JP3064064B2 - Distance measuring device for passive autofocus system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a passive type auto-focusing device which receives light from a subject, measures the distance to the subject, and adjusts the focus based on the measurement result so that the taking lens is focused. 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 a photographing distance of a camera or the like, adjusts a photographing lens based on a result of the distance measurement, and adjusts a focus. You can enjoy shooting more easily. Various types of this autofocusing device have been developed, and the main one is a distance measuring method by triangulation. As a method based on the triangulation method, there is a passive type in which a light receiving sensor provided in a camera receives light from a subject to measure a shooting distance.

[0003] Among passive distance measuring devices of this kind, two are known.
Some light receiving sensors are provided. In the distance measuring device including the two light receiving sensors, from the measurement result in the case where two objects are present, the existence of the object can be considered in two ways. There is a possibility that the image will be shifted.

For this reason, the present applicant has already proposed a distance measuring mechanism comprising three light receiving element arrays so that a clear image can be obtained by performing a reliable distance measurement (Japanese Patent Laid-Open No. 3-4).
2642). The principle of distance measurement by this distance measuring mechanism will be described with reference to FIGS. The distance measuring mechanism is 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 light-receiving element arrays 1b, 2b, 3b, so that a subject image passes through the imaging lenses 1a, 2a, 3a and forms an image on the light-receiving element arrays 1b, 2b, 3b. FIG. 19 shows a case where one subject P exists. Then, the displacement amount of the output signal P ₀ relating to the luminance distribution of the subject P detected by the light receiving element array 1b serving as a reference from the optical axis T ₀ of the reference light receiving sensor 1 is detected by x ₀ , and the first light receiving element array 2b The amount of displacement 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 3 b The amount of displacement 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 phase differences 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 ,
Each interval B of T _2, the imaging lens 1a, 2a, 3a and a light receiving element array 1b, 2b, 3b of the interval A between the light receiving surface, an imaging lens
1a, 2a, the distance to the object P Lp, and the distance from the optical axis T ₀ to the subject P and X, the principle of triangulation from 3a,

X = x ₀ * Lp / A Further, 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

X ₂ = {(B + X) / Lp} * A By substituting Equation 1 into each of Equations 2 and 3,

X ₁ = − {(B / Lp) * A} + x ₀

X ₂ = (B / Lp) * A + x ₀

[0005] Comparing Equation 4 and Equation 5, x ₁ , x ₂
Are based on x ₀ , respectively.

## EQU6 ## It can be seen that there is a shift by (B / Lp) * A = Xp. Therefore, by obtaining this Xp,

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

An operation for obtaining the above Xp will be described with reference to FIG. (A) is a comparison of output signals relating to the luminance distribution of the subject images of the light receiving element arrays 1b, 2b, 3b that have received light from the two subjects P, Q, with reference output signals P ₀ , Q _0. 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 coincide with each other as shown in FIG. 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 shifted by the same distance, and the waveforms of the three signals match. The waveforms of these three signals become information on the same subject P. Next, as shown in (C), if the output signals Q ₁ and Q ₂ are shifted until they match the output signal Q ₀ , the shift amount becomes Xq.

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

[0008]

However, when the above-described conventional distance measuring operation is performed in accordance with 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, a correlation between the output signal of the reference light receiving element row 1b and the output signal of the second light receiving element row 3b is calculated, and the reference light receiving element row 1b, the first light receiving element row 2b, and the second
Since the coincidence of the waveforms of the light receiving element row 3b will be detected,
The number of correlation operations increases and the signal processing time increases. For this reason, the time required for the distance measurement becomes long, and when the subject is dynamic, the image is taken out of focus, and the image may be unclear.

Further, when mounting the light receiving sensors 1, 2, and 3 to the distance measuring device, there is a possibility that a mounting error occurs in each device, and the optical system for distance measuring is shifted.
That is, as shown in FIG. 18, when the normal position where the imaging lens 1a of the light receiving sensor 1 is attached is indicated by a solid line,
Since deviates the optical axis T ₀ of the image forming lens 1a when mounted deviate from the normal position as indicated by a broken line, shifted the imaging position on the light receiving element array 1b. Alternatively, in the case where the imaging lens 1a is mounted at a regular position, even if the mounting position of the light receiving element row 1b is shifted,
The imaging position on the light receiving element row 1b is shifted. For this reason,
While 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 mounted, the subject distance is erroneously measured unless the processing is performed using the output signal in the range d when the light receiving element array 1b is mounted with a deviation. There is a risk of doing it. In addition, since the mounting errors of the imaging lenses 1a differ depending on each distance measuring device, it is not possible to uniformly correct all the distance measuring devices.

