JPH07121082B2 - Autofocus device for television cameras - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an autofocus device for a television camera, and more particularly, when a television cameraman gazes at an object projected on a viewfinder for a monitor of the television camera, the television cameraman automatically The present invention relates to an autofocus device for a television camera in which a subject gazed at is in the best focus.

[Conventional technology]

For example, international athletics games and large rugby games may be broadcast on television. In such a case, several television (hereinafter referred to as TV) cameras are installed, but some of them are fixed at a relatively high place in the stadium and give a bird's eye view of the athletes who are the subjects. I sometimes try to show it.

This situation will be described with reference to FIG.

As shown, a player 109 is playing on the ground of the stadium 111.

On the other hand, a TV camera 113 is installed by a tripod 114 on a hill 112 that is relatively high in the stadium, and a cameraman 115 operates the TV camera to capture the player 109 with the TV camera 113. become.

In this case, since the depression angle θ when looking down at the player 109 from the TV camera 113 and the height H from the player 109 to the TV camera 113 can be measured by an appropriate means, the distance between the player 109 and the TV camera 113 can be calculated. If there is L, there is a relation of the following equation between them.

That is, in order for the television camera 113 to focus on the player 109, it becomes possible to focus if the distance L shown by the above equation is known.
-151830 "(apparatus and method for improved autofocus camera)
The suggestion was made.

[Problems to be solved]

However, as mentioned above, when an athletics athlete is running on the track, it is naturally difficult to focus because the athlete's movements are intense, and it seems that the athlete is particularly up-closed. In that case, it was difficult to maintain the best focus, so I tried to show a player with a lot of movement while pulling the camera vividly (that is, in a wide-angle state).

In addition, when relaying a game with particularly intense movements such as American football, the cameraman of the TV camera fixed on the hill can freely control the focus demand and zoom demand of the TV camera, and in extreme cases, the cameraman can view. Without observing the viewfinder, he used a skilled technique to operate a TV camera and take an up-screen with focus and zoom demand operations.

Therefore, a TV cameraman who relays a sport with a lot of movement needs a particularly skilled technique.

[Means and Actions for Solving Problems]

In order to solve the above problems, the present invention captures an optical path that reciprocates between the retina of the fundus and a point on the viewfinder when gazing at a point on the viewfinder provided in the television camera. A line-of-sight direction detection unit, a tilt angle sensor that detects an angle of the television camera directed to the subject in the tilt angle direction,
Based on the output from this tilt angle sensor, the coarse focus adjustment unit that roughly adjusts the focus of the subject, the wobbling method detection unit that finely vibrates the lens to adjust the focus by the wobbling method, and at least the detection result of the line-of-sight direction detection unit. A control unit that determines the line-of-sight direction coordinates on the viewfinder, and a focus position determination unit that extracts the video signal of only the part where the line of sight is facing based on the coordinate data output on the viewfinder from this control unit. A focus lens drive unit for the photographing lens that drives the photographing lens to the best focus on the subject in the line-of-sight direction based on the output result of the focus position determination unit, and any of the subject images in the coarse focus adjustment state on the viewfinder It is detected whether the line of sight is facing to, and the image is taken only based on the video signal of the part where this line of sight is facing. It drives the focus lens of the lens, in which so as to focus the direction of the object facing the line of sight.

〔Example〕

An autofocus device for a television camera according to the present invention will be described below with reference to an embodiment shown in the drawings.

For details of the "gaze direction detecting device" used in the present invention, refer to the patent application "gaze direction detecting device" previously filed by the applicant on February 26, 1987.

FIG. 1 is a block diagram showing the overall configuration of an autofocus device for a television camera according to the present invention.

As shown in the figure, a television camera (hereinafter referred to as a TV camera) includes a camera body 10 and a zoom lens 20 which is a photographing lens.
And viewfinder 30 etc.

The line-of-sight direction detecting device 100 is arranged on the front side of the cathode ray tube 6 provided in the viewfinder 30 which is a television monitor. Then, this line-of-sight direction detection device 10
The first half mirror 102 is arranged so as to be on the optical axis when the screen of the cathode ray tube 6 is observed from the eyepiece 101 of 0 by the eyeball 108 of the television cameraman.

