JPH04353713A - Distance measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain a distance measuring apparatus wherein the inner-missing preventing effect is high, distance measuring accuracy is also high and time lag is less furthermore. CONSTITUTION:A distance measuring apparatus has a distance measuring body comprising a turning frame 5 and an IRED 3 and a PSD 4 which are held with the turning frame 5 as a unitary body, a distance measuring circuit 9, an integrating circuit 10, a level judging circuit 11 and a CPU 7. The output of the distance measurement of the PSD 4 in response to the scanning of the IRED 3 is operated in the distance measuring circuit 9. The data corresponding to the distance are obtained by the integrating processing with the integrating circuit 10. The distance operating action for an object is controlled based on the output.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring device, and more particularly, to a distance measuring device for measuring a distance to a wide field of view of a subject in an ordinary camera, video camera, or the like.

0002

[Prior Art] In recent years, as cameras have become increasingly automated, focusing technology has also been developed to overcome the difficulty of distance measurement (distance measurement) for subjects, but this is still not satisfactory. , it is necessary to respond to the following cases. That is, (1) projecting distance measuring light onto the subject;
Measuring the distance of a long-distance subject using so-called active autofocus (hereinafter referred to as AF), which measures the distance using the received signal of the reflected light. (2) Measuring the distance of a subject that exists outside the center of the shooting screen. In other words, it is necessary to measure the distance to prevent missing images. to solve this problem,
As shown in FIG. 9, there is a method in which a light emitting element 51 and a position detecting element 53 are moved and a subject 50 in the screen is scanned with distance measuring light through light emitting and receiving lenses 52 and 54.

0003

[Problems to be Solved by the Invention] In the above-mentioned scanning method, during the scanning operation in order to improve the distance measurement accuracy,
If the distance measurement operation is always performed multiple times, the time lag during scanning cannot be ignored, and there is a possibility that a photo opportunity will be missed. Here, A of a general camera
Thinking about F (autofocus), the control of the camera's focusing lens ignores distant objects among the many distance measurement points, and focuses on the closest distance measurement result as the main subject. There are many cases where this is done. In other words, there is no point in measuring an object at an unnecessarily long distance multiple times in order to obtain highly accurate results.

[0004] The present invention has been made based on the above-mentioned viewpoints in order to solve the above-mentioned problems, and enables highly accurate distance measurement while minimizing the time lag during scanning. The purpose is to obtain a distance measuring device.

[0005]

[Means for Solving the Problems] The distance measuring device of the present invention includes a light projecting means for projecting distance measuring light toward a subject, and a light projector that receives reflected light from the subject and responds to the light receiving position. a distance measuring element having a distance measuring element that emits an output; a scanning means for scanning at least the light projection direction of the light projecting means within the screen in the range finding body; a calculation means for calculating the element output and outputting distance-corresponding data;
a determining means for determining the output level of the distance corresponding data; an integrating circuit for integrating the distance corresponding data; controlling the operation of the integrating means in accordance with the output of the determining means; and arithmetic control means for outputting subject distance data.

[0006]

[Operation] The output of the distance measuring element is calculated in accordance with the scanning of the light projecting means, and the object distance calculation operation is controlled based on the level of the distance corresponding data as a result of the calculation.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be explained below with reference to illustrated embodiments. 1 and 2 are external views of a camera with a built-in distance measuring device showing an embodiment of the present invention, in which a finder 13 and
When viewed from the subject side, a rotating frame 5 that can be rotated for scanning in the horizontal direction (θ) is provided on the left side, which has light emitting and receiving lenses 1, 2, etc., which are the distance measuring bodies of the distance measuring device. has been done. Therefore, as shown in the photographing screen 18 of FIG. 3, it is possible to continuously measure distances at distance points P in the horizontal direction.

Further, FIG. 4 is a block diagram showing an outline of the distance measuring device. As shown in this figure, the distance measuring device is mainly a distance measuring body consisting of the rotating frame 5, and a light projecting means and a position detecting means that are integrally held in the rotating frame 5. a moving part, an actuator 8 which is a scanning means for the rotating frame 5, an IRED driver 6 for lighting the light projecting means, and a measuring means which is a calculation means which outputs distance corresponding data based on the output of the position detecting means. A distance circuit 9, the distance corresponding data,
and an integration circuit 10 that integrates and averages distance data, and a level determination circuit 11 that determines the level of distance-corresponding data at each distance measurement point. It is composed of a CPU 7 that outputs.

