JPH06100463B2 - Distance measuring device in camera - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a distance measuring device in an autofocus camera capable of measuring distances at a plurality of points.

(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, when infrared light is collected, the distance measuring range on the screen becomes narrower. For example, when two people are lined up,
When the center of the viewfinder is set between two people, infrared light passes through between the two people and is irradiated, and the background of the person is in focus, resulting in incorrect distance measurement. In order to solve such a problem, various means for expanding the range-finding range on the screen are known.

For example, as described in U.S. Pat. No. 4,470,681, the image forming lenses for the infrared light emitting diode and the light receiving element are connected to each other to be horizontally movable. In other words, a method is known in which two lenses for projecting light and receiving light are moved at the same time in the state where the same point is imaged, and the object surface is scanned by infrared light. In addition to this, a technique is also described in which each imaging lens for an infrared light emitting diode and a light receiving element is formed into a lens array that is a compound eye, and distance measurement is performed at points corresponding to the number of 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. It is also known to generate a first-order diffracted beam on both sides and scan the object surface with these three beams.

As described above, both the one in which both imaging lenses are horizontally moved and the one in which the light emitting source is rotated enable the multi-point distance measurement by scanning the object surface.

However, in this way, both imaging lenses can be moved horizontally,
Providing a movable portion that rotates the light emitting source has a problem in durability and may reduce accuracy.

Further, in the method using the lens array, the optical axes of the lens arrays of the light emitting section and the light receiving section must be aligned, which is complicated, and when the lens array is used, the distance measuring section becomes large, which is large in terms of camera design. You will be constrained.

On the other hand, as described in Japanese Patent Laid-Open No. 60-60511, there is also described a configuration in which the light emitting means and the light receiving means are vertically positioned with the imaging lens interposed therebetween.

(Problems to be solved by the invention) However, in the configuration described in Japanese Patent Laid-Open No. 60-60511, in general, ambient light such as illumination light and sunlight is radiated downward from above, When ambient light is emitted to the light receiving means for erroneous detection, the focus is on a distance shorter than the actual subject distance, which causes a problem that defocus may occur.

An object of the present invention is to provide a distance measuring device in a camera capable of preventing erroneous distance measurement even if ambient light enters.

[Structure of Invention]

(Means for Solving the Problems) The present invention provides a light emitting source that irradiates a subject with infrared light, and a light emitting source that is arranged to maintain a baseline length to emit reflected light from the subject. The camera body is equipped 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 for a camera, the light emitting source and the one-dimensional semiconductor position detecting element are arranged in a vertical direction on the front surface of the camera body, and the one-dimensional semiconductor position detecting element is located above the light emitting source. Is.

(Function) The present invention irradiates infrared light from a light emitting element of a light emitting source, receives reflected light of infrared light reflected by a subject by a one-dimensional semiconductor position detecting element, and the one-dimensional semiconductor position detecting element Distance to the subject is measured based on the output from. Further, since the light emitting source and the one-dimensional semiconductor position detecting element are arranged in the vertical direction and the one-dimensional semiconductor position detecting element is provided above the light emitting source, even if ambient light enters the one-dimensional semiconductor position detecting element, Since the distance measurement becomes erroneous in the long-distance direction and the depth of the subject becomes deeper than that in the case where erroneous distance measurement is performed in the short-distance direction, it is easy to prevent out-of-focus.

Embodiment An embodiment of the distance measuring device in the camera of 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 emitting source 13 is arranged so as to face the light projecting lens 11 with a distance f1 therebetween, and a plurality of (n) light emitting sources 13 are arranged in parallel 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 has a base line length l in its length direction. Are arranged along the y-axis direction.

Further, 15 is a subject, and each optical axis represents irradiation light to the subject 15 at each position N, M, F and reflected light from the subject 15, and each reflected light is one-dimensionally transmitted through the light receiving lens 12. The light is received at each position on the y-axis of the semiconductor position detecting element 14. In this case, a plurality of infrared light emitting diodes IR1, IR2, ...
,, the light emitted from IRn has the same position, for example, position M
When reflected by the subject 15, the image is formed on the one-dimensional semiconductor position detecting element 14 in a line in the width direction (x axis) at the same position on the y axis.

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. When 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 instruction switch 25 gives the shortest value selection command to the microcomputer 20 in its ON state, and gives the 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. 20 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 in the case of shooting a subject in which two persons located relatively close to each other and a background in the distance are combined 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 this data is output to the 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, without providing the light emission selecting means 24 shown in FIG. 4, a microcomputer is provided with a program for automatically controlling the light emission according to a predetermined order of a plurality of infrared light emitting diodes IR1, IR2 ,. You may set it to 20.

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.

Next, another embodiment will be described with reference to the flowchart shown in FIG.

In the embodiment shown in FIG. 7, it is discriminated whether or not it is infinity, whereas in the embodiment shown in FIG. 8, the measured distance value is stored and the stored value and the adjacent distance measurement value are discriminated. It is a thing. That is, first, distance measurement is performed in the center (step 11), this distance measurement value is stored (step 12A), and then distance measurement is performed next to the center (step 13A). If it is large, that is, if it is far away, the neighboring distance measuring units are determined to be closer, and distance measurement is continued until the stored value becomes smaller (steps 14A to 18) until the stored value becomes smaller. The distance measurement is continued and the lens is driven (step 19). Then, it is determined that the subject exists at least independently near the center of the screen.

In FIG. 8, the light emitting diodes are lit alternately from the center to the left and right, but as another method, for example, the range is first expanded from the center to one left direction and the range measurement value in that direction is temporarily set. After memorizing, the range is expanded to the right of the other side, the range measurement value in that direction is temporarily stored, and finally the stored range values are compared to finalize the value. You can do it.

〔The invention's effect〕

According to the distance measuring device in the camera of the present invention, the light emitting source and the one-dimensional semiconductor position detecting element are arranged in the up-down direction, and the one-dimensional semiconductor position detecting element is provided above the light emitting source. Even if it enters the semiconductor position detecting element, the distance measurement becomes erroneous in the long-distance direction, and the depth of the subject becomes deeper than that in the case of erroneous distance measurement in the short-distance direction, so that defocusing can be prevented.

[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. FIG. 5 is an external view of the same camera as above, FIG. 6 is a view showing the inside of the finder at the time of distance measurement, same as above, FIG. 7 is a flow chart for explaining the operation of the other embodiment of the same as above, and FIG. 3 is a flowchart showing the operation of FIG. 13 ... Emission source, 14 ... One-dimensional semiconductor position detection element, 15 ...
… Subject, 30 …… Camera body, l …… Baseline length.

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

Claims (1)

[Claims] 1. A light emitting source for irradiating a subject with infrared light, and a light emitting source arranged to maintain a baseline length for receiving reflected light from the subject. A one-dimensional semiconductor position detecting element whose electric output changes according to the camera body, and a distance measuring device in a camera for measuring a distance to a subject based on the output of the one-dimensional semiconductor position detecting element, wherein the light emitting source And the one-dimensional semiconductor position detecting element is arranged in a vertical direction on a front surface of the camera body, and the one-dimensional semiconductor position detecting element is located above the light emitting source.