JPH099132A - Automatic focusing device and camera - Google Patents

Abstract

PURPOSE: To provide an automatic focusing device capable of being focused stably with every major object under any image pickup condition even when any lens is mounted onto an interchangeable lens system video camera. CONSTITUTION: This automatic focusing device is provided with an AF signal processing circuit 113 extracting focus signal from an image pickup signal equivalent to a signal within a focus detection area, a normalizing program 132 normalizing an output of the AF signal processing circuit 113, and a lens microcomputer 116 deciding the drive direction and the speed of a focus lens based on the normalized focus signal, the AF signal processing circuit 113 and the normalized program are provided to the camera and the lens microcomputer 116 is arranged in the lens unit, and the output of the AF signal processing circuit 113 is given from the camera side to the lens unit to drive the focus lens in the automatic focusing device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic focus adjusting device suitable for use in a video camera or the like in which a lens unit can be exchanged.

[0002]

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

Such an automatic focus adjustment system does not require a special optical member for focus adjustment for detecting emission / reception of infrared rays or an image shift amount which changes according to a focus state, and it is possible to use a long distance. It has the advantage of being able to focus accurately regardless of the distance even in the vicinity.

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

In the figure, reference numeral 501 denotes a focus lens, which is moved by a lens driving motor 511 in the optical axis direction for focusing. The light passing through this lens is imaged on the image pickup surface of the image pickup device 502, photoelectrically converted into an electric signal, and output as a video signal. This video signal is sampled and held by the CDS / AGC 503, then amplified to a predetermined level, converted to digital video data by the A / D converter 504, input to a process circuit of a camera (not shown), and then supplied to a standard television. A bandpass filter (hereinafter BPF) 505
Is input to.

The BPF 505 extracts the high frequency component from the video signal, the gate circuit 506 extracts only the signal corresponding to the portion set in the focus detection area in the screen, and the peak hold circuit 507 extracts the integer of the vertical synchronizing signal. The peak hold is performed at an interval synchronized with the double, and an AF evaluation value is generated.

This AF evaluation value is taken into the AF microcomputer 508 of the camera body, and the AF microcomputer 50 of the camera body
8, the focus motor drive speed according to the focus degree, and
Determine the motor drive direction so that the AF evaluation value increases,
The drive speed and drive direction of the focus motor are transmitted to the lens microcomputer 509 in the lens unit.

The lens microcomputer 509 is the A of the camera body.
Focus control is performed by driving the focus lens 501 in the optical axis direction by the focus motor 511 via the motor driver 510 as instructed by the F microcomputer 508.

[0009]

However, in the above-mentioned conventional example, since the lenses can be exchanged, the control of the automatic focus adjustment is provided on the camera body side, so that the automatic focus adjustment is optimized for a specific lens. Once the responsiveness is determined, it may not be optimal for other lenses, and it has been difficult to obtain optimal performance for all removable lenses.

Therefore, an object of the present invention is to solve the above-mentioned problems and provide an automatic focus adjusting device which stably focuses on a target main subject regardless of the type of lens attached and under all subjects and shooting conditions. Especially.

[0011]

In order to solve the above-mentioned problems, according to the invention described in claim 1 of the present application, the focus is higher in the image pickup signal corresponding to one or more focus detection areas in the screen. Extracting means for extracting a signal; normalizing means for normalizing the output of the extracting means; and a driving direction and a driving speed for driving the focus lens of the optical system to a focal point based on the increase or decrease of the level of the output signal of the extracting means. And a drive means for driving the focus lens based on the control means, the extraction means is arranged on the camera side, the control means and the drive means are arranged in a lens unit, The focus lens is driven by passing the output of the extraction means from the camera side to the lens unit side.

According to a second aspect of the present invention, in the first aspect, the extracting means is more specific than the image pickup signal corresponding to the focus detection area in the image pickup signal as the focus signal. A plurality of filter means for extracting the signal of the frequency component are provided, and the normalizing means ensures that the specific frequency components extracted by the filter means are the same when a specific subject is photographed. Configured to normalize.

According to a third aspect of the present invention, in the second aspect, the extraction means further detects a peak hold output obtained by peak-holding the luminance component of the image pickup signal corresponding to the focus detection area. Is equipped with
The normalizing means is configured to normalize the peak hold output to be the same when a specific subject is photographed.

Further, according to the invention of claim 4 in the present application, in claim 2, the extracting means further comprises means for detecting a contrast component of an image pickup signal corresponding to the inside of the focus detection area, and the standard. The converting unit is configured to normalize the contrast component so that it becomes the same when a specific subject is photographed.

