JP2504499B2 - Focus adjustment method and apparatus for television camera - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a focus adjustment method and apparatus for a television camera, and more specifically, when a drama is recorded in a broadcasting studio or the like, A focus adjustment method for a TV camera that is configured to automatically perform fine adjustment of the focus of the shooting optical system of the TV camera for the instructed subject according to an instruction from a person who is watching a viewfinder or monitor television. And equipment.

[Conventional technology]

In recent years, high-definition television systems have been developed and are in the stage of practical application, and inevitably high precision focusing is required.

However, in the conventional TV camera, the focus lens of the photographing optical system of the TV camera is manually operated while looking into the viewfinder to focus on the subject. In this case, the visual limit resolution of the image on the viewfinder depends on the size of the viewfinder, but is about 400 to 500 TVL, which is 1000 TVL required for a high-definition television system.
It is difficult to perform focusing so as to sufficiently satisfy the degree of resolution.

Therefore, in order to support high-definition television systems, until now, when focusing the shooting optical system of the TV camera, focusing while looking through the viewfinder so that an image with a resolution of at least about 1000 TVL can be obtained. In addition to the cameraman who operates the camera, there is a focus man who manually adjusts the focus while observing a separately prepared large monitor, and entrusts the person with fine focus adjustment.

On the other hand, a TV that can focus the shooting optical system of the TV camera on the subject specified by the instruction of the viewfinder of the TV camera or the viewer of the monitor during shooting. Realization of a camera is desired.

For example, suppose that a drama for television broadcasting is recorded in a broadcasting studio. In this case, as a matter of course, not only the actors and actresses who are the characters of the drama but also the director who is the director, the TV cameraman who is in charge of the shooting, and the focus man mentioned above are the recording of the drama. I will be involved in shooting.

Generally, a viewfinder is attached to the TV camera operated by the TV cameraman, and the subject image displayed by the TV cameraman is displayed on this screen.

However, this viewfinder is relatively small (for example, 7 inches), and it is difficult to determine whether or not the subject image projected on the viewfinder is properly focused.

Therefore, the same subject image as the subject image displayed on the viewfinder is displayed on a large monitor television, and the monitor television observes the monitor television. Then, he / she decides by himself and finely adjusts the focusing, or works such as where to focus on the same screen according to the instruction of the director.

[Problems to be solved by the invention]

FIG. 12 shows the relationship between the aperture value and the depth of focus with the resolution as a parameter. As mentioned above, for example
When focusing by manual operation while looking through the viewfinder, which is the limit resolution of 400TVL, the focus adjustment is performed within the area of 400TVL resolution surrounded by the curves A and A'in FIG. , Because this area is within the depth of focus at this resolution, no longer for the manual operator,
It becomes unclear which side of the area is located.

Therefore, in focusing while looking through a viewfinder of about 1.5 to 7 inches with a resolution of about 400 TVL,
Adjustment is difficult within the range of 1000 TVL resolution surrounded by the curves B and B'required in a high definition television system.

Also, during broadcasting, it is practical to select the above position by moving from the short-distance side to the long-distance side and from the long-distance side to the short-distance side again with respect to the position where the best imaging performance is obtained during manual operation. This is impossible because the image becomes blurred and the image shakes, which is unsightly.

Despite this situation, to adjust the focus so that a good resolution of about 1000 TVL can be obtained,
At least the target focus value is 1000TV indicated by curves C and C '.
It must be set within the depth of focus range of 1/2 of the depth of focus at the resolution of L.

By the way, it is assumed that a scene as shown in FIG. 9 is displayed on the viewfinder.

That is, the person 103 is projected in the front center of the screen made up of the CRT 101 that constitutes the viewfinder 100, the tree 105 is projected at a rear position slightly apart to the left, and further to the right on the far side. House 104 is shown.

In the screen shown in FIG. 9, it is assumed that the TV cameraman has focused on the person 103 in the foreground, and the director wants to focus on the tree 105 on the left.

In such a case, the director's authority is given the highest priority in the production of Dora, and this director instructs the focus man to focus on the tree 105.

In other words, the cameraman, the focus man, and the director play their respective roles in the recording of a conventional TV camera, and the director's intention of where to focus on the screen is realized on the screen through the focus man, and the director's intention is It was not directly displayed on the screen. That is, in the conventional video recording of a TV drama, a focus man is required in addition to the TV cameraman, and it is difficult to express the intention of the director directly on the screen.

Generally, the focus position of the television camera is set on a window 102 (shown by diagonal lines) formed in the approximate center of the CRT 101 as shown in FIG.

The present invention has been made in view of the above circumstances, and provides a photographing optical system of a television camera for a subject designated based on an instruction from a viewfinder of a television camera or a director watching a monitor television. To provide a focus adjustment method and device for a television camera capable of performing focus adjustment of a focus lens and fine adjustment of focus adjustment of a focus lens with respect to a high spatial frequency component which is difficult to visually judge. It is intended.

