JPH0915486A - Interchangeable lens type camera system - Google Patents

Abstract

PURPOSE: To provide an interchangeable type camera system capable of being stably in focus on an aimed main subject on every photographing condition for every subject whatever lens is attached. CONSTITUTION: A lens unit which can be attached to/detached from a camera body is the lens unit provided with a focusing lens 105 for performing focusing, a focusing means for driving the focusing lens based on a focus evaluated value transmitted from a camera body, a range-finding frame size control part 120 deciding the size of a focus detection region in the screen, and a communication means transferring information on the size of the focus detection region decided by the control part 120 to the camera body.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an interchangeable lens type camera system suitable for use in video cameras and the like.

[0002]

2. Description of the Related Art Conventionally, as an automatic focusing device used in a video device such as a video camera, a high frequency component is extracted from a video signal obtained from an image pickup device such as a CCD so that the high frequency component is maximized. A so-called hill-climbing method is known in which the photographing lens is driven to adjust the focus.

Such an automatic focus adjustment method has an advantage that a special optical member for focus adjustment is not required, and the focus can be accurately adjusted regardless of the distance even at a long distance.

An example in which this type of automatic focus adjustment system is used in an interchangeable lens type video camera in which the lens can be exchanged will be described with reference to FIG.

In a conventional variable-magnification lens unit, a variable-magnification lens 602 and a correction lens 603 are mechanically connected by a cam. When the variable-magnification operation is performed manually or electrically, the variable-magnification lens 6 is used.
02 and the correction lens 603 move integrally. The zoom lens 602 and the correction lens 603 are collectively referred to as a zoom lens.

In such a lens system, the front lens 601 serves as a focus lens, and the focus is adjusted by moving in the optical axis direction. The light passing through these lens groups is imaged on the image pickup surface of the image pickup device 604, photoelectrically converted into an electric signal, and output as a video signal.

This video signal is sent to the CDS / AGC circuit 60.
Sampled and held at 5 and amplified to a predetermined level,
It is converted to digital video data by the A / D converter 606, input to the process circuit of the camera, converted to a standardized standard television signal, and input to a bandpass filter (hereinafter BPF) 607. It

The BPF 607 extracts a high-frequency component that changes according to the focus state in the video signal, and the gate circuit 60
At 8, the signal corresponding to the portion set in the focus detection area in the screen is extracted, and the peak hold circuit 608 performs peak hold at intervals synchronized with an integral multiple of the vertical sync signal to generate an AF evaluation value.

The AF evaluation value is taken into the AF microcomputer 610 on the camera body side, and the drive speed of the focus lens (focus motor) according to the degree of focus in the AF microcomputer 610 and the motor for increasing the AF evaluation value. The drive direction is determined, and the speed and direction of the focus motor are sent to the lens microcomputer 611 in the lens unit 616.

The lens microcomputer 611 drives the focus motor 613 via the motor driver 612 as instructed by the AF microcomputer 610 on the camera body side, and moves the focus lens 601 in the optical axis direction to perform focus adjustment.

Further, according to the operation state of the zoom switch 618, the AF microcomputer 610 causes the zoom lenses 602 and 6 to operate.
03 drive direction and drive speed are determined, and the lens unit 6
The zoom motor driver 614 in 16 drives the zoom motor 615 to drive the zoom lenses 602 and 603.

Further, the camera body 617 can be separated from the lens unit 616, and by connecting another lens unit, the photographing range is expanded.

[0013]

However, in the above-described conventional example, since the lenses can be exchanged, the AF control and the setting of the focus detection area to be extracted from the screen are provided in the main body, which is optimal for a specific lens. When the focus detection area is determined as described above, it may not be optimal for other lenses, and it is difficult to obtain optimal performance for all mountable lenses. For example, if the focus detection area is set to the wide-angle priority lens and the telephoto priority lens is attached, the subject is greatly changed in the focus detection area as the screen is enlarged, so that the AF evaluation value also changes drastically. However, the AF performance may deteriorate.

Further, the enlargement of the screen causes a decrease in the contrast of the subject, which causes a blur stop. Even if the same lens is used, if the focal length changes due to zooming or electronic zooming, the above-mentioned problems occur.

An object of the present invention is to solve the above-mentioned problems, and no matter what kind of lens is attached, it is possible to stably focus on a main subject of interest under all subjects and shooting conditions, and an interchangeable lens type camera system. Is to provide.

[0016]

In order to solve the above-mentioned problems, according to the invention described in claim 1 of the present application, a lens unit detachable from the camera body is provided.
Focus lens group for performing focus adjustment, focus adjusting means for driving the focus lens group based on the focus evaluation value transmitted from the camera body, and area control for determining the size of the focus detection area in the screen And a communication unit that delivers the size information of the focus detection area determined by the area control unit to the camera body.

According to a second aspect of the present invention, in the first aspect, the area control means changes the size of the focus detection area according to the focal length of the lens unit. Configure.

According to a third aspect of the present invention, there is provided a camera in which the lens unit can be exchanged, and image pickup means for converting an image formed through the lens unit into an electric signal. Extraction means for extracting a focus signal in a focus detection area in the screen from the image pickup signal output from the image pickup means, and predetermined focus information indicating the size of the focus detection area from the lens unit to detect the focus. An interchangeable lens camera including area control means for controlling the size of the area, and transmission means for transmitting the output of the extraction means corresponding to the focus detection area determined by the area control means to the lens unit. Features a system.

