Display Device Drive Current Generation Circuit
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Solution Overview
Problem
Conventional display devices with current drive type optical elements face challenges in achieving fast operating speed and stable image display due to low drive current during low gradation periods and susceptibility to external noise, which affects the charge and discharge time in signal wiring and results in unfavorable image quality.
Innovation Solution
A display device with a signal driver circuit that includes current generation circuits, such as gradation current generation and drive current generation circuits, using current mirror circuits and reference voltage generation to produce drive currents based on display signals, and a signal holding circuit to integrate gradation currents, ensuring efficient current supply and reducing noise impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional current drive method is used with changing current according to display data, then luminosity gradation is achieved, but charge and discharge time increases and operating speed decreases
Solution Approach 1:
The patent segments the drive current into multiple fixed gradation levels (first through fourth gradation currents) rather than using continuously variable current. Each segment corresponds to a specific luminosity level, allowing the display to achieve gradation effects while operating with discrete, predetermined current values that can be switched rapidly.
Solution Approach 2:
The patent changes the current parameter from continuously variable to discretely segmented fixed values. By establishing predetermined gradation currents with specific relationships (e.g., fourth gradation current = first gradation current + third gradation current), the system achieves both luminosity control and fast switching performance.
2Loss of energy
If low drive current is used during low gradation periods, then power consumption is reduced, but charge and discharge time increases and image quality deteriorates
Solution Approach 1:
The patent establishes predetermined gradation currents in advance, including a fifth gradation current that is set to a predetermined value regardless of the display data period. This preliminary preparation of current levels ensures that even during low gradation periods, sufficient current is available to maintain fast charge and discharge times and prevent image quality deterioration.
Solution Approach 2:
The patent dynamically selects from multiple predetermined gradation currents based on display requirements. The system can switch between different current levels (first through fifth gradation currents) to optimize both power consumption and image quality for different display scenarios, rather than being constrained to a single current level.
3Power
If conventional current generation circuit is used, then drive current is supplied to display pixels, but external noise affects the circuit and stabilizes electric potential slowly
Solution Approach 1:
The patent introduces a current selection circuit as an intermediary between the current source and the display pixels. This intermediary circuit selects from multiple predetermined gradation currents and supplies the appropriate current to the display pixels, isolating the current source from direct exposure to display data variations and reducing susceptibility to external noise.
4Illumination intensity
If individual write-in currents are generated for each display pixel, then luminosity gradation is achieved, but device complexity increases
Solution Approach 1:
The patent creates a universal current generation system where a single current source generates multiple gradation currents (first through fifth gradation currents) that can be used for all display pixels. The current selection circuit serves multiple pixels simultaneously, reducing overall device complexity compared to individual current generation circuits for each pixel.
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 solution enhances operating speed and improves display response characteristics, achieving favorable image quality by reducing the time required for drive current generation and stabilizing luminosity gradation, even at low current levels.
Implementation Method 1
a signal driver circuit which supplies the display signals to a plurality of signal lines, and comprises current generation circuits which generate drive currents based on display signals
Data Source
AI summary
A display device that displays image information in response to a digital display signal includes a display panel signal lines and scanning lines which intersect at right angles with each other, and a plurality of display pixels with optical elements arranged near the intersecting points of the signal lines and scanning lines. A signal driver circuit has a plurality of current generation circuits including a drive current generation circuit for generating drive current from a plurality of gradation currents based on the display signal value supplied to each of the scanning lines, a scanning driver circuit for sequentially applying a scanning signal to each of the scanning lines for setting the selection state of each line of each display pixel, and a gradation current generation circuit for generating gradation currents according to each display signal bit at least based on a constant predetermined reference current.