LED illumination control using simple digital command structure

Disclosed is an illumination controller for use with at least one three-color LED module. The illumination controller includes a command input, three color control outputs, and a processor. The command input receives a unitary illumination control command having first, second and third color level values, and a fade rate value. First, second, and third color control outputs pulse modulates respective first, second and third signals that powers an illumination level for each color. The processor, responsive to a control command, transitions the first color control output in accordance with the received command's first color level value and the fade rate value, transitions the second color control output in accordance with the received command's second color level value and the fade rate value, and transitions the third color control output in accordance with the received command's third color level value and the fade rate value. The three colors may be red, green, and blue.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to light-emitting diode (LED) illumination control using a simple digital command structure.

2. Description of the Prior Art and Related Information

LED illumination control is often accomplished by the modification of existing illumination control systems largely developed for AC incandescent lamps or similar devices. Such systems have relatively complicated command structures and modalities.

An example of an existing digital interface for illumination control system is DALI which is an acronym for Digital Addressable Lighting Interface. DALI typically uses a two-byte command having an address byte and a control byte. The data rate is typically 1200 bits per second. The control byte can have one of 512 different values, each representing distinct operations. Such digital interface may require several commands to accomplish relatively simple LED illumination control.

There is, therefore, a need for relatively simple technique for LED illumination control. The present invention provides the methods and apparatuses to meet these needs.

SUMMARY OF THE INVENTION

The present invention may be embodied in an illumination controller for use with at least one three-color LED module. The illumination controller includes a command input, three color control outputs, and a processor. The command input receives a unitary illumination control command having a first color level value, a second color level value, a third color level value, and a fade rate value. The first color control output pulse modulates a first signal that powers a first illumination level for a first color, the second color control output pulse modulates a second signal that powers a second illumination level for a second color, and the third color control output pulse modulates a third signal that powers a third illumination level for a third color. The processor, responsive to a unitary illumination control command received on the command input, transitions the first color control output in accordance with the received command's first color level value and the fade rate value, transitions the second color control output in accordance with the received command's second color level value and the fade rate value, and transitions the third color control output in accordance with the received command's third color level value and the fade rate value. The three colors may be red, green, and blue.

In more detailed features of the invention, the illumination controller may further include first and second front panel buttons. The processor may be configured with a pre-programmed illumination sequence that is controlled using the first and second front panel buttons. The first, second and third signals are below 24 volts. The unitary illumination control command may be an ASCII string that may be executed when the processor receives a carriage return character. The fade rate value may correspond to a fade rate greater than zero.

In other more detailed features of the invention, the command input may be a serial interface such as an RS-232 interface, or an RS-485 interface. Further, the command input may be a wireless interface.

The present invention also may be embodied in a method for controlling at least one three-color LED module. In the method, a unitary illumination control command is received. The unitary illumination control command has a first color level value, a second color level value, a third color level value, and a fade rate value. The illumination of the LED module is transitioned to a first illumination level for a first color by pulse modulating a first signal in accordance with the received command's first color level value and the fade rate value, is transitioned to a second illumination level for a second color by pulse modulating a second signal in accordance with the received command's second color level value and the fade rate value, and is transition to a third illumination level for a third color by pulse modulating a third signal in accordance with the received command's third color level value and the fade rate value.

The present invention also may be embodied in an apparatus for controlling at least one three-color LED module. The apparatus includes means for receiving a unitary illumination control command having a first color level value, a second color level value, a third color level value, and a fade rate value; means for transitioning to a first illumination level for a first color by pulse modulating a first signal in accordance with the received command's first color level value and the fade rate value; means for transitioning to a second illumination level for a second color by pulse modulating a second signal in accordance with the received command's second color level value and the fade rate value; and means for transitioning to a third illumination level for a third color by pulse modulating a third signal in accordance with the received command's third color level value and the fade rate value.

