JPH05107061A - Range finder for passive type auto-focusing apparatus - Google Patents

Abstract

PURPOSE:To prevent false measurement of a distance due to a fitting error and to enable quick and accurate measurement of the distance by adjusting a position of start of writing to a zero cross memory in accordance with each photosensor and by detecting two other amounts of slide in relation to a zero cross behavior signal being a reference. CONSTITUTION:After secondary differences of luminance distribution signals of the light from a subject which is caught by line sensors 10b, 20b and 30b are computed 12, 22 and 32, the respective zero cross points thereof are detected 13, 23 and 33 and waveform signals thereof are stored in zero cross memory circuits 14, 24 and 34 corresponding to addresses outputted from address computing circuits 15, 25 and 35 corresponding to positions of pixels. Since a deviation adjusting signal for setting the positions of pixels corresponding to the amount of correction generated according to a fitting error is inputted to the circuits 15, 25 and 35, false measurement of a distance due to the fitting error is prevented. Besides, the amounts of slide at the time when one zero cross point is used as reference zero cross data and two other ones are made to accord therewith are used as distance data, and the distance to the subject is determined.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive autofocus device that receives light from an object, measures the distance to the object, and adjusts the focus so that the taking lens is focused based on the measurement result. The present invention relates to a distance measuring device for measuring a distance to a subject.

[0002]

2. Description of the Related Art An autofocus device is a device that automatically measures the shooting distance of a camera or the like and adjusts the shooting lens based on the distance measurement result to focus. Now you can enjoy shooting more easily. Various types of this autofocus device have been developed, but the main one is a distance measuring method by a triangulation method. One of the triangulation methods is a passive type in which a light-receiving sensor provided in a camera receives light from a subject and measures a shooting distance.

Two of the passive type distance measuring devices of this type are
There is one in which one light receiving sensor is arranged. In the distance measuring device composed of these two light receiving sensors, there are two possible modes of existence of the subject from the measurement results when two subjects are present, and reliable distance measurement cannot be performed and the focus cannot be achieved. The image may be shifted.

For this reason, the applicant of the present application has already proposed a distance measuring mechanism consisting of three light receiving element arrays so that a clear image can be obtained by performing reliable distance measurement (Japanese Patent Laid-Open No. 3-4.
No. 2642). The principle of distance measurement by this distance measuring mechanism will be described based on FIGS. 19 and 20. The distance measuring mechanism includes the reference light receiving sensor 1 and the first
It comprises a light receiving sensor 2 and a second light receiving sensor 3, and these light receiving sensors 1, 2 and 3 are imaging lenses 1a, 2a and 3a, respectively.
And the light receiving element rows 1b, 2b, 3b, and the subject image is formed on the light receiving element rows 1b, 2b, 3b through the imaging lenses 1a, 2a, 3a. Further, FIG. 19 shows a case where one subject P exists. Then, the displacement amount of the output signal P ₀ related to the luminance distribution of the subject P detected by the reference light receiving element array 1b from the optical axis T ₀ of the reference light receiving sensor x ₀ is detected by the first light receiving element array 2b. The displacement amount of the output signal P ₁ related to the brightness distribution of the subject P from the optical axis T ₁ of the first light receiving sensor 2 is x ₁ , and the output signal related to the brightness distribution of the subject P detected by the second light receiving element array 3b. The displacement amount of P ₂ from the optical axis T ₂ of the second light receiving sensor 3 is x ₂ . These displacement amounts x ₀ , x ₁ , x ₂ represent the phase difference regarding the luminance distribution of the subject image detected by the light receiving element arrays 1b, 2b, 3b. Then, the optical axes T ₀ , T ₁ ,
The distance between T ₂ is B, the distance between the imaging lenses 1a, 2a and 3a and the light receiving surfaces of the light receiving element rows 1b, 2b and 3b is A, and the imaging lens is
Assuming that the distance from 1a, 2a, 3a to the subject P is Lp, and the distance from the optical axis T ₀ to the subject P is X, the principle of triangulation

## EQU1 ## X = x ₀ * Lp / A. In addition, including the sign of the direction in which the image of the output signal appears with reference to the optical axis T ₀ ,

[Number 2] _{-x 1 = {(B-X} ) / Lp} * A

## EQU3 ## x ₂ = {(B + X) / Lp} * A. By substituting the equation 1 into each of the equation 2 and the equation 3,

## EQU4 ## x ₁ =-{(B / Lp) * A} + x ₀

## EQU5 ## x ₂ = (B / Lp) * A + x ₀ .

Comparing equation 4 and equation 5, x ₁ and x ₂
Are based on x ₀ respectively,

## EQU6 ## It can be seen that (B / Lp) * A = Xp. Therefore, by finding this Xp,

## EQU7 ## Lp = A * B / Xp can be calculated.

The operation for obtaining Xp will be described with reference to FIG. (A) is a comparison of the output signal relating to the luminance distribution of the subject images of the light receiving element rows 1b, 2b, 3b that received the light from the two subjects P, Q with the reference output signals P ₀ , Q _0. , (A) to (b), if the waveforms of the output signals P ₁ and P ₂ are shifted until the output signals P ₀ , P ₁ and P ₂ match, the shift amount becomes Xp. Become. That is, since the shift amounts of P ₁ and P ₂ are equal at this time, when the output signals of the light receiving element array 2b and the output signal of the light receiving element array 3b are offset by the same distance, the waveforms of the three signals match. The waveforms of these three signals are information about the same subject P. Next, as shown in (C), if the output signals Q ₁ and Q ₂ are shifted to a state where they match the output signal Q ₀ , the shift amount becomes Xq.