A second half mirror 103 is arranged below the first half mirror 102, and the second half mirror 103 is provided.
An infrared LED 105 having a large number of light emitting diodes (hereinafter, referred to as LEDs) that emit infrared rays invisible to human eyes is disposed on the left side of the infrared LED 105. This LE
The D105 is driven by the LED array drive circuit 104, and its control (sequential lighting) is performed by the controller 21 described below.

Further, below the second half mirror 103, a light receiving element 106 composed of a two-dimensional photosensor or the like is arranged, and this light receiving element 106 is connected to a photoelectric signal amplification circuit 107 so that a weak signal is generated. Is amplified.

In this line-of-sight direction detection device 100, an infrared LED 105, which is a light-emitting body, is arranged at a point optically conjugate with the observation surface of the cathode ray tube 6, and the line of sight of the eyeball 108 of the TV cameraman is on any one of the cathode ray tubes 6. When pointing to a point, L corresponding to the address of the LED on the infrared LED 105 corresponding to this point
Only the ED strongly reflects light, and the reflection is captured by the light receiving element 106, and the position is calculated by the control unit to determine the position of the line of sight.

A detailed description of this "line-of-sight direction detection device" is given in the above patent application, so please refer to it. Further, this patent application discloses three types of gaze direction detecting devices (FIG. 1, FIG. 2, and FIG. 5 in the previous patent application), but any of these three types can be used. It can be applied to the present invention.

The first lens group 11a forming the focus system lens (hereinafter referred to as the zoom lens 20) of the television camera is directed to the player 109 who is the subject. This first lens group 1
The second lens group 11b and the third lens group 11c are provided on the rear side of 1a.
Are sequentially arranged, and further known wobbling (WOBBLING)
A fourth lens 11d that is vibrated finely by the method is provided, and the fifth lens group 1 is provided behind the lens 11d.
1e is provided.

Then, the subject image obtained by the zoom lens 20 is photoelectrically converted by the image pickup device 1 such as a CCD constituting the image processing unit of the television camera and input to the process amplifier 3 via the preamplifier 2. The image pickup device 1 and the process amplifier 3 are supplied with the periodic pulse generated from the synchronizing signal generator 4.

An image (video) signal obtained from the process amplifier 3 is input to an image drive circuit 5 which constitutes a viewfinder 30, and an image is projected on the screen of the cathode ray tube 6.

On the other hand, a tripod 17 is attached to the lower side of the television camera body 10, and the camera body 10 is configured to be freely movable in the depression direction by the operation of the cameraman.

Further, a tilt angle sensor 16 for detecting a tilt angle is provided on the lower side of the zoom lens 20 of the TV camera,
This sensor 16 is connected to the first input terminal of an analog switch 18, and the tilt angle is sent to the controller 21 as a signal via this analog switch 18, and the tilt angle is calculated as a specific number in this controller 21. It is supposed to be done.

The second input end of the analog switch 18 is connected to the output end of the photoelectric signal amplifier 107 that constitutes the line-of-sight direction detection device 100, and the output end of the analog switch 18 is an analog / digital (hereinafter referred to as A / D The controller 21 is connected via a converter 19 to a controller 21 including a one-chip microcomputer that controls the entire autofocus device.

The first output end of the controller 21 is connected to the third input end of the analog switch 18 and receives either the input signal from the photoelectric signal amplifier 107 or the input signal from the tilt angle sensor 16. The second output terminal is controlled to be selected, and is connected to a vibrator driving circuit 15 that drives a vibrator 14 including a voice coil by the wobbling method.

The fourth output end of the controller 21 is connected to the input end of the LED array drive circuit 104, and the infrared LED 10
It is designed to control whether any one of the LEDs composing 5 lights up.

