Optical Pickup Device Dichroic Mirror Multi-Wavelength Integration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional optical pickup devices require separate optical systems for CD, DVD, and BD due to differences in wavelength, making it challenging to miniaturize and save space in devices like laptop personal computers, where a single device must support multiple disk types.
Innovation Solution
An optical pickup device with a dichroic mirror that reflects and transmits light for CD/DVD and transmits BD light, using a three-wavelength laser diode setup with dichroic film layers to optimize reflectance and transmittance, allowing shared optical components and maintaining detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate optical systems are used for CD, DVD, and BD wavelengths, then recording/reproducing on multiple disk types is enabled, but device size and complexity increase
Solution Approach 1:
The patent merges multiple optical systems into a unified structure by sharing common components such as the beam splitter, light receiving element, and reflective plate. The CD/DVD objective lens and BD objective lens are integrated into a single optical path configuration, allowing one optical pickup device to handle multiple disk types without requiring completely separate systems for each wavelength.
Solution Approach 2:
The optical pickup device is designed with universal components that can handle multiple wavelengths. The beam splitter, light receiving element, and reflective plate serve multiple functions across CD, DVD, and BD operations. The objective lens system is configured to accommodate both CD/DVD wavelengths and BD wavelength, enabling a single device to perform recording and reproducing on various optical disk types.
2Adaptability or versatility
If separate optical systems are used for CD, DVD, and BD wavelengths, then recording/reproducing on multiple disk types is enabled, but device volume increases
Solution Approach 1:
The patent merges multiple optical systems into a unified structure by sharing common components such as the beam splitter, light receiving element, and reflective plate. The CD/DVD objective lens and BD objective lens are integrated into a single optical path configuration, allowing one optical pickup device to handle multiple disk types without requiring completely separate systems for each wavelength.
Solution Approach 2:
The optical system employs a nested arrangement where the BD objective lens and CD/DVD objective lens are positioned within a shared optical path. The beam splitter, light receiving element, and reflective plate are arranged in a nested configuration that allows multiple optical functions to coexist in a compact volume, with components strategically positioned to minimize space requirements while maintaining optical performance.
3Volume of moving object
If a shared optical system is used for CD/DVD and BD, then device size is reduced, but light receiving detection accuracy may deteriorate
Solution Approach 1:
The patent applies local quality by optimizing the reflective plate's characteristics specifically for BD wavelength while maintaining its functionality for CD/DVD wavelengths. The reflective plate is positioned and designed to reflect BD light with high efficiency to the light receiving element, ensuring that detection accuracy for BD is not compromised despite the shared optical path. The beam splitter and other components are also locally optimized to maintain performance across different wavelengths.
Solution Approach 2:
The reflective plate serves as an intermediary component that mediates between the BD objective lens and the light receiving element. It is strategically positioned to ensure that BD return light is efficiently reflected to the light receiving element while CD/DVD light paths are appropriately managed by the beam splitter. This intermediary arrangement ensures that detection accuracy is maintained for all disk types despite the shared optical system.
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 efficient recording and reproducing on multiple disk types within a compact space, maintaining light receiving detection accuracy and reducing noise interference, thus facilitating miniaturization and thinning of optical disk devices.
Implementation Method 1
a dichroic mirror, that is provided between the first light source and the first objective lens, for regularly reflecting a part of the first light, transmitting a part of the first light and transmitting return light of the second light
Implementation Method 2
The dichroic mirror is formed so that a product of reflectance of the outward light of the first light and transmittance of return light of the first light becomes 20% or more to 25% or less regardless of a polarization direction of light incident on dichroic mirror
Implementation Method 3
a first objective lens for focusing the first light and emitting the first light to the optical disk, a second objective lens for focusing the second light and emitting the second light to the optical disk
Implementation Method 4
a first light source for emitting first light as linear polarized light, a second light source for emitting second light as linear polarized light
Data Source
AI summary
An optical pickup device has a DVD/CD laser diode for emitting a DVD/CD laser beam as linear polarized light, and a BD laser diode for emitting a BD laser beam. The optical pickup device has a dichroic mirror that regularly reflects a part of the DVD/CD laser beam, transmits a part of the DVD/CD laser beam, and transmits return light of the BD laser beam. The dichroic mirror is formed so that a product of reflectance of outward light of the DVD/CD laser beam and transmittance of return light of the DVD/CD laser beam becomes 20% or more to 25% or less. A light receiving element receives the return light of the DVD/CD laser beam transmitted through the dichroic mirror or the return light of the BD laser beam transmitted through the dichroic mirror.