JP2000075201A - Focus detector, focusing device and camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect a focusing condition even when plural sensor parts do not perform focus detection with respect to the same object to be detected and when the reliability of the detection result performed by the one part of the sensor parts is low. SOLUTION: This device is provided with focusing condition detecting means (#2 to #6) independently and respectively detecting the focusing condition from the output of the plural sensor parts with respect to substantially the same part, reliability judging means (#8, #12) judging the reliability of the plural focusing conditions obtained from the respective sensor parts, a focusing condition comparing means (#9) comparing plural focusing conditions obtained from the respective plural sensor parts, and focusing condition deciding means (#10, #11, #13) deciding the focusing condition with respect to substantially the same part based on the focusing condition, the reliability, and the focusing condition compared result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus detecting device having focus state detecting means for detecting a focus state independently for substantially the same portion, a focus adjusting device provided with the focus detecting device, and The present invention relates to an improvement of a camera provided with the focus adjusting device.

[0002]

2. Description of the Related Art FIG. 15 is an expanded view showing only an objective lens and a focus detection device in order to explain the principle of focus detection.

In FIG. 1, reference numeral 108 denotes a focus detection device,
Reference numeral 09 denotes a field mask disposed near the planned focal plane of the objective lens 101, that is, a plane conjugate with the film plane. Reference numeral 110 denotes a field lens also disposed near the planned focal plane.
Numeral 11 denotes two lenses 111-1 and 111-2.
The secondary imaging system 112 is the two lenses 1 of the secondary imaging system 111
A sensor unit 113 includes two sensor arrays 112-1 and 112-2 disposed behind the corresponding lens units 11-1 and 111-2, and the sensor unit 113 includes two lenses 111- of the secondary imaging system 111.
Two openings 11 arranged corresponding to 1, 111-2
A stop 114 having 3-1 and 113-2, and 114 is an objective lens 1 including two divided regions 114-1 and 114-2.
01 exit pupil.

[0004] The field lens 110 is provided in regions 114-1 and 114-2 of the exit pupil 114 of the objective lens 101.
Corresponding to the apertures 113-1 and 113-2 of the diaphragm 113
Are the regions 114-1 of the exit pupil 114 of the objective lens 101,
It has an action of forming an image in the vicinity of 114-2, and the light beams 115-1, 115-2 transmitted through the respective regions 114-1, 114-2 of the exit pupil 114 are divided into two sensor rows 112-1,
A light quantity distribution is formed on each of 112-2.

[0005] The focus detecting device 108 is generally called a phase difference detecting method. When the image forming point of the objective lens 101 is located in front of a predetermined focal plane, that is, when the objective lens 101 is located on the objective lens 101 side. Has two sensor rows 112-1,
When the light amount distributions formed on 112-2 are close to each other, and the imaging point of the objective lens 101 is behind the expected focal plane, the two sensor arrays 112-1,
The light amount distributions formed on 112-2 are separated from each other. Moreover, the two sensor arrays 112-1 and 1
The shift amount of the light amount distribution formed on each of 12-2 is:
Since the defocus amount of the objective lens 101, that is, the defocus amount, has a certain functional relationship, if the defocus amount is calculated by an appropriate calculation means, the direction and the amount of defocus of the objective lens 101 can be detected. The position of the lens system is moved according to the direction of the defocus and the amount of defocus, the defocus amount is set to be substantially zero, and the focus detection operation ends.

In a camera incorporating such a focus detection device 108, as shown in FIG.
Is a narrow one-dimensional range with respect to the photographing screen A. This is one of the line sensor arrays 112-
1, 112-2.

In this type of focus detection device, a first sensor and a second sensor having higher detection sensitivity to the amount of light than the first sensor are juxtaposed with a light receiving element for receiving a light amount distribution guided from a focus detection optical system. However, there is a camera capable of detecting a focus even at a low luminance.

Further, during continuous shooting, a camera which enables high-speed continuous shooting by preferentially using the second sensor among these sensors (Japanese Patent Laid-Open No. 6-186473).
) Or when the moving speed of the subject is higher than a certain value, the second sensor is used (Japanese Patent Laid-Open No. 6-265774), or the focus detection result based on the signal output of the first sensor is usually used. If it is impossible or the reliability is low, focus detection is performed based on the signal output of the second sensor.
434) A camera and the like have been disclosed.

[0009] On the other hand, FIG. 17 shows an example in which the focus detection area is enlarged, and the focus detection area B is three areas with respect to the photographing screen A. This is obtained by increasing three regions in the direction orthogonal to the detection region in FIG. This FIG.
FIG. 18 shows an example in which the focus detection area shown in FIG. 18 is increased. As shown in the figure, a photoelectric conversion element having a plurality of pairs of sensor rows C to H and a focus detection optical system (not shown) corresponding thereto are provided. It is realized by using.

In a focus detection device in which a plurality of focus detection areas are set, an automatic selection mode and a manual selection mode are provided as modes for selecting the focus detection areas. Japanese Patent Application Laid-Open No. 8-262319 discloses a focus detection device that drives only a part of the sensor rows to perform focus detection, and drives a photographic lens with a focus detection result satisfying a predetermined condition.

