JPH10153409A - Range finding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to precisely focus a camera or video by switching the range finding range by arithmetic processing using the correlation value of a prescribed part of a subject signal sequence obtained by a pair of light receiving element trains having a parallax. SOLUTION: In the passive type range finding device used for camera, first, a correlation area such as sensor array is designated (S1), and a correlation operation for examining slippage by sensor pitch unit is performed (S2) to provide a correlation result S. When S is larger than a prescribed value S1 , it is judged that a subject is near (S3), and an interpolation operation for calculating the slippage by finer resolution is performed in a wide area (S16) to calculate the distance (S11). When S is smaller than a prescribed value 31, the interpolation operation is performed in a prescribed method with respect to a narrow correlation area (S4-8). When the operation result does not satisfy a prescribed condition, S is corrected (S13-15), and the procedure is returned to S3. When the prescribed condition is satisfied, the distance is calculated according to the operation result (S10-11), and focusing is performed (S12).

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 used for a camera, a video, and the like, and more particularly to a technique for providing a device capable of more accurate distance measurement and focusing.

[0002]

2. Description of the Related Art In general, a distance measuring device used for a camera or the like often uses light. For example, an "active type" in which a signal light is projected from the distance measuring device side and a luminance distribution image of an object are used. The method is roughly divided into "passive type". Both of these methods use triangulation as the basic principle. In the active type, the distance between the light emission and the light reception is set to the basic length (that is, the base line length). The distance to the object is determined according to the relative position difference between the images of the object. Since it is necessary to measure the amount of light at each light receiving position in order to observe the image of the object, a line sensor formed by arranging a plurality of optical sensors is used.

First, a distance measuring method of the passive type distance measuring device will be described with reference to FIG. Reference numerals 1a and 1b denote two light receiving lenses which are arranged apart from each other by a base line length B. Light incident from the subject 6 through these lenses forms light patterns as shown by curved patterns 3a and 3b on the line sensors 2a and 2b, respectively. Patterns 3a and 3 obtained depending on the relative positional relationship between the light receiving lenses of
The relative position difference x of b is the distance f between B and the lens and sensor.
And the subject distance L. That is, the following relationship is established. x = B × f / L (Equation a) A method of calculating the relative position difference from the output of the line sensor by calculation (hereinafter, referred to as correlation calculation) is disclosed in Japanese Patent Publication No. 7-54371. Have been.

It is also an important technique to determine which part of the light pattern is used to measure the distance. For example, as shown in FIG. 5, even if an attempt is made to measure a person 6a as shown in FIG. When the light incident on the portion is taken into account, the luminance of the background mountain 6b in the distance is mixed (this is referred to as mixed distance), and correct distance measurement cannot be performed. That is,
In the figure, a technique for using only the light incident on the sensors R1 to Rn1 but not using the sensor signal of Rn2 is necessary for correct distance measurement. As a proposal of such a technique, Japanese Patent Publication No. 5-88445 is known.

[0005]

However, the technique disclosed in Japanese Patent Publication No. 7-54371 discloses the above-mentioned "mixed distance".
Does not mention the issue of
In the technology disclosed in Japanese Patent Laid-Open Publication No. H11-264, after the correlation operation, the area of the sensor is switched when the result is inappropriate, and because of the extra time required and the need to reprocess the data many times, The determination and calculation using a microcomputer (hereinafter abbreviated as a microcomputer) also have problems such as an increase in memory capacity and program capacity.
That is, even if these conventional techniques are simply combined, it is difficult to provide a high-speed and high-accuracy distance measuring device.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and appropriately switches the range of a passive-type distance measuring apparatus, thereby enabling high-speed calculation without measuring unnecessary areas. It is an object of the present invention to provide an accurate distance measuring apparatus when it is applied to, for example, focusing of a camera or a video.

[0007]

Accordingly, the present invention employs the following means in order to solve the above-mentioned problems and achieve the object. That is, [1] light receiving means for receiving a subject image by a pair of light receiving element rows having parallax and outputting a pair of subject image signal rows; A correlation means for outputting a correlation value of the first portion of the above, a subject image signal sequence of all the light receiving element rows of one of the pair of light receiving element rows, and a subject image signal sequence of the other light receiving element row. A distance measuring apparatus including data input means for selectively inputting only partial data of a second portion narrower than the first portion, and interpolation means for performing a predetermined interpolation operation based on the input data. provide. [2] Light receiving means for receiving a subject image by a pair of light receiving element rows having parallax and outputting a pair of subject image signal rows, and converting the pair of subject image signal rows into a plurality of pixels having a first number of pixels Means for dividing into blocks, correlating means for receiving the output of the light receiving means and outputting a correlation value of the pair of subject image signal strings, and, when the correlation value satisfies a predetermined condition, dividing the block into a first pixel Means for resetting the number of pixels to a second number of pixels smaller than the number of the pixels, and all the subject image signal rows of one of the pair of light receiving element rows and the subject image signal rows of the other light receiving element row. The present invention provides a distance measuring apparatus including a data input unit for selectively inputting only the data of the second pixel number and an interpolation unit for performing a predetermined interpolation operation based on the input data. [3] Two line sensors that output two light pattern signals in accordance with the luminance distribution of the subject image observed from different visual fields having parallax, and compare the two light pattern signals based on the parallax of the subject image. A pitch difference calculating means for calculating a relative position difference in units of an array pitch of the line sensor; and an output signal of the line sensor based on an output result of the pitch difference calculating means. Calculation control means for calculating the relative position difference of the light pattern with an accuracy finer than the sensor pitch,
The pitch difference calculating means is constituted by a hard logic circuit, and the arithmetic control means is constituted by a microcomputer and software.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A plurality of embodiments according to the present invention will be described below with reference to the accompanying drawings. (First Embodiment) A method of calculating a relative position difference between light patterns in a passive type distance measuring apparatus according to the present invention will be described first with reference to FIGS. 1 (a) and 1 (b). FIG.
In (a), the difference B between the positions of the light receiving lenses 1a and 1b
Due to the (base line length), the relative position difference x of the light distribution incident on the sensor arrays 2a and 2b changes depending on the subject distance L. Assuming that the focal length of each light receiving lens is f, the subject distance L is obtained by the following equation. L = B × f / x (Equation b) Since each sensor of the sensor array outputs a current signal according to the amount of incident light, if these are converted into a digital signal by the A / D converter 4, image shift occurs. The relative position difference x can be detected by the correlation calculation by the calculation unit 5 that calculates the amount. The object distance L is obtained by inputting the result to an arithmetic control means (CPU) 10 comprising a one-chip microcomputer or the like and calculating based on the above equation b. The above is the basic principle of the passive type triangulation and the general device configuration.

