JP2000089098A - Multipoint range-finding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multipoint range finding device improved in shift arithmetic method in order to shorten the time required for a range-finding action as for a passive phase difference type camera system constituted so that the range-finding actions of plural range-finding areas can be executed. SOLUTION: This multipoint range-finding device is constituted so that the time required for range-finding arithmetic operation is shortened by making the shifting frequency of shift arithmetic operation with respect to the range- finding area other than the center of a photographing area smaller than that with respect to the range-finding area set at the center of the photographing area when the shift arithmetic operation is executed by a microcomputer 1. The shift arithmetic operation is executed in order to obtain range-finding data in the plural range-finding areas set within the photographing area of a range-finding sensor 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase difference type camera capable of adjusting the focus of a plurality of distance measuring areas in a photographing area based on the principle of triangulation.

[0002]

2. Description of the Related Art Conventionally, in a distance measuring apparatus used for a TTL camera, for example, a maximum (MAX) value of a defocus amount determined by a photographing lens as described in Japanese Patent Application Laid-Open No. Sho 62-133409 is known. There is known a technology that realizes a reduction in the operation time by performing a necessary shift operation in response.

However, regardless of whether the distance measuring device is of the TTL system or the non-TTL system,
In this method, two subject images formed by a pair of separator lenses are received by an image sensor.

The distance between two images formed on the image sensor is obtained by repeating a shift operation, and a defocus amount or a distance to a subject is calculated.
Since the shift operation increases the load on the CPU, it is necessary to reduce the amount of operation to a small amount in order to shorten the operation time.

[0005]

However, as a method for shortening the calculation, a distance measuring point (ranging area) is simply used.
Is set to only one point at the center of the shooting area, and if there is no main subject at that center position during shooting,
In other words, a so-called hollow hole occurs, and a photograph in which the main subject is in focus cannot be taken.

As a countermeasure, various systems have been proposed in which a plurality of distance measuring areas are set in a photographing area, a distance measuring operation is performed, and a focused photograph can be taken even when a main subject is not always located at the center. Has been realized.

However, the phase difference method originally requires a large amount of calculation,
Even when calculating the distance measurement data for one point of the distance measurement area, the CP
The load on U is not small. Therefore, the release time lag is large as compared with other methods.

If a plurality of distance measurement areas are set and distance measurement data is obtained from them, the time lag is further increased. Accordingly, the present invention provides a multi-point ranging apparatus in which a shift operation method is improved in a passive phase difference type camera system capable of performing a ranging operation on a plurality of ranging areas, in order to shorten a ranging operation time. The purpose is to do.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a plurality of distance measuring areas respectively arranged at a central portion and a peripheral portion of a region to be measured, and a pair of imaging lenses. Is a multi-point distance measuring apparatus that detects the distance between the pair of subject images formed by the above and obtains the distance to the subject in the distance measuring area, and detects the distance between the pair of subject images. To provide a multi-point distance measuring apparatus in which the shift calculation range in the correlation calculation for the central section and the peripheral section differs. Further, the shift calculation range in the correlation calculation is set to be narrower in the peripheral portion than in the central portion.

The above-described multi-point distance measuring apparatus is set at a position other than the center of the photographing area when executing a shift operation to obtain distance measurement data of a plurality of distance measuring areas set within the photographing area. The number of shifts in the shift calculation for the distance measurement area that was set is smaller than the number of shifts in the shift calculation for the distance measurement area set in the center of the shooting area. Time becomes shorter.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a configuration example of an embodiment according to a multipoint distance measuring apparatus according to the present invention, and will be described.
In this embodiment, a microcomputer 1 for controlling the entire distance measuring device, a distance measuring sensor 3 for measuring a distance to a subject 2, an interface circuit 4 for controlling the distance measuring sensor 3, and parameters required for calculating the distance E to memorize
It comprises an EPROM 5, a lens motor 7 and a motor drive circuit 8 for driving the taking lens 6, and a position encoder 9 for detecting the position of the taking lens 6.

The distance measuring sensor 3 comprises a pair of separator lenses 11a and 11b and a line sensor 12 composed of a pair of L sensor 12a and R sensor 12b disposed opposite to the pair. The line sensor 12 is composed of, for example, a photoelectric conversion element such as a CCD.

The images of the subject are formed on the light receiving surfaces serving as the detection surfaces of the L and R sensors 12a and 12b, respectively, by the separator lenses 11a and 11b. These L sensors 1
2a and the R sensor 12b output a detection signal indicating the interval between two images formed on the light receiving surface. Based on the sensor data storing the detection signal, the microcomputer 1
Calculates the distance to the subject 2.