Further, in order to quickly select a focus detection area in a focus detection device for independently detecting focus states in a plurality of areas, and to enable accurate focus detection, a plurality of focus detection results are selected. If the first obtained one satisfies a predetermined criterion, a focus detection device that sets the first obtained focus detection result as a final focus detection output irrespective of other focus detection results, JP-A-5-045
No. 576.

The above is a focus detection device using a one-dimensional sensor array, that is, a line sensor. The focus detection area is a visual field corresponding to the light receiving portion of each sensor array, and is not more than a combination of 'lines'. .

Therefore, in order to further expand the detection area, a focus detection device using a photoelectric conversion element having a two-dimensionally expanded light receiving portion, that is, an area sensor is inevitably required.

FIG. 19 shows a focus detection area B with respect to a photographing screen A in a focus detection apparatus using an area sensor. The focus detection area is greatly enlarged as compared with FIGS. 16 and 17 described above. I have.

If this area sensor adopts the phase difference detection method, it becomes an area sensor pair J in which two area areas are arranged as shown in FIG.

Conventionally, in the case of an imaging apparatus using a line sensor, there has been a problem of focus detection variation caused by the degree of application of an object image on a sensor array (so-called phase-in / phase-out). Even if an area sensor is used, this phase in / phase out (hereinafter referred to as
The problem of (phase in / out) is not improved and remains.

In the object image formed on the pair of area sensors for focus detection, the image is distorted because the image spreads two-dimensionally, and the focus detection mark on the finder deviates from the actual focus detection position. Or errors in focus detection. However, in order to improve this image distortion, a member for optically correcting is newly required,
This is an extremely difficult problem due to the technical difficulties and the complicated configuration.

[0018]

SUMMARY OF THE INVENTION In a focus detecting device capable of detecting a focus two-dimensionally and continuously over a wide range on a photographing screen or an observation screen, a continuous light receiving unit is used.
A plurality of dimensionally spread photoelectric conversion elements are arranged in such a manner that adjacent sensor rows are out of phase with respect to the object image, and are generated by the degree of application of the object image on the sensor rows (so-called phase in / out). Japanese Patent Application Laid-Open No. H10-104503 has proposed a method of improving the variation in detection of focus detection values.

However, when the same subject is detected by two pairs of sensor units having different phases, the focus detection error caused by the influence of the so-called phase in / out can be improved. However, since the position of the subject for which focus detection is performed is slightly different, the focus detection error cannot always be improved.

For example, there are cases where two sensor units detect the focus of different subjects. In this case, if the focus detection results obtained by the two sensor units are combined, a correct focus detection result cannot be obtained. Further, when the reliability of the focus detection result of one of the sensor units is low, the synthesized focus detection result becomes worse than the focus detection result of the highly reliable sensor.

(Object of the Invention) An object of the present invention is to provide a method for detecting a focus even when a plurality of sensor units do not perform focus detection for the same detection target or when the reliability of detection results of some sensor units is low. An object of the present invention is to provide a focus detection device, a focus adjustment device, and a camera capable of detecting a focus state well.

[0022]

In order to achieve the above object, the present invention according to the first to eighth aspects of the present invention focuses on a substantially identical portion independently of the output of each of a plurality of sensor units. Focus state detecting means for detecting, reliability determining means for determining reliability of a plurality of focus states obtained by each of the sensor units, and focus state comparing a plurality of focus states obtained by each of the plurality of sensor units The present invention is a focus detection device including a comparison unit, and a focus state determination unit that determines a focus state for the substantially same portion based on the focus state, the reliability, and the focus state comparison result.

According to a ninth aspect of the present invention, there is provided a focus detection device comprising: a focus detection device; and a driving unit for driving an optical system based on a focus state from the focus detection device. Focus adjusting device.

According to another aspect of the present invention, there is provided a camera having a focusing device according to the ninth aspect.

In the above configuration, when the focus state is detected by a plurality of sensor units for substantially the same portion, if the focus detection can be performed on the exactly same detection target with high reliability, the detection results of the plurality of sensor units can be obtained. (For example, by averaging), the accuracy of detection of the focus state is improved. However, the focus state of the same detection target is not detected by a plurality of sensor units, In the case where the reliability of focus detection by the sensor units is low, using the detection results of the plurality of sensor units may deteriorate the detection accuracy.
For this reason, the final focus state is determined by using the reliability of each focus state obtained by a plurality of sensor units and comparing the respective focus state detection results.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on illustrated embodiments.