The above-described shift amount calculation function generally includes two processes as described later.
May be built in as a control program. When the camera is focused using such a technique, the CPU 10 controls the operation of the camera, and if the lens for photographing is appropriately controlled through an actuator such as a motor, an automatic focus (AF) function is provided. With camera can be provided.

In order to calculate the amount of image shift, an operation step (that is, a correlation operation) for checking how much the image shifts in units of sensor pitch in both line sensors is required. Then, an operation step (hereinafter, referred to as an interpolation operation) for calculating the shift amount more precisely with a finer resolution is required. When light is incident on the sensor array 2a in a pattern like a waveform 3a shown in FIG.
The magnitude of the output of each of the sensors R1 to R6 has a distribution 3a as shown by a bar graph in FIG. Where "
"R" indicates the right sensor, "L" indicates the left sensor,
Assuming that the suffixes 1 to 6 appended thereto indicate, for example, the absolute position of the sensor with respect to the optical axis of the light receiving lens, the same signals as the outputs R1 to R6 are output from the outputs L1 to L6 of the left sensor. In this case, since the relative position difference x is 0, the subject distance L to be obtained is “infinity”. Also,
When the subject exists at the “finite distance”, the output R as shown in FIG. 2C is applied to the left sensor L shifted by the number S of sensors determined from the x and the sensor pitch SP.
Output signals having values similar to 1 to R6 are obtained.

The value FF on the vertical axis in the graph of FIG.
(i) is obtained according to the following equation. FF (i) = Σ | R (i) −L (i) | (Expression c) That is, the output of the corresponding L sensor is subtracted from the output of a certain R sensor, and the absolute value is calculated for each sensor. The result of the addition may be FF. That is, first, Li is subtracted from Ri to obtain the absolute value, i is changed in a certain width, and these are added.

Next, one of the sensors Ri and Li is set to 1
If the difference is taken in the same way as the adjacent sensor which takes the difference first by shifting the unit, FF (i + 1) can be expressed by the following equation. FF (i + 1) = Σ | R (i + 1) −L (i) | (Equation d) As described above, the shift amount (hereinafter, referred to as SIFT amount)
Can be obtained while changing the amount of SIFT, where the SIFT amount at which the FF, which is the sum of the difference between R and L, has the minimum value (Fmin) is considered to be the position where the best correspondence is obtained. The SIFT amount is obtained as S. The above is the schematic procedure of the process regarding the correlation operation.

FIG. 2B shows the output distribution of both sensor arrays taking the above S into consideration, as shown in FIG.
Outputs similar to those of the R-side sensors with corresponding suffixes are obtained from the respective sensors shifted by only a certain amount.

Next, the "interpolation operation" process will be described in detail with reference to FIGS. 2 (b) to 2 (d). The actual image shift amount on the two sensor arrays is not exactly shifted by the sensor pitch. For accurate distance measurement, the amount of image shift must be detected with an accuracy smaller than the pitch. Therefore, an interpolation operation is performed. R in FIGS. 2B and 2C
And L represent the outputs of some of the sensors constituting the sensor arrays 2a and 2b in FIG. FIG. 2D shows a graph obtained by shifting the S by which the “correlation calculation” has already been completed, and then converting the S to a state where comparison is easy. That is, L0 to L4 should be accurately described as Ls to Ls + 4, but this S is omitted to avoid complication in description. Here, it is assumed that light shifted by x on the R reference is still incident on the L sensor after shifting by S. At this time, for example, the light incident on R0 and R1 is mixed and incident on the L1 sensor, and similarly, the light shifted by x with respect to the R reference is sequentially incident on each L sensor. It can be seen that the outputs (L1 to L3) are represented as shown in [Equation 1] of FIG.

The above-mentioned Fmin and the FF values F-1 and F-1 obtained by shifting the shift amount from Fmin in the plus direction and the minus direction.
When +1 is expressed using the outputs of Rn and Ln, it is expressed as [Equation 2] in FIG. Further, when [Expression 2] is expanded using [Expression 1], each of the values Fmin, F-1, and F + 1 is expressed as [Expression 3] in FIG. Also,
｛| R0−R1 | + | R1−R2 | +
If | R2 -R3 | と し て is expressed as (ΣΔR), the aforementioned deviation amount x is obtained by the calculation shown in [Equation 4] of FIG. 18 without depending on (ΣΔR). This is the "interpolation operation".

Although these calculations are performed by the calculation means 5 in FIG. 1, they may be performed by a calculation control means (CPU) 10 such as a one-chip microcomputer according to a predetermined program.

