JPH099130A - Automatic focusing device - 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: An AF signal processing circuit 113 at a camera side uses a filter to extract a focus evaluation signal from an image pickup signal equivalent to a signal in one or plural focus detection areas in an image, the extracted focus signal is sent to a lens microcomputer 116 at a lens unit side, the lens microcomputer 116 decides a drive direction and a drive speed of a focusing lens toward a focal point based on the increase/decrease in a level of the received focus evaluation signal to drive the focusing lens.

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. Extraction means for extracting a signal, control means for determining a drive direction and drive speed for driving the focus lens of the optical system to the in-focus point based on increase or decrease in the level of the output signal of the extraction means, and the control means for controlling the drive direction and drive speed. Drive means for driving a focus lens, the extracting means is arranged on the camera side, the control means and the driving means are arranged in a lens unit, and the output of the extracting means is directed from the camera side to the lens unit side. The focus lens is driven by handing over the focus lens.

According to a second aspect of the present invention, in the first aspect, the extracting means is selected from among the image pickup signals corresponding to the focus detection area in the image pickup signal as the focus signal. It is configured to include a plurality of filter means for extracting the signal of the frequency component.

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. It is configured to include means for performing.

According to a fourth aspect of the present invention, in the second aspect, the extraction means further comprises means for detecting a contrast component of the image pickup signal corresponding to the focus detection area. .

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 of the present application, an extracting means for extracting a focus signal from the image pickup signals corresponding to one or a plurality of focus detection areas in the screen,
An automatic focus permission switch that permits automatic focus adjustment operation,
When the automatic focus permission switch is in the permission state, control means for deciding a driving direction and a driving speed for driving the focus lens of the optical system to the in-focus point on the basis of increase and decrease of the level of the output signal of the extraction means, and the control means. Drive means for driving the focus lens based on the output of the extraction means, the extraction means and the automatic focus permission switch are arranged on the camera side, the control means and the drive means are arranged in a lens unit, and the extraction is performed. The focus lens is driven by passing the output of the means and the state of the automatic focus permission switch to the lens unit.

According to the invention described in claim 7 of the present application, an extracting means for extracting a focus signal from the image pickup signals corresponding to one or a plurality of focus detection areas in the screen,
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 the increase or decrease of the level of the output signal of the extraction 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 driving means are arranged in a lens unit, and the focus signal output from the extraction means is synchronized with an integer multiple of a vertical synchronization signal. It is configured to be delivered to the lens unit.

According to the invention of claim 8 in the present application, there is provided a lens unit which is attachable to and detachable from the camera body having the focus detecting means, and which receives means for receiving the focus evaluation value transmitted from the camera side. A control unit that determines a focus state based on a focus evaluation value received by the receiving unit and calculates and determines a focus lens driving speed and a driving direction; and a focus lens based on a calculation result of the control unit. The driving means for driving is provided.

Further, according to the invention of claim 9 in the present application, there is provided a lens unit which is attachable to and detachable from the camera body having the focus detecting means, and which receives the focus evaluation value transmitted from the camera side. The focus lens driving speed and the focus lens driving speed are calculated by calculating the correction information for determining the focus state based on the focus evaluation value received by the receiving unit and correcting the movement of the focal plane position due to the zooming operation. A configuration is provided that includes a control unit that calculates and determines the drive direction and a drive unit that drives the focus lens based on the calculation result of the control unit.

According to the tenth aspect of the present invention, in the camera in which the lens unit is attachable / detachable, the focus signal is selected from the image pickup signals corresponding to one or a plurality of focus detection areas in the screen. By providing an extracting means for extracting and a communication means for transmitting the output signal of the extracting means to the microcomputer in the lens unit, the driving direction and the driving speed for driving the focus lens to the focal point on the lens unit side. Is calculated.

[0021]

According to the first aspect of the invention, the signal used as the focus evaluation value corresponding to the inside of the focus detection area extracted by the extracting means is transferred to the lens unit side to be stored in the lens unit. The control means determines the drive speed and drive direction of the focus lens of the optical system.

