Abstract:
A light fixture with multiple dimming capabilities is provided. More particularly, a device, system and method are provided for automatically sensing the presence of dimming signals from one or more power/voltage dimmers (i.e., phase-cut dimmers) and one or more data controllers providing dimming control signals according to a digital data controller protocol, and determining a priority between the two, for applying a dimming signal.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims benefit of Provisional Patent Application No. 62/096,063, filed on Dec. 23, 2014; that application being incorporated herein, by reference, in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a light fixture and, more particularly, to a light fixture capable of selectively varying the light intensity in response to variations in power and/or data. 
     Description of the Related Art 
     The use of dimmers to vary the intensity of light is common in light fixtures used in homes and commercial facilities and for other applications, such as stage lighting. Dimming of incandescent lights is typically accomplished by varying the power/voltage delivered to the lamp, through a process known as “phase-cut” or rheostat dimming, by sliding a switch or turning a knob. However, dimming of light emitting diodes (LEDs), which are being used in place of incandescent lights in many applications due to their greater efficiency and decreased operating costs, as well as some other light technologies, cannot be accomplished by varying the power/voltage in the same manner as incandescent lights. Because LEDs operate at significantly lower powers/voltages than incandescent lights, conventional dimmers (i.e., “triac dimmers” or “legacy dimmers”) designed for incandescent lights do not function properly with LEDs, resulting in a significantly smaller dimming range. Instead, the intensity of LED fixtures is typically varied by sending data control signals to the LED drivers. 
     Light fixtures used in theaters, studios, auditoriums and other facilities for stage and studio lighting and other similar purposes, have traditionally used incandescent light sources and, therefore, the facilities have been built with power/voltage dimming systems. The inability of LED light fixtures to function properly with these legacy power dimming systems has been an impediment to the adoption of LED light fixtures in these existing facilities that have already invested significant resources to build the current infrastructure. These facilities and installations using incandescent lights and legacy power dimmers cannot simply add dimmable LED fixtures into the existing power infrastructure without also making substantial infrastructure changes to power the LED fixtures, because the LED fixtures will not operate properly, as the power in the existing infrastructure is varied to dim the incandescent lights co-existing in the system. This has resulted in facilities with incandescent lights continuing to use incandescent light fixtures rather than incorporating and transitioning to more cost effective LED fixtures. It also results in facilities with incandescent lights not having access to advanced lighting fixtures, features and technologies that are only offered with LEDs. 
     Accordingly, there is a need in the art for a new and improved lighting fixture that is capable of varying the light intensity using traditional incandescent light power/voltage variation dimmers and/or data control signals. Any such fixture should be capable of consistently varying the light intensity throughout the full dimming range regardless of whether the dimming is being driven by power/voltage variation or data control signals. 
     U.S. Patent Application Publication No. 2009/0184662 to Given et al., discloses dimming signal generation circuits used for differing types of power dimming signals, including dimming directly from a phase cut input AC line, DC voltage level dimming (e.g., 0-10V DC dimming) and/or pulse-width modulated (PWM) dimming. Additionally, the dimming level detection circuit of Given et al., may be configurable by component selection and/or by connection to different input connectors associated with at least two different types of power dimming signals. 
     Additionally, U.S. Pat. No. 8,643,304 to Hamel et al., discloses a dimming protocol detection for a light fixture for detecting a dimming protocol from a plurality of dimming protocols, such as a 0-10 volt lighting control, digital addressable lighting interface (DALI), digital multiplex (DMX512) lighting interface, a remote device management (RDM) interface, or a combination thereof. Additionally, Hamel et al., discloses a light fixture including a light dimming control module configured to control the plurality of lights based on the detected dimming protocol. 
     These prior art systems are structured for use with either power dimming signals or dimming control protocols. Neither discloses or suggests the ability to be used with both conventional power dimmers (i.e., phase cut dimmers) and data control dimmers, nor do they disclose or suggest the need for an LED light fixture that can be installed in legacy power dimming systems, and can operate in response to both traditional power dimming signals and digital data control signals, so that these existing facilities can begin to adopt LED light fixtures, and benefit from the advanced features, functionality and performance offered by LED light fixtures, without the need for significant investment in new infrastructure. 