The rotating section includes a rotating frame 5 that is rotatably supported by the camera body 14 in the horizontal direction (in the θ direction in FIG. An optical lens 1, an infrared light emitting element (hereinafter referred to as IRED) 3, a light receiving lens 2 of a position detecting means attached to the light projecting means, and an optical position detecting element of a distance measuring element that emits an output according to the light receiving position. (hereinafter referred to as PSD) 4.

An overview of the distance measuring operation in the distance measuring device configured as described above will be explained first.
The rotation frame 5 is rotated to a rotation angle θ1 of a predetermined initial scanning position according to instructions from the CPU 7 (see FIG. 2). A distance measuring light is projected onto the subject 19. The distance measuring light reflected by the subject 19 is guided onto the PSD 4 via the light receiving lens 2. Distance measurement is performed based on the signal of PSD4. As is known, the magnitudes of the two signals I1 and I2 output from the PSD 4 in FIG. 4 depend on the subject distance, and the distance measuring circuit 9 calculates ratio values A and B as shown in the following equation. That is, A=(I1-I2)/(I1+I2)………………(1
) or B= I1/(I1+I2) …………
...(2) Alternatively, the object distance can be determined by determining the sum value, ie, a value such as I1+I2. The output of the ranging circuit 9 is integrated and averaged by an integrating circuit 10.

Furthermore, the rotation angles θ2 and θ of the next scanning position are
Rotate the rotating frame 5 to a ranging point such as No. 3 (see FIG. 2). If the output signal of the ranging circuit 9 at that ranging point is farther than a first predetermined distance, for example, 8 m, it is determined by the level determining circuit 11 based on distance correspondence data corresponding to that distance. , the CPU 7 ignores the distance measurement result and starts the distance measurement operation for the next distance measurement point.
Controlled by Further, if the output of the distance measuring circuit 9 is closer than the first predetermined distance and farther than a second predetermined distance, for example, 2 m, the level determination circuit 11 similarly This is determined by the driver 6, and the IRED 3 is caused to emit light as many times as necessary to obtain the required accuracy. Needless to say, during this time, the actuator 8 is stopped to prevent the rotating frame 5 from moving. Furthermore, since there is sufficient reflected signal light for objects closer than the second predetermined distance, the number of times the light is emitted is limited to increase the distance measurement speed, assuming that the necessary accuracy can be obtained sufficiently. .

Next, the distance measuring operation of the distance measuring apparatus of this embodiment will be explained in detail with reference to the block diagram of the electric circuit shown in FIG. 5 and the time chart shown in FIG. 7. The distance measuring circuit 9 shown in the block diagram of FIG. , two integration circuits 24 and 25, and the level determination circuit 11 further includes a window comparator 26 and a Vref update circuit 27.
shall consist of. It should be noted that the rangefinder is an IRE
The movable part containing D3 and PSD4 is the same as that shown in FIG. 4.

Signal photocurrent component I1,I of the output of PSD4
2 is amplified by absorbing both outputs with low input impedance by preamplifiers 20 and 21. A ratio calculation circuit 22 calculates the ratio of both outputs. Based on the ratio of the outputs, the object distance can be determined using the following equation. That is, 1/
L={t/(s・f)}・{I1/(I1+I2)−a
/t}...(3) Here, the above constants a, t, f, s are
As shown in the optical path diagram of the range finder in Fig. 6, a is PS
It is the length from the end of D4 to the optical axis position of the light receiving lens 2, t is the total length of the PSD 4, f is the focal length of the light receiving lens 2, and s is the length between the light emitting and receiving lenses 1 and 2. This is the baseline length.

Further, the above-mentioned outputs I1 and I2 are calculated in the sum calculation circuit 23 in the form of a sum of I1 +I2. In the distance measuring device of this embodiment, the sum calculation circuit 23 is particularly provided because the result of this sum calculation more accurately represents the S/N of the amount of incident signal light input to the PSD 4. The output result of this sum calculation circuit 23 is integrated by a second integration circuit 25, and the result is used as distance correspondence data. Furthermore, the level is determined by the window comparator 26 based on this output. The reference voltage Vref that serves as the basis for this determination is Vre
f Updated by the update circuit 27 based on the output of the second integration circuit 25. Then, according to the output result of the window comparator 26, the CPU 7 calculates the number of times the IRED 3 emits light and the ratio calculation circuit 2.
The number of times of integration of the first integration circuit 24 that integrates the output signal of the first integration circuit 24 is controlled. Then, when integration is performed a predetermined number of times, the CPU 7 calculates and stores the distance measurement result at the distance measurement point according to the output result of the first integration circuit 24 and the number of integrations.

