JPH1184226A - Focus position detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To respectively amplify output signals from respective photoelectric conversion element arrays on optimum conditions in a focus position detecting device including plural photoelectric conversion element arrays. SOLUTION: The output signals Vout from all the photoelectric conversion element arrays of a sensor 141 are temporarily amplified in a 1st amplification mode with the dark output voltage Vref of the photoelectric conversion element array as reference. The photoelectric conversion element array having the signal whose contrast arithmetically calculated by using the output signal from the photoelectric conversion element array amplified in the 1st amplification mode is smaller than a 1st compared value is driven again and the reoutput signal is reamplified in a 2nd amplification mode with voltage Vave in proportion to the average value of the output signal from the effective picture element of the photoelectric conversion element array with reference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focal position detecting device for optical equipment such as an autofocus camera, and more particularly to a focal position detecting device having two or more photoelectric conversion element arrays arranged in a horizontal direction and a vertical direction.

[0002]

2. Description of the Related Art In general, a phase difference detection method often used in single-lens reflex cameras and a passive method partially used in lens shutter cameras focus on a low-contrast target (subject). Position detection is difficult. Therefore, conventionally, the first method of amplifying the output signal of the photoelectric conversion element array with reference to the dark output voltage of each photoelectric conversion element array, or the average value voltage of the output signal from the effective pixel of the photoelectric conversion element array, A second method of amplification as a reference has been proposed. The second method is particularly effective when the target has high brightness and low contrast.

[0003]

When there is only one photoelectric conversion element array such as an early autofocus camera, etc., a method for amplifying an output signal from the photoelectric conversion element array is based on a method for amplifying the luminance of a target (subject). It is sufficient to select either the first method or the second method as a reference.

However, when focus position detection in a plurality of focus position detection areas is performed simultaneously using a plurality of photoelectric conversion element arrays, a low contrast target object and a high contrast target object are detected in the plurality of focus position detection areas. It may be mixed. In such a case, if the output signals from all of the photoelectric conversion element arrays are uniformly amplified by the first method, the amplified output signals for the high-contrast target may overflow the voltage level that can be handled by the CPU or the like. There is. Further, if the output signals from all the photoelectric conversion element arrays are uniformly amplified by the second method, even if the amplified output signals relating to the low-contrast target are not sufficiently contrasted, the focus position may not be detected. is there.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and includes a plurality of photoelectric conversion element arrays, and amplifies output signals from each photoelectric conversion element array under optimum conditions. It is an object of the present invention to provide a focus position detecting device.

[0006]

In order to achieve the above object, a focus position detecting apparatus according to the present invention includes a plurality of photoelectric conversion element arrays, and outputs an output signal of each photoelectric conversion element array to each of the photoelectric conversion element arrays. A first amplification mode in which amplification is performed on the basis of a dark output voltage, and a second amplification mode in which amplification is performed on the basis of a voltage equivalent to an average value of output signals from effective pixels of each photoelectric conversion element array. The contrast calculated using the output signal of each photoelectric conversion element array amplified in the amplification mode is compared with a first comparison value. If the contrast is smaller than the first comparison value, the photoelectric conversion element array is compared with the first comparison value. And outputs the re-output signal to the second
Reamplify in the amplification mode.

According to the above configuration, the output signals of all the photoelectric conversion element arrays are once amplified in the first amplification mode in which the output signals are amplified based on the dark output voltage of the photoelectric conversion element arrays, and the amplified output signals are used. The amplification mode is changed again for the computed contrast lower than the first comparison value and amplification is performed, so that the outputs from all the photoelectric conversion element arrays are amplified in the most suitable amplification mode. The “voltage according to the average value of the output signal from the effective pixel” in the second amplification mode is as follows.
Not only the average voltage of the output signal from the effective pixel but also a constant reference voltage approximating this may be used.

In the above configuration, one of the contrasts is one.
If at least one is smaller than the first comparison value, the contrast is compared with the second comparison value, and if the contrast is larger than the second comparison value, the first gain is set, and the contrast is set to the second comparison value. If the second gain is smaller than the first gain, the second gain is set larger than the first gain.
It is preferable to perform re-amplification in the second amplification mode using the gain of (1). With this configuration, amplification in the second amplification mode is performed with an optimal gain according to the level of the output signal of the photoelectric conversion element array.

In the above structure, any one of the plurality of photoelectric conversion element arrays may be a second photoelectric conversion element array.
When the signal is re-amplified in the amplification mode, the output signal of the photoelectric conversion element array is amplified in the second amplification mode from the next time,
The contrast calculated using the output signal of the photoelectric conversion element array amplified in the second amplification mode is compared with a third comparison value, and when the contrast is larger than the third comparison value,
It is preferable to drive the photoelectric conversion element array and re-amplify the re-output signal in the first amplification mode. According to this configuration, for the output signal from the photoelectric conversion element array once set to be amplified in the second amplification mode, it is checked whether or not overflow occurs due to lack of gain from the next amplification. If it does overflow, it is returned to the normal first amplification mode.

Alternatively, in the above configuration, when one of the plurality of photoelectric conversion element arrays is re-amplified in the second amplification mode, the output signal of the photoelectric conversion element array is output to the second amplification mode from the next time. The contrast calculated using the output signal of the photoelectric conversion element array amplified in the amplification mode of
If the contrast is larger than the third comparison value, it is determined whether the gain when the signal is re-amplified in the second amplification mode is the first gain or the second gain. When the gain is the gain, the photoelectric conversion element array is driven, and the re-output signal is re-amplified in the second amplification mode using the first gain. When the gain is the first gain, the photoelectric conversion element array is It is preferable to drive and re-amplify the re-output signal in the first amplification mode. According to this configuration, the second
If the amplified output signal overflows as a result of the amplification in the amplification mode, the gain in the second amplification mode is reduced as the first step, and if the overflow still occurs, the second step is the first amplification mode. Will be returned.