The above Xp and Xq obtained as described above
From the above equation 7 to the distances Lp to the subjects P and Q,
Lq will be required.

[0008]

However, when the above-described conventional distance measuring operation is executed according to the principle, the correlation between the output signal of the reference light receiving element array 1b and the output signal of the first light receiving element array 2b is calculated, Next, the correlation between the output signal of the reference light receiving element array 1b and the output signal of the second light receiving element array 3b is calculated, and the reference light receiving element array 1b, the first light receiving element array 2b, and the second light receiving element array 2b are calculated.
Since the matching of the waveforms of the light receiving element array 3b will be detected,
The number of correlation calculations increases and the signal processing time increases. Therefore, the time required for distance measurement becomes long, and when the subject is dynamic, the image may be out of focus and the image may be unclear.

Further, when the light receiving sensors 1, 2 and 3 are attached to the distance measuring device, a mounting error may occur in each device, and the distance measuring optical system may be displaced.
That is, as shown in FIG. 18, when the regular position where the imaging lens 1a of the light receiving sensor 1 is attached is shown by a solid line,
When it is attached so as to be deviated from the normal position as shown by the broken line, the optical axis T ₀ of the imaging lens 1a is displaced, so that the imaging position on the light receiving element array 1b is displaced. Alternatively, even if the imaging lens 1a is mounted at a regular position and the mounting position of the light receiving element array 1b is displaced,
The image forming position on the light receiving element array 1b is displaced. For this reason,
The output signal in the range D of the light-receiving element array 1b is processed when the light-receiving element array 1b is properly attached, whereas the object distance is erroneously measured unless the output signal in the range d is processed when the light-receiving element array 1b is attached in a displaced manner. There is a risk of doing it. Moreover, the mounting error of these imaging lenses 1a differs depending on the individual distance measuring devices, so that it is impossible to uniformly correct all the distance measuring devices.

In view of this, the present invention has three light receiving sensors so that signal processing can be performed in a short time and a clear image can be obtained as much as possible, and at the same time, a light receiving sensor for capturing the brightness of an object is provided. An object of the present invention is to provide a distance measuring device in which an output signal of a light receiving sensor is correctly processed even if an error occurs in mounting to prevent erroneous distance measurement as much as possible.

[0011]

For the above-mentioned purpose, a passive autofocus apparatus distance measuring apparatus according to the present invention comprises three sets of light receiving sensors for capturing the luminance distribution of an object,
A second-order difference calculation circuit that calculates a second-order difference of the output signals of the respective light-receiving sensors, a zero-cross detection circuit that detects a zero-cross point of the output signals of the respective second-order difference calculation circuits, and the respective zero-cross detection circuits. The zero-cross memory circuit for storing the zero-cross behavior signal obtained by, and a match detection circuit for comparing these zero-cross behavior signals stored in the respective zero-cross memory circuit to detect these matches, the data of the zero-cross point The adjusting means for adjusting the position of the pixel of the line sensor corresponding to the output signal for starting the writing to the zero cross memory circuit by external operation is provided, and the adjusting means adjusts to the zero cross memory circuit according to each light receiving sensor. Adjust the writing start position and set one of the above three photosensors. The zero-cross behavior signal obtained from the other two light-receiving sensors is sequentially slid with respect to the zero-cross behavior signal obtained from the reference light-receiving sensor, and the coincidence detection circuit detects the coincidence of these zero-cross behavior signals. The distance from the slide amount to the subject is calculated.

[0012]

The output voltage according to the subject brightness distribution is obtained by the light receiving element array forming the above light receiving sensor, and the secondary difference distribution of the output voltage behaves at the zero level. The zero-cross points of this behavior are equal to the luminance distribution regarding the same portion of the subject in a state where the three light receiving sensors are appropriately deviated from the predetermined reference portions.

This amount of deviation can be obtained as the amount of sliding by detecting the signal waveform of the zero-cross behavior by sliding the signal waveform with the coincidence detecting circuit.

The distance to the subject can be calculated from this slide amount by the triangulation method.

When the light receiving sensor is attached to the distance measuring device and is deviated from the normal position, the write start position of the output signal of the light receiving sensor to the zero cross memory circuit with respect to this deviation amount. Is adjusted by the adjusting means, the accurate distance measurement data can be obtained in the same manner as in the state in which it is properly attached.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The distance measuring device for an autofocus device according to the present invention will be specifically described below with reference to the illustrated embodiments. 1 to 11 show the first embodiment, FIGS. 12 to 16 show the second embodiment, and FIG. 17 shows the third embodiment.

A first embodiment will be described with reference to FIGS.

The light receiving sensors 10, 20 and 30 are constructed by combining a line sensor consisting of a light receiving element array in which an appropriate number of pixels are arranged in parallel and an image forming lens, and as shown in FIG. Is provided with three image forming lenses 10a, 20a, 30a, and the light emitted from the subject is formed by these image forming lenses 10a, 20a, 30a.
Line sensor that is placed behind the a, 20a, 30a
Images are formed on 10b, 20b, and 30b. These light receiving sensors 10, 20,
Reference numerals 30 denote a central sensor 10, a right sensor 20, and a left sensor 30, respectively.The optical axes 20c and 30c of the right sensor 20 and the left sensor 30 are symmetrical positions with respect to the optical axis 10c of the central sensor 10. It is in. In addition, the line sensor 10
Reference numerals b, 20b and 30b are a central line sensor 10b, a right line sensor 20b and a left line sensor 30b, respectively.