First, the microcomputer 1 instructs the interface circuit 4 to start integration of a detection signal detected by the line sensor 12, and the interface circuit 4
Then, integration of the detection signal is started. Then, when the accumulation level reaches a predetermined value, the interface circuit 4
An integration end signal is output to the microcomputer 1.

Next, in response to an output instruction from the microcomputer 1 to the interface circuit 4, the line sensor 12
The signals (sensor data) stored in a and 12b are output to the microcomputer 1 via the interface circuit 4.

The sensor data input to the microcomputer 1 is converted into digital data by an A / D converter 13 provided therein, and the RAM provided therein is similarly provided.
14 is stored.

The microcomputer 1 includes a distance measuring sensor 3
The object distance is calculated from the data obtained from the above by an arithmetic processing method described later, and the object distance is converted into the movement amount of the photographing lens 6.

Based on the amount of movement, the taking lens 6
Driven by the lens motor 7 controlled by the motor drive circuit 8. The position of the taking lens 6 is determined by a position encoder 9.
And output to the microcomputer 1. The microcomputer 1 performs feedback control of the motor drive circuit based on the output of the position encoder 9 so that the subject image is formed on the film in a focused state.

Next, a distance measuring method by the distance measuring sensor 3 in the present embodiment will be described. FIG. 2 shows the distance measuring sensor 3.
Shows the relationship between the distance measurement area 21 and the imaging position on the line sensor. In the present embodiment, for example, three distance measurement areas of an L area 21L, a C area 21C, and an R area 21R exist on the imaging area 21, and the L sensor 12b
There is a reference area A on the top, and a reference area B on the R sensor 12a.

The C area 21C is located at the center of the photographing area 21, and the subject in the C area 21C forms an image on the reference area A1 of the L sensor 12b by the separator lens 11b, and the reference area of the R sensor 12a by the separator lens 12b. An image is formed on B1. The reference area B can be moved on the line sensor by a shift operation.

The shift amount (movement amount) of the reference area B
Each time it is performed, the degree of correlation between the data of the L sensor 12b in the reference area A and the data of the R sensor 12a in the reference area B is calculated. By obtaining a shift amount having a high degree of correlation, an interval between two subject images formed on the L sensor 12b and the R sensor 12a can be detected.

Similarly, the reference area A2 and the reference area B2 correspond to the R area 21R, and the reference area A3 and the reference area B3 correspond to the L area. The calculation of the distance to the subject will be described with reference to the flowchart shown in FIG.

First, the on / off state of the release SW is detected (step S1). When the release SW is turned on (YES), the microcomputer 1 instructs the interface circuit 4 to start integration (step S1).
2).

The interface circuit 4 performs an integration operation of a detection signal output from the line sensor 12. When the accumulation level of the detection signal reaches a predetermined value, an end signal indicating the end of the integration operation is transmitted to the microcomputer 1 (step S3).

The microcomputer 1 waits until an end signal is received, and upon receiving the end signal, the A / D converter 13 converts the output levels of the line sensors 12a and 12b output from the interface circuit 4 into digital signals. Is stored in the RAM 14 (step S4).

In this embodiment, the line sensor 12
If the number of stored data reaches 160, for example, the output is repeatedly stored in the RAM 14 to the line sensors 12a and 12b until the number of stored data reaches 160 (step S5).

When the number of stored data has been reached (Y
ES), necessary calculation parameters are set prior to performing distance calculation on the L area 12b which is one of the distance measurement areas (step S6). These parameters are E
It is stored in the EPROM 5.

Therefore, when it is desired to change the size of the distance measuring area or the position on the photographing area, it can be easily changed only by correcting these parameters. FIG. 4 (a)
The positional relationship between each parameter and the line sensor will be described with reference to FIG.

The parameter el indicates the number of data obtained by A / D converting the detection signals of the line sensors 12a and 12b included in the reference area A and the reference area B. Parameter Smax
Is the maximum value of the movement amount of the reference area B, that is, the number of shift operations. The larger the parameter Smax is, the wider the distance measurement range is. When the shift number is “0”,
If the degree of correlation between the reference area A and the reference area B is the maximum, it indicates that the subject exists at the ∞ (infinity) position. Therefore, as the number of shifts increases, it means that the subject is closer to the short distance side. In other words, increasing the parameter Smax means that the distance measurement range is wider toward the short distance side.

The parameter addl indicates the position of the first data of the reference area A. Specifically, it corresponds to one of the addresses of the A / D converted data stored in the RAM 14.