In each of the above structures, the plurality of photoelectric conversion element arrays are divided into a plurality of focus position detection areas, and the output signals of the photoelectric conversion element arrays included in the focus position detection areas are used for each of the focus position detection areas. Are compared with the first comparison value, and when all the contrasts of the same focus position detection area are smaller than the first comparison value, all the photoelectric conversion element arrays of the focus position detection area are compared. It is preferable to drive and re-amplify the re-output signal in the second amplification mode. According to such a configuration, one focus position is detected not for each photoelectric conversion element array but for each focus position detection area, and it is possible to reduce the number of signal processing such as calculation of the defocus amount thereafter. The time required for focus position detection can be shortened.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a focus detection device according to the present invention will be described with reference to the drawings. FIG. 1 shows a configuration example of a so-called AF single-lens reflex camera in which a lens body 200 can be separated from a camera body 100.

The optical axis L is located substantially at the center of the camera body 100.
Main mirror 111 and main mirror 1 inclined approximately 45 degrees with respect to
A mirror box 110 is provided on the back surface of the mirror 11 and has a main mirror provided with an auxiliary mirror 112 and the like inclined at an angle of about 90 degrees with respect to the inclination of the mirror 111. Mirror box 1
A finder 120 including a reticle 121, a prism 122, an eyepiece 123, a display element 124, and the like is provided on an upper part of the apparatus 10. A light emitting unit 1 for emitting a flash light is provided above the finder 120.
70 are provided.

At the bottom of mirror box 110 (the side opposite to finder 120), AF sensor module 14
0, a light control sensor 150, an AF drive unit 160, and the like. A shutter unit 130 is provided between the rear surface of the mirror box 110 (the side opposite to the lens body 200) and the film surface 1. AFCPU3
The flexible printed circuit board 300 provided with the wires 01 and the wiring 302 is provided in a gap between the camera body 100.

The lens body 200 includes an optical system 201, a lens barrel 202 holding the optical system 201, a lens driving mechanism 203 for driving the lens barrel 202 in a direction A parallel to the optical axis L, a focal length of the lens, and an open F value. , Minimum F-number, etc., and outputs the same to the AFCPU 301 on the camera body side.
Etc. are provided.

The main mirror 111 reflects most of the light beam from the optical system 201 in the direction of the reticle 121 and transmits the remaining part. The auxiliary mirror 112 guides the light beam transmitted through the main mirror 111 to the AF sensor module 140. The prism 122 reverses the left and right of the image on the focusing screen 121 and guides the image to the photographer's eye via the eyepiece lens 123.

A photometric unit 180 is provided near the exit surface of the prism 122. Photometric unit 180
Includes a condenser lens and a photoelectric conversion element such as a photodiode, and outputs a signal corresponding to the luminance of the subject 2 to the AFCPU 3.
Output to 01. The display element 124 includes a light-emitting element such as a light-emitting diode, a liquid crystal display element, and the like, and displays a state in which the lens is focused on the subject 2 (focused state), a shutter speed, an aperture value of the lens, and the like.

The light-emitting unit 170 includes a capacitor (not shown) for storing light-emitting energy, a charging circuit (not shown) for charging the capacitor, and discharges electric energy stored in the capacitor to light energy. An arc tube 171 for conversion, a reflector 172 for reflecting flash light from the arc tube 171 forward of the camera, and a Fresnel lens 17 for condensing or diffusing the flash light in a predetermined range.
3 and so on. The light control sensor 150 includes, for example, a condensing lens and a photoelectric conversion element such as a photodiode, detects reflected light from the film 1 during emission of flash light by the light emitting unit 170, and outputs a signal corresponding to the light amount to the AFCPU 301. Output to When the AF CPU 301 determines that the exposure amount of the film 1 has reached a predetermined value based on a signal from the light control sensor 150, the light emitting unit 17
Light emission of 0 is stopped.

The AF drive unit 160 includes an actuator such as a DC motor, a stepping motor, and an ultrasonic motor, an encoder that detects the rotation direction and the number of rotations of the actuator and outputs the detected signal to the AF CPU 301, and a deceleration for reducing the number of rotations of the actuator. It includes a system (not shown) and is connected to the lens driving mechanism 203 via the output shaft 161. The lens driving mechanism 203 is composed of, for example, a helicoid and a gear (not shown) for rotating the helicoid, and integrally drives the optical system 201 and the lens barrel 202 in the direction of arrow A by the driving force of the actuator of the AF driving unit 160. Move. Optical system 201 and lens barrel 202
The movement direction and the movement amount of the actuator follow the rotation direction and the rotation speed of the actuator, respectively.

FIG. 2 shows the details of the AF sensor module 140.
Shown in The AF sensor module 140 includes a plurality of CCDs.
, A sensor 141 having a photoelectric conversion element array, and four pairs of lenses provided in front of the sensor 141 (closer to the optical system 201) and corresponding to a reference portion and a reference portion (described later) of each photoelectric conversion element array. A separator lens 142 having
An aperture mask 143 having an opening corresponding to each lens, a mirror 144 for bending an optical path in a predetermined direction, and a mirror 14
The condenser lens 145 includes a condenser lens 145 provided in front of the aperture mask 143 with respect to the aperture mask 4, and a field mask 146 provided in front of the condenser lens 145 and having an opening having a shape corresponding to each photoelectric conversion element array.

The incident surface of the sensor 141 is located at the focal plane of the separator lens 142. The separator lens 142 splits the incident light beam and projects it on each photoelectric conversion element array.
Each opening of the aperture mask 143 has a circular shape or an oval shape, and limits a light beam incident on the separator lens 142. The field mask 146 is provided near a position where the distance from the optical system 201 is relatively equal to that of the film 1, and restricts a light beam incident on the AF sensor module 140 among light beams from the optical system 201. The openings of the field mask 146 correspond to the arrangement of the photoelectric conversion element arrays of the sensor 141. For example, the center opening is a cross shape, and the openings on both sides are rectangular.