FIG. 1 is an optical layout diagram of components for performing focus detection in a plurality of focus detection areas of a single-lens reflex camera according to an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an optical axis of an objective lens (not shown) disposed on the left side of the figure, 2 denotes a silver halide film disposed at a focal position of the objective lens, and 3 denotes an optical axis of the objective lens. The semi-transmissive main mirror 4 arranged above is a first reflecting mirror similarly arranged obliquely on the optical axis 1 of the objective lens,
Is a paraxial image plane conjugate to the film 2 by the first reflecting mirror 4, 6 is a second reflecting mirror for focus detection, 7 is an infrared cut filter for blocking infrared rays, and 8 is two apertures 8 -1,
A stop having an aperture 8-2, 9 is provided with two apertures 8-
Two lenses 9-1 arranged corresponding to 1, 8-2,
Secondary imaging system having 9-2, 10 is a third reflecting mirror for focus detection, 11 is two area sensors 11-1, 11-2.
Is a photoelectric conversion element having:

Here, the first reflecting mirror 4 has a curvature, and has a convergent power for projecting the two apertures 8-1 and 8-2 of the stop 8 near the exit pupil of an objective lens (not shown). have. In addition, the first reflecting mirror 4 has a metal film such as aluminum or silver deposited so that only a necessary area reflects light, and also functions as a field mask that limits a range in which focus detection is performed. I have. In the other reflecting mirrors 6 and 10 as well, only a necessary minimum area is vapor-deposited in order to reduce stray light incident on the photoelectric conversion element 11. Each mirror 4,
It is also effective to apply a light-absorbing paint or the like to the areas that do not function as the reflection surfaces of the light-emitting elements 6 and 10, or to provide light-shielding members in close proximity.

FIG. 2 is a plan view of the stop 8, in which two horizontally long openings 8-1 and 8-2 are arranged in a direction in which the opening width is narrow. The dotted lines in the figure indicate the lenses 9-1 and 9-2 of the secondary imaging system 9 disposed behind the apertures 8-1 and 8-2 of the diaphragm 8 in correspondence with the apertures 8-1 and 8-2. It is.

FIG. 3 is a schematic plan view of the photoelectric conversion element 11, and the two area sensors 11-1 and 11 shown in FIG.
-2 is a two-dimensional pixel (sensor part) as shown in this figure
Are arranged, and two area sensors are arranged at positions corresponding to an object image formed on the photoelectric conversion element.

FIG. 4 shows the phase in on a conventional sensor array.
20-1 is a diagram showing / out, where 20-1 is one sensor row,
One is shown, and 20-2 shows an object image on the sensor array.

FIG. 5 is a diagram showing the focus detection variation caused by the phase in / out of the object image on the sensor array in FIG. 4, and the object image indicated by 20-2 in FIG. 4 has moved in the direction of the arrow. FIG. 6 is a diagram showing the position of the subject image of each photoelectric conversion element d, e, and f on the horizontal axis and the output level of the element array on the vertical axis, showing the change of the focus detection value according to the position of each photoelectric conversion element. ing.

As can be seen from FIG. 5, the variation in the focus detection value caused by the phase in / out of the object image on the sensor array indicates a change in which the width of the photoelectric conversion element is one cycle.

As a method of improving the focus detection variation caused by the phase in / out and always enabling stable detection of the defocus amount, it is known to arrange as shown in FIG. In FIG. 6, pixels a to g (sensor unit) on one line and pixels h to n on the other line are 1
/ 2 elements. FIG. 7 shows focus detection values obtained by the sensor array.

In FIG. 7, the change in the focus detection value 26-1 indicated by the solid line by the pixels a to g in the case of FIG.
The change 26-2 in the focus detection value indicated by the dotted line due to .about.n is detected, and simply adding them together results in zero indicated as 26-3. There is a method of arranging the sensor rows in a phase shifted relationship with each other and obtaining one focus detection value based on the outputs of a plurality of adjacent sensor rows. The phase difference between the adjacent sensor rows is two times the width of the photoelectric conversion element. It is clear from the results of theoretical experiments that the relationship shifted by one-half pitch has the greatest improvement effect.

However, there have been many patent applications in which adjacent sensor rows are displaced from each other by a predetermined amount (for example, Japanese Patent Application Laid-Open No. 59-105606). However, simply shifting the adjacent sensor rows by a predetermined amount will cause the object image to be distorted, causing the phase difference between the adjacent sensor rows and the object image to differ from the predetermined amount, and a sufficient improvement effect will be obtained. I will not be able to.

FIG. 8 shows a photoelectric conversion element according to an embodiment in which this problem is solved, and FIG. 9 is a partially enlarged view of FIG. In FIG. 9, 24-1 indicates a pixel (photoelectric conversion element), and 24-2 indicates distortion of an object image on each pixel.

FIG. 10 is an enlarged view of a part of the sensor array of FIG. 9, and shows the sensor array 27-1 adjacent to the sensor array 27-1.
-2 is arranged at a position out of phase with respect to the object image 27-3 indicated by oblique lines. The phase of the object image 27-3 on the sensor array is shifted by a half pitch between adjacent lines of the sensor arrays 27-1 and 27-2. The difference from FIG. 6 is that the photoelectric conversion element has a configuration in which a plurality of adjacent lines are arranged corresponding to the distortion of the object image, and the positions of the light flux from the subject are shifted between the adjacent lines. It is characterized by.