Further, the present invention may be embodied in a computer program product comprising computer readable medium storing: code for causing a computer to receive a unitary illumination control command having a first color level value, a second color level value, a third color level value, and a fade rate value; code for causing a computer to transition to a first illumination level for a first color by pulse modulating a first signal in accordance with the received command's first color level value and the fade rate value; code for causing a computer to transition to a second illumination level for a second color by pulse modulating a second signal in accordance with the received command's second color level value and the fade rate value; and code for causing a computer to transition to a third illumination level for a third color by pulse modulating a third signal in accordance with the received command's third color level value and the fade rate value.

DETAILED DESCRIPTION

With reference toFIGS. 1-3, the present invention may be embodied in an illumination controller10(FIG. 1) for use with at least one three-color LED module20. The illumination controller includes a command input, three color control outputs, CNTL1, CNTL2, and CNTL3, and a processor40. The command input30receives a unitary illumination control command200(FIG. 2) having a first color level value, a second color level value, a third color level value, and a fade rate value. The first color control output CNTL1pulse modulates a first signal that powers a first illumination level for a first color, the second color control output CNTL2pulse modulates a second signal that powers a second illumination level for a second color, and the third color control output CNTL3pulse modulates a third signal that powers a third illumination level for a third color. The processor40, responsive to a unitary illumination control command200received on the command input30, transitions the first color control output in accordance with the received command's first color level value and the fade rate value, transitions the second color control output in accordance with the received command's second color level value and the fade rate value, and transitions the third color control output in accordance with the received command's third color level value and the fade rate value. The three colors may be red, green, and blue.

The first, second and third signals may be below 24 volts. The unitary illumination control command200may be an ASCII string that may be executed when the processor40receives a carriage return character. The fade rate value may correspond to a fade rate greater than zero. The controller10may hold the outputs at the color levels defined by the command after the fade time.

The command input30may be a serial interface such as an RS-232 interface, or an RS-485 interface. Further, the command input may be a wireless interface.

The illumination controller10may further include first and second front panel buttons, B1and B2. The processor may be configured with a pre-programmed illumination sequence410that is controlled using the first and second front panel buttons.

The present invention also may be embodied in a method300for controlling at least one three-color LED module20. In the method, a unitary illumination control command200is received (step310). The unitary illumination control command has a first color level value, a second color level value, a third color level value, and a fade rate value (step320). The illumination of the LED module is transitioned to a first illumination level for a first color by pulse modulating a first signal in accordance with the received command's first color level value and the fade rate value (step330), is transitioned to a second illumination level for a second color by pulse modulating a second signal in accordance with the received command's second color level value and the fade rate value, and transitioned to a third illumination level for a third color by pulse modulating a third signal in accordance with the received command's third color level value and the fade rate value (step340).

The present invention also may be embodied in an apparatus10for controlling at least one three-color LED module. The apparatus includes means30for receiving a unitary illumination control command200having a first color level value, a second color level value, a third color level value, and a fade rate value; means40for transitioning to a first illumination level for a first color by pulse modulating a first signal in accordance with the received command's first color level value and the fade rate value; means40for transitioning to a second illumination level for a second color by pulse modulating a second signal in accordance with the received command's second color level value and the fade rate value; and means40for transitioning to a third illumination level for a third color by pulse modulating a third signal in accordance with the received command's third color level value and the fade rate value.

Further, the present invention may be embodied in a computer program product comprising computer readable medium50storing: code for causing a computer to receive a unitary illumination control command200having a first color level value, a second color level value, a third color level value, and a fade rate value; code for causing a computer to transition to a first illumination level for a first color by pulse modulating a first signal in accordance with the received command's first color level value and the fade rate value; code for causing a computer to transition to a second illumination level for a second color by pulse modulating a second signal in accordance with the received command's second color level value and the fade rate value; and code for causing a computer to transition to a third illumination level for a third color by pulse modulating a third signal in accordance with the received command's third color level value and the fade rate value.

