JPH0454775A - Focusing detecting device - Google Patents

Abstract

PURPOSE:To decrease the scale of an electric circuit and a memory and to attain high speed processing by using a single shift register so as to read a photoelectric conversion signal by one line simultaneously and storing the signal into an analog memory without any modification. CONSTITUTION:An analog memory section 101b consists of plural analog memories storing tentatively an output of each photoelectric conversion element being a component of a light receiving section 101a. A select register 101c reads an output of each line of each photoelectric conversion element being a component of the light receiving section 101a and latches a read photoelectric conversion signal to each analog memory of an analog memory section 101b. The register 101c is formed by integrating shift registers corresponding to each line. Through the constitution above, an output of each photoelectric conversion element being a component of the light receiving section 101a is latched in each analog memory of the analog memory section 101b at a high speed by controlling the select register 101c with a clock signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a focused point detection device used in a camera or the like.

[Prior art] Conventionally, as a focused point detection device, for example,
2. Description of the Related Art A device is known that detects two subject images using a photoelectric conversion device and obtains a focused point from a phase difference between the two detected subject images. Further, among such focused point detection devices, one using an area sensor as a photoelectric conversion device is known. In a focused point detection device that uses an area sensor as a photoelectric conversion device, the output (video signal) of each photoelectric conversion element constituting the area sensor is usually extracted from only the video signal of an arbitrary region. It is stored in memory and used to detect the focal point.

Conventionally, the following techniques are known as techniques for extracting a video signal of an arbitrary area from an area sensor and storing it in a memory.

The first technique is to provide an address decoder circuit within the photoelectric conversion device, and use this address decoder circuit to determine the address (X coordinate and
The video signal is read out by directly specifying the coordinates) and stored in the memory.

(Frame Interlfne Transfer
-CCD), etc. That is, a register corresponding to each pixel is provided, and one line of video signals is simultaneously taken into this register.

[Problems to be Solved by the Invention] However, the above techniques have the following problems.

When extracting a video signal using an address decoder circuit, it is necessary to specify the address of each pixel in terms of the X coordinate and the X coordinate, which causes a problem in that the circuit scale becomes large and therefore the cost becomes high. In addition, since each pixel must be read out, A/D converted, and then stored in a memory, there is also the problem that the time required for "reading" and "storing" is long.

In addition, if the video signals for one line are sequentially read out and then the video signals outside the area used for in-focus point detection are to be discarded, a memory must be provided for every pixel, which requires a huge memory capacity. There was the issue of it becoming a thing.

In particular, when such an area sensor is used in a focal point detection device, only information for a few lines is actually required, which is wasteful.

The present invention was attempted in view of the problems of conventional focused point detection devices as explained above, and provides a focused point detection device that has a small electric circuit and memory and is capable of high-speed processing. The purpose is to

[Means for Solving the Problems] A focused point detection device of the present invention includes an imaging optical system that forms an image of a light beam from a subject, and a photoelectric conversion that photoelectrically converts the subject image formed by the imaging optical system. and a focused point detecting means for detecting a focused point of the imaging optical system based on a photoelectrically converted signal from the photoelectrically converting means, wherein the photoelectrically converting means detects a focused point for each pixel. A plurality of photoelectric conversion elements that output conversion signals, a plurality of analog memories that temporarily store the outputs of the photoelectric conversion elements, and a plurality of analog memories that read out the photoelectric conversion elements and store the read photoelectric conversion signals in the analog memory. It is equipped with a shift register that latches the data.

[Function] According to the focused point detection device of the present invention, when extracting a video signal from a certain area (area used for focused point detection) of a photoelectric conversion device (photoelectric conversion means), the address of each pixel can be directly specified. Instead of reading out the video signal using a single shift register, the photoelectric conversion signals for one line are simultaneously read out and read into the analog memory as they are, so the scale of the electric circuit and memory can be small, and High-speed processing becomes possible.

[Embodiments] Hereinafter, embodiments of the present invention will be described, taking as an example a case where the in-focus point detection device of the present invention is mounted on a single-lens reflex camera.

FIG. 1(a) is a block diagram schematically showing the configuration of an electric circuit system of a single-lens reflex camera equipped with the in-focus point detection device of the present invention. In the figure, 101 is a focused point detection circuit as a focused point detection device of the present invention, 102 is a photographic lens that guides the light flux from the subject to a photographic film (not shown), the focused point detection circuit 101, etc., and 103 is a photographic lens. 1
02 is a position detection circuit, and 04 is a drive control circuit that moves the photographing lens 102 to the in-focus point.

The drive control circuit 104 uses the information regarding the in-focus point input from the in-focus point detection circuit 101 and the information regarding the position of the photographing lens 102 input from the position detection circuit 103.
The photographing lens 102 is moved to the in-focus point.

FIG. 1(b) is a block diagram schematically showing the configuration of the photoelectric conversion section of the focused point detection circuit 101 shown in FIG. 1(a). In the figure, 101a is a light receiving section consisting of a plurality of photoelectric conversion elements, 101b is an analog memory section consisting of a plurality of analog memories that temporally stores the output of each photoelectric conversion element constituting the light receiving section 101a, and 101c is a light receiving section. 10
The output of each line of each photoelectric conversion element constituting 1a is read out, and the read photoelectric conversion signal is stored in the analog memory section 1.
This is a select register to be latched in each analog memory of 01b. The select register 101C is configured by integrating shift registers corresponding to each line. In such a configuration, the select register 101c
By controlling the clock, the output of each photoelectric conversion element constituting the light receiving section 101a can be latched into each analog memory of the analog memory section 101b at high speed.

