Backlight Luminance Sensor Integration on LCD Substrate
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Solution Overview
Problem
Existing liquid crystal display (LCD) systems require user-adjustment of backlight luminance, which can lead to improper adjustment and deterioration over time, affecting display quality.
Innovation Solution
Integration of a luminance sensor on the LCD substrate, formed in the same process as pixel transistors, to detect and maintain constant backlight luminance through a control circuit generating drive signals, ensuring accurate and automatic adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a luminance sensor is integrated on the LCD substrate formed in the same process as pixel transistors, then automatic and accurate backlight luminance maintenance is achieved, but device complexity increases
Solution Approach 1:
The luminance sensor is merged with the pixel transistor formation process on the same substrate. The sensor uses the same thin-film transistor structure and manufacturing steps as the display pixels, integrating the sensing function into the existing device architecture without requiring separate sensor fabrication or additional substrates.
Solution Approach 2:
The thin-film transistor structure serves dual purposes: as the driving transistor for display pixels and as the sensing element for luminance detection. The same gate, source, and drain electrodes are used to control both pixel operation and sensor response to backlight luminance.
2Adaptability or versatility
If luminance adjustment is performed after shipping, then user adaptability is improved, but adjustment accuracy deteriorates due to aged deterioration
Solution Approach 1:
The luminance sensor performs preliminary detection of backlight luminance immediately after manufacturing. The control circuit uses this initial measurement to set the optimal drive current for the backlight, establishing accurate luminance levels before the device is shipped to the user.
Solution Approach 2:
The luminance sensor continuously monitors backlight luminance during device operation and provides feedback to the control circuit. The control circuit adjusts the drive current based on this feedback to compensate for aged deterioration, maintaining stable luminance throughout the device lifespan without user intervention.
3Ease of manufacture
If thermistor-based luminance control is used, then manufacturing simplicity is maintained, but manufacturing precision of luminance control deteriorates
Solution Approach 1:
The mechanical/thermal-based thermistor control system is replaced with an electronic sensor-based system. The luminance sensor directly measures optical output and converts it to electrical signals for precise digital control, eliminating the indirect thermal coupling and response delays inherent in thermistor-based approaches.
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 solution allows for precise and automatic maintenance of backlight luminance, even with aged deterioration, reducing user intervention and maintaining display quality without increasing costs or thickness.
Implementation Method 1
a luminance sensor formed on one of the substrates (this substrate is referred to as the first substrate), the luminance sensor and thin film devices as pixels being formed on the first substrate in the same process, the luminance sensor that detects the luminance of the backlight
Implementation Method 2
the diffusing portion that diffuses color rays emitted from the light emitting device array and generates white light
Implementation Method 3
the light guide portion that equally guides the color rays emitted from the light emitting device array to the entire surface of the diffusion portion
Data Source
AI summary
A liquid crystal display apparatus and backlight adjustment method are provided.Backlight luminance sensors 111A to 111D are disposed in the vicinity of four outer corners of an effective screen of an LCD panel 121. Each of the backlight luminance sensors 111A to 111D detects the luminance of each of three primary colors. A backlight unit is composed of a three-primary LED array and a light diffusion unit. Transistors of the backlight luminance sensors and transistors of a pixel portion are formed on the same substrate in the same process. When a transistor is irradiated with backlight in its sufficient off region, an off current occurs due to light excitation. Since the value of the off current corresponds to the luminance of the rays of backlight that irradiates the transistor, the luminance of the backlight is detected with an output voltage into which the off current is converted. As a result, the luminance of the backlight is kept constant.