CROSS-REFERENCE TO RELATED APPLICATIONS:

None

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT; Not Applicable

1. Field of the Invention

The present invention relates to providing digital communication using AC power lines via phase switching.

2. Description of the Related Arts

There are two major trends impacting dimming and other lighting control applications. First, home automation, which holds the promise to improve user comfort while at the same time reducing energy consumption generally entails the consolidation of functions that have been historically autonomous, for example, lighting, HVAC and security. Secondly, the general availability of lighting bulbs and fixtures, which have greater operational efficiencies than standard incandescent bulbs but are not inherently compatible with conventional dimming switches. These inolude LED and compact fluorescent bulbs and fixtures. First, home automation systems are designed to control the condition of an environment such as a home or commercial space. They are implemented using a number of connected devices such as lighting fixtures, switches, HVAC devices, temperature sensors, ambient light sensors, gas sensors, and end user control devices. Furthermore, a digital communication infrastructure must be in place in order to provide connectivity between all of the system components. There are many barriers facing the wide-scale adoption of home automation systems, including the high cost of retrofitting the existing infrastructure with components and devices as well as the high learning curve of configuring, operating and maintaining these systems.

Secondly, conventional dimmer switches, which are widely deployed in residential and commercial spaces, where designed to control the light output intensity of incandescent bulbs, but are not inherently compatible with bulbs that have greater operational efficiency (lumens per watt). This has limited the adoption of these high efficiency altematives, which include LED and fluorescent bulbs and fixtures.

A number of technologies have been developed in order to provide a

communications link between appliances and end users (or home automation systems). One such example is Power line communications (PLC), which transmits a digital signal by impressing a modulated carrier signal on to the existing AC mains wiring system as illustrated by FIG 1a. There are many different standards-based and proprietary Implementations of PLC technologies differ in operating parameters such as of modulation scheme and carrier frequency bands. However, all PLC technologies share the same basic principals in order to modulate a high frequency signal onto the low frequency (50/60HZ) power distribution system. There are a number of technical challenges in doing so as the power distribution wiring infrastructure have a limited ability to carry high frequency signals. The impressed carrier signal is either directly coupled on the AC power line via a capacitor or transformer. The main barriers to entry of PLC systems include the high cost of transmitter and receiver devices and components and the high over-head of PLC networking protocols requiring a microprocessor and memory sub-system.

One variant of modulating a digital signal onto the AC power line infrastructure has been developed by Insteon in an effort to reduce the noise Injection to the AC input voltage waveform. Insuring the safe and reliable operation of the AC power distribution system is a key concern of utility providers and governmental agencies such as the FCC, necessitating a great deal of scrutiny of any technology that introduces high frequency signals. In order to minimize the noise during periods when the of AC current is highest, Insteon provides a solution which injects the modulated data signal during the time that the current on the AC power-line waveform reverses polarity, otherwise referred to as the power- line zero crossing. Therefore, INSTEON packets are transmitted during the zero crossing quiet time, as shown in the FIG 1b. Although resulting in less noise being introduced to the AC mains, the main barriers to entry of this solution are similar to other PLC systems, which include the high cost of transmitter and receiver devices and components and the high over-head of PLC networking protocols requiring a microprocessor and memory sub-system.

As mentioned above, a simple end widespread of using the AC mains waveform as a means adjust the operation of an appliance is the phase-switch dimmer switches used to alter the AC power-line waveform to adjust the V-R S of the downstream input voltage, thus adjust the light output intensity of an

incandescent bulb or lighting fixture. FIG 2 illustrates a typical block diagram of prior art dimmer switches. The basic operational principal of a conventional dimmer switch utilize phase switching In order to vary the RMS voltage (V-RMS) which is Input to the incandescent bulbs, since the light output level of incandescent bulbs vary directly with V-RMS. Dimmer switch 200 includes triac 201 , which is connected in series with AC input voltage 203 and bulb 204. Triac 201 is placed in the OFF or open state during periods of the AC voltage cycle, W

effectively disconnecting bulb 204 from AC input voltage source 203 during periods of the cycle. The duration in which triac 201 remains in the OFF state is set by variable resistor 202. The end user adjusts variable resistor 202 until the desired light output from bulb 204 is achieved.