An outline of the above-described calculation process can be represented as shown in the flowchart of FIG. That is,
First, it is specified which area of the sensor array is to be used to perform the above “correlation calculation” using light (S101). next,
“Correlation calculation” described with reference to FIG.
Is performed to determine the shift amount (S102). Further, from the result, “x” is further obtained by performing “interpolation operation” described in [Equation 4] (S103).

Based on the values S and x thus obtained,
If the CPU 10 calculates and controls the extension amount of the focusing lens, an autofocus (AF) camera can be provided. Note that this operation means can also be constituted by a logic circuit, but as described above, these operations are performed by CP without using such hardware operation means.
This may be performed according to a predetermined program incorporated in U10. Such a case is represented by a flowchart as shown in FIG. That is, the output of each sensor of the sensor array is input by the CPU 10 (S105), and the CPU 1
0 performs the above-described correlation operation (S106) and interpolation operation (S107) by a predetermined program,
The amount of extension of the zoom lens or the like is calculated based on the result, and focus control is performed (S108).

The arithmetic operation by a logic circuit (ie, a hard logic circuit) can reduce the scale of the circuit and increase the speed, but it is difficult to judge the data contents and switch the width of the distance measurement area. It is. On the other hand, such control is possible by the microcomputer control, but has the advantages and disadvantages that it is difficult to increase the speed.

For example, in a scene of a person and a mountain as shown in FIG. 4, in order to correctly measure the distance of the subject 6a (person), the distance measurement area W is preferably smaller than the width K of the person's face. That is, the relationship of W <K holds. The reason is that, as the distance measurement area W is larger, even the light information of the background mountain 6b is added to the calculation, so that it is difficult to perform a highly accurate distance measurement (that is, because of the occurrence of a mixed perspective error). Accuracy will decrease).

The distance measuring area W depends on the pitch SP of the sensor array, the number E of sensors to be used, the distance L, the distance f between the sensor and the lens, and the following relationship is established. W = L × SP × E / f (Equation e) As can be seen from this relationship, the width K of the face is constant with respect to the distance L, whereas the distance measurement area W is proportional to the distance L. In other words, even if the distance L to the subject changes, the SP and f are constant in order to keep the distance measurement area W equal to or less than the face width K, so that there is only a method of switching the number E of sensors. On the other hand, if there is no mixed perspective, the wider the correlation area, the higher the accuracy because the noise of the sensor is canceled. Therefore, in short-range shooting, a wider correlation area is advantageous. Thus, it is better to make the width of the ranging area variable.
Distance measurement can be performed with high accuracy over a wide range from a short distance to a long distance.

However, the problem of the mixed perspective is often caused at the level of the interpolation operation, and has little influence on the correlation operation. Therefore, in the first embodiment of the present invention,
Correlation calculation that does not cause a large error even if it is composed of a relatively simple logic circuit or has mixed perspectives is performed by a high-speed hard logic circuit, while interpolation calculation to be performed with strict accuracy is performed by software using a CPU. It is configured to perform precisely by the operation according to the wear. As a result, a distance measuring device that achieves both high speed and high accuracy can be realized.

FIG. 3C shows a flowchart of FIG.
Compared with the flowchart of FIG. 3A and the flowchart of FIG. 3B, the procedure relating to the arithmetic processing as the first embodiment of the present invention is shown. That is, the arithmetic processing is controlled as shown in FIG. 3C to achieve both high speed and high accuracy. First, a correlation area is specified (S109), and a correlation operation is performed by a hard logic operation circuit (S110). Based on the resulting correlation value S, the CPU 10 reads the data of the sensor array (S111), and performs software-based interpolation calculation by the microcomputer (S112). The extension amount of the zoom lens is calculated based on the obtained result, and appropriate focus control is performed on the subject (S113).

(Modification 1) According to the object of the present invention, it is not always necessary to perform the correlation operation by a hard logic circuit. If the speed can be increased, for example, by reducing the number of data in the area to be correlated, FIG. Step S106 of b)
Alternatively, it may be performed by software. Similarly, regarding the interpolation calculation, step S1 in FIG.
03 may be performed by hardware. In any case, in the correlation operation and the interpolation operation, the data used or the work area is separately used to increase the processing speed and accuracy.

Here, for example, if the correlation of a simple light and dark light pattern is obtained in units of sensor pitch, this function can be satisfied even with the circuit configuration shown in FIG. Behind the optical axis of the light receiving lens 1a, sensor arrays 20a, 21b
Are arranged, and arrays 20b and 2 are arranged behind the light receiving lens 1b.
1b and 22b are arranged, and 3a and 3b, respectively.
Let us consider a case where light having a light quantity distribution having a waveform as shown in FIG. The transistors 23 and 24 form a current mirror circuit, and the photocurrent of the sensor 20a becomes the collector current of the transistor 24. Therefore, the photocurrent of the difference between the sensors 20a and 21a is input to the amplifier 28 that follows, and when the photocurrent of the sensor 20a is larger than the photocurrent of the sensor 21a, the difference current flows into the amplifier 28. ,
If the magnitude relation is reversed, a difference current flows out of the amplifier 28. In other words, the amplifier output becomes L (Low) or H (High) depending on the magnitude relation.