Therefore, in the present embodiment, adjacent sensor rows are arranged in such a manner that they are displaced from each other by a predetermined pitch of pixels (a half pitch in the present embodiment) with respect to the position of a light beam from a subject. Since the final focus detection output is obtained by comparing the defocus amount and the reliability detected from the outputs of the sensor rows and the respective defocus amounts, the influence of the focus detection variation caused by the phase in / out is prevented. Furthermore, even when the same subject is not focus-detected, or when the detection results of some sensors are poor, focus detection can be performed with high accuracy.

In the above configuration, the light beams 12-1 and 12-2 from the objective lens (not shown) in FIG. 1 pass through the main mirror 3, and then follow the inclination of the main mirror 3 by the first reflecting mirror 4. After being changed in direction again by the second reflecting mirror 6, the light passes through the infrared cut filter 7 and the two apertures 8-1 and 8-2 of the stop 8, and each of the secondary imaging systems 9 Lens 9-
The light is condensed by 1 and 9-2 and reaches the area sensors 11-1 and 11-2 of the photoelectric conversion element 11 via the third reflecting mirror 10, respectively.

Although the light beams 12-1 and 12-2 in FIG. 1 indicate the light beams that form an image at the center of the film 2, the light beams that form an image at other positions also travel through the same path. After reaching the conversion element 11, two light quantity distributions corresponding to a predetermined two-dimensional area on the film 2 as a whole are formed on each of the area sensors 11-1 and 11-2 of the photoelectric conversion element 11.

In this embodiment, the first reflecting mirror 4 is composed of a part of a curved surface formed by rotating a quadratic curve around an axis, and a spheroid is particularly preferably used. In FIG. 1, the surface shape of the first reflecting mirror 4 consists of a part of a spheroid formed by rotating an ellipse 21 having a vertex at a point 20 around an axis 22, and its focal point is the second reflection. The vicinity of the image position 23 at the center of the stop 8 by the mirror 6 and the translucent main mirror 3
Is set in the vicinity of a point (not shown) on the extension of the optical axis 24 after transmission. If the point on the extension of the optical axis 24 is focused near the exit pupil position of the objective lens (or the average exit pupil position when various objective lenses are used interchangeably), the objective lens The exit position and the incident position of the secondary imaging system are substantially imaged, and the first reflecting mirror 4 functions as an ideal field lens. As is clear from FIG. 1, what is optically used as the first reflecting mirror 4 is a region not including the rotation axis and the vertex of the spheroid.

In the present embodiment, the light incident on the secondary imaging system 9 is forcibly refracted by making the first surface on the incident side of the secondary imaging system 9 concave. And a good and uniform imaging performance is secured over a wide range of the two-dimensional area of the photoelectric conversion element 11.

The two light quantity distributions obtained in this manner are separated based on the same principle as that described with reference to FIG. 15, ie, the two area sensors 11 shown in FIG.
By calculating the relative positional relationship between −1 and 11-2 in the vertical direction at each position of the area sensors 11-1 and 11-2,
The focus state of the objective lens can be detected two-dimensionally.

The first reflecting mirror 4 is retracted out of the photographing optical path when photographing on the silver halide film 2, similarly to the main mirror 3.

Next, the photoelectric conversion element 11 will be described in detail.

FIG. 11 shows the distribution of the focus detection area in the present embodiment as viewed from the finder of the camera.

In this embodiment, as shown in FIG.
Focus detection can be performed in a total of 55 areas (square in the figure indicates one area) of 11 right and left and 5 upper and lower divisions at the center of 1. The two area sensors 11-1 and 11-2 of the photoelectric conversion element 11 are divided into 55 so as to correspond to each of the 55 divided regions. The 55 divided area viewed from the finder is divided into 55 divided areas on both sensor rows 11-1 and 11-2 in FIG. 8, and one sensor row 11-1 shown in FIG. The sensor array 11-1 is divided into regions, and the sensor arrays 11-1 are arranged along the distortion of the lens system, and adjacent sensor arrays are shifted from each other by 画素 pixel. As a result, it is possible to greatly reduce and improve the focus detection variation due to the phase in / out that occurs at the time of focus detection by the area sensor.

The correspondence between the focus detection area and the photoelectric conversion element in FIG. 11 will be described in detail with reference to FIG. FIG.
It is the figure which expanded the upper right part of FIG.

As shown in FIG. 8, this photoelectric conversion element has another pair, but only one of them is shown here. In FIG. 11, the sensor units (pixels) corresponding to the focus detection area a11 at the upper right are A21-1 and A2-1 in FIG.
22-1 (on the area sensor 11-1) and A21-2 and A22-2 (not shown) on the other sensor section 11-2.
It is. In FIG. 11, a focus detection area b below a11
The sensor units for performing the focus detection of the 11 parts include the sensor units B21-1 and B22-1 of FIG.
22-2. Similarly, the sensors B17-1 and B18-1 and the B (not shown) correspond to the focus detection area b09.
17-2 and B18-2.

FIG. 13 is a block diagram showing an example of the electrical configuration of a camera provided with each of the focus detection devices described above. First, the configuration of each unit will be described.