FIG. 2 is a block diagram showing one embodiment of the configuration of the single-lens reflex camera shown in FIG. 1.

As shown in the figure, in this embodiment, the in-focus point detection circuit 101 is an AF optical system that functions as an imaging optical system that splits the light beam from the subject guided through the photographic lens 102 into an image. 201, a photoelectric conversion device 202 as a photoelectric conversion means for converting the light beam imaged by the AF optical system 201 into a video signal; a photoelectric conversion device 202 for detecting a focal point position; and a photographing lens 102;
AF as a focusing point detection means for calculating the driving amount of
A control circuit 203 , a monitor circuit 204 that monitors the video signal output from the photoelectric conversion device 202 and supplies it to the AF control circuit 203 , and a monitor circuit 204 that applies frequency band limitation to the video signal output from the photoelectric conversion device 202 and supplies it to the AF control circuit 203 .
It is constituted by a filter circuit 205 that supplies Further, the position detection circuit 103 includes a light emitting element 206 for irradiating light onto a mirror provided on the photographic lens 102 and a photoelectric converter that receives light reflected by a mirror provided on the photographic lens 201 and converts it into an electrical signal. It is configured by the device 207.

Furthermore, FIG. 3 schematically shows the configuration of the optical system of the single-lens reflex camera according to this embodiment. In Figure 3,
Components denoted by the same reference numerals as those in FIG. 1 or 2 indicate the same components as in FIG. 1 or 2, respectively. Further, 301 is a mirror for reflecting the light flux from the subject guided through the photographic lens 201, 302 is a condenser lens, and 303 is a half mirror that divides the light flux that has passed through the condenser lens 302 into two directions. A finder 305 for the photographer to view the luminous flux is a display LED that allows the photographer to visually view various displays superimposed on the luminous flux from the subject through the finder.

In such an eye reflex camera, the light flux from the subject guided through the photographing lens 102 is reflected by the mirror 301, passes through the condenser lens, and reaches the AF optical system 201 by the half mirror 303 and the finder. It is divided into a luminous flux reaching 304. The light flux that has reached the AF optical system 201 is converted into a video signal by a photoelectric conversion device 202, and is used for in-focus point detection and the like. Further, the light flux that has reached the finder 304 is visually observed by the photographer.

Next, regarding the main components of the focused point detection circuit 101,
Explain in detail.

First, the AF optical system 201 will be explained.

The AF optical system 201 is for pupil-dividing a luminous flux from a subject that has passed through the photographic lens 102 and the condenser lens 302, and forms an image on the surface of a light receiving section (described later) of the photoelectric conversion device 202.

FIG. 4 shows a photographing lens 102 and a condenser lens 302.
The optical relationship between the AF optical system 201 and the AF optical system 201 is conceptually shown. In the figure, 201a and 201b are the AF optical system 2
01 is an AF lens, 401 is a photoelectric conversion device 20
2, 402a is the subject image formed by the AF lens 201a, 402b is the AF lens 201
The subject images formed by b are shown respectively.

The in-focus point detection circuit 101 of this embodiment calculates the image interval between these two subject images 402a and 402b, calculates the distance between the single-lens reflex camera and the subject based on the calculated image interval, and calculates the distance between the single-lens reflex camera and the subject based on the calculated image interval. The in-focus point is detected based on the

Next, the photoelectric conversion device 202 will be explained.

The photoelectric conversion device 202 converts the subject image 402 shown in FIG.
This is for converting signals a and 402b into video signals.

FIG. 5 schematically shows the internal configuration of the photoelectric conversion device 202. In the figure, 501 is a light receiving section having a plurality of photoelectric conversion elements arranged two-dimensionally, 502 is an analog memory section for storing the output (video signal) of each photoelectric conversion element constituting the light receiving section 501, and 503 is an analog memory section for storing the output (video signal) of each photoelectric conversion element constituting the light receiving section 501. V shift register (select register 101c) for reading the video signal from the light receiving unit 501 and storing it in the analog memory unit 502
, 504 is an H shift register for reading out the video signal stored in the analog memory section 502, and 505 is an H shift register for reading out the video signal stored in the analog memory section 502. ), an output circuit for outputting to
06 is a control circuit that controls the entire photoelectric conversion device 202.

The light receiving section 501 is configured by two-dimensionally arranging pixel cells each having a photoelectric conversion element. In I56, S(i
, j) conceptually represents one of the pixel cells that constitute the light receiving section 501.

Note that "i" indicates the coordinate of the pixel cell in the horizontal direction (horizontal direction in the figure), and "j" similarly indicates the coordinate in the vertical direction (vertical direction in the figure). Further, R is a reset signal input terminal, Vj is a read signal input terminal, and SOi is a video signal output terminal. Each pixel cell S (1
, jo), S (2°JO)l . . . have a common readout signal input terminal Vjo. That is, the video signals of the pixel cells S(1, jo) S(2, jo), . . . are the scanning lines Vj. are read out simultaneously by turning on. In addition, each pixel cell S (io, 1
).