FIG. 3 shows the photoelectric conversion element array of the sensor 141.
Shown in In the figure, the photoelectric conversion element array 41 arranged in the vertical direction on the left side is referred to as a first island, and the upper half is a reference portion 41a and the lower half is a reference portion 41b. The photoelectric conversion element array 42 arranged in the horizontal direction at the center is referred to as a second island, and the left half is a reference part 42a and the right half is a reference part 42b. The photoelectric conversion element array 43 arranged in the vertical direction on the right side is referred to as a third island, and the upper half is a reference portion 43a,
The lower half is referred to as a reference section 43b. The photoelectric conversion element array 44 vertically arranged at the center is referred to as a fourth island, and the upper half is referred to as a reference part 44a and the lower half is referred to as a reference part 44b.
The first island 41 and the third island 43 independently constitute first and third areas, respectively. Further, the second island 42 and the fourth island 44 are connected to the sensor 141.
Constitutes a second area at the center of. In the present embodiment, the reference portions 41a to 44 of the first to fourth islands 41 to 44 are used.
The number of pixels of “a” is the same as the number of pixels of each of the reference units 41b to 44b.

The pixel data of each of the reference portions 41a to 44a of the first to fourth islands 41 to 44 is divided into a plurality of blocks S1 to S9, respectively.
The focal position of the optical system 201 is detected by comparison with the data of b to 44b. Reference part 4 of the second island 42
The correlation calculation for detecting the focus position of the optical system 201 will be described with reference to FIG.

In the correlation operation in this embodiment, a first operation mode for comparing pixel data near the right end of the S3 block with pixel data near the left end of the reference section 42b,
A second operation mode for comparing all the pixel data of the three blocks with all the pixel data of the reference unit 42b, and a third operation for comparing the pixel data near the left end of the S3 block with the pixel data near the right end of the reference unit 42b. Modes can be distinguished. Note that the first to third calculation modes correspond to the first to fourth calculation modes.
It can be applied to all the blocks S1 to S9 of the islands 41 to 44.

In FIG. 4, the pixel data of the S3 block is referred to as b (1), b (2),.
Assume that the pixel data of b is r (1), r (2),... r (T) in order from the left. Note that the number of pixels of the S3 block N = 26,
2b total pixel number T = 56, left offset amount M = 15,
Right offset amount L = 15, correlation calculation rank k (k = 0 to (M + T
-N + L = 60)), the correction coefficient is R (k), and the amount of mismatch by the k-th correlation operation on the n-th island is Hn (k).

In the first operation mode, first, M (M = 15) pixels are offset from the left side of the pixel data of the S3 block, and 11 pixel data b (16) to b (16) to
b (26) and 11 pixel data r (1) to r (r) of the reference section 42b
The mismatch amount H2 (0) is calculated using (11). Next, S3
The pixel data of the block is shifted right by one, and the twelve pixel data b (15) to b (26) of the S3 block and the reference unit 42b
Using the twelve pixel data r (1) to r (12), the mismatch amount H2 (1) is calculated. Pixel data is increased one by one in order, and fifteen mismatch amounts H2 (k) (k = 0 to 14) are calculated.
Disagreement amount Hn (k) in the first calculation mode (k = 0 to (M-1))
Is the following equation (1).

[0027]

(Equation 1)

In the second operation mode, since all the pixel data of the S3 block and all the pixel data of the reference section 42b are compared, the first mismatch H2 (15) in the second operation mode is S3
The calculation is performed using the 26 pixel data b (1) to b (26) of the block and the 26 pixel data r (1) to r (26) of the reference unit 42b. The second non-coincidence amount H2 (16) is based on the 26 pixel data b (1) to b (26) of the S3 block and the reference unit 42b.
Is calculated using the 26 pixel data r (2) to r (27). Similarly, 31 H2 (k) (k = 15 to 45) are calculated. The discrepancy amount Hn (k) (k = M to (M +
The general formula of TN-1)) is the following formula (2).

[0029]

(Equation 2)

In the third operation mode, first, the right one of the pixel data of the S3 block is offset, and
The mismatch amount H2 (46) is calculated using the 25 pixel data b (1) to b (25) of the block and the 25 pixel data r (31) to r (56) of the reference unit 42b. Next, the pixel data of the S3 block is shifted right by one, and the 24 pixel data b (1) to b (24) of the S3 block and the 24 pixel data r (32) to r (r) of the reference unit 42b are shifted. The mismatch amount H2 (47) is calculated using 56). The pixel data is reduced one by one in order, and 15 mismatch amounts H2 (k) (k = 46 to 60) are calculated. The general expression of the mismatch amount Hn (k) (k = (M + TN) to (M + T−N + L)) in the third calculation mode is as follows:

[0031]

(Equation 3)

Here, regarding the amount of mismatch Hn (k), the second
This will be described with reference to FIG. 5 showing an example of the calculation mode. 5A to 5C, the curve B represents data b (1) to b (j) from each pixel of the reference portion 42a of the second island 42.
Are connected by a curve, and the curve R is the second island 4
The data r (1) to r (j) from each pixel of the second reference section 42b are connected by a curve.

In (a), the pixel data b of the S3 block
(1) to b (j) are compared with the pixel data r (1) to r (j) of the reference section 42b, and the area of the portion surrounded by the curve B and the curve R indicated by oblique lines in the drawing is Initial mismatch amount H2 in 2-operation mode
(15) (General formula: Hn (M)).

In (b), the pixel data b of the S3 block
(1) to b (j-2) and pixel data r (3) to r (j) of the reference unit 42b
In the figure, the area of the portion surrounded by the curves B and R indicated by the oblique lines is the third mismatch amount H2 (17) in the second calculation mode (general formula: Hn (M + 2) ). Compared with (a), the curve B and the curve R are close to each other,
And the area surrounded by the curve R is small.

In (c), the pixel data b of the S3 block
(1) to b (j-3) and pixel data r (4) to r (j) of the reference unit 42b
In the figure, the area of the part surrounded by the curves B and R indicated by the oblique lines is the fourth mismatch amount H2 (18) in the second calculation mode (general formula: Hn (M + 3) ). Since the curve B and the curve R substantially coincide with each other, the area surrounded by the curve B and the curve R is substantially zero.