In FIG. 13, PRS is a camera control device, for example, a CPU (central processing unit), RO
It is a one-chip microcomputer (hereinafter, referred to as a microcomputer) having M, RAM, A / D, and D / A conversion functions. The microcomputer PRS performs a series of camera operations such as an automatic exposure control function, an automatic focus adjustment function, and film winding / rewinding according to a camera sequence program stored in the ROM. For this purpose, the microcomputer PRS communicates with the peripheral circuits in the camera body and the in-lens control device by using the communication signals SO, SI, SCLK and the communication selection signals CLCM, CDDR, CICC, and controls each circuit and lens. Control behavior.

SO is a data signal output from the microcomputer PRS, SI is a data signal input to the microcomputer PRS, and SCLK is a synchronous clock of the signals SO and SI.

LCM is a lens communication buffer circuit,
When the camera is in operation, power is supplied to the lens power supply terminal VL and a selection signal C from the microcomputer PRS is supplied.
When the LCM is at a high potential level (hereinafter, described as “H” and a low potential level is described as “L”), it serves as a communication buffer between the camera and the lens.

When the microcomputer PRS sets the selection signal CLCM to "H" and sends out predetermined data from the data signal SO in synchronization with the synchronization clock SCLK, the lens communication buffer circuit LCM is connected via the camera-lens communication contact. The synchronous clock SCLK and the buffer signals LCK and DCL of the data signal SO are output to the lens. At the same time, a buffer signal of the signal DLC from the lens LNS is output to the data signal SI, and the microcomputer PRS inputs lens data from the data signal SI in synchronization with the synchronous clock SCLK.

DDR is a circuit for detecting and displaying various switches SWS, is selected when the signal CDDR is "H", and is controlled by the microcomputer PRS using the data signals SO and SI and the synchronous clock SCLK. That is, based on data sent from the microcomputer PRS, the display of the display member DSP of the camera is switched, and the on / off state of various operation members of the camera is notified to the microcomputer PRS by communication. OLC is an external liquid crystal display device located above the camera, and ILC is a viewfinder internal liquid crystal display device. In the present embodiment, the setting of the focus detection operation area, etc.
The switch SW belonging to the detection and display circuit DDR
Going in S.

SW1 and SW2 are switches linked to a release button (not shown). The switch SW1 is turned on when the release button is pressed in the first stage, and subsequently the second switch is pressed.
The switch SW2 is turned on by pressing down in stages. Microcomputer PR
In step S, photometry and automatic focus adjustment are performed when the switch SW1 is turned on, and exposure control and subsequent film winding are performed with the switch SW2 turned on as a trigger.

The switch SW2 is connected to the "interrupt input terminal" of the microcomputer PRS. Even when the program is executed when the switch SW1 is turned on, an interrupt is generated by turning on the switch SW2, and the control is immediately transferred to a predetermined interrupt program. it can.

MTR1 is a motor for feeding the film, and MTR2 is a motor for mirror up / down and charging of the shutter spring. The normal rotation and the reverse rotation are controlled by respective drive circuits MDR1 and MDR2. The signals M1F, which are input from the microcomputer PRS to the drive circuits MDR1 and MDR2,
M1R, M2F and M2R are forward and reverse control signals for motor control.

MG1 and MG2 are magnets for starting the shutter front curtain and rear curtain, respectively, and control signals SMG1 and SM2.
G2, electricity is supplied by the amplification transistors TR1 and TR2, and the microcomputer PRS controls the shutter. Since the motor drive circuits MDR1 and MDR2 and the shutter control do not directly relate to the present invention, a detailed description is omitted.

The buffer signal DCL input to the control circuit LPRS in the lens LNS in synchronization with the buffer signal LCK
Is data of an instruction from the camera to the lens LNS, and the operation of the lens LNS for the instruction is predetermined. The control circuit LPRS in the lens LNS analyzes the command in accordance with a predetermined procedure, and performs the operation of focus adjustment and aperture control, the operation status of each part of the lens LNS from the output DLC (the drive status of the focus adjustment optical system, the drive status of the aperture, etc.). Etc.) and various parameters (open F number, focal length, coefficient of defocus amount vs. movement amount of focus adjustment optical system, various focus correction amounts, etc.) are output. ZMTR is a zoom motor driven by signals ZMR and ZMF.

This embodiment shows an example of a zoom lens. When a focus adjustment command is sent from a camera, a focus adjustment motor LMTR is sent to a signal LMF in accordance with the drive amount and direction sent at the same time. , LMR to move the optical system forward and backward in the optical axis direction to perform focus adjustment. The amount of movement of the optical system is monitored by a pulse signal SENCF of an encoder circuit ENCF that detects a pattern of a pulse plate that rotates in conjunction with the optical system with a photocoupler and outputs a number of pulses corresponding to the amount of movement. It is counted by a counter in the control circuit LPRS in the LNS, and when the predetermined movement of the front lens of the lens is completed, the control circuit L in the lens LNS
The PRS itself sets the signals LMF and LMR to 'L' to brake the motor LMTR.