5(i(,,2),... video signal output terminal 5Oi(
.

has been standardized.

FIG. 6(a) shows the electric circuit configuration of the pixel cell of the light receiving section 501. In this example, as a photoelectric conversion element, S
i T (Static Induction Lsa
geSenser) was used. Also, in the figure, M
TR is a reset transistor, and MTV is a signal reading transistor. The light receiving section 501 of this embodiment is configured by two-dimensionally arranging such pixel cells. Further, the photoelectric conversion characteristics of SiT are shown in FIG. 6(b). In the figure, the horizontal axis is the amount of light received by the SiT, and the vertical axis is the amount of light received by the SiT.
shows the output value. In this way, in SiT, the amount of received light is proportional to the output value up to a certain level, so it is possible to obtain a video signal with a value corresponding to the amount of light. In addition, in FIG. 5, D(#], k), D(I2.k), D(
#s, k) each indicate a pixel cell in which SiT is shielded from light by a filter. These pixel cells are used to correct the output of the pixel cell S(i, j) that is not shaded to remove the influence of dark current.

The analog memory section 502 has a plurality of memory cells M(m,n) arranged two-dimensionally.

Note that "-m" indicates the horizontal coordinate of the pixel cell, rnJ
similarly indicate the coordinates in the vertical direction. In the horizontal direction, the number of memory cells M (m, n) is the pixel cell S (i.

The number is the same as j). In addition, memory cell M (m, n
) may be determined in accordance with the vertical length of the area where the video signal is extracted for detection of the in-focus point, but here it is assumed to be n. FIG. 7 shows the configuration of the analog memory section 502. Note that in FIG. 7, only one line of memory cells in the vertical direction is shown. In the figure, 701 is a switching transistor for opening and closing the wiring between the video signal output terminal SO1 of the pixel cell of the light receiving section 501 and each memory cell, and 702-1 to 70
2-n is a transistor for selecting a memory cell when storing a video signal; 703-1 to 70B-n are capacitors serving as an analog memory for storing video signals;
4 is a transistor for selecting a memory cell when reading a video signal, 705 is a power transistor for amplifying the charge (video signal) accumulated in the capacitor 703-1, and 706 is a transistor for connecting each memory cell to the ground. This is a reset transistor that opens and closes the wiring.

Each memory cell M (1, no) is arranged in the horizontal direction.

The read control line M n (, of M(2, no), . . . is shared. That is, the read control line M n (,
o) + M (2, no), +++ is the read control line M
By turning on n (, the video signals are read simultaneously. Also, each memory cell M (mo,
1), M (mo, 2), ... video signal output terminal 5O
1o is also standardized. Here, each pixel cell S (1, jo), S (2, jo), . . . arranged in the horizontal direction
, and each pixel cell 5(io,'l) arranged in the vertical direction.

5 (io, 2), ... video signal output terminal So i (
1 are also standardized, as described above.

Therefore, when the shift register 503 turns on the read signal input terminal Vjo and the read control line M n O at the same time, each pixel cell S (1
, jo), S (2, jo), - are respectively output from each memory cell M arranged in the horizontal direction.
(1, no), M (2゜no) +...
・Memorized at the same time. In this way, in the photoelectric conversion device 202 of this embodiment, the video signal for one line in the horizontal direction output from the light receiving section 501 can be stored in the analog memory section 502 at the same time. In addition, each memory cell M (mO, 1), M (mo
, 2) , - read control line Hm (1 is shared, so when this read control line Hm□ is turned on, each memory cell M (mo, 1), M (mo, 2)
) and - simultaneously (that is, averaged) output video signals.

FIG. 8(a) shows the structure of the shift register 503. In the figure, BSR is a basic block, vSP is an input pulse for inputting a start pulse, and VR is an input terminal for inputting two types of tarok signals. Also, Fig. 9(a)
The configuration of the basic program BSH is shown in FIG. In the figure,
H1 and H2 are clock signals, and SP is a start pulse, respectively. Further, FIG. 9(b) shows a timing chart during operation of the basic block BSH.

As shown in the figure, the output of each inverter is shifted to the next stage basic program BSH by a clock signal H1 and output by a clock signal H2.

As shown in FIG. 8(a), ■Shift register 503
The outputs of each basic block BSH are arranged in such a way that those that give a signal to the read signal input terminal Vj of the light receiving section 501 and those that give a signal to the read control line Mn of the analog memory section 502 are arranged.

In such a configuration, as shown in FIG. 8(b), if the start pulses input from vSP are shifted by an appropriate number of locks and two are input from vSP, Vj and Ml
, Vj+2 and M2, Vj+3 and M3, and so on. Therefore, it is possible to sequentially store the video signal output from the light receiving section 501 in the analog memory section 502 for each line in the horizontal direction.

The H shift register 504 includes a first shift register that selects a block from which a video signal is extracted from memory cells M (m, n) of the analog memory section 502, and a and a second shift register that sequentially reads out video signals from memory cells M (m, n). In Figure 10, H
The configuration of shift register 504 is shown. In the figure, HA
R and HAL are the first shift registers mentioned above, HBR
and HBL is the above-mentioned second shift register, BSR is a basic block, and H5PI.