All blocks S3 of the second island 42
ＳS5, the mismatch amount Hn (k) (k = 0〜 (M + T−
N + L)), the position where the value of the mismatch Hn (k) is the smallest is determined as the focal position of the optical system 201. In this case, the mismatch amount H2 (18) (general formula: H
Since n (M + 3)) is the smallest, this position is determined to be the focus position.

Incidentally, the example shown in FIG. 5 is an ideal case, and even when the optical system 201 is actually focused, the mismatch amount does not always become zero. Further, even under the same condition, the value of the mismatch amount Hn (k) differs depending on the number of pixels used for the correlation calculation. In particular, in the first operation mode and the third operation mode, since the number of pixels used for the correlation operation changes, it is not possible to simply compare the mismatch amount Hn (k) even in the same operation mode. Therefore, the correction coefficient R
Use (k). As the correction coefficient R (k), for example, a method of normalizing by the ratio of the contrast of the pixels used for the correlation calculation (for example, the sum of the absolute values of the differences between the outputs of the data from two adjacent pixels) or the correlation calculation A method of normalizing based on the ratio of pixels to be used may be considered.

As shown in FIG. 6 (a) or (b), when the position m0 where the mismatch Hn (k) is the minimum is located between the pixel m and the pixel m + 1 or m-1, the following is obtained. Equation (4)
Performs a complement operation according to. Since this complementary operation is known, its description is omitted.

[0039]

(Equation 4)

In the example shown in FIG. 5, the displacement of the pixel data between the reference portion 42a and the reference portion 42b in the second island 42 is three pixels in the right direction. The AF sensor module 140 substantially detects the direction and amount of displacement between the image position of the subject 2 by the optical system 201 and the film surface 1. By the way, the defocus amount of the optical system 201 and the moving amount of the image position have a fixed relationship depending on the focal length of the optical system 201. Therefore, the defocus amount (movement amount) of the optical system 201 is calculated using a shift amount of the pixel data, a coefficient based on the focal length of the lens, and the like. The optical system 20
The moving direction of 1 is determined by the direction of the shift of the pixel data.

Next, FIG. 7 shows a block configuration of the connection relationship between the AF CPU 301 and the AF sensor module 140. In the AF sensor module 140, in addition to the configuration shown in FIG. 2, based on signals from the clock generation unit 150 for driving the sensor 141 and the signal from the AF CPU 301, charge accumulation (hereinafter, referred to as each of the islands 41 to 44 of the sensor 141). , Integration)) CCD operation control unit 151 and sensor 14 for controlling the start and the start of reading of the accumulated electric charge.
1 from each of the islands 41 to 44 (Vou
An integration time control unit 152 for controlling the charge accumulation time (integration time) based on t), and an analog signal processing unit 153 for amplifying output signals (Vout) from the islands 41 to 44 of the sensor 141 are provided. I do. The integration time control unit 152 shortens the integration time when the brightness of the subject 2 is high, and increases the integration time when the brightness of the subject 2 is low,
The time is adjusted from each of the islands 41-44.

The AF CPU 301 converts an analog output signal (Vamp) from the analog signal processing unit 153 into a digital signal into an A / D conversion unit 310, an A / D converted digital signal, and a focus of the optical system 201 from the lens CPU 204. A storage unit 311 such as a RAM for storing distance information and the like, and an optical system 2 based on the A / D converted signal
01 for detecting the focal position of the optical system 201, the focal position of the optical system 201, the focal length of the optical system 201, and the like, which are detected by the focus detector 312. ), And
For example, a correction operation unit 313 that outputs a focus signal to the display element when the focus of the optical system 201 is on the subject 2 or the like,
Lens drive control unit 3 that drives AF drive unit 160 and lens drive mechanism 203 based on the calculated correction amount
14. Output a predetermined clock pulse (CP) to the clock generation unit 150, output a charge accumulation start (integration start) signal (ICG) and a charge readout start signal (SHM) to the operation control unit 151, and Mode switching signal (MD) for switching the amplification mode to 153
Control section 315 for outputting the image signal, lens drive control section 31
4 and a timer circuit 316 that outputs a predetermined timing signal to the sensor control unit 315.

Next, the islands 41 to 41 of the sensor 141
The amplification mode of the output signal 44 will be described with reference to FIGS. Generally, when the subject 2 has a low contrast, the change of the output signal (Vout) of each of the islands 41 to 44 of the sensor 141 is small. Therefore, it is difficult to determine the focal position of the optical system 201 using these signals as they are. Therefore, in order to obtain a change in the output signal enough to determine the focal position of the optical system 201, the output signal (Vo) of each of the islands 41 to 44 of the sensor 141 is obtained.
ut).

As a normal amplification mode, a mode in which amplification is performed based on a dark output voltage of the sensor 141 (hereinafter, referred to as an NM mode) is known. The NM mode is effective for a subject having low luminance and low contrast. FIG. 8 shows an example of amplification in the NM mode. (A) is an output signal (Vout) and dark output voltage (Vref) of one of the islands 41 to 44 of the sensor 141 before amplification.
(B) shows the amplified output signal (Vamp) and the amplified dark output voltage (Vref2).

On the other hand, if the output signal (Vout) of each of the islands 41 to 44 is amplified based on the dark output voltage (Vref) when the subject 2 has a high luminance and a low contrast, the voltage exceeds the voltage that can be handled by the AF CPU 301 or the like. (So-called overflow). Therefore, it has been proposed to use a mode of amplifying based on the average voltage of the effective pixel output (hereinafter referred to as LC mode). FIG. 9 shows an example of amplification in the LC mode. (A) is an island 41 of the sensor 141 before amplification.
To 44, the average value (Vave) of the effective pixel output voltages, and the dark output voltage (Vre).
(b) shows the output signal (Vamp) after amplification, the average value (Vave) of the non-amplified effective pixel output voltage, and the dark output voltage (Vref).

