# How James Russell Invented the Digital Optical Disc

> A 1966 invention that replaced physical needles on vinyl records with a laser beam reading digital data from a spinning disc.

- **Patent:** US 3501586
- **Original title:** Analog to digital to optical photographic recording and playback system
- **Owner:** Battelle Development Corp
- **Granted:** 1970
- **Status:** Public domain (expired)
- **Times cited:** 52
- **Field:** consumer_electronics, mechanical, telecommunications

## What it does

This patent describes a system that converts analog audio signals into digital data and encodes them onto a light-sensitive photographic disc. During playback, a light source scans the disc, and a detector converts the reflected light pulses back into an electrical signal. This process eliminates the physical contact between a needle and a record, preventing the wear and tear that degrades sound quality over time. By using digital encoding, the system ensures that the audio signal can be perfectly reconstructed without the noise or distortion inherent in analog playback.

## What it does NOT cover

- Does not cover magnetic tape recording or playback systems.
- Does not cover the specific error-correction algorithms used in later commercial CDs.
- Does not cover non-optical storage media like hard disk drives.
- Does not cover the physical manufacturing process of mass-producing consumer CDs.

## The clever bit

Russell realized that by using a light beam to read data, he could eliminate physical friction, allowing for infinite playback cycles without degrading the source material.

## Real-world examples

1. Compact Disc (CD) players
2. LaserDisc players
3. DVD and Blu-ray optical drives

## Why it matters

This technology is the direct ancestor of the Compact Disc (CD), DVD, and Blu-ray. It fundamentally shifted the music and data storage industries from analog, mechanical systems to digital, optical systems, enabling the high-fidelity audio and mass data distribution that defined the late 20th century.

## Frequently asked questions

### What does How James Russell Invented the Digital Optical Disc cover?

A 1966 invention that replaced physical needles on vinyl records with a laser beam reading digital data from a spinning disc.

### Who owns patent US 3501586?

Battelle Development Corp owns this patent, granted in 1970.

### When does this patent expire?

This patent has expired and is now in the public domain — anyone can use the invention freely.

### What is patent US 3501586 cited by?

This patent has been cited by 52 later patents that build on its ideas.

### What problem does this patent solve?

This technology is the direct ancestor of the Compact Disc (CD), DVD, and Blu-ray. It fundamentally shifted the music and data storage industries from analog, mechanical systems to digital, optical systems, enabling the high-fidelity audio and mass data distribution that defined the late 20th century.

### What does this patent NOT cover?

Does not cover magnetic tape recording or playback systems.

**Full plain-English explainer:** https://patentbrief.org/patent/us/3501586/optical-digital-recording-russell

**Original patent:** https://patents.google.com/patent/US3501586

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_Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._


## Related patents

Semantically similar inventions in the PatentBrief corpus:

- [The First Digital Camera's Core Technology](https://patentbrief.org/patent/us/4131919/digital-camera-electronic-still) — Kodak's 1978 patent on the fundamental technology for capturing, processing, and storing digital images using a CCD sensor and magnetic tape.
- [How Pulse Code Modulation Digitizes Analog Signals](https://patentbrief.org/patent/us/2266401/pcm-pulse-code-modulation-reeves) — A foundational 1938 patent describing how to convert continuous sound waves into a stream of digital numbers for transmission.
- [How Digital Audio Compression Works](https://patentbrief.org/patent/us/5579430/digital-encoding-process) — A foundational method for compressing digital audio by transforming sound into spectral data and using variable-length codes to store it efficiently.
- [How Laser Printers Use Rotating Mirrors to Write Information](https://patentbrief.org/patent/us/3867571/laser-printer-starkweather) — A 1972 Xerox patent describing how to use a spinning mirror to scan a laser beam across a page, adjusting the speed of the data to keep the image sharp.
- [How the First Laser Was Invented](https://patentbrief.org/patent/us/2929922/laser-maser) — The foundational 1960 patent by Schawlow and Townes that describes how to amplify light waves to create a laser, moving beyond microwave technology.