Similarly, the sensor on the side of the lens 1b is also connected to the current mirror circuit of the transistors 25, 26 and 27, and the amplifier 2 is connected to the output of the sensor 21b.
Since the difference photocurrent flows into and out of the sensors 9 and 30, the outputs of these amplifiers become H (High) or L (Low) in the same manner as the amplifier 28 depending on the brightness on the sensor array. Or

The amplifier 29 becomes L when the photocurrent of the sensor 21b is larger than that of the sensor 20b.
2 is input. In addition, the sensor 21b is
When the photocurrent is large, the output of the amplifier 30 becomes L. When this is input to the AND circuit 33, when the magnitude relation of the optical pattern on the lens 1a side becomes equal on the sensors 20b and 21b, , AND circuit 32 is connected to the sensor 21
b and 22b, the AND circuit 33 outputs
An H signal is output. With the above-described configuration, it is possible to determine where the change in the light and dark pattern occurs in the sensor array in a logic circuit manner. A simple correlation operation is also possible by making such a circuit complicated as hardware.

FIG. 6 shows the structure of a camera as a specific example of the embodiment of the present invention. However, the lenses 1a, 1
measuring unit 1 composed of sensor array 2a, sensor arrays 2a, 2b, etc.
Since 00 has already been described, a detailed description is omitted. Further, the correlation circuit 5 is constituted by a hard logic circuit as described with reference to FIG. The A / D conversion circuit 4 is a circuit for converting an analog output of the sensor array into digital data, and here has a function of storing the converted data. The output circuit 7 outputs the stored data to the CPU 10 by serial communication. This CPU1
0 denotes a port means 19 including a port for serial communication, a terminal for controlling each function of the camera, etc .; a group of registers 14 and 18 for controlling the port; a RAM 15 for temporarily storing data; The ROM 16 stores a program of instructions for controlling these by the above algorithm.

Also, by the port control, the extension control of the focusing lens 13 is performed through the extension control means, and the drive of the shutter 8 and the like is controlled. An electrically writable ROM (EEPROM) 9 for storing a correction coefficient for correcting an error caused by a variation in camera parts or a variation in assembly accuracy is provided, and the CPU 10 refers to the correction data. Control the camera.

Next, the operation of the distance measuring apparatus for a camera having the above-described configuration will be described with reference to the flowchart of FIG. First, a correlation area is specified (S1). Here, A / D conversion is performed by the A / D conversion means 4 on data based on the light pattern incident on the sensor array by designating a correlation area as indicated by R1 to R3 in FIG. Correlation calculation is performed for each sensor pitch by the correlation means 5 in FIG. 6 (S2), and the correlation result S is obtained. Since the value S depends on the distance to the subject, a rough determination of the subject distance can be made by making a determination based on this value (S3).
For example, if it is larger than the predetermined value S1, the subject is considered to be at "near distance" and the process branches to step S16 to perform an interpolation operation on a "wide" area (S16).
Proceed to 1.

On the other hand, in step S3, the predetermined value S
In the case of 1 or less, the process proceeds to step S4 to perform the interpolation calculation in the “narrow” correlation area. More specifically, first, data (R0 to R0) for distance measurement from a sensor on the R side in a predetermined narrow area
4) is read (S4). Next, reading which is one of the features of the present invention is performed. That is, instead of blindly taking in the data on the L side, only the data (L1, L2, L3) used in each calculation formula shown in [Equation 3] is input (S
5). In this method, since the data of the value taking into account the shift amount S with which the correlation is obtained is taken, the microcomputer (C
PU) RAM is not wasted, and the time required for data reading by serial communication can be reduced. From the data thus read, a calculation based on each equation shown in [Equation 2] is performed, and the minimum Fmin and the F-1 on both sides thereof are calculated.
And F + 1 are obtained (S6 to S8).

Next, it is confirmed whether or not a difference has occurred in the correlation value S due to switching of the area range between the correlation calculation and the interpolation calculation (S9). In this determination,
Fmin, obtained by the correlation operation in steps S6 to S8,
It is determined whether or not Fmin has a minimum value among F-1 and F + 1. If Fmin is not the minimum, the process further branches to step S13 to determine the magnitude relationship between F-1 and F + 1. If F-1 is the minimum, S is reduced by one, and F + 1
If is smaller, the correlation value S is increased by one to correct S (S14, S15), and the process returns to step S3.

Subsequently, in steps S10 to S12, interpolation calculation based on the illustrated formula (S10), calculation of the distance L (S11), and focusing on the subject located at the distance L (S12) are performed. It is. Note that the calculation of x in step S16 described above is basically performed only for a wide range of the sensor area.
This is performed in the same manner as in S10. However, the processing step S9 for confirming the magnitude of Fmin again is unnecessary.

Normally, a one-chip microcomputer uses a register 14 for calculation to input / output data and performs calculation in a predetermined order for data calculation. Requires a large amount of time and instructions to calculate by taking data in and out of the data one by one. Therefore, the "FF operation" as shown in FIG. 2C, which takes the difference between R and L data while shifting the data little by little and adds over a predetermined area, is a very inefficient process. Become. Moreover, in the subsequent interpolation calculation, as shown in [Equation 4], only Fmin and F-1 and F + 1 on both sides are used, so even if a large number of FFs are calculated, highly accurate measurement is possible. It doesn't mean you can do it. This corresponds to the R provided as shown in FIG.
Although the load is heavy for the capacity of the OM 16, it is a big problem in terms of the RAM capacity for temporarily storing data.

Therefore, FIG. 8B illustrates a usage mode of the RAM according to the present embodiment in comparison with a usage mode of the RAM of the conventional distance measuring apparatus shown in FIG. 8A. As shown in the figure, in contrast to the conventional case where much of R0 to R4, L0 to L4 + S,... Had to be calculated, in the present invention, R0 to R3, L1 + S, L2 + S, L3 It can be seen that the calculation of only + S is sufficient, and that the memory space can be saved, and the effect of reducing the space used such as the RAM is large.