HSP2. H5PI' and H3P2' are each HA
Input terminal for inputting start pulse to R, MAL, HBR, HBL, HRI, Hl2゜HRI'HR2'
are input terminals that input two types of clock signals to HAR, HALHBR, and HBL, respectively, and C1 and C2 are wirings that connect the outputs of the first shift registers MAR and MAL and the outputs of the second shift registers HBR and HBL, respectively. This is an input terminal for inputting signals for opening and closing. As explained using FIG. 4, in this embodiment, since it is necessary to read the video signal for each of the two subject images formed by pupil division, the light receiving sections corresponding to these two subject images are The first shift register and the second
Two shift registers were provided for each. Note that the configuration of basic block BSH is similar to basic block BSR of the V shift register shown in FIG. 9. However, the output of each BSR of the first shift registers HAR and HAL is outputted to the second shift register HBR and H, respectively.
It is connected to the output of the first stage BSR of the corresponding block among the BL BSRs. Also, the second shift register H
The output of each BSR of BR and HBL is connected to each read control line Hm of the analog memory section 502.

The operation of H shift register 504 will be explained. First, in order to select a block from which a video signal is to be read using the first shift registers MAR and HAL, H
Set 5PI' and H3P2' to "low J," set HRI' and HR2' to "high," and set the start pulse from H3PI and HSP2 and the clock signal from HRI and HR2, respectively, according to the timing chart shown in FIG. 9(b). Enter in the same way. When the start pulse or the desired block is reached, the second shift registers HBR and H
In order to read the video signal from the analog memory section 502 by BL, input terminals C1 and C2 are set to "high", the output of the first stage BSR of this block is set to "high", and input terminal C is set to "high".
I.

After returning C2 to "high", clock signals are input from HR1' and HR2' to sequentially shift the "high" output of the first stage BSH. As a result, the analog memory section 5
Each readout control line Hm corresponding to an area (block) from which a video signal of 02 is to be read is sequentially turned on, and each read video signal is sent to the output circuit 505.

Next, the AF control circuit 203 will be explained.

The AF control circuit 203 first performs a correlation calculation using the video signal input from the photoelectric conversion device 202 via the filter circuit 205. In FIG. 11, a photoelectric conversion device 20
2 shows the relationship between the video signals of the subject images (image A and image B, respectively) read out in two blocks of No. 2. Correlation calculation is performed by shifting the distance between image A and image B by one pixel (the amount by which the images are shifted at this time is referred to as the "shift amount"), and calculating the correlation calculation value Σ1ae--b,I at any time. According to
Find the distance between two images A and B. That is, the amount of deviation when the correlation calculation value becomes the minimum is the distance between the two.

Next, standard value calculation is performed. The standard value calculation is to obtain a value (standard value) obtained by dividing the correlation calculation value obtained by the above-mentioned correlation calculation by the contrast value.

Finally, interpolation calculations are performed. FIG. 12 is a graph for explaining this interpolation calculation. In the figure, the vertical axis is the standard value of the correlation calculation value, and the horizontal axis is the amount of deviation. In addition, M indicates the point where the standard value is minimum, and Ll and R1 are respectively M
It shows a point shifted forward or backward by one pixel unit. As shown in the figure, Ll.

Straight line y1 passing through M and the point with the larger standard value among R1
The intersection point S between the straight line y1 whose slope is relative to the vertical axis and the target straight line y2 passing through the point with the smaller standard value among L and R is the point that gives the amount of deviation after the interpolation calculation. . These straight lines are located at point L2, which is shifted by one pixel from L, R1, respectively.
．． Pass through R2.

In addition, the slope of these straight lines is when R2>R2;('L+ -M) + (R2M) + (R2-R1)
When L2≦R2; (R2-R+) +(, RI M) +(R2-L
l).

Next, the position detection circuit 103 will be explained in detail.

As shown in FIG. 2, the position detection circuit 10B receives light reflected by a light emitting element 206 for irradiating light onto a mirror provided on the photographic lens 102 and a mirror provided on the photographic lens 201. It is constituted by a charging conversion device 207 that converts into an electric signal. An example of a specific configuration of this position detection circuit 103 is shown in FIG. In the figure, 1301 is a frame for holding the lens group (not shown) of the photographing lens 102, 1302 is an actuator for moving the frame 1301, 1303 is a mirror provided on the actuator 1302, and 1304 is a mirror 1.
This is a mask provided on the surface of 303. Further, the light emitting element 206 includes a light source 1306 and a diffusion plate 1305 that diffuses the light from the light source 1306. Further, the photoelectric conversion device 207 includes a line sensor 1307,
The output of this line sensor unit 307 causes the photographing lens 10 to
and a control circuit 1308 that detects the position of 2.

In such a configuration, the light from the light source 1306 becomes diffused light when passing through the diffuser plate 1305, and the light from the light source 1306 becomes diffused light.
The light is reflected by the line sensor 1307 and photoelectrically converted by the line sensor 1307.

Here, since the mask 1304 is provided on the surface of the mirror 1303, the amount of light reaching the line sensor 1307 has a concave distribution. The control unit 1308
The amount of movement of the photographing lens is detected based on the change in the intensity distribution of the signal output from the line sensor 1307.

