Electrical transmission or interconnection systems – Plural load circuit systems – Selectively connected or controlled load circuits
Reexamination Certificate
2001-02-23
2004-11-09
Sircus, Brian (Department: 2836)
Electrical transmission or interconnection systems
Plural load circuit systems
Selectively connected or controlled load circuits
C315S324000, C700S011000
Reexamination Certificate
active
06815842
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a control circuit for driving and activating a plurality of electrical loads, especially electroluminescent loads such as electroluminescent fibers. More particularly, the present invention relates to a control circuit for sequentially driving such loads, one at a time (or one subset at a time), using the same power supply.
BACKGROUND OF THE INVENTION
Lighting controllers (e.g., lighting consoles or boards) are commonly found in theatrical, architectural, and entertainment venues. These controllers are operated by an individual and/or a computer system to activate and control relays, switches, dimmers, illuminators, and other control devices that are integrated within a lighting system. Those control devices are in turn connected to lighting devices (and possibly other devices such as mirrors, gobo wheels, and smoke machines) to operate or enable the lighting devices in a desired manner. In most lighting systems, controllers activate and interface with control devices using the Digital Multiplex (DMX) protocol. The DMX (or DMX-512) protocol is a digital control signal standard published by the United States Institute for Theatre Technology (USITT) and is used extensively within the lighting industry (a corresponding Analog Mulitplex, AMX or AMX-192, protocol also exists). A DMX signal can be used to control timed events, color changes, scene changes, and numerous other effects.
The current DMX control standard (established in 1986 and revised in 1990) provides up to 512 control channels per data link. Each device needs a certain number of DMX channels for proper operation. Some control devices require only one or two channels, while others may use 20 or more channels with separate channels controlling different effects such as activation, dimming, color, strobing, tilting, and rotation. Each control device in a lighting system is assigned a DMX start channel or address number (if a device uses several channels, those channels are addressed sequentially beginning at the start address). DMX channel assignment is typically achieved by setting a DIP (dual in-line package) switch on each control device. Once channels have been assigned, the devices are typically connected in a serial or daisy-chain configuration, in which the controller connects to an input of a first control device, an output of the first control device connects to an input of a second control device, and so on.
A DMX control signal provides data in an asynchronous serial format at 250 kbps via the industry standard RS-485 interface (also known as EIA-485). A typical DMX data packet includes a reset condition, followed by a start code and up to 512 bytes of control data, with one data byte for each channel. The start code is usually a “0” byte, however, a unique start code can also be used to indicate to a receiving device that a data packet containing proprietary information is being sent. Each channel byte in a packet provides information for controlling the corresponding device or device feature. Although the DMX standard was originally designed to carry dimmer information (i.e., information directly affecting the proportional output from a stage lighting dimmer), DMX control data has since evolved to carry information for moving lights, color changers, and a variety of other devices used within entertainment and architectural lighting industries. Typically, by programming or sliding a potentiometer on a control console, a control output can be varied from 0-100% (with 8-bit resolution).
The data packets in a DMX signal are transmitted continuously, optionally with no delay between packets. As a result, the fewer channels used, the higher the possible refresh rate in the DMX control signal. Generally, the number of channels used in a given lighting system will vary according to the needs of the lighting system, however many lighting controllers use only a fraction of all available DMX channels. A more thorough description of the DMX-512 protocol is provided by John Huntington in
Control Systems for Live Entertainment
, Focal Press (1994), relevant portions of which are incorporated herein by virtue of this reference.
DMX control channels are generally assigned on a one-to-one basis corresponding to the various outputs (devices or features) that need to be controlled. Power is routed to the dimming or switching control devices and then internally distributed to multiple outputs. Conventional DMX control devices used in the lighting industry can control from one to many thousands of outputs, either one at a time or in any combination of multiple outputs. As a result, these devices are capable of providing considerable design versatility and flexibility, especially in controlling a number of lighting devices simultaneously. However, conventional DMX control systems may be wasteful and inefficient for certain lighting applications. In particular, in many lighting systems it is often desirable to activate a large number of loads (such as electroluminescent fibers), one at a time (or one subset at a time), in a desired sequence or order. When such sequencing applications are performed using conventional DMX lighting control, a separate relay (or other control device) and separate power supply are generally used to activate and energize each lighting device or load. Consequently, at any one time during the sequencing, all but one of the power supplies is idle and unused, resulting in significant technical and economic inefficiencies.
Sequencing control systems for driving a plurality of loads using a single power supply have been developed. For example, Weiner et al. in U.S. Pat. No. 4,215,277 describe a controller for sequentially energizing a plurality of light strings, each connected to an outlet receptacle via a triac switching device. A timing and logic circuit connects to a gating circuit for each triac switching device to provide selective energization of the triac and the corresponding light means connected to that triac. Similarly, Williams in U.S. Pat. No. 4,410,794 discloses a switching system for sequentially connecting an alternating current supply to a plurality of loads, in particular heater loads in an aircraft de-icing system. The system includes a computer for generating switch selection data, in the form of serial bits, to a distributor arrangement that decodes the selection data and provides control signals to switch devices that connect the loads to the supply. The distributor arrangement includes a circuit for inhibiting the supply of control signals to the respective switch devices unless the voltage of the supply phase connected by the device is substantially zero. The control signals are also time-advanced with respect to the zero voltage condition so that the switch devices can be placed in states in which they can connect a load prior to disconnection of a preceding load.
However, such prior art sequencing control systems are generally not compatible for operation with a DMX controller. This is disadvantageous since—given the wide spread adoption of the DMX protocol in the lighting industry—lighting designers, stage hands, theater electricians, architectural lighting consultants, and special effects designers are accustomed to programming DMX controllers and are familiar with the usage, distribution and maintenance of DMX systems. Compatibly with the DMX protocol also conveniently allows the same control signal used to effect the sequencing operation to also operate and activate other devices in a lighting system that are unrelated to the lighting devices being sequentially switched.
In addition, the intensity and color of electroluminescent loads, such as electroluminescent fibers, may be varied based on the voltage and frequency, respectively, of the power supply signal. For example, it may be desirable for the power supply signal to vary between 90-150 VAC and 400-2500 Hz to adequately exploit the potential for intensity and color variation in a fiber. However, the above described prior art sequencing control systems are generally
Fehd Brian
Huang Edmund Xuequn
Janowitz Marc
Wszolek, III Raymond C.
Production Solutions, Inc.
Rios Roberto J.
Sircus Brian
Winston & Strawn LLP
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