Therefore, the present invention has a light receiving sensor which has three light receiving sensors, can perform signal processing in a short time, can obtain a clear image as much as possible, and captures the brightness of the subject. It is an object of the present invention to provide a distance measuring device that correctly processes an output signal of a light receiving sensor and prevents erroneous distance measurement as much as possible even if an error occurs in mounting.

[0011]

In order to achieve the above objects, a distance measuring apparatus for a passive type autofocus apparatus according to the present invention comprises three sets of light receiving sensors for capturing a luminance distribution of a subject,
A second difference calculating circuit for calculating a second difference between the output signals of the respective light receiving sensors, a zero cross detecting circuit for detecting a zero cross point of the output signal of each of the second difference calculating circuits, and the respective zero cross detecting circuits A zero cross memory circuit that stores the zero cross behavior signal obtained by the above, and a match detection circuit that compares the zero cross behavior signals stored in the respective zero cross memory circuits and detects a match between them. Adjusting means for adjusting the position of the pixel of the line sensor corresponding to the output signal to start writing to the zero cross memory circuit by an external operation, and the adjusting means adjusts the position of the pixel to the zero cross memory circuit according to each light receiving sensor. Adjust the writing start position and set one of the three With reference to the zero-crossing behavior signal obtained from the reference light-receiving sensor, the zero-crossing behavior signals obtained from the other two light-receiving sensors are sequentially slid, and the coincidence of these zero-crossing behavior signals is detected by the coincidence detection circuit. Then, the distance to the subject is calculated from the slide amount.

[0012]

The output voltage corresponding to the object luminance distribution is obtained by the light receiving element array constituting the light receiving sensor, and the secondary difference distribution of the output voltage behaves at the zero level. The zero-cross point of this behavior becomes equal to the luminance distribution of the same part of the subject in a state where the three light receiving sensors are appropriately shifted from a predetermined reference part.

The amount of deviation can be obtained as a sliding amount by detecting the signal waveform of the zero-crossing behavior by sliding in the coincidence detecting circuit.

From this slide amount, the distance to the subject can be calculated by triangulation.

When the light receiving sensor is deviated from a proper position when the light receiving sensor is attached to the distance measuring device, the position at which the output signal of the light receiving sensor is written into the zero-cross memory circuit with respect to the amount of the deviation. Is adjusted by the above-mentioned adjusting means, accurate distance measurement data can be obtained in the same manner as in the state where the camera is properly mounted.

[0016]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a distance measuring apparatus for an automatic focusing apparatus according to the present invention. FIGS. 1 to 11 show the first embodiment, FIGS. 12 to 16 show the second embodiment, and FIG. 17 shows the third embodiment.

The first embodiment will be described with reference to FIGS.

Each of the light receiving sensors 10, 20, 30 is constituted by combining a line sensor composed of a light receiving element array in which an appropriate number of pixels are juxtaposed, and an imaging lens, and as shown in FIG. Is provided with three imaging lenses 10a, 20a and 30a, and light emitted from a subject is
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 with respect to the optical axis 10c of the central sensor 10. It is in. In addition, the line sensor 10
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, drive signals from the sensor drivers 11, 21, and 31 are separately input to the line sensors 10b, 20b, and 30b, and the line sensors 10b, 20b, and 30b receive the drive signals from the respective drive signals. The capture of light from the subject is started based on the information. The sensor drivers 11, 21, and 31 are connected to the control circuit 40 by a drive control signal line 40a.
Is controlled by a drive control signal output from the controller.