FIG. 14(a) is an electric circuit diagram showing the configuration of a light receiving section that constitutes the line sensor 1307. In this embodiment, as the photoelectric conversion element, like the photoelectric conversion device 202 described above,
SiT was used. Further, LRT is an MO5 type transistor for reset. Line sensor 1307 of this embodiment
is constructed by arranging such light receiving sections in a line.

The photoelectric conversion characteristics of SiT are shown in FIG. 14(b). In the figure, the horizontal axis shows the amount of light received by the SiT, and the vertical axis shows the output value of the SiT. As in the case of the photoelectric conversion device 202 described above, in the SiT, the amount of received light is proportional to the output value up to a certain level, so it is possible to obtain a video signal having a value corresponding to the amount of light.

FIG. 15 shows changes in the light quantity distribution of light reflected by the mirror 1303 and the mask 1304. As shown in the figure, when the mirror 1303 and mask 1304 are moved by driving the actuator 1302, (a)
The light amount distribution changes in the order of →(b)-'(C).

Further, FIG. 16 shows the overall configuration of the line sensor 1307. In the figure, 1601 is a light receiving unit group, 1602 is a decoder, 1603 is a D/A converter, and 1604.16
05.1606 is a comparator, 1607 is a judgment circuit,
1608 (1).

1608 (2), ... are capacitors as memory, 1609 (1) a, 1609 (1) b, 1609
(1)c, 1609 (2)a, 1609 (2)b.

1609 (2) C,... are gate transistors,
1610(1), 1610(2)-- are memory reset transistors.

The operation of the position detection circuit 103 will be explained below using FIG. 17.

First, the gate transistor is 16o9(1)a
, 1609 (2)b, 1609 (3)c.

Next 1: 1609 (2) a, 1609 (3) b.

1609(4)C, etc. Step 5T1701) Based on the result of this scan,
The initial position of the mask 13o4 (i.e., the photographic lens 10
2 initial position) is detected (step 5T1702).

Next, the control circuit 1308 controls the position xO to which the mask is to be moved.
Step 5T170B), based on this XQ,
Then, three types of signal values to be supplied to the D/A converter 1603 are determined (step 5T1704). These three types of signal values are determined at position X when mirror 1303 and mask 1304 move and reach position XQ. 1609(x.

-1)a, 1609 (XO)b,, 1609 (xO
+1) means the output value that c should take. The D/A converter 1603 converts each supplied signal into an analog signal and outputs it to 1604, 1605, and 1606. Next, the light receiving section corresponding to the position xo to which the mirror 1303 and the mask 1304 are moved, and the transistors 1609 (Xo-
1) a, 1609 (xo) b, 1609 (Xo +
1) Turn on c, step 5T1705), and start driving the actuator (step 5T1706).Thereafter, use the comparators 1604, 1605, and 1606 to set position -1° Light receiving part 1 corresponding to XO, XO+1
601 and the value of the signal output by the D/A converter 1603, step 5T1707),
If the two match, it is assumed that the photographing lens 102 has reached xO, and the drive of the actuator is stopped (step 5T1708), thereby ending the position detection.

FIG. 18 shows the position x(3-1,xO) when the mirror 1303 and the mask 1304 are moved.

x(, +1). The D/A converter 1 is
What is necessary is to set the level of the output signal of 603.

Next, the photographing lens 102 will be explained in detail.

FIG. 19 is a diagram showing an example of the configuration of the photographing lens 102. As shown in the figure, the photographic lens 102 has G1.
G2. It consists of three G3 lens groups, and all of these lens groups are driven when a focused point is detected.

Note that when the in-focus point is detected, as shown in Fig. 20, the object area may be located diagonally away from the center of the object area for which the in-focus point is detected, or it may be out of focus. There are times when I put it away. However, this problem can be solved by moving the position of the lens group G1.

FIG. 21(a) is a diagram for explaining the state of the in-focus point when the lens group G1 is shifted by 0.3 mm from the in-focus position in the negative direction (to the left in the figure). b)
is a diagram for explaining the state of the in-focus point when the lens group G1 is shifted from the in-focus position by 0.3 mm in the plus direction (to the right in the figure). In the figure, F and F2 each conceptually indicate the position of the subject that is in focus. Furthermore, as shown in FIG. 20, d and r are the length of the diagonal line of the imaging plane (that is, the surface of the film) and the amount of deviation in the diagonal direction from the center of the subject area where focus detection is performed. It shows.

For example, as shown in FIG. 21(a), when the distance between the subject for which in-focus point detection is to be performed and the lens group G1 is 1400 mm, if the lens group G1 is shifted 0.3 mm in the negative direction from the in-focus position, , the focus state at the center of this subject is almost the same, but the focus is 0 in the diagonal direction from the center of the subject.
．． At a position shifted by 2d, the distance to lens group G1 is 1.
Focus can be obtained at a distance of 120 mm. On the other hand, as shown in FIG. 21(b), if the lens group G1 is shifted 0.3 mm in the positive direction from the in-focus position, the in-focus state at the center of the subject remains almost the same, but At a position shifted by 0.2d diagonally from the center, a focused state is obtained at a position 1820 mm away from the lens group G1.

By utilizing such a property, it is possible to simultaneously bring into focus the center of the subject area for which in-focus point detection is to be performed and a position diagonally shifted from this center.