Similarly, the parameter addr indicates the position of the head data of the reference area B. That is, as shown in FIG. 4A, the parameter addl is
b is an address at which data corresponding to L21 on the line sensor 12a is stored, and the parameter addr is R
11 is the address where the data corresponding to 11 is stored.

After setting these parameters, a subroutine "distance calculation" is executed (step S7).
Here, the subroutine "distance calculation" will be described with reference to the flowchart shown in FIG. First, the shift number (s) is cleared (= 0) and initialized (step S2).
1). Next, in order to calculate the degree of correlation between the reference area A and the reference area B, the following known correlation equation is used.

[0033]

(Equation 1) Is calculated (step S22). This correlation expression indicates the data of the line sensors 12 corresponding to the two ranging areas by the sum of the absolute values of the differences. The smaller this sum is, the higher the correlation is. When the calculation of the correlation equation for the shift number (s) = 0 is completed, the shift number (s) is incremented (+1) (step S23).

Then, the operation is repeated to determine whether or not the shift number has reached the parameter Smax of "10" (step S24). In this determination, if the shift number (s) has not yet reached, that is, is 10 or less (NO), the reference area B is shifted, the process returns to step S22, and the degree of correlation is calculated using the correlation equation. However, if the number of shifts (s) has reached 10 (YES), the shift number with the maximum correlation, that is, the shift number with the minimum correlation formula, is selected from among them (step S25).

FIG. 6 shows, as an example, a state where the correlation equation becomes minimum when the shift number (s) is "5". Since the resolution is not sufficient with only the shift number (s), the correlation is maximized by performing an interpolation operation based on the calculation results of the correlation expressions of F (4), F (5), F (6), and F (7). The shift number Sx is obtained (step S25).

The calculated shift number Sx, the focal length (f) of the separator lenses 11a and 11b shown in FIG. 2, and the base line length (b) which is the distance between the separator lenses 11a and 11b.
Is determined based on the distance (L) (step S2).
6). Here, returning to step S8 of the main routine,
The obtained distance data is stored in the RAM 14 as distance measurement data of the L area 21L (step S8).

Next, calculation parameters are set before calculating the distance for the C area 21C (step S).
9). The size of the distance measurement area of the C area 21C is equal to that of the L area 21L described above. Therefore, the value of the parameter el becomes the same. Since the distance measurement area is located at the center of the photographing area 21, the positions of the reference area A and the reference area B must be moved.

Then, the parameters addl and addr are changed. First, in the C area 21C, it is necessary to extend the distance measurement range with respect to surrounding distance measurement areas (L area 21L and R area 21R). In the center of the photographing area 21, there is a high probability that a subject that the user intends to photograph exists. Therefore, it is desirable that the distance measurement range is also wider than the peripheral distance measurement area.

Therefore, the parameter Smax is set to twice the set value. This clarifies the relationship between the set parameters and the position of the line sensor with reference to FIG.

When such parameter setting is completed, the process proceeds to a subroutine "distance calculation" (step S).
10). This subroutine is the same as the distance calculation shown in FIG. 5, and a description thereof will be omitted.

Then, the calculated distance data is stored in C area 2
The data is stored in the RAM 14 as 1C distance data (step S11). Next, parameters required for calculation are set before calculating the distance to the R area 21R (step S12). The parameters of the R area 21R are almost the same as the parameters of the L area 21L set in step S6. According to the position of the R area 21R, the parameter addl and the parameter addr are set to values different from those of the L area 21L. The relationship between the set parameters and the position of the line sensor becomes clear by referring to FIG.

When such parameter setting is completed, the process proceeds to a subroutine "distance calculation" (step S).
13). This subroutine is the same as the distance calculation shown in FIG. 5, and a description thereof will be omitted.

Then, the calculated distance data is stored in the RAM 14 as distance data of the R area 21R (step S14). Next, an optimum one is selected from the distance data of the three distance measurement areas stored in the RAM 14 (step S15).

Various methods for this selection have already been proposed, and any of these known methods may be used. Since this is different from the gist of the present invention, the specific description here will be omitted. Omitted.

Then, based on the selected distance data, the amount of movement of the photographing lens 6 is calculated, the lens motor is driven (step S16), and the process shifts to the exposure operation via a normal operation, for example, a photometry operation.

As described above, in the present embodiment, the correlation calculation is performed while shifting the sampling range of the ranging area on the line sensor, and the subject distance for each ranging area is obtained. At that time, in normal shooting, the subject is often located at the center of the shooting area. Therefore, the shift amount of the sampling range of the distance measuring area set at a position other than the center (peripheral portion) of the photographing area is set to be smaller than the shift amount of the distance measuring area set at the center of the photographing area.

