Optical Phonograph Playback via Angular Light Encoding
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Solution Overview
Problem
Existing optical playback systems for analog phonographic records are complex, sensitive to surface irregularities, and limited in measuring groove border position, leading to errors in sound signal extraction due to their reliance on curve measurement and optical resolution limitations.
Innovation Solution
A device that generates a light beam with a varying spectrum based on its incident angle, using a trichromatic filter and condenser to encode light colors or intensity, allowing for accurate measurement of groove wall angles and radial movement speed through image processing, eliminating the need for complex tracking and improving digitization accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional electro-mechanical phono cartridges are used for playback, then mechanical engraving can be utilized, but the method is aggressive and damages the record surface
Solution Approach 1:
The patent replaces the mechanical needle-cartridge system with an optical system that uses light beams to read groove information without physical contact. The optical unit projects light onto the record groove and detects reflected light patterns to extract audio signals, eliminating mechanical wear and damage to the record surface.
2Measurement precision
If optical playback systems measure groove border position, then sound signal can be extracted, but measurement accuracy is limited by optical resolution and curve measurement errors
Solution Approach 1:
The patent uses a colored filter with angularly varying transmission characteristics to encode light colors or intensity based on the incident angle. As the light beam reflects off different sections of the groove wall at different angles, the filter transforms these angle variations into color or intensity variations that can be detected by the image sensor, thereby measuring groove wall angles with precision beyond standard optical resolution limits.
Solution Approach 2:
The patent changes the measurement parameter from groove border position (curve measurement) to groove wall angle. By measuring the angle of the groove wall relative to the radial direction through optical intensity variations, the system achieves more accurate sound signal extraction, particularly in the middle depth area of the groove where more information is contained.
3Ease of operation
If complex tracking systems are used to follow the groove, then playback can be maintained, but device complexity increases
Solution Approach 1:
The patent employs an image sensor that captures the entire light pattern reflected from the groove section illuminated by the beam. The system processes this image to automatically determine groove position and orientation without requiring mechanical tracking components to physically follow the groove. This self-service approach simplifies the device by eliminating complex tracking mechanisms.
4Productivity
If multiple handling and complex equipment are used for digitization, then sound archives can be processed, but productivity decreases for serial digitization of large collections
Solution Approach 1:
The patent extracts only the essential function needed for playback and digitization: projecting light onto the groove and detecting reflected light patterns. By removing unnecessary mechanical components, tracking mechanisms, and complex handling systems, the device achieves a streamlined configuration that enables rapid serial processing of sound archives while maintaining accurate sound signal extraction.
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 solution enhances the accuracy of sound signal extraction by measuring groove wall angles and radial movement speed, reducing errors caused by surface irregularities and improving digitization quality, especially in fragmented records, while simplifying the equipment and handling process.
Implementation Method 1
an optical unit that includes an optical source that forms an initial descending light beam so that it forms a light mark on the first wall and a beam reflected by the wall forming a light mark reflected at a mark position that is proportional to the recorded signal
Implementation Method 2
a colored filter with a color variation in a direction that is perpendicular to the optical axis of the incident beam and parallel to the record plane
Data Source
AI summary
This invention relates to equipment for the optical playback of sound media which includes resources (1) that has engraves grooves, (3, 9) for generating at least one light beam that presents a light spectrum variation according to its incidence angle on an area of the sound media and an image sensor (7) placed so that it recovers the light reflected by said area of the sound media.