Next, the operation sequence when such a -eye reflex camera detects a focal point will be explained using FIG. 22.

First, a subject area for in-focus point detection is determined (step 5T2201). For example, the subject area corresponding to the center of the finder 304 when the first release is turned on may be used as the subject area for in-focus detection. Subsequently, the photoelectric conversion device 202 is reset (step 5T2202).

Next, processing is performed to determine the integration time of each photoelectric conversion element constituting the light receiving section 501 when capturing a video signal. First, perform a peak monitor. This peak monitor uses pixel cells S (i, j), S (i+1.
), . . . , S(i, j). Turn on each of these pixel cells and turn on the H shift register 504 (step 5T2203), simultaneously start a timer (step 5T2204), and monitor the peak value (maximum value) of the output values of each pixel cell using the monitor circuit 204. While measuring sequentially (step 5T22D6
), time is measured by a timer (step 5T22).
05). When the peak value reaches a predetermined value before a predetermined time elapses (when monitoring ends), the value of the readout amount p is set to "1". That is, when performing in-focus point detection, integration is performed only for one line of pixel cells in the horizontal direction.

Next, the video signal is read out. First, the shift register 503 imports the output of the pixel cells of one line into the analog memory section 502 (step 57).
2208), then only the necessary ones (
That is, only the outputs of the two pixel blocks for which in-focus point detection is to be performed) are read out by the H shift register 504 (step 5T2209). The read video signal is output from the output circuit 505, and after high frequency components are removed by the filter circuit 205, it is converted to an A/D converter (not shown).
/D conversion is completed (step 5T2210). The A/D converted video signal is subjected to illuminance correction, dark current correction, etc. (correction 1)
(Step 5T2211), the above-mentioned correlation calculation and interpolation calculation are performed to calculate the amount of movement of the photographing lens 102 (Steps 5T2212.5T221B).

Subsequently, an error in the amount of movement caused by the position of the subject area to be focused in the light receiving unit 501 is corrected (correction 2) (step 5T2214).

Thereafter, the photographing lens 102 is moved as described above (step 5T2215), and in-focus point detection is completed.

On the other hand, in step 5T2205, if the timer overflows before the output value of the pixel cell reaches a predetermined value, the monitor value is A/D converted (step 5T2216), and then the value of the readout amount p is calculated by calculation (
Step 5T2217). Next, the video signal is read out.

First, the outputs of the pixel cells of the corresponding line are sequentially taken into the analog memory section 502 line by line as described above by the shift register 503 (step 5T2218). Subsequently, by simultaneously turning on the transistors 702 (1) to 702 (it) of the analog memory section 502, each stored data (video signal) in the vertical direction is averaged. Similarly, the stored data is averaged for each vertical line, and only necessary data is read out by the H shift register 504 (step 5T2219). Then, step 5T2210 above
Execute the following steps to finish in-focus point detection.

In this way, by using the focused point detection device of this embodiment, it is possible to reduce the circuit scale and speed up the processing. Furthermore, since external control becomes easy, it is also possible to reduce the circuit scale of the entire -eye reflex camera.

Note that although SiT was used as the photoelectric conversion element in this embodiment, other photoelectric conversion elements may be used. Furthermore, although a linear actuator is used, any actuator may be used as long as the displacement is ultimately linear. Furthermore, by performing correlation calculation or interpolation calculation using the output of the line sensor, it becomes possible to detect the amount of movement with higher accuracy. In addition, the mask may be of any type as long as it can provide a periodic pattern with contrast.

Next, a second embodiment of the focused point detection device according to the present invention will be described.

In the in-focus point detection device according to this embodiment, (1) the shift register is replaced with the H shift register 50 in the first embodiment.
4, it is constructed of a first shift register that selects a block and a second shift register that sequentially reads out video signals within the block selected by the first shift register.

FIG. 23 shows the configuration of the V shift register according to this embodiment. In the figure, HRI is the above-mentioned first shift register, HR2 is the above-mentioned second shift register, BSR is a basic block, SP is an input terminal for inputting a start pulse to VRI, VRI and Vl2 are HRI and HR2, respectively.
C is the input terminal for inputting two types of clock signals to the
This is an input terminal for inputting a signal for opening and closing the wiring connecting the outputs of the second shift registers MAR and HAL to the outputs of the second shift registers IBR and HBL.

In addition, in the V shift register shown in FIG. 23, the output of each basic block BSH is one that provides a signal to the read signal input terminal Vj of the light receiving section 501, and one that provides a signal to the read signal input terminal Vj of the light receiving section 501, and one that supplies a signal to the analog memory section 50.
2, which gives a signal to the read control line Mn, and
Items that do not output are arranged alternately. In such a configuration, when a start pulse with a length of two clocks is input from vSP, as shown in FIG. 24(a), Vl and Ml, v2 and M2, v3 and M 3 , .
.

In this way, the read signal input terminal of the light receiving section 501 and the read control line Mn of the analog memory 11502 are turned on sequentially one set at a time. Therefore, it is possible to sequentially store the video signal output from the light receiving section 501 in the analog memory section 502 for each line in the horizontal direction. In addition, if you want to store only the necessary video signals output from the light receiving section 501 in the analog memory section 502 for each line in the horizontal direction, the start pulse input from the VSP should be changed for two clocks. Instead of using a start pulse with a length of 1 clock,
It is sufficient to shift the number of locks by an appropriate number of locks and input two from the VSP. For example, as shown in FIG. 24(b), if two start pulses are shifted by 3 clocks and input from VSP, v2 and M1, V3 and M2, V4 and M3
・H is turned on one after another.

