JPH06324257A - Passive type distance measuring instrument for autofocusing device - Google Patents

Abstract

PURPOSE:To perform distance measurement in a wide luminance range by comparing the integrated value of the stored charges of a light receiving means for monitoring with plural reference values in order from a smaller one, completing the storage of charge when it reaches the maximum reference value in a prescribed time or the reference value first after the prescribed time and amplifying the image signal of a line sensor with an amplification factor corresponding to a reference value at the time of completing the storage from among plural amplification factors, in a distance measuring instrument using a charge storing type line sensor. CONSTITUTION:In a driving control circuit 11a, a driving signal is inputted to a line sensor(LS) 8, a signal for selecting one of plural reference values in order from a smaller one to a generating circuit 11d, a signal for selecting one of plural amplification factors in order from a larger one to an amplifier circuit 11c, the reference value is sent from the generating circuit 11d to a detecting circuit 11e in this order, the reference value is successively made to be larger every time when the integrated value of the output of the light receiving means 7 reaches the reference value and the storage in the LS 8 is terminated when it reaches the maximum reference value in a prescribed time or the reference value first after the prescribed time. The reference value is made to comply with the value in the order from a smaller one, the amplification factor is made to comply with a factor in the order from a larger one and the image signal of the LS 8 is amplified with the amplification factor corresponding to a reference value at the time of terminating the storage.

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 the distance measurement method by the triangulation method. There is a passive type that measures the shooting distance by receiving light.

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 including 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).
No. 2642). The principle of distance measurement by this distance measuring mechanism will be described with reference to 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 coupling lenses 1a, 2a, 3a. Further, FIG. 19 shows a case where one subject P exists. 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 1 is detected by the first light receiving element array 2b as x ₀ . 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 , the second light receiving element array 3
The displacement amount of the output signal P ₂ relating to the luminance distribution of the subject P detected by b 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 related to 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 , T
₂ is B, the distance between the imaging lenses 1a, 2a, 3a and the light receiving surfaces of the light receiving element rows 1b, 2b, 3b is A, and the coupling lens 1 is
If the distance from a, 2a, 3a to the subject P is Lp, and the distance from the optical axis T ₀ to the subject P is X, then from 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 ,

## EQU2 ## -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,

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 , P ₂ are shifted until the output signals P ₀ , P ₁ , P ₂ coincide with each other, 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 the 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.

The applicant of the present application has proposed a distance measuring device for a passive autofocus device that utilizes this principle (for example, Japanese Patent Laid-Open No. 42417/1993). This distance measuring device uses a line sensor of a charge storage type as a light receiving sensor, and performs distance measurement by comparing the zero-cross behavior of the second-order difference of the object luminance distribution obtained by this line sensor.

[0009]

However, since the charge storage type line sensor is used, the following problems occur. That is, even if the brightness of the subject is low, if the waiting time is sufficient until the charges are accumulated in the line sensor, the time required for distance measurement becomes long, and the time until shooting becomes long. There is a risk that
Also, when shooting a dynamic subject, the shutter chance is a moment, and if the time required to accumulate the charges becomes long, the captured image will be lost or sufficient distance measurement will be performed. If you do not do so, the image may be out of focus. Therefore, the brightness range of the object for which distance measurement can be performed is narrowed to the extent that the accumulation of charges is completed in a short time.

However, if the brightness range of the subject is narrowed, the range in which photography is possible is narrowed and the versatility of the camera is impaired.

Therefore, according to the present invention, even if the brightness of the object is low, the charge can be accumulated in the line sensor in a short time, and the distance to the object having a wide brightness range can be measured in a short time. It is an object of the present invention to provide a distance measuring device for a passive type autofocus device, which is capable of performing the above.

[0012]

As a technical means for achieving the above object, a distance measuring apparatus for a passive type autofocus device according to the present invention has a line sensor for capturing a luminance distribution of an object. A pair of light receiving sensors, a second-order difference calculation circuit that calculates a second-order difference between the output signals of the light-receiving sensors, a zero-cross detection circuit that detects a zero-cross point of the output signal of the second-order difference calculation circuit, and the zero-cross detection circuit The zero-crossing behavior signals obtained by the above-mentioned three sets of light-receiving sensors are separately stored, and the zero-crossing behavior signals stored in the respective zero-crossing memory circuits are compared to detect a match between them. A zero-crossing behavior signal obtained from the reference light receiving sensor with one of the three light receiving sensors as a reference. On the other hand, a passive method of sequentially shifting the zero-cross behavior signals obtained from the other two light receiving sensors, detecting the coincidence of these zero-cross behavior signals by the coincidence detection circuit, and calculating the distance from the shift amount to the subject. In the range finder for the auto focus device
The light receiving means for monitoring monitors the average brightness of the subject, the integrating circuit for integrating the output of the light receiving means for monitoring, and the detection level for comparing with the integrated value in the integrating circuit. A level detection circuit that outputs a detection signal when the number of times reaches, an amplification circuit that can amplify the image signal output from the line sensor with a plurality of amplification factors having different sizes, And a drive control circuit that drives by selecting an appropriate amplification factor from among the amplification factors, and the detection level of the level detection circuit is prepared in a number equal to the number of the amplification factors with different sizes, The plurality of detection levels are made to correspond in order from the smallest one to the one having the largest amplification factor, and the detection levels are made to correspond to the level detection circuit by the drive control circuit. Each time the detection signal is output from the level detection circuit within a predetermined time, the smallest detection signal is selected and provided in order, and when the detection signal for the maximum detection level is output from the level detection circuit within the predetermined time. The detection signal, or the first detection signal output after the above-mentioned predetermined time has elapsed, causes the line sensor to end the accumulation of electric charges and output an image signal from the line sensor to the detection level at the end of the electric charges accumulation. It is characterized in that the image signal is amplified with a corresponding amplification factor.

In order to reliably drive the single level detection circuit, a reference level for receiving the output signal of the drive control circuit and providing the level detection circuit with a detection level to be used for comparison with the integrated value. The feature is that a generating circuit is provided.