     Accordingly, what is needed is a light fixture capable of automatically sensing the presence of dimming signals from power/voltage dimmers (i.e., phase-cut dimmers) and data control protocol dimmers and determining a priority for applying a dimming signal. For example, a light fixture is needed that can be used with legacy power dimmers and digital data control protocol dimmers such as, among others, digital multiplexing (DMX512 or DMX), ACN, ArtNet, KlingNet, Dali or any other data control protocol now known or later developed. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention is particularly suited to overcome those problems which remain in the art in a manner not previously known or contemplated. It is accordingly an object of the invention to provide a device, system and method for automatically sensing the presence of dimming signals from one or more power/voltage dimmers (i.e., phase-cut dimmers) and one or more data controllers providing dimming control signals according to a digital data controller protocol, and determining a priority between the two for applying a dimming signal. In one particular embodiment, the device is embodied in a light fixture. In another particular embodiment of the invention, the device determines whether a power dimming signal is less than a threshold to determine whether or not to vary the light intensity of a light based on the signal from a power dimmer or from a data controller. In a further embodiment, priority is given to a dimming signal from the power dimmer, over a dimming signal from a data controller. 
     Although the invention is illustrated and described herein as embodied in a light fixture with multiple dimming capabilities, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. 
     The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing background, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings. For the purpose of illustrating the invention, there is shown in the drawings an exemplary embodiment that is presently preferred, it being understood however, that the invention is not limited to the specific methods and instrumentality&#39;s disclosed. Additionally, like reference numerals represent like items throughout the drawings. In the drawings: 
         FIG. 1  is a simplified diagram showing a light fixture with multiple dimming source capabilities in accordance with one particular embodiment of the invention; and 
         FIG. 2  is a basic flow diagram showing a method of operation for a fixture, such as the fixture of  FIG. 1 , in accordance with one particular embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Before explaining the disclosed embodiment of the present invention in detail, it is to be understood that the invention is not limited in its application only to the details of the particular arrangement shown since the invention is capable of other embodiments. Also, the terminology used herein is for the purpose of description and not of limitation. 
     Referring now to  FIG. 1 , a light fixture  10  is provided that is capable of varying the light intensity output by the light fixture  10 , in response to dimming control signals received from one or more traditional (i.e., legacy) incandescent light voltage variation dimmer switches  40  and one or more digital data controllers  30 . The incandescent light voltage variation dimmer switch  40  is hereinafter referred to as the power dimmer or legacy dimmer  40 , and the dimming signal received from the power dimmer  40  is hereinafter referred to as the power dimming signal  42 . 
     The digital data controller  30  provides digital data control signals  32  in accordance with a data control protocol, such as, but not limited to, digital multiplexing (DMX512 or DMX), ACN, ArtNet, KlingNet, Dali or other known or later developed data control protocols. In one preferred embodiment, the digital data controller  30  is a digital multiplexing protocol (DMX) controller. DMX is a standard protocol for digital communication commonly used to control stage lighting and theatrical effects, including, but not limited to, moving lights, color changing lights and fog machines, and for color changing LED applications. Although a DMX controller is described in a preferred embodiment, it should be appreciated that the data control signal  32  may be provided in accordance with any other digital data control protocol now known or later developed. 
     The power dimmer  40  may be any technology now known or later developed structured to dim incandescent lights and other light technologies, including, but not limited to, a bidirectional triode thyristor or bilateral triode thyristor (TRIAC), a silicon-controlled rectifier (SCR), a rheostat or an insulated gate bipolar transistor (IGBT). Additionally, the power dimmer  40  may be connected to the fixture  10  through legacy wiring suitable for use with an incandescent fixture and power dimmer  40 , or other wiring. 
     The light fixture  10  includes separate input ports  12 ,  14  to receive the data dimming signal  32  from the data controller  30  and the power dimming signal  42  from the power dimmer  40 , respectively. Note that that is not meant to be limiting, as the data dimming signal  32  from the data controller  30  and/or the power dimming signal  42  from the power dimmer  40  may also be received by the light fixture  10  by wireless means without departing from the scope or spirit of the present invention. 
     The light fixture  10  includes, preferably therein, a control unit or module  20  structured to sense the presence of dimming signals  32 ,  42  from the data controller  30  and power dimmer  40 . The control module  20  is particularly configured to analyze the dimming/control inputs  32 ,  42  and vary the light intensity output  55  responsively. In one particular embodiment of the invention, the control module  20  includes hardwired circuitry configured to particularly analyze the dimming signals  32 ,  42  and produce an output lighting signal  55 . In another particular embodiment, the control module includes a microprocessor or microcontroller configured by software stored in non-transitory memory of the control module  20  that, when executed, particularly configures the microprocessor or microcontroller to perform the analysis of the input signals and the varying of the output signal. In a further embodiment of the invention, a combination of hardwired circuitry and a microprocessor or microcontroller particularly configured by software is used to perform the analysis of the dimming signals  32 ,  42  and to vary the light intensity output  55  according to the methods of the present invention. 
