Electricity: motive power systems – Positional servo systems – Program- or pattern-controlled systems
Reexamination Certificate
2001-06-22
2003-08-19
Dang, Khanh (Department: 2837)
Electricity: motive power systems
Positional servo systems
Program- or pattern-controlled systems
C318S572000, C318S573000, C352S053000
Reexamination Certificate
active
06608461
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the fields of motion picture and video production, and more particularly to apparatus and methods for motorizing and remotely controlling, using a digitally controlled microprocessor, existing manually operated geared heads for positioning motion picture and electronic medium (such as video) cameras.
Prior art geared heads for positioning motion picture and electronic medium cameras are usually operated manually. When the cameraman needs to move the camera right to left (known in the art as “panning” the camera) or up and down (known in the art as “tilting” the camera), the operator will rotate two hand wheels, each controlling an axis. For example, if the cameraman needs to make a 180 degree pan, he has to physically travel 180 degrees behind the camera in an arc with the camera to view the shot through the viewing system.
Referring now to
FIG. 1
, there is shown therein a typical prior art geared head system
11
. The illustrated geared head system
11
is sold under the trademark ARRIHEAD
2
, available from Arri, Inc. However, it is merely representative, and any similar type of geared head assembly could alternatively be referenced. The geared head system
11
includes a camera platform
13
, which is capable of adjustment in at least two axes, namely pan and tilt. A tilt handwheel
15
and a pan handwheel
17
are provided for use by the camera operator when it is desired to pan and/or tilt the camera (not shown) mounted on the platform
13
. The camera platform
13
is disposed on a gearhead housing
19
, within which reside a plurality of interengaged gears for selectively driving the camera platform, and thus the camera mounted thereon, through a predetermined range of motion in the pan and tilt axes. The gearhead housing
19
is supported by a plurality of legs
21
.
Thus, in operation, the camera operator is stationed behind the gearhead housing
19
, in position to actuate the two hand wheels
15
and
17
, and to view the scene through the viewfinder of the camera (not shown). To pan or tilt the camera, the hand wheels
15
and
17
are selectively rotated. Since the hand wheels
15
and
17
are drivingly connected to the interengaged gears via a manual tilt gear drive interface and a manual pan gear drive interface, respectively, rotation of the hand wheels
15
and
17
functions to drive the gears within the gearhead housing
19
, which in turn are drivingly engaged with the camera platform
13
. In other words, the hand wheels
15
and
17
are mechanically linked to the platform
13
so that a ratio of turns will be converted into movement, through the gearhead, in the tilt axis and the pan axis, respectively. In some embodiments (not shown), a third hand wheel or motor is provided which rotates the camera on a roll axis. There is no ability to provide predetermined fixed stops in pan, and in tilt, only the end of the permitted travel arc provides a hard stop. No intermediate stops may be selected.
Most existing geared heads have three mechanical gear ratios which enable the camera operator to choose the rate at which he would like to move the photographic device. Unfortunately, this limited selection of travel speeds can be very restrictive during a shoot.
With a conventional geared head, it is very difficult to move the camera rapidly and stop on a precise mark. Generally, since the operator cannot see beyond the viewing system when the final mark will be approaching, it is possible to either go beyond the final mark or to fail to reach the final mark. Geared heads for motion picture and electronic medium cameras were designed to assist the camera operator's ability to pan or tilt the camera from point A to point B with a greater degree of accuracy than was previously possible, in order to accommodate the ever more complex shots required in an increasingly sophisticated and demanding industry, but their present limitations continue to frustrate both camera operators and directors.
Presently available geared heads have virtually infinite panning ability, but are generally restricted to +/− approximately 30 degrees in tilt. It is possible, therefore, for the operator to reach a hard mechanical stop on the tilt axis during photography, which is unacceptable in most cases.
Additionally, because present motion picture geared heads are operated manually, it is possible to move the camera the same way multiple times, but never to replicate a previous camera move exactly.
Still another problem with existing geared head assemblies is the necessity for the camera operator to be positioned directly behind the assembly. Often, the camera must be placed in a relatively hazardous orientation in order to obtain an acceptable shot, and this entails danger and inconvenience to the operator. Although remote controlled cameras are presently available for such occasions, they are generally very expensive and relatively complex, and are not adaptable to typical geared head assemblies, thereby entailing a time consuming and complex “change-out” operation, or a separate camera assembly for those unique shots.
Various prior art systems have been developed for providing remotely controlled camera systems, particularly for ensuring repeatable shots and for permitting hazardous shoots without placing a camera operator in harm's way. For example, U.S. Pat. No. 4,673,268 discloses a remote camera operation system comprising pan and tilt tables which are each actuatable by respective stepper motors. These tables may be computer controlled for repeatable shot sequences. However, this system is not adaptable for use with existing gear heads.
U.S. Pat. No. 4,720,805 discloses a computer-controlled camera system for controlling pan and tilt motors remotely using a digitizing tablet. However, again, this system is not adaptable for use with existing gear heads.
U.S. Pat. No. 4,847,543 discloses a remote-controlled camera system which uses control handles similar to those used in certain manual systems to actuate pressure transducers, which convert the movements of the handles initiated by the camera operator to voltage signals for actuating pan and tilt motors at the camera. The purpose of this arrangement is to facilitate repeatability of camera operation. This is not a remote system, but rather requires the operator to be located at the camera location.
U.S. Pat. No. 5,220,848 discloses a remote camera operation system wherein handwheels are used to operate a prior art cine head, which has a video monitor instead of a camera mounted thereon. Sensors transmit signals to a central control unit, based upon movements initiated by the camera operator on the handwheels, thereby actuating step or stepless actuator head motors. This system is disadvantageous, however, in that it is a complex customized approach not readily adaptable for quick change-out and use with existing gear heads.
Therefore, it would be highly desirable to have a geared head assembly which is directly adaptable to existing geared heads, is simple and quick to change out, affords a substantially greater number of mechanical gear ratios to select from, in order to provide the camera operator with an increased range of pan and tilt speeds, is programmable to provide selectable soft stops in both the pan and tilt axes, and is capable of recording a complex move so that it can be repeated precisely as many times as desired.
SUMMARY OF THE INVENTION
The present invention solves the aforementioned problems by providing a two-axis or three-axis digitally controlled microprocessor for remotely controlling an existing manually operated geared head. Because of the digital technology, the camera operator has full precise control of the geared head from a remote distance, as if he or she were physically behind the geared head personally.
Additionally, by utilizing the inventive system's electronics, the operator has, in one preferred embodiment, ten gear ratios instead of the three gear ratios that typically exist in the prior art manual geared head. Also,
Dang Khanh
Stout Donald E.
Stout, Uxa Buyan & Mullins, LLP
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