As shown in FIG. 1, the line sensors 10b, 20b and 30b are respectively supplied with drive signals from the sensor drivers 11, 21 and 31, and the line sensors 10b, 20b and 30b are supplied with the drive signals. Based on this, the capture of light from the subject is started. Further, these sensor drivers 11, 21, 31 are connected to the control circuit 40 by a drive control signal line 40a,
It is controlled by the drive control signal output from.

On the other hand, to the output terminals of the line sensors 10b, 20b, 30b, as shown in FIG. 1, quadratic difference calculation circuits 12, 22, 32 are connected, respectively, and the quadratic difference calculation circuits are connected.
12, 22, 32 by the respective line sensor 10b, 20b,
The second-order difference of the luminance distribution signal of the subject obtained in 30b is calculated. As shown in FIG. 3, the second-order difference calculation circuits 12, 22, 32 convert the output signals Vin of the pixels of the line sensors 10b, 20b, 30b into sample-hold circuits 12a, 12b, 12 respectively.
While sequentially shifting by c, 12d, 12e, sample and hold, and by op amp 12f via a resistor of appropriate value,

## EQU00008 ## The second order difference is obtained by calculating Vout = (R2 / (2 * R1)) * (Vin (n-2) -2 * Vin (n-1) + Vin (n)). A time chart in the second-order difference calculation circuits 12, 22, 32 is shown in FIG. Further, as shown in FIG. 7, the subject brightness has the distribution waveform shown in FIG. 7A, and its primary difference waveform and secondary difference waveform are shown in FIGS. 7B and 7C, respectively. ..

The output signals of the second-order difference calculation circuits 12, 22, 32 are, as shown in FIG.
It is input to 13, 23, 33, and the second-order difference calculation circuit 12, 2
The zero-cross point of the secondary difference obtained in 2 and 32 is detected.
As shown in FIG. 5, the zero cross detection circuit 13 (23, 3
The second order difference calculation circuit 1 is connected to the input terminal of the comparator 13a in 3).
The output signal Vin of 2 (22, 32) is input, and the reference terminal is grounded. Flip-flops 13b and 13c are connected to the output side of the comparator 13a, and the Q output of the flip-flop 13b and the inverted Q output of the flip-flop 13c are ANDed.
The inverted Q output of the flip-flop 13b and the Q output of the flip-flop 13c are input to the circuit 13d, and the output signals of the AND circuits 13d and 13e are input to the OR circuit 13f. Then, as shown in the time chart of FIG. 6, the output signal V of the secondary difference calculation circuit 12
When in is input in synchronization with the pulse φ1 and the output signal Vin crosses the zero level and the sign is changed, the zero-cross signal is the ZERO pulse in synchronization with the clock pulse φ2 of the flip-flops 13b and 13c. Is output as.

The signal waveforms of the zero-cross behavior obtained by the zero-cross detection circuits 13, 23 and 33 are input to and stored in the zero-cross memory circuits 14, 24 and 34, respectively.
At this time, the zero-cross behavior is determined by each line sensor 10.
Address operation circuit 1 corresponding to pixel positions b, 20b, and 30b
It is stored in correspondence with the address output from 5, 25, 35. In addition, these address operation circuits 15, 25, 35 are provided with adjustment control signal lines from adjustment means (not shown) operated from the outside.
The deviation adjustment signal is input via 15a, 25a, and 35a. This deviation adjustment signal measures the distance to a subject at a known distance to obtain the correction amount caused by the mounting error of the light receiving sensors 10, 20, 30. Memory circuit 14, 2
This is a signal for setting the position of the pixel of the line sensor 10b, 20b, 30b corresponding to the output signal for starting writing in 4, 34. Now, these correction amounts are set in the central memory circuit.
The value for 14 is Cadj, the value for the right memory circuit 24 is Radj, and the value for the left memory circuit 34 is Ladj.
Then, the count signal (COUNTER1) of the first counter 50 is input to the address calculation circuits 15, 25, and 35, and the central memory circuit 14

## EQU00009 ## ADDRESS = COUNTER1-Cadj-S In the right memory circuit 24,

## EQU10 ## ADDRESS = COUNTER1-Radj-S In the left memory circuit 34,

## EQU10 ## According to ADDRESS = COUNTER1-Ladj, the data is stored in each address according to each pixel. Note that S in the equations 9 and 10 is a constant. If the adjustment range is A, then 0 <Cadj, Radj, Ladj <A
-1.

Further, the count signal (COUNTER2) of the second counter 60 is inputted to the address arithmetic circuits 25 and 35, and the second counter 60 and the first counter 50 are based on the output signal of the control circuit 40. Counting up and resetting. The second counter 60 increments the address when data is read from the zero-cross memory circuits 24 and 34, as will be described later. In addition, the address calculation circuits 15, 25 and 35 have control circuits 40
Address processing information is input from the address calculation circuit, and predetermined write signals and read signals are output from the address operation circuits 15, 25 and 35 to the zero-cross memory circuits 14, 24 and 34 based on the address processing information.