Further, a plurality of level detection circuits are provided, and the drive control circuit monitors the detection signals output from these level detection circuits. In order to avoid switching the detection level in the level detection circuit, the luminance distribution of the subject is eliminated. Three sets of light-receiving sensors having line sensors for capturing light, a second-order difference calculation circuit for calculating a second-order difference of the output signals of the light-reception sensor, and a zero-cross point of the output signal of the second-order difference calculation circuit are detected. A zero-cross detection circuit, a zero-cross behavior signal obtained by the zero-cross detection circuit are separately stored for each of the three light-receiving sensors, and a zero-cross behavior signal stored in each of the zero-cross memory circuits is compared. And a coincidence detection circuit for detecting these coincidences. With respect to the reference, the zero-crossing behavior signals obtained from the other two light-receiving sensors are sequentially shifted with respect to the zero-crossing behavior signals obtained from the reference light-receiving sensor, and the coincidence detection circuit detects the coincidence of these zero-crossing behavior signals. In the range finder for a passive type auto-focus device, which calculates the distance from the shift amount to the subject, the monitor light receiving means for monitoring the average brightness of the subject, and the output of the monitor light receiving means. An integrating circuit for integrating and an integrated value in the integrating circuit are input,
A plurality of level detection circuits having a detection level to be compared with the integrated value and outputting a detection signal when the integrated value reaches the detection level; It is composed of an amplification circuit capable of amplifying an image signal with a plurality of amplification factors having different sizes, and a drive control circuit for driving the amplification circuit by selecting an appropriate amplification factor from the plurality of amplification factors. , The detection levels of the plurality of level detection circuits are made to correspond in order from the smallest to the largest amplification factor, and the drive control circuit outputs the detection signal from the level detection circuit within a predetermined time. The detection signal is selected in ascending order of the detection level, and if the detection signal for the maximum detection level is output from the level detection circuit within the specified time, The detection signal, or the first detection signal output after the elapse of the predetermined time, terminates the charge accumulation in the line sensor and causes the line sensor to output an image signal, which corresponds to the detection level at the end of the charge accumulation. The image signal is amplified at an amplification rate.

[0015]

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

This shift amount can be obtained as a shift amount if the zero crossing behavior is shifted and detected by the coincidence detection circuit.

Then, the distance to the object can be calculated from this shift amount by the triangulation method.

In capturing the luminance distribution of the subject with the line sensor, if the luminance of the subject is high, the integrated value reaches the maximum detection level within the predetermined time or after the predetermined time has elapsed, and the maximum detection is performed. A detection signal corresponding to the level is output from the level detection circuit. Then, the minimum amplification factor is selected by the drive control circuit, the amplification circuit is driven with the minimum amplification factor, and the image signal output from the line sensor is amplified with this minimum amplification factor.

When the brightness of the object is low, the integrated value reaches the minimum detection level after a predetermined time has elapsed, and the corresponding detection signal is output from the level detection circuit. In this case, the drive control circuit selects the maximum amplification factor, the amplification circuit is driven with the maximum amplification factor, and the image signal output from the line sensor is amplified with this maximum amplification factor.

Further, an intermediate amplification factor is selected corresponding to the intermediate detection level. That is, even if the brightness of the subject changes due to the change of the amplification factor, the amplification circuit can output the image signal with substantially the same signal level, and the signals of substantially the same level are used for the detection of the zero-cross behavior. be able to.

[0021]

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.

As shown in FIG. 4, the light receiving sensors 10, 20, 30
Is formed by combining 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 three image forming lenses 10a, 20 are provided on the front surface of the camera.
Lights emitted from the subject are transmitted through these imaging lenses 10a, 20a, 30a and are imaged on the corresponding portions of the line sensor 8 arranged at the rear. Therefore, the line sensor 8 is divided into three parts, which are a line sensor central portion 10b, a line sensor right portion 20b, and a line sensor left portion 30b, respectively. Further, these light receiving sensors 10, 20, 30 are respectively referred to as a central portion sensor 10, a right side sensor 20, and a left side sensor 30, and the optical axes 20c and 30c of the right side sensor 20 and the left side sensor 30 are the central portion sensor 10, respectively.
They are located symmetrically with respect to the optical axis 10c of.

As shown in FIG. 3, a control signal from the line sensor control means 11 is input to the line sensor 8. This line sensor control means 11 is a drive control signal line
It is connected to the control circuit 40 by 40a and controlled by a drive control signal output from the control circuit 40. Further, the line sensor control means 11 includes, as shown in FIG. 1, a drive control circuit 11a, an integration circuit 11b, an amplification circuit 11c, a reference level generation circuit 11d, and a level detection circuit 11e.
The drive control signal from 40 is input to the drive control circuit 11a. The sensor drive signal of the drive control circuit 11a is input to the shift gate unit 8b that switches the operation of the line sensor 8 via the signal line 8a, and the shift gate unit 8b outputs the signal from the subject to the line sensor 8 based on the sensor drive signal. Register 8c of the data related to the brightness of the subject accumulated in the line sensor 8 by opening and closing the capture of the light of the
Transfer to. Further, the amplification factor selection signal and the reference level selection signal output from the drive control circuit 11a are respectively supplied to the amplification factor selection signal line 11f and the reference level selection signal line 11g.
Are input to the amplification circuit 11c and the reference level generation circuit 11d via the. Also, the reference level generation circuit 11d
Is output to the level detection circuit 11e, and the reference level selected by the reference level generation circuit 11d is set as the detection level of the level detection circuit 11e. The detection signal LV of the level detection circuit 11e is input to the drive control circuit 11a via the detection signal line 11h. Also, register 8c
The output signal of is input to the amplifier circuit 11c via the signal line 8d.

The integrating circuit 11b is provided at a position on the front surface of the camera for receiving the light from the subject, and the output of the monitor light receiving means 7 for capturing the average brightness of the subject is output via the monitor signal line 7a. It has been entered. The output of the integrating circuit 11b is sent to the level detecting circuit 11e, and the detection level held in the level detecting circuit 11e is compared with the integrated value of the integrating circuit 11b.

In the reference level generating circuit 11d,
As shown in FIG. 2, a plurality of reference levels S ₁ , S ₂ , S ₃ ,
S ₄ is set, and these reference levels are S ₁ <S ₂
<S ₃ <S ₄ . Then, the drive control circuit 11a
Any _{one of} these reference levels S ₁ , S ₂ , S ₃ , S ₄ is output to the level detection circuit 11e based on the reference level selection signal sent from. Further, a plurality of amplification factors G ₁ , G ₂ , G ₃ and G ₄ are set in the amplification circuit 11c, and these amplification factors are G ₁ > G ₂ > G ₃ > G ₄ and the drive control circuit 11a. The signal output from the line sensor 8 is amplified by any of the amplification factors G ₁ , G ₂ , G ₃ , and G ₄ based on the amplification factor selection signal transmitted from the. Then, the drive control circuit 11a sets the amplification factor G ₁ in the amplification circuit 11c when the reference level S ₁ is selected, and sets the amplification factor G ₂ when the reference level S ₂ is selected. When the level S ₃ is selected, the amplification factor G ₃ is set, and when the reference level S ₄ is selected, the amplification factor G ₄ is set. That is, S ₁ and G ₁ , S ₂ and G ₂ , S ₃ and G ₃ , and S ₄ and G ₄ are selected in combination. In addition, the drive control circuit 11a
Outputs the reference level selection signal in the order of S ₁ , S ₂ , S ₃ , and S ₄ from the smallest reference level, and outputs the detection signal LV related to the maximum reference level S ₄ within the predetermined time t ₀ . If the detection signal LV is output for the first time after the elapse of the predetermined time t ₀ , the drive control circuit 11
a sends the transfer signal SH of the sensor drive signal to the line sensor 8. Upon receipt of this transfer signal SH, the shift gate section 8b opens, the data relating to the brightness of the object captured by the line sensor 8 at that time is transferred to the register 8c, and the data is sent from the register 8c to the amplifier circuit 11c. It