FIG 3a, 3b, and 3c illustrate the basic operational waveforms of prior art dimmer switch 200. FIG 3a shows the Input voltage of bulb 204 when the maximum tight output intensity is desired. In this case, triac 201 remains In the ON state and no phase switching occurs. FIG 3b shows the input voltage of bulb 204 when moderate light output intensity is desired by lowering V-RMS (as compared with FIG 3a). FIG 3b shows an approximately 45 degree phase switching. FIG 3c shows the input voltage of bulb 204 when low light output intensity is desired by further reducing V-RMS (as compared with FIG 3a and 3b). FIG 3c shows an approximately 90 degree phase switching.

This has proven to be an effective and simple method to control the light output intensity of incandescent bulbs because they present a resistive load and they light output intensity varies directly with V-RMS.

However, as mentioned above, lighting technologies have been introduced which have greater operational efficiency than incandescent bulbs are not inherently compatible with dimmer switches that employ adjusting the Input voltage using phase switching, LED and fluorescent bulbs and lighting fixtures are two prominent examples, as neither an LED device nor a fluorescent tube can be directly connected to the AC input source,

FIG 4 illustrates an example of an LED lighting fixture 404 coupled to AC input source 203 via dimmer switch 200. As mentioned, LED device 405 cannot be connected directly to the AC input source and requires LED controller and driver 406. As the light output intensity of an LED device varies directly to the forward current, one of the primary functions of LED controller and driver 406 is to

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TUTE SHEET RULE 26 regulate the forward current of LED device 405. As the user adjusts variable resistor 202 to lower the light output intensity, dimmer switch 200 increasing phase switching in order to lower the V-RMS Input to LED lighting fixture 404. However, LED controller and driver 406 provides a regulated output current to LED device 405 maintaining a constant light output intensity regardless of the value of V-RMS,

In order to provide dimming capabilities for direct Incandescent bulb

replacements, some LED and fluorescent bulbs have added the capability to adjust the light output intensity based on adjustments made by a phase switched dimmer switch. Again using an LED lighting fixture as an example, FIG 5 LED lighting fixture 504 coupled tD AC input source 203 via dimmer switch 200, The voltage input to LED lighting fixture 504 is monitored by input voltage detect 507, A number of prior art detection techniques are employed, including phase angle, V-RMS, or duty-cycle measurements. Once the input voltage has been detected, a dimming factor signal is input to LED controller and driver 506 in order to make appropriate adjustments to the output light intensity.

This has proven to be a reliable "work-around" because 1) there are many existing phase switch dimmer switches already Installed in residential and commercial spaces, 2) the relatively low cost of phase switch dimmer switches, 3) the ease of installation of phase switch dimmer switches, 4) the familiarity of phase switch dimmer switches by end users, and 5) incandescent bulbs are still available in the marketplace. However, as incandescent bulbs begin to be phased out due to the low operating efficiencies as compared bulbs and fixtures based on newer technologies, employing dimming functionality by using phase switching to adjust the V-RMS will no longer be necessary. Furthermore, there are significant downsides of phase switching on each AC cycle, including unnecessary losses Incurred by the dimmer switch itself, (e.g. switching losses incurred by the triac device on each and every AC cycle) and the decreased operational efficiency of the lighting fixture due to a decreased input voltage.

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SUBSTITUTE SHEET RULE 26 Furthermore, phase switching increases total harmonic distortion -(THD) on the power utility grid.

Another significant disadvantage resulting from using prior art dimmer switches is that wiring infrastructure coupled to the dimmer switch is dedicated to the controlling an incandescent bulb, and/or incandescent bulb replacement. This further adds to the wiring and Infrastructure complexity.

What is needed in the art is the ability to provide signaling required for such purposes as transmitting a dimming setting from a dimmer switch to a lighting fixture. Furthermore, it is desired to provide signaling with the highest degree of energy efficiency and positive environmental impact, ease of installation (new construction and existing structures), ease of use for end users, and system cost.

SUMMARY OF THE INVENTION

Embodiments of the present invention include a transmitter in which the transmitter is capable of transmitting a digitally encoded message on an AC waveform, where using phase switching of an AC cycle and/or half cycle to determine the value of a bit. Further embodiments of the present invention include a receiver in which the receiver is capable of receiving and decoding a digitally encoded message, where phase switching of a cycle, or half cycle, of an AC waveform has been employed to determine the value of a bit.