Then, the zero cross memory circuits 14 and 2 are
A match detection circuit 70 is connected to the output side of 4, 34,
The output side of the coincidence detection circuit 70 is connected to the control circuit 40.

Further, the count signal of the first counter 50 is input to the address port 81 of the data memory circuit 80 and
The count signal of the counter 60 is input to the distance data port 82 of the data memory circuit 80. Further, the count signals of the first counter 50 and the second counter 60 are both input to the control circuit 40. Further, the control circuit 40 outputs a data memory signal to the data memory circuit 80, and the address data and the distance data are stored in the data memory circuit 80 based on the signal.

Next, the procedure of writing and reading the brightness information of the subject in the memory will be described with reference to FIGS.

When the distance measurement is started, the line sensors 10b, 20
Electric charges are accumulated in b and 30b (step 801), the second counter 60 is reset (step 802), and the first counter 50 is reset (step 803). And
Data corresponding to one pixel of each line sensor 10b, 20b, 30b is read (step 804), and the read data is written in the zero-cross memory circuits 14, 24, 34 (step 805). Note that the zero-cross detection is executed between step 804 and step 805. Next, in step 806, it is determined whether or not reading has been completed for all pixels based on the value of the first counter 50. If not read, the process proceeds to step 807 to count up the first counter 50 and then to step Returning to 804, one-pixel reading and writing to the zero-cross memory circuits 14, 24 and 34 are performed (step 805). And the zero-cross memory circuit 14, 2
When data is written to 4 and 34, the first counter 50
Address operation circuit 15, 25, 35 based on the count signal of
It is memorized by specifying the address from. At this time, the address to be memorized is designated according to the equations (9), (10) and (11). If the address is negative, no writing is done.

When the reading of all the pixels is completed and the determination in step 806 is YES, the process proceeds to step 901 (FIG. 9) to reset the first counter 50. And
The memory is read from the zero-cross memory circuits 14, 24, 34 (step 902), and the match detection circuit 70 determines whether or not the data in the central zero-cross memory circuit 14, the right-side zero-cross memory circuit 24, and the left-side zero-cross memory circuit 34 match. Judge (step 903). If the data match, the process proceeds to step 904, and the first counter at that time
Using the numerical value of the count signal (COUNTER1) of 50 as the address data, the counter signal (CO
The value of UNTER2) is written in the data memory circuit 80 as distance data. The judgment in step 903 is N
If it is O, the process proceeds to step 905, and a first counter is used to determine whether or not the reading of the memory data (reference data) corresponding to all the effective pixels of the central line sensor 10b is completed.
Judging by the value of 50, if not completed, step
After proceeding to 906 and counting up the first counter 50, the process returns to step 902 and steps up to step 905 are executed.

When the reading of the reference data is completed, the routine proceeds from step 905 to step 907, in which the data of the right and left zero cross memory circuits 24, 34 are shifted by a specified amount with respect to the data of the central zero cross memory circuit 14. Whether or not the steps 901 to 905 have been executed (shift reading) is determined by the value of the second counter 60 (step 907). When the shift reading is not completed, the second counter 60 is counted up and the step is performed.
Return to 901 and repeat steps 902 to 905.
When the shift reading is completed, step 90
Go to 9.

Reading of memory data from step 901 to step 908 is performed by the address calculation circuit 15,
25 and 35 correspond to the equations (9), (10), and (11), and from the central zero cross memory circuit 14,

[Equation 12] ADDRESS = COUNTER1 From the right side zero cross memory circuit 24,

[Expression 13] ADDRESS = COUNTER1 + COUNTER2 From the left zero-cross memory circuit 34,

[Equation 14] ADDRESS = COUNTER1 + S−C
It is read according to OWNER2. The relationship between the write address and the read address at this time will be described with reference to FIG.
In addition, the write address is the above-mentioned equation 9, equation 10, equation 11
The correction amounts Cadj, Radj, Ladj have been performed according to the formula.
Shall be included.

FIG. 10A shows the case where the count signal of the second counter 60 is 0 (COUNTER2 = 0), at which time the first counter 50 is incremented from 0 to (W-1) (step 906). , Line sensors 10b, 20b, 3
The data stored in the addresses corresponding to the respective pixels of 0b are compared to detect the coincidence of the data. Therefore, when COUNTER2 = 0, the addresses of the pixels of the central line sensor 10b and the right line sensor 20b are incremented from 0 to (W-1), and the addresses of the pixels of the left line sensor 30b are incremented from S to (S + W-1).
Is incremented up to. Then, the second counter 60 is incremented (step 908), and while the counter signal of the second counter 60 is set to 1 (COUNTER2 = 1), the first counter 50 is incremented from 0 to (W-1) (step 906), line sensors 10b, 20
The data stored in the addresses corresponding to the pixels b and 30b are compared to detect the coincidence of the data. Therefore, when COUNTER2 = 1, the address is 0 to (W-1) for the central line sensor 10b, 1 to W for the right line sensor 20b, and (for the left line sensor 30b). S-1) to (S + W
-2) is incremented. That is, the memory data of the right-side zero-cross memory circuit 24 and the left-side zero-cross memory circuit 34 are shifted pixel by pixel with respect to the memory data of the central zero-cross memory circuit 14 to perform coincidence detection.