(Function and Effect 1) As described above, according to the present embodiment, high-speed and high-precision, that is, the influence of mixed perspective is small, and the program in the CPU and the memory space used are reduced. A distance measuring device having an effect can be provided.

(Second Embodiment) Next, a second embodiment according to the present invention will be described. The distance measuring device of the present embodiment is also implemented in the device configured as shown in FIG. The feature of this embodiment is that the left and right R and L sensor arrays
This is one embodiment for coping with an offset error as described above, and the flowchart of FIG. 9 illustrates details of a characteristic calculation process of the present embodiment as described later.

FIG. 11 is a graph showing the output of each sensor corresponding to FIG. 2D. As illustrated, L
When it is considered that R has an error of C11, C22, and C33 on each sensor, it is preferable that the correlation calculation and the interpolation calculation be performed after correcting these. However, when this error is small, it is possible to accurately perform the correlation calculation using the sensor pitch as “resolution”. Therefore, in the second embodiment of the present invention, this correction is performed prior to the interpolation operation, the interpolation is performed accurately, the number of correction coefficients is minimized, and this is stored.
It is possible to reduce the capacity of the EPROM. Further, since such an error tends to have an effect when the distance measurement area is small, the above correction is performed only when the interpolation calculation is performed in a narrow area, thereby further reducing the correction coefficient.

As shown in FIG. 10A, as shown in the graph of FIG.
Analyzing a photograph taken in general, a person rarely becomes a subject at a distance longer than a certain distance L1. On the other hand, as shown in FIG. 4, it is not necessary to reduce the area particularly at a distance longer than a certain distance L2. Therefore, it is possible to design such that it is sufficient to correct the sensor error only when measuring the distance of the subject located at the distance from L1 to L2. This rough distance judgment is
It can be predicted to some extent by the correlation operation result S. Therefore, in the flowchart shown in FIG.
This is a specific example designed on the assumption that the correlation value S of the subject located at the distance of takes a value between predetermined S2 and S1.

Steps S1 to S5 in FIG. 9 are the same as those in the flowchart of FIG. 7 of the first embodiment already described. However, for the reason described above, in step S3, when the correlation value S is between S1 and S2 (that is, S2 <S <
Control is performed so that distance measurement is performed in an area narrow only by S1). Reading of R side sensor data (R0 to R4) (S4)
Following the reading of the L-side sensor data (LS + 1 to LS + 3) (S5) following step S5b, in step S5b, L1 and L2 of FIG.
, L3, R1, R2, R3 errors C11, C22, C3
In this step, a correction coefficient such as 3 is read from the EEPROM. In steps S6 to S8, the errors between Rn, Rn-1, Rn + 1 and Ln (errors that do not result in the same output when the same luminance is viewed) Cnn, Cn (n-1),
This is a step of calculating Fmin, F-1, and F + 1 while correcting Cn (n + 1). Fmin, F-1, F + 1 thus obtained
Thus, x is obtained by interpolation as in step S10 in FIG. 7, and focusing is performed (S12).

(Function and Effect 2) With the above configuration, the memory capacity of the correction coefficient conventionally required for each of the R and L sensors as shown in FIG. Then, the memory capacity can be reduced as shown in FIG. Therefore, according to the present embodiment, the subject distance can be determined using the correlation result S obtained in advance at a high speed, and error correction can be performed with emphasis on a person at a predetermined long distance. And the number of correction programs and memories can be reduced.

Third Embodiment Next, a third embodiment according to the present invention will be described. The distance measuring apparatus of this embodiment is also implemented by the apparatus configured as shown in FIG. The feature of the present embodiment is that, as shown in FIGS. 12A and 12B, a state in which a part of the distance measurement area deviates from the person 6 is detected. In this case, the distance measurement is performed excluding the deviated sensor. This is an embodiment for taking measures against the mixed perspective error described with reference to FIG. 4 by performing calculations. Since the distance measurement area is not excessively narrowed as compared with the first and second embodiments described above, even higher distances can be obtained for objects larger than a human face even at a long distance. This is an embodiment that enables distance measurement. In a photographing scene as shown in FIG. 12B, a sensor deviating from the subject has a poor correlation, so that the difference | Rn-L as shown in the graph of FIG.
The result of n + s | has a different value compared to the sensor corresponding to this subject. Using such a principle, FIG.
In the example of (a), the difference F between the central sensors R2 and Ls + 2
c Interpolation operation is performed by removing the sensor output above. In order to provide such a function, a program having the algorithm of the flowchart shown in FIG. 13 is built in the CPU.

Steps S1 to S5 are the same processing steps as those already described. Subsequently, Fmin, F-1, F + 1, etc. for the interpolation operation are initialized to 0 (S20), and 2 is substituted for i to select the center sensor (S2).
1) Read Ri, that is, the data of R2 (S2)
2). The difference Fi is obtained (S23), and the obtained difference is set as a reference value Fc of the difference (S24). Since the sum of the difference for each sensor is Fmin, this is added to Fi (S2
5). In the subsequent calculation step groups, F + 1, F-1
In order to find the difference, Ri + 1 and Ri-1 are read out, the difference from Li is found, and F + 1 and F-1 are calculated (S26 to S29).

Next, in steps S30 to S34, i is decremented by one (S30), and Ri, Ri + 1, Ri-1 are read out for the sensor with the smaller number on the left side from the center (S31), and Li and Ri are read. Are calculated, and F + 1 and F-1 are calculated (S32). Here, when the difference Fi between Ri and Li greatly deviates from the reference value Fc, the calculation processing (S
34), the magnitude relationship with the reference value Fc is determined so that those not removed from the target and those not deviated are taken into account (S3).
3).

