US 4,807,031 · Granted 1989-02-21

The 1989 Patent That Tried to Make TV Remote Control Invisible

Imagine hiding secret control codes inside a TV broadcast so toys and educational gadgets could respond without needing a traditional remote. This patent describes a sneaky method: modulating the brightness of TV scan lines in a pattern that a light sensor picks up, then converts those invisible signals into infrared commands that tell toys what to do.

Curated and verified by the IsItPatented Editorial team

The plain-English version

What it protects

The claim covers a method for encoding binary control data directly into video broadcast signals by subtly modulating the brightness of horizontal scan lines in alternating patterns. What's protected here is the specific technique of hiding these commands in-band (embedded within the video stream itself), having a light-sensitive device detect the modulation from the TV screen, and then transmitting the decoded data wirelessly via infrared or radio frequency to interactive devices that execute the commands. The patent also covers the apparatus — the sensor, receiver/transmitter electronics, and the cable connecting them.

Why it matters

This patent represents an early attempt to enable interactive entertainment without traditional wired remote controls. By encoding commands directly into broadcast video, it offered a way to synchronize toy and device behavior with television programming — a concept that could have created entirely new categories of interactive toys and educational products. The approach is technically innovative because it sidesteps the need for separate control channels, though it ultimately faced practical limitations in real-world implementation.

Real-world use

When watching an educational TV program, a toy sitting near your TV screen could detect hidden brightness pulses in the broadcast and automatically respond — like lighting up or playing sounds — timed perfectly to what's happening on screen.

Original USPTO abstract

Method and apparatus for in-band, video broadcasting of commands to interactive devices are described. Control data are encoded by subliminally modulating, prior to the remote, composite video broadcast of video program material, a selected sequence of video image fields. The resulting modulated video fields within the viewing area of a television, each having alternately, proportionately raised and lowered luminance horizontal scan lines, are monitored by a light sensitive device positioned adjacent the user's television screen. A semirigid, twisted pair cable connects the device to nearby receiver/transmitter electronics that discriminate the binary data from the program material and amplitude modulate a high frequency infrared (IR) carrier with the data. Interactive devices, e.g. educational aids or action toys, within range of the wireless IR transmission detect energy in this frequency range, decode the commands embedded in the control data, and selectively execute predetermined actions in response to the data-encoded broadcast. In a proposed modification, low radio frequency (RF) electromagnetic radiation emanating from the television's raster scan electronics is coupled by a conventional RF antenna to the receiver electronics, which identically discriminate the binary data, from the program material, for transmission to the interactive devices.

Patent details

Publication number: US 4,807,031
Filing date: 1987-10-20
Grant date: 1989-02-21
Assignee: Interactive Systems, Incorporated
Inventor(s): BROUGHTON; ROBERT S., LAUMEISTER; WILLIAM C.
CPC class: H04N7/163

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