The transmitter and receiver are employed in a standard AC power wiring system in residential or commercial buildings. The transmitter and receiver are employed to send and receive a message from an end user or application system (e.g. home automation system), to a device or appliance.

In one non-limiting embodiment, the transmitter and receiver are used to set the light output intensity of a lighting bulb or fixture to the desired setting. The desired light output intensity may be determined by an end user or by a home automation system.

In one non-limiting embodiment the lighting fixture is comprised of LED devices.

In one non-llmltlng embodiment the lighting fixture contains fluorescent bulbs.

The features and advantages described in the specification are not all inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, should be noted that the language used In the specification has been principally selected for readability and Instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the embodiments of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings.

FIG. 1a illustrates waveforms of prior art Power-Une Communications Systems (PLC)

FIG. 1b illustrates waveforms of prior art Power-Line Communications Systems (PLC)

FIG. 2 illustrates the conventional wiring configuration of a conventional dimmer switch and an incandescent bulb.

FIGS. 3a, 3b, and 3c illustrate typical waveforms from a conventional dimmer switch.

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SUBSTITUTE SHEET RULE 26) FfG. 4 illustrates the conventional wiring configuration of a conventional dimmer switch and an LED bulb.

FIG. 5 illustrates the conventional wiring configuration of a conventional dimmer switch and an LED bulb employing dimming capabilities.

FIG. 6 illustrates the wiring configuration of a transmitter/switch and a

receiver/LED bulb according to one embodiment of the present invention.

FIGS. 7a, 7b illustrate typical waveforms from a transmitter according to one embodiment of the present invention.

FIG. 8 illustrates typical waveforms from a transmitter according to one embodiment of the present invention.

FIG. 9 illustrates the wiring configuration of a transmitter/switch and multiple receiver/appliance devices according to one embodiment of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

The Figures (FIG.) and the following description relate to preferred embodiments of the present invention by way of illustration only. It should be noted that from the following discussion, alternative embodiments of the structures and methods disclosed herein will be readily recognized as viable alternatives that may be employed without departing from the principles of the claimed invention.

Reference will now be made in detail to several embodiments of the present invention(s), examples of which are illustrated in the accompanying figures. It is noted that wherever practicable similar or like reference numbers may be used in the figures and may indicate similar or like functionality. The figures depict embodiments of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods Illustrated herein may be employed without departing from the principles of the invention described herein.

As will be explained in more detail below with reference to the figures, the transmitter and receiver system and a method according to various embodiments of the present invention (1) a transmitter digitally encodes a message on an AC waveform ueing phase switching of a cycle, or half cycle (2) a receiver for receiving and decoding digital signal on an AC waveform where the detection of phase switching of a cycle, or half cycle, determines the value of the bit (3) receiver, as part of a client device or appliance, responds to the transmitted signal with the desired response or setting as desired by an end user or application system. Furthermore, when the transmitter is not transmission mode, the AC waveform is unaffected by the transmitter and no phase switching is executed.

FIG 6 illustrates the wiring configuration of one embodiment of the present invention where receiver/LED bulb 604 Is connected to AC input voltage 203 via transmitter/switch 600. A dimmable LED lighting application Is used as an example to Illustrate the transmit and receive function of the present invention, however other applications are applicable (e.g. HVAC and security systems), Transmitter/switch 600 is connected in series with AC input voltage 203 and receiver LED bulb 604. Transmitter/switch 600 has three operational modes, (1) OFF' mode, (2) messaging mode, and (3) 'ON' mode. In the 'OFF' mode, triac 601 is placed in an open state, effectively disconnecting receiver/LED bulb 604 OFF from AC input voltage 203. A triac device is desirable because of the relatively low cost and high reliability, but other comparable switching devices may be employed. In the messaging mode, transmitter/switch 600 will determine the desired light output intensity desired by the end user and a digitally encoded message ilJ be generated. The digital message may be stored in a look-up- table, created by machine language running on a micro-controller, or by other prior art digital message generation methods. The digital message is transmitted by phase switching of the AC voltage signal provide by AC input voltage 203. Receiver/LED bulb 604 includes a digital decoder, which monitors the incoming AC input voltage and decodes the transmitted digital message containing the desired setting. This may Include, amongst other things, light Intensity output and color saturation settings. The desired settings are input to the LED controller and driver, which directly provides the appropriate drive current to the LED devices. The message mode is used primarily during initial start-up or when a change to the setting is input by the end user. The 'ON' mode is used when a message is not being transmitted. During this time, triac 601 is placed in the 'closed' position, directly connecting AC input voltage 203 and receiver/LED bulb 604. This allows control parameters to be transmitted without the downside impact of unnecessary energy loss in the switch as well as harmonic distortion to the AC power grid.

