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Description  |
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BACKGROUND OF THE INVENTION
A multiplicity of television cameras are used at the present time to
televise sporting events, such as football, basketball, golf and hockey
games, as well as races, and the like. Each camera is monitored by a
program editor, and the program editor determines the camera selection in
order that the game in progress may be televised from the best camera
angle and position as the action moves about the playing area.
Each cameraman pans his camera to follow the action, and he also zooms his
camera into the point of action when appropriate in order to reproduce the
action either on a close-up or long-shot basis, whichever is warranted at
any particular time.
It is the present practice for the cameraman to adjust the focus of his
camera manually as the camera is panned and whenever the zoom control is
activated. The focus control usually comprises a manually operated
mechanical, or electro-mechanical device mounted adjacent to the left of
the two panning handles of the television camera, and the presentday
television camera also usually includes a zoom control in the form of a
second mechanical or electronically activated device adjacent to the right
panning handle of the camera.
Then, as the cameraman pans his camera to follow the action on the playing
field, he turns the focus control handle in an attempt manually to
maintain the camera in focus during the panning operation. Also, when the
cameraman zooms in on the action, he must also adjust the focus control to
keep the camera in focus as closely as possible.
It is obvious that there are limits in the prior art to the ability of the
cameraman manually to keep his camera in focus at all times, especially
when the action is rapid and he is attempting to follow, for example, the
flight of a ball or puck. In accordance with the present invention, the
television cameras are all computer controlled so that each is
automatically maintained in focus regardless of how fast moving the action
may be, so that the cameraman need merely to pan his camera to follow the
action, and to zoom in on the action, without any necessity to manually
control the focus during any of these operations.
In broadcast sports television today, the prevailing practice is to place
the cameras perpendicular to the general path of action so as to minimize
focusing problems. However, this camera placement maximizes the necessary
panning action of the cameras and introduces panning problems as the
cameras attempt to follow rapid action. These problems include improper
framing, or losing the action from the camera frame, or blurring the
action due to panning at the wrong speed. One objective of the system of
the invention is to overcome to a large extent the foregoing panning
problems by permitting more favorable camera placements.
The system of the invention makes possible many exciting camera angles by
following a ball or puck, for example, during a ball game or a hockey
game, and for maintaining perfect focus at all times which is beyond the
capabilities of the prior art manually focused cameras. In brief, the
improved control system of the present invention serves to instantaneously
and automatically maintain each television camera of a plurality of
cameras used for televising a sporting event, and the like, in perfect
focus as the cameras are panned and zoomed to follow the game action, so
as to obviate any need for the cameraman to concern himself in any way
with the focusing of his television camera.
The system of the invention has many significant advantages over manual
focusing systems and existing automatic focusing systems which are based
on energy reflection, optical cybernetics and multiple camera
triangulation. These advantages include superior speed, greater accuracy,
higher resolution, greater flexibility, cost effectiveness and multiple
camera capability.
Speed, as referred to above, refers to the ability of a system to operate
quickly enough to maintain critical focus as cameras follow continuous
rapid action, and in the case of discontinuous activity, to have the
cameras already in focus as they pan to and/or zoom in on the new area of
activity.
An advantage of the computerized automatic multiple camera-focusing system
of the present invention lies in the ability of the operator, one who is
knowledgeable in the particular sport, to anticipate and/or to react to
rapid and capricious movements, and to effect the proper input to the
computer by the digitizing tablet, which then immediately focuses the
involved cameras. Such an operator can quickly manipulate the
"depth-of-field" in the direction of the activity so that both the desired
object and its eventual destination can be in focus rather than just one
or the other.
The prior art optical cybernetic focusing system is unsatisfactory in rapid
action sport situations because the system relies on error input in order
to initiate correctional procedures. Objects moving rapidly toward or away
from a camera will always be somewhat out of focus because of the lag time
involved in the cybernetic system. Also, the destination of the moving
objects will be out of focus as they come into frame. When cameras pan to
and/or zoom in on objects far from the original focus point, the objects
will be out of focus before the cybernetic correctional processes are
initiated properly to focus them.
The speed of the computerized automatic multiple camera focusing system of
the present invention is greater than prior art systems and camera
operators because the input to the computer eliminates the tendency to
wait for focusing errors to manifest. This is accomplished by the system
of the invention by anticipating and/or reacting to the true direction of
action and inputting that directionality as it is happening so as to
maintain a sharp focus on the proper object and its eventual destination
without any error signal correctional lag.