[Means for solving problems]

In the focus adjustment method for a television camera of the present invention, in order to achieve the above object, a photographing optical system including a focus lens for focusing on a subject and a subject image formed by the photographing optical system are converted into video signals. Image pickup means, signal processing means for converting the video signal into a video signal of a predetermined format, viewfinder for receiving the video signal from the signal processing means and displaying a subject on a monitor, and a screen displayed on the viewfinder Focusing area designating means for designating an area to be focused by the photographing optical system using
A manual focusing unit that moves the focus lens in the optical axis direction to perform focusing based on a manual operation of the operating member, and an area designated by the focusing area designating unit in the video signal from the signal processing unit. A high spatial frequency component is extracted from a video signal showing the image, and the manual focusing means is operated by moving the focus lens in the optical axis direction so that the integrated value of the extracted high spatial frequency component becomes a maximum value. In a focus adjusting method for a television camera having an automatic focusing means for performing focusing with higher focusing accuracy, a state in which the focusing by the automatic focusing means is stopped and the focusing by the manual focusing means is possible. To the standard state,
A fine adjustment mode is provided in which focusing by the manual focusing means is stopped and focusing by the automatic focusing means is performed.
When the focusing in the standard state is performed and the focusing in the standard state is completed, the focusing in the fine adjustment mode is performed, and when the focusing in the fine adjustment mode is completed, the standard state is automatically restored. It is characterized by having done.

In order to achieve the above-mentioned object, the focus adjustment device for a television camera of the present invention uses a photographing optical system including a focus lens for focusing on a subject and a subject image formed by the photographing optical system as a video signal. An image pickup means for converting, a signal processing means for converting the video signal into a video signal of a predetermined format, a viewfinder for receiving a video signal from the signal processing means and displaying a subject image on a monitor, and a display on the viewfinder. A focusing area designating means for designating an area to be focused by the photographing optical system using the selected screen, and a video signal output from the signal processing means in response to an output signal of the focusing area designating means. Based on the focus position fixing means for extracting only the video signal showing the image of the area on the screen of the specified viewfinder, and the manual operation of the operating member. A manual focusing means for focusing by moving the focus lens in the optical axis direction, and a high spatial frequency component is extracted from the output signal from the focusing position determining means, and the integrated high spatial frequency component is integrated. The focusing lens is moved in the optical axis direction so that the value becomes a maximum value, and the automatic focusing means for focusing with higher focusing accuracy than the manual focusing means, and the focusing by the automatic focusing means. A state in which the focus can be stopped by the manual focusing means is set as a standard state, and a fine adjustment mode in which the focusing by the manual focusing means is stopped and the focusing by the automatic focusing means is performed is provided. When the focusing is performed and the focusing in the standard state is finished, the focusing in the fine adjustment mode is performed, and the focusing in the fine adjustment mode is finished. It is characterized in that it has a control means for controlling so as to automatically return to the normal state.

[Action]

In the focus adjustment method of the television camera according to the present invention, the focus adjustment of the photographing optical system is performed by the manual focusing means with respect to the subject in the designated area on the screen of the viewfinder that displays the subject image on the monitor.

After adjusting the focus of the photographic optical system by this manual focusing means,
Fine adjustment of the focusing of the photographing optical system with respect to the high spatial frequency component which is difficult to be visually judged by the automatic focusing means which operates in response to the start signal generated based on the completion of the focusing operation of the manual focusing means or the external manual operation. Adjustments are made.

In the focus adjustment device for a television camera according to the present invention, when the focus area designation means designates the area on the screen of the viewfinder where the photographing optical system should be focused, the focus position determination means outputs the signal from the signal processing means. Only the video signal showing the image of the area on the screen of the viewfinder designated by the focus area designating means is extracted from the video signals. At the same time, the photographic optical system of the television camera is focused on the subject by the manual focusing means.

Next, the focus lens is moved a plurality of times at a predetermined time interval by a predetermined movement amount by an automatic focusing means that operates by receiving an activation signal generated based on the end of driving of the focus lens by the manual focusing means or a manual operation. As described above, the driving means is controlled, the focus amounts at the respective moving positions are calculated based on the output signal of the focusing position determining means, and the position where the best imaging performance of the focus lens is obtained is determined. The focus lens is moved to that position. As a result, the photographing optical system of the TV camera can be focused on the object specified based on the instruction from the viewfinder of the TV camera or the director watching the monitor TV, and the visual judgment is difficult. Fine adjustment of focusing of the focus lens with respect to various high spatial frequency components is performed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the appearance of a television camera to which the present invention is applied. As shown in FIG. 1, a viewfinder 2 including a CRT or the like is attached to the front side of a television camera body 1. .

