Shutter Glasses 3D Display Backlight Timing Control
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Solution Overview
Problem
Conventional shutter glasses based 3D display devices suffer from after image phenomenon due to crosstalk between left and right eyes, caused by the slow response speed of liquid crystal screens, which results in reduced luminance and flickering due to the need for adjusted timing of the backlight and shutter glasses.
Innovation Solution
The operation method adjusts the duty time of each block of the backlight unit to be between the response time of the liquid crystal to the current frame signal and the start of the subsequent frame signal, with equal duty time for all blocks, and individually changes pixel transmittance to maintain maximum luminance, using the formula Tm,pixel=Tm,pixel,0×TMax/TM to calculate the compensation value for the driving current, thereby reducing crosstalk and luminance reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the timing of the backlight and shutter glasses is adjusted to reduce crosstalk, then the after image phenomenon is reduced, but the activation time of the backlight and shutter glasses is reduced, resulting in reduced luminance and flickering
Solution Approach 1:
The backlight unit is divided into multiple vertical blocks (S1, S2, S3, S4, S5) that are scanned sequentially from top to bottom. Each block is activated independently with optimized timing, allowing the system to reduce crosstalk for each block while maintaining overall luminance through cumulative activation across all blocks.
Solution Approach 2:
The system pre-calculates and pre-positions the activation timing of each backlight block relative to the liquid crystal response time and shutter glass opening time. By anticipating the response delay of liquid crystal and the opening/closing time of shutter glasses, the system activates each block at the optimal moment to minimize crosstalk while ensuring sufficient luminance output.
2Object-affected harmful factors
If the duty time of each block is reduced to minimize crosstalk, then the after image is alleviated, but the overall luminance output decreases
Solution Approach 1:
The backlight unit operates in periodic scanning cycles, activating each vertical block sequentially rather than simultaneously. This periodic activation pattern allows each block to have a reduced duty time to minimize crosstalk, while the cumulative effect of all blocks activated in sequence maintains the overall luminance output required for display.
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 method effectively alleviates after image caused by crosstalk, maintains luminance, and achieves energy savings by controlling LED current and duty time, minimizing the crosstalk phenomenon while maintaining relative consistency in luminance across the liquid crystal panel.
Implementation Method 1
the response speed of a liquid crystal screen is excessively slow... After a pixel receives the driving voltage and is charged, the liquid crystal starts to respond. Due to the arrangement of pixel and the viscosity of liquid crystal, there is a period of response time, L0, for the liquid crystal to completely reach a desired stable condition
Implementation Method 2
illumination of a scanning back light unit (BLU)... a scanning operation is performed to sequentially, in a top to down manner, control the activation and duty time of each block of the back light unit
Data Source
AI summary
The present invention relates to an operation method of shutter glasses based 3D display device, which alternatively supplies left-eye and right-eye frame signals to a liquid crystal panel to drive the liquid crystal panel to respectively form left-eye and right-eye images, which cooperate with illumination of a scanning back light unit and timing control of the shutter glasses to simulate left and right eyes respectively with left-eye and right-eye signals for perception of a 3D image, wherein in a period of a current frame signal, duty time of each of blocks of the back light unit is located between the time when liquid crystal corresponding to the block completely responds after being driven by the current frame signal and the time when the liquid crystal corresponding to the block starts to respond as being driven by a subsequent frame signal. The operation method of shutter glasses based 3D display device according to the present invention alleviates after image caused by crosstalk between left and right eyes, compensates the reduction of luminance caused by shortening the duty time of each block of the back light unit, and thus achieves the purpose of saving energy.