For this reason, once the focus adjustment command is sent from the camera, the microcomputer PR, which is a control device of the camera,
S does not need to be involved in driving the lens at all until the driving of the lens is completed. Further, when a request is received from the camera, the contents of the counter can be transmitted to the camera.

When an aperture control command is sent from the camera, a well-known stepping motor DMTR for driving an aperture is driven in accordance with the number of aperture stages sent at the same time. Since the stepping motor DMTR can perform open control, it does not require an encoder for monitoring the operation.

ENCZ is an encoder circuit attached to the zoom optical system, and the control circuit LPRS in the lens LNS receives the signal SENCZ from the encoder circuit ENCZ to detect the zoom position. Control circuit LPR in lens LNS
In S, lens parameters at each zoom position are stored, and when requested by the microcomputer PRS on the camera side, parameters corresponding to the current zoom position are sent to the camera side.

The ICC is a focus detection area sensor composed of a CCD or the like which is a photoelectric conversion element and a focus detection circuit which is a drive control circuit thereof. The ICC is selected when the selection signal CICC is "H" and the data signal is outputted. It is controlled by the microcomputer PRS using SO, SI and the synchronization signal SCLK.

ΦV, φH, and φR are read signals of the area sensor output and reset signals. A sensor control signal is generated by a drive circuit in the focus detection circuit ICC based on the signal from the microcomputer PRS. The sensor output is amplified after reading from the photoelectric conversion element, and is input to the analog input terminal of the microcomputer PRS as an output signal IMAGE. The microcomputer PRS converts the output signal IMAGE from analog to digital and converts the digital value to a predetermined address on the RAM. Stored sequentially. Focus detection is performed using these digitally converted signals.

VR is an accumulation termination determination level common to the above-described differential amplifiers, INT is an accumulation termination output signal,
ICLK is a reference clock signal of a control circuit section in the focus detection circuit ICC.

In the entire camera system described above, especially the operation of the focus detection circuit ICC performs the operation of focus detection by each area sensor, and the result is set to an appropriate focus point by the control circuit LPRS in the lens LNS via the microcomputer PRS. By moving and holding the lens system and then operating the shutter, a focused image can be obtained.

In FIG. 13, the camera and the lens LNS are used.
Are represented as separate bodies (lenses can be exchanged), but the present invention is not limited to these without any problem even if the camera and lens are integrated.

Here, the focus detection function will be described in detail with reference to the flowchart of FIG.

The purpose of this subroutine "focus detection" is to detect the focus state (defocus amount) of a plurality of sensors in a specific focus detection area and ultimately detect the focus of the focus detection area. Then, the defocus amount obtained in this subroutine "focus detection" is converted into a lens drive amount according to a predetermined algorithm, and is used for lens drive.

First, when a predetermined operation is performed on the camera, the microcomputer PRS calls a subroutine "focus detection" (step # 1).

After calling this subroutine, in step # 2, the microcomputer PRS causes the focus detection circuit ICC
And starts accumulation of the focus detection area sensor.
In this embodiment, a case will be described in which the focus detection is not performed by all the area sensors, but the accumulation of a plurality of sensor units in a predetermined focus detection area is to be controlled. In the case of a plurality of focus detection areas, the following calculation may be performed for each focus detection area.

In the next step # 3, the process waits for the completion of the accumulation in the sensor section. In this embodiment, the accumulation start of the sensor unit is all started at the same time, but the accumulation end is partially and independently performed by the light amount distribution on the sensor unit. In other words, the accumulation time is short in a portion with a large amount of light and is long in a portion with a small amount of light.

In step # 4, the sensor section is read from the portion where the accumulation has been completed as described above, and the sensor signal is stored in the RAM in the microcomputer PRS. In the next step # 5, the defocus amount is calculated by calculating the sensor signal read into the RAM according to a predetermined algorithm, and in the following step # 6, the reliability of the calculated defocus amount is calculated. This reliability is calculated based on the contrast of the sensor image, the degree of coincidence between the two images, and the like. Here, the case where the reliability is calculated after calculating the defocus amount is described as an example.However, the calculation is not necessarily limited to the calculation at the time of defocus calculation. It may be performed prior to the defocus calculation.

After the calculation of the focus state of the pair of sensor units is completed, it is next determined in step # 7 whether the defocus calculation of all the sensor units has been completed. In this example,
If the defocus calculation of a plurality of sensor units for a predetermined focus detection area is completed instead of the defocus calculation of all the sensor units in the area sensor, the process proceeds to step # 8. If the defocus calculation has not been completed, the process returns to step # 3, and waits for the end of accumulation again.

When the defocus calculation of the plurality of sensor units with respect to the predetermined focus detection area is completed as described above, the process proceeds to step # 8, where the reliability of the defocus amount obtained from the target sensor unit is determined by the predetermined value. It is determined whether the criteria are satisfied. As a result, if the reliability of the plurality of sensors in the predetermined focus detection area is good, the process proceeds to step # 9, and if not, the process proceeds to step # 12. That is, if there are two pairs of sensor units in the predetermined focus detection area, the defocus amount and the reliability of each of the two are detected, and if both are good, the process proceeds to step # 9.