Configuring the V shift register in this way is very effective when capturing all the video signals in the area specified by the block, reducing the size of the electric circuit and memory and enabling high-speed processing. In addition, ① the control signal for operating the shift register can be simplified.

Next, a third embodiment of the focused point detection device according to the present invention will be described. In this embodiment, a so-called hill-climbing method is adopted as a method for detecting a focused point.

FIG. 25 is a block diagram schematically showing the configuration of a focused point detection device according to this embodiment. In the figure, 102 is a photographing lens, 202 is a photoelectric conversion device, and 205 is a filter circuit, respectively. 202 and has the same configuration as the filter circuit 205. Further, 2604 is a control circuit, 260
5 is an actuator. Note that the photoelectric conversion device 202
The V shift register may have a configuration as shown in the twelfth embodiment above.

In this configuration, the light beam from the subject is imaged by the photographing lens 102 on the light receiving surface of the photoelectric conversion device 202, and is photoelectrically converted. The output of the photoelectric conversion device 202 is extracted only at a specific frequency by a filter circuit 205.
It is input to control circuit 2604. The control circuit 2604 is
By driving the actuator 2605, the photographing lens 102
While moving the position of the photoelectric conversion device 202
The position of the photographing lens 102 where this output value is maximized is searched. That is, a focused state is obtained when the output value of the photoelectric conversion device 202 becomes maximum.

FIG. 26 shows the position of the photographing lens 102 and the photoelectric conversion device 2.
The relationship with the output value of 02 is shown. As shown in the figure, since the relationship between the two forms a smooth curve, the photoelectric conversion device 202
It is sufficient to move the photographing lens 102 in the direction in which the output value increases, and when the detected output value of the photoelectric conversion device 202 decreases, the photographing lens 102 is returned to the position that gives the previously detected maximum value.

When detecting a focused point using the method of this embodiment, only the output of the same pixel cell block of the photoelectric conversion device 202 is read out repeatedly, so ■ The shift register 503 is set with a predetermined scanning line turned on. It is fixed and only the H shift register 504 is operated to read out the video signal. In other words, (1) the shift register 503 is not reset, the receiving section 501, the analog memory section 502, and the H shift register 504 are reset, and the H shift register 503 is reset.
04 to read out the video signal.

As described above, according to the in-focus point detection device of this embodiment, (1) the shift register 503 is fixed in a predetermined state and the video signal can be read out by operating only the H shift register 504; It becomes possible to shorten the processing time until detection.

[Effects of the Invention] As explained in detail above, the present invention provides a focused point detection device that has a small electric circuit and memory and can speed up processing, that is, a low-cost and high-performance focusing point detection device. It is possible to provide a focused point detection device with high performance.

[Brief explanation of drawings]