The output of the amplifier circuit 11c is the image signal line 11i.
It is input to the A / D converter 9 via the. In the A / D converter 9, the output signal of the line sensor 8 is digitally converted in synchronization with the clock pulse P1 as shown in FIG. A secondary difference calculation circuit 12 is connected to the output side of the A / D converter 9, and the line sensor 8 is connected by the secondary difference calculation circuit 12.
The second-order difference of the luminance distribution signal of the subject obtained in step 1 is calculated. This second-order difference calculation circuit 12 is
The output signal AD of the D converter 9 is sequentially stored in the storage circuits 12a and 12b by D flip-flops in synchronization with the clock pulse P2,

## EQU00008 ## The secondary difference is obtained by calculating DIFF (n) = AD (n-2) -2 * AD (n-1) + AD (n).

Output signal DIF of the second-order difference calculation circuit 12
As shown in FIG. 3, F is input to the zero-cross detection circuit 13 and detects the zero-cross point of the secondary difference obtained by the secondary difference calculation circuit 12. In the zero cross detection circuit 13,
First, the secondary difference signal DI is calculated by the interpolation calculation circuit shown in FIG.
FF is interpolated. In this interpolation calculation circuit, the secondary difference signal DIFF is stored in the storage circuit 13a by the D flip-flop, and (−1) times and N times of the stored value are obtained,
Input the data multiplied by N to the data select circuit 13b,
(-1) The data obtained by adding the multiplied data and the secondary difference signal DIFF is added to the output data of the data select circuit 13b, and the added data is added to the data select circuit 13b.
Returning to b. That is, in the interpolation calculation circuit, in synchronization with the clock pulse P3,

[Equation 9] NDIFF (m) = N * DIFF (n-1) + m * (DI
FF (n) -DIFF (n-1)) is calculated to linearly approximate the signal DIFF to interpolate the secondary difference signal DIFF. At the same time as this interpolation calculation, whether the sign of the data is positive or negative is output as a sign signal SIGN.

Next, as shown in FIG. 7, the sign output SIGN is input to the D flip-flop 13c of the zero-cross detection circuit 13, and the sign output SIGN and the inverted Q terminal of the D flip-flop 13c are AND circuits. The output signal of the sign output SIGN through the inverter 13e and the Q terminal of the flip-flop 13c are input to the AND circuit 13f.

That is, as shown in the time chart of FIG. 8, the output signal Vin of the line sensor 8 is input to the A / D converter 9 and digitally converted to obtain the output signal AD. When the output signal AD is input to the secondary difference calculation circuit 12, the secondary difference signal DIF is synchronized with the clock pulse P2.
F is obtained, and this signal DIFF is the zero cross detection circuit 13
Input to the first, the signal DIFF is first linearly approximated and interpolated to the signal NDIFF / N and the code signal SIG.
N and are obtained. The code signal SIGN is further synchronized with the clock pulse P3 by the zero-cross detection circuit 13, and the code signal SIGN is set to L from the AND circuit 13d.
The pulse P-ZERO rising when the signal changes from H to H is output as a zero-cross signal, and the pulse N-ZERO rising when the sign signal SIGN changes from H to L is output as a zero-cross signal from the AND circuit 13f. . That is, the pulse P-ZERO is the second-order difference signal DI.
It rises when the zero cross occurs due to the change of the interpolation data NDIFF / N of the FF from positive to negative, and the pulse N
-ZERO is a signal that rises when the interpolation data NDIFF / N changes from negative to positive and crosses zero.

A signal of the zero-crossing behavior obtained by the zero-crossing detection circuit 13 has a portion corresponding to the central portion 10b of the line sensor and a portion corresponding to the right portion 20b of the line sensor,
The line sensor 30b is divided into a portion corresponding to FIG.
Zero cross memory circuit 14,
It is input to and stored in 24 and 34. 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 calculation circuits 25 and 35 according to the pixel position, and in the line sensor central part 10b, the first counter. It is stored according to the 50 count signal (COUNTER1). That is, the count signal (COUNTER1) of the first counter 50 is sent to the address arithmetic circuits 25 and 35.
Is input, and the count signal (C
In the central memory circuit 14,

[Expression 10] ADDRESS = COUNTER1 In the right side memory circuit 24,

[Equation 11] ADDRESS = COUNTER1 In the left side memory circuit 34,

[Equation 12] 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 data is read from the zero-cross memory circuits 24 and 34, as will be described later. Further, the address processing information is input to the address operation circuits 25 and 35 from the control circuit 40, and a predetermined write signal and a read operation are performed from the address operation circuits 25 and 35 to the zero-cross memory circuits 24 and 34 based on the address processing information. The signals and are output.

The zero cross memory circuits 14, 24,
An interpolation position count signal (COUNTER3) is input to the interpolation position count counter 55 from 34, and the interpolation position count counter 55 is counted up and reset based on the output signal of the control circuit 40.
As shown in FIG. 8, the interpolation position counting counter 55 operates in synchronization with a clock pulse P3 having a cycle shorter than the clock pulses P1 and P2, and also in synchronization with the clock pulse P3, a secondary differential signal. The DIFF is divided into four parts, and position codes of 0 to 3 are assigned to the respective divided parts. Then, corresponding to the number of interpolations (4 in this case),
The interpolation position count signal (COUNTER3) of the interpolation position count counter 55 is the zero cross memory circuit 1
Zero cross points detected by the zero cross detection circuit 13 in the zero cross memory circuits 14, 24, 34 corresponding to the above position code in synchronization with the interpolation position count signal (COUNTER3). The position code of is stored.

A coincidence detection circuit 70 is connected to the output side of the zero-cross memory circuits 14, 24 and 34, and the zero-cross behavior signals P-ZERO and N stored in the zero-cross memory circuits 14, 24 and 34 are stored. -ZERO and the position code where the zero cross data is present are sent out. And
The coincidence detection circuit 70 determines whether or not these zero-cross data coincide with the position code. further,
A control circuit 40 is connected to the output side of the coincidence detection circuit 70, and a coincidence signal of zero cross data is sent out.