FIG. 7 is a time chart showing the operation of the distance measuring device. In this figure, θ indicates the rotation angle of the rotation frame 5, and each time this rotation angle θ changes, the IRED 3 The direction in which the distance measurement light is projected changes, and the distance measurement point on the screen changes. First, at the first distance measurement point rotation angle θ1, before the distance measurement operation, the determination range V of the window comparator 26 for determining the distance corresponding data is set.
The lower limit level VcompL of comp is not set. First, read the reference distance.

That is, one distance measurement result obtained by integrating the PSD 4 output by setting the IRED 3 at the rotation angle θ1 is read, and this is set as the lower limit judgment level VcompL (output level a in FIG. 7) of the window comparator 26. . In other words, only objects exceeding this level are subject to multiple distance measurements and data input. Next, in order to read the distance measurement data with sufficient accuracy, the IR
The CPU 7 takes in the output signal of the ratio integral circuit for performing ED light emission, integration, and obtaining actual distance data as data. Furthermore, the result of the summation and integration of light emitted by the IRED 3 n0 times is taken in as the upper limit judgment level VcompH (output level b in FIG. 7) of the window comparator 26. Next, using this data as a reference, if the distance corresponding data obtained by the sum integral during distance measurement at the rotation angle θ2 is longer distance corresponding data than the previous data, that data is ignored and the data is closer than this data. When distance data is obtained, the previous data is canceled and the newly obtained data is used as the basic data.

Therefore, as in the illustrated example, the rotation angle θ2
, θ3, if the sum integral results are smaller than the level VcompL set at the rotation angle θ1, the light projection is finished only once, the distance measurement result is ignored, and the light is moved to the next rotation angle θ4. Then distance measurement is performed there. Here, at the rotation angle θ4, as shown in FIG.
If the sum-integration result becomes a larger value than mpL, the level VcompL is reset to this larger value (output level c in FIG. 7). Then, until the upper limit level summation result of the range Vcomp reaches the output value d in FIG.
The integration of the output of step 4 is repeated, and the ratio integration results are read. Then, by canceling the previously obtained distance measurement value data, the CPU 7 only needs to always store only the most effective data. By repeating this operation, the VcompL level is reset one after another, so conventionally, IR is set only once for all distances beyond the closest distance measured multiple times during scanning.
Since the ED emits light and ignores data, high-speed scanning becomes possible.

The operation of the distance measuring device of this embodiment configured as described above will be explained with reference to the flowchart shown in FIG. When distance measurement is started by pressing the release button, etc., in step S1 the rotation angle of the rotating frame 5 in FIG. 1 is changed to the initial state θ.
= θ1. In step S2, the lower limit determination level VcompL of the window comparator 26 is initialized to zero. In step S3, the circuit shown in FIG. 5 performs the first distance measuring operation based on the emission of the distance measuring light IRED 3 and the sum integral and ratio integral.

Among the calculation results, the sum-integration result is stored as the level VcompL. This level Vco
mpL is the rotation angle θ of the ranging point θ2, θ3...
Each time the distance is rotated, it is compared with the sum integral result of the previous distance measurement, and if the sum integral result at that time is larger than the level VcompL, that is, if the current distance measurement indicates a shorter distance than the previous distance measurement, the level VcompL is updated to the larger sum-integration result at that time. This kind of operating function is shown in Figure 5.
This is performed by the Vref update circuit 27. Due to this function, the output value of the sum integral at that time is at the level VcompL
If the current distance measurement value is less than the previous distance measurement value, that is, for a subject whose distance is farther than the previous distance measurement value, the distance measurement integration is not performed many more times. In other words, when the determination in step S4 is "N", steps S14 and S1
5, in order to measure the next distance measurement point, the rotation frame 5 is driven to a position where the unit drive angle Δθ is added to the current rotation angle θ, and the process returns to step S3.

On the other hand, the output value of the sum integral is at the level Vcomp
If the level exceeds L, that is, if the determination in step S4 is "Y", the process proceeds to step S5, and the level V
The output value of the sum integral is stored as compL. Subsequently, distance measurement integration is performed multiple times at that distance measurement point. This process is shown in steps S6 to S13. In step S6, the number of distance measurements n is set to 1. In step S7, similarly to step S3, light emission from the IRED, summation integration, and ratio integration are performed. As explained earlier,
When the rotation angle θ is the initial rotation angle θ1, distance measurement is repeated until the number of integrations n reaches a predetermined number n0. The number of times is checked in step S11. The final summation result is set to the upper limit judgment level Vcomp in step S12.
Store it as H. This storage is also performed by the Vref update circuit 27 in FIG.

