Field Sequential Display Voltage Reduction
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Solution Overview
Problem
Liquid crystal display devices using the field sequential type driving method face high operating voltages, leading to increased power consumption, particularly in PDLC type displays which require about 60V compared to the 10V of general liquid crystal displays.
Innovation Solution
The implementation of a display device structure that applies a constant voltage to all pixels before common inversion, reducing the amplitude of the signal supplied to the transistor gate by approximately 40% and the required withstand voltage, using a combination of frame inversion, field inversion, and common inversion driving methods to manage voltage polarity and amplitude.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If field sequential type driving method is used to achieve color display without color filter, then resolution and light transparency are improved, but operating voltage increases to about 60V
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the voltage levels applied to the liquid crystal elements during different time periods. Specifically, a first voltage is applied during a first time period and a second voltage is applied during a second time period, allowing the system to maintain color display capability while reducing the peak voltage requirement from 60V to a lower level, thus resolving the contradiction between resolution and operating voltage.
2Illumination intensity
If field sequential type driving method is used to perform color display by sequentially lighting light sources, then color display quality is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic action by dividing the display period into multiple time periods, where different voltages are applied to different sets of liquid crystal elements in sequence. This field sequential driving method allows color display to be achieved through time-multiplexed illumination control, maintaining color display quality while managing power consumption through efficient temporal scheduling of voltage application.
3Illumination intensity
If high voltage is applied to PDLC liquid crystal elements to achieve transparency, then display performance is improved, but transistor stress and reliability deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-charging the liquid crystal elements to a first voltage level before the main display period, and then applying a second voltage level during the display period. This staged voltage application allows the system to achieve the necessary transparency and display performance while avoiding the application of excessively high voltages that would cause transistor stress, thus improving reliability.
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 reduces the operating voltage and power consumption of the display device, simplifies the circuit structure, and enhances the operational margin by minimizing voltage fluctuations and transistor stress.
Implementation Method 1
an electro-optical element arranged sandwiched between the plurality of first electrodes and the plurality of second electrodes, and changing optical characteristics based on an applied voltage
Implementation Method 2
In the case when no voltage is applied, the PDLC is in an opaque white state, and in the case when a voltage is applied, the PDLC becomes transparent
Data Source
AI summary
A display device including applying a positive polarity first voltage with respect to the plurality of first electrodes to the plurality of second electrodes, and applying a voltage according to an image signal to one of the plurality of first electrodes in a first time period, applying a negative polarity second voltage with respect to the plurality of first electrodes to the plurality of second electrodes, and applying a voltage according to an image signal to one of the plurality of first electrodes in a second time period, and applying to the plurality of first electrodes a common voltage larger than a minimum value of an allowable range of a voltage according to an image signal applied to one of the plurality of first electrodes and determined in a range equal to or less than the first voltage in a third time period.