Fixed Duration Frequency Light Intensity Control
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Solution Overview
Problem
Existing methods for controlling light intensity, such as pulse width modulation (PWM) and variable pulse frequency, suffer from inaccuracies due to capacitance and inductance effects in electronic circuitry, leading to non-linear current flow and visible defects in displays and lighting systems.
Innovation Solution
A light intensity control method using pulses of fixed duration and frequency, where the number of pulses in a timing cycle is varied to control the total current flow through a light source, ensuring precise and linear intensity adjustment without the distortions caused by PWM or variable frequency methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If pulse width modulation (PWM) is used to control light intensity by varying pulse duration, then light intensity control is achieved, but the total current flow becomes non-linear due to capacitance and inductance effects in the circuit
Solution Approach 1:
The patent applies periodic action by using fixed-duration pulses at a fixed frequency (e.g., 1 kHz) to drive the light source, rather than varying pulse width. The dimming effect is achieved by controlling the number of pulses within a timing cycle, not by changing individual pulse characteristics. This periodic approach with fixed parameters eliminates the capacitance and inductance distortion problems that plague variable pulse width methods.
Solution Approach 2:
The patent segments the timing cycle into discrete fixed-duration pulses, where each pulse delivers a consistent current charge to the light source. By dividing the control period into identical, repeatable pulse units, the system ensures that each pulse contributes equally to the total current flow, creating a linear relationship between pulse count and total current, thereby eliminating the non-linearity introduced by circuit capacitance and inductance.
2Illumination intensity
If variable pulse frequency is used to control current flow, then light intensity can be adjusted, but timing accuracy is reduced due to analog circuitry in voltage controlled oscillators
Solution Approach 1:
The patent replaces the mechanical/analog voltage controlled oscillator system with a digital timing mechanism. Instead of using analog circuitry to generate variable frequencies, the system uses a digital counter or timer that can precisely generate fixed frequency pulses (e.g., 1 kHz) with high timing accuracy. This substitution of digital for analog timing eliminates the inherent inaccuracies of VCO-based frequency generation.
3Illumination intensity
If pulse duration is varied in PWM to control intensity, then brightness adjustment is possible, but visible defects occur due to non-linear current flow through the light source
Solution Approach 1:
By using fixed-duration pulses at a fixed frequency rather than variable pulse widths, the system creates consistent, repeatable current delivery to the light source. The periodic nature of the fixed pulses ensures uniform charging of circuit capacitance and consistent current flow through inductance, eliminating the non-linear effects that cause visible defects in PWM-based systems.
Solution Approach 2:
The patent changes the control parameter from pulse width (duration) to pulse count within a timing cycle. Instead of varying the duration of individual pulses, the system maintains fixed pulse parameters and controls brightness by adjusting how many pulses occur within a complete timing cycle. This parameter change from temporal duration to temporal quantity eliminates the capacitance and inductance distortion problems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides digitally precise and accurate control of light intensity, eliminating visible defects and ensuring consistent current flow, as the persistence of human vision perceives increasing intensity without flicker or stepping, achieving a linear relationship between intensity and current flow.
Implementation Method 1
the light source may be implemented using a light emitting diode or an array of light emitting diodes
Data Source
AI summary
A method and circuit to control the intensity of lights, illumination fixtures, and displays using pulses of a fixed duration and a fixed frequency (FD/FF) is provided. In particular, the method may be used to control one more light sources. By varying the number of pulses in a control burst, the total current flowing through the light source may be precisely controlled providing greater accuracy than other methods, such as, for example, PWM or variable pulse frequency. The FD/FF technique may be used in conjunction with any number of light sources, and finds particular application in LED displays and for any type of LED illumination fixture.