In step # 9, the difference between the two defocus amounts is calculated, and it is compared whether the difference is larger than a predetermined value. The difference between the defocus values of the two sensor units should be smaller than the defocus difference that can originally occur in phase in / out. However, the difference between the two defocus amounts increases when the two sensors detect the focus of different objects, or when one of the sensor units performs erroneous focus detection.

If the difference between the defocus amounts is small, the process proceeds to step # 10, where the two defocus amounts are combined.
A final defocus amount of the focus detection area is obtained.
An average value or the like is usually used for combining the two defocus amounts. If the difference between the defocus amounts is large, the process proceeds to step # 11, and one of the defocus amounts is set as the final defocus amount. Many methods for selecting one from a plurality of focus detection results have already been proposed.
Generally, a defocus amount closer to the camera is employed.

If the reliability is all good in step # 8, the final defocus amount is calculated in this way, and in step # 15, this subroutine "focus detection" is performed.
If the reliability of the defocus amounts calculated by all the sensor units is good in step # 8, the process proceeds to step # 12, where the defocus reliability obtained by at least one of the sensor units is It is determined whether or not it is good, and if it is good, the process proceeds to step # 13, and the defocus amount obtained by the sensor unit having good reliability is set as the final focus detection result. If the defocus reliability obtained by at least one of the sensor units is not good, the process proceeds to step # 14, where an NG flag indicating that focus detection has not been performed is set. After the execution of step # 13 or step # 14, the process proceeds to step # 15, and the subroutine "focus detection" is returned.

(Correspondence between the Invention and the Embodiment) In the above embodiment, the part for performing the operations of steps # 2 to # 6 in FIG. 14 in the focus detection circuit ICC and the microcomputer PRS corresponds to the focus state detection means of the present invention. The operation of steps # 8 and # 12 in FIG. 14 in the microcomputer PRS is performed by the reliability determining means of the present invention.
The portion performing the operation of No. 9 corresponds to the focus state comparing means of the present invention, and the portion performing the operations of steps # 10, # 11 or # 13 in FIG. 14 in the microcomputer PRS corresponds to the focus state determining means of the present invention. .

The focus detection area a1 in FIG.
1, b11, b09, etc. are substantially the same in the present invention or the focus detection area, and the sensor units A21-1 and A21 in FIG.
-2 and the like correspond to the sensor unit of the present invention, respectively.

(Modification) In this embodiment, two sensor sections are arranged corresponding to a predetermined focus detection area, and the final focus detection result is determined from the two focus detection results obtained therefrom. However, the number of sensor units in one focus detection area is not limited to two, and the case where more than two focus detection results are obtained in one focus detection area is considered in the same manner as in the present embodiment. Then, the difference between the defocus amounts is obtained from the focus detection results having high reliability, those having a large difference are excluded, and only the focus detection results having a small difference may be synthesized.

Further, although the incident light from the objective lens is separated into two images having two parallaxes and then formed into an image with respect to the area sensor, they are formed through two lenses separated by a predetermined base line length. The two incident images may be incident on each area sensor.

Further, the incident light from the photographing lens is separated into two images having two parallaxes, and the focus is detected by a plurality of pairs of sensors whose phases are shifted. If so, the separation directions of the two images may be orthogonal to each other.

In the above embodiment, an example in which the present invention is applied to a single-lens reflex camera is described. However, the present invention is not limited to this, and can be applied to a camera such as a video camera. Further, the present invention can be applied to a single focus detection device that requires focus detection, a focus adjustment device that requires focus adjustment based on the focus detection result, and further to an optical device such as an observation device equipped with these devices. is there.

[0089]

As described above, according to the present invention,
A focus detection device that can accurately detect a focus state even when a plurality of sensor units do not perform focus detection on the same detection target or when the reliability of detection results of some sensor units is low. It is possible to provide a focusing device and a camera.

[Brief description of the drawings]

FIG. 1 is a configuration diagram schematically showing an arrangement of an optical system of a focus detection device provided in a camera according to an embodiment of the present invention.

FIG. 2 shows a diaphragm and 2 provided in the focus detection device of FIG.
It is a figure showing a next imaging system.

FIG. 3 is a diagram showing a photoelectric conversion element provided in the focus detection device of FIG. 1;

FIG. 4 is a diagram showing an object image on a conventional photoelectric conversion element array.

FIG. 5 is a diagram illustrating a change in a focus detection value due to a general phase in / out.

FIG. 6 is a view showing an object image on a photoelectric conversion element array provided in the focus detection device of FIG. 1;

FIG. 7 shows a phase in / in one embodiment of the present invention.
FIG. 7 is a diagram illustrating a change in a focus detection value due to out.

FIG. 8 is a diagram illustrating distortion of an object image and element arrangement of the entire area sensor according to the embodiment of the present invention.

FIG. 9 is a diagram illustrating distortion of an object image and element arrangement of an area sensor according to the embodiment of the present invention.