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, and the interpolation position count signal of the interpolation position counting counter 55 is input to the data memory circuit 80.
The distance data has been entered into port 83. Further, the count signals of the first counter 50, the second counter 60, and the interpolation position counting counter 55 are all 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.

FIG. 9 is a block diagram showing the coincidence detection in the coincidence detection circuit 70, which is a zero-cross memory for subject brightness data output from the line sensor central portion 10b, the line sensor right portion 20b, and the line sensor left portion 30b. The data stored in circuits 14, 24 and 34 are shown as C data, R data and L data, respectively. The L data is input to the D flip-flop 91 and the arithmetic circuit 92, the R data is input to the D flip-flop 93 and the arithmetic circuit 94, and the data latched by the D flip-flop 91 is the arithmetic circuit. The data input to 92 and latched by the D flip-flop 93 is input to the arithmetic circuit 94. Also, the interpolation position counting counter 55
The interpolation position count signal (COUNTER3) is input to the arithmetic circuits 92 and 94, respectively. The outputs of the arithmetic circuits 92 and 94 and the C data are input to the comparison circuit 95, and the data in the case where they are compared by the comparison circuit 95 and coincide with each other are output as coincidence data.

Next, with reference to FIG. 10 to FIG. 14, a procedure of capturing the luminance of the subject by the line sensor 8, writing and reading the luminance information of the subject in the memory, and detecting the coincidence will be described. The first counter 50 and the second counter 60
Operates in synchronization with the clock pulse P2, and the interpolation position counting counter 55 operates in synchronization with the clock pulse P3.

When a release button (not shown) of the camera is depressed, the distance measurement start switch is turned on and the control circuit 40 sends a distance measurement start signal to the drive control circuit 11a of the line sensor control means 11. Upon receiving the distance measurement start signal, the drive control circuit 11a outputs a sensor drive signal to the monitor light receiving means 7 and the line sensor 8, and the monitor light receiving means 7 and the line sensor 8 capture light from the subject. The charge starts to be accumulated (step 1001). Further, a reference level selection signal for selecting the minimum reference level S ₁ is sent from the drive control circuit 11a to the reference level generation circuit 11d, and an amplification factor selection signal for selecting the maximum amplification factor G ₁ is sent to the amplification circuit 11c. At the same time, counting of the predetermined time t ₀ is started.

The output from the monitor light receiving means 7 captured by the monitor light receiving means 7 is input to the integrating circuit 11b according to the brightness of the object, and the integrated value is input to the level detecting circuit 11e. . This level detection circuit 11e includes the minimum reference level S ₁ from the reference level generation circuit 11d.
Is inputted as the detection level, the integrated value is compared with the detection level S _1, and if the integrated value becomes larger than the detection level S ₁ within the predetermined time t ₀ as shown in FIG. The detection signal LV is output from the detection circuit 11e.

The drive control circuit 11a receives the detection signal LV, and the reference level selection signal for selecting the _second smallest reference level S ₂ with respect to the reference level generation circuit 11d is the second largest in the amplifier circuit 11c. Amplification factor selection signals for selecting the amplification factor G ₂ are transmitted, and the counting for the predetermined time t ₀ is continued. Therefore, the level detection circuit 11a compares the detection level S ₂ with the integrated value in the integration circuit 11b. As shown in FIG. 2, when the integrated value becomes larger than the detection level S ₂ within the predetermined time t ₀ , the level detection circuit 11e outputs the detection signal LV.

Further, the drive control circuit 11a receives the detection signal LV, and a reference level selection signal for selecting the second largest reference level S ₃ is supplied to the amplification circuit 11c for the reference level generation circuit 11d. The amplification factor selection signals for selecting a small amplification factor G ₃ are transmitted respectively, and the predetermined time t
The count of ₀ continues. In this state, when the predetermined time t ₀ elapses and the integrated value becomes larger than the detection level S ₃ , as shown in FIG. 2A, the level detection circuit
A detection signal (accumulation completion signal) LV indicating the completion of charge accumulation is output from 11e.

Further, as shown in FIG. 2B, when the integrated value becomes larger than the detection level S ₃ before the elapse of the predetermined time t ₀ , the level detection circuit 11e outputs the detection signal LV to drive control. The circuit 11a receives the detection signal LV, and a reference level selection signal for selecting the maximum reference level S ₄ is supplied to the reference level generation circuit 11d and an amplification factor for selecting the minimum amplification factor G ₄ for the amplification circuit 11c. The selection signals are respectively transmitted, and the counting for the predetermined time t ₀ is continued. When the integrated value becomes larger than the detection level S ₄ regardless of the elapse of the predetermined time t ₀ , the level detection circuit 11e outputs a detection signal (accumulation completion signal) LV indicating completion of charge accumulation.
Is output.

That is, the integrated value of the output of the monitor light receiving means 7 in the integration circuit 11b is compared while shifting from the smaller reference level to the larger reference level in sequence every time the detection signal LV is output within the predetermined time t ₀ . However, when the predetermined time t ₀ has elapsed, the detection signal LV that is output first after the elapse is used as the accumulation completion signal, and when the predetermined time t ₀ has not elapsed, it is output when the maximum reference level S ₄ is exceeded. The accumulated detection signal LV is used as an accumulation completion signal to terminate the accumulation of charges.

When the accumulation completion detection signal LV is output from the level detection circuit 11e, the drive control circuit 11a receives the accumulation completion signal LV and the shift gate section 8b of the line sensor 8 is received.
The transfer signal SH is sent to The transfer signal SH opens the shift gate portion 8b and the line sensor 8
Stops the accumulation of electric charge, and the electric charge accumulated up to that point, that is, the data relating to the luminance of the subject is transferred to the register 8c, and the information relating to the distribution of the subject luminance is sent from the register 8c to the amplifier circuit 11c. The amplifier circuit 11c amplifies the output signal of the line sensor 8 with an amplification factor selected by a command from the drive control circuit 11a. That is, it is amplified by the amplification factors G ₁ , G ₂ , G ₃ , and G ₄ combined with the reference levels S ₁ , S ₂ , S ₃ , and S ₄ selected at the time when the accumulation completion signal LV is output. It As mentioned above, these reference levels and amplification factors are
S ₁ and G ₁ , S ₂ and G ₂ , S ₃ and G ₃ , S ₄ and G ₄ are respectively combined.

