Display Controller Pulse Current Luminance Control
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Solution Overview
Problem
Existing display apparatuses using light sources like LEDs and lasers face limitations in adjusting luminance due to a lower limit in pulse width modulation, restricting the range of luminance adjustment, especially on the low end, leading to unstable light emission and limited grayscale range.
Innovation Solution
A display apparatus with a controller that adjusts the ON-period of pulse currents to the lower limit or longer, while reducing the current value, allowing stable light emission and expanding the luminance adjustment range by setting common current values for multiple light sources and switching current values in a stepwise manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the ON-period of pulse current is reduced to increase luminance adjustment range, then the adjustable luminance range is improved, but the light emission stability deteriorates
Solution Approach 1:
The patent changes the control parameter from pulse width (time) to current magnitude. By reducing the current value of pulse current while maintaining the ON-period at or above the lower limit, the system achieves lower luminance levels without compromising light emission stability. This parameter substitution resolves the contradiction by finding an alternative control variable that does not have the same stability constraints.
2Measurement precision
If the ON-period of pulse current is reduced to achieve finer luminance control, then the luminance control precision is improved, but the light source response reliability deteriorates
Solution Approach 1:
The patent substitutes current magnitude control for pulse width control to achieve fine luminance adjustment. By controlling the current value rather than the pulse duration, the system obtains precise luminance control without requiring sub-minimum pulse widths that would compromise light source response reliability.
3Adaptability or versatility
If the pulse current ON-period is set to the lower limit to expand luminance range, then the luminance adjustment flexibility is improved, but the light emission stability deteriorates
Solution Approach 1:
The patent maintains the ON-period at the lower limit or above to preserve light emission stability, while achieving luminance adjustment flexibility through current value modulation. By controlling current magnitude rather than pulse duration, the system gains flexibility without sacrificing the stability provided by adequate pulse width.
4Adaptability or versatility
If the current value of pulse current is reduced to achieve lower luminance, then the luminance adjustment range is improved, but the light emission intensity deteriorates
Solution Approach 1:
The patent accepts reduced light emission intensity as a necessary trade-off for achieving lower luminance levels and expanded adjustment range. By reducing current value, the system extends the low-end luminance range, accepting that minimum luminance settings will have correspondingly lower intensity. This is a deliberate parameter trade-off to achieve the desired control range.
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 enables stable light emission and a wider luminance adjustment range, enhancing image quality by allowing finer control over luminance and maintaining image quality without proportionate changes in current values, thus overcoming the limitations of existing technologies.
Implementation Method 1
a light source section that includes a plurality of light sources corresponding to at least any of the color light fluxes
Data Source
AI summary
A display apparatus includes: a display unit including a modulator that modulates a plurality of color light fluxes and a light source section that includes a plurality of light sources corresponding to at least any of the color light fluxes; a light source driver that supplies the light sources with pulse currents; and a controller that sets the cycle of each of the pulse currents and an ON-period of the pulses in the pulse current in accordance with the luminance of the light source, wherein when the luminance of any of the light sources is so set that the ON-period of the pulse current is shorter than a preset lower limit, the controller sets the length of the ON period of the pulse current to be equal to the lower limit or at a value longer than the lower limit and reduces the current value of the pulse current.