Adaptive filter for lighting assembly control signals

• US 8,508,330 B1
• Filed: 05/25/2010
• Issued: 08/13/2013
• Est. Priority Date: 05/25/2009
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Godbole, Kedar, Ng, Chi Wang
• Primary Examiner(s): Nguyen, Nam V
• Application Number:
  US12/786,754
• Time in Patent Office: 1,176 Days
• Field of Search: 340/3.1, 340/3.44, 340/3.9, 340/7.32, 340/12.34, 315/209, 315/224, 315/225, 315/307, 315/291, 362/249.02, 362/430
• US Class Current: 340/3.1
• CPC Class Codes: H05B 45/20 Controlling the colour of the light

Abstract

A processing circuit may include a command source that receives at least one feature input control signal for a lighting fixture; and an adaptive filtering mechanism that generates a filtered control signal in response to the input control signal, wherein the adaptive filtering mechanism varies a filter function in response to at least a temporal state of the input control signal.

Claims

1. A processing circuit comprising:

a command source configured to receive at least one feature input control signal for a lighting fixture; and

an adaptive filtering mechanism configured to generate a filtered control signal in response to the input control signal, wherein the adaptive filtering mechanism is configured to generate the filtered control signal according to a relatively slower speed of response to the feature input control signal responsive to a first difference between a filtered control signal value and a feature input control signal value and generate the filter control signal according to a relatively faster speed of response to the feature input control signal responsive to a second difference between the filtered control signal value and the feature input control signal value.

2. The processing circuit of claim 1, wherein:

the adaptive filtering mechanism varies its characteristics as a function of a rate of change of at least one of the signals.

3. The processing circuit of claim 1, wherein:

the adaptive filtering mechanism varies a speed of response to the input signal according to a believability factor that is a function of at least the input control signal and the filtered control signal.

4. The processing circuit of claim 1, wherein:

the adaptive filtering mechanism switches between filtering at least two different frequency ranges.

5. The processing circuit of claim 1, wherein:

the adaptive filtering mechanism comprises a state variable filter.

6. A lighting system comprising:

at least one lighting device configured to vary an illumination feature in response to a filtered control signal;

a control signal source configured to generate an input control signal to change the illumination feature; and

an adaptive filtering mechanism configured to vary a filtering operation in response to the current illumination feature and the input control signal to generate the filtered control signal, wherein the adaptive filtering mechanism is configured to generate the filtered control signal according to a relatively slower speed of response to the input control signal responsive to a first difference between a filtered control signal value and an input control signal value and generate the filter control signal according to a relatively faster speed of response to the input control signal responsive to a second difference between the filtered control signal value and the input control signal value.

7. The lighting system of claim 6, wherein:

the illumination feature is intensity; and

the input control signal is a dim command that varies an intensity of light emitted from the lighting device.

8. The lighting system of claim 6, wherein:

the control signal source is a dimming controller that selectively passes only a portion of an alternating current (Ae) signal to generate the input control signal.

9. The lighting system of claim 6, wherein:

the at least one lighting device comprises a light emitting diode (LED) lighting fixture having at least one LED element arranged in series with an inductor and a control switch, the control switch being activated in response to the filtered control signal.

10. A method comprising:

varying a filtering function applied to an input illumination control signal to generate a filtered illumination control signal in response to the received illumination control signal and at least a current state of an illumination system, wherein the varying of the filtering function includes generating the filtered illumination control signal according to a relatively slower speed of response to the illumination control signal responsive to a first difference between a filtered illumination control signal value and an illumination control signal value and generating the filtered illumination control signal according to a relatively faster speed of response to the illumination control signal responsive to a second difference between the filtered illumination control signal value and the illumination control signal value.

11. The method of claim 10, wherein:

varying the filtering function includes increasing a speed of a filter response based on a difference between a desired state of the illumination system represented by the input illumination control signal and the current state of the illumination system.

12. The method of claim 10, wherein:

the received illumination control signal is a dimming command and the state of the illumination system is an intensity of light emitting diode (LED) light sources of the system.

13. The method of claim 10, wherein:

varying the filtering function includes generating the filtered illumination control signal according to a relationship

y[n]F1[y[n−

1], y[n−

2] . . . y[n−

k], x[n], x[n−

1] . . . x[n−

j]}

where “

y”

is the filtered illumination control signal, “

x”

is the input illumination control signal and is selected from the group consisting of;

a scalar value and vector value, “

F 1”

is a function, “

n−

1” and

“

n”

are time values at samples n, n−

1 etc, and where j and k are distinct positive numbers.

14. The method of claim 10, wherein:

varying the filtering function includes generating the filtered illumination control signal based on a believability function that includes the relationship

y[n]F2[y[n−

k],x[n−

j],a]

where “

y”

is the filtered illumination control signal, “

F2”

is a function, “

x”

is the input illumination control signal, n, j and k are real numbers indicating one or more time samples, and “

a”

is a function of any of;

at least temporal value of x, at least one temporal value of y, or time.

15. The method of claim 14, wherein:

the parameter a is chosen from a set of pre calculated coefficients.

16. The method of claim 10, wherein:

varying the filtering includes generating the filtered illumination control signal according to a state variable function that includes the form

s[n+1]=A*s[n−

k]+Bx[n−

j]

y[n]=C*x[n]+D*x[n]

where “

s”

is a state of the illumination system, “

y”

is the filtered illumination control signal, “

x”

is the input illumination control signal, and A, B, C, and D are matrices and n, k and j are real numbers indicating one or more time samples of their respective values.

17. The method of claim 16, wherein:

at least one of the matrices is a function of the input illumination control signal and a current filtered illumination control signal.

18. The method of claim 10, further including:

generating the input illumination control signal by altering a phase angle <

1>

, where <

I>

is a portion a 180 degree half cycle of an AC signal, angle <

I>

starting at a zero cross over point of the AC signal.

19. The method of claim 10, further including:

generating the input illumination control signal with a lighting dimmer switch.