According to a fourth aspect of the present invention, in the third aspect, a region position control means for changing the set position of the focus detection region in the screen is further provided.

According to the invention of claim 5 in the present application, in the interchangeable lens type camera system in which the lens unit can be exchanged with respect to the camera body, the first lens for performing the zooming operation on the lens unit side. Group, a second lens group for focus adjustment, detection means for detecting the positions of the first and second lens groups, and an optical axis for each of the first and second lens groups. Driving means for moving in parallel, imaging means for converting an image formed through the first and second lens groups into an electric signal, and first for determining the position of the focus detection area on the screen. Second area control means, and second for determining the size of the focus detection area
Area control means, extraction means for extracting a focus signal in the focus detection area from the image pickup signal output from the image pickup means, and focus adjustment means for performing focus adjustment based on the extraction means output, The first and second lens groups, the detecting means, the driving means, the focus adjusting means, and the second area control means are provided in the lens unit, and the image pickup means and the first The area control means and the extraction means in the camera body,
While passing the size information of the area output from the area control means from the lens unit to the camera body,
On the camera side, the size information of the delivered area and the output of the extracting means corresponding to the focus detection area determined by the first area control means are delivered to the lens unit. It features an interchangeable lens camera system.

According to a sixth aspect of the present invention, in the fifth aspect, the second area control means is set to the focal length of the first lens group detected by the detection means. Accordingly, the size of the focus detection area is controlled.

According to the invention of claim 7 of the present application, on the camera body side, an extracting means for extracting a focus signal from the image pickup signal corresponding to the focus detection area in the screen, and the focus detection area An area position control means for determining a position in the screen is provided, and on the lens unit side, focus detection means capable of detecting a focus state based on a focus signal output from the extraction means, and based on optical information of the lens unit. Area size control means for determining the size of the focus detection area in the screen, the camera body side determines the position of the focus detection area in the screen, the lens unit side of the focus detection area. An interchangeable lens type camera system configured to determine the size in the screen is featured.

[0023]

According to the first aspect of the present invention, the focus state is detected in the lens unit based on the focus evaluation value transmitted from the camera body, the drive of the focus lens group is controlled, and the area control means is provided. Thus, the size of the focus detection area is determined in the lens unit and delivered to the camera body.

According to the invention described in claim 2, according to claim 1,
In, the size of the focus detection area is changed to an optimum value according to the focal length of the lens unit.

According to the third aspect of the invention, on the camera side, the focus signal in the focus detection area within the screen is extracted from the image pickup signal output from the image pickup means, and the focus detection area is received from the lens unit. The size of the focus detection area is controlled based on the predetermined information indicating the size, and the output of the extraction means corresponding to the determined focus detection area is transmitted to the lens unit.

According to the invention described in claim 4, the setting position of the focus detection area in the screen can be further changed on the camera side.

According to the fifth aspect of the invention, the focus signal in the focus detection area is extracted from the output of the image pickup means on the camera body side and transmitted to the lens unit side. The focus state is detected based on the focus signal transmitted from the focus lens group, the drive of the focus lens group is controlled, and the area control unit determines in the lens unit and delivers it to the camera body. The size of the focus detection area is controlled based on the size information of the focus detection area.

According to the sixth aspect of the present invention, the size of the focus detection area is further changed to the optimum value according to the focal length of the lens unit.

According to the seventh aspect of the invention, the position of the focus detection area in the screen is determined on the camera body side, and the size of the focus detection area in the screen is determined on the lens unit side. Focus detection is performed on the lens unit side based on the focus signal extracted from the focus detection area.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

In the figure, 127 is a lens unit,
Reference numeral 128 denotes a camera body, and the lens unit is detachably attached to the camera body, forming a so-called interchangeable lens system.

The light from the subject is reflected by the lens unit 127.
A fixed first lens group 101, a second lens group 102 (hereinafter referred to as a variable magnification lens) that performs zooming, a diaphragm 103, a fixed third lens group 104, and a focus adjustment function. The CC in the camera body passes through a fourth lens group 105 (hereinafter referred to as a focus lens) that also has a compensator function that corrects the movement of the focal plane due to zooming.
An image is formed on an image pickup device such as D.

The image pickup device in the camera body is provided for each of the three primary colors of red (R), green (G), and blue (B), and is a so-called three-plate type image pickup system.

Of the three primary colors, the red component is imaged on the image sensor 106, the green component is imaged on the image sensor 107, and the blue component is imaged on the image sensor 108.

The images formed on the image pickup devices 106, 107 and 108 are photoelectrically converted into amplifiers 109 and 1, respectively.
After being amplified to the optimum level with 10, 111 respectively,
The signal is input to the camera signal processing circuit 112, converted into a standard television signal and output to a video recorder (not shown), and at the same time, input to the AF signal processing circuit 113.

AF generated by the AF signal processing circuit 113
The evaluation value is read at a cycle of an integral multiple of the vertical synchronizing signal according to the data reading program 115 in the main body microcomputer 114 in the camera body and transferred to the lens microcomputer 116 on the lens unit side.