Then, while incrementing the second counter 60 (step 908), the coincidence detection is repeated until the count signal of the second counter 60 becomes COUNTER2 = S. Note that FIG. 11A shows COUNTER = S-
1 is shown, and FIG. 11B shows the case where COUNTER2 = S.

That is, the zero-cross memory circuits 14, 24,
The value of the second counter 60 when the memory data of 34 coincides with each other at the zero-cross point is the deviation amount X in the equation (6).
Corresponds to p. Then, this shift amount is stored as distance data in the data memory circuit 80 in step 904.

If it is determined in step 907 that the predetermined shift reading is completed, the process proceeds to step 909, and the distance data written in the data memory circuit 80 in step 904 is output to a photographic lens driving device (not shown) for photographing. The lens moves to a predetermined position and focuses on the subject.

Next, the second embodiment shown in FIGS. 12 to 16 will be described.

In the second embodiment, the light receiving sensors 10, 20,
Reference numeral 30 denotes a combination of one line sensor consisting of a light receiving element array in which an appropriate number of pixels are arranged in parallel, and three image forming lenses, and as shown in FIG. Image lenses 10a, 20a, 30a are provided, and light emitted from a subject is transmitted through these imaging lenses 10a, 20a, 30a to form an image on a corresponding portion of a line sensor 8 provided behind. .. Therefore, the line sensor 8 is divided into three parts, and the line sensor central portion 10b,
The line sensor right part 20b and the line sensor left part 30b are provided. Further, these light receiving sensors 10, 20, 30 are respectively a central sensor 10, a right sensor 20, and a left sensor 30,
Optical axes 20c and 30c of the right sensor 20 and the left sensor 30, respectively
Are located symmetrically with respect to the optical axis 10c of the central sensor 10.

As shown in FIG. 12, the drive signal from the sensor driver 11 is input to the line sensor 8, and the line sensor 8 starts capturing light from the subject based on the drive signal. Further, the sensor driver 11 is connected to the control circuit 40 by the drive control signal line 40a and is controlled by the drive control signal output from the control circuit 40.

On the other hand, at the output terminal of the line sensor 8,
As shown in FIG. 12, a quadratic difference calculation circuit 12 is connected, and the quadratic difference calculation circuit 12 calculates the quadratic difference of the luminance distribution signal of the subject obtained by the line sensor 8. This quadratic difference calculation circuit 12 is the same as that of FIG. 3 shown in the first embodiment, and the quadratic difference is calculated by the equation (8).

The output signal of the second-order difference calculation circuit 12 is
As shown in FIG. 12, the zero-cross point which is input to the zero-cross detection circuit 13 and which is obtained by the second-order difference calculation circuit 12 is detected. This zero-cross detection circuit 13 has a first
It is similar to that shown in FIG. 5 of the embodiment.

The signal waveform of the zero-cross behavior obtained by the zero-cross detection circuit 13 is the line sensor central portion 10
It is divided into a portion corresponding to b, a portion corresponding to the right portion of the line sensor 20b, and a portion corresponding to the left portion of the line sensor 30b, which are input and stored in the zero cross memory circuits 14, 24, 34 respectively. At this time, the zero-cross behavior is stored in the center portion 10b, the right portion 20b, and the left portion 30b of the line sensor 8 in correspondence with the addresses output from the address calculation circuits 15, 25, and 35. In addition, these address operation circuits 15, 25,
A deviation adjustment signal is input to the reference numeral 35 from an adjustment means (not shown) operated from the outside through the adjustment control signal lines 15a, 25a and 35a. This deviation adjustment signal measures the distance to a subject at a known distance to obtain the correction amount caused by the mounting error of the light receiving sensors 10, 20, 30. This is a signal for setting the position of the pixel of the line sensor 10b, 20b, 30b corresponding to the output signal for starting writing to the memory circuits 14, 24, 34. Assuming that these correction amounts are Cadj for the central memory circuit 14, Radj for the right side memory circuit 24 and Ladj for the left side memory circuit 34, the address arithmetic circuits 15, 25 and 35 have the following values. First
While the count signal (COUNTER1) of the counter 50 is input and incremented sequentially, the central memory circuit 14
Then

[Expression 15] ADDRESS = COUNTER1-Cadj In the right side memory circuit 24,

## EQU16 ## ADDRESS = COUNTER1-Radj In the left side memory circuit 34,

[Equation 17] According to ADDRESS = COUNTER1-Ladj, each address is stored according to each pixel. If the adjustment range is A, then 0 <Cadj, Radj,
Let Ladj <A-1.

Further, the count signal (COUNTER2) of the second counter 60 is inputted to the address arithmetic circuits 25 and 35, and the second counter 60 and the first counter 50 are based on the output signal of the control circuit 40. Counting up and resetting. The second counter 60 increments the address when data is read from the zero-cross memory circuits 24 and 34, as will be described later. Further, address processing information is input to the address arithmetic circuits 25 and 35 from the control circuit 40, and based on the address processing information, a predetermined write signal and read from the address arithmetic circuits 25 and 35 to the zero-cross memory circuits 24 and 34. The signals and are output.

Then, the zero cross memory circuits 14 and 2 are
A match detection circuit 70 is connected to the output side of 4, 34,
The output side of the coincidence detection circuit 70 is connected to the control circuit 40.