FIGS. 10 and 11 show examples of the circuit configuration of the analog signal processing section 153. FIG. In the configuration example illustrated in FIG. 10, an output signal (Vout) of any one of the islands 41 to 44 of the sensor 141 is input to the + input terminal of the OP amplifier 1531. The output Vout2 before amplification of the OP amplifier 1531 is input to the average value calculation circuit 1532, and the average value (Vave) of the effective pixel output voltage is calculated. The calculated average value (Vave) of the output voltage is input to the average value holding circuit 1533, and the voltage is held. OP
The switch 1535 is connected to the negative input terminal of the amplifier 1531. One of the dark output voltage (Vref) from the dark output voltage circuit 1534 and the average value (Vave) of the output voltage of the average value holding circuit 1533 is determined by the two. Entered alternatively. When the switch 1535 selects the output voltage (Vref) of the dark output voltage circuit 1534, N as shown in FIG.
Amplification based on the dark output voltage in the M mode is performed. When the switch 1535 selects the average value (Vave) of the output voltage of the average value holding circuit 1533, amplification based on the average value of the effective pixel output voltage in the LC mode as shown in FIG. 9 is performed.

In the case of amplification in the LC mode, the reference voltage input to the minus input terminal of the OP amplifier 1531 does not necessarily need to be the average value of the effective pixel output voltage, but may be any voltage approximate to this value. good. In the configuration example illustrated in FIG. 11, a monitor voltage (Vmon) that is close to the average value (Vave) of the output voltage from the monitor voltage circuit 1536 is used instead of the average value (Vave) of the effective pixel output voltage. With this configuration, it is not necessary to calculate the average value (Vave) of the effective pixel output voltage from the output of the OP amplifier 1531, so that the circuit configuration is simplified and the time required for the calculation processing is reduced.

Next, the operation of this embodiment will be described with reference to FIG.
This will be described with reference to flowcharts shown in FIGS.

When a power switch (not shown) of the camera body 100 is turned on (# 1), the AF CPU 301 resets all the setting states and sets the amplification mode to NM (# 3). Next, the AF CPU 301 determines whether or not a switch S1 (not shown) that is turned on when the shutter release button is in a so-called half-pressed state is turned on (#
5). When the switch S1 is ON, the AFCPU 301 starts detecting the focal position of the optical system 201 because the user has put his finger on the shutter release button and is in the shooting state.

The AF CPU 301 sets a first counter (m = 1) to count the number of integrations m of the sensor 141 (# 7).
5 and the like, and the first to fourth islands 4 of the sensor 141 are controlled.
The integration of 1 to 44 is performed (# 9). In parallel with this,
A second counter (n = 1) to transfer the data of the fourth to fourth islands 41 to 44 to the analog signal processing unit 153 and the like.
Is set (# 11). Here, an island for transferring the output signal is an n-th island (n = 1 to 4).

Next, it is determined whether or not the count value m of the first counter is 1 (# 13). When the first integration of the sensor 141 is performed, that is, when m = 1, the AFCPU 301 transfers the output signal of the n-th island (# 15). After the transfer of the output signal of the n-th island is completed, the count value of the second counter is set to 1
Next (# 17), it is determined whether or not data up to the last fourth island 44 of all islands has been transferred, that is, whether or not the count value n of the second counter is 5 (# 19). n
If not, the process returns to # 13.

On the other hand, if m = 1 is not satisfied in # 13,
The AF CPU 301 determines whether the count value m of the first counter is 3 (# 14). If m = 3, the sensor 141
In the second integration, the contrast is low and the focus position cannot be detected.
A low contrast display is performed on 24 (# 16).

When m = 3 is not satisfied in # 14, that is, when the second integration of the sensor 141 is performed, the first to fourth integrations are performed.
Since the request is a retransfer request of the output signal of any of the islands, the AFCPU 301
It is determined whether the retransfer flag is on (# 2)
1). If the retransfer flag is on, the output signal of the nth island is transferred (# 15). If the retransfer flag is not on, the count value of the second counter is increased by one (# 17), and the same operation is performed for the next island.

Next, the AF CPU 301 amplifies the output signal of the n-th island output signal sequentially transferred by the analog signal processing unit 153.
At this time, it is determined whether or not LC mode amplification is designated as the amplification method for the n-th island (# 23). First
When the count value m of the counter is 1, it is the first integration of the sensor 141, and since the setting state has been reset in # 3, the analog signal processing unit 153 amplifies the output signal in the NM mode (# 25). . On the other hand, when it is determined in # 23 that the LC mode is specified as the amplification method, the analog signal processing unit 153 amplifies the output signal in the LC mode (# 27). The amplified output signal is A
A / D conversion is performed by the / D conversion unit 310 (# 29).
The / D-converted data is stored in the storage unit 311 (#
31).

Next, the AF CPU 301 sets a third counter (n = 1) to calculate the contrast for each of the first to fourth islands 41 to 44 (# 33). A
The FCPU 301 calculates the contrast sequentially from the first island 41 using the data stored in the storage unit 310 (# 35). Also in this case, the island for which the contrast calculation is performed is referred to as an n-th island (n = 1 to 4), and the calculated contrast is referred to as CAn.

The AF CPU 301 determines whether or not the n-th island was previously amplified in the LC mode (# 37). In the case of the first integration of the sensor 141, since the output signal of each island is amplified in the NM mode,
At # 37, the determination is NO, and the AF CPU 301 compares the calculated contrast CAn of the n-th island with the first comparison value C1.
(# 39). If CAn> C1, the contrast CAn of the nth island is compared with a second comparison value C2 smaller than C1 (# 41).

In # 41, CAn> C2, that is, C
When 1 ≧ CAn> C2, the gain when amplifying the output signal of the n-th island in the LC mode is set to twice (× 2) (# 43). On the other hand, in # 43, CAn> C2
In other words, when C2 ≧ CAn, the contrast is even lower, so the gain for amplifying the output signal of the n-th island in the LC mode is set to four times (× 4) (# 45). In either case, the retransmission flag of the n-th island determined in # 21 is turned on to re-transmit the output signal of the n-th island in # 15 (# 47).

