Optical Disc Dummy Groove Pitch Adjustment
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Solution Overview
Problem
Disc-shaped optical information recording media exhibit a brightness difference near the inner peripheral edge due to varying groove depths and pitches in the reflecting layer, leading to decreased reflection intensity and noticeable annular portions when viewed from the label surface.
Innovation Solution
The optical information recording medium features a light-transmitting substrate with pre-grooves and dummy grooves, where the pitch, depth, or half-width of the dummy grooves is adjusted relative to the pre-grooves to minimize the reflection intensity difference, often by increasing the pitch or reducing the depth of dummy grooves, thereby reducing the brightness variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the reflecting layer is extended to dummy grooves beyond the inner peripheral edge of the recording layer, then the image forming region is extended, but the groove depth increases causing decreased reflection intensity and brightness
Solution Approach 1:
The patent applies local quality by making the pitch of dummy grooves larger than that of pre-grooves in the inner peripheral region where the reflecting layer is extended. This local modification of groove pitch compensates for the increased groove depth effect, maintaining uniform reflection intensity across the extended image forming region while preserving the benefit of extended area.
2Illumination intensity
If the pitch of dummy grooves is increased to compensate for depth effects, then reflection intensity is improved, but the groove structure becomes more complex
Solution Approach 1:
The patent changes the physical parameter of groove pitch specifically in the dummy groove region, making it larger than in the pre-groove region. This parameter modification provides a simple yet effective means to control reflection intensity without introducing complex structural elements, maintaining manufacturing feasibility while achieving the desired optical performance.
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 adjustment effectively decreases the brightness difference as seen from the label surface, enhancing the uniformity of visible light reflection and reducing the noticeable annular portions near the inner peripheral edge.
Implementation Method 1
the intensity of reflection of visible light from the surface (per unit area) of the reflecting layer 4 provided on the dummy grooves 2b is lower than that from the surface of the reflecting layer 4 provided on the pre-grooves 2a
Data Source
AI summary
An optical information recording medium includes an optical disk body including a light-transmitting substrate, a recording layer provided on a main surface of the light-transmitting substrate over a region in which pre-grooves are formed and a portion of a region in which dummy grooves are formed, and a reflecting layer provided over the recording layer and a region of the light-transmitting substrate in which the recording layer is not provided; and an ink receiving layer provided on the label surface side of the optical disc body. The dummy grooves provided in at least a portion of the region in which the dye material is not applied have a pitch larger than that of the pre-grooves, are shallower than that of the pre-grooves, or have half-width less than that of the pre-grooves.