The count signal of the first counter 50 is input to the address port 81 of the data memory circuit 80 and
The count signal of the counter 60 is input to the distance data port 82 of the data memory circuit 80. Further, the count signals of the first counter 50 and the second counter 60 are both input to the control circuit 40. Further, the control circuit 40 outputs a data memory signal to the data memory circuit 80, and the address data and the distance data are stored in the data memory circuit 80 based on the signal.

Next, the procedure for writing and reading the brightness information of the subject in the memory will be described with reference to FIGS. 14 to 16.

When the distance measurement is started, electric charges are accumulated in the line sensor 8 (step 1401), the second counter 60 is reset (step 1402), and the readout pixel number counter (not shown) in the control circuit is reset (step 1402). Step 140
3).

Since the line sensor 8 is composed of one line, first, it is judged from the value of the read pixel number counter whether or not the reading of the first pixel of the portion related to the line sensor left portion 30b has been started (step 1404),
The pixels are output pixel by pixel until the reading of the first portion is started (step 1405). When the reading of the first portion is started, the first counter 50 is reset (step 1406). Then, the data corresponding to one pixel in the left portion 30b of the line sensor is read (step 140
7) Read the read data to the left zero cross memory circuit 3
Write to 4 (step 1408). Note that the zero-cross detection is executed between step 1407 and step 1408. Next, the procedure proceeds to step 1409, and it is determined whether or not the reading has been completed for all pixels based on the value of the first counter 50. If not, the procedure proceeds to step 1410 to count up the first counter 50 and then the step Returning to 1407, one pixel reading and writing to the left zero cross memory circuit 34 are performed (step 1408). When data is written to the left zero-cross memory circuit 34, the first
Address arithmetic circuit based on the count signal of counter 50
It is memorized by specifying an address from 35. At this time,
The address to be memorized is designated according to the equation (17). If the address is negative, no writing is done.

When the reading of all the pixels of the left portion 30b of the line sensor is completed and YES is obtained in step 1409, step 15
The process proceeds to 03 (FIG. 15) to determine whether the reading of the first pixel of the portion related to the central portion 10b of the line sensor is started or not by the value of the read pixel number counter, and 1 is read until the reading of the first portion is started. It is output pixel by pixel (step 1504). When the reading of the first portion is started, the first counter 50 is reset (step 150).
5) As in steps 1407 to 1410, with respect to the central portion 10b of the line sensor, while the zero-crossing detection is being performed, reading is performed pixel by pixel (step 1506) and writing to the central portion zero-cross memory 14 (step 1507). 1
The determination of completion of reading of all the pixels in the central portion 10b of the line sensor based on the value of the counter 50 (step 1508) and counting up the first counter 50 (step 150
9) Repeated. The address to be memorized is the number 1
5 Specified according to formula. If the address is negative, no writing is done.

When the reading of all the pixels of the central portion 10b of the line sensor is completed and YES is determined in step 1508, the process proceeds to step 1603 (FIG. 16), outputting one pixel at a time (step 1604). Right part 20b
The start of reading the first pixel of the portion related to is determined by the value of the read pixel number counter, and if the reading of the first portion is started, the first counter 50 is reset (step 1605). And the line sensor left part 30b
Similarly to the procedure for the central portion 10b of the line sensor and the right portion 20b of the line sensor, while the zero-cross detection is being performed, reading is performed pixel by pixel (step 1606) and writing to the right-side zero-cross memory 24 (step 1607), first. The determination of the completion of reading of all the pixels of the right portion 20b of the line sensor according to the value of the counter 50 (step 1608) and counting up the first counter 50 (step 160
9) Repeated. When data is written in the right-side zero-cross memory circuit 24, it is stored in the address designated by the address arithmetic circuit 25 according to the equation 16 based on the count signal of the first counter 50. If the address is negative, no writing is done.

If the reading of all the pixels of the line sensor 8 is completed and the determination in step 1608 is YES,
Similar to the procedure from step 901 to step 909 shown in FIG. 9, the memory data is read from the zero cross memory circuits 14, 24 and 34, and the coincidence detection circuit 70 reads the central zero cross memory circuit 14 and the right zero cross memory circuit. 24. It is determined whether or not the data of the left zero cross memory circuit 34 match. Then, when the shift reading is completed,
Distance measurement data is output from the data memory circuit 80 (step 909).

In the procedure of detecting the coincidence of the memory data of the zero-cross memory circuits 14, 24, 34, the first counter 50 and the address operation circuits 15, 25, 35 are used to calculate
Corresponding to equation 16 and equation 17, equation 12 and number of the first embodiment
As in formulas 13 and 14, the central zero-cross memory circuit 14
From

[Expression 18] ADDRESS = COUNTER1 From the right side zero cross memory circuit 24,

ADDRESS = COUNTER1 + COUNTER2 From the left zero-cross memory circuit 34,

[Equation 20] ADDRESS = COUNTER1 + S−C
It is read according to OWNER2. Note that S in the equation (20) is a constant. The relationship between the write address and the read address at this time is the same as in FIGS. 10 and 11 of the first embodiment, and the write address is performed according to the above equations (15), (16) and (17) and has already been corrected. It is assumed that the quantities Cadj, Radj, Ladj are included.