If it is determined in step # 37 that the amplification was performed in the LC mode last time, the contrast CAn of the n-th island is calculated using the output signal of the sensor 141 obtained by the integration after the second integration in the LC mode. Therefore, the value of the contrast CAn is originally high. Therefore, the contrast CAn of the n-th island is compared with a third comparison value C3 that is larger than C1 (# 49). Here, C3>C1> C2.

If CAn> C3 in # 49, since the contrast CAn is too high and is not suitable for subsequent focus position detection, the amplification method of the n-th island is re-designated to the NM mode (# 51), and the NM mode is set. The retransmission flag of the n-th island is turned on to retransmit the amplified output signal (# 47).

If CAn> C1 in # 39 and #
In the case where CAn> C3 is not satisfied, the calculated contrast of the n-th island is proper, so that the count value of the third counter is advanced by one to process the next island (# 53), and the last fourth island is processed. It is determined whether or not the contrast of No. 44 has been compared with predetermined comparison values C1 to C3, ie, whether or not the count value n of the third counter is n = 5 (# 5).
5). If n <5, the process returns to # 35, calculates the contrast of the next island, and performs the same comparison (# 35 to # 35).
3).

When the contrast calculation and comparison are completed for all of the first to fourth islands 41 to 44 (#
(YES at 55), AFCPU 301 determines whether or not the retransfer flag is on for any of the islands (# 57). If the retransfer flag is turned on for any of the islands, it is requested to retransfer the output signal for that island.
1 advances the count value m of the first counter by one (# 59);
The flow from # 9 to # 57 is performed again.

If the retransfer flag is not on for any of the islands (NO in # 57), the first to fourth
For all of the islands 41 to 44, the contrast C
An indicates that An is in an appropriate range of C3>CAn> C2 (n = 1 to 4). Therefore, the AFCPU 301
Starts the focus position detection of the optical system 201 using the data stored in the storage unit 311 (# 61).

When the focus position detection is started, the AF CPU 3
01 sets a counter n and inputs n = 1 (# 6
3). For the n-th island, calculation data such as the number N of pixels in each block of the reference portion, the total number T of pixels in the reference portion, the vertical and horizontal offset amounts L and M, and the correction coefficient R (k) are set (# 65). ). Further, the AF CPU 301 uses the pixel data of the reference portion and the pixel data of the reference portion of the n-th island read from the storage portion 311 to calculate the total according to the expressions (1) to (3) regarding the first to third calculation modes. The (M + T−N + L + 1) mismatch amounts Hn (k) are calculated (# 67). When the total amount of mismatch Hn (k) is calculated, the respective amounts of mismatch Hn (k) are compared, and the position where the amount of mismatch Hn (k) becomes the smallest, that is, the focus position is determined (# 6).
9). If a complement operation is required, the complement operation is performed according to the above equation (4). When the focal position is determined, the moving amount of the optical system 201, that is, the defocus amount is calculated based on the data (# 71). The calculated defocus amount is temporarily stored in the storage unit 311. After calculating the defocus amount, the AF CPU 301 increments the counter n by one (# 73), and determines whether the defocus amount has been calculated for all of the islands 41 to 44 (# 7).
5). If n = 5, the flow returns to # 65, and the defocus amounts of all the islands are calculated.

When the defocus amounts are calculated for all the islands 41 to 44, the AF CPU 301 determines an algorithm for determining one defocus amount for actually controlling the movement of the optical system 201 from among the plurality of defocus amounts. It starts (# 77). First, the defocus amount DF2 of the second island 42 and the defocus amount D of the fourth island 44 arranged in a substantially cross shape at the center of the sensor 141 are described.
In order to select any one of F4, these defocus amounts DF2 and DF4 are read from the storage unit 311 (# 79).

Next, the AF CPU 301 determines whether the defocus amount DF2 of the second island 42 is sufficiently larger than the defocus amount DF4 of the fourth island 44 (# 81). The determination as to whether it is “sufficiently” is made by, for example, determining the defocus amount DF2 of the second
This is performed by comparing the absolute value of the difference between the defocus amounts DF4 of the islands 44 and a comparative value of a predetermined large value.
The predetermined comparison value is set experimentally and empirically. The defocus amount DF2 of the second island 42 is the fourth island 4
4 is sufficiently larger than the defocus amount DF4 (##
81), the AF CPU 301 determines that the second island 4
The defocus amount DF2 of No. 2 is selected as the defocus amount from the second area (# 91).

The defocus amount DF of the second island 42
2 is smaller than the defocus amount DF4 of the fourth island 44 and the defocus amount D of the second island 42
When F2 is larger than the defocus amount DF4 of the fourth island 44, but both are relatively close (NO in # 81), the AF CPU 301 determines that the defocus amount DF4 of the fourth island 44 is It is determined whether or not it is sufficiently larger than the defocus amount DF2 (# 8)
3). The determination as to whether it is “sufficiently” large is the same as in the case of # 81. Defocus amount D of fourth island 44
If F4 is sufficiently larger than the defocus amount DF2 of the second island 42 (YES in # 83), the AFCPU 3
01 selects the defocus amount DF4 of the fourth island 44 as the defocus amount from the second area (# 8)
9).

The defocus amount DF of the fourth island 44
4 is smaller than the defocus amount DF2 of the second island 42 and both are relatively similar, and the defocus amount DF4 of the fourth island 44 is larger than the defocus amount DF2 of the second island 42, If both are relatively close (NO in # 83), AFCPU3
01 determines whether the value RE2 indicating the reliability of the second island 42 is larger than a predetermined value Y1 (# 85).
Here, as the value RE2 indicating the reliability of the second island 42, the minimum mismatch amount H for the second island 42
2 (k) and contrast CA2 are used. The same applies to the following cases. Value DF indicating reliability of second island 42
If 2 is larger than predetermined value Y1 (YES in # 83),
The AF CPU 301 selects the defocus amount DF2 of the second island 42 as the defocus amount from the second area (# 91). In # 85, the defocus amount DF2 of the second islands 42 arranged in the horizontal direction is replaced by the defocus amount DF of the fourth islands 44 arranged in the vertical direction.
4 is preferentially selected.