The screen of this viewfinder 2 is divided into four parts in the vertical direction and five parts in the horizontal direction at substantially equal intervals, and the number 1 which is the identification name of each section is provided in the upper right corner of each section. 2 ......... 20 is attached.

Further, FIG. 2 shows the configuration of a main point adjusting device for a television camera according to the present invention. In the figure, the photographing optical system 3 is composed of a focus lens 10, a zoom lens 12, a master lens 13, an aperture 14, and the like. The focus lens 10 is a lens for focusing the photographing optical system.

The focus lens 10 is driven by an actuator 16 such as a motor or a piezoelectric element in the direction of the optical axis 90 of the photographing optical system 1 via a driving mechanism (not shown).

The actuator 16 is given a drive signal by the drive circuit 18, and the control circuit 50 outputs a control signal for driving the actuator 16 via the D / A converter 20 to the drive circuit 18.

The zoom lens 12 is a lens system that changes the magnification of the photographing optical system 1, and is composed of various lenses. The zoom position (magnification) of the zoom lens 12 is detected by a potentiometer 29 linked to a zoom ring (not shown),
The detected value is input to the control circuit 50 via the A / D converter 31.

The aperture value that is set is detected by a potentiometer 28 that works in conjunction with an aperture ring (not shown) that varies the aperture area of the aperture 14, and the detected value is transmitted via the A / D converter 30 to the control circuit 5
It is supposed to be input to 0.

15 is a color separation optical system, and this color separation optical system 15 is a diaphragm
It is an optical component that separates the light incident via 14 into the three primary colors of R, G, and B, and is composed of, for example, a dichroic prism and a filter.

37, 38, 39 are R, G, and
An image pickup device constituted by an image pickup tube or a solid-state image pickup device for converting an optical image of a subject by light separated into the three primary colors of B into a video signal, and these image pickup devices 37, 38,
The weak video signals obtained by the 39
After being amplified by 40, 41, 42, process circuits 43, 44,
Entered in 45.

The process circuits 43, 44 and 45 are respectively preamplifier 40 and
This is a circuit that performs various signal processing such as frequency characteristic compensation, gamma correction, and edge enhancement on the video signals output from 41 and 42 to generate video signals of the three primary colors R, G, and B.

The color encoder 46 outputs the R, G and B video signals output from the process circuits 43, 44 and 45 in a predetermined format,
For example, it is a circuit that produces a composite video signal of the NTSC system.

The sync separation circuit 48 outputs the composite video signal output from the color encoder 46 to the focus position selection analog gate 52 via the high-pass filter 51, and also outputs the composite video signal from the composite sync signal SYNC, the horizontal sync signal Hsync, and the vertical sync. This is a circuit that separates the signal Vsync and supplies each of these synchronization signals to each circuit unit.

The high-pass filter 51 has a frequency characteristic that allows only a signal component near the high frequency of the signal band of the video signal to pass. That is, the cutoff frequency of the high-pass filter 51 is selected near the high frequency of the signal band of the video signal.

By the way, the taking optical system of the television camera can be understood as a function as a low-pass filter for a video signal showing a subject image when considering the response characteristic with respect to the spatial frequency. In this way, when the photographing optical system is considered as a low-pass filter, the cutoff frequency of the frequency characteristic of the low-pass filter greatly changes depending on the defocus amount.

On the other hand, since the high frequency component contained in the video signal indicates the definition of the subject image, the amplitude information of the high frequency component of the video signal in the vicinity of the cutoff frequency of the low pass filter is used as information for focus adjustment of the photographing optical system of the television camera. Can be used. Therefore, the cutoff frequency of the high-pass filter 51 is selected near the high frequency of the signal band of the video signal.

The mixing circuit 47 includes the video signal output from the color encoder 46 and the CRT controller 4 controlled by the control circuit 50.
It is a circuit that mixes the signal transmitted by 9 and composed of the division of the screen of the viewfinder 2 and the number (1, 2, 3, ..., And the like) which is its identification name.

The video signal mixed by the mixing circuit 47 is input to the video drive circuit 3 forming the viewfinder 2, and the subject image is displayed on the screen of the CRT 2a forming the viewfinder 2.

Reference numeral 32 denotes an operation member for driving the focus lens 10 by manual operation, and when the operation member 32 is turned, the operation member 32 is rotated by a potentiometer 34 which is interlocked with the operation member 32.
A voltage corresponding to the amount of rotation of is detected, and the detected voltage value is input to the control circuit 50 via the A / D converter 36.

An external start button 33 generates an external start signal for instructing the control circuit 50 to perform automatic focus adjustment of the focus lens 10.

On the other hand, Mamelaman 9 has a microphone 27 attached to his head in the form of headphones.
27 is connected to the voice identification unit 60.