As a result, the number of calculations in the distance measurement area other than the center of the photographing area can be reduced, and the calculation time can be shortened. In the present embodiment, three distance measurement areas are set, and a subject existing in any one of the distance measurement areas is focused on a film to form an image. still,
In the present embodiment, three ranging areas are set on the shooting area. However, the present invention is not limited to this, and it is possible to cope with a case where the ranging areas increase.

Normally, as the number of distance measurement areas to be set is larger, the number of calculations of the correlation formula of each distance measurement area increases. Therefore, reducing the number of shifts in order to reduce the number of calculations in the ranging area other than the center of the photographing area is an effective measure for shortening the calculation time.

While the above embodiments have been described, the present invention includes the following inventions. (1) In a multi-point distance measuring device capable of performing a distance measuring operation on a plurality of distance measuring areas including a central portion and a peripheral portion, a pair of subject images formed via a pair of light receiving lenses are respectively received. One photoelectric conversion means for outputting a subject image signal corresponding to a pair of subject images, and an operation for obtaining a correlation value while relatively moving the subject image signal from the photoelectric conversion means corresponding to each ranging area. And calculating means for calculating the subject distance based on the result, and controlling the calculating means such that the calculated moving distance to the peripheral distance measuring area is smaller than that of the central distance measuring area. A multi-point distance measuring apparatus comprising: (2) In a multi-point distance measuring apparatus of a phase difference detection method having a plurality of distance measuring areas respectively arranged at a central part and a peripheral part of a distance measuring target area, a shift calculation range for a specific distance measuring area is changed. A multi-point distance measuring device set to be larger than a shift calculation range for the distance measuring area. (3) In a multipoint distance measuring apparatus of a phase difference detection method having a plurality of distance measuring areas respectively disposed at a central portion and a peripheral portion of a distance measuring target area, a defocus detection range for a specific distance measuring area is A multi-point distance measuring device characterized by being set to be larger than a defocus detection range for another distance measuring area.

[0050]

As described above in detail, according to the present invention, in a passive phase difference type camera system capable of performing a distance measurement operation for a plurality of distance measurement areas, a shift operation is performed to shorten a distance measurement operation time. It is possible to provide a multi-point distance measuring device with an improved calculation method.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of an embodiment according to a multipoint distance measuring apparatus according to the present invention.

FIG. 2 is a diagram showing a relationship between a distance measuring area in a distance measuring sensor and an image forming position on a line sensor.

FIG. 3 is a flowchart of a main routine for explaining calculation of a distance to a subject.

FIG. 4 is a diagram for explaining a positional relationship of a distance measurement area on a line sensor according to each parameter.

FIG. 5 is a flowchart of a subroutine for explaining distance calculation in FIG. 3;

FIG. 6 is a diagram illustrating an example of the relationship between the number of shifts and the amount of shift in a correlation equation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Microcomputer 2 ... Subject 3 ... Distance measuring sensor 4 ... Interface circuit 5 ... EEPROM 6 ... Shooting lens 7 ... Lens motor 8 ... Motor drive circuit 9 ... Position encoder 11a, 11b ... Separator lens 12 ... Line sensor 12a ... L sensor 12b ... R sensor 13 ... A / D converter 14 ... RAM

Claims (3)

[Claims] 1. A distance measuring area having a plurality of distance measuring areas respectively disposed at a central portion and a peripheral portion of a distance measuring target area, and detecting a distance between a pair of subject images formed by a pair of image forming lenses. hand,
A multi-point distance measuring apparatus that obtains a distance to a subject in the ranging area, wherein a shift calculation range in a correlation calculation for detecting an interval between the pair of subject images is different from the central part and the peripheral part. A multi-point distance measuring apparatus characterized in that: 2. The multi-point distance measuring apparatus according to claim 1, wherein a shift calculation range in the correlation calculation is set to be narrower in the peripheral portion than in the central portion. 3. A plurality of distance measurement areas respectively disposed at a central portion and a peripheral portion of a distance measurement target region, and based on incident positions of a plurality of subject images formed through at least a pair of light receiving lenses. A multi-point distance measuring device for obtaining a subject distance for each of the distance measurement areas, wherein the plurality of formed subject images are respectively received and photoelectric conversion means for outputting respective subject image signals; Calculating means for performing a correlation operation on the paired signals corresponding to the plurality of distance measurement areas while shifting the mutual sampling ranges, to obtain a subject distance for each of the distance measurement areas; The shift amount of the mutual sampling range in the calculating means with respect to the peripheral distance measuring area is set to be smaller than the shift amount with respect to the central distance measuring area. Multi-point distance measuring device characterized by the following.