JPH03210546A - Range finding device for camera - Google Patents

Abstract

PURPOSE:To simplify the focusing of a camera by adopting the range finding data of a center range finding point when a releasing time interval between the 1st and 2nd steps exceeds a prescribed value, and adopting the range finding data of an optional range finding point out of plural points when the time interval is less than the prescribed value. CONSTITUTION:The range finding device is provided with plural range finding means 1, 2 for measuring the distances of plural points in a photographing field and outputting plural distance information in the 1st step operation (7) out of releasing operation, a lens driving means 5 for driving a photographing lens 6 to a focusing position corresponding to optional information out of plural distance information in the 2nd step operation (8), a timer means 3 for starting clocking by the 1st step operation, and a deciding means 3 for outputting a signal when the 2nd step operation is not executed if the count time of the means 3 does not reach a prescribed time. In this constitution, the lens 6 is driven to the focusing position corresponding to the distance information of the center of the photographing field out of the distance information of plural points. Thus, focusing can simply and quickly attain without executing complex operation.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a distance measuring device for a camera, and more particularly, to a distance measuring device for a camera having a multi-point distance measuring function for measuring object distances at multiple points within a photographic image frame. It is related to the device.

[Prior Art] As is well known, a distance measuring device in an autofocus (hereinafter referred to as AF) camera generally measures the distance to a subject (object) located in the center of the photographic image frame, and calculates the distance to the subject. Focusing is performed by moving the photographic lens according to the distance.

However, with the conventional distance measuring device for the AF left camera configured in this way, if the subject is not located in the center of the shooting image frame, a loss of focus called "middle drop" occurs and the focus is fixed at infinity. However, the disadvantage of this method is that it results in a photograph that is too sharp, and that it is not possible to accurately focus on the desired subject.

Therefore, in order to eliminate such defects, as shown in FIG. 7, a plurality of points, such as the center (hereinafter referred to as point C), within the photographic image frame 10 are set.

By measuring the three points on the left side (hereinafter referred to as point L) and on the right side (hereinafter referred to as point R), the shooting image frame 1 is
Even when the subject is not located at the center of The camera is configured to select the closest distance measurement result from among a plurality of distance measurement points based on the probability of existence of the subject and perform focusing.

However, even in the AF left camera having this multi-point distance measuring device, there still exist the following problems. For example, the seventh
When the subject 11 you want to focus on is in the center as shown in the photographic screen shown in the figure, the point you want to focus on is the center of point "C," but the left and right distance measurement points "L."

Since the rRJ focuses on the window frames 12a and 12b, which are at a closer distance, this side, that is, on this screen, the window frames 12a and 12b are in focus.

Therefore, in order to solve this problem, it is conceivable to provide a spot ranging mode in which focusing is performed based only on the center ranging data.

Also, if you want to place the subject you want to focus on somewhere other than the distance measuring points rcJ, rLJ, or rRJ, place the subject you want to focus on in the center, press the release button halfway, and then press the first release button. Measure distance by operation,
After that, a so-called focus lock is effective, which involves composing the camera to the desired composition, pressing the release button all the way, and releasing the shutter with the second release operation.In this case, it is also advantageous to have a spot distance measurement mode. .

[Problem to be solved by the invention] However, in the AF left camera having a multi-point distance measuring device,
In order to solve the above problem, when the spot distance measurement function is equipped, the photographer has to use multi-point distance measurement mode or spot measurement mode, even though the AF left camera is convenient for shooting. There is the hassle of having to select distance mode and then switch to that mode.

Therefore, an object of the present invention is to provide an AF left camera equipped with a multi-point ranging mode and a spot ranging mode, so that the optimum ranging mode can be selected for shooting without the need for troublesome switching operations to each mode. To provide a distance measuring device for a camera that can quickly focus on a desired subject by selecting the subject.

