Optical Sensor Positioning for Flicker Detection in Projection Displays
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Solution Overview
Problem
Existing projection display apparatuses face challenges in accurately and efficiently adjusting the common-electrode voltage (Vcom) to prevent flickers in liquid crystal display devices, particularly due to asymmetric AC voltage waveforms, which can lead to lower image quality, operational reliability issues, and increased costs associated with optical sensor installation and reinstallation.
Innovation Solution
A projection display apparatus with an optical modulator system that includes a liquid crystal display device, a reflective polarizer, a transparent polarizer, and an optical sensor positioned outside the optical path, allowing for accurate and rapid Vcom adjustments using differential signal processing and adaptive voltage calculations to minimize flickers across the entire projected image, including those caused by lamp flickers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an optical sensor is installed in the optical system to detect flickers, then flicker detection capability is improved, but the sensor's shade is projected onto the screen and installation complexity increases
Solution Approach 1:
The optical sensor is extracted from the main optical path and positioned in a separate location. The sensor detects light that has been reflected by the liquid crystal display device, rather than being placed directly in the projection path. This eliminates the sensor's shade from appearing on the screen while maintaining flicker detection capability.
Solution Approach 2:
The liquid crystal display device itself acts as an intermediary for flicker detection. Instead of placing a sensor in the optical path, the system uses the display device's reflected light as the detection medium, allowing indirect measurement of flickers without physical obstruction in the projection path.
2Measurement precision
If multiple optical sensors are installed to improve flicker detection accuracy, then measurement precision is improved, but device complexity and reinstallation difficulty increase
Solution Approach 1:
The single optical sensor serves multiple functions: it detects flickers in the projected image, measures light intensity for Vcom adjustment, and provides feedback for maintaining image quality. This multi-functionality eliminates the need for multiple specialized sensors, simplifying installation and reinstallation while maintaining detection accuracy.
3Manufacturing precision
If Vcom adjustment is performed to eliminate flickers, then image quality is improved, but the adjustment process becomes complex and time-consuming
Solution Approach 1:
The optical sensor provides real-time feedback on flicker conditions and light intensity to the control system. This feedback mechanism enables automatic or semi-automatic Vcom adjustment, reducing the manual trial-and-error process and minimizing the time required to achieve optimal image quality without flickers.
Solution Approach 2:
The system performs preliminary Vcom adjustment using the optical sensor's feedback before full projection begins. By pre-adjusting the common electrode voltage based on detected flicker patterns, the system eliminates flickers proactively rather than requiring continuous manual adjustment during operation.
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 enables precise and efficient Vcom adjustments, reducing flickers and improving image quality, while also simplifying reinstallation and reducing costs by minimizing the number of optical sensors and avoiding shade effects on the projected image.
Implementation Method 1
a reflective polarizer to allow the first linearly polarized-state bundle of rays to pass therethrough before the first linearly polarized-state bundle of rays is optically modulated by the liquid crystal display device whereas reflect a second linearly polarized-state bundle of rays originally involved in the incident bundle of rays in a first direction and reflect the second linearly polarized-state bundle of rays obtained by the optical modulation in a second direction different from the first direction
Implementation Method 2
a transparent polarizer to allow the second linearly polarized-state bundle of rays reflected by the reflective polarizer in the second direction to pass therethrough whereas reflect a first linearly polarized-state bundle of rays involved in the second linearly polarized-state bundle of rays reflected in the second direction
Implementation Method 3
an optical sensor to detect the first linearly polarized-state bundle of rays reflected by the transparent polarizer, the optical sensor being positioned outside an optical path of the second linearly polarized-state bundle of rays originally involved in the incident bundle of rays and reflected by the reflective polarizer in the first direction
Implementation Method 4
a liquid crystal display device to convert a first linearly polarized-state bundle of rays, with optical modulation based on an input video signal, into a second linearly polarized-state bundle of rays that is orthogonal to the first linearly polarized-state bundle of rays in polarization
Data Source
AI summary
A first linearly polarized bundle of rays of incident rays is converted by optical modulation with an input video signal into a second linearly polarized bundle of rays orthogonal to the first rays in polarization. The first rays pass through a polarizer before optically modulated. A second linearly polarized bundle of rays originally involved in the incident rays is reflected by the polarizer in a first direction. The second rays obtained by the optical modulation are reflected by the polarizer in a second direction. The second rays reflected in the second direction pass through another polarizer. A first linearly polarized bundle of rays involved in the reflected second rays is reflected by the other polarizer. The reflected first rays is detected by an optical sensor that is positioned outside an optical path of the second rays originally involved in the incident rays and reflected in the first direction.