On the other hand, as shown in FIG. 1, the output terminals of the line sensors 10b, 20b, and 30b are connected to secondary difference calculation circuits 12, 22, and 32, respectively.
The respective line sensors 10b, 20b, by 12, 22, 32,
The secondary difference of the luminance distribution signal of the object obtained in 30b is calculated. As shown in FIG. 3, these secondary difference calculation circuits 12, 22, and 32 convert the output signals Vin of the respective pixels of the line sensors 10b, 20b, and 30b into sample-and-hold circuits 12a, 12b, and 12b.
Samples and holds sequentially while shifting by c, 12d, 12e, and the operational amplifier 12f

[Mathematical formula-see original document] Vout = (R2 / (2 * R1)) * (Vin (n-2) -2 * Vin (n-1) + Vin (n)) is calculated to obtain a secondary difference. FIG. 4 shows a time chart of the secondary difference calculation circuits 12, 22, and 32. Also, as shown in FIG. 7, the subject luminance has a distribution waveform shown in FIG. 7A, and its primary difference waveform and secondary difference waveform are shown in FIGS. 7B and 7C, respectively. .

As shown in FIG. 1, the output signals of the secondary difference calculation circuits 12, 22, and 32 are respectively zero-cross detection circuits.
13, 23, and 33, and the second-order difference calculation circuits 12, 2
The zero-cross point of the secondary difference obtained in steps 2 and 32 is detected.
As shown in FIG. 5, the zero-cross detection circuit 13 (23, 3
3) The second difference calculation circuit 1 is connected to the input terminal of the comparator 13a.
2 (22, 32) output signal Vin is input, and the reference terminal is grounded. The output side of the comparator 13a is connected to flip-flops 13b and 13c, 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 AND circuit 13e, and the output signals of the AND circuits 13d and 13e are input to the OR circuit 13f. Then, as shown in the timing chart of FIG.
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 synchronized 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 above-mentioned 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 crossing behavior is
Address operation circuit 1 corresponding to pixel positions b, 20b, 30b
It is stored in correspondence with the addresses output from 5, 25 and 35. In addition, these address operation circuits 15, 25, and 35 are connected to an adjustment control signal line from adjustment means (not shown) which is externally operated.
A deviation adjustment signal is input via 15a, 25a, and 35a. This deviation adjustment signal is obtained by measuring the distance of a subject at a known distance to obtain a correction amount caused by an error in mounting the light receiving sensors 10, 20, and 30, and corresponding to the correction amount, the data of the zero cross point is converted to the zero cross point data. Memory circuits 14, 2
These signals are for setting the positions of the pixels of the line sensors 10b, 20b, and 30b corresponding to the output signals for starting writing to the lines 4 and 34. Now, these correction amounts are stored in the central memory circuit.
14, 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 operation circuits 15, 25, and 35, and the address signal is sequentially incremented.

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

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

## EQU11 ## In accordance with ADDRESS = COUNTER1-Ladj, it is stored at each address according to each pixel. Note that S in Equations 9 and 10 is a constant. If the adjustment range is A, 0 <Cadj, Radj, Ladj <A
-1.

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

The zero cross memory circuits 14, 2
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,
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, a data memory signal is output from the control circuit 40 to the data memory circuit 80, and address data and distance data are stored in the data memory circuit 80 based on the signal.

Next, referring to FIGS. 8 and 9, the procedure of writing and reading the luminance information of the subject in the memory will be described.

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 to the zero cross memory circuits 14, 24, 34 (step 805). Note that zero-cross detection is performed between step 804 and step 805. Next, proceeding to step 806, it is determined whether reading has been completed for all pixels based on the value of the first counter 50. If not, proceeding to step 807, the first counter 50 is counted up. Returning to 804, one-pixel reading and writing to the zero-cross memory circuits 14, 24, 34 are performed (step 805). And zero-cross memory circuits 14, 2
When data is written to 4, 34, the first counter 50
Address operation circuits 15, 25, 35 based on the count signal of
The address is specified and stored in memory. At this time, the addresses to be stored are specified in accordance with the above-mentioned equations (9), (10) and (11). If the address is negative, no writing is performed.