Similarly, also in steps S35 to S40, for the sensor i whose number is increased by one on the right side from the center (S
35, S36), and read Ri, Ri + 1, Ri-1 (S35).
37), the difference from Li is calculated, and Fmin, F + 1, and F-1 are calculated (S38).
, Li are determined to have a magnitude relationship with the reference value Fc (S39) so that those whose difference Fi greatly deviates from the reference value Fc are excluded from the calculation processing (S40). Interpolation is performed by using the interpolation calculation Fmin, F-1, and F + 1 obtained in this way to obtain x (S10), and then the distance L is determined and focusing is performed (S12). A series of processing ends.

(Function and Effect 3) As described above, in the third embodiment, it is possible to take measures against a mixed error of distance and distance, and in the case of a subject other than a person, it is possible to increase the distance measurement area.
By selecting the optimal ranging area for the subject, more precise focusing is possible.

(Other Embodiments) The first embodiment exemplified above
In the third to third embodiments, the case where a hard logic circuit is used as the means for obtaining the correlation amount S in the unit of the sensor pitch has been described as an example. However, this means is a software means that the microcomputer performs calculation using a predetermined program. However, application is possible. Therefore, a specific example in this case is shown in a flowchart in FIG. This processing procedure is a process for obtaining the correlation amount S, in which the minimum value of the FF described with reference to FIG. 2 is “FF1”, and the shift amount on the horizontal axis of the graph is “SFT”. Further, n is an integer representing the number of the sensor.

First, FF1 is initialized to 100 (S5).
1), SFT, n, FF are initialized to 0 (S5)
2). Subsequent steps S53 to S56 are a difference calculation processing loop. That is, the difference FF1 is calculated (S
53), and adds the obtained difference to the FF (S54).
After incrementing the sensor number n by one (S55),
The repetition of this processing loop is determined by comparison with a predetermined limit number nc (that is, the number of target areas) (S56).

When the sum of the differences for each sensor is obtained as FF by the above processing loop, next, the magnitudes of FF and FF1 are compared (S57).
F is substituted for FF1 (S58), and SFT is substituted for S (S59). After incrementing the SFT by one (S60), the process returns to step S53 and repeats the above steps until a predetermined limit value Smax is reached. When it reaches Smax, the process proceeds to step S3 in FIG.

(Function and Effect 4) As described above, the means for obtaining the correlation amount can be realized by software means using a program consisting of steps S51 to S61. As is clear from this flowchart, if the number of target areas nc for adding the correlation is small, the number of times the processing loop is repeated is reduced, and the speed can be increased. Further, since the correct S value is obtained even if the correlation calculation in the pitch unit is somewhat rough, further higher-speed processing can be performed than the calculation processing without area switching as shown in FIG.

(Other Modifications) The present invention can be variously modified as a method of realizing the present invention without departing from the gist of the present invention.

Although the embodiments have been described above, the present invention includes the following inventions. [1] A light receiving means for receiving a subject image by a pair of light receiving element rows having parallax and outputting a pair of subject image signal rows, and receiving an output of the light receiving means and receiving a signal from the pair of subject image signal rows. A correlation means for outputting a correlation value of a part 1; a subject image signal sequence of all the light receiving element rows of one of the pair of light receiving element rows; Data input means for selectively inputting only partial data of a second portion narrower than the portion,
An interpolating means for performing a predetermined interpolation operation based on the input data. [2] A light receiving unit that receives a subject image with a pair of light receiving element rows having parallax and outputs a pair of subject image signal rows, and converts the pair of subject image signal rows into a plurality of pixels having a first number of pixels. Means for dividing into blocks, correlating means for receiving the output of the light receiving means and outputting a correlation value of the pair of subject image signal strings, and, when the correlation value satisfies a predetermined condition, the block for the first pixel Means for resetting the number of pixels to a second number larger than the number of the pixels, and all the subject image signal rows of one of the pair of light receiving element rows and the subject image signal row of the other light receiving element row. And a data input means for selectively inputting only the data of the second number of pixels, and an interpolation means for performing a predetermined interpolation operation based on the input data. apparatus. [3] Two line sensors that output two light pattern signals in accordance with the luminance distribution of the subject image observed from different visual fields having parallax, and compare the two light pattern signals based on the parallax of the subject image. A pitch difference calculating means for calculating a relative position difference in units of an array pitch of the line sensor, and an output signal of the line sensor is selected based on an output result of the pitch difference calculating means, and the two signals are selected based on the result. Calculation control means for calculating the relative position difference of the light pattern with finer accuracy than the sensor pitch, wherein the pitch difference calculation means is constituted by a hard logic circuit, and the calculation control means is a microcomputer and software. A ranging device characterized by being configured. The following inventions are also included. (1) Two line sensors that output two light pattern signals in accordance with the luminance distribution of the subject image observed from different visual fields having parallax, and compare the two light pattern signals to determine based on the parallax of the subject image. A pitch difference calculating means for calculating a relative position difference in units of an array pitch of the line sensor; and an output signal of the line sensor based on an output result of the pitch difference calculating means. A distance measuring device, comprising: arithmetic and control means for calculating the relative position difference between the light patterns with an accuracy smaller than the sensor pitch. (2) The distance measuring apparatus according to (1), wherein the pitch difference calculating means is constituted by a hard logic circuit, and the arithmetic control means is constituted by a microcomputer and software. (3) The arithmetic control means includes a storage means for storing the output of the line sensor, and selects one of the outputs of the two line sensors based on an output result of the pitch difference calculating means. The distance measuring apparatus according to (1), wherein a difference from one output is calculated, and control is performed such that the result is stored in the storage means. (4) In the process of calculating the relative position difference between the two light patterns with a finer precision than the sensor pitch, the arithmetic control means compares the difference between the two light patterns, The distance measuring apparatus according to (1), further comprising a function of determining an output result, wherein when it is determined that the output result of the pitch difference calculating means is incorrect, the output result is changed.