A value RE indicating the reliability of the second island 42
2 is not larger than the predetermined value Y1 (# 85
O), the AF CPU 301 determines whether or not the value RE2 indicating the reliability of the second island 42 is larger than the value RE4 indicating the reliability of the fourth island 44 (# 87). When the value RE2 indicating the reliability of the second island 42 is larger than the value RE4 indicating the reliability of the fourth island 44 (#
87 is YES), the AF CPU 301 determines that the second island 4
The defocus amount DF2 of No. 2 is selected as the defocus amount from the second area (# 91). On the other hand, when the value RE4 indicating the reliability of the fourth island 44 is larger than the value RE2 indicating the reliability of the second island 42 (N in # 87)
O), the AF CPU 301 selects the defocus amount DF4 of the fourth island 44 as the defocus amount from the second area (# 89).

When the defocus amount from the second area is selected, the AF CPU 301 sets the defocus amount D of the first island 41 as the defocus amount from the first area.
F1 is the defocus amount from the third area, and the defocus amount DF3 of the third island 43 is stored in the storage unit 311.
(# 93), and the position of the defocus amount in the first to third areas, for example, the defocus amount from the region indicating the subject closest to the camera is determined as the final defocus amount (# 95). When the final defocus amount is determined, the AF CPU 301 calculates a correction amount of the focal position of the optical system 201 based on the final defocus amount, and drives the AF driving unit 160 and the lens driving mechanism 203 based on the calculated correction amount. (# 97).

In the flowcharts shown in FIGS.
In 57, when the re-transfer flag is turned on for any of the islands, the process returns to # 9 and the re-integration is performed for all of the first to fourth islands 41 to 44 of the sensor 141. The present invention is not limited to this. If the integration can be controlled for each of the first to fourth islands 41 to 44, re-integration may be performed only for the island whose re-transfer flag is on.
Further, in # 23 to # 27, each of the output signals of the first to fourth islands 41 to 44 is configured to determine whether the mode is the LC mode or the NM mode and to independently amplify the output signal. All of the islands 41 to 44 may be amplified in the LC mode or the NM mode, and only the amplified output signal relating to the island for which retransmission is requested may be transferred to the A / D converter 310 or the like.

Also, in the above embodiment, # 35 to # 57
In the above, the contrast is calculated for each of the first to fourth islands 41 to 44, and the amplification mode, the gain, and the like are set. However, the contrast, the amplification mode, the gain, and the like may be set for each area. Since the first and third areas substantially coincide with the first and third islands 41 and 43, specifically, which of the second and fourth islands 42 and 44 has a higher contrast with respect to the second area. And the subsequent calculation is performed only on the data of the selected island. In this case, the defocus amount determination routine for the second area from # 77 to # 91 becomes unnecessary.

[0072]

As is clear from the above description, the focal position detecting device of the present invention includes a plurality of photoelectric conversion element arrays, and outputs the output signal of each photoelectric conversion element array to the darkness of each photoelectric conversion element array. A first amplification mode in which amplification is performed with reference to an output voltage, and a second amplification mode in which amplification is performed with reference to a voltage equivalent to an average value of output signals from effective pixels of each photoelectric conversion element array.
The contrast calculated using the output signal of each photoelectric conversion element array amplified in the first amplification mode is compared with a first comparison value, and the contrast is higher than the first comparison value. For small ones, the photoelectric conversion element array is driven and the re-output signal is re-amplified in the second amplification mode. Amplification is performed in the first amplification mode in which amplification is performed as a reference, and a contrast lower than a predetermined first comparison value among contrasts calculated using the amplified output signal is changed again in the amplification mode to perform amplification. The output from the photoelectric conversion element array can be amplified in the most suitable amplification mode. As a result, it is possible to perform focus position detection based on a signal having a high contrast suitable for focus position detection that has been optimally amplified, and it is possible to increase the focus position detection accuracy.

Further, the contrast is compared with the second comparison value. If the contrast is larger than the second comparison value, the first gain is set. If the contrast is smaller than the second comparison value, the first gain is set. Is set in the second amplification mode using the set first or second gain, and the optimum gain according to the contrast of the target object is obtained. , The amplification in the second amplification mode can be performed, and the focus detection accuracy is further improved.

When one of the plurality of photoelectric conversion element arrays is re-amplified in the second amplification mode, the output signal of the photoelectric conversion element array is output in the second amplification mode from the next time. The contrast calculated using the output signal of the photoelectric conversion element array amplified in the second amplification mode is compared with a third comparison value, and when the contrast is larger than the third comparison value, the photoelectric conversion element is used. By driving the array and re-amplifying the re-output signal in the first amplification mode, the gain of the output signal from the photoelectric conversion element array once set to be amplified in the second amplification mode is increased from the next amplification. It is possible to check whether or not an overflow occurs due to the lack of. If it overflows, it is considered that the target has changed or moved, so that the focus position can be detected by returning to the normal first amplification mode. Therefore, even when the target moves or the direction of the apparatus is changed, detection is performed again, so that correct focus detection can be performed.

Alternatively, when one of the plurality of photoelectric conversion element arrays is re-amplified in the second amplification mode, the output signal of the photoelectric conversion element array is output in the second amplification mode from the next time. The contrast calculated using the output signal of the photoelectric conversion element array that has been amplified and amplified in the second amplification mode is compared with a third comparison value. If the contrast is greater than the third comparison value, the second comparison value is obtained. It is determined whether the gain at the time of re-amplification in the amplification mode is the first gain or the second gain. If the gain is the second gain, the photoelectric conversion element array is driven and the re-output signal is output to the first gain. The gain is used to re-amplify in the second amplification mode, and when the gain is the first, the photoelectric conversion element array is driven, and the re-output signal is re-amplified in the first amplification mode, whereby the second amplification is performed. Amplification module Results of amplification by de, if the amplified output signal overflows, first as a first step 2
In the amplification mode, the gain can be reduced, and if the overflow still occurs, stepwise amplification can be performed so as to return to the first amplification mode as the second stage. Therefore, even when the target moves or the direction of the apparatus is changed, detection is performed again, so that correct focus detection can be performed.