Means for Solving Problem C] The distance measuring device for a camera according to the present invention measures distances at a plurality of points within the photographic field of view by the first stage operation of the release operation, and measures distances to objects located at the plurality of points. A distance measuring means that outputs the distance as a plurality of distance information, and a lens that drives the photographing lens to a focusing position corresponding to arbitrary information among the plurality of distance information by a second stage operation of the release operation. a driving means; a timekeeping means for starting time counting by the first stage of the release operation; and a timekeeping means that outputs a signal if the second stage operation is not performed when the time counted by the timekeeping means reaches a predetermined time. and a determination means for outputting, based on the signal from the determination means, the photographing lens is brought into focus corresponding to the distance information at the center of the photographic field of view among the distance information of a plurality of points within the photographic field of view. It is characterized by being driven into position.

Further, another camera distance measuring device according to the present invention includes a distance measuring means that measures a plurality of points within a photographic field of view and outputs a plurality of distance information, and a distance measuring device that measures a plurality of points within a photographic field of view and outputs a plurality of distance information, and a distance measurement device that measures a plurality of distances during the first stage of the release operation. If there is a difference between the determination result by the determination means and the determination means that compares the information with a plurality of distance information during the second stage of the release operation, the distance information corresponds to the center of the photographing field during the first stage of the release operation. It is characterized by comprising a lens driving means for focusing the photographic lens at a distance position.

[Function] In the distance measuring device of the camera described above, when the time interval between the first release and the second release is equal to or greater than a predetermined value, the distance measurement data from the center distance measurement point to the point is adopted. However, when the time interval is less than a predetermined value, a focusing operation is performed using a distance obtained by a predetermined method from distance measurement data of a plurality of distance measurement points.

In addition, in the above-mentioned distance measuring device of another camera, the distance measuring data at the timing of the first stage release operation and the second
Automatically determines that the photographer has changed the composition based on changes in the distance measurement data at some of the multiple distance measurement points by comparing the distance measurement data at the timing of the shutter release operation. Then, focusing is performed according to the distance measurement data at the center of the screen at the time of the first release operation, which is considered to be the first subject that the camera was aimed at.

[Example] The present invention will be explained below with reference to an illustrated embodiment.

FIG. 1 is a block diagram showing the basic configuration of a distance measuring device in an AF right camera according to the present invention. The screen center distance measuring means 1 is a first distance measuring means for measuring the distance to a subject located at the center of the photographic image frame of the finder, and is a first distance measuring means that measures the distance to a subject located at the center of the photographing image frame of the finder. It corresponds to distance point "C". Further, the screen peripheral distance measuring means 2 is a second distance measuring means for measuring the distance to a subject located at the periphery of the photographing image frame of the finder, and is a second distance measuring means for measuring the distance to a subject located in the peripheral part of the photographing image frame of the finder. Ranging points “L” and r
Compatible with RJ.

The signals measured by these distance measuring means 1.2 are
Each is input to the calculation means 3. This calculation means 3 is
It is designed to control all sequence operations of this AF camera, and is composed of a CPU consisting of a one-chip microcomputer, for example, and is turned on in conjunction with the half-press of the shirt release button. recognizes the input signal from the distance measuring means 1 and 2, performs time-division control of the distance measuring means 1 and 2, and inputs the signals of the respective distance measurement results, further counts the time since the second release operation, and determines that the count value is a predetermined value. When the value reaches or exceeds the value, the display means 4 is driven. Further, when the input signal from the second release operation switch 8, which is turned on in conjunction with the complete pressing of the shirt release button, is recognized,
The distance adjusting means 5, which is a lens driving means, is controlled according to the determination result of the distance measurement information.

The distance adjusting means 5 is composed of a motor, a driver, an encoder, etc. that controls the driving of the photographing lens 6.

The display means 4 is composed of a light emitting element such as an LED (light emitting diode), and emits light in the viewfinder when the time from the second release operation exceeds a predetermined value and the distance selection means changes. , which serves to inform the photographer of this.