(5) Two line sensors that output two light pattern signals in accordance with the accuracy distribution of the subject image observed from different visual fields having parallax, and compare the two light pattern signals to determine the parallax of the subject image. A pitch difference calculating means for calculating a relative position difference based on the unit of the arrangement pitch of the line sensor, and an accuracy finer than the pitch of the relative position difference between the two light patterns based on an output result of the pitch difference calculating means. And a calculation control means for calculating the relative position difference, wherein the calculation control means selects and subtracts the output signals of the two line sensors, and calculates the relative position difference based on the subtraction result. A distance measuring device for determining a sensor portion for calculation. (6) A means for storing the output imbalance correction information of the two line sensors, selecting the output imbalance correction information based on the calculated pitch difference, and correcting the subtraction result. The distance measuring apparatus according to (5), comprising: (7) The two line sensors that output two light pattern signals based on the luminance distribution of the subject image observed from different visual fields having parallax, and the first parts of the two light pattern signals are compared with each other. A pitch difference calculating means for calculating a relative position difference based on the parallax of the subject image in units of a pitch of the line sensor; and a relative position difference between the two light patterns according to an output result of the pitch difference calculating means. Calculation control means for calculating with a finer precision than the above, wherein the calculation control means calculates the relative position difference with a finer precision than the pitch, the calculation result of the pitch difference calculation result A second portion different from the first portion is selected from the two line sensors on the basis of the two line sensors, and the output of this portion is compared to calculate the relative position difference. The distance measuring device to be used. (8) means for storing output unbalance correction information of the two line sensors, and correction of the subtraction result based on the output of the selected position difference calculation second portion and the output unbalance correction information. (7) The distance measuring apparatus according to (7), further including: a correction unit that determines whether the distance is determined.

In addition, the following inventions are also included. (1 ′) Two line sensors that output two light pattern signals according to the luminance distribution of the subject image observed from different visual fields having parallax, and compare the two light pattern signals to obtain a parallax of the subject image. A relative position difference based on the pitch sensor of the line sensor, and an output signal of the line sensor according to an output result of the pitch difference calculator, and the two light patterns according to the result. And a calculation control means for calculating the relative position difference with a precision finer than the pitch of the line sensor. (2 ') The distance measuring apparatus according to (1'), wherein the pitch difference calculating means is constituted by an electronic circuit of hard logic, and the arithmetic control means is constituted by a microcomputer and software. . (3 ′) The arithmetic control unit includes a storage unit that stores the output of the line sensor, selects one output of the two line sensors based on the output result of the pitch difference calculation unit, and selects the other output. The distance measuring apparatus according to (1 '), wherein the difference from the output of the distance measuring device is calculated, and control is performed such that the result is stored in the storage means. (4 ′) In the process in which the arithmetic control unit calculates the relative position difference between the two light patterns with a precision smaller than the pitch of the line sensor, the difference between the two light patterns is compared to calculate the pitch difference. (1 ') has a function of judging an output result of the means, and if the output result of the pitch difference calculating means is judged to be incorrect, the pitch difference calculation result is changed. Distance measuring device.

(5 ') Two line sensors for outputting two light pattern signals according to the precision distribution of the subject image observed from different visual fields having parallax, and comparing the two light pattern signals to obtain the subject image The relative position difference based on the parallax of the pitch difference calculating means for calculating in units of the array pitch of the sensor, the relative position difference between the two light patterns based on the output result of the pitch difference calculating means than the pitch And a calculation control means for calculating with fine precision, the calculation control means selects the output signals of the two line sensors and performs a predetermined subtraction, and based on the result of the subtraction, determines the relative position. A distance measuring device for determining a sensor part for calculating the distance. (6 ') means for storing the output imbalance correction information of the two line sensors, and selecting the output imbalance correction information based on the difference between the calculated pitches and correcting the subtraction result The distance measuring device according to (5 '), further comprising a correcting means.

(7 ′) Two line sensors that output two light pattern signals according to the luminance distribution of the subject image observed from different visual fields having parallax, and the first part of the two light pattern signals is connected to each other. A pitch difference calculating means for calculating a relative position difference based on the parallax of the subject image in units of a pitch of the line sensor; and a relative position of the two light patterns based on an output result of the pitch difference calculating means. A distance measuring device configured to calculate the difference with an accuracy smaller than the sensor pitch, wherein the arithmetic control unit calculates the relative position difference with an accuracy smaller than the pitch of the line sensor; Based on the pitch difference calculation result, select a second portion different from the first portion of the two line sensors, compare the output of this portion, and Distance measuring apparatus characterized by calculating the 置差. (8 ') means for storing output unbalance correction information of the two line sensors, and based on the selected position difference calculation second part, using the output unbalance correction information, The distance measuring apparatus according to (7 '), further comprising a correction means for determining whether to correct the subtraction result.

[0057]

As described above, according to the present invention,
By properly switching the range of the passive type distance measuring device, it is possible to provide a distance measuring device that enables high-speed arithmetic processing without measuring unnecessary areas of the subject. It is possible to provide a photographing device such as a camera and a video, which can perform high-speed focusing at high speed. In addition, as an electronic system capable of high-speed and high-accuracy ranging,
A ranging device for a camera or the like that can be configured with a small storage capacity of a required memory or program can be provided.

[Brief description of the drawings]

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

FIGS. 2 (a) to 2 (d) show the calculation principle of distance measurement according to the present invention, FIG. 2 (a) is a graph showing a relationship between a focus and a shift amount, and FIG. (C) is a graph showing a signal output for each sensor portion of the left sensor L, and (d) is a graph showing a relationship between left and right sensor outputs and outputs of adjacent sensor portions. Graph.

FIGS. 3A to 3C show a procedure comprising a correlation operation and an interpolation operation, FIG. 3A is a flowchart showing a processing procedure by hardware, and FIG. 3B is a flowchart showing a processing procedure by software. FIG. 3C is a flowchart illustrating a processing procedure based on a combination of hardware and software.

FIG. 4 is a conceptual diagram showing a positional relationship between a line sensor and a subject.

FIG. 5 is a circuit diagram showing a hard logic circuit as a correlating means of the distance measuring apparatus.

FIG. 6 is a block diagram showing a detailed configuration of a distance measuring apparatus according to the present invention.

FIG. 7 is a flowchart illustrating a processing procedure of a correlation operation as the first embodiment of the distance measuring apparatus.

8 (a) and 8 (b) show a comparison of operation areas used in the conventional method and the present invention, FIG. 8 (a) is a conceptual diagram showing an area used in the conventional method, and FIG. FIG. 3 is a conceptual diagram showing an area used in the distance measuring apparatus.

FIG. 9 is a flowchart illustrating a correlation calculation processing procedure according to the second embodiment of the distance measuring apparatus.

FIGS. 10A to 10C show graphs related to a subject and areas for storing errors (correction values) of conventional and present left and right sensors, and FIG. A graph showing a probability of a person, (b) is a conceptual diagram showing an area of a correction coefficient used in a conventional method,
(C) is a conceptual diagram showing an area used in the present distance measuring device.

FIG. 11 is a graph showing the output of each sensor corresponding to FIG. 2 (d).

12 (a) and 12 (b) show the outputs of the right sensor and the left and right sensors as references, FIG. 12 (a) is a graph showing the difference between the outputs of the left and right sensors and (b) FIG. 4 is an explanatory diagram showing a positional relationship between a sensor unit of a right sensor as a reference and a subject.

FIG. 13 is a flowchart illustrating a processing procedure of an interpolation calculation as a third embodiment of the distance measuring apparatus.

FIG. 14 is a flowchart illustrating a correlation calculation processing procedure as another embodiment of the distance measuring apparatus.

FIG. 15 is a diagram showing [Equation 1] showing an output of each left sensor portion when light having a shift amount with respect to the right sensor is incident on the left sensor.

FIG. 16 is a diagram showing [Equation 2] based on a difference between left and right sensors.

FIG. 17 is a diagram showing [Equation 3] obtained by further expanding and expressing the above [Equation 2].

FIG. 18 is a diagram illustrating a minimum value Fmi obtained by an interpolation operation;
The figure which shows [Equation 4] showing the relationship between n and SIFT amount.

[Explanation of symbols]

1a, 1b: lens (for sensor), 2a, 2b: line sensor, 3a, 3b: signal output waveform, 4: A / D converter, 5: arithmetic unit (correlation means), 6: subject, 7: output unit Reference numeral 8 shutter, 9 EEPROM, 10 control means (CPU), 12 feeding means, 13 zoom lens, 14 calculation register, 15 RAM, 16 ROM, 17 calculation means, 18 register ( 19) port. S1 to S16: processing steps of the first and second embodiments of the present invention; S1 to S40: processing steps of the third embodiment of the present invention; S51 to S61: processing steps of other embodiments of the present invention; S104: arithmetic processing step by hardware; S105 to S108: arithmetic processing step by software; S109 to S113: arithmetic processing step by hardware and software.

Claims (3)

[Claims] 1. A light receiving means for receiving a subject image by a pair of light receiving element rows having parallax and outputting a pair of subject image signal rows, and receiving the output of the light receiving means to receive the pair of subject image signal rows. A correlation means for outputting a correlation value of the first portion of the first and second light-receiving element arrays; Data input means for selectively inputting only partial data of a second part narrower than the first part, and interpolation means for performing a predetermined interpolation operation based on the input data. Characteristic ranging device. 2. A light receiving means for receiving a subject image by a pair of light receiving element rows having parallax and outputting a pair of subject image signal rows, wherein the pair of subject image signal rows has a first number of pixels. Means for dividing into a plurality of blocks; correlation means for receiving an output of the light receiving means and outputting a correlation value of the pair of subject image signal strings; Means for resetting the number of pixels to a second number of pixels smaller than the number of pixels, and all of the object image signal rows of one of the pair of light receiving element rows and the subject image signal of the other light receiving element row Data input means for selectively inputting only the data of the second number of pixels in a column; and interpolating means for performing a predetermined interpolation operation based on the input data. Distance measuring device. 3. Two line sensors that output two light pattern signals according to a luminance distribution of a subject image observed from different visual fields having parallax; and comparing the two light pattern signals to generate a parallax of the subject image. Pitch difference calculating means for calculating a relative position difference based on the pitch of the line sensors in units of an array pitch, based on an output result of the pitch difference calculating means, selecting an output signal of the line sensor, and based on the result, Calculation control means for calculating the relative position difference between the two light patterns with a precision finer than the sensor pitch, wherein the pitch difference calculation means is constituted by a hard logic circuit, and the calculation control means is a microcomputer and A distance measuring device comprising software.