If reading of all pixels is completed and the determination in step 806 is YES, the flow advances 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 the data in the central zero cross memory circuit 14, the right zero cross memory circuit 24, and the left zero cross memory circuit 34 match. A judgment is made (step 903). If the data match, proceed to step 904, where the first counter
The numerical value of the count signal (COUNTER1) of 50 is used as address data, and the counter signal (CO
UNTER2) is written to 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, where the first counter determines whether reading of the memory data (reference data) corresponding to all valid pixels of the central line sensor 10b is completed.
Judge based on the value of 50, if not completed step
Proceeding to 906, the first counter 50 is counted up, and then returns to step 902 to execute steps up to step 905.

When the reading of the reference data is completed, the process proceeds from step 905 to step 907, where the data of the right and left zero-cross memory circuits 24 and 34 are shifted by a specified amount with respect to the data of the central zero-cross memory circuit 14. It is determined based on the value of the second counter 60 whether or not steps 901 to 905 have been executed (shift reading) (step 907). If the shift reading has not been completed, the second counter 60 is counted up and the step
Returning to step 901, steps 902 to 905 are repeated.
If the shift readout is completed, step 90
Go to 9.

The reading of the memory data from step 901 to step 908 is performed by the address operation circuit 15,
According to Equations (9), (10) and (11), from the central zero-cross memory circuit 14,

ADDRESS = COUNTER1 From the right side zero cross memory circuit 24,

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

ADDRESS = COUNTER1 + SC
It is read according to OUTER2. The relationship between the write address and the read address at this time will be described with reference to FIG.
Note that the write address is given by the above formulas 9, 10 and 11
The correction is performed in accordance with the equations, and the correction amounts Cadj, Radj, Ladj have already been obtained.
Shall be included.

FIG. 10A shows the case where the count signal of the second counter 60 is 0 (COUNTER2 = 0). At this time, the first counter 50 is incremented from 0 to (W-1) (step 906). , Line sensors 10b, 20b, 3
The data stored at the address corresponding to each pixel of 0b is compared to detect a match between 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 shifted from S to (S + W-1).
Incremented to Next, the second counter 60 is incremented (step 908), and while the counter signal of the second counter 60 is 1 (COUNTER2 = 1), the first counter 50 is incremented from 0 to (W-1) (step 908). 906), line sensor 10b, 20
The data stored in the addresses corresponding to the pixels b and 30b are compared to detect a match between the data. Therefore, when COUNTER2 = 1, the address is from 0 to (W-1) for the center line sensor 10b, from 1 to W for the right line sensor 20b, and (for the left line sensor 30b. S-1) to (S + W)
-2) is incremented. In other words, the memory data of the right-side zero-cross memory circuit 24 and the memory data of the left-side zero-cross memory circuit 34 are shifted from the memory data of the central zero-cross memory circuit 14 one pixel at a time to perform coincidence detection.

Then, while the second counter 60 is incremented (step 908), the coincidence detection is repeated until the count signal of the second counter 60 becomes COUNTER2 = S. FIG. 11A shows COUNTER = S−
1 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 No. 34 coincides with the zero-cross point is equal to the shift amount X in the equation (6).
corresponds to p. Then, this deviation amount is stored in the data memory circuit 80 as distance data in step 904.

If it is determined in step 907 that the predetermined shift reading has been completed, the flow advances to step 909. In step 904, the distance data written in the data memory circuit 80 is output to a photographic lens driving device (not shown). The lens moves to a predetermined position to focus on the subject.

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

In the second embodiment, the light receiving sensors 10, 20,
Numeral 30 denotes a combination of one line sensor composed of a light receiving element array in which an appropriate number of pixels are juxtaposed, and three imaging lenses. As shown in FIG. Image lenses 10a, 20a, and 30a are provided, and light emitted from the subject passes through these image forming lenses 10a, 20a, and 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, each of which has a line sensor central part 10b,
The line sensor right portion 20b and the line sensor left portion 30b are provided. These light receiving sensors 10, 20, and 30 are a central sensor 10, a right sensor 20, and a left sensor 30, respectively.
Optical axes 20c and 30c of the right sensor 20 and the left sensor 30, respectively.
Are located symmetrically about the optical axis 10c of the central sensor 10.