In the accumulation of this electric charge in the line sensor 8, when the integration value exceeds the maximum reference level S ₄ and the accumulation completion signal LV is output, it means that the brightness of the object is relatively high, and the minimum reference level. When the accumulation completion signal LV is output exceeding the level S ₁ , it means that the brightness of the subject is relatively low. Then, the minimum gain G ₄ are the maximum reference level S ₄ are combined, since the maximum amplification factor G ₁ is are combined for the minimum reference level S _1, the brightness of the object Even if it changes
The image signal output from the line sensor 8 is amplified by the amplifier circuit 11c.
The signal of almost constant magnitude is output by.

When the accumulation of charges in the line sensor 8 is completed (step 1001), the second counter 60 is reset (step 1002), and the read pixel number counter (not shown) in the control circuit 40 is reset (step 1003).

Since the line sensor 8 is composed of one line, it is first judged by the value of the read pixel number counter whether or not the reading of the first pixel of the part related to the line sensor left part 30b is started (step 1004),
The pixels are output pixel by pixel until the reading of the first portion is started (step 1005). When the reading of the first portion is started, the process proceeds to step 1006, and the first counter 50 is reset.

Next, after proceeding to step 1101 (shown in FIG. 11) and resetting the counter 3, data relating to one pixel of the line sensor left portion 30b of the line sensor 8 is read (step 1102). Then, the processing proceeds to step 1103, the interpolation calculation is executed according to the equation (9), and the interpolation data NDIF
F / N is calculated, and the zero-cross point is detected together with the sign signal SIGN of the interpolation data. At this time, the interpolation calculation is performed based on the interpolation position count signal by counting up the interpolation position counting counter 55, and the count value of the interpolation position counter when the zero-cross point is detected is stored (not shown). ). Next, in step 1104, it is determined whether the interpolation is completed, that is, whether one pixel read in step 1102 is divided into a predetermined number and the interpolation calculation is performed, based on the value of the interpolation position counting counter 55. If it is not completed, the process proceeds to step 1105 to count up the interpolation position counting counter 55 and then returns to step 1103, and steps 1103 and 1104 are repeated until the interpolation is completed. Then, when the division is completed, the process proceeds to step 1106.

In step 1106, the read pixel number counter is counted up, and the process proceeds to step 1107 and step 11
The interpolated position data stored in correspondence with one pixel of the line sensor left portion 30b read out in 02 and interpolated is written in the left zero cross memory circuit 34. Next, the procedure proceeds to step 1108, and it is determined whether the reading is completed for all the pixels included in the left portion 30b of the line sensor by the value of the first counter 50. If not, the procedure proceeds to step 1109. Step after counting up 1 counter 50
Returning to 1101, one pixel reading (step 1102), interpolation calculation, zero cross detection (step 1103), and writing to the left zero cross memory circuit 34 (step 1107) are performed. When data is written in the left zero-cross memory circuit 34, an address is designated by the address calculation circuit 35 based on the count signal of the first counter 50 and the data is stored. At this time, the data to be memorized are the zero-cross position data and the polarity data, and the address to be memorized is designated according to the equation (12).

When the reading of all the pixels of the left portion 30b of the line sensor is completed and YES is obtained in step 1108, step 12
It progresses to 01 (FIG. 12) and it is judged 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 reading pixel number counter, and 1 is read until the reading of the first portion is started. It is output pixel by pixel (step 1202). When the reading of the first portion is started, the first counter 50 is reset (step 120).
3) As in steps 1101 to 1109, the interpolation position count counter 55 is reset (step 1204) for the line sensor central portion 10b, and then one pixel is read (step 1205). Interpolation calculation and zero-cross detection (steps 1207 and 1208) while judging the completion of interpolation based on the signal value.
1206) is executed, and then the read-out pixel number counter is incremented (step 1209), the read-out data of one pixel is written to the central zero-cross memory 14 (step 1210), and the value of the first counter 50 is changed. The determination of the completion of reading of all the pixels of the line sensor central portion 10b (step 1211) is repeated while counting up the first counter 50 (step 1212). The address to be memorized is specified according to the equation (10).

When the reading of all the pixels in the central portion 10b of the line sensor is completed and YES is determined in step 1211, the process proceeds to step 1301 (FIG. 13) to output the pixels one by one (step 1302). Right part 20b
The read start of the first pixel of the portion related to is determined by the value of the read pixel number counter, and if the read of the first portion is started, the first counter 50 is reset (step 1303). And the line sensor left part 30b
In the same manner as for the line sensor central portion 10b and the line sensor right portion 20b, the interpolation position counting counter 55 is reset (step 1204), and then one pixel is read (step 1305). While judging the completion of interpolation by the value of
07, 1308), interpolation calculation and zero-cross detection (step 130
6) is executed, and then the zero-cross detection is performed, the read-out pixel number counter is incremented (step 1309), and the data of one pixel read is written to the right-side zero-cross memory 24 (step 1310), 1
The first is the determination of the completion of reading of all the pixels of the right portion 20b of the line sensor based on the value of the counter 50 (step 1311).
While counting up the counter 50 (step 1312)
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 11 based on the count signal of the first counter 50.

If the reading of all the pixels of the line sensor 8 is completed and the determination in step 1311 is YES,
Proceeding to step 1401 (FIG. 14), the interpolation position counting counter 55 is reset and the first counter 50 is reset (step 1402). And the zero-cross memory circuit 14,
24, 34 from the step 1107 and step 1210, step
The memory data written in 1310 is read (step 1403), and the coincidence detection circuit 70 determines whether or not 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. (Step 1404).

When the number of interpolations is "4", the data conversion operation at the time of matching detection in the matching detection circuit 70 is R
Let r (n) and l (n) be the position data parts of (n) and L (n), respectively, and r (n) + 4-COU for the position data of R (n).
For position data of NTER3 R (n-1), r (n-1) -COUNT
For position data of TER3 L (n), l (n) + COUNT
For position data of ER3 L (n-1), l (n-1) -4 + CO
Regarding position data and polarity data converted by UNTER3, C
It is detected that all the data, R data, and L data match. That is, FIG. 15 is a diagram for explaining the coincidence detection calculation performed by FIG. 9, and as shown in FIG.
With the data for one pixel of C data fixed,
Match detection is performed while incrementing COUNTER3. Now, regarding L data, position data L (n
-1), L (n), and L (n + 1) divided position codes are set to -4 to 7 from the upper bit side, and with respect to R data, position data R (n-2) and R (n-1) ) And R (n) are divided position codes from -4 to 7 from the upper bit side. When the interpolation position counter signal is 0 (COUNTER3 = 0), position codes 0 to 3 for L data, position codes 0 to 3 for L data, and position codes 0 to 3 for R data are used for coincidence comparison. It Then, COUNTER3 is counted up, and when COUNTER3 = 1, position codes 1 to 4 for L data and position codes -1 and 2 for R data are 0 to 3, respectively. It is converted into a position code of 3 and provided for coincidence comparison.
When COUNTER3 = 2, position codes 0 to 3 of C data are compared with position codes 2 to 5 of L data.
In the R data, the position codes -2 to 1 are converted into the position codes 0 to 3 and provided for coincidence comparison. Furthermore, C
When OWNER3 = 3, position codes 0 to 3 of C data are compared with position codes 3 to 6 of L data.
In the data, position codes -3 to 0 are converted into position codes 0 to 3 and provided for coincidence comparison.