When the rotation angle θ is other than the initial angle θ1,
The distance measurement operation in step S7 is repeated until the sum integration result reaches this level VcompH (step S10).
, and when that level is exceeded, the sum integration result is stored as an updated level VcompH (step S12).
. Every time the level VcompH is updated, the ratio integration result is stored as a value Dt and the number of distance measurements n is stored as a value nt and updated in step S16, which will be described later. (Step S1
3). Then, the process advances to step S14. Step S14
, 15 is the process of setting the rotating frame 5 at the next ranging point as described above, but if the rotating frame scans the entire ranging range and the rotating angle reaches θmax, step S16 Jump to.

Now, to explain the distance calculation in step S16, the ratio integral result value Dt is determined by the calculation of equation (2) n
Since it has been performed t times, the value is
Dt={I1/(I1+I2)}・nt...
...... is output as (4). Therefore, when distance information 1/L is calculated based on equation (3), 1/L=(t/s
・f)・(Dt/nt-a/t). This operation is
The CPU 7 in FIG. 5 performs this.

[0023] The above levels VcompL, VcompH
The distance measurement of unnecessary points is canceled by updating the value of , and the distance measurement of important points is repeated until sufficient distance measurement accuracy is obtained, and high-precision distance measurement can be performed by integrating and averaging calculations. become. As explained above, the distance measuring device of this embodiment is configured such that the level determination circuit 11 and the CPU 7 control the number of times the IRED 3 emits light so as to reduce the distance measuring time per distance measuring point as much as possible. There is. Therefore, a highly accurate and high speed scanning distance measuring device can be provided. In this embodiment, the sum integral value of the second integrating circuit 25 is used as the distance corresponding data, but of course,
The output value of the first integrating circuit 24, which integrates the output of the ratio calculation circuit 22, may be used as the data.

[0024]

[Effects of the Invention] As explained above, the distance measuring device of the present invention calculates the output of the distance measuring element according to the scanning of the light projecting means, and
Since the object distance calculation operation is controlled based on the level of the distance corresponding data obtained from the calculation result, the object distance calculation operation of the present invention has remarkable effects such as preventing hollow spots, high distance measurement accuracy, and little time lag. It has many effects.

[Brief explanation of the drawing]

FIG. 1 is a front view of a camera incorporating a distance measuring device showing an embodiment of the present invention.

FIG. 2 is a plan view of the camera shown in FIG. 1;

FIG. 3 is a diagram showing each distance measurement point on the screen of the distance measurement device shown in FIG. 1;

FIG. 4 is a schematic block diagram of the distance measuring device shown in FIG. 1;

FIG. 5 is a block configuration diagram of an electric circuit of the distance measuring device shown in FIG. 1;

FIG. 6 is an optical path diagram of the range finder of the range finder shown in FIG. 1;

[FIG. 7] Time chart of distance measurement operation of the distance measurement device shown in FIG. 1 above.
to.

FIG. 8 is a flowchart of distance measurement processing performed by the distance measurement device shown in FIG. 1;

FIG. 9 is an optical path diagram of a range finder of a conventional range finder.

[Explanation of symbols]

1......Light projection lens (light projection means, range finder) 2...
...... Light receiving lens (distance measuring object) 3 ...... IRED (light emitting means, ranging object) 4 ......
......PSD (distance measuring element, distance measuring body) 5......Rotating frame (scanning means) 7......CPU (computation control means) 8......
Actuator (scanning means) 9...... Distance measuring circuit (
Calculation means for outputting distance corresponding data) 10......Integrator circuit 11...Level judgment means (judgment means) 22...
…………Ratio calculation circuit (calculation means that outputs distance-corresponding data) 23……………… Sum calculation circuit (calculation means that outputs distance-corresponding data)

Claims (1)

[Claims] Claim 1: A light projection device that projects distance measuring light toward a subject; and a distance measuring element that receives reflected light from the subject and outputs an output according to the light receiving position. a distance measuring body, a scanning means for scanning within a screen the light projection direction of at least the light projecting means in the distance measuring body, and calculating a distance measuring element output according to the scanning of the light projecting means and outputting distance-corresponding data. a calculating means for determining the output level of the distance-corresponding data; a determining means for determining the output level of the distance-corresponding data; an integrating circuit for integrating the distance-corresponding data; A distance measuring device comprising: arithmetic control means for outputting object distance data according to an output of the means.