The illumination controller10may provide RGB LED color control for a single lighting zone in smaller to mid-sized architectural spaces. The controller and the LED module(s)20may form one addressable segment100of a plurality of individually addressable and controllable segments corresponding to respective lighting zones. The controller may control common anode RGB components with input voltages below 24 volts (or it can alternatively control3separate single color LED strings simultaneously). The illumination controller utilizes pulse frequency modulation (PFM) to create smooth color fades and a logarithmic algorithm for more accurate color matching of eight-bit (256 level) RGB values. The unitary illumination control command200may include an address for the illumination controller.

The illumination controller may be wall mounted and may be installed in a standard single-gang electrical box (advantageously separate from any AC line voltage wiring) and may be manually operated with only two front panel buttons. A power supply is separate and should be specifically matched to the LED system being driven.

The illumination controller10may include a 6-position screw terminal connector. Typical screw positions may be labeled Vin, GND, Vout, R, G, B. Multiple parallel LED components may be wired in the same terminal block as long as the voltage requirements are compatible. Vin and GND are for the DC input from the power supply. (typically 6 volt minimum to 24 volt maximum) matched to the LED system. Vout may be for a common anode of the LED system. Further, R is for the Red channel, G is for the Green channel, and B is for the Blue channel.

The processor40may be a configurable communications controller, such as part number SX28AC/SS-G available from Parallax Inc. of Rocklin, Calif. The control outputs may each be implemented using a power MOSFET, such as part number FDP7030BL available from Fairchild Semiconductor of San Jose, Calif.

Manual operation of the illumination controller10may be accomplished using two buttons, B1and B2, and a predefined sequence of colors that will be displayed in a continuous loop (Loop Mode) at variable speeds. The sequence can be frozen (Freeze Mode) at any point in the loop.

Button1(the top button) toggles between Loop Mode and Freeze Mode. Button2(the bottom button) has different functions depending on the Mode. Upon power-up, the illumination controller is in Loop Mode with the pre-defined fade and hold times.

In Loop Mode, Button2acts as a time multiplier. Every time Button2is pressed (and released) in Loop Mode, the fade times and hold times are doubled until the multiplier is 32 (2, 4, 8, 16, 32). Then the multiplier goes back to 1 on the next press and release. To get directly back to a multiplier of 1 from any given multiplier, press and hold Button2for two seconds, then release. At any time during Loop Mode, a press and release of Button1will freeze the display (even in the middle of a color fade) and hold on that color indefinitely until another press of a button. While in Freeze Mode, each press and release of Button2will skip to the next defined color and stay there indefinitely until another press of a button.

To exit Freeze Mode and return to Loop Mode, press and release Button1. The loop will fade to the next color in the sequence and continue looping through the sequence with the time multiplier set before entering Freeze Mode. After multiple button presses, to determine which settings are current, a press and release of Button2will indicate whether or not the illumination controller is in Freeze Mode or Loop Mode (the colors will change with each press and release in Freeze Mode). If it is in Loop Mode, pressing and holding Button2for two seconds, then releasing, will to return to the default settings.

Fade time is the time it takes to reach the defined color from the previous color (1 to 60 seconds). Hold time is the time the color stays static before the fade to the next color (0.1 to 60 seconds). Set the fade and hold times to the shortest times you will possibly want and adjust later with the multiplier. Times may be defined to the nearest tenth of a second (e.g. 6.7 seconds).

The sequence410may be stored as a table in the processor40, or in a computer readable medium50. Each step of the sequence has a red level value420, a green level value430, a blue level value440, a fade time value450, and a hold time value460. The RGB levels correspond to a color description470.

The illumination controller may be extended to add control for a fourth color, such as amber, for a richer color selection. In such case, an amber level value would be added to the unitary illumination control command.

In one or more exemplary embodiments, the functions described may be implemented in hardware, software, firmware, or any combination thereof. If implemented in software as a computer program product, the functions may be stored as one or more instructions or code on a computer-readable medium. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store desired program code in the form of instructions or data structures and that can be accessed by a computer.