     More particularly, referring now to  FIGS. 1 and 2 , the control module  20  analyzes the dimming signals  32 ,  42  to selectively send the data dimming signal  32  or the power dimming signal  42 , or a dimming signal derived from the data dimming signal  32  or the power dimming signal  42 , to a light source  50 , based on predefined selection criteria programmed into the control module  20 . In one preferred embodiment, the control module  20  receives and analyzes the dimming signals  32 ,  42  to determine on which basis to vary the light intensity output  55 . Step  110 . More particularly, if the control module  20  detects that a power dimming signal  42  is present at the input port  14 , the control module  20  measures the power level of that power dimming signal  42 . Step  120 . The measured power level of the power dimming signal  42  is then compared to a predefined threshold or level T set in the control module  20 . Step  130 . In one preferred embodiment, the predefined level T is eighty percent (80%) of the standard power level of electrical equipment in the particular geographic area (typically based on 120 volts or 240 volts). However, it should be appreciated that the predefined level may be set at any other desired level deemed appropriate to sense whether adequate power is present to vary the intensity of the particular light source throughout the full range of the light. Setting a threshold permits the system to account for voltage variations (voltage fluctuations, brown-outs, etc.) in the AC line voltage, without having the control module  20  attribute them to dimming. 
     If the measured power level of the power signal  42  is less than the predefined threshold T, the control module  20  will select the power dimming mode  44  and transmit the power dimming signal  42  to the light source  50 . Step  140 . If it is determined in step  130  that the power level of the power dimming signal  42  measured by the control module  20  is equal to or greater than the predetermined level T, the control module  20  will then sense whether or not a data dimming signal  32  is present. Step  150 . As discussed above, the data dimming signal is a digital data control signal according structured according to a digital data protocol such as, but not limited to, DMX. Step  150 . If no data dimming signal  32  is present, the control module  20  will select the power dimming mode  44  and transmit the power dimming signal  42 , or a signal based on the power dimming signal  42 , to the light source  50 . Step  140 . If the measured power was greater than or equal to the threshold and a data dimming signal  32  is present, the control module  20  will select the data dimming mode  34  and transmit the data dimming signal  32 , or a signal based on the data dimming signal  32 , to the light source  50 . The light intensity output  55  will, therefore, be set according to the dimming signal selected by the control module  20 , in accordance with the method described herein. 
     In a preferred embodiment, the light source comprises one or more LEDs or other solid-state lighting (SSL) devices. However, it should be appreciated that other light sources may be used within the spirit and scope of the present invention. 
     Although the embodiment described above measures the power level of the dimming signal, it should be appreciated that a voltage level or current level may alternatively be measured and compared with a predefined voltage or current level, respectively, in step  130 , to determine whether to use the dimming signal from the legacy dimmer  40  (the prioritized selection) or the data dimming signal  32  from a data controller  30 . As can be seen, the present invention gives priority to the power dimming signal  42  over that of the data dimming signal  32 . In other words, if a power dimming signal  42  is present and below a threshold T, that signal is used to adjust the light intensity output, regardless of whether a data dimming signal  32  is also present. Only if the power dimming signal  42  is greater than or equal to the threshold T, does the control module  20  determine if a data dimming signal is present and should be used. 
     Although the embodiment of the lighting fixture  10  of the present invention describes the sensing of just two independent dimming control signals, one from a data controller  30  and the second from an incandescent light voltage variation dimmer switch  40 , it should be appreciated that the dimming control signals can be sent from any other dimming control sources now known or later developed or can be received by the light fixture  10  of the present invention from more than two dimming control sources without departing from the scope or spirit of the invention. 
     While the invention has been described, disclosed, illustrated and shown in various terms of certain embodiments or modifications, which it has presumed in practice, the scope of the invention is not intended to be, nor should it be deemed to be, limited thereby and such other modifications or embodiments as may be suggested by the teachings herein are particularly reserved, especially as they fall within the breadth and scope of the claims here appended. Accordingly, while a preferred embodiment of the present invention is shown and described herein, it will be understood that the invention may be embodied otherwise than as herein specifically illustrated or described, and that within the embodiments certain changes in the detail and construction, as well as the arrangement of the parts, may be made without departing from the principles of the present invention as defined by the appended claims.