Further, the plurality of photoelectric conversion element arrays are divided into a plurality of focus position detection areas, and for each of the focus position detection areas, calculation is performed using the output signal of the photoelectric conversion element array included in the focus position detection area. The contrasts are respectively compared with the first comparison value, and when all the contrasts of the same focus position detection area are smaller than the first comparison value,
By driving all the photoelectric conversion element arrays in the focus position detection area and re-amplifying the re-output signal in the second amplification mode, not for each photoelectric conversion element array, but for each focus position detection area One focus position can be detected, and the number of signal processing such as calculation of the defocus amount thereafter can be reduced. As a result, the time required for focus position detection can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration example of an autofocus camera that is an embodiment of a focus position detection device according to the present invention.

FIG. 2 is a perspective view showing an example of a configuration of an AF sensor module in an embodiment of a focus position detection device of the present invention.

FIG. 3 is a diagram illustrating a configuration example of a photoelectric conversion element array in an embodiment of a focus position detection device of the present invention.

FIG. 4 is a diagram showing a correlation calculation method in one embodiment of the focus position detection device of the present invention.

FIG. 5 is a diagram showing a correlation calculation method in one embodiment of the focus position detection device of the present invention.

FIG. 6 is a diagram illustrating a complementary calculation method in one embodiment of the focus position detection device of the present invention.

FIG. 7 is a block diagram illustrating a configuration example of a control circuit of an autofocus camera which is an embodiment of a focus position detection device of the present invention.

FIG. 8 is a diagram showing amplification in an NM mode of an output signal of a photoelectric conversion element array in one embodiment of the focus position detection device of the present invention.

FIG. 9 is a diagram illustrating amplification in an LC mode of an output signal of a photoelectric conversion element array according to an embodiment of the focus position detection apparatus of the present invention.

FIG. 10 is a diagram illustrating a configuration example of an amplifier circuit for an output signal of a photoelectric conversion element array in an embodiment of a focus position detection device of the present invention.

FIG. 11 is a diagram showing another configuration example of the amplifier circuit for the output signal of the photoelectric conversion element array in one embodiment of the focus position detection device of the present invention.

FIG. 12 is a flowchart illustrating an example of an operation in one embodiment of the focus position detection device of the present invention.

FIG. 13 is a flowchart illustrating an operation example of an embodiment of the focus position detection device of the present invention.

FIG. 14 is a flowchart illustrating an operation example of the focus position detecting apparatus according to an embodiment of the present invention.

FIG. 15 is a flowchart illustrating an operation example of an embodiment of the focus position detection device of the present invention.

FIG. 16 is a flowchart illustrating an example of an operation of the focus position detection apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 1: film surface 2: subject 41: first island 42: second island 43: third island 44: fourth island 100: camera body 140: AF sensor unit 141: sensor 200: lens body 201: optical system 301: AFCPU

Claims (5)

[Claims] A first amplification mode including a plurality of photoelectric conversion element arrays, wherein the first amplification mode amplifies an output signal of each of the photoelectric conversion element arrays based on a dark output voltage of each of the photoelectric conversion element arrays; A second amplification mode for amplifying based on a voltage according to an average value of an output signal from an effective pixel of the conversion element array, wherein each of the photoelectric conversions amplified in the first amplification mode is provided. Each of the contrasts calculated using the output signals of the element array is compared with a first comparison value. If at least one of the contrasts is smaller than the first comparison value, the contrast is smaller than the first comparison value. And a re-amplification signal for the re-output signal in the second amplification mode. 2. When at least one of the contrasts is smaller than the first comparison value, the contrast is reduced to a second comparison value.
When the contrast is larger than the second comparison value, the first gain is set. When the contrast is smaller than the second comparison value, the first gain is set. 2. The focus position detecting device according to claim 1, wherein a large second gain is set, and re-amplification is performed in the second amplification mode using the set first or second gain. 3. When any one of the plurality of photoelectric conversion element arrays is re-amplified in the second amplification mode, an output signal of the photoelectric conversion element array is output to the second amplification mode from the next time. Amplifying in the amplification mode, comparing the contrast calculated using the output signal of the photoelectric conversion element array amplified in the second amplification mode with a third comparison value, wherein the contrast is higher than the third comparison value. 3. The focus position detecting device according to claim 1, wherein, when larger, the photoelectric conversion element array is driven and the re-output signal is re-amplified in the first amplification mode. 4. When any one of the plurality of photoelectric conversion element arrays is re-amplified in the second amplification mode, an output signal of the photoelectric conversion element array is output to the second amplification mode from the next time. Amplifying in the amplification mode, comparing the contrast calculated using the output signal of the photoelectric conversion element array amplified in the second amplification mode with a third comparison value, wherein the contrast is higher than the third comparison value. If the gain is large, it is determined whether the gain when the signal is re-amplified in the second amplification mode is the first gain or the second gain. If the gain is the second gain, the photoelectric conversion element array is driven. Then, the re-output signal is re-amplified in the second amplification mode using the first gain. When the re-output signal is the first gain, the photoelectric conversion element array is driven and the re-output signal is It is reamplified focal position detecting device according to claim 2, wherein one amplification mode. 5. The method according to claim 1, wherein the plurality of photoelectric conversion element arrays are divided into a plurality of focus position detection areas, and each focus position detection area is calculated using an output signal of the photoelectric conversion element array included in the focus position detection area. Each of the contrasts obtained is compared with the first comparison value. If all the contrasts of the same focus position detection area are smaller than the first comparison value, all the photoelectric conversion element arrays of the focus position detection area are driven. The focus position detecting device according to any one of claims 1 to 4, wherein the re-output signal is re-amplified in the second amplification mode.