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

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

The output signal of the secondary difference calculation circuit 12 is
As shown in FIG. 12, a zero-cross point of the secondary difference that is input to the zero-cross detection circuit 13 and obtained by the secondary difference calculation circuit 12 is detected. This zero-cross detection circuit 13
This is the same as that of the embodiment shown in FIG.

The signal waveform of the zero cross behavior obtained by the zero cross detection circuit 13 is
The part corresponding to b, the part corresponding to the line sensor right part 20b, and the part corresponding to the line sensor left part 30b are divided and respectively input to the zero cross memory circuits 14, 24, and stored. At this time, the zero-cross behavior is stored in the central 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 35 via adjustment control signal lines 15a, 25a, and 35a from adjustment means (not shown) that is operated from the outside. This deviation adjustment signal is obtained by measuring the distance of a subject at a known distance to obtain a correction amount caused by an error in mounting the light receiving sensors 10, 20, and 30, and corresponding to the correction amount, the data of the zero cross point is converted to the zero cross point data. 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. Now, assuming that these correction amounts are Cadj for the value for the central memory circuit 14, Radj for the value for the right memory circuit 24, and Ladj for the value for the left memory circuit 34, the address arithmetic circuits 15, 25, 35 First
When the count signal (COUNTER1) of the counter 50 is input and sequentially incremented, the central memory circuit 14
Then

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

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

## EQU17 ## In accordance with ADDRESS = COUNTER1-Ladj, the data is stored at each address according to each pixel. If the adjustment range is A, 0 <Cadj, Radj,
Ladj <A-1.

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

The zero cross memory circuits 14, 2
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,
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, a data memory signal is output from the control circuit 40 to the data memory circuit 80, and address data and distance data are stored in the data memory circuit 80 based on the signal.

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

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

Since the line sensor 8 is composed of one line, it is first determined whether or not the reading of the first pixel of the portion related to the line sensor left portion 30b has been started based on the value of the read pixel number counter (step S1). 1404),
The output is performed one pixel at a time until reading of the first part is started (step 1405). When the reading of the first part is started, the first counter 50 is reset (step 1406). Then, data corresponding to one pixel of the line sensor left portion 30b is read out (step 140).
7) Read the data to the left zero cross memory circuit 3
4 is written (step 1408). Note that zero-cross detection is performed between step 1407 and step 1408. Next, the process proceeds to step 1409, where it is determined whether reading has been completed for all pixels based on the value of the first counter 50. If not, the process proceeds to step 1410, where the first counter 50 is counted up. 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 operation circuit based on the count signal of counter 50
Address is specified from 35 and stored. At this time,
The address to be stored is specified according to the above equation (17). If the address is negative, no writing is performed.

When the reading of all the pixels of the left portion 30b of the line sensor is completed and the result of step 1409 is YES, step 15
Proceeding to 03 (FIG. 15), it is determined whether reading of the first pixel of the portion related to the line sensor central portion 10b has been started based on the value of the read pixel counter, and 1 is maintained until the reading of the first portion is started. It is output pixel by pixel (step 1504). If the reading of the first part is started, the first counter 50 is reset (step 150).
5) Similarly to the above steps 1407 to 1410, for the line sensor central portion 10b, while performing the zero-cross detection, reading is performed pixel by pixel (step 1506) and writing to the central portion zero-cross memory 14 (step 1507). 1
The judgment of the completion of the reading for all the pixels of the line sensor central portion 10b based on the value of the counter 50 (step 1508) is performed while counting up the first counter 50 (step 150).
9) repeated. Note that the address to be memorized is
Specified according to equation 5. If the address is negative, no writing is performed.

When reading of all the pixels in the line sensor central portion 10b is completed and YES is determined in the step 1508, the process proceeds to a step 1603 (FIG. 16) to output one pixel at a time (step 1604). Right part 20b
The start of reading of 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 line sensor central part 10b, the line sensor right part 20b is read out one pixel at a time (step 1606) and written to the right zero cross memory 24 (step 1607) while the zero cross detection is being performed. The judgment of the completion of reading of all the pixels of the line sensor right portion 20b based on the value of the counter 50 (step 1608) is performed while counting up the first counter 50 (step 160).
9) repeated. When data is written to the right-side zero cross memory circuit 24, the data is stored in the address specified by the address arithmetic circuit 25 in accordance with Expression 16 based on the count signal of the first counter 50. If the address is negative, no writing is performed.