That is, the microphone 27 is connected to an analog interface 61 which constitutes a voice recognition unit 60 and which compresses a wide bandwidth voice signal into a digital signal, and the output end of the analog interface 61 is a pre-registered voice. It is connected to an arithmetic processor 62 that compares the voice input from the analog interface 61.

The arithmetic processor 62 is connected to a registration memory 63 in which voice is registered in advance and a system control unit 64 which controls the voice recognition unit.

In the registration memory 63, the divisions of the CRT 2a of the viewfinder 2 are registered in advance as voices (names) such as “1”, “2”, ... However, a predetermined signal corresponding to the number 5 is generated by the identification number (for example, "5") of the voice uttered later by the cameraman 9.

This voice recognition unit 60 is dedicated to the cameraman 9, and if voices are registered in advance with a director (not shown), another voice recognition unit dedicated to the director is used. It may be prepared and registered separately.

The output end of the system control unit 64 that constitutes the voice recognition unit 60 is connected to the control circuit 50.

The focus position selection analog gate 52 is a circuit for extracting a video signal of only a specified section on the screen of the CRT 2a in the viewfinder 2, and the focus position selection analog gate 52 is supplied from the sync separation circuit 48 to the horizontal sync signal. Hsync, vertical sync signal Vsync, Vstart signal, Ven from control circuit 50
The d signal, the Hstart signal, and the Hend signal are supplied.

Therefore, the video signal obtained from the color encoder 46 is input to the high-pass filter 51 via the sync separation circuit 48, and only the high-frequency component of the video signal is extracted by the high-pass filter 51. The high frequency component of this video signal is input to the focus position selection analog gate 52, and the analog gate 52 further extracts the video signal of only the section specified on the screen of the CRT 2a of the viewfinder 2.
It is output to the A / D converter 53.

Also, from the focus position selection analog gate 52, the A / D converter 5
3, a timing signal is output to the RAM 54, the address generator 55, and the control circuit 50. With this timing signal, the A / D conversion processing of the A / D converter 53, the RAM 54
Each timing for writing / reading data to / from the RAM and outputting the address data from the address generator 55 to the RAM 54 is determined.

The video signal of the section determined by the analog gate 52 is A /
A / D converted by the D converter 53, the amplitude information of the high frequency component of the A / D converted video signal is written in the RAM 54 and input to the control circuit 50 as necessary.

The control circuit 50 takes in signals from the A / D converters 30, 31, 36, RAM 54, the voice recognition unit 60, etc., and performs various arithmetic processes,
CRT2 of viewfinder 2 is used as the shooting optical system of the TV camera.
The drive control of the actuator 16 is performed to adjust the focus of the focus lens 10 so as to focus on the subject belonging to the designated section on the screen in a.

The operation of the focus adjustment device for a television camera having the above configuration will be described below.

First, as shown in FIG. 2, when the TV cameraman 9 points the TV camera at the person 103 and operates the operation member 32,
The subject image of the person 103 is a photographing optical system 3 and a color separation optical system 1.
5. The image is displayed on the screen of the CRT 2a constituting the viewfinder 2 via the image pickup devices 37, 38, 39 and the like.

 This state is shown in FIG.

At this time, if the TV photographer wants to focus on the person 103, the identification name which is the 18th division is "18".
Recite.

Then, this voice is supplied to the analog interface 61 via the microphone 27, is converted into a digital signal here, and the registered content is compared with the registered memory 63 via the arithmetic processor 62.

Here, the voice signal of "18" described above is stored in advance in the registered memory.
If it is registered in 63, a predetermined signal is sent to the system control unit.
It is sent from 64 to the control circuit 50. Even if another person other than the photographer chanted the above "18",
Since this voice signal is not registered in the registration memory 63,
The above-mentioned predetermined signal is not output. That is, the voice recognition unit 60 generates a predetermined signal according to only the voice of the cameraman 9.

Then, in this control circuit 50, the coordinates on the CRT 2a sung by the TV cameraman are calculated and determined.

Then, while looking through a viewfinder (not shown), the operation member 32 is operated to focus the photographing optical system of the television camera on the subject. A voltage value corresponding to the operation amount (rotation amount) of the operation member 32 is detected by the potentiometer 34 and input to the control circuit 50 via the A / D converter 36. The control circuit 50 controls the D / A based on the digital signal from the A / D converter 36.
A control signal for driving the actuator 16 in a predetermined direction by a predetermined amount according to the operation of the operation member 32 is output to the drive circuit 18 via the converter 20. As a result, the actuator 16
Receives the drive signal from the drive circuit 18 and the focus lens 10
Is moved on the optical axis 90 via a drive mechanism (not shown). In this way, the focusing of the photographing optical system of the television camera is adjusted by manually operating the operation member 32.