Further, if the count second time t reaches a predetermined second time t6 or more before the second release operation switch 8 is turned on, the calculation means 3 drives the display means 4 at that point to display the spot distance measurement. After that, the camera returns to the state of waiting for the 'M2 release operation. Thereafter, when the second release operation switch 8 is turned on, the distance measurement result pc of the distance measurement point "C" at the center of the shooting screen is selected as the subject distance, and the distance adjustment means 5 is controlled so as to focus there. The photographic lens 6 is advanced, and after the lens 6 is advanced, a normal exposure sequence is executed. As a result, a photograph is taken in which the subject at distance measurement point "C" in the center of the finder is the main subject.

Next, the distance measuring means 1.degree.2 for performing AF distance measurement shown in FIG. 1 will be explained in detail.

In the camera of this embodiment, as the distance measuring means 1.degree. 2, an infrared light active type triangular distance measuring method having the configuration shown in FIG. 2 is basically adopted.

In Figure 2, an infrared light emitting diode (hereinafter referred to as IRED)
The infrared light emitted at 13 (abbreviated as ) is transmitted to the projection lens 14
The light is focused and irradiated toward the subject 2o. This reflected light from the subject 20 is imaged by a light receiving lens 15 onto a well-known position detection element (hereinafter abbreviated as PSD) 16 made of a semiconductor element. In this PSD 16, the photocurrents I and I2 are divided according to the imaging position, and the divided photocurrents I and I2 are supplied to an AF IC (integrated circuit) 17. This AF IC17 is IRED
The IRED 13 is pulse-driven through the control transistor 18, and the photocurrent from the PSD 16 is also applied. ,
, I2 is supplied to the calculation means 3.

Here, the optical axis of the light-receiving lens 15 is made to match the central axis of the PSD 16, and when this is set as the origin, the incident position of the reflected light is x1, the distance between the principal points of the light-emitting lens 14 and the light-receiving lens 15,
In other words, if the baseline length is 51 and the focal length of the light receiving lens 15 is fa, then the subject distance d is given by d=s-f a/x -= (1).

P due to the reflected light from the object 2o by IRED13
Photocurrent generated in SD16 11. Both I2 are proportional to the reflected light intensity, but the photocurrent ratio 11/I2 does not depend on the reflected light intensity and is determined only by the incident light position X. Therefore, if the total length of PSD 16 is t, the photocurrent ratio is 11/I2
The ratio 11/■2 is 5fa 11/l2=(t+-)/(t2sfa,...
(2) Since d d , if the photocurrent ratio 11/12 of the PSD 16 is found, the subject distance d can be uniquely determined.

In addition, in Figure 2 above, in order to simplify the explanation of the distance measurement principle of the active triangulation method, a configuration is shown in which simple one-point distance measurement is performed, but the distance measurement when this is changed to three-point distance measurement is The configuration of the optical systems of means 1 and 2 is shown in FIG.

In this FIG. 3, there are three IREDs 13a.

13b, 13c, 3 PSD16a.

16b and 16c are used. And 3 IR
Each distance measuring infrared light beam 18a from ED13a to 13c
, 18b, 18c are directed toward the subject 20 by the light projection lens 14, and each beam returned from the subject 20 is made incident on the corresponding one of the three PSDs 16a to 16c by the light receiving lens 15. In addition, in this FIG. 3, the light projecting lens 14 and the light receiving lens 15 are arranged in the horizontal direction so that the overall structure can be easily understood.

However, in reality, it is necessary to change the horizontal arrangement shown in FIG. 3 to a vertical arrangement. That is, the light emitting lens 14 and the light receiving lens 15 are arranged vertically, and the three IREDs 13a to
The infrared light beam from 13c is transmitted to each distance measurement point rLJ, rCJ, rRJ in the field of view in the finder shown in FIG.
It is necessary to correspond to each.

As a specific example of the configuration of the optical system in these distance measuring means 1.2, the infrared light beam 1 from the central IRED 13b is
Left and right IRED13a for 8b.

The angle α formed by the infrared light beams 18a and 18c from the IRED 13c is determined to be approximately 7°.

