Optical Pickup Light Blocking Unit for Signal Stability
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Solution Overview
Problem
Existing optical pickup apparatuses face issues with changes in light intensity balance due to positional shifts of the light detector, leading to uncontrollable photoelectric output signals and decreased reliability, especially under temperature changes or physical impacts.
Innovation Solution
An optical pickup apparatus with a light blocking unit that partitions the light receiving portion into divided regions and blocks light beams in a predetermined range including the boundary lines between these regions, maintaining consistent light intensity across the regions even with detector displacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light detector is fixed to the housing without light blocking means, then the structure is simple, but the light intensity balance changes due to positional shifts causing uncontrollable output signals
Solution Approach 1:
The patent extracts the light blocking function from the housing structure and implements it as a separate light blocking means (such as a light blocking plate or light blocking film) positioned between the light source and light detector. This separation allows the light blocking function to be independently optimized and adjusted without complicating the overall housing structure, thereby improving signal stability while maintaining structural simplicity.
Solution Approach 2:
The light blocking means acts as an intermediary element between the light source and light detector. It mediates the light path by selectively blocking stray light and controlling the light distribution to the divided regions, ensuring stable light intensity balance even when the light detector experiences positional shifts due to temperature changes or physical impacts.
2Measurement precision
If the light receiving portion is partitioned into divided regions without light blocking means, then the tracking error detection is enabled, but the first-order diffracted light influences the detection accuracy
Solution Approach 1:
The patent extracts the harmful first-order diffracted light from the light beam reaching the light detector by positioning light blocking means in the optical path. This light blocking means is specifically designed to block the first-order diffracted light while allowing the zero-order light to reach the divided regions of the light detector, thereby eliminating the harmful influence on tracking error detection accuracy.
Solution Approach 2:
The light blocking means is strategically positioned and shaped to provide localized light blocking only in the regions where first-order diffracted light affects the divided regions of the light detector. This localized approach ensures that tracking error detection accuracy is improved without unnecessarily blocking useful light, maintaining optimal detection precision.
3Reliability
If the light detector position is adjusted for optimal signal balance, then the output signals are equal, but the position is sensitive to temperature changes and physical impacts
Solution Approach 1:
The patent implements preliminary anti-action by positioning light blocking means to preemptively counteract the effects of light detector positional shifts caused by temperature changes or physical impacts. The light blocking means is configured to maintain stable light intensity balance across the divided regions even when the light detector moves from its optimal position, thereby providing tolerance to environmental changes without requiring re-adjustment.
Solution Approach 2:
The light blocking means serves as a cushioning mechanism that compensates for positional shifts of the light detector. By strategically positioning and sizing the light blocking elements, the system creates a tolerance zone where the light intensity balance remains stable even when the light detector experiences displacement due to thermal expansion or mechanical shocks, thus cushioning against environmental variations.
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 design enhances the tolerance to detector shifts caused by ambient temperature changes or physical impacts, ensuring stable and reliable optical pickup performance by minimizing changes in output signals during motion.
Implementation Method 1
the light detector 98 for converting received light beam into an electric signal
Implementation Method 2
a polarization beam splitter 92 composed of two right angle prisms that are bonded to each other on total reflection surfaces
Implementation Method 3
a quarter-wave plate 93 formed of an optically anisotropic body, through which two mutually orthogonal polarization components of the light beam being transmitted become different in phase by a quarter of a wavelength of the light beam
Implementation Method 4
an objective lens 95 through which the light beam emitted by the lens 94 converges
Data Source
AI summary
A light blocking unit includes a plate-like member which is different from a housing member, and a light blocking portion formed on the plate-like member, for blocking light. A light detector has a light receiving portion for receiving light which is partitioned into four divided regions, by a Y-axis-wise parting line and an X-axis-wise parting line in X-Y coordinates, and outputs photoelectric output signals for the respective divided regions in accordance with intensity of the light received by the respective divided regions of the light receiving portion. Of light beams emitted from a polarization beam splitter, a part of the light beams are blocked by the light blocking unit while the other part of the light beams are not blocked and thus emitted to the light detector excluding a region defined by two sides parallel to the parting lines.