The V _start signal is output from the fifth output end of the controller 21, the V _END signal is output from the sixth output end, and the
H _start signal is output from the output end of
The H _END signal is output, and all of these signals are supplied to the focus position selection analog gate 22 which is designed to extract the video signal of only the portion where the line of sight of the TV cameraman is facing. It should be noted that these V _start signals and the like are signals used to determine the gazed area on the screen on the cathode ray tube 6.

Video drive circuit 5 constituting the viewfinder 30
The second output terminal of is connected to the input terminal of the sync separation circuit 24,
A vertical sync (V _sync ) signal is output from the first output terminal of the circuit 24 and supplied to the analog gate 22, and a horizontal sync (H _sync ) signal is also supplied from the second output terminal. There is. Further, the video signal is output from the third output terminal of the sync separation circuit 24, and is supplied to a bandpass filter (hereinafter referred to as BPF) 25 that extracts only harmonic components. The focus position selection is input to the analog gate 22.

The first output end of the focus position selection analog gate 22 is connected to the first input end of a known high speed A / D converter 26 for video signals, and the second output end of the analog gate 22 is a timing signal. Is supplied to the high speed A / D converter 26 and is connected to the second input terminal of the controller 21. The output terminal of the high-speed A / D converter 26 is connected to the third input terminal of the controller 21 and sends only the video signal in the line-of-sight direction determined by the analog gate 22 to the controller 21.

The output end of the controller 21 is connected to a motor drive circuit 13 that rotationally drives a motor 12 that drives the first lens group 11a of the zoom lens 20 back and forth.

Next, the operation of the autofocus device of the TV camera configured as described above will be described based on the flowchart shown in FIG.

First, suppose a TV cameraman points his TV camera at player 109 in the stadium. Then, the tilt angle sensor 16
The output obtained by is sent to the controller 21 via the analog switch 18 and the A / D converter 19, and the controller 21 calculates the distance L between the player 109 and the TV camera. Then, a drive signal is sent from the motor drive circuit 13 to the motor 12 based on the calculation result, and the first lens group 11 is driven.
a moves to perform coarse focus adjustment.

Then, the subject image of the player 109 in the rough adjustment state is projected on the screen of the cathode ray tube 6 via the zoom lens 20, the image processing unit, and the like. The eyeball 108 of the television cameraman observes the subject image projected on the screen of the cathode ray tube 6.

At this time, if the eyeball 108 of the television cameraman gazes at any of the subject images, the gaze of the CRT 6
The upper position is detected by the line-of-sight direction detection device 100, sent to the analog switch 18, further converted into digital data by the A / D converter 19, and supplied to the controller 21.
Then, the controller 21 calculates and determines the coordinates on the cathode ray tube of the subject image (that is, the portion to be focused) which the TV cameraman is gazing at.

Then, since a signal is sent from the second output end of the controller 21, the vibrator 14 vibrates and vibrates the fourth lens 11d at, for example, several tens Hz. Then, the fourth lens 11d slightly vibrates by the well-known wobbling method, and the subject image is sent to the video drive circuit 5.

On the other hand, since the video signal which is the output signal of the video drive circuit 5 is also sent to the sync separation circuit 24, V
_{The sync} signal and the H _sync signal are separated, and the video signal is further supplied to the BPF 25, where only the harmonic components are extracted.

Then, in the focus position selection analog gate 22, the video signal of only the portion in which the line of sight detected by the line-of-sight direction detection device 100 is extracted is extracted, and the high-speed A / D converter 2
Sent to 6.

From the output end of this high-speed A / D converter 26 to the controller 21
A signal is sent to.

Then, in the controller 21, a signal is sent from the third output end to drive the motor drive circuit 13 to drive the motor 12
Is rotationally driven to move the first lens group 11a back and forth to set the best focus position.

An example of the focus position selection analog gate 22 shown in FIG. 3 can be considered.

The focus position analog gate 22 shown in FIG.
And second counters 31 and 32 and third and fourth counters 36
37 and a clock generator 33, and further includes first and second flip-flop (hereinafter referred to as F / F) circuits 34 and 38.
And an AND gate 35 and an analog switch 39.