If the distance between 13b and 13c is gl, and the focal length of the projection lens 14 is fal, then tan a-g, /f a.

designed to satisfy.

Also, the distance between the above PSDs 16a, 16b, and 16c is set to g2.
, if the focal length of the light-receiving lens 15 is fa2, then the mutual focal length of the lenses 14 and 15 is f a l -
When set to f a 2, I RED13a, 13b, 1
3c spacing and PSD16a.

The spacing between 16b and 16c is set to gl""g2, respectively.

Note that the reason why the PSD is divided into three is to minimize the influence of incident light from other directions during negative point distance measurement, thereby improving the S/N ratio.

FIG. 4 shows A of this embodiment configured as shown in FIG. 1 above.
It is a flowchart showing an example of the distance measurement information determination operation of the calculation means 3 in the F left camera distance measurement device.

As shown in this flowchart, when the photographer now presses the shirt release button halfway to turn on the first release operation switch 7, the first release operation is started. That is, in this Lullies, first a counter that counts seconds starts. Next, the distance to the subject at the distance measuring point rCJ at the center of the screen of the finder is measured by the screen center distance measuring means 1,
Following this, the distance measurement point r on the periphery of the viewfinder screen
Measurement of object distances at LJ and rRJ is performed by the screen periphery distance measuring means 2.

The distance measurement result I by both distance measuring means 1 and 2. .

p,,IR are sent to the calculation means 3 as described above, and the calculation means receives the distance measurement result I at 22. , 1. , IR, the closest distance IN is calculated.

Thereafter, the camera enters a state of waiting for the second stage release operation while determining the time. When the second release operation switch 8 is turned on when the count second time t is equal to or less than a predetermined second time t, the distance adjustment means 5 is controlled so that the subject at the closest distance IN is in focus, and the photograph is taken. After the lens 6 is extended, a normal exposure scene is executed. As a result, a photograph is taken in which the main subject is the one closest to the subject at each of the distance measurement points rLJ, rRJ, and rCJ of the finder.

Also, to explain the operation when the focus is locked,
Generally, when locking the focus, as shown by the dotted line in Figure 6, first place the subject 11A you want to focus on at distance measuring point "C" in the center of the shooting image frame 10A, and press the shirt release button halfway. The distance is measured using the distance measurement point “C”. After that, as shown by the solid line in FIG.
0, I set the desired composition, press the shirt release button fully, and release the shutter. Therefore, in this example, in the flow shown in FIG. 4, the predetermined time tb is set to be shorter than the time required for focus locking and longer than when focus locking is not performed. By doing this, when the focus is locked,
Spot distance measurement can always be used. in this case,
Even if there is something in front of the subject you want to focus on,
There is no need to change from the multi-point distance measurement mode to the spot distance measurement mode, and there is no need to worry about which subject is being measured by the screen peripheral distance measurement means 2.

In addition, in this example, the method of selecting the subject as a result of multi-point distance measurement is to select the closest object, but the present invention calculates the focusing distance by considering the depth of field. Needless to say, it is okay to do so.

Next, the flowchart of FIG. 5 shows another example of the operation for determining distance measurement information by the calculation means 3 in the AF left camera distance measurement device of this embodiment.

The means of this other example can also be achieved by the distance measuring device having the configuration shown in FIG. However, in the means of this other example, in the distance measuring device shown in FIG. It is also necessary to have a function of receiving data and determining the amount of extension of the photographing lens 6 by comparing the data.

In the flow shown in FIG. 5, the first stage release operation is started at the closing timing of the Lullies operation switch. Then, the distance 'C1 of the subject located at the center of the screen is determined by the distance measuring point "C", and the distance p and 'R1 of the subject located at the periphery of the screen is determined by the distance measuring means 1 at the center of the screen, and the distances p and 'R1 of the subject located at the periphery of the screen are determined by the ranging points rLJ and rRJ. It is determined by distance measuring device 1 and stage 2 around the screen.

Next, when the second release is performed, the distance I of the subject located at the center of the screen is again adjusted. 2 and the distance NfIL2''R2 of the subject existing at the periphery of the screen.