According to a fifth aspect of the present invention, in the fourth aspect, the extraction means peak-holds the difference between the maximum value and the minimum value of the luminance component in the focus detection area. The configuration is such that peak holding means for detecting the contrast component is provided.

According to the invention of claim 6 in the present application, a camera in which the lens unit is attachable / detachable,
Extraction means for extracting the focus signal from the image pickup signal corresponding to one or more focus detection areas on the screen, standardization means for standardizing the output of the extraction means, and standardization by the standardization means It is possible to calculate the driving direction and the driving speed for driving the focus lens to the focal point on the lens unit side by providing the communication unit that transmits the output signal of the extracted extraction unit to the microcomputer in the lens unit. And the configuration.

[0017]

According to the first aspect of the present invention, the signal used as the focus evaluation value corresponding to the focus detection area extracted by the extracting means is normalized by the normalizing means, and then the lens. It is transferred to the unit side, and the drive speed and drive direction of the focus lens of the optical system are determined by the control means in the lens unit.

According to the second to fifth aspects of the present invention, the specific frequency component, the peak value of the brightness component, and the contrast component in the image pickup signal are used as the evaluation value of the focus state, respectively, and the focus detection with higher precision is performed. It can be performed.

According to the invention of claim 6, on the camera side, the signal used as the focus evaluation value corresponding to the inside of the focus detection area extracted by the extracting means is standardized by the normalizing means. The image is transferred to the rear lens unit side, and the drive speed and drive direction of the focus lens of the optical system are determined by the control means in the lens unit.

With this, it is possible to stably focus on a target subject under any subject and shooting conditions by any image pickup means.

[0021]

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 for performing zooming, a diaphragm 103, a fixed third lens group 104, a focus adjustment function, and movement of a focal plane due to zooming. Pass through a fourth lens group 105 (hereinafter referred to as a focus lens) that also has a correction function for correction,
An image is formed on an image pickup device such as a CCD in the camera body.

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, standardized by the evaluation value standardizing program 132, and the lens on the lens unit side It is transferred to the microcomputer 116. Evaluation value standardization program 132
The contents of will be described later.

In the camera signal processing circuit 112, the level of the brightness signal is detected from the image pickup signal output from each image pickup device, 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 main 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 causes the AF switch 1 from the main body microcomputer 114.
When the state of No. 31 and the AF evaluation value are received, and the AF switch 131 is on, the motor control program 118 is operated based on this AF evaluation value, the focus motor driver 126 drives the focus motor 125, and the focus lens 105 is driven. Focusing is performed by moving in the optical axis direction.

The motor driver 122 is controlled according to the operating state of the zoom switch 130 to control the zoom motor 12
The zoom operation is performed by driving 1 to 9 degrees and driving the zoom lens 102.

On the other hand, when the lens unit is of the inner focus type, the focal plane is changed by driving the zoom lens 102, so that the focus lens 105 has a predetermined characteristic as the zoom lens is driven. Therefore, the operation of driving and preventing the occurrence of blurring due to the displacement of the focal plane is performed in parallel.

The lens cam data 120 in the lens microcomputer 116 is a ROM that stores the focus position of the focus lens with respect to the position of the zoom lens for each subject distance.
With the computer zoom control program 119,
The position of the zoom lens and the position of the focus lens are respectively detected by the drive amount of the motor or the encoder, and the focusing locus to be followed by the focus lens during the zoom operation is specified and read out from the ROM 120 to perform the zoom operation of the focus lens. Calculate the correction speed and direction associated with.

The information on the correction speed and the direction is added to the blur information of the AF output from the AF circuit 117 by the motor control program 118 to calculate the total focus lens drive speed and drive direction, and the motor driver. Is supplied to 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.

Next, the camera signal processing circuit 11 will be described with reference to FIG.
The AF signal processing circuit 113 in 2 will be described. The red (R), green (G), and blue (B) image pickup device outputs amplified by the amplifiers 108, 109, and 110 to the optimum levels are supplied to the AF signal processing circuit 113, and the A / D converter. At 206, 207 and 208, they are converted into digital signals respectively and sent to the camera signal processing circuit 112, and at the same time, they are respectively amplified to appropriate levels by amplifiers 209, 210 and 211 and added by an adder 208 for automatic focus adjustment. The luminance signal S5 for use 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 the even lines and the signal S7 is supplied for the odd lines.
8 to the HPF 217.