Now, the manual operation of the operation member 32 described above ends (stops).
Then, the fine adjustment of focusing is automatically performed by the activation signal based on the end of the focusing operation. As described above, this fine adjustment changes the equivalent bandwidth for a subject at a certain distance by focusing when the shooting optical system is considered as a low-pass filter, and the high-frequency component of the video signal near the cut-off frequency of this low-pass filter. Since the amplitude changes significantly, the amplitude change is detected, and the amplitude of the high frequency component becomes maximum at the focus position. Therefore, the focus lens 10 is moved so that this amplitude becomes maximum.

FIG. 10 shows the relationship (focus amount curve) between the amount of defocus of the focus lens 10 (hereinafter referred to as the defocus amount) and the amplitude of the high-frequency component of the video signal obtained through the high-pass filter 51. In the figure, it can be understood that the inclination and the maximum value (peak) of the focus amount curve differ depending on the aperture value AV. The ROM provided in the control circuit 50 stores the relationship between the aperture value and the movement amount of the focus lens 10 as a table.

Now, from the potentiometer 28 linked to the aperture ring,
The aperture value is taken into the control circuit 50 via the D converter 30,
The control circuit 50 determines the moving amount and moving direction of the focus lens 10 based on the aperture value, and outputs a control signal for minutely moving the actuator 16 to the drive circuit 18 via the D / A converter 20. This control signal is performed for each field, and the integrated value of the high frequency component of the video signal of four points (one of which is used for the direction determination) having different defocus amounts in two frames is written in the RAM 54 by the control circuit 50. The maximum value (peak) of the focus amount curve is calculated from the relationship between the integrated value and the defocus amount, which is calculated from the amplitude information of the high frequency component
The coordinate value of the defocus amount that obtains The contents of this arithmetic processing will be described with reference to FIG.

In FIG. 11, the focus lens 10 is slightly moved,
The focus voltage values of the high frequency components of the video signals at the three points a, b and c are obtained. In the figure, x is the defocus amount, and y is the focus voltage value of the high frequency component of the video signal obtained through the high pass filter 51. When the distance between a, b, and c is S and the x coordinate of point a is “0”, the coordinates of each point are: a (0, y _A ) …… (1) b (S, y _B ) …… (2 ) C (2S, y _C ) ... (3).

Summit _P (x P, y P) of the curve passing through the three points determined using an interpolation polynomial of Lagrange the x-coordinate x _P of.

The formula P (x) of the focus amount curve passing through the three points of a (x ₀ , y ₀ ), b (x ₁ , y ₁ ), and c (x ₂ , y ₂ ) is expressed as follows.

Substituting equations (1), (2), and (3) into equation (5), Substituting equations (6), (7) and (8) into equation (4) When the differential expression of P (x) is 0, it takes a maximum value. Therefore, the distance x _P from the point a to the in-focus position _P is given by the equation (9).

The control circuit 50 obtains the movement amount of the focus lens 10 from the data indicating the coordinate value X _P, and sends a control signal for moving the focus lens 10 to the in-focus position to the drive circuit 18 via the D / A converter 20. Output. As a result, a drive signal is output from the drive circuit 18 to the actuator 16, the focus lens 10 is moved to the in-focus position with respect to the subject, and remains at that position until a start signal is input by the next manual operation or the like. .

However, in the series of focusing operations described above, the maximum value of the focus amount curve may not be determined. In that case, a control signal for focusing on the subject is output from the control circuit 50 to the actuator 16 via the D / A converter 20 and the drive circuit 18. After that, arithmetic processing is performed again for obtaining the coordinates of the maximum value of the focus amount curve, and as a result of the similar drive control of the focus lens 10, it is difficult to obtain the photographing optical system of the television camera by manual operation for the subject. Focused with high accuracy.

In this way, the focus area (division) on the screen of the CRT 2a of the viewfinder 2 is designated and the focus of the focus lens 10 is manually adjusted.

Next, the contents of the processing routine executed by the control circuit 50 are shown in FIGS. 3A and 3B. In these figures, when this processing routine is activated, the focus area is designated by voice input to the microphone 28 as described above, and the control circuit 50 calculates the coordinates on the CRT 2a (step 200).

Next, at step 201, it is judged whether or not the designation of the focus area is completed, and if the designation of the focus area is not completed, the same judgment is repeated.

When the designation of the focus area is completed, that is, when the focus area is determined by the calculation by the control circuit 50, only the high frequency component of the video signal output from the color encoder 46 is extracted by the high pass filter 51.
Further, the focus position selection analog gate 52 selects the CRT2 specified in the video signal output from the high-pass filter 51.
Only the signal component indicating the focus area on the screen of a is taken out, and this signal is A / D converted by the A / D converter 53,
The amplitude information of the high frequency component of the A / D converted video signal is R
Written to AM54.

