Backlight Unit Light Amount Adjustment for Brightness Uniformity
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Solution Overview
Problem
Backlight units using LEDs often suffer from uneven brightness due to direct and reflected light from LEDs, leading to image degradation, which existing technologies do not adequately address.
Innovation Solution
A light guide plate with a recess for housing LEDs and a light amount adjustment member, comprising an ink with specific optical properties applied to a transparent sheet, is used to adjust and limit the amount of direct and reflected light, ensuring uniform brightness distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a side emission type LED is used in a recess of the light guide plate, then the light can be guided to the liquid crystal panel, but a point-like light spot or bright line is produced at the light exit surface corresponding to the LED arrangement position, causing uneven brightness
Solution Approach 1:
The patent extracts the harmful direct light and reflected light from the light path by introducing a light amount adjustment member that selectively blocks these light components. The adjustment member is positioned to intercept light heading directly upward from the LED and light reflected by the recess inner wall or reflection sheet, removing these harmful factors from the light guide plate system.
Solution Approach 2:
The light amount adjustment member is applied locally at the light exit surface of the light guide plate corresponding to the LED arrangement position. This localized application allows the patent to address the specific problem of point-like light spots and bright lines at particular locations without affecting the overall light distribution uniformity across the entire display area.
2Productivity
If the light from LED is reflected inside the light guide plate, then the light can be emitted to the liquid crystal panel, but the reflected light produces a bright line at the light exit surface, degrading image quality
Solution Approach 1:
The patent extracts the harmful reflected light from the light path by positioning the light amount adjustment member to intercept light reflected by the recess inner wall or reflection sheet. This selective extraction allows the beneficial reflected light to be blocked while maintaining overall light utilization efficiency.
Solution Approach 2:
The patent converts the harmful reflected light that causes bright lines into a beneficial component by using the light amount adjustment member to control and redirect this light. The reflected light is intercepted and redistributed in a way that eliminates the bright line effect while maintaining light utilization efficiency.
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 effectively reduces uneven brightness and achieves a uniform brightness distribution across the display, enhancing image quality and light-use efficiency.
Implementation Method 1
a light guide plate for guiding a light from the light source to a liquid crystal panel side
Implementation Method 2
The light amount adjustment member is configured, for example, by applying an ink having predetermined optical properties to a transparent sheet
Data Source
AI summary
To provide a back light unit that reduces an uneven brightness and has a spatially uniform brightness distribution. According to an aspect of the present invention, the back light unit comprises an LED and a light guide plate for guiding light from the LED to a liquid crystal panel side, wherein a recess is provided on the back surface side of the light guide plate, wherein a plurality of LEDs are housed in the recess, and wherein a light amount limiting member is provided at a position facing the recess on s light exit surface side of the light guide plate. The light amount limiting member is configured, for example, by applying an ink with a predetermined optical property to a transparent sheet.