center of the screen are sequentially emitted until the first finite distance is obtained, and the distance is measured at least in the center of the screen. Prevents out-of-focus areas.

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

FIG. 1 shows the configuration of the triangulation means, 11 is a light projecting lens, 12 is a light receiving lens, and the light projecting lens 11 and the light receiving lens 12 are arranged with a base line length 1 maintained. Further, a light receiving source 13 is arranged so as to face the light projecting lens 11 with a distance f1 therebetween, and a plurality (n) of light sources 13 are juxtaposed along the x-axis direction orthogonal to the direction of the base line length l. It has a light emitting element, for example, infrared light emitting diodes IR1, IR2, ..., IRn. Further, a one-dimensional semiconductor position detecting element (one-dimensional PSD) 14 is arranged so as to face the light receiving lens 12 with a distance f2 maintained,
The one-dimensional semiconductor position detecting element 14 is arranged in the length direction along the y-axis direction along the base line length l.

Further, 15 is a subject, and each optical axis represents the irradiation light to the subject 15 at each position N, M, F and the reflected light from the subject 15, and each reflected light passes through the light receiving lens 12 and is a one-dimensional semiconductor. The light is received at each position on the y-axis of the position detection element 14. In this case, multiple infrared light emitting diodes IR1, IR2, ..., I
When the light emitted from Rn is reflected by the subject 15 at the same position, for example, the position M, it forms a line on the one-dimensional semiconductor position detecting element 14 at the same position on the y axis in the width direction (x axis). To form an image.

Then, the one-dimensional semiconductor position detecting element 14 has a length direction (y
The electric outputs (electrical outputs ΔI1 and ΔI2 shown in FIGS. 3 and 4) change according to changes in the light receiving points along the axis. The electric output does not change with respect to the change of the light receiving point in the width direction (x axis).

FIG. 2 is a plan view of the triangulation means shown in FIG. 1 as seen from above, FIG. 3 (a) also shows the triangulation means from the side, and FIG. 3 (b) is a one-dimensional semiconductor. Position detection element 14
The reflected light for each of the positions N, M, and F imaged above is shown.

FIG. 4 shows a control circuit of the above-described triangulation means, 20 is a microcomputer, and this microcomputer 20 controls the whole, and a lighting circuit 21 controlled by this microcomputer 20 is provided. Lighting circuit
In response to an instruction from the microcomputer 20, a reference numeral 21 causes a corresponding one of the plurality of infrared light emitting diodes IR1, IR2, ..., IRn to emit light.

Reference numeral 23 denotes a distance calculation circuit, which receives the electric outputs ΔI1 and ΔI2 from the one-dimensional semiconductor position detection element 14 and calculates the distance to the subject by a predetermined calculation method. Then, the calculated result is output to the microcomputer 20 as an m-bit digital signal.

Further, 24 is a light emission selection means, and this light emission selection means 24 has switches SW1, SW2, ..., SWn provided corresponding to the infrared light emitting diodes IR1, IR2 ,. Infrared light emitting diodes IR1, IR2, ..., IRn corresponding to the ON operation of SW1, SW2, ..., SWn (for example, switch SW1
Corresponds to the infrared light emitting diode IR1. ) Is applied to the microcomputer 20 to give a selection signal. Based on this selection signal, the microcomputer 20 causes the corresponding infrared light emitting diodes to emit light one by one. If all the switches SW1, SW2, ..., SWn are off,
The microcomputer 20 is set so that only the infrared light emitting diode located in the central portion emits light.

Further, 25 is a distance calculation instruction switch, and this distance calculation switch 25 gives the microcomputer 20 a shortest value selection command in its ON state and an average value calculation command in its OFF state. That is, the distance calculation circuit 23 calculates the distance to the subject each time one of the infrared light emitting diodes IR1, IR2, ..., IRn emits light, and outputs it as an m-bit digital signal. Stores these, and if the shortest value selection command is given by the ON state of the distance calculation instruction switch 25, the shortest value is selected from these. On the other hand, if the average value calculation command is given by the OFF state of the distance calculation instruction switch 25, the average value of each value described above is calculated. The shortest value or the average value thus obtained is output to the lens drive circuit 26 as an m-bit digital signal. The lens drive circuit 26 drives the photographing lens 27 to the in-focus position based on the input data.

Further, 28 is a start instruction switch, and this start instruction switch 28 gives an instruction to the microcomputer 20 to execute each of the above-mentioned functions when turned on.

FIG. 5 shows an autofocus camera in which the above-described triangulation means is incorporated in the camera body 30. The projection lens 11 is the camera body
At the bottom of the front of 30 and the receiving lens 12 is the camera body 30
It is provided on the upper part of the front of the. That is, although not shown, triangulation means composed of a light emitting source 13 and a one-dimensional semiconductor position detecting element 14 facing the light projecting lens 11 and the light receiving lens 12 are arranged above and below the front surface of the camera body 30. Therefore, the plurality of infrared light emitting diodes IR1, IR2, ..., IRn forming the light emitting source 13 are juxtaposed in the horizontal direction orthogonal to the base line length l of the triangulation means.

Next, the operation of the above embodiment will be described.

For example, as shown in FIG. 6, an operation for photographing a subject in which two persons located relatively close to each other and a distant background are photographed will be described.