In the camera signal processing circuit 112, the level of the luminance signal is detected from the image pickup signal output from each image pickup element, and is transferred to the lens microcomputer 116 in the lens unit via the main body microcomputer 114, The iris driver 124 is controlled based on the brightness signal information, the IG meter 123 is driven, and the aperture 103 is controlled to open and close.

The aperture value of the aperture 103 is the encoder 1
It is detected by 29, is supplied to the lens microcomputer 116, and is used as depth of field information.

Further, the main body microcomputer 114 on the camera body side
Indicates the state of the zoom switch 130 and the AF switch (AF operation is performed when ON, and manual focus state is performed when OFF) 131, and the state of the lens microcomputer 116.
Send to.

In the lens microcomputer 116, the AF program 117 receives the state of the zoom switch 130, the state of the AF switch 131 and the AF evaluation value from the main body microcomputer 114, and when the AF switch 131 is on,
Based on this AF evaluation value, the motor control program 118
And the focus motor driver 126 drives the focus motor 125 to move the focus lens 105 in the optical axis direction for focusing.

Further, the zoom motor driver 122 is controlled according to the operation state of the zoom switch 130 to drive the zoom motor 121 and the variable power lens 102 to perform the zoom operation.

The lens microcomputer 116 is the main microcomputer 1
When the AF switch 131 is off and the zoom switch 130 is operated based on the information from 14, the zoom motor driver is used to drive the variable magnification lens in the direction in which the computer zoom program 119 is operated in the tele or wide direction. A signal is sent to 122, the zoom motor 121 is driven, the variable power lens 102 is moved in the operated direction, and a variable power operation is performed.

Since the focal plane is changed by driving the variable power lens 102 during this variable power operation, the focus lens 105 is driven according to a predetermined characteristic as the variable power lens is driven, and the focal plane is changed. The operation of preventing the occurrence of blurring due to the displacement of is performed in parallel.

That is, the computer zoom program 119 in the lens microcomputer 116 is provided with a lens cam data table in which the focus position of the focus lens with respect to the position of the variable power lens is stored for each object distance. The position of the zoom lens and the position of the focus lens are detected by the motor drive amount or encoder, respectively, and the focus locus to be followed by the focus lens during the zooming operation is specified and determined from the lens cam data table. Read out and calculate the correction speed and direction associated with the zoom operation of the focus lens.

When the AF switch 131 is on and the zoom switch is operated, it is necessary to keep the in-focus state. Therefore, the computer zoom program 119 sends the AF evaluation value sent from the main body microcomputer 114. With reference to the signal, the zooming operation is performed while maintaining the position where the AF evaluation value is maximized.

That is, the motor control program 118 drives the focus lens based on the information about the correction speed and direction of the focus lens associated with the zooming operation obtained by the computer zoom program 119 and the AF blur information output from the AF circuit 117. The speed information is added and the total focus lens drive speed and drive direction are calculated and supplied to the focus motor driver 126.

The aperture value of the iris 103 is detected by the encoder 129, supplied to the lens microcomputer 116, and used as depth-of-field information for speed correction of the focus lens.

When the AF switch 131 is ON and the zoom switch 130 is not pressed, the AF program 117 sent from the microcomputer 114 of the main body is the AF program.
A signal is sent to the focus motor driver 126 so that the evaluation value signal becomes maximum, and the focus lens 125 is driven to perform the automatic focus adjustment operation.

The AF signal processing circuit 113 in the camera signal processing circuit 112 will be described with reference to FIG.
The red (R), green (G), and blue (B) image sensor outputs amplified by the amplifiers 108, 109, and 110 to the optimum levels are supplied to the AF signal processing circuit 113, and A / D.
The converters 206, 207 and 208 respectively convert the digital signals to the camera signal processing circuit 112, and at the same time, the amplifiers 209, 210 and 211 respectively amplify the signals to appropriate levels, and the adders 208 add the signals. The focus adjustment luminance signal S5 is generated.

The luminance signal S5 is input to the gamma circuit 213 and is gamma-converted according to a preset gamma curve to produce a signal S6 in which the low luminance component is emphasized and the high luminance component is suppressed. Gamma converted signal S6
Is a low-pass filter with a high cutoff frequency (hereinafter L
TE-LPF 214 which is a PF) and FE-LPF 215 which is an LPF having a low cutoff frequency, and low-frequency components are extracted by the respective filter characteristics determined by the main body microcomputer 114 through the microcomputer interface 253. -LPF 214 output signal S7
And an output signal 8 of the FE-LPF 215 is generated.

The signals S7 and S8 are sent to the switch 216.
Then, it is selectively switched by a Line E / O signal which is a signal for identifying whether the horizontal line is an even number or an odd number, and is input to a high pass filter (hereinafter referred to as HPF) 217.

That is, the signal S7 is supplied to the HPF 217 for even lines and the signal S7 is supplied for odd lines.
8 to the HPF 217.

In the HPF 217, the main microcomputer 114 extracts only the high frequency components by the odd / even filter characteristics determined through the microcomputer interface 253, and the absolute value circuit 218 converts them into absolute values to obtain a positive signal. S9 is generated. That is, S9 is a signal which alternately indicates the levels of the high frequency components extracted by the filters having different filter characteristics on the even lines and the odd lines. As a result, different frequency components can be obtained by scanning one screen.