Next, the current position of the operating member 32 for focusing the focus lens 10 by manual operation is the potentiometer.
Detected by 34, read through A / D converter 36,
The data is written in the storage unit (RAM) in the control circuit 50 (step 202). Next, the aperture value of the aperture 14 set by the aperture ring (not shown) is the potentiometer 28 and the A / D converter 3
Zoom position (magnification) of the zoom lens 12 via 0
Are read via the potentiometer 29 and the A / D converter 31, respectively, and written in the storage section in the control circuit 50 (step 203).

Furthermore, whether or not the current position of the operating member 32 has changed from the position read in step 202 and the operation of the operating member 32 has stopped, in other words, whether the focus lens 10 has been manually focused and has ended. It is determined whether or not (step 204). Focus lens 10 operated manually
If focus has been taken and is finished, step 20
Go to 5. In addition, a manual focus lens 10
If the focusing is not performed, the process proceeds to step 210, and it is determined whether the external start button 33 has been operated.

When it is determined in step 210 that the external start button 33 has not been operated, the process returns to step 202. External start button 3
When 3 is operated, the process proceeds to step 205. In this way, when the focusing of the focus lens 10 by the manual operation is completed or the external start button 33 is operated by the processing of steps 202 to 204 and step 210, step 20
Fine adjustment of focusing of the focus lens 10 is performed in steps 5 to 209 and steps 211 to 221.

In step 205, the focus lens is determined based on the aperture value of the aperture 14 and the zoom position of the zoom lens 12 at the present time.
Ten unit movements are calculated. Then high pass filter
The high frequency component amount (focal voltage) of the video signal extracted by 51 is A / D converted by the A / D converter 53 via the focus position selection analog gate 52, and the converted value V _x is the memory area x of the RAM 54. (Step 206).

Further, in step 207, the focus lens 10 is moved by the actuator 16 on the optical axis 90 by the unit movement amount calculated in step 205 to the camera body side (front side, close side). At this time, the high frequency component amount of the video signal obtained through the high pass filter 51 is
/ D conversion is performed, and the converted value V _y is written in the memory area y of the RAM 54 (step 208).

Next, at step 209 RAM 54 memory area x of, y written focus voltage V _x, compares the V _y is performed.
When it is determined that V _x <V _y , the process proceeds to step 220, the moving direction of the focus lens 10 is designated to the camera body side (front side), and the process proceeds to step 214.

When it is determined that V _x ≧ V _y , the moving direction of the focus lens 10 is designated to the infinity side on the subject side, and the focus lens 10 is moved to the infinity side by 2 unit movement amount (step 211, 212). At this time, the high frequency component amount of the video signal obtained through the high pass filter 51 is A / D converted by the A / D converter 53, and the converted value V _y ′ is written in the memory area y of the RAM 54 and updated. (Step 21
3).

Further, the focus lens 10 is moved by the unit movement amount in step 21.
1 or moved in the moving direction specified in step 220, the high frequency component amount of the video signal obtained through the high pass filter 51 at that time is A / D converted by the A / D converter 53, and the converted value V _z is written to memory area Z of RAM 54 (steps 214, 215).

Next, at step 216, the focus voltage values V _x , V _y , V _z (or V _x , V _y ′, V _z ) written in the memory areas x to z of the RAM 54.
By using Lagrange's interpolation polynomial, the maximum value of the function showing the focus curve and the coordinates showing the in-focus position where the maximum value is obtained are obtained.

Further, in step 217, as a result of the calculation in step 216, it is determined whether or not the maximum value exists. If the maximum value exists, the focus lens 10 is moved to the actuator at the coordinate position on the optical axis 90 where the maximum value exists. It is moved by 16 (step 221). When it is determined in step 217 that the maximum value does not exist, the focus voltage value V _z written in the memory area z of the RAM 54 is rewritten in the memory area x, and the focus lens 10 has already moved by the unit movement amount in step 211. Alternatively, it is moved in the direction specified in step 220 and then returns to step 213 (steps 218, 21).
9). After that, the series of processing in steps 213 to 219 is continued until the maximum value of the function indicating the focus amount curve is obtained.

Fine adjustment of the focusing of the focus lens 10 is performed by the above processing.

Next, FIG. 5 shows an example of a specific configuration of the focus position selection analog gate 52. In the figure, the focus position selection analog gate 52 includes first and second counters 520 and 521, third and fourth counters 525 and 526, and third and fourth counters 525.
And 526 and a clock generator 522, the first
And the second flip-flop (hereinafter referred to as F / F) circuit 523
And 527, and an AND gate 524 and an analog switch 528.

Next, the operation of the focus position selection analog gate 52 thus configured will be described with reference to FIGS.

Now, it is assumed that the video signal designated by the sound on the screen of the cathode ray tube 2a constituting the viewfinder as shown in FIG. 6 is to be taken out. It should be noted that 1H of the clock signal generated from the clock generator 522 (for example, 5H
In 25 scanning lines, the number of pulses per 63.5 μs) is the same as the H-direction grid on the viewfinder.

