Optical Sheet Laminate for Backlight Luminance Uniformity
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Solution Overview
Problem
Portable information devices such as laptops and tablets require lower power consumption while maintaining high luminance, which existing direct-type backlight units fail to achieve efficiently.
Innovation Solution
An optical sheet laminate is integrated into the backlight unit, comprising a diffusion sheet with inverted quadrangular pyramid recesses and a pair of prism sheets with perpendicular prism directions, arranged at specific intersecting angles to enhance luminance uniformity and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional diffusion sheets with inverted pyramid recesses are used in direct-type backlight units, then light diffusion is achieved, but luminance uniformity and power efficiency are insufficient
Solution Approach 1:
The patent combines a diffusion sheet with inverted quadrangular pyramid recesses and a pair of prism sheets with perpendicular prism extending directions into an integrated optical sheet laminate. This merging of multiple optical components achieves superior luminance uniformity and power efficiency that cannot be attained by conventional single-type diffusion sheets alone.
Solution Approach 2:
The optical sheet laminate uses a composite structure comprising a diffusion sheet made of transparent resin with inverted quadrangular pyramid recesses and two prism sheets with perpendicular orientations. This composite material approach creates synergistic optical effects that improve luminance uniformity while reducing power consumption in direct-type backlight units.
2Illumination intensity
If the intersecting angle between recess arrangement direction and prism extending direction is near 0° or 90°, then manufacturing is simplified, but luminance output is reduced
Solution Approach 1:
The patent specifies that the intersecting angle between the arrangement direction of the inverted quadrangular pyramid recesses and the prism extending direction should be 20° to 70°. This parameter optimization achieves higher luminance output compared to conventional 0° or 90° alignments, while the relatively broad acceptable range (20°-70°) provides manufacturing tolerance that reduces precision requirements.
3Illumination intensity
If multiple optical sheets are layered to improve luminance uniformity, then optical performance is enhanced, but device thickness and complexity increase
Solution Approach 1:
The patent creates a composite optical sheet laminate integrating a diffusion sheet with inverted quadrangular pyramid recesses and two prism sheets with perpendicular orientations. This composite structure achieves enhanced luminance uniformity through the synergistic interaction of different optical components while maintaining a compact, integrated design that does not excessively increase device complexity.
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 higher luminance with lower power consumption by optimizing the angle between the diffusion sheet's recesses and prism sheets, improving luminance uniformity and reducing the backlight unit's size.
Implementation Method 1
an optical sheet such as a diffusion sheet or a prism sheet is used to diffuse light emitted from a light source such as a light emitting diode (LED) to improve uniformity of luminance and chromaticity
Implementation Method 2
a pair of prism sheets having prism extending directions perpendicular to each other
Data Source
AI summary
An optical sheet laminate 100 is to be incorporated into a backlight unit 40 having blue light sources 42. The optical sheet laminate 100 include: a diffusion sheet 43 having a first surface 21a having a plurality of recesses 22 having a substantially inverted quadrangular pyramid shape; and a pair of prism sheets 44 and 45 having prism extending directions perpendicular to each other. The diffusion sheet 43 includes one or a plurality of diffusion sheets in layers. The plurality of recesses 22 are arranged in a two-dimensional matrix, and the intersecting angle between an arrangement direction of the plurality of recesses 22 and the prism extending direction is 20° or more and 70° or less.