If the data match, the process proceeds to step 1405, and the first counter 50 at that time is
Of the count signal (COUNTER1) of the second counter 60 as address data.
The numerical value of NTER2) is used as the upper bit of the distance data, and the interpolation count signal (CO
The numerical value of UNTER3) is written in the data memory circuit 80 as the lower bit of the distance data. If the determination in step 1404 is NO, the process proceeds to step 1406 to determine whether the reading of memory data (reference data) corresponding to all the effective pixels of the central portion 10b of the line sensor 8 is completed. Judging by the value of the counter 50, if it is not completed, proceed to step 1407 to count up the first counter 50 and then return to step 1403 to perform step
Execute up to 1406.

When the reading of the reference data is completed, the process proceeds from step 1406 to step 1408, and whether or not the interpolation is completed by the value of the interpolation position count counter 55, that is, the data of the predetermined number of divided position codes is stored. It is determined whether a match is determined. If the interpolation is not completed, the process proceeds to step 1409 to count up the interpolation position counting counter 55, and then the process returns to step 1402 and the above steps 1402 to 1408 are repeated. If YES is determined in step 1408, the process proceeds to step 1410, and 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, and the above step is performed. 14
It is judged from the value of the second counter 60 whether or not 01 to step 1408 have been executed (shift reading) (step 1410). If the shift read is not completed,
The second counter 60 is counted up, the process returns to step 1401, and steps 1402 to 1410 are repeated. Then, when the shift reading is completed, the process proceeds to step 1412.

The reading of the memory data in steps 1402 to 1411 is performed by the first counter 50 and the address arithmetic circuits 25 and 35 by the equations (10), (11),
Corresponding to equation 12, from the central zero-cross memory circuit 14,

[Expression 13] ADDRESS = COUNTER1-1 From the right side zero cross memory circuit 24,

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

[Expression 15] ADDRESS = COUNTER1 + S-1
-Read according to COUNTER2. Note that S in the equation (15) is a constant. The relationship between the write address and the read address at this time will be described with reference to FIG. It should be noted that if the address is negative, no reading is performed.

FIG. 16A shows when the count signal of the second counter 60 is 0 (COUNTER2 = 0). At this time, the line sensor 8 is incremented while the first counter 50 is incremented from 0 to W (step 1407). 10b, 20b,
The data stored in the addresses corresponding to the respective pixels of 30b are compared to detect the coincidence of those data. Therefore, when COUNTER2 = 0, the address of the pixel of the central portion 10b of the line sensor is incremented from 0 to (W-1), the address of the pixel of the right portion 20b of the line sensor is incremented from 0 to W, and the address of the left portion of the line sensor is increased. In the pixel of 30b, the address is from (S-1) to (S +
W-1) is incremented. Then, for a pixel included in one address of the central zero-cross memory circuit 14, as shown in FIG. 15 described above, the right-side zero-cross memory circuit 24 and the left-side zero-cross memory circuit 34 are respectively located at two adjacent addresses. Matching is detected while the pixels are sequentially shifted according to the position code obtained by dividing the pixels by the interpolation number.

Then, the second counter 60 is incremented (step 1411), and as shown in FIG. 16B, the first counter 50 is set to 0 while the count signal of the second counter 60 is set to 1 (COUNTER2 = 1). While incrementing from 1 to W (step 1407), each part 10 of the line sensor 8
The data stored in the addresses corresponding to the pixels b, 20b, and 30b are compared to detect the coincidence of those data.
Therefore, when COUNTER2 = 1, the address is 0 to (W-1) for the central portion 10b of the line sensor and 1 to (W + 1) for the right portion 20b of the line sensor.
Up to (S-2) to (S + W-2) for the left portion 30b of the line sensor. That is,
The memory data of the right-side zero-cross memory circuit 24 and the left-side zero-cross memory circuit 34 is stored in the central zero-cross memory circuit 14
The above figure, with each pixel shifted from the memory data of
As shown in 15, right side zero-cross memory circuit 24 is provided for the data included in the position code obtained by dividing one pixel at one address of central zero-cross memory circuit 14 into a predetermined number.
Therefore, the coincidence detection is performed while the data included in the position code obtained by dividing the pixels at the two adjacent addresses of the left zero cross memory circuit 34 is shifted.

While incrementing the second counter 60 (step 1411), the coincidence detection is repeated until the count signal of the second counter 60 becomes COUNTER2 = S-1.

That is, the zero-cross memory circuits 14, 24,
A value in which the value of the second counter 60 is the upper bit and the value of the interpolation position counting counter 55 is the lower bit when the memory data of 34 coincide with each other at the zero-cross point corresponds to the deviation amount Xp in the equation (6). . Then, this shift amount is stored as distance data in the data memory circuit 80 in step 1405.

If it is determined in step 1410 that the predetermined shift reading is completed, the process proceeds to step 1412, in which the distance data written in the data memory circuit 80 in step 1405 is output to a photographic lens driving device (not shown) for photographing. The lens moves to a predetermined position and focuses on the subject.

In the above embodiment, the case where the reference value to be compared with the integrated value of the output of the monitor light receiving means 7 is set to four has been described. However, for example, when the reference level is set to two, the circuit Since the configuration can be simplified, it can be configured by providing two level detecting circuits without providing the reference level generating circuit 11d. Reference level 2
An embodiment in the case of a single combination will be described based on FIGS. 17 and 18. The same parts as those in the embodiment shown in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted.

The output of the integrating circuit 11b is the first level detecting circuit.
11j and the second level detection circuit 11k are input, and the first detection level S ₅ and the second detection level S ₆ are respectively compared with the integrated value. These detection levels S ₅ and S ₆ are S ₅ <S ₆ as shown in FIG. 18, and the integrated value is the detection level S ₅
When it becomes larger than the detection level, the detection signal LV ₅ is output from the level detection circuit 11j via the detection signal line 11m and the detection level S ₆
When it becomes larger than the above, the detection signal LV ₆ is sent from the level detection circuit 11k to the drive control circuit 11a via the detection signal line 11n. Drive control circuit 11a, the detection signal amplification factor selection signal for selecting a first gain G ₅ in the case of receiving the LV _5, when receiving a detection signal LV ₆ second amplification factor G ₆ the amplification factor selection signal for selecting, sent to each amplifier circuit 11c, the amplifier circuit 11c is an amplification factor G _5, G _6, which are selected to amplify the output signal of the line sensor 8. In addition, these amplification factors G ₅ and G ₆ are G ₅ >
It is as G ₆ .

