Electric lamp and discharge devices: systems – Discharge device and/or rectifier in the supply circuit – Flashers
Reexamination Certificate
2003-03-20
2004-02-17
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Discharge device and/or rectifier in the supply circuit
Flashers
C315S24100S, C315S24100S, C362S321000, C340S870260, C340S870030
Reexamination Certificate
active
06693392
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to theatre lighting, and more particularly to a method and apparatus for generating a flash or series of flashes from a multiparameter light.
2. Description of Related Art
Theatre lighting devices are useful for many dramatic and entertainment purposes such as, for example, Broadway shows, television programs, rock concerts, restaurants, nightclubs, theme parks, the architectural lighting of restaurants and buildings, and other events. A multiparameter light is a theatre lighting device that includes a light source and one or more effects known as “parameters” that are controllable typically from a remotely located console, which is also referred to as a central controller or central control system. For example, U.S. Pat. No. 4,392,187 issued Jul. 5, 1983 to Bornhorst and entitled “Computer controlled lighting system having automatically variable position, color, intensity and beam divergence” describes multiparameter lights and a console. Multiparameter lights typically offer several variable parameters such as strobe, pan, tilt, color, pattern, iris and focus. See, for example, the High End Systems Product Line 2000 Catalog, which is available from High End Systems Inc. of Austin, Tex. The variable parameters typically are varied by optical and mechanical systems driven by microprocessor-controlled motors located inside the housing of the multiparameter light.
A stroboscopic effect is a number of high-intensity short-duration light pulses, which are commonly known as flashes. In conventional multiparameter lights, the strobe parameter is a stroboscopic effect realized with set of algorithms optimized to create a standard best quality stroboscopic effect using the mechanical shutter. The algorithms are stored in a memory of the multiparameter light and are evoked by control values from the remote console over a strobe or shutter control channel. However, other stroboscopic effects may be realized with different algorithms that do not necessarily create the standard stroboscopic effect. For instance, a random strobe with varying dark periods is another type of stroboscopic effect available over the strobe control channel. Other stroboscopic effects may also be available to be controlled over the strobe control channel, such as, for example, slow ramp up and fast ramp down strobes. These different stroboscopic effects typically are all controllable from the strobe control channel and make available more variants for the programmer of the lights.
Multiparameter lights typically use high intensity light sources such as metal halide lamps. A metal halide lamp typically requires a high voltage ignition system to “strike” the lamp into operation. The high voltage ignition system provides the high voltage required by the lamp to carry an electric current between the electrodes. Once current flow is established between the electrodes of the lamp, an operating supply voltage that is typically much lower than the striking voltage is employed to continuously operate the lamp.
If a lamp is shut off, the procedure of applying the striking voltage to the lamp to re-ignite the lamp must be repeated. If one desires to re-ignite a lamp that is warm from operating, the striking voltage needed is higher than the striking voltage needed to re-ignite a cold lamp. This is because as the lamp heats up during operation, the impedance between the electrodes rises. As the lamp cools down, the required striking voltage is reduced.
Because metal halide lamps require high voltage ignition systems and the voltage requirement for the ignition increased with lamp temperature, they cannot be switched off and on rapidly and continuously without considerable expense. Hence, multiparameter lights typically implement the stroboscope parameter by using mechanical shutters.
A mechanical shutter works by controllably blocking and unblocking the light beam from the lamp within the multiparameter light. The mechanical shutter may be formed of a metal such as aluminum, mirrored glass, or steel, and may be driven by a motor or an actuator such as a solenoid. When the mechanical shutter is placed by the motor to block the light beam, very little light exits the multiparameter light. When the mechanical shutter is placed to avoid blocking the light beam, i.e. when it is open, the path of the light through the shutter is clear and the full intensity of the light beam exits the multiparameter light.
More recently, alternatives to mechanical shutters have become available. Generally, a shutter may be any suitable means to block and not block (i.e. open) the light from the light beam created by the lamp, including electronic shutters that become more reflective and less reflective such as some LCDs and that redirect light such as DMDs and some LCDs.
While mechanical shutters are effective for a variety of stroboscopic effects, their usefulness is limited because the strobe contrast declines with an increasing strobe rate. Mechanical shutters are most often driven by motors that are controlled by a microprocessor-based control system located in the multiparameter light housing. The speed of the mechanical shutters is limited by the weight of the shutter itself and the capability of the motor driving the shutter. Mechanical shutters operate reasonably well and provide reasonable strobe contrast at low to moderate strobe rates such as, for example, one flash per second. However, the strobe contrast is reduced at higher strobe rates such as, for example, about ten flashes per second. Reduction in the strobe contrast occurs when the shutter cannot move fast enough to effectively block and unblock the light beam. At ten flashes per second, a mechanical shutter typically provides a poor contrast between the light duration and the dark duration. At greater shutter speeds, the contrast suffers so greatly that the stroboscopic effect produced by the multiparameter light is ineffective.
Illustrative shutter systems in common use are shown in
FIGS. 1-7
.
FIGS. 1-4
illustrate the mechanical action of one kind of shutter system commonly used for the stroboscope in the multiparameter light. Shown is a motor
2
, a motor shaft
4
, a wedge shaped shutter
6
, and a light beam
9
as illustrated by a circular dotted line. Also shown is an aperture
8
through the shutter
6
, for passing the light from the light beam unobstructed. In
FIG. 1
, the shutter
6
is in a light sustaining position, having placed the aperture
8
in coincidence with the light beam
9
as it moves at maximum velocity from top to bottom as shown by the long curved arrow. Next as shown in
FIG. 2
, the shutter
6
is in one darkness sustaining position, having moved the aperture
8
away from the light beam
9
while in the process of reversing direction. Next as shown in
FIG. 3
, the shutter
6
is in a light sustaining position, having placed the aperture
8
in coincidence with the light beam
9
as it moves at maximum velocity from bottom to top as shown by the long curved arrow. Next as shown in
FIG. 4
, the shutter
6
is in another darkness sustaining position, having moved the aperture
8
away from the light beam
9
while in the process of reversing direction. Next, the shutter
6
returns to a light sustaining position identical to the position shown in FIG.
1
.
FIG. 6
illustrates another type of shutter system. Shown is a motor
12
, a motor shaft
14
, a shutter
16
, and a light beam
19
as illustrated by the dotted circle. A large curve arrow indicates the direction of movement of the shutter
16
.
FIG. 7
illustrates another type of shutter system using two motors
22
and
32
and respective shutters
26
and
36
which are attached to motor shafts
24
and
34
. Large curved arrows indicate the direction of movement of the shutters
26
and
36
relative to a light beam
29
, which is illustrated by a dotted circle.
Electronic stroboscopic effects have been achieved using Xenon lamps in high power lighting devices other than multiparameter lights; see, e.g.
Altera Law Group LLC
Tran Thuy Vinh
Wong Don
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