# U.S. Patent 1,773,980 — Farnsworth, "Television System"

**Type:** source
**Status:** Useful
**Confidence:** High
**Source Type:** patent
**Publisher:** U.S. Patent and Trademark Office
**Retrieved:** 2026-08-12
**URL:** https://image-ppubs.uspto.gov/dirsearch-public/print/downloadPdf/1773980
**Updated:** 2026-08-11

## Summary

Philo T. Farnsworth's foundational television patent — the one whose January 7, 1927 filing date fixes his priority over RCA. It claims a method and apparatus for transmitting a moving image electrically, with no mechanically moving parts at either end, by forming an "electrical image" on a photosensitive plate and sweeping that image across a small aperture.

This is the document behind the date the wiki repeats. It is the dated instrument itself, not an account of it.

## Useful Claims

- Patent number 1,773,980, titled "Television System". Application serial no. 159,540, filed January 7, 1927; granted August 26, 1930.
- The grant heading reads "Philo T. Farnsworth, of Berkeley, California, assignor by mesne assignments, to Television Laboratories, Inc., of San Francisco, California". The specification is signed at San Francisco on December 21, 1926 — the disclosure was written seventeen days before the filing date the priority fight later turned on.
- The specification states the object of the invention as television "in which the conversion and dissecting of the light shades of the object to be transmitted, to electricity and the reconversion of such electricity to form an image is accomplished … without the necessity of employing any mechanically moving parts." All-electronic scanning is claimed on the face of the patent, not inferred from later accounts.
- The camera tube described is the image dissector in its original form: light from the whole scene is focused at once onto a flat mesh cathode coated with "a light sensitive material such as sodium, potassium, or rubidium", producing an electron discharge whose cross-section carries the light pattern. The patent names that discharge "an electrical image".
- Scanning is done by moving the electrical image, not a beam over a target: two pairs of deflecting plates driven at different frequencies sweep the image past "an electric shutter … in which there is a small aperture", and the current through the aperture is the picture signal. Claim 15 covers "means for forming an electrical image, and means for scanning each elementary area of the electrical image".
- The same patent covers the receiving side, using a polarizing prism and a light rotator driven by the picture signal so that the reproduced beam also has no mechanical scanner.
- Farnsworth filed two further applications on November 7, 1927 that reference this one — serial 231,690 (issued as 1,758,359) and serial 231,691 (issued as 1,773,981).

## Reliability Notes

Primary tier. A granted U.S. patent is a dated public instrument the USPTO is obliged to keep; the number is the permanent retrieval key and no archive snapshot is needed. The `image-ppubs.uspto.gov` URL is the issuing body's own PDF of the grant.

What this document does and does not settle. It settles the filing date, the grant date, the inventor and assignee of record, and the technical content of the disclosure. It does not settle the September 7, 1927 first-transmission date, the 1922 Tolman chalkboard sketch, the 1935 interference ruling, or the 1939 RCA license — none of those are in this document, and the fact page cites them elsewhere.

The full specification text used for the claims above was read from an OCR transcription of the grant. Machine reading of 1930 letterpress is imperfect — reference numerals in particular come through inconsistently — so the quotations above are limited to passages legible without reconstruction, and the inventor's name in the grant heading is paraphrased rather than transcribed character-for-character.

## Related Pages

- [Philo Farnsworth and Electronic Television](philo-farnsworth-television.md)