The signal S9 is supplied to peak hold circuits 225, 226 and 227 for detecting the peak values of the signals in the L frame, C frame and R frame, respectively, and the peaks of the high frequency components in the respective frames. The value is detected and input to the line peak hold circuit 231, and the peak value for each horizontal line is detected.

Here, the frame generation circuit 254, in accordance with a command supplied from the microcomputer 114 via the microcomputer interface 253, has gates L and C frames for focus adjustment at positions on the screen as shown in FIG. , R frame signals are generated.

The peak hold circuit 225 outputs a line signal E for the gate signal L for outputting the L frame output from the frame generation circuit 254 and a signal for identifying whether the horizontal line is an even number or an odd number (a microcomputer). (Generated by 114) is input, and the peak hold circuit 225 is initialized at the position of the upper left LR1 which is the head of the focus adjustment L frame as shown in FIG.
The signal S in each frame of either the even line or the odd line designated from 4 through the microcomputer interface 253
9 is peak-held, and at the lower right IR1, that is, when the scanning of the entire area for focus adjustment is completed, the peak-hold value in the frame is transferred to the area buffer 228 and TE / FE is set.
Generate a peak rating.

Similarly, the C frame output from the frame generation circuit 254 and the Line E / O signal are input to the peak hold circuit 226, and the peak hold is performed by the CR1 on the upper left which is the head of the C frame for focus adjustment shown in FIG. The circuit 226 is initialized and the microcomputer interface 253
The signal S9 in each frame of either the even line or the odd line designated through is peak-held, and at IR1, that is, when the scanning of the entire area for focus adjustment is completed, the peak hold in the frame is held in the area buffer 229. Transfer value T
E / FE peak evaluation value is generated.

Similarly, the peak hold circuit 227 is also provided.
The R frame output from the frame generation circuit 254 and the Line E / O signal are input to the R, and the peak hold circuit 227 is initialized by the upper left RR1 which is the head of the R frame for focus adjustment shown in FIG. The signal S9 in each frame of either the even line or the odd line designated through the microcomputer interface 253 is peak-held, and IR1 is set.
Then, that is, when the scanning of the entire area for focus adjustment is completed, the peak hold value in the frame is transferred to the buffer 230 to generate the TE / FE peak evaluation value.

The line peak hold circuit 231 receives a signal S9 and a gate signal for generating the L frame, C frame, and R frame of the output of the frame generation circuit 254, and is initialized at the horizontal start point in each frame. And the horizontal 1 of the signal S9 in each frame
Hold the peak value of the line.

Integrator circuits 232, 233, 234, 23
5, 236, 237 have a line peak hold circuit 2
31 outputs and a LineE / O signal which is a signal for identifying whether the horizontal line is an even number or an odd number are input to the integration circuits 232 and 235 at the same time as the L frame generation output from the frame generation circuit 254. The gate signal is the integrating circuit 23.
C output from the frame generation circuit output 254 to 3,236.
The gate signal for frame generation is input to the integration circuits 234 and 237 as the gate signal for R frame generation output from the frame generation circuit 254.

The integrator circuit 232 initializes the integrator circuit 232 at the upper left LR1 which is the head of the focus adjustment L frame, and outputs the output of the line peak hold circuit 231 immediately before the end of the even lines in each frame. Add to register, IR
At 1, the peak hold value is transferred to the area buffer 238 to generate the line peak integral evaluation value.

The integrator circuit 233 initializes the integrator circuit 233 at each position of the upper left CR1 which is the head of the focus adjustment C frame, and immediately before the end of the even line in each frame, the line peak hold circuit 231 is initialized. Add the output to the internal register,
At IR1, the peak hold value is transferred to the buffer 239 and the line peak integral evaluation value is generated.

The integrating circuit 234 initializes the integrating circuit 234 with the upper left RR1 which is the head of the focus adjustment R frame, and outputs the output of the line peak hold circuit 231 immediately before the end of the even lines in each frame. IR1
Then, the peak hold value is transferred to the area buffer 240 and the line peak integral evaluation value is generated.

The integrating circuits 235, 236 and 237 respectively add the data of the odd lines instead of adding the data of the even lines 232, 233 and 234, respectively.
Area buffer 2
The result is transferred to 41, 242 and 243.

The signal S7 is the peak hold circuit 21.
9, 220, 221 and line maximum value hold circuit 24
4 and the line minimum value hold circuit 245.

The L-frame generation gate signal output from the frame generation circuit 254 is input to the peak hold circuit 219, and the peak hold circuit 219 is initialized by the upper left LR1 which is the head of the L frame. The signal S7 in the frame is peak-held, the peak-held result is transferred to the buffer 222 by IR1, and the brightness level (hereinafter referred to as the Y signal)
Generate a peak evaluation value of.

Similarly, the peak hold circuit 220 receives the gate signal for C frame generation output from the frame generation circuit 254, and initializes the peak hold circuit 220 with the CR1 at the upper left which is the head of the C frame. , Signal S in each frame
7, the peak hold result is transferred to the buffer 223 by IR1, and the Y signal peak evaluation value is generated.

Further, similarly, the peak hold circuit 221
Receives the gate signal for R frame generation output from the frame generation circuit 254, initializes the peak hold circuit 221 at the upper left RR1 which is the head of the R frame, and peak holds the signal S7 in each frame. Then, at IR1, the buffer 22
The peak hold result is transferred to 4 and a Y signal peak evaluation value is generated.

The line maximum value hold circuit 244 and the line minimum value hold circuit 245 receive the gate signals for L frame, C frame, and R frame generation output from the frame generation circuit 254, respectively, and the horizontal lines in each frame. It is initialized at the start point of the direction, and holds the maximum value and the minimum value of the Y signal of one horizontal line of the signal S7 in each frame.

These line maximum value hold circuits 244
And the line minimum value hold circuit 245 holds the maximum and minimum values of the Y signal held by the subtracter 246.
Is input to the peak hold circuits 247, 248, and 249, and the (maximum value-minimum value) signal, that is, the signal S10 representing contrast is calculated.

A gate signal for L frame generation is input from the frame generation circuit 254 to the peak hold circuit 247, and the peak hold circuit 247 is operated at the upper left LR1 which is the head of the L frame.
Is initialized, the signal S10 in each frame is peak-held, the peak-hold result is transferred to the buffer 250 by IR1, and the Max-Min evaluation value is generated.

Similarly, the peak hold circuit 248 receives a gate signal for C frame generation from the frame generation circuit 254,
The peak hold circuit 248 is initialized by CR1 at the top left of the C frame, the signal S10 in each frame is peak-held, the peak hold result is transferred to IR1, the buffer 251, and the Max-Min value is generated. To do.

Similarly, the peak hold circuit 249 receives a gate signal for R frame generation from the frame generation circuit 254, and the peak hold circuit 249 is initialized by the upper left RR1 which is the head of the R frame. Signal S10 in the frame
Is peak-held, the peak-hold result is transferred to the buffer 252 by IR1, and the Max-Min evaluation value is generated.

At the time of IR1 when the scanning of the entire area for focus detection consisting of the L frame, the C frame, and the R frame is completed, the buffers 222, 223, 224, 228, 229, and 23 respectively.
0,238,239,240,241,242,24
At the same time that the data in each frame is transferred to 3,250, 251, 252, at the same time, an interrupt signal is sent from the frame generation circuit 254 to the microcomputer 114 to transfer the data transferred in each buffer to the microcomputer 114. And transfer processing.

That is, the microcomputer 114 receives the interrupt signal and, through the microcomputer interface 253, the buffers 222, 223, 224, 228, 229, 2
30,238,239,240,241,242,24
Each data in 3,250,251,252 is converted to the next L
The scanning in the frame, the C frame, and the R frame is completed until the next data is transferred to each buffer, and the data is read and transferred to the lens microcomputer 116 in synchronization with the vertical sync signal as described later.

The lens microcomputer 116 calculates these focus evaluation values, detects the focus state, calculates the focus motor drive speed and drive direction, and controls the focus motor to drive the focus lens.

Here, the timing of fetching various information in the AF signal processing circuit 113 will be described with reference to the layout of each area for focus detection in the screen of FIG. The outer frame is an effective image pickup screen output from the image pickup devices 106, 107, and 108.

The inner three-divided frame is a focus detection gate frame, and the left L frame, the central C frame, and the right R frame are each L frame generation gate signals output from the frame generation circuit 254. C
It is formed according to the frame generation gate signal and the R frame generation gate signal.

Then, reset signals are output for each of the L, C, and R frames at the start positions of these L, C, and R frames, and initialization (reset) signals LR1, CR1, and RR1 are output.
Are generated, and the integration circuits 232 to 237 and the peak hold circuits 219 to 221, 225 to 227, 247 to 249 are generated.
Etc. are reset.

A data transfer signal IR1 is generated at the end of scanning the focus detection area consisting of L, C, and R frames, and the integrated value of each integrator circuit and the peak hold value of each peak hold circuit are transferred to each buffer. .

Scanning of even fields is indicated by a solid line and scanning of odd fields is indicated by a dotted line. In both even and odd fields, the even line selects the TE-LPF output and the odd line selects the FE-LPF output.

Next, a method of setting the generation positions of the reset signals LR1, CR1, RR1 and the data transfer signal IR1 generation position for each of the L, C, and R frames will be described with reference to FIGS.

In the present embodiment, the size and position of the distance measuring frames L, C and R can be changed, the set position is determined by the camera body, and the size is determined by the lens unit. ing.

In FIG. 1, the distance measuring frame position setting device 135 in the camera body 128 is a device for designating where the main subject desired to be photographed is on the screen,
For example, even with an input device such as a joystick, a trackball, or a mouse, it is possible to use a line-of-sight input device that detects the gazing point at which the photographer looks into the image pickup screen in the viewfinder, so that the position on the screen can be specified. Anything is fine.

A signal from the distance measurement frame position setting device 135 is used by the distance measurement frame position detection / setting circuit 136 to display position coordinates within the screen (point 401 = (x,
y) and sends it to the ranging frame control unit 137 in the main body microcomputer 114 as the center coordinate of the ranging frame.

The size of the distance measuring frame is determined by the lens microcomputer 1
The size information is determined by the ranging frame size control unit 120 in 16 and the size information (FIG. 4: horizontal width a, vertical width b of each ranging frame).
Is sent to the ranging frame control unit 137 in the main body microcomputer 114.

The distance measuring frame control unit 137 detects the distance measuring frame city.
As shown in FIG. 4, the coordinates in the screen of LR1, CR1, RR1, and IR1 are determined from the center position information and size information of the distance measuring frame obtained from the setting circuit 136 and the distance measuring frame size control unit 120. , The gate circuit 254 of the AF signal processing circuit 113
To control the distance measuring frames L, C, R.

Here, the size of the distance measuring frame can be changed on the side of the lens unit in order to suppress the influence of the camera screen or camera shake on the image pickup screen according to the change of the focal length of the lens, and to determine what kind of lens This is because stable AF performance is achieved even when is attached.

If the frame size is set to a fixed size on the camera body, the more the telephoto lens of higher magnification is mounted, the larger the subject image in the range-finding frame becomes.
The image contrast disappears and the subject image in the frame moves violently due to the influence of camera shake or the like, resulting in unstable AF operation.

It is also possible to pass the focal length information from the lens unit to the camera side and control the frame size on the camera side. However, when the frame size changes, the integrated evaluation value of the AF evaluation value changes in level and the AF control is performed. If the frame size is not changed in accordance with the above, the AF malfunction will be caused, and the communication between the lens unit and the camera body regarding the evaluation value and the frame switching will be very complicated.

For the above reasons, the lens microcomputer 11
6 determines the optimum distance measurement frame size for AF stabilization according to the characteristics of each lens, such as setting the distance measurement frame size larger as the angle of view becomes more telephoto, and sends the frame size information to the camera body. hand over.

Further, a case where there is an electronic zoom function for changing the magnification of an image by image processing will be described. The video signal processed by the camera signal processing circuit 112 in FIG. 1 is stored in the field memory 132, and while reading the image stored in the interpolation circuit 133, vertical enlargement and horizontal expansion are performed while performing interpolation between scanning lines and between pixels. Output the enlarged signal.

The enlarged signal output is again subjected to color processing and the like in the camera signal processing section and converted into a standard TV signal.

The interpolation circuit 133 controls according to the enlargement ratio information from the electronic zoom control section 134 in the main body microcomputer 114.

The electronic zoom magnification rate information from 134 is sent to the lens microcomputer 116, and the distance measurement frame size control section 120 in the 116 performs the focal length conversion of the image pickup screen, and according to the reset focal length. Controls the range frame size.

Next, the TE / FE peak evaluation value in each frame, T
The following describes how the microcomputer performs the automatic focus adjustment operation using the E line peak integral evaluation value, the FE line peak integral evaluation value, the Y signal peak evaluation value, and the Max-Min evaluation value. Incidentally, these evaluation values are transmitted to the lens microcomputer 116 in the lens unit, and the actual control is performed by the lens microcomputer 116.

The TE / FE peak evaluation value is an evaluation value representing the degree of focus, and is a peak hold value, so it is relatively independent of the subject and less affected by camera shake and the like, and is most suitable for determination of the degree of focus and restart. .

The TE line peak integral evaluation value and the FE line peak integral evaluation value also represent the degree of focus, but they are stable evaluation values with little noise due to the integration effect, and are therefore optimal for direction determination.

Further, both the peak evaluation value and the line peak integral evaluation value are optimal near the in-focus state because the high frequency components of TE are extracted, and conversely, the FE is optimal during large blur far from the in-focus state. . Therefore, add these signals,
Alternatively, by selectively switching and using according to the level of TE, it is possible to perform AF with a wide dynamic range from large blurring to near the focal point.

Also, the Y signal peak evaluation value and Max-Min
Since the evaluation value does not depend much on the degree of focus and depends on the subject, it is ideal for grasping changes in the subject, movements, etc. in order to make sure focus determination, restart determination, and direction determination. is there. The focus evaluation value is also used for normalization to remove the influence of the change in brightness.

That is, the Y signal peak evaluation value is used to determine whether the object is a high-luminance object or a low-illuminance object, the Max-Min evaluation value is used to determine the contrast, and the TE / FE peak evaluation value and the TE line peak integration evaluation value are determined. , By predicting and correcting the peak size of the FE line peak integrated evaluation value, optimum AF control can be performed.

These evaluation values are transferred from the camera body 128 to the lens unit 127, and the lens unit 12
It is supplied to the lens microcomputer 116 in 7 and the automatic focus adjustment operation is performed.

The algorithm of the automatic focus adjustment operation in the lens microcomputer 116 in the lens unit 127 will be described with reference to FIG.

When the processing is started, the AF operation is first activated in the processing of step 1, then the processing proceeds to step 2, and the level of the TE or FE peak is compared with a predetermined threshold value, thereby making a large blur. The speed control is performed by determining whether the focus is near the focus or how far from the focus.

At this time, when the TE level is low and it is expected to be a foot of a mountain, that is, a large blur, the FE line peak integral evaluation value is mainly used to control the direction to focus the focus lens. Mountain climbing control, and when the TE level rises to a certain extent near the top of the mountain, the focus lens is mountain climbing controlled using the TE line peak integral evaluation value so that the focal point can be detected with high accuracy. .

Next, when it comes near the in-focus point, step
Going to the process of 3, the peak of the mountain is judged by the absolute value of the TE or FE peak evaluation value or the amount of change of the TE line peak integral evaluation value, and the highest evaluation level is obtained at the top of the mountain, that is, the focal point. If it is determined to be a point, the focus lens is stopped in step 4, and the process of step 5 enters the restart standby.

In the restart waiting, when it is detected that the level of the TE or FE peak evaluation value is lower than the peak value when the in-focus point is detected by a predetermined level or more, the process is restarted in step 6.

By repeating the above processing, the AF operation can always be performed. In the loop of this automatic focus adjustment operation, the degree of speed control using the TE / FE peak, the absolute level of the mountain peak judgment, the amount of change in the TE line peak integral evaluation value, the Y peak evaluation value, M
The size of the mountain is predicted from the subject determination using the ax-Min evaluation value, and the determination is performed based on this.

In the first aspect, the focus adjusting means is
Lens microcomputer 116, focus motor driver 12
6, the focus motor 125, the area control means corresponds to the distance measurement frame size control section 120 in the lens microcomputer 116, and the communication means from the lens microcomputer 116 to the distance measurement frame control section 137 in the camera side main body microcomputer 114. Corresponds to a means for communicating information on the size of the distance measurement frame.

Further, in claim 3, the image pickup means corresponds to the image pickup elements 106, 107 and 108, the extraction means corresponds to the AF signal processing circuit 113 in the camera signal processing circuit 112, and the area control means corresponds to the main body microcomputer 114. In the AF signal processing circuit 113, the transmission unit corresponds to the data reading unit 115 in the main body microcomputer 114 that transmits the focus evaluation value corresponding to the focus detection area to the lens unit. .

The area position control means corresponds to the distance measuring frame position setting device 135 and the distance measuring frame position detecting / setting circuit 136 in the camera body.

In the fifth aspect, the first lens group corresponds to the variable power lens 102, the second lens group corresponds to the focus lens 105, and the detecting means is the variable power lens 102.
And the function of the lens microcomputer 116 that detects the position of the focus lens 105 by counting motor drive pulses and the like, the drive means correspond to the zoom motor 121 and the focus motor 125, respectively, and the image pickup means corresponds to the image pickup elements 106, 107 ,. 108, the first area control means corresponds to the distance measurement frame position setting device 135 and the distance measurement frame position detection / setting circuit 136 in the camera body, and the second area control means corresponds to the measurement area in the lens microcomputer 116. Distance frame size control unit 120
The extraction means corresponds to A in the camera signal processing circuit 112.
It corresponds to the F signal processing circuit 113.

In claim 7, the extraction means corresponds to the AF signal processing circuit 113 in the camera signal processing circuit 112, and the area position control means is the distance measuring frame position setting device 135 and the distance measuring frame position detection in the camera body. It corresponds to the setting circuit 136, the focus detection means corresponds to the lens microcomputer 116 in the lens unit, and the area size control means corresponds to the distance measurement frame size control unit 120 in the lens microcomputer 116.

[0114]

As described above, according to the first aspect of the present invention, the focus state is detected in the lens unit based on the focus evaluation value transmitted from the camera body, and the focus lens group is detected. Is controlled, and the size of the focus detection area is determined in the lens unit by the area control means and passed to the camera body. Therefore, the position of the focus detection area is controlled by the body and the focus detection area is adjusted according to the focal length. By controlling the size of the focus detection area with the lens unit, it is possible to set the optimum size of the focus detection area according to the characteristics of each mounted lens and the function of the camera such as the electronic zoom function. Even if such a lens is attached, or different cameras are connected to the same lens,
It is possible to provide an interchangeable lens system that can stably focus on a target main subject under all subjects and shooting conditions.

According to the second aspect of the present invention, the size of the focus detection area is changed to an optimum value in accordance with the focal length of the lens unit, so that the zoom operation is always performed. The optimum focused state can be maintained with high accuracy.

Further, even when an ultra-high-magnification lens is attached, or even when it is magnified to a high-magnification by electronic zoom, an interchangeable lens system that maintains stable AF performance regardless of the change in focal length due to zooming is realized. Is possible.

According to the third aspect of the present invention, on the camera side, the focus signal in the focus detection area within the screen is extracted from the image pickup signal output from the image pickup means, and the focus signal received from the lens unit is received. The size of the focus detection area is controlled by predetermined information indicating the size of the detection area, and the output of the extraction means corresponding to the determined focus detection area is transmitted to the lens unit, so that the lens unit is mounted. Since the focus detection area of the optimum size can be set according to the characteristics of each lens and the function of the camera such as the electronic zoom function,
It is possible to provide an interchangeable lens system that can stably focus on a target main subject regardless of what kind of lens is attached or different cameras are connected to the same lens, regardless of the subject or shooting conditions. Becomes

According to the invention of claim 4 of the present application, since the setting position of the focus detection area in the screen can be changed on the camera side, a case where an ultra-high magnification lens is mounted, It is possible to realize an interchangeable lens system that maintains stable AF performance regardless of a change in focal length due to zooming even when the image is enlarged to a high magnification by electronic zoom.

According to the fifth aspect of the present invention, the focus signal in the focus detection area is transmitted from the camera body side to the lens unit side, and the focus signal transmitted from the camera body is transmitted in the lens unit. Based on this, the focus state is detected, the drive of the focus lens group is controlled, and in the lens unit is determined by the area control means and passed to the camera body. On the camera body side, the size of this focus detection area is determined. Since the size of the focus detection area is controlled based on this information, the focus detection area with the optimum size can be selected according to the characteristics of each lens to be mounted and the functions of the camera such as the electronic zoom function. Because you can set it, no matter what kind of lens is attached or if different cameras are connected to the same lens, the target main subject will be used for all subjects and shooting conditions. As can be stably focus, we are possible to provide interchangeable lens system.

According to the sixth aspect of the present invention, the size of the focus detection area is further changed to an optimum value in accordance with the focal length of the lens unit. It is possible to realize an interchangeable lens system that maintains stable AF performance regardless of a change in focal length due to zooming even when the image is enlarged to a high magnification by electronic zoom.

According to the invention described in claim 7, the position of the focus detection area in the screen is determined on the camera body side, and the size of the focus detection area in the screen is determined on the lens unit side. Based on the focus signal extracted from the focus detection area, focus detection is performed on the lens unit side, so it is optimal depending on the characteristics of each mounted lens, depending on the camera function such as the electronic zoom function. Since a focus detection area of various sizes can be set, no matter what kind of lens is attached or different cameras are connected to the same lens, stable focusing on the target main subject under all subjects and shooting conditions is possible. It becomes possible to provide such an interchangeable lens system.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of an embodiment of an automatic focus adjustment device of the present invention.

FIG. 2 is a block diagram showing an internal configuration of an AF signal processing circuit on the camera body side in the automatic focusing apparatus shown in FIG.

FIG. 3 is a diagram for explaining an extraction operation and extraction timing of various focus evaluation values according to the present invention.

FIG. 4 is a diagram for explaining a size and position setting operation of the distance measurement frame in the embodiment of the present invention.

FIG. 5: A performed in the lens microcomputer 116 of the present invention
It is a flow chart for explaining F operation.

FIG. 6 is a block diagram showing a typical configuration of a conventional automatic focus adjustment device.

[Explanation of symbols]

 105 Focus Lens 106 Image Sensor 107 Image Sensor 108 Image Sensor 112 Camera Signal Processing Circuit 113 AF Signal Processing Circuit 114 (Camera) Main Unit Microcomputer 116 Lens Microcomputer 117 AF Control Circuit 118 Motor Control Circuit 120 Distance Measuring Frame Size Control Unit 125 Focus Motor 126 Focus motor driver 135 Distance measuring frame position setting device 136 Distance measuring frame position detection / setting circuit 137 Distance measuring frame control unit

Claims (7)

[Claims] 1. A lens unit detachable from a camera body, wherein the focus lens group is used for focus adjustment, and the focus lens group is driven based on a focus evaluation value transmitted from the camera body. Focus adjustment means, area control means for determining the size of the focus detection area in the screen, communication means for delivering the size information of the focus detection area determined by the area control means to the camera body,
A lens unit characterized by having. 2. The lens unit according to claim 1, wherein the area control means is configured to change the size of the focus detection area according to the focal length of the lens unit. 3. A camera in which a lens unit can be exchanged, the image pickup means converting an image formed through the lens unit into an electric signal, and an image picked up from the image pickup signal outputted from the image pickup means. Extraction means for extracting the focus signal in the focus detection area, area control means for receiving the predetermined information indicating the size of the focus detection area from the lens unit and controlling the size of the focus detection area, An interchangeable lens type camera comprising: a transmission unit that transmits the output of the extraction unit corresponding to the focus detection area determined by the area control unit to the lens unit. 4. The camera according to claim 3, further comprising area position control means for changing a setting position of the focus detection area in the screen. 5. An interchangeable lens type camera system capable of exchanging a lens unit with respect to a camera body, wherein a lens unit side is provided with a first lens group for zooming and a second lens group for performing focus adjustment. A lens group; a detection means for detecting the positions of the first and second lens groups; a drive means for independently moving the first and second lens groups in parallel with the optical axis; An image pickup means for converting an image formed through the first and second lens groups into an electric signal; a first area control means for determining the position of the focus detection area in the screen; and a size of the focus detection area. Second area control means for determining the depth, extraction means for extracting a focus signal in the focus detection area from the image pickup signal output by the image pickup means, and focus adjustment based on the output of the extraction means Point adjustment means, the first and second lens groups, the detection means, the drive means, the focus adjustment means, and the second area control means are provided in the lens unit, The image pickup means, the first area control means, and the extraction means are provided in the camera body, and the size information of the area output from the second area control means is transferred from the lens unit to the camera body. At the same time, on the camera side, the output of the extracting means corresponding to the size information of the delivered area and the focus detection area determined by the first area control means is delivered to the lens unit. An interchangeable lens type camera system characterized by being configured. 6. The size of the focus detection area according to claim 5, wherein the second area control means controls the size of the focus detection area according to the focal length of the first lens group detected by the detection means. The interchangeable lens type camera system is characterized by being configured as follows. 7. On the camera body side, an extracting means for extracting a focus signal from an image pickup signal corresponding to a focus detection area in the screen, and an area position control means for determining the position of the focus detection area in the screen. The lens unit side, the focus detection means capable of detecting the focus state based on the focus signal output from the extraction means, and the size of the focus detection area in the screen based on the optical information of the lens unit. And an area size control unit for determining the position of the focus detection area in the screen on the camera body side, and the size of the focus detection area in the screen on the lens unit side. An interchangeable lens type camera system characterized by the above.