According to the second embodiment, one line sensor is used, and this line sensor is divided into three and used.
The second-order difference calculation circuit and the zero-cross detection circuit are also provided in pairs. For this reason, in the distance measuring device using the three line sensors according to the first embodiment, three pairs of the second-order difference calculation circuit and the zero-cross detection circuit are provided for each line sensor. However, in the distance measuring apparatus according to the second embodiment, one line sensor, one set of second-order difference calculation circuit, and zero-cross detection circuit are sufficient, and the number of parts can be reduced.

Next, a third embodiment shown in FIG. 17 will be described. The same parts as those in the first or second embodiment are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, as in the second embodiment, one line sensor 8 is divided into three, and the line sensor central portion 10b, the line sensor right portion 20b, and the line sensor left portion 30b are respectively divided. There is. The output signal of the line sensor 8 is input to the secondary difference calculation circuit 12, the secondary difference is calculated by the equation (8), and the secondary difference output is input to the zero-cross detection circuit 13.

The signal waveform of the zero-cross behavior obtained by the zero-cross detection circuit 13 is the line sensor central portion 10
It is divided into a portion corresponding to b, a portion corresponding to the right portion of the line sensor 20b, and a portion corresponding to the left portion of the line sensor 30b, which are input and stored in the zero cross memory circuits 14, 24, 34 respectively. At this time, the zero-crossing behavior is stored in the right part 20b and the left part 30b of the line sensor 8 in correspondence with the addresses output from the address operation circuits 25 and 35 in correspondence with the pixel position, and in the line sensor central part 10b, the first crossing behavior is stored. It is stored according to the count signal (COUNTER1) of the counter 50. That is, the address arithmetic circuits 25 and 35 have the first
The count signal (COUNTER1) of the counter 50 is input, and the count signal (COUNT
TER1) is input and increments sequentially,
In the central memory circuit 14,

[Expression 21] ADDRESS = COUNTER1 In the right side memory circuit 24,

[Equation 22] ADDRESS = COUNTER1 In the left side memory circuit 34,

[Equation 23] According to ADDRESS = COUNTER1, it is stored in each address according to each pixel.

Further, the count signal (COUNTER2) of the second counter 60 is inputted to the address arithmetic circuits 25 and 35, and the second counter 60 and the first counter 50 are based on the output signal of the control circuit 40. Counting up and resetting. The second counter 60 increments the address when reading data from the zero-cross memory circuits 24 and 34. Further, address processing information is input to the address arithmetic circuits 25 and 35 from the control circuit 40, and based on the address processing information, a predetermined write signal and read from the address arithmetic circuits 25 and 35 to the zero-cross memory circuits 24 and 34. The signals and are output.

Then, the zero-cross memory circuits 14 and 2 are
A match detection circuit 70 is connected to the output side of 4, 34,
The output side of the coincidence detection circuit 70 is connected to the control circuit 40.

The count signal of the first counter 50 is input to the address port 81 of the data memory circuit 80, and
The count signal of the counter 60 is input to the distance data port 82 of the data memory circuit 80. Further, the count signals of the first counter 50 and the second counter 60 are both input to the control circuit 40. Further, the control circuit 40 outputs a data memory signal to the data memory circuit 80, and the address data and the distance data are stored in the data memory circuit 80 based on the signal.

Further, in the control circuit 40, adjustment control signal lines 40b, 4b from the adjusting means (not shown) operated from the outside are supplied.
Deviation adjustment signal is input via 0c and 40d. This deviation adjustment signal measures the distance to a subject at a known distance to obtain the correction amount caused by the mounting error of the light receiving sensors 10, 20, 30. The line sensor 10 corresponding to the output signal that starts writing to the memory circuits 14, 24 and 34
It is a signal for setting the position of the pixel of b, 20b, 30b, and whether or not the reading of the first pixel of the part related to the line sensor left part 30b, the line sensor central part 10b, and the line sensor right part 20b is started. An offset is given to the value determined by the read pixel number counter, writing is started from the read pixel position offset in advance, and the zero cross memory circuit 14 and the address arithmetic circuits 25 and 35 are driven by the count signal (COUNTER1).

The procedure for writing and reading the brightness information of the object in and from the memory is the same as in the second embodiment, and the zero cross memory circuit 14 is used to correct the mounting error of the light receiving sensors 10, 20, 30. , 24, 34 are executed in a pre-offset state. Therefore, with the writing already offset, the count signal (COUNT) of the first counter 50 is sent to the address operation circuits 25 and 35.
TER1) is input, the count signal (COUNTER1) is input to the central memory circuit 14, and the central memory circuit 14 increments sequentially.

[Equation 24] ADDRESS = COUNTER1 In the right side memory circuit 24,

[Expression 25] ADDRESS = COUNTER1 In the left side memory circuit 34,

[Equation 26] According to ADDRESS = COUNTER1, it is stored in each address according to each pixel. Moreover, the reading of the memory data is performed by the first counter 50.
And address arithmetic circuits 25 and 35 from the central zero-cross memory circuit 14,

[Equation 27] ADDRESS = COUNTER1 From the right side zero cross memory circuit 24,

[Equation 28] ADDRESS = COUNTER1 + COUNTER2 From the left zero-cross memory circuit 34,

[Equation 29] ADDRESS = COUNTER1 + S−C
It is read according to OWNER2. Note that S in the equation (29) is a constant. Further, the relationship between the write address and the read address at this time is the same as in the cases of FIGS. 10 and 11.