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

According to the invention of claim 6, in addition to the structure of claim 1 described above, by passing the state of the automatic focus permission switch to the lens as well, the control means is provided in the body even though it is in the lens. Be controllable.

According to the invention of claim 7, in addition to the configuration of claim 1, the lens can be exchanged by sending the extraction means to the lens unit in synchronization with an integral multiple of the vertical synchronization signal. Nevertheless, an accurate automatic focus adjustment operation can be realized.

According to the eighth aspect of the present invention, the signal used as the focus evaluation value corresponding to the inside of the focus detection area extracted by the extracting means is transferred to the lens unit side, and the signal in the lens unit is transferred. The control means determines the drive speed and drive direction of the focus lens of the optical system.

According to the present invention, the displacement of the focal plane due to the AF operation and the zooming operation is simultaneously corrected in the lens unit.

According to the tenth aspect of the invention, the focus evaluation value is transmitted to the 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. It

[0028]

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, 108 are photoelectrically converted into amplifiers 109, 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 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.

Further, the motor driver 122 is controlled according to the operating state of the zoom switch 130 to control the zoom motor 12
1 is driven and the zoom lens 102 is driven to perform the zoom operation.

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 storing the focus position of the focus lens with respect to the position of the zoom lens for each object 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 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 and the Line E / O signal output from the frame generation circuit 254 are input to the peak hold circuit 226, and the peak hold is performed by the 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 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 by 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 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 at 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, 237 respectively add the data of the odd lines instead of adding the data of the even lines 232, 233, 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 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 horizontally within 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, a gate signal for R frame generation is input from the frame generation circuit 254 to the peak hold circuit 249, 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 at which 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 focusing lens. .

Here, the timing of fetching various kinds of information in the AF signal processing circuit 113 will be described using the diagram showing 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 line selects the TE-LPF output and the odd line selects 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.

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 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. However, 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 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.

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 levels of the TE and FE peaks are compared with a predetermined threshold value to obtain 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 in step 6.

By repeating the above processing, the AF operation can be always 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.

FIG. 5 is a diagram for explaining the timing of communication of various data including the AF evaluation value from the body microcomputer 114 on the camera body 128 side to the lens microcomputer 116 in the lens unit 127. As described above, the communication timing between the camera body 128 and the lens unit 127 is set immediately after the vertical synchronization signal by synchronizing the AF evaluation value read by the body microcomputer 114 with the next vertical synchronization signal (V synchronization). To the lens microcomputer 116.

As a result, the AF operation can be controlled in synchronization with the vertical synchronizing signal.

In the above embodiment, the AF signal processing circuit 113 in the camera signal processing circuit 112 corresponds to the extracting means, and the lens microcomputer 116 in the lens unit drives the focus lens to the focal point and the driving direction. It corresponds to the control means for determining the speed.

Data communication from the microcomputer 114 in the camera body to the lens microcomputer 116 in the lens unit corresponds to a means for delivering the output of the extracting means from the camera side to the lens unit side.

In addition, TE-L in the AF signal processing circuit 113
The PF 214, FE-LPF 215, and HPF 217 correspond to a plurality of filter means.

Further, the peak hold circuits 219, 220,
Reference numeral 221 corresponds to a means for detecting a peak hold output obtained by peak-holding the luminance component of the image pickup signal corresponding to the focus detection area.

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.

Further, the peak hold circuits 247, 248,
Reference numeral 249 corresponds to peak holding means for detecting a contrast component.

Further, the computer zoom program 119 and the lens cam data 12 without the lens microcomputer 116.
0 corresponds to a unit that calculates correction information for correcting the movement of the focal plane position due to the zooming operation.

[0100]

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? It is possible to provide an automatic focus adjustment device that can determine the optimum response and the like for each lens even when the lens is attached, and that can stably focus on a target main subject under all subjects and shooting conditions.

Further, according to the inventions of claims 2 to 5, the specific frequency component, the peak value of the luminance 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 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.