If reading of all the pixels of the line sensor 8 is completed and the determination in the step 1608 is YES,
As in 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. 24, it is determined whether or not the data of the left zero cross memory circuit 34 matches. Then, when the shift reading is completed,
Distance measurement data is output from the data memory circuit 80 (step 909).

In the procedure for detecting the coincidence of the memory data of the zero-cross memory circuits 14, 24, and 34, the first counter 50 and the address arithmetic circuits 15, 25, and 35 calculate
Equations (12) and (17) of the first embodiment correspond to equations (16) and (17).
Similarly to Equations 13 and 14, the central zero-cross memory circuit 14
From

ADDRESS = COUNTER1 From the right side zero cross memory circuit 24,

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

ADDRESS = COUNTER1 + SC
It is read according to OUTER2. Note that S in 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 in accordance with the above equations (15), (16) and (17). Assume that the quantities Cadj, Radj, Ladj are included.

According to the second embodiment, since one line sensor is used and divided into three, the line sensor is used.
The secondary difference calculation circuit and the zero-cross detection circuit are also each one set. For this reason, the distance measuring apparatus shown in the first embodiment using three line sensors has a structure in which three sets of secondary difference calculation circuits and zero-cross detection circuits are provided corresponding to each line sensor. However, in the distance measuring apparatus according to the second embodiment, one line sensor, one set of a secondary difference calculation circuit, and a zero-cross detection circuit are sufficient, and the number of components 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 denoted 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 parts, and the line sensor central part 10b, the line sensor right part 20b, and the line sensor left part 30b, respectively. There is. Then, the output signal of the line sensor 8 is input to the secondary difference calculation circuit 12, the secondary difference is calculated by Expression 8, and the secondary difference output is input to the zero cross detection circuit 13.

The signal waveform of the zero-crossing behavior obtained by the zero-crossing detection circuit 13 is
The part corresponding to b, the part corresponding to the line sensor right part 20b, and the part corresponding to the line sensor left part 30b are divided and respectively input to the zero cross memory circuits 14, 24, and stored. 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 address output from the address calculation circuits 25 and 35 corresponding to the pixel position, and in the line sensor central part 10b. It is stored according to the count signal (COUNTER1) of the counter 50. That is, the first address arithmetic circuits 25 and 35
The count signal (COUNTER1) of the counter 50 is input, and the count signal (COUNT) is supplied to the central memory circuit 14.
While TER1) is input and incremented sequentially,
In the central memory circuit 14,

ADDRESS = COUNTER1 In the right memory circuit 24,

ADDRESS = COUNTER1 In the left memory circuit 34,

## EQU23 ## In accordance with ADDRESS = COUNTER1, it is stored at each address according to each pixel.

The count signals (COUNTER2) of the second counter 60 are input to the address arithmetic circuits 25 and 35, and the second counter 60 and the first counter 50 are controlled 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. Further, address processing information is input from the control circuit 40 to the address calculation circuits 25 and 35, and based on the address processing information, a predetermined write signal and readout are performed from the address calculation circuits 25 and 35 to the zero-cross memory circuits 24 and 34. And a signal are output.

Then, the zero cross memory circuits 14, 2
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,
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, a data memory signal is output from the control circuit 40 to the data memory circuit 80, and address data and distance data are stored in the data memory circuit 80 based on the signal.

Further, the control circuit 40 is provided with adjustment control signal lines 40b, 4
A deviation adjustment signal is input via 0c and 40d. This deviation adjustment signal is obtained by measuring the distance of a subject at a known distance to obtain a correction amount caused by an error in mounting the light receiving sensors 10, 20, and 30, and corresponding to the correction amount, the data of the zero cross point is converted to the zero cross point data. Line sensor 10 corresponding to an output signal to start writing to memory circuits 14, 24, 34
b, 20b, and 30b are signals for setting the positions of the pixels, and whether the reading of the first pixel of the portion related to the line sensor left portion 30b, the line sensor central portion 10b, and the line sensor right portion 20b has been started is performed. An offset is given to the value determined by the read pixel 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 luminance information of the subject in the memory is the same as that in the second embodiment. In order to correct the mounting error of the light receiving sensors 10, 20, and 30, the zero cross memory circuit 14 is used. , 24, and 34 are executed in a state where they are offset in advance. Therefore, in the state where the write has already been offset, the count signal (COUN) of the first counter 50 is supplied to the address arithmetic 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.

