Dual Objective Lens Optical Pickup for BD and HD Compatibility
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Solution Overview
Problem
Existing optical pickup apparatuses are cumbersome and large due to the need for separate light sources for different high-density optical discs, such as BD and HD, which limits design flexibility and temperature characteristics.
Innovation Solution
An optical pickup apparatus with two objective lenses, each optimized for a specific disc type, allowing for efficient recording and reproduction of information on both BD and HD discs using a single light source, while maintaining compact size and improved temperature stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate light sources are provided for BD and HD objective lenses, then recording and reproducing compatibility for different high density discs is achieved, but device complexity and size increase
Solution Approach 1:
The patent merges two separate light sources into a single shared light source that serves both BD and HD objective lenses. The light source unit includes a BD light source and an HD light source that can be selectively used depending on which disc type is being processed, eliminating the need for completely separate optical paths while maintaining compatibility for both disc formats
Solution Approach 2:
The single light source unit is designed to perform multiple functions by selectively activating either the BD light source or HD light source based on the disc type. This universal light source configuration allows the same optical path to serve both BD and HD recording/reproducing operations, reducing overall device complexity
2Device complexity
If a common objective lens is used for BD and HD, then device structure is simplified, but temperature characteristics deteriorate due to restricted design freedom
Solution Approach 1:
The patent segments the objective lens system into two distinct lenses: a BD objective lens optimized for BD discs with 0.1mm protective substrate thickness and NA 0.85, and an HD objective lens optimized for HD discs with 0.6mm protective substrate thickness and NA 0.65-0.67. Each lens can be independently designed for optimal temperature characteristics without compromise
Solution Approach 2:
The patent implements a dynamic switching mechanism that selects which objective lens to use based on the disc type being processed. The objective lens switching unit can move the appropriate lens into the optical path, allowing each lens to operate in its optimal design condition while maintaining overall system simplicity
3Reliability
If separate objective lenses are provided for BD and HD, then temperature characteristics and design freedom are secured, but device size increases
Solution Approach 1:
The patent arranges the BD objective lens and HD objective lens in a nested or overlapping configuration where their optical paths share common components. The lenses are positioned such that they can be sequentially moved into the same optical path, effectively nesting their functional spaces and reducing the overall volume required for the objective lens unit
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
Enables compatible recording and reproduction of information on multiple disc types with enhanced temperature characteristics and reduced size, addressing the limitations of previous apparatuses.
Implementation Method 1
a first objective lens for converging a first light flux from the first light source on an information recording surface of a first optical information recording medium
Data Source
AI summary
An optical pickup apparatus for conducting at least recording or reproducing of information on two types of optical information recording media having protective substrates with different thicknesses, includes: a first light source for emitting a first light flux with a wavelength λ1; a first objective lens for converging the first light flux on an information recording surface of a first optical information recording medium when the optical pickup apparatus reproduces or records information for the first optical information medium; and a second objective lens for converging the first light flux on an information recording surface of a second optical information recording medium when the optical pickup apparatus reproduces or records information for the second optical information medium, wherein effective diameters of the first objective lens and the second objective lens are substantially same.