In the HPF 217, the main microcomputer 114 extracts only the high frequency component by the odd / even filter characteristics determined through the microcomputer interface 253, and the absolute value circuit 218 converts it into an absolute value 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 gate signal L for outputting the L frame output from the frame generation circuit 254 and a line E / O signal (microcomputer) for identifying whether the horizontal line is an even number or an odd number. (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 CR1 at 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 CR1 at the upper left, which is the head of the focus adjustment C frame, and immediately before the end of the even line in each frame, the integration of the line peak hold circuit 231 is performed. 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 sent to 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 gate signal for L frame generation 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 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.

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 the 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 including 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 drives the focus motor to drive the focusing lens. .

The timing of fetching various kinds of information in the AF signal processing circuit 113 will be described below 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, a reset signal is 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 integration 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 lines select the TE-LPF output and the odd lines select the FE-LPF output.

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.

Here, the characteristics and uses of each evaluation value will be described.

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 optimal 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 point because high frequency components of TE are extracted, and conversely, FE is optimal during large blur far from the in-focus point. . 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.

The Y signal peak evaluation value and the 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 used. , 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.

An algorithm of the automatic focusing 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 to make 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 at the foot of a mountain, that is, a large blur, the FE line peak integral evaluation value is mainly used to control the direction to perform focusing. When the lens is climbed and controlled, and the level of TE rises to a certain extent when reaching the top of the mountain, T
The focusing lens is climbed and controlled using the E-line peak integral evaluation value so that the in-focus 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 by the process of 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.

Next, the evaluation value standardization 132 will be described with reference to FIG. This figure shows a change in the TE peak evaluation value when a certain subject is photographed and the lens is searched from the closest distance to infinity.

(A1) and (a2) of FIG. 5 are values read by the data reading program 115 when the subject and the lens are the same and the images are taken by different cameras (imaging means).

Although the subject and the lens have the same conditions, the output levels are different. Evaluation value standardization program 1
At 32, the levels are determined so that the signal levels at the two points P1 and P2 become predetermined values, and the overall signal level is shifted, compressed, or expanded in accordance with the levels.

Evaluation value standardization program 132 of (a1)
The output is (a2), the output of the evaluation value standardization program 132 in (b1) is (b2), and the input level of the evaluation value standardization program 132 is different between (a1) and (a2). , (A2) and (b2) have almost the same output level. Evaluation value standardization program 13
2 also performs the same standardization for other evaluation values.

That is, the evaluation value standardization program 132
Is a TE peak value in the L frame, C frame, and R frame output from the buffers 228 to 230 in FIG. 2, and an integrated value of the TE peak in the L frame, C frame, and R frame output from the buffers 238 to 243. 5 (a), the integrated value of the FE peak and the peak value of the contrast in the L frame, C frame, and R frame output from the buffers 250 to 252 are input, and the peak value of the input signal level is compressed or expanded.
2) and (b2), the maximum value level shift processing for forcibly adjusting to the level of P1 and the compression or expansion of the minimum value of the input signal level are performed, and P of FIGS.
The minimum value level shift processing for forcibly adjusting to the level 2 is performed (FIG. 5 shows the TE peak, but the other evaluation values described above are similarly standardized to the lens microcomputer 116. Sent).

As a result, even if the image pickup elements 106 to 108 and the AF signal processing circuit 113 vary within the camera body, the focus evaluation values all show the same mountain-shaped characteristics, and the maximum and minimum values are the same. Even if a plurality of camera units having different image pickup means and a plurality of different lens units are combined without causing a variation in value, it becomes possible to pass a common output to the lens by standardizing the focus signal. Since optimum responsiveness and the like can be determined for each lens unit within the lens unit, it is possible to stably focus on the target main subject under all subjects and shooting conditions.

The extracting means corresponds to the AF signal processing circuit 113 in the camera signal processing circuit 112, and the normalizing means is the main body microcomputer 114 in the camera body.
The control means corresponding to the evaluation value standardization program within the lens unit 116 in the lens unit determines the drive direction and drive speed for driving the focus lens to the in-focus point.
The drive means corresponds to the motor driver 126 and the focus motor 125, and the means for delivering the output of the extraction means from the camera side to the lens unit side is the microcomputer 114 in the camera body to the lens microcomputer 116 in the lens unit. Equivalent to data communication to.

Further, according to claim 2, the TE-LPF 214, the FE-LPF 215, in the AF signal processing circuit 113.
The HPF 217 corresponds to a plurality of filter means.

Further, in claim 3, the peak hold circuits 219, 220, 221 correspond to means for detecting a peak hold output by peak-holding the luminance component of the image pickup signal corresponding to the focus detection area.