FIG. 10 is a diagram illustrating a part of an enlarged image of the area sensor according to the embodiment of the present invention, showing distortion of a subject image;

FIG. 11 is a diagram showing a distribution of focus detection areas according to an embodiment of the present invention.

FIG. 12 is a diagram illustrating a correspondence relationship between a focus detection area and a photoelectric conversion element in FIG. 11;

FIG. 13 is a block diagram illustrating a circuit configuration of a camera and a lens according to an embodiment of the present invention.

FIG. 14 is a flowchart illustrating a focus detection operation of the camera according to the embodiment of the present invention.

FIG. 15 is an optical arrangement diagram for explaining a conventional focus detection device.

FIG. 16 is a diagram showing a distribution of a conventional focus detection area.

FIG. 17 is a diagram showing a distribution of a conventional focus detection area.

FIG. 18 is a diagram illustrating a conventional photoelectric conversion element and its accumulation control.

FIG. 19 is an explanatory diagram of a case where a focus detection area is two-dimensionally enlarged by a conventional method.

FIG. 20 is an explanatory diagram in a case where a focus detection area is two-dimensionally enlarged by a conventional method.

[Explanation of symbols]

 111 Secondary imaging system 112 Photoelectric conversion element 113 Aperture 114 Exit pupil of objective lens A Imaging screen area B Focus detection area PRS microcomputer SDR sensor drive circuit LNS lens ICC focus detection device a11, b11, b09 Focus detection area A21-1, A22-1 Sensor section B21-1 and B22-1 Sensor section B18-1 and B17-1 Sensor section

Claims (10)

[Claims] 1. A focus state detecting means for detecting a focus state independently from an output of each of a plurality of sensor units for substantially the same portion, and a reliability of a plurality of focus states obtained by each of the sensor units. A reliability determination unit that determines the focus state, a focus state comparison unit that compares a plurality of focus states obtained by each of the plurality of sensor units, and the substantial state based on the focus state, the reliability, and the focus state comparison result. A focus state determining means for determining a focus state for the same part. 2. The substantially same portion is a predetermined focus detection area, the focus state is a defocus amount, and the focus state detection means corresponds to the predetermined focus detection area. The focus detection device according to claim 1, wherein a defocus amount obtained independently from outputs of the plurality of sensor units arranged in a vertical direction is detected. 3. The focus state comparison means compares a difference between a plurality of defocus amounts obtained by the plurality of sensor units, and the focus state determination means determines whether the difference between the plurality of defocus amounts is a predetermined value. If the value is smaller than the value, the defocus amount for the substantially same portion is determined using each of the plurality of defocus amounts obtained by the plurality of sensor units, and the defocus amount of the plurality of defocus amounts is determined. When the difference is larger than a predetermined value, one of the plurality of defocus amounts obtained by the plurality of sensor units is determined as a defocus amount for the substantially same portion based on a predetermined algorithm. 3. The focus detection device according to claim 2, wherein: 4. The method according to claim 1, wherein the focus state determining unit determines that the reliability of each of the plurality of defocus amounts detected by the plurality of sensor units is good. If the difference between the defocus amounts is smaller than a predetermined value, a defocus amount for the substantially same portion is determined using each of the plurality of defocus amounts, and the difference between the defocus amounts is smaller than a predetermined value. 4. The focus detection device according to claim 3, wherein if the difference is larger, one of the plurality of defocus amounts is determined as a defocus amount for the substantially same portion based on a predetermined algorithm. 5. The method according to claim 1, wherein when the difference between the plurality of defocus amounts is smaller than a predetermined value, the focus state determination unit calculates the average value of the plurality of defocus amounts with respect to the substantially same portion. The focus detection device according to claim 3, wherein the focus detection device determines the value. 6. The focus state determination means, when the reliability determination means determines that one of the focus states detected by the plurality of sensor units has good reliability, the reliability is determined. 5. The focus detection device according to claim 3, wherein the defocus amount determined to be good is determined as the defocus amount for the substantially same portion. 7. The reliability determination means determines the reliability of a plurality of defocus amounts based on the contrast of images formed on the plurality of sensor units or the degree of coincidence of two images forming a pair. The focus detection device according to claim 4 or 6, wherein 8. The focus state detecting means includes: a pair of optical systems; and a pair of photoelectric conversion elements having a plurality of sensor units on each of which an object image formed by the pair of optical systems is formed. And a means for detecting a focus state from a relative positional relationship between the respective object images on the pair of photoelectric conversion elements, and each of the pair of photoelectric conversion elements causes a displacement of the object image. A plurality of sensor rows formed by connecting a plurality of sensor units arranged one-dimensionally in the same direction as the direction are configured to be adjacent to each other, and the adjacent sensor rows are located at positions different in phase with respect to the object image. The focus detection device according to claim 1, wherein the focus detection device is disposed. 9. A focus adjustment device, comprising: the focus detection device according to claim 1; and driving means for driving an optical system based on a focus state from the focus detection device. 10. A camera comprising the focus adjusting device according to claim 9.