Next, the control circuit 50 divides the coordinates designated by the voice of the cameraman into the start and end in the H and V directions, respectively, and outputs them as data to the counters 520 and 521 forming the focus position selection analog gate 52 (sixth). See figure).

The counters 520 and 521 count the number of clock signals after the Hsync signal becomes active, and output a pulse to the CRT 2a when the start and end positions of the designated area on the screen are reached. This pulse is used as a control signal of the analog switch 528 in the H direction by the F / F circuit 523.

The counters 525 and 526 count the Hsync signal after the Vsync signal becomes active, and the Vsync signal is the same as in the H direction.
Generate a control signal for the analog switch 528 in the direction.

The control signal of the analog switch 528 in the H and V directions is input to the AND gate 524 to input the analog switch 5
Control 28.

In this way, the video signal of only the portion designated by the voice can be taken out.

In the above embodiment, an example in which the focus operation is performed in advance by the manual operation member 32 after designating the focus area on the screen of the CRT 2a that constitutes the viewfinder 2 has been described. The focusing operation (focusing operation by the first focusing means) may be performed by the next focusing means. That is, a focusing operation based on a stored value of a focusing position defined by a so-called shot box used when shooting a drama, and an automatic focus adjustment device such as a zone focus type automatic focus adjustment device. The focusing operation may be performed by the output signal of the above, and the same action and effect can be obtained by combining these with the second focusing means for finely adjusting the high spatial frequency component which is difficult to visually determine according to the present invention. It can be done.

Further, the activation of the second focusing means may be performed not only after the operation of the first focusing means is completed but also by an external manual operation as a trigger.

Further, a bandpass filter may be used instead of the highpass filter 51.

Further, in the above embodiment, the CR that constitutes the viewfinder
Although the focus area on the T screen is specified by voice input, the focus area is not limited to this. For example, the focus area can be specified by moving the cursor on the CRT screen by key operation. Alternatively, a touch sensor may be provided for each division on the CRT screen, and the focus area may be designated by touching the division to be designated with a finger.

Further, the designation may be made by a method of tracking the eye movement of the operator looking into the viewfinder.

Further, although a voice recognition unit dedicated to the cameraman is provided in the above embodiment, for example, two voice recognition units dedicated to the cameraman and the director are prepared and connected to the control circuit 50 respectively.

Then, prioritize the voice recognition section dedicated to the cameraman and the voice recognition section dedicated to the director in advance,
Make sure that the voice recognition unit dedicated to the director has the highest priority.

In such a case, on the screen shown in FIG. 4, it is assumed that the director intends to focus on the tree 105 and the cameraman intends to focus on the person 103.

At this time, the cameraman is "1" which is the division coordinate of the person 103.
Suppose that you chanted "8", while the director chanted "7" which is the division coordinate of the tree 105.

Then, as described above, the voice recognition unit dedicated to the director is prioritized, and in this case, the tree 105 can be focused.

Therefore, according to the present embodiment, for example, the focus man is unnecessary, and the intention of the director is directly expressed on the screen.

Therefore, it is possible to reduce the number of focus persons by one person, which is useful for labor saving, and the intention of the director is directly reflected on the screen.

Further, according to the present embodiment, the photographing optical system of the television camera can be focused on the subject even in the focal depth region of the spatial frequency component where visual judgment is difficult.

〔The invention's effect〕

As described above, according to the present invention, the focusing of the photographing optical system is adjusted by the manual focusing means for the subject in the area on the screen of the viewfinder designated by the focusing area designating means, and the manual focusing is performed. According to the present invention, fine adjustment of focusing of the focus lens is performed by the automatic focusing means that operates in response to a start signal generated based on the end of the focusing operation of the focusing means or an external manual operation. Viewfinder of TV camera or monitor The focus lens of the shooting optical system of the TV camera can be focused on the basis of instructions from the director watching the TV, etc., and even for high spatial frequency components that are difficult to judge visually. Fine adjustment of focusing of the focus lens can be performed.