ADDRESS = COUNTER1 In the right memory circuit 24,

ADDRESS = COUNTER1 In the left memory circuit 34,

## EQU26 ## In accordance with ADDRESS = COUNTER1, it is stored at each address according to each pixel. The reading of the memory data is performed by the first counter 50.
And the address arithmetic circuits 25 and 35, from the central zero cross memory circuit 14,

ADDRESS = COUNTER1 From the right side zero cross memory circuit 24,

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

ADDRESS = COUNTER1 + SC
It is read according to OUTER2. Note that S in Expression 29 is a constant. The relationship between the write address and the read address at this time is the same as in the case of FIGS.

[0060]

As described above, according to the distance measuring apparatus for the passive type auto-focusing apparatus according to the present invention, the brightness of the subject is captured by the three line sensors, and 2
The next difference is calculated, the zero cross point of the secondary difference is used as a feature point, the zero cross data is stored, and the other two zero cross data are sequentially shifted by one pixel using one of the three as the reference zero cross data. The two data are compared to determine whether they match with respect to the zero-cross point, and the distance to the subject is calculated using the amount of shift when they match as distance data. The calculation processing speed increases. Therefore, it is possible to reliably capture a dynamic subject and perform quick focusing.

Furthermore, since the position of the pixel of the line sensor corresponding to the output signal for starting the writing of the data of the zero cross point into the zero cross memory circuit can be adjusted by an external operation, the light receiving sensor can be used in this distance measuring device. Even when a mounting error occurs during mounting, the luminance information of the subject can be reliably processed, and erroneous distance measurement can be prevented as much as possible.

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

[Brief description of the drawings]

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

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

FIG. 3 is a diagram illustrating a calculation of a secondary difference from an output of a line sensor.
It is a circuit diagram of a next difference calculation circuit.

FIG. 4 is a time chart in the circuit of FIG. 3;

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

FIG. 6 is a time chart in the circuit of FIG. 5;

FIG. 7 is a diagram showing a subject luminance distribution and primary and secondary differences therefrom.

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

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

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

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

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

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

FIG. 14 is a flowchart illustrating a procedure for writing data obtained from a line sensor into a zero-cross memory circuit according to a second embodiment, and relates to a left portion of the line sensor.

FIG. 15 is a flowchart illustrating a procedure for writing data obtained from a line sensor into a zero cross memory circuit according to a second embodiment, and relates to a central portion of the line sensor.

FIG. 16 is a flowchart according to a second embodiment illustrating a procedure for writing data obtained from the line sensor into the zero cross memory circuit, and relates to a right portion of the line sensor.

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

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

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

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

[Explanation of symbols]

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

Claims (1)

(57) [Claims] 1. A light receiving sensor for capturing a luminance distribution of a subject, a secondary difference calculating circuit for calculating a secondary difference between output signals of the respective light receiving sensors,
A zero-cross detection circuit that detects a zero-cross point of the output signal of the next difference calculation circuit; a zero-cross memory circuit that stores a zero-cross behavior signal obtained by each of the zero-cross detection circuits; A match detection circuit for comparing the behavior signals to detect these matches, and externally operating the position of the pixel of the line sensor corresponding to the output signal for starting the writing of the zero-cross point data to the zero-cross memory circuit Adjustment means for adjusting by
The write start position in the zero-cross memory circuit is adjusted by the adjusting means according to each light receiving sensor, and a zero-crossing behavior signal obtained from the reference light receiving sensor based on one of the three sets of light receiving sensors is used as a reference. On the other hand, the zero-crossing behavior signals obtained from the other two light receiving sensors are sequentially slid, the coincidence of these zero-crossing behavior signals is detected by the coincidence detection circuit, and the distance to the subject is calculated from the sliding amount. Characteristic distance measuring device for passive autofocus device.