In this case, first, the switches SW1, SW2, ...
…, Keep all SWn on. Further, since it is necessary to focus on two persons located at a short distance, the distance calculation instruction switch 25 is turned on and the shortest value selection command is given. When the start instruction switch 28 is turned on in this state, the lighting circuit 21 causes the plurality of infrared light emitting diodes IR1, IR2 ,.
Rn is emitted sequentially.

Here, first, when the infrared light emitting diode IR1 emits light,
The infrared light is applied to the subject through the light projecting lens 11 shown in FIG. When this infrared light is applied to a person on the left side of the figure as shown in FIG.
Through 12, the image is formed at a predetermined position on the one-dimensional semiconductor position detecting element 14 corresponding to the distance to this person.

Then, the electric outputs ΔI1 and ΔI2 corresponding to the image forming positions are generated, and the distance calculation circuit 23 calculates the distance to the subject based on the electric outputs ΔI1 and ΔI2, and outputs it to the microcomputer 20 as m-bit data. Next, when the second infrared light emitting diode IR2 emits light and the same person is irradiated with the infrared light as shown in FIG. 6, the reflected light on the one-dimensional semiconductor position detecting element 14 is connected in the y-axis direction. The image position is the same, and the distance calculation circuit 23 outputs the same m-bit data as the previous time. Further, when the third infrared light emitting diode IR3 emits light and the infrared light passes between the persons as shown in FIG. 6, the distance calculation circuit 23 outputs m-bit data representing infinity. In this way, the nth infrared light emitting diode IRn
The above operation is repeated until lights up.

Further, m-bit data is stored in the microcomputer 20, and all the infrared light emitting diodes IR1, IR2, ...
.., IRn, when the light emission is completed, the shortest value, that is, the data corresponding to the distance to the person in FIG. 6 is selected from these m-bit data and output to the data lens drive circuit 26. Therefore, the photographing lens 27 is driven to the in-focus position for the person in FIG. Of course, depending on the subject, the average value may be preferable rather than the shortest value. In this case, the distance calculation instruction switch 25 may be turned off.

Then, turning on and off the light emission selecting means 24 is a lens for photographing.
The distance measurement zone may be narrowed as the focal length becomes longer by linking with the focal length of 27. That is, in this way, it is possible to reliably measure the distance to a distant place.

Further, a program for automatically controlling the light emission of the plurality of infrared light emitting diodes IR1, IR2, ..., IRn in accordance with a predetermined order and setting the distance to the microcomputer 20 is set without providing the light emission selecting means 24 in FIG. You may.

For example, as shown in FIG. 7, first, the infrared light emitting diode provided in the center of the distance measuring zone is caused to emit light to measure the distance (step 1). If the distance measurement value is infinite, the distance measurement is gradually performed. Expand the range (steps 2A-6). Then, if the distance measurement value is infinite until the end, the lens 27 for photographing is driven to the infinite position. Of course, if the distance measurement value does not become infinity on the way, it is determined that the distance to the subject has been measured, and the lens is driven by the distance measurement value (step 6).

Even with such a configuration, in the case of the subject shown in FIG. 6, the person can be focused, and the background is not focused.

〔The invention's effect〕

According to the distance measuring device of the present invention, it is possible to perform multi-point distance measurement without using a movable part or a compound eye lens, there is no distance measurement error, and durability is excellent. Since the light emitting elements adjacent to the central portion of the screen are sequentially made to emit light until the finite distance is first obtained, distance measurement is performed, so that the defocused screen can be eliminated at least near the central part of the screen.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a distance measuring device according to the present invention, FIG. 2 is a plan view of the same as above, FIG. 3 is a side view of the same as above, and FIG. 4 is a block diagram showing a distance measuring control circuit above. 5 is an external view of the camera of the same as above, FIG. 6 is a view showing the inside of the finder at the time of distance measurement, and FIG. 7 is a flow chart for explaining the operation of another embodiment of the same as above. 13 ... Emission source, 14 ... One-dimensional semiconductor position detection element, 15 ...
… Subject, 30 …… Camera body, IR1, IR2, ……, IRn …… Infrared light emitting diode as light emitting element, l …… Base line length.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G02B 7/32 G03B 13/36

Claims (1)

[Claims] 1. A light emitting source for irradiating an object with infrared light, and a light emitting source arranged to maintain a baseline length with respect to the light emitting source so as to receive reflected light from the object, and a change in light receiving position along the baseline length direction. A one-dimensional semiconductor position detecting element whose electric output changes according to the camera body, and a distance measuring device for measuring a distance to a subject based on the output of the one-dimensional semiconductor position detecting element, Triangulation means consisting of the one-dimensional semiconductor position detecting element are arranged above and below the front surface of the camera body, and the light emitting source irradiates the central portion of the screen by light emission, and with respect to this light emitting element A plurality of light emitting elements which are juxtaposed in the direction orthogonal to the baseline length direction and which illuminate the left and right of the central portion of the screen by light emission, and a light emitting element which illuminates the central portion emit light first, The light-emitting elements are made to emit light sequentially from the side closer to the element, distance measurement is performed for each light emission of these light-emitting elements, it is judged whether or not the distance measurement result is a finite distance, and the distance measurement value of the finite distance obtained first is used. And a control means for setting a distance to the subject based on the distance measurement apparatus.