The following table illustrates a non-limiting example the present invention where the digital message that is transmitted contains the desired dimming settings of receiver/LED bulb 604. As mentioned, a look-up table (LUT) may be used to simplify the cost and configuration of the system. End user sets the desired dimming setting via transmitter/switch 600. The desired setting is encoded in a digital message, which is transmitted and by transmitter/switch 600 and received by receiver/LED bulb 604. In the example below, the adjustment settings are defined by a 5-bit word, which results in seven discrete dimming settings and/or seven color adjustment setting and are described by a LUT such as the following:

Bit [0:1]: initialize, if bit [0:1]=00, start encoding

Bit [21: Status; if bit [2]*0, adjust coloring; if bit 121=1 , adjust dimming level

Bit [3:5]: adjust the level for dimming or coloring

10 UBSTITUTE SHEET RULE 26 Bit

0 1 2 3 4 5

Initialize Status Message Description

0 0 1 0 0 0 level 0

0 0 1 0 0 1 Level 1

0 0 1 0 , 1 0 Level 2

0 0 J 0 1 1 Level s Dimming

0 0 1 1 0 1 Level 4

0 0 1 1 1 0 Level s

0 0 1 1 1 1 Level 6

0 0 0 0 0 0 Level 0

0 0 0 0 0 1 Level 1

0 0 0 0 1 0 Level 2

0 0 0 0 1 1 Level 3 Coloring

0 0 0 1 0 1 Level 4

0 0 0 1 1 0 Level s

0 0 0 1 1 1 Level 6

FIGs 7a and 7b illustrate the basic operational waveforms of the present invention. As shown by FIG 7a, transmitter/switch 600 uses each half cycle of the AC input voltage to transmit one data bit. In this example, when

transmitter/switch 600 enables phase switching during a half cycle period, the bit value is set at Ό\ To set the bit value to Ί', phase switching is disabled, essentially leaving the AC waveform unchanged during that half cycle. The waveform shown In FIG 7b Is the full wave rectified signal from FIG 7a.

FIG 8 further Illustrates the waveforms of the present invention during the messaging mode and the 'ON' mode. As you can see, only during the messaging mode is phase switching of the AC input voltage enabled. Once the digital message has been transmitted, transmitter/switch 600 returns to the ON' mode, disabling phase switching, leaving the AC power-line waveform from AC input voltage 203 unaffected. Furthermore, although not shown, the messaging mode includes provisions for standard preamble/payioad packet formats.

11 ET RULE 26 FIG 9 illustrates the wiring configuration of one embodiment of the present invention where multiple devices are connected to AC Input voltage 203 via transmitter/switch 900, including receiver/appliance 904 and receiver/appliance 905. Both receiver/appliance 904 and receiver/appliance 905 are capable of decoding digitally encoded messages and can be contain a unique client identifier. Therefore, the application or end user can individually address each device. For example, if receiver/appliance 904 and receiver/appliance 905 were lighting fixtures, the light output Intensity pf each device can be individually adjusted. Furthermore, because the messaging mode is used only for small periods of time both on duration and frequency, the AC input signal is largely unaffected. This makes it practical to couple standard devices 906 (devices without digital communication capabilities) to transmitter/switch 900 in order to provide AC input power.

As illustrated by FIG 7, a digital bit value of "Γ results from a non-phase switched half cycle and a digital bit value of Ό' results from a leading-edge 90 degree switched half cycle. However, the present Invention allows for alternative phase switching to be used for a digital bit value of '1' and Ό'. For example, a unique phase switching characteristic may be used to represent a digital bit value of Ί", Including (a) leading-edge or traillng-edge phase switching as well as (b) the phase angle between 0 degrees and 180 degrees. For example, a digital bit value of Ύ may be represented by a leading-edge 45 degree phase switching, and a digital bit value of '0' may be represented by a trailing^edge 90 degree phase switching.

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TUTE SHEET RULE 26