An automatic focusing control system based on energy reflection is suitable
for tracing rockets heading for space, but is unsuitable in conjunction
with sporting events. The accuracy of the prior art mechanical
multiple-camera triangulation system depends on the concerted skill of
three or more camera operators, all accurately framing the proper subject.
They are constrained by looking through their lenses into viewfinders. If
one or more of the operators loses the object, the entire system goes out
of focus.
The computerized automatic multiple camera focusing. system of the present
invention, using human intelligent inputs, is exceedingly accurate.
Wherever the action in reality is, or is about to be, the operator moves
the electronic pen on the tablet. Lenses are never accidentally set at
infinity, nor are they set to focus on irrelevant foregrounds leaving the
true objects of focus and their destinations blurred.
SUMMARY OF THE INVENTION
A computerized automatic multiple-camera focusing system which comprises a
computer-controlled lens-motor drive that receives input from a
human-operated digitizing tablet equipped with an electronic stylus for
tracing continuous action taking place on a playing field.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic representation of an elemental system illustrative of
the concepts of the present invention;
FIG. 2 shows an overlay which may be placed over the top of a digitizing
tablet included in the system of FIG. 1, and which is representative of
the playing area of the particular game being televised;
FIG. 3 is a block diagram of an automatic focusing control system
incorporating the principles and concepts of the invention; and
FIG. 4 shows a second embodiment of the system of the invention in which
the digitizing tablet is transparent and the playing area is viewed
through the tablet.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
As shown, for example, in FIG. 1 the system of the invention may include a
digitizing tablet 10. The digitizing tablet may be any commercially
available tablet, such as the "Tiger Tablet" presently being marketed by
Hitachi America, Ltd. of Torrance, Calif.
The digitizing tablet 10 is equipped with a stylus 12 which is intended to
moved manually across the playing surface presented by the top of the
tablet. As the stylus is moved across the plane surface, the tablet
generates digital signals representative of the ordinate and coordinate
positions of the stylus.
These digital signals are fed to a computer 14 which may be any
commercially available computer, such as, for example, the Sony SMC70,
which is presently being marketed by Sony Electronics Corporation of
Inglewood, Calif.
The computer 14 responds to the digital signals from the digitizing tablet
10 to produce focusing control digital signals for a multiplicity of
television cameras, such as a television camera 20. Television camera 20
is pivotally mounted on a tripod 22 which is equipped with a lens
designated 23 contained in a lens cover 25. The television camera also
includes a pair of angularly spaced handles, such as handle 24 by which
the cameraman may rotate the camera about the vertical axis of the tripod
for panning purposes. The camera 20 also includes a conventional zoom
control servomotor for its lens 23 which is contained within lens cover
25, and which is manually adjusted by a zoom control potentiometer (not
shown) mounted adjacent to the right-hand panning handle (not shown). The
zoom control potentiometer is connected to the servomotor by a cable 26.
The camera also includes a conventional focus control servomotor 34 for
its lens 23 which is normally mounted within lens cover 25, and which is
controlled by a focus control potentiometer 26 mounted adjacent to the
lefthand panning handle 24.
The cameraman follows the action with camera 20 by turning the camera about
the vertical axis of tripod 22 by the panning handles 24, so that the
camera may pan the action as it moves about the playing area. Also, the
cameraman may zoom in on the action by operating the zoom control
potentiometer. At all times, as the camera is panned and/or zoomed, the
cameraman must turn the focus control handle to maintain the camera in
focus, insofar as the prior art cameras are concerned. Camera 20, for
example, may be an Ikegami camera designated HK-257A, which are available
from Ikegami Electronics (U.S.A.) Inc., Maywood, N.J. Lens 20A may be a
Fujinon R44.times.13.5 ESM BCTV zoom lens available from Fujinon, Inc.,
Scarsdale, N.Y.
In accordance with the present invention, the digital focus signals from
computer 14 are converted to corresponding analog signals in a
digital-to-analog converter 30 which is connected to the computer. The
resulting analog signals from converter 30 are introduced to a servo drive
system 32 which, in turn, controls the existing camera lens focus control
servo motor 34, so that the focus of the camera lens may be controlled
automatically. The manual focus control potentiometer 26 provides a manual
focus control override, if so desired, when the cameraman actuates an
enable/disable switch 27 adjacent to switch focusing potentiometer 26.
The computer 14 is programmed to respond to the digital signals from tablet
10 and to calculate corresponding focus control signals for camera 20, as
determined by the actual location of camera 20 with respect to the playing
area.
