LED Light Therapy Device PWM Brightness Control
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Solution Overview
Problem
Existing light therapy devices lack the ability to adjust brightness and operate modes effectively, making them unsuitable for targeted clinical treatments and are often expensive and not suitable for portable or changing environments.
Innovation Solution
A light therapy device with a control unit that uses pulse width modulation of a constant operating current to adjust LED brightness, combined with a low-pass filter to eliminate flicker and harmonics, allowing for customizable light settings and modes, including RGB LED control for additive color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pulse width modulation is used to control LED brightness, then brightness adjustability is improved, but flicker and harmonics are generated
Solution Approach 1:
A low-pass filter is introduced as an intermediary component between the PWM signal source and the LED. This filter mediates the interaction by allowing the PWM signal to pass through while blocking the harmful high-frequency harmonics and reducing flicker, thus protecting the LED from adverse effects while maintaining brightness control functionality.
Solution Approach 2:
The patent changes the frequency parameter of the PWM signal to optimize performance. By operating at a sufficiently high frequency (above 100 Hz), the flicker becomes imperceptible to the human eye. Additionally, the low-pass filter modifies the frequency spectrum by attenuating harmonics above the cutoff frequency, thereby changing the frequency characteristics to eliminate harmful effects.
2Reliability
If constant current is used to operate LEDs, then reliable operation is improved, but brightness cannot be adjusted
Solution Approach 1:
The patent applies periodic pulse width modulation to the constant current supply. Instead of a continuous constant current, a periodically pulsed current is supplied where the duty cycle of the pulses controls the average brightness. This periodic action maintains the reliability benefits of constant current operation while enabling brightness adjustment through variable duty cycles.
3Device complexity
If simple LED arrangement is used, then device complexity is reduced, but therapeutic effectiveness is limited
Solution Approach 1:
The patent applies local quality by using a diffuser element positioned over the LED array. This diffuser creates local variations in light distribution, scattering the light to achieve more uniform illumination across the therapy area. This simple additive component locally modifies the light properties to enhance therapeutic effectiveness without significantly increasing device complexity.
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
The device provides flicker-free, adjustable brightness light emission, enabling targeted therapeutic effects and flexibility in treatment settings, making it suitable for various environments and clinical applications.
Implementation Method 1
a first order low pass filter, in particular an RC element, is connected in front of the individual LED
Implementation Method 2
a plurality of LEDs in the light housing, which emit light through an opening in the light housing
Implementation Method 3
a diffuser sheet of diffusing sheet material is positioned over the LEDs to provide uniform light emission
Data Source
Figure 1
Figure 2~4
Figure 3A~3B
AI summary
The light therapy device has a light housing (1) and multiple light emitting diodes arranged in the housing. The light is emitted through an opening in the light housing. The luminosity of the light emitting diodes is controlled by a pulse width modulated operating current.