Then, as shown in FIG. 18A, the integrated value output from the integrating circuit 11b exceeds the detection level S ₅ within a predetermined time t ₀ , and the detection signal LV ₅ from the first level detecting circuit 11j. Is output, the detection signal L that is output from the second level detection circuit 11k after the detection level S ₆ is exceeded.
By V _6, the transfer signal SH is outputted from the drive control circuit 11a. Further, as shown in FIG. 18B, when the detection level S ₅ is not exceeded within the predetermined time t ₀ , the predetermined time t
_The transfer signal SH is changed by the detection signal LV ₅ output when the detection level S ₅ is exceeded after the passage of _0.
Is output from. Incidentally, the detection level S ₆ in a predetermined time t in ₀
If the detection signal LV ₆ is output beyond the
₆ , the drive control circuit 11a outputs the transfer signal SH.

When the transfer signal SH is output, the shift gate section 8b is opened, and the charge accumulated in the line sensor 8 up to that point, that is, the data relating to the brightness of the object is stored in the register 8c, as in the above-described embodiment. It is transferred and transferred from the register 8c to the amplifier circuit 11c. Then, the output of the line sensor 8 is amplified by the amplifier circuit 11c. The amplification factors G ₅ and G ₆ in the amplifier circuit 11c correspond to the detection levels S ₅ and S _{6 used} for comparison with the integrated value at the time when the transfer signal SH is output. That is, when the transfer signal SH is output by the detection signal LV ₅ output exceeding the detection level S ₅ , the amplification factor G ₅ is used,
When the transfer signal SH is output by the detection signal LV ₆ output exceeding the detection level S ₆ , the amplification factor G ₆ is used. Then, high or low gain G ₆ for the second reference level S ₆ are combined, since the amplification factor G ₅ are combined large for small first reference level S _5, the brightness of the object Even if it changes, the image signal output from the line sensor 8 is converted into a signal having a substantially constant magnitude by the amplifier circuit 11c, and is sent to the A / D converter 9 as in the above-described embodiment.

According to the embodiment shown in FIG. 17, it is not necessary to provide the reference level generating circuit 11d in the embodiment shown in FIG. 1, and the level detecting circuits having different thresholds can be provided. Therefore, the drive control circuit is not necessary to output the reference level selection signal for changing the reference level in 11a, a passage of a predetermined time t _0, a detection signal LV outputted after a predetermined time t ₀ monitors If you have.

Further, in the above description, the data stored in the zero-cross memory circuits 14, 24, 34 for detecting the coincidence are the polarity data and the position data.
For example, when the secondary difference signal DIFF is divided into four and stored at the addresses of the respective parts, a memory capacity of 4 bits is required for one polarity, and 1 bit is required for two positive and negative polarities. Although it is necessary, when storing as polarity data and position code, a memory capacity of 4 bits, that is, 2 bits as a memory of the position code, 1 bit for presence / absence of data and 1 bit as polarity data, is sufficient. Become. Therefore, the required memory capacity can be reduced, and the processing time for matching comparison can be shortened.

Further, the structure in which one line sensor 8 is divided into the left and right and the center is described.
A line sensor may be arranged in each of the centers, and the line sensor control means, the A / D converter 9, the second-order difference calculation circuit 12, the zero-cross detection circuit 13 and the like may be connected to each line sensor. Further, although the description has been given of the case where the A / D converter 9 digitally converts the luminance distribution information and interpolates it, but it is also possible to interpolate the analog data or calculate the secondary difference without interpolating to perform the zero-cross detection. I do not care.

[0068]

As described above, according to the distance measuring apparatus for the passive type autofocus device according to the present invention, the monitor light receiving means is provided, and the integrated values of the outputs of the monitor light receiving means are different in magnitude. Multiple reference levels are compared in order from the smallest one within a predetermined time, and the detection signal corresponding to the maximum reference level is output within the predetermined time, or the detection signal is first output after the elapse of the predetermined time. In case,
Since the charge accumulation in the line sensor is terminated, a detection signal corresponding to a large reference level is output when the brightness of the subject is relatively high, and a small reference level is output when the brightness of the subject is relatively low. A corresponding detection signal is output and the charge accumulation ends. Then, the image signal output from the line sensor is amplified with a small amplification factor for a large reference level and a large amplification factor for a small reference level. When the brightness is low, the amplification factor is large, and the amplification factor is large. Therefore, by setting the relationship between the plurality of detection levels and the plurality of amplification factors to be predetermined, it is possible to perform the detection processing with the signals related to the zero cross detection being set to substantially the same level regardless of the brightness of the subject.
Therefore, the time until the brightness of the subject is captured by the line sensor and the charges are accumulated is changed according to the brightness of the subject, and distance measurement can be performed in a short time according to the brightness of the subject.

Therefore, it is possible to provide a camera equipped with a range finder which is highly versatile and has little influence on the state of the subject because distance measurement is possible for a subject having a wide luminance range.

Further, since the zero-cross data of the second-order difference of the subject luminance distribution is compared, the distance data can be obtained with high accuracy without depending on the subject luminance distribution pattern on the line sensor. .

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of a line sensor control unit that controls charge accumulation and transfer of accumulated charge of a line sensor according to a first embodiment of the range finder for a passive autofocus device. is there.

FIG. 2 is a time chart showing the end of charge accumulation by the line sensor in the line sensor control means according to the first embodiment.

FIG. 3 is a circuit block diagram of the distance measuring device for the passive autofocus device.

FIG. 4 is a side view showing a schematic structure of a light receiving sensor.

FIG. 5 is a circuit block diagram of a quadratic difference calculation circuit for A / D converting the output of the line sensor and digitally processing the quadratic difference.

FIG. 6 is a block diagram of an interpolation calculation circuit that interpolates an output signal of a quadratic difference calculation circuit by digitally processing and linearly approximating the signal.

FIG. 7 is a circuit diagram of a zero-cross detection circuit that detects a zero-cross point of interpolated data of a second-order difference signal obtained by a second-order difference calculation circuit.

FIG. 8 is a time chart of output signals of a line sensor, an A / D converter, a second-order difference calculation circuit, and a zero-cross detection circuit.

FIG. 9 is a block diagram of a zero-cross data match detection circuit.

FIG. 10 is a zero-cross memory circuit in which data obtained by the line sensor is captured when the light of an object is captured by the line sensor and charge accumulation is started and the integrated value of the accumulated voltage reaches a predetermined level. Is a flow chart showing a procedure for writing into the line sensor, including a part of the left part of the line sensor.

FIG. 11 is a flowchart showing a procedure for writing data obtained from the line sensor to the zero-cross memory circuit, which is another part relating to the left part of the line sensor.

FIG. 12 is a flowchart showing a procedure for writing data obtained from a line sensor into a zero-cross memory circuit, which relates to a central portion of the line sensor.

FIG. 13 is a flowchart showing a procedure for writing data obtained from a line sensor to a zero-cross memory circuit, which relates to the right part of the line sensor.

FIG. 14 is a flow chart 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. 15 is a conceptual diagram for explaining a procedure for detecting a match between data stored in a zero-cross memory circuit.

FIG. 16 is a diagram illustrating an operation procedure for reading and comparing data stored in a zero-cross memory circuit.

FIG. 17 is a block diagram illustrating a configuration of a line sensor control unit that controls charge accumulation and transfer of accumulated charge of the line sensor according to the second embodiment of the distance measuring apparatus for the passive autofocus device. is there.

FIG. 18 is a time chart showing the end of charge accumulation by the line sensor in the line sensor control means according to the second embodiment.

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]

 7 Monitor light receiving means 8 Line sensor 9 A / D converter 10, 20, 30 Light receiving sensor 10b Line sensor central part 20b Line sensor right part 30b Line sensor left part 11 Line sensor control means 11a Drive control circuit 11b Integrating circuit 11c Amplifying circuit 11d Reference level generation circuit 11e Level detection circuit 11j First level detection circuit 11k Second level detection circuit 12 Second-order difference calculation circuit 13 Zero cross detection circuit 14, 24, 34 Zero cross memory circuit 25, 35 Address calculation circuit 40 Control circuit 50 1st counter 55 Counter for interpolation position counting 60 2nd counter 70 Match detection circuit 80 Data memory circuit

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[Procedure amendment]

[Submission date] October 22, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Title of invention

[Correction method] Change

[Correction content]

Title of the Invention Distance measuring device for passive autofocus device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03B 13/36

Claims (3)

[Claims] 1. A set of three light receiving sensors having a line sensor for capturing a luminance distribution of an object, a second order difference calculating circuit for calculating a second order difference between output signals of the light receiving sensors, and the second order difference calculating circuit. A zero-cross detection circuit for detecting a zero-cross point of the output signal of the above, and a zero-cross memory circuit for individually storing the zero-cross behavior signal obtained by the zero-cross detection circuit for each of the three sets of light-receiving sensors, and each of the zero-cross memory circuits. The zero-crossing behavior signal obtained from the reference light-receiving sensor is used as a reference, and a coincidence detecting circuit for comparing the stored zero-crossing behavior signals to detect these coincidences. On the other hand, the zero-cross behavior signals obtained from the other two light-receiving sensors are sequentially shifted, and the coincidence of these zero-cross behavior signals is determined as above. In a rangefinder for a passive autofocus device, which detects the coincidence detection circuit and calculates the distance from the shift amount to a subject, a monitor light receiving means for monitoring the average brightness of the subject, and the monitor light receiving means. Output from the line sensor, and a level detection circuit that has a detection level that is compared with the integrated value in the integration circuit and that outputs a detection signal when the integrated value reaches the detection level. An amplification circuit capable of amplifying the image signal with a plurality of amplification factors having different sizes; and a drive control circuit for driving the amplification circuit by selecting an appropriate amplification factor from the plurality of amplification factors. Therefore, the detection levels of the level detection circuit are prepared in the same number as the number of the amplification factors with different sizes, and at the same time, the plurality of detection levels are reduced. From the highest to the highest amplification factor, the drive control circuit reduces the detection levels to the level detection circuit each time the detection signal is output from the level detection circuit within a predetermined time. When the detection signal for the maximum detection level is output from the level detection circuit within the specified time, the detection signal is used, or the first detection is output after the specified time has elapsed. A passive type auto characterized by terminating the charge accumulation in the line sensor by the signal, causing the line sensor to output an image signal, and amplifying the image signal with an amplification factor corresponding to the detection level at the end of the charge accumulation. Distance measuring device for focus device. 2. Upon receiving an output signal of the drive control circuit,
The range finder for a passive autofocus device according to claim 1, wherein the level detection circuit is provided with a reference level generation circuit for providing a detection level to be used for comparison with the integrated value. 3. A set of three light receiving sensors having a line sensor for capturing a luminance distribution of an object, a second order difference calculating circuit for calculating a second order difference between output signals of the light receiving sensors, and the second order difference calculating circuit. A zero-cross detection circuit for detecting a zero-cross point of the output signal of the above, a zero-cross memory circuit for individually storing the zero-cross behavior signal obtained by the zero-cross detection circuit for each of the three sets of light-receiving sensors, and each of the zero-cross memory circuits. The zero-crossing behavior signal obtained from the reference light-receiving sensor is used as a reference, and a coincidence detecting circuit for comparing the stored zero-crossing behavior signals to detect these coincidences. On the other hand, the zero-cross behavior signals obtained from the other two light-receiving sensors are sequentially shifted, and the coincidence of these zero-cross behavior signals is determined as above. In a rangefinder for a passive autofocus device, which detects the coincidence detection circuit and calculates the distance from the shift amount to a subject, a monitor light receiving means for monitoring the average brightness of the subject, and the monitor light receiving means. And a detection level for inputting an integrated value in the integration circuit and having a detection level for comparison with the integrated value, and outputting a detection signal when the integrated value reaches the detection level. A plurality of level detection circuits having different sizes, an amplifier circuit capable of amplifying the image signal output from the line sensor with a plurality of amplification factors having different sizes, the amplification circuit having the plurality of amplification factors. And a drive control circuit that drives by selecting an appropriate amplification factor from among the plurality of level detection circuits. Corresponding in order from the one with the highest amplification factor, the drive control circuit selects from the one with the smallest detection level each time the detection signal is output from the level detection circuit within a predetermined time, and the detection signal with respect to the maximum detection level is selected. Is output from the level detection circuit within a predetermined time, or by the first detection signal output after the elapse of the predetermined time, the charge accumulation in the line sensor is terminated and the line sensor outputs A distance measuring device for a passive autofocus device, which outputs an image signal and amplifies the image signal at an amplification factor corresponding to a detection level at the end of charge accumulation.