During the progress of the sporting or other event, an observer watching
the event moves stylus 12 across the plane surface of digitizing tablet
10. Computer 14 responds to the digital signals generated by tablet 10 to
generate focus control digital signals in response thereto as determined
by the position of camera 20 with respect to the sporting event. The focus
control digital signals from the computer are converted into analog
signals by converter 30, and the servo drive system 32 responds to the
analog signals to drive servo motor 34 which, in turn, holds the camera in
focus as it is panned to follow the action on the field.
As shown in FIG. 2, an overlay 50 bearing inscriptions corresponding to the
playing field of the particular sporting event being televised is placed
over the plane surface of tablet 10. In the particular illustration of
FIG. 2, the sporting event is a football game. It is pointed out that
other overlays are provided for other sporting events. The overlay permits
the observer following the action on the playing area to move stylus 12
across the plane surface of tablet 10 to different positions on the
overlay 50, so that the action on the field may be followed by the stylus.
The cameraman operating camera 20 is also following the action with his
camera, and his camera is automatically focused by the positioning of the
stylus on the overlay.
In the block diagram of FIG. 3, computer 14 is shown as controlling a
plurality of television cameras designated 20A-20H which are positioned
around the playing area at pre-selected positions. The position of each of
the television cameras is related to a selected coordinate system, and the
individual positions are programmed into computer 14. Then, as the stylus
12 is moved across the overlay 50, the digital signals generated by tablet
10 are converted in the computer to different sets of focusing signals,
one set being used for each of the various cameras. The resulting digital
focusing signals may be transmitted separately to the various cameras, or,
as shown in FIG. 3, may be multiplexed in a multiplexer 52, and
transmitted over a single cable to the cameras.
In operating the system of FIG. 3, the cameraman for each of the cameras
20A-20H follows the action with his camera by appropriate panning and
zooming operations. At the same time, the observer follows the action with
stylus 12 on game overlay 50. The computer responds to the digital signals
from digitizing tablet 10 to provide focusing control signals for each of
the television cameras 20A-20H so that each camera is automatically
maintained in focus as it is panned and zoomed by its cameraman.
In the embbdiment of FIG. 4, the digitizing tablet 10 is replaced by a
transparent digitizing tablet 100 which may be a high resolution Scriptel
digitizing tablet having height and width dimensions, for example, of
24".times.36" and a resolution of the order of 864 million X/Y
coordinates. The operator observes the action on the sports field through
the transparent digitizing tablet 100, and follows the action on a
three-dimensional representation, which in this case is in the form of a
trapezoid 102 by the stylus 12. The stylus is capable, for example, of
feeding 200 coordinate pairs per second through a microprocessor 104 to
computer 14. Microprocessor 104 may be a central processing unit of the
type designated 8088. The computer 14 processes the data as in the
previous embodiment, and transmits corresponding digital signals by hard
wire or multiplexed over existing triax cable to the cameras at, for
example, a data rate of 200 bytes per second per camera. As described
above, the digital signals are converted at each camera into analog servo
signals by appropriate analog converters.
A numeric key pad 106 is included in the system for actuating
pre-programmable focus locations.
With the transparent tablet 100, it is possible for the operator to look
directly at the live action and to trace the action directly with stylus
12 on the digitizer which, as shown in FIG. 4, is vertically positioned in
front of the operator. Placing the stylus 12 directly on what the operator
actually sees focuses all the cameras linked to the computer 14 exactly on
that spot. In the embodiment of FIG. 4, it is not necessary for the
operator to look up-and down between the action and the tablet as is the
case in the embodiment of FIG. 1.
The computer may respond to voice-activated commands from the operator
which causes it to activate the lens focusing controls in much the same
way as moving the stylus or pressing the key pad buttons. For example, in
observing a baseball game, the operator may say "centerfield" and the
computer would then cause the lenses of the system to focus on the normal
location of the centerfielder.
In addition, each independent camera operator may have the option of
manually switching to a separate voice-activated computer. Thus, if the
centerfielder, for example, is running back toward the wall to catch a fly
ball, the command "farther" would focus the lens of that particular camera
in increments of a specified number of feet.
The invention provides, therefore, a computerized multi-television
automatic focusing control system which serves to maintain each of a
multiplicity of television cameras automatically and instantaneously in
focus, as the cameras are moved to follow the action on the playing area.
As mentioned above, the use of the automatic system of the invention, in
addition to maintaining perfect focus for all normal shots of the action,
also enables exciting camera angles to be used to follow, for example, a
moving ball or puck, while maintaining the object in focus at all times.
It will be appreciated that while particular embodiments of the invention
have been shown and described, modifications may be made. It is intended
in the claims to cover all modifications which come within the true spirit
and scope of the invention.
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