[Brief description of drawings]

1 is a perspective view showing an appearance of a television camera to which the present invention is applied, FIG. 2 is a block diagram showing a configuration of an embodiment of a focus adjustment device for a television camera according to the present invention, FIG. 3A and FIG.
FIG. 3B is a flow chart showing the contents of the processing routine executed by the control circuit shown in FIG. 1, and FIG. 4 is an explanatory view showing an example of the viewfinder screen of the television camera.
FIG. 6 is a block diagram showing an example of a concrete configuration of the focus position selection analog gate shown in FIG. 1, and FIGS.
Timing chart showing the operating state of the focus position selection analog gate shown in Fig. 9, Fig. 9 is the viewfinder CRT
FIG. 10 is an explanatory view showing an example of a screen displayed in FIG. 10, FIG. 10 is a characteristic diagram showing a focus amount curve when the aperture value is used as a parameter, and FIG. 11 shows an example of the focus amount curve, showing the maximum value of the focus amount curve. Characteristic diagram for explaining the calculation contents when obtaining,
FIG. 12 is a characteristic diagram showing the characteristic of the depth of focus with respect to the aperture value with the resolution as a parameter. 2 ... Viewfinder, 2a ... CRT, 10 ... Focus lens, 14 ... Aperture, 16 ... Driving actuator,
20 …… D / A converter, 30, 31, 36, 53 …… A / D converter, 32…
… Operation member, 33 …… External start button, 50 …… Control circuit, 51…
… High-pass filter, 53 …… Focus position selection analog gate, 54 …… RAM, 60 …… Voice recognition section, 61 …… Analog interface, 62 …… Computation processor, 63 …… Registration memory, 64 …… System control section .

Claims (5)

(57) [Claims] 1. A photographing optical system including a focus lens for focusing on a subject, an image pickup means for converting a subject image formed by the photographing optical system into a video signal, and the video signal in a predetermined format. Signal processing means for performing conversion processing on the subject, a viewfinder for receiving a video signal from the signal processing means and displaying the subject on a monitor, and an area for focusing the photographing optical system using the screen displayed on the viewfinder. Focusing area designating means for designating a focus area, manual focusing means for focusing by moving the focus lens in the optical axis direction based on a manual operation of an operating member, and the video signal from the signal processing means. A high spatial frequency component is extracted from a video signal showing an image of a region designated by the focusing region designating means, and an integrated value of the extracted high spatial frequency component A focus adjustment method for a television camera, comprising: an automatic focusing unit that moves the focus lens in the optical axis direction so as to have a maximum value to perform focusing with higher focusing accuracy than the manual focusing unit. Fine adjustment for stopping the focusing by the automatic focusing means and setting the state in which the focusing by the manual focusing means is possible as a standard state, stopping the focusing by the manual focusing means and performing the focusing by the automatic focusing means A mode is provided, focusing is performed in the standard state, when focusing in the standard state is completed, focusing is performed in the fine adjustment mode, and when focusing in the fine adjustment mode is finished, the standard state is set. A method for adjusting the focus of a television camera, which is characterized in that it automatically returns. 2. The focus adjusting method for a television camera according to claim 1, wherein the automatic focusing means performs focusing when an external starting means is operated. 3. A photographing optical system including a focus lens for focusing on a subject, an image pickup means for converting the subject image formed by the photographing optical system into a video signal, and the video signal of a predetermined format. Signal processing means for performing conversion processing on the subject, a viewfinder for receiving a video signal from the signal processing means and displaying a subject image on a monitor, and focusing of a photographing optical system using a screen displayed on the viewfinder. Focusing area designating means for designating an area, and an image showing an image of an area on the screen of the designated viewfinder in the video signal output from the signal processing means in response to the output signal of the focusing area designating means. Focusing position determining means for extracting only the signal, and focusing by moving the focus lens in the optical axis direction based on manual operation of the operating member. A high-frequency spatial frequency component is extracted from the output signal from the manual focusing means and the focusing position determining means, and the focus lens is set to the optical axis so that the integrated value of the extracted high-frequency spatial frequency component becomes a maximum value. A state in which the automatic focusing means for moving the camera in the direction to perform focusing with higher focusing accuracy than the manual focusing means and the focusing by the automatic focusing means are stopped to enable the focusing by the manual focusing means. In the standard state, a fine adjustment mode for stopping the focusing by the manual focusing means and performing the focusing by the automatic focusing means is provided, and the focusing in the standard state is performed and the focusing in the standard state is performed. When the adjustment is completed, the focusing in the fine adjustment mode is performed, and when the adjustment in the fine adjustment mode is completed, the control unit is controlled to automatically return to the standard state. Focusing apparatus of a television camera, characterized in that it comprises a. 4. The high-pass filter for extracting a high-frequency spatial frequency component from an output signal from the focus-position determining means, and the high-frequency spatial frequency component extracted by the high-pass filter are integrated by the automatic focusing means. An integrating means for obtaining an integrated value and the focus lens a plurality of times at predetermined time intervals,
A first drive means for moving a predetermined amount of movement;
Calculating means for calculating the moving position of the focus lens at which the integrated value is maximized based on the integrated value obtained from the integrating means at each moving position by the driving means, and the moving position calculated by the calculating means. The focus adjusting device for a television camera according to claim (3), further comprising: a second driving unit that moves the focus lens. 5. The focus adjusting device for a television camera according to claim 3, wherein the control means performs focusing by the automatic focusing means when an external starting means is operated. .