[0060]

As described above, according to the distance measuring apparatus for the passive type autofocus device according to the present invention, the brightness of the subject is captured by the three line sensors, and the data of 2 is obtained from the data.
The next difference is calculated, the zero-cross data of the second-order difference is used as a feature point and the zero-cross data is stored, and one of the three zero-cross data is used as the reference zero-cross data, and the other two zero-cross data are sequentially shifted by one pixel. Compares whether or not two data match at the zero-cross point, and calculates the distance to the subject using the shift amount at the time of matching as the distance data. The processing speed becomes faster. Therefore, it is possible to reliably capture a dynamic subject and perform quick focusing.

Moreover, since the position of the pixel of the line sensor corresponding to the output signal for starting the writing of the zero-cross point data in the zero-cross memory circuit can be adjusted by an external operation, the light-receiving sensor can be used in this range finder. Even if an attachment error occurs during attachment, the brightness information of the subject can be reliably calculated and erroneous distance measurement can be prevented as much as possible.

In addition, since the zero-cross data of the second-order difference is compared, the distance data can be obtained with high accuracy because it does not depend on the pattern of the subject brightness distribution on the line sensor.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a first embodiment of a distance measuring device for a passive autofocus device.

FIG. 2 is a side view showing a schematic structure of the light receiving sensor of the first embodiment.

FIG. 3 is a diagram for calculating a secondary difference from the output of the line sensor 2
It is a circuit diagram of a next difference calculation circuit.

FIG. 4 is a time chart in the circuit of FIG.

FIG. 5 is a circuit diagram of a zero-cross detection circuit that detects a zero-cross point from a second-order difference signal obtained by a second-order difference calculation circuit.

FIG. 6 is a time chart in the circuit of FIG.

FIG. 7 is a diagram showing a subject brightness distribution and first-order differences and second-order differences corresponding thereto.

FIG. 8 is a flowchart according to a first embodiment showing a procedure for writing data obtained from a line sensor into a zero cross memory circuit.

FIG. 9 is a flowchart according to the first embodiment showing a procedure of reading out predetermined data from the zero-cross memory circuit in order to detect the coincidence of the data stored in the zero-cross memory circuit.

FIG. 10 is a diagram illustrating an operation procedure for reading and comparing data stored in the zero-cross memory circuit according to the first embodiment.

FIG. 11 is a diagram illustrating an operation procedure for reading and comparing data stored in the zero-cross memory circuit according to the first embodiment.

FIG. 12 is a circuit block diagram of a second embodiment of the distance measuring device for the passive type autofocus device.

FIG. 13 is a side view showing a schematic structure of a light receiving sensor of a second embodiment.

FIG. 14 is a flowchart showing a procedure for writing data obtained from the line sensor in the zero-cross memory circuit according to the second embodiment, which relates to the left part of the line sensor.

FIG. 15 is a flowchart showing a procedure of writing data obtained from the line sensor in the zero-cross memory circuit according to the second embodiment, which relates to the central portion of the line sensor.

FIG. 16 is a flowchart according to the second embodiment showing the procedure for writing the data obtained from the line sensor to the zero-cross memory circuit, which relates to the right part of the line sensor.

FIG. 17 is a circuit block diagram of a third embodiment of the distance measuring device for the passive autofocus device.

FIG. 18 is a diagram for explaining a mounting error of the light receiving sensor.

FIG. 19 is an optical path diagram showing the principle of distance measurement.

FIG. 20 is a diagram for explaining the measurement procedure based on the principle of distance measurement, and is a signal diagram relating to the luminance distribution of the subject image detected by the light receiving element array.

[Explanation of symbols]

 10 Light receiving sensor 20 Light receiving sensor 30 Light receiving sensor 10a Image forming lens 20a Image forming lens 30a Image forming lens 10b Central line sensor 20b Right line sensor 30b Left line sensor 11, 21, 31 Sensor driver 12, 22, 32 Second-order difference calculation Circuits 13, 23, 33 Zero-cross detection circuits 14, 24, 34 Zero-cross memory circuits 15, 25, 35 Address operation circuits 15a, 25a, 35a Adjustment control signal line 40 Control circuits 40b, 40c, 40d Adjustment control signal line 50 1st counter 60 Second counter 70 Match detection circuit 80 Data memory circuit

Claims (1)

[Claims] 1. A set of three light receiving sensors for capturing a luminance distribution of an object, a second order difference calculation circuit for calculating a second order difference between output signals of the respective light receiving sensors, and each of the above two sets.
Zero-cross detection circuit for detecting the zero-cross point of the output signal of the next difference calculation circuit, zero-cross memory circuit for storing the zero-cross behavior signal obtained by the respective zero-cross detection circuit, and zero-cross stored in the respective zero-cross memory circuit It consists of a coincidence detection circuit that compares behavior signals and detects these coincidences, and externally operates the position of the pixel of the line sensor corresponding to the output signal that starts writing the data of the zero cross point to the zero cross memory circuit. Adjusting means to adjust by
The write start position to the zero-cross memory circuit is adjusted by the adjusting means according to each light-receiving sensor, and one of the three light-receiving sensors is used as a reference, and the zero-cross behavior signal obtained from the reference light-receiving sensor is used. On the other hand, the zero-cross behavior signals obtained from the other two light-receiving sensors are sequentially slid to detect the coincidence of these zero-cross behavior signals by the coincidence detection circuit, and the distance from the slide amount to the subject is calculated. A distance measuring device for the passive autofocus device that features.