Further, in claim 4, the line maximum value hold circuit 244, the line minimum value hold circuit 245, and the subtractor 246 correspond to means for detecting the contrast component of the image pickup signal corresponding to the focus detection area.

In the fifth aspect, the peak hold circuits 247, 248, 249 correspond to peak hold means for detecting the contrast component.

Further, in claim 6, the extracting means corresponds to the AF signal processing circuit 113 in the camera signal processing circuit 112, and the normalizing means is the main body microcomputer 114 in the camera main body.
Corresponding to the evaluation value standardizing program in the above, and the means for delivering the output of the extracting means from the camera side to the lens unit side corresponds to data communication from the microcomputer 114 in the camera body to the lens microcomputer 116 in the lens unit. .

[0096]

As described above, according to the invention described in claim 1 of the present application, what kind of lens can be obtained by passing the focus signal to the lens unit and having automatic focus adjustment control on the lens unit side? Even if you attach the lens, you can determine the optimal response etc. for each lens, and even if you combine multiple camera units with different imaging means and multiple different lens units, standardize the focus signal to obtain a common output Since it is possible to determine the optimum responsiveness and the like within each lens unit for each lens unit, it is possible to stably focus on a target main subject under all subjects and shooting conditions.

Further, according to the inventions of claims 2 to 5, a specific frequency component, a peak value of a brightness component, and a contrast component in the image pickup signal are used as the evaluation value of the focus state, respectively, and the focus detection with higher precision It is possible to perform, and by using a plurality of focus state evaluation values, it is possible to correspond to various characteristics and functions of the lens side,
A system with high versatility can be realized. Further, by standardizing each evaluation value, it is possible to stably focus on the target main subject under all subjects and shooting conditions without being affected by variations on the camera side.

According to the sixth aspect of the invention, the focus signal is passed to the lens unit and the automatic focus adjustment control is provided on the lens unit side. It is possible to determine common responsiveness, etc., and even if a plurality of cameras with different image pickup means and a plurality of different lens units are combined, a common output can be passed to the lens by standardizing the focus signal. The optimum responsiveness and the like can be determined within the range, and the target main subject can be stably focused on all subjects and shooting conditions.

[Brief description of 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 flow chart for explaining an AF operation in the embodiment of the present invention.

FIG. 5 is a diagram for explaining a process of an evaluation value standardizing program 132 which constitutes a standardizing means in the exemplary embodiment of the present invention.

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 125 Focus Motor 126 Motor Driver 132 Standardization of Evaluation Value program

Claims (6)

[Claims] 1. An extracting means for extracting a focus signal from an image pickup signal corresponding to one or a plurality of focus detection areas on a screen, a normalizing means for normalizing an output of the extracting means, and the extracting means. A control means for determining a drive direction and a drive speed for driving the focus lens of the optical system to the in-focus point based on increase and decrease of the level of the output signal; and a drive means for driving the focus lens based on the control means. Driving the focus lens by arranging the extracting means on the camera side, arranging the control means and the driving means in the lens unit, and passing the output of the extracting means from the camera side to the lens unit side. An automatic focus adjusting device characterized in that 2. The plurality of filter means according to claim 1, wherein the extraction means extracts a signal of a specific frequency component from an image pickup signal corresponding to the focus detection area in the image pickup signal as the focus signal. The normalizing means is configured to normalize the specific frequency components extracted by the filter means to be the same when a specific subject is photographed. Automatic focus adjustment device. 3. The extracting means according to claim 2, further comprising means for detecting a peak hold output obtained by peak-holding a luminance component of the image pickup signal corresponding to the focus detection area, and the normalizing means for the peak. An automatic focus adjusting device, characterized in that the hold output is configured so as to be equalized when a specific subject is photographed. 4. The extracting means according to claim 2, further comprising means for detecting a contrast component of an image pickup signal corresponding to the inside of the focus detection area, and the normalizing means wherein the contrast component is a specific subject. An automatic focus adjustment device, which is configured to normalize so as to be the same when shooting. 5. The extraction means according to claim 4, further comprising peak holding means for detecting the contrast component by peak-holding a difference between the maximum value and the minimum value of the brightness component in the focus detection area. An automatic focus adjustment device characterized in that 6. A camera having a detachable lens unit, the extraction means for extracting a focus signal from an image pickup signal corresponding to one or a plurality of focus detection areas in a screen, and an output of the extraction means. The focus lens is provided on the lens unit side by providing the normalizing means for normalizing and the communication means for transmitting the output signal of the extracting means standardized by the normalizing means to the microcomputer in the lens unit. A camera capable of calculating a driving direction and a driving speed for driving the lens to a focal point.