Next, the operation of the focus position selection analog gate 22 thus configured will be described with reference to FIGS.

Now, assume that it is desired to take out the video signal of only the shaded portion on the screen of the cathode ray tube 6 which constitutes the viewfinder as shown in FIG. 4, and the line of sight of the television cameraman is directed to the shaded portion.

The number of pulses per 1H (for example, 63.5 μs for 525 scanning lines) of the clock signal generated from the clock generator 33 is the same as the resolution in the H direction of the visual axis detection device 100.

Next, the controller 21 divides the coordinates where the cameraman's line of sight is directed (hit) into the start and end in each of the H and V directions, and selects the focus position analog gate
It is output as data to the counters 31 and 32 constituting 22 (see FIG. 4).

The counters 31 and 32 count the number of clock signals after the H _sync signal becomes active and output a pulse when the start and end positions are reached. This pulse
The analog switch control signal in the H direction is output by the F / F circuit 34.

Counters 36 and 37 are high after the V _sync signal becomes active.
_{The sync} signal is counted and an analog switch control signal in the V direction is generated as in the case of the H direction.

The H and V analog switch control signals are input to the AND gate 35 to control the analog switch 39.

In this way, it is possible to take out the video signal of only the part where the line of sight is hit.

〔effect〕

According to the present invention, only the subject image whose line of sight on the viewfinder is focused can be focused. Therefore, even if the subject moves fast, the TV cameraman can use the viewfinder for the focus control. You can get the best focus just by staring at, and you can operate the TV camera focusing on the zoom demand.

Therefore, even when a fast-moving subject image is overlooked and captured by a television camera, it is possible to create an image with the best focus even if the television cameraman is not very skilled as in the past.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing an autofocus device for a television camera of the present invention, FIG. 2 is a flow chart showing the operation of the autofocus device, and FIG.
An electric circuit diagram showing an example of a focus position selection analog gate shown in the drawings, FIGS. 4 to 6 are diagrams for explaining the operation of FIG.
FIG. 7 is a conceptual diagram when a fast-moving subject is overlooked and moved by a TV camera. 10 ... Camera body, 11a ... 1st lens group of lens system, 11d ... 4th lens group of lens system, 12 ... Motor, 14 ... Transducer, 16 ... Tilt angle sensor, 21 ... ... Controller, 22 ... Focus position selection analog gate, 24 ...
… Synchronous separation circuit, 25 …… Band pass filter (BP
F), 30 ... Viewfinder, 100 ... Gaze direction detector.

Claims (1)

[Claims] 1. A tilt angle sensor for detecting a tilt angle of a television camera, and angle information from the tilt angle sensor and height information between the subject and the television camera are used to obtain distance information between the subject and focus. A coarse focus adjustment unit for performing a coarse adjustment, and invisible light is incident from the viewfinder side toward the fundus of the observer who observes the viewfinder, and the reflection direction is changed by the observer's fundus gazing at an arbitrary position of the viewfinder. Invisible light emitting means defined, a line-of-sight direction detecting section for detecting the line-of-sight direction of the observer by detecting the reflection direction, and a wobbling method detecting means for finely vibrating the imaging system lens to detect the focus position by the wobbling method. And a calculation means for calculating a signal detected by the line-of-sight direction detection section, and a calculation result of the calculation means And a video image that changes by the wobbling method in a partial area of the subject image corresponding to the line-of-sight direction based on the coordinate data output on the viewfinder from the control unit. A focus position determination unit that determines the focus position based on the signal, and a focus system lens drive unit that drives the focus system lens to the best focus on the subject in the line-of-sight direction based on the output result of the focus position determination unit. After the coarse focus adjustment by the coarse focus adjustment section, the direction of the line of sight of the observer who gazes at an arbitrary position of the coarse focus adjustment state of the subject image on the viewfinder is detected, and the subject image corresponding to this direction of sight line is detected. The first focus system lens is driven based on the change of only the video signal by the wobbling method in a partial area of the It was to focus in the direction of the object facing the autofocus device of a television camera, characterized in.