And, these distance measurement points rcJ, rLJ.

In "R", if the distance measurement data are equal, that is, the distance measurement data of distances M1o1 and 1°2 are equal, and the distance measurement data of distances 'LL and 'L2 and the distance MIR work and "R2
When the distance measurement data are equal, there is no movement of the subject and there is a low probability that the photographer changed the composition, so a closest-to-focus calculation gN is performed to focus on the closest subject among the respective distance measurement data. .

In addition, if the distance measurement data for distances 1゜1 and 1゜2 are equal, and the distance measurement data for distances "Ll" and "L2" are equal, and only the distance measurement data for distances 11R and "R2 are different, or distances 1C1 and g.2 distance measurement data and distance J7
If the distance measurement data of R1 and "R2" are the same, and the distance measurement data of only "Ll" and "Ω" and "2" are different, it is assumed that only the subject existing in the surrounding area has moved.
In this case as well, the probability that the photographer changed the composition is low, so in this case as well, among the distance measurement data at the time of the second shutter release,
It focuses on the closest subject and performs multi-point AF operation that prevents "focusing".

However, distance g and 2 1 distance 'Ll and 'L2 and CI
When all the distance measurement data for C2, distance MJR1, and 'R2 are different between the first-stage release timing and the second-stage release timing, there is a high probability that the photographer has changed the composition. Therefore, at this time, in the same way as the operation in the flowchart shown in FIG. 4, the focus is adjusted to the distance of the subject that was present at the center of the screen at the time of the first release, and the exposure sequence is started.

In this way, it is possible to provide a multi-point distance measuring device that is easier to use.

[Effects of the Invention] As described above, according to the present invention, in the AF left camera distance measuring device having a multi-point distance measuring function, when it is desired to reliably focus on one point in the center, no preliminary operation is required. Since there is no need to do this, a remarkable effect can be obtained in that it becomes extremely easy to use focus lock and the like.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the configuration of a camera distance measuring device showing an embodiment of the present invention. FIG. 2 is a schematic diagram showing the basic configuration of an infrared active triangular distance measuring method. 4 is a schematic diagram showing the configuration of the three-point distance measuring device using the infrared light active triangulation method, and FIG.
5 is a flowchart showing an example of the operation of determining distance information by the calculation means in the distance measurement device shown in FIG. 5; FIG. Flowchart. FIG. 6 is a diagram showing an example of the movement of the photographic image frame when focus is locked. FIG. 7 is a diagram showing an example of the photographic image frame in a conventional three-point distance measuring device. 1... Screen center distance measuring means (distance measuring means) 2
......Screen peripheral distance measuring means (distance measuring means) 3.
......Calculating means CPU (timekeeping means 9 judgment means)5... Distance adjustment means (lens driving means)6... Photography lens

Claims (2)

[Claims] (1) A distance measuring means that measures a plurality of points within the photographic field of view by the first stage operation of the release operation, and outputs the distance to an object at the plurality of points as a plurality of distance information; a lens driving means for driving the photographing lens to a focusing position corresponding to arbitrary information among the plurality of distance information by a second stage operation of the above; and a time measurement is started by a first stage operation of the release operation. a timer for measuring time, and when the time measured by the timer reaches a predetermined time,
and a determining means for outputting a signal when the second stage operation is not performed, and the photographing lens is configured to detect distance information of a plurality of points within the photographic field of view based on the signal from the determining means. A distance measuring device for a camera, characterized in that it is driven to a focusing position corresponding to distance information at the center of a photographic field of view. (2) A distance measuring means that measures multiple points within the photographic field of view and outputs multiple pieces of distance information, and multiple pieces of distance information during the first stage of the release operation and during the second stage of the release operation. a determination means for comparing a plurality of pieces of distance information in the determination means; and a lens for focusing the photographing lens at a distance position corresponding to the center of the photographic field during the first stage operation if there is a difference in the determination result by the determination means. A distance measuring device for a camera, comprising: a driving means;