FIG. 1 is a block diagram schematically showing the configuration of an electric circuit system of a single-lens reflex camera equipped with the in-focus point detection device of the present invention, and FIG. 2 is a block diagram of the configuration of the single-lens reflex camera shown in FIG. 1. FIG. 3 is a schematic diagram showing the configuration of the optical system of the single-lens reflex camera shown in FIG. 2. FIG. 5 is a block diagram schematically showing the internal configuration of the photoelectric conversion device 202, FIG. 6(a) is an electric circuit diagram showing the configuration of the pixel cell of the light receiving section, b) is a graph showing the photoelectric conversion characteristics of SiT, FIG. 7 is an electric circuit diagram showing the configuration of the analog memory section, FIG. 8(a) is a conceptual diagram showing the configuration of the V shift register, and FIG. 8(b) and FIG. 8(C) is a timing chart for explaining the operation of the V shift register.
Figure (a) is an electric circuit diagram showing the configuration of the basic block of the V shift register, Figure 9 (b) is a timing chart of the operation of the basic block of the V shift register, and Figure 10 is the H
Fig. 11 is a conceptual diagram showing the configuration of the shift register; Fig. 11 is a graph showing the relationship between the video signals of the subject image read out by the two blocks of the photoelectric conversion device; Fig. 12 is a graph for explaining the interpolation calculation; FIG. 13 is a conceptual diagram showing the configuration of the position detection circuit, FIG. 14(a) is an electric circuit diagram showing the configuration of the light receiving part that constitutes the line sensor, and FIG. 14(b) is a graph showing the photoelectric conversion characteristics of SiT. , Fig. 15 is a conceptual diagram showing how the distribution of light quantity reflected by the mirror and mask changes, Fig. 16 is an electrical circuit diagram showing the overall configuration of the line sensor, and Fig. 17 shows the operation sequence of the position detection circuit. 18 is a conceptual diagram showing changes in each output value of the light receiving section when the mirror and mask move, FIG. 19 is a schematic diagram of the configuration of the photographing lens, and FIG. 20 shows the subject for which focal point detection is performed. 21(a) and 21(b), which are conceptual diagrams for explaining the displacement of the position of the area, explain the state of the in-focus point when a predetermined lens group of the photographing lens is shifted from the in-focus position. 22 is a flowchart showing the operation sequence when detecting a focused point,
FIG. 23 is a conceptual diagram showing the configuration of the V shift register according to the embodiment of the present invention, FIG. 24 is a timing chart for explaining the operation of the V shift register shown in FIG. 23, and FIG. 25 is the invention of the present invention. FIG. 26 is a block diagram schematically showing the configuration of the in-focus point detection device according to the third embodiment, and FIG. 26 is a graph showing the relationship between the position of the photographing lens and the output value of the photoelectric conversion device. DESCRIPTION OF SYMBOLS 101...Focal point detection circuit, 102... Photographic lens, 103... Position detection circuit, 104... Drive control circuit, 201... AF optical system, 202... Photoelectric conversion device, 203... ...AF control circuit 203.204...Monitor circuit, 205...Filter circuit, 206...
Light emitting element, 207... Photoelectric conversion device, 501... Light receiving section, 502... Analog memory section, 503... V
Shift register, 504...H shift register, 50
5... Output circuit, 506... Control circuit Applicant's agent Patent attorney Jun Tsuboi Figure (a) Figure (b) Figure (a) Figure (b) ) MI M2 M3M4---V7 V7+1-Figure (b) Output reset start (a) Figure Figure 12 Figure 13 (a) I (b) Figure 14 element li leaf 1jl (a) ( b) (c) Figure 15 Figure 17 Figure 19 Figure 20 Figure 18 ■VFc+ (G 1: A-0,3mm) (a) (b) 1R21 Figure h4+ VI M2 V2 Figure 24 (a) M+ VI 2 V2 Figure 24 (b) Figure 25 Figure 26 Procedural Amendment 1995 2. Mulberry, -% Director General of the Patent Office Satoshi Uematsu 1, Indication of the case Patent Application No. 164562/1999 2o Name of the invention In-focus point detection device 3, Person making the correction Relationship to the case Patent applicant (037) Olympus Optical Industry Co., Ltd. 4, Agent: 3-7-2 Kasumigaseki, Chiyoda-ku, Tokyo 100 Telephone: 03 (502) 3181 (Main Representative) (6881) Patent Attorney: Jun Tsuboi 5, Contents of Voluntary Amendment 76 Amendment (1) Specification On page 2, lines 6 to 16, it says “Conventionally,
As a focused point detection device, for example, a device that detects two pupil-divided subject images using a photoelectric conversion device and obtains a focused point from a phase difference between the two detected subject images is known. Further, in such a focused point detection device, one using an area sensor as a photoelectric conversion device is known. In a focused point detection device that uses an area sensor as a photoelectric conversion device, usually only the video signal of a given region is extracted from the output (video signal) of each photoelectric conversion element that makes up the area sensor, and the focused point is detected by extracting only the video signal of an arbitrary region. used for detection. "Conventionally, as a focused point detection device, for example, two pupil-divided subject images are detected using a photoelectric conversion device having a line sensor, and the focused point is determined from the phase difference between the two detected subject images." There are known devices for obtaining
Distance measurement over a wide range is performed by combining the above-mentioned line sensors. Instead of using such a combination of the above-mentioned line sensors, an area sensor is used, and only the video signal of an arbitrary region is extracted from the output (video signal) of each photoelectric conversion element that makes up this area sensor, and the in-focus point is It may be used for detection. ” he corrected. (2) On page 21, lines 7 to 9 of the specification, it is stated that ``Standard value calculation is the calculation of the value (standard value) obtained by dividing the correlation calculation value obtained by the above correlation calculation by the contrast value. "The standard value calculation is a calculation to determine the reliability of the correlation calculation. Here, we calculate the value (standard value) divided by the correlation calculation value obtained by the above correlation calculation. I will do it by doing this.'' (3) In the 12th line of page 21 of the specification, the statement ``The vertical axis is the standard value of the correlation calculation value'' is corrected to ``The vertical axis is the correlation calculation value.'' (4) In the 13th line of page 21 of the specification, the statement "M indicates the point where the standard value is the minimum," is corrected to "M indicates the point where the correlation calculation value is the minimum." . (5) On page 21, line 16 of the specification, the phrase "the one with the larger standard value" is corrected to "the one with the larger correlation calculation value." (6) On page 21, line 17 of the specification, the phrase "the one with the smaller standard value" is corrected to "the one with the smaller phase open calculation value." (7) On page 34, line 5 of the specification, the phrase "r periodic pattern" is corrected to "aperiodic pattern." Atsushi Tsuboi, Patent Attorney, Applicant (Procedural Amendment Written Form) % Formula % On page 40, line 9 to line 10 of the statement of contents of the amendment

Claims (1)

[Scope of Claims] An imaging optical system that forms an image of a luminous flux from a subject, a photoelectric conversion means that photoelectrically converts the subject image formed by the imaging optical system, and a photoelectric conversion signal by the photoelectric conversion means. In the focused point detection device, the photoelectric conversion means includes a plurality of photoelectric conversion elements that output a photoelectric conversion signal for each pixel. , a plurality of analog memories that temporarily store outputs of the photoelectric conversion elements, and a shift register that reads out the photoelectric conversion elements and latches the read photoelectric conversion signals in the analog memory. A focused point detection device characterized by: