Standalone light emitting diode (LED) controller

Patent metadata

Field	Value
Publication number	US-9894733-B1
Application number	US-201615387798-A
Country	US
Kind code	B1
Filing date	Dec 22, 2016
Priority date	Dec 22, 2016
Publication date	Feb 13, 2018
Grant date	Feb 13, 2018

Abstract

Embodiments are provided that include a light emitting diode (LED) controller connectable to a matrix of LEDs. A start code is received via at least one input pin, and a selected curve profile is retrieved from a programmable local memory in response to receipt of the start code, wherein the programmable local memory stores a set of curve profiles, each of which is associated with a different start code. A set of coefficients of a polynomial calculator are initialized to a set of values defined in the selected curve profile, wherein the set of values represent a light output curve. A sequence of light intensity values are calculated according to the polynomial calculator, and at least one pulse width modulation (PWM) signal is generated based on the sequence of light intensity values, wherein the at least one PWM signal controls light output of at least one LED.

First claim

What is claimed is:

1. A matrix light emitting diode (LED) system comprising:
a first LED controller connectable to a first matrix of LEDs, the first LED controller comprising:
at least one input pin configured to receive a first start code value;
a programmable local memory configured to store a set of curve profiles, wherein each curve profile stores a different set of coefficient values, and curve profile is associated with a different start code value;
a processor coupled to the at least one input pin and the programmable local memory, the processor configured to:
in response to receipt of the first start code value:
initialize a set of coefficients of a polynomial calculator with a set of values defined in a selected curve profile associated with the first start code that is retrieved from the programmable local memory, wherein the set of values represent a desired light output curve, and
output a set of voltage levels based on a presently calculated light intensity value output by the polynomial calculator; and

a set of pulse width modulation (PWM) generators configured to output a set of PWM signals based on the set of voltage levels corresponding to the presently calculated light intensity value, wherein each PWM signal controls light output of a respective LED of the first matrix of LEDs.

2. The matrix LED system of claim 1 , wherein a second start code value indicates a stand-by mode, wherein the processor is configured to output a light intensity value of 0% brightness as the presently calculated light intensity value to each of the set of PWM generators during the stand-by mode.

3. The matrix LED system of claim 1 , wherein the at least one input pin comprises a pair of binary input pins configured to receive one of four different start code values, and the set of curve profiles comprises a maximum of three different curve profiles.

4. The matrix LED system of claim 1 , wherein the programmable local memory is coupled to a programming interface comprising two or more pins configured to write a number of curve profiles to the programmable local memory.

5. The matrix LED system of claim 1 , wherein
each PWM generator comprises:
a comparator configured to receive a digital oscillating signal and a respective voltage level of the set of voltage levels, wherein the respective voltage level controls a duty cycle of the PWM signal.

6. The matrix LED system of claim 1 , wherein
the LED controller further comprises:
a plurality of switches coupled to the matrix of LEDs, wherein
each PWM signal is provided to a control gate electrode of a respective switch coupled in parallel with a respective LED in the matrix of LEDs, and
each PWM signal controls a switching period of the respective switch to turn the respective LED on and off to implement a time-averaged brightness level of the light output of the respective LED according to the desired light output curve.

7. The matrix LED system of claim 1 , wherein
the polynomial calculator, when initialized with the set of coefficients, is configured to implement a polynomial function that describes the desired light output curve, wherein the polynomial function defines light intensity values as a function of index number.

8. The matrix LED system of claim 1 , wherein
each of the set of curve profiles further stores a scaling parameter value that indicates a number of time units over which the desired light output curve extends, and
the processor is further configured to:
initialize a scaling parameter of the polynomial calculator with the scaling parameter value stored in the selected curve profile.

9. The matrix LED system of claim 1 , wherein
each of the set of curve profiles further stores a fade directional indicator value that indicates one of a fade-in light output effect or a fade-out light output effect, and
the processor is further configured to:
initialize a counter of the polynomial calculator to sequentially increment an index value from a minimum value to a maximum value to generate a set of index numbers in a first sequential order, in response to a first fade directional indicator value stored in the selected curve profile, and
initialize the counter of the polynomial calculator to sequentially decrement an index value from the maximum value to the minimum value to generate a set of index numbers in a second sequential order opposite the first sequential order, in response to a second fade directional indicator value stored in the selected curve profile.

10. The matrix LED system of claim 1 , wherein
the polynomial calculator is further configured to:
calculate a sequence of light intensity values at an update rate equivalent to a frequency utilized by the PWM generators to generate the PWM signals, and

the processor is further configured to:
output sets of voltage levels to the set of PWM generators in a sequential manner based on the sequence of light intensity values.

11. The matrix LED system of claim 1 , wherein
the first LED controller further comprises:
a fault detection circuit configured to detect one or more possible failures including: an open circuit failure in the first matrix of LEDs, a short circuit failure in the first matrix of LEDs, and a temperature excursion; and
a fault output line, wherein
the processor is configured to output a fault code on the fault output line in response to a detected failure.

12. The matrix LED system of claim 1 , wherein
the processor is further configured to:
for each light intensity value calculated:
provide a voltage level corresponding to the light intensity value to the set of PWM generators in a successively delayed manner, wherein
the selected curve profile further includes a delay factor that defines a delay time,
the processor is configured to output the voltage level to a first PWM generator at a first time,
the processor is configured to output the voltage level to a second PWM generator at a second time after the first time, where the second time is delayed after the first time by the delay time.

13. The matrix LED system of claim 12 , wherein
the successively delayed manner achieves a wiping light output effect at the first matrix of LEDs, wherein the desired light output curve is implemented at a first LED channel positioned at one end of the first matrix of LEDs and is sequentially propagated through each LED of the first matrix of LEDs to a last LED channel positioned at another end of the first matrix of LEDs, according to a channel directional indicator.

14. The matrix LED system of claim 1 , wherein
receipt of the first start code value triggers the first LED controller to output a first sequence of voltage levels to the set of PWM generators on the first LED controller, wherein the first sequence of voltage levels correspond to a first sequence of light intensity values calculated by the polynomial calculator on the first LED controller.

15. The matrix LED system of claim 14 , wherein
the first LED controller further comprises:
a first synchronization pin connectable to a second LED controller that in turn is connectable to a second matrix of LEDs, wherein
the first synchronization pin is configured to output a start signal to the second LED controller, and
the start signal triggers the second LED controller to output a second sequence of voltage levels to a second set of PWM generators on the second LED controller, wherein the second sequence of voltage levels correspond to a second sequence of light intensity values calculated by a polynomial calculator on the second LED controller.

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Assignees

• Nxp Bv

Inventors

• Buthker Henricus Cornelis Johannes
• Mediavilla Pons Emiliano
• Boezen Hendrik

Classifications

• H05B45/00 Primary

  Circuit arrangements for operating light-emitting diodes [LED] · CPC title

• H05B45/48 Primary

  having LEDs organised in strings and incorporating parallel shunting devices · CPC title

• H05B45/10

  Controlling the intensity of the light · CPC title

• H05B47/155

  Coordinated control of two or more light sources · CPC title

• H05B33/083

  Electricity · mapped topic