According to the invention of claim 6, in addition to the structure of claim 1, the state of the automatic focus permission switch is also handed over to the lens unit side, so that the control means is on the lens unit side. In other words, the interchangeable lens system described above can be realized without being deteriorated in operability because it can be controlled by the camera body.

According to the invention of claim 7, in addition to the configuration of claim 1, the lens can be exchanged by sending the extraction means to the lens unit in synchronization with an integral multiple of the vertical synchronizing signal. Nevertheless, it is possible to realize an accurate automatic focus adjustment device capable of stably focusing on the intended main subject under all subjects and shooting conditions.

According to the invention described in claims 8 and 9,
By having a function on the lens unit side that controls the focus plane shift due to the control of automatic focus adjustment or zooming operation, it is possible to determine the optimum response etc. It is possible to provide an automatic focus adjustment device capable of stably focusing on a target main subject depending on the subject and shooting conditions.

According to the tenth aspect of the invention, the focus evaluation value is transmitted to the lens unit side, and the driving speed and the driving direction of the focus lens are determined by the control means in the lens unit. Therefore, it is possible to provide an automatic focus adjustment device that can determine the optimal response etc. for each lens regardless of which lens is attached and can stably focus on the target main subject under all subjects and shooting conditions. Become.

[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 showing a communication timing of an AF evaluation value to a lens unit in the 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

Claims (10)

[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 in a screen, and a focus lens of an optical system based on increase / decrease in level of the output signal of the extracting means. A driving means for driving the focus lens based on the control means; and a driving means for driving the focusing lens based on the control means. An automatic focusing apparatus, characterized in that the driving means is arranged in a lens unit, and the output of the extracting means is passed from the camera side to the lens unit side to drive the focus lens. . 2. The extracting means according to claim 1, wherein the extracting means includes a plurality of filter means for extracting 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. An automatic focus adjustment device characterized by being provided. 3. The automatic extracting device according to claim 2, wherein the extracting means further includes means for detecting a peak hold output obtained by peak-holding a luminance component of an image pickup signal corresponding to the focus detection area. Focus adjustment device. 4. The automatic focus adjustment device according to claim 2, wherein the extraction means further comprises means for detecting a contrast component of an image pickup signal corresponding to the focus detection area. 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. An extracting 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 automatic focus permission switch for permitting an automatic focus adjustment operation.
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 on the basis of increase / decrease in the level of the output signal of the extraction means when the automatic focus permission switch is in the permitted state; Drive means for driving the focus lens based on the output of the extraction means, the extraction means and the automatic focus permission switch are arranged on the camera side, the control means and the drive means are arranged in a lens unit, and the extraction is performed. An automatic focus adjusting device for driving the focus lens by delivering the output of the means and the state of the automatic focus permission switch to the lens unit. 7. An extracting 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 a focus lens of an optical system based on increase / decrease in level of the output signal of the extracting means. A driving means for driving the focus lens based on the control means; and a driving means for driving the focusing lens based on the control means. The automatic focus adjusting device is characterized in that the driving means is arranged in a lens unit, and the focus signal output from the extracting means is delivered to the lens unit at a timing synchronized with an integral multiple of a vertical synchronization signal. . 8. A lens unit attachable to and detachable from a camera body having a focus detecting means, the receiving means receiving a focus evaluation value transmitted from a camera side, and the focus evaluation value received by the receiving means. And a drive unit that drives the focus lens based on the calculation result of the control unit. The lens unit to be used. 9. A lens unit attachable to and detachable from a camera body having a focus detecting means, the receiving means receiving a focus evaluation value transmitted from a camera side, and the focus evaluation value received by the receiving means. While determining the focus state based on, the control means for calculating and determining the focus lens drive speed and drive direction by calculating the correction information for correcting the movement of the focal plane position due to the zooming operation, A lens unit comprising: a driving unit that drives the focus lens based on a calculation result of the control unit. 10. A camera with a detachable lens unit, the extracting 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 signal of the extracting means. And a communication means for transmitting to the microcomputer in the lens unit so that the driving direction and the driving speed for driving the focus lens to the focal point can be calculated on the lens unit side.