In this blog post, we will explain the principles behind TV’s delivery of visual and auditory information, and explore the feasibility and potential of conveying other senses, such as touch and smell.
The Principles of Information Transmission in TV
Watching TV plays a significant role in modern life. In its early days, TV replaced or supplemented many aspects of radio with its ability to simultaneously convey visual and auditory information, and it expanded the scope of information delivery by creating new program formats that were impossible with radio. Although the importance of TV as hardware has diminished somewhat with the widespread adoption of the internet and smartphones, it still maintains a distinct sphere of information delivery thanks to its advantages of large screens, high resolution, and the ability to display curated, reliable information all at once. Furthermore, smart TVs are expanding the traditional TV media landscape by adding network-based functions.
Historically, TV emerged in the late 1920s and transmits information using electromagnetic waves. Traditionally, signals are transmitted in the 54–890 MHz frequency band, and these signals are classified as analog or digital depending on their generation method. While analog broadcasting was the mainstream globally in the past, many countries have undergone a digital transition; for example, South Korea switched its terrestrial broadcast transmission signals to digital as of December 31, 2012. In addition to terrestrial broadcasting using radio waves, there are also wired transmission methods such as cable, so broadcasts, channels, and services are categorized into terrestrial, cable, and other types.
The device that receives the transmitted signal and restores it to its original video and audio is commonly called a receiver. A TV receiver consists of electronic circuits that restore the signal, a tuner that allows the user to select channels, a display device that shows the video, and speakers that produce sound. Since the size, display quality, and viewing experience of a device vary significantly depending on the type of display, they are classified as cathode ray tubes (CRTs), LCDs, or LEDs.
A cathode ray tube (CRT) is a classic display that generates images by emitting electrons and causing them to strike a fluorescent screen. After emitting electrons, the path of the electron beam is bent by a magnetic or electric field so that it strikes the phosphor material at a specific location, causing that area to emit light. CRTs are physically thick because they require space for the electrons to travel, but this structure has been replaced by thin displays such as LCDs, plasma, and LEDs.
The principle behind LCDs relies on the alignment properties of liquid crystal molecules and the use of polarizing filters. Light from the backlight passes through a polarizing filter, allowing only light with a specific polarization direction to pass through. If the liquid crystal molecules are twisted between the polarizing filters, the polarization direction of the light rotates and passes through the next filter; however, when a voltage is applied to align the liquid crystal molecules, the polarization does not rotate, and the light is blocked. By adjusting the voltage to control the amount of light passing through each pixel, an image is displayed.
Audio signals are reconstructed in an electrical circuit and transmitted through speakers. The amplitude of the signal current corresponds to the loudness of the sound, the shape of the current waveform affects the timbre (sound quality), and the frequency determines the pitch of the sound. While visual and auditory signals are processed through different physical mechanisms, they share the common feature of being capable of relatively long-distance transmission via electromagnetic waves or sound waves.
Advances in display and audio technologies have enabled TVs to provide curated information through large screens, high resolution, and superior sound quality, which is why TV remains an important medium even today, despite the widespread adoption of the internet and smartphones.
New Potential for TV Development: Tactile and Olfactory Transmission
Future innovation lies not merely in improving visual and auditory information. Just as when TV replaced radio, major inflection points occur when a medium embraces entirely new sensory realms. While smell and touch (and taste) remain relatively unexplored in current media, the technologies with the highest practical feasibility are those for transmitting smell and touch.
In fact, comprehensive sensory delivery, including smell and touch, is already being implemented in some movie theaters. 4D theaters leverage the advantage of an enclosed space to provide tactile information—such as scents or vibrations tailored to the scene—in addition to high-quality sound and 3D imagery. Given that the home TV environment shares similarities with a movie theater, TVs have a relative advantage in adopting olfactory and tactile delivery technologies. When combined with well-equipped large speakers, soundproofing, and a wide screen, it is possible to recreate a scaled-down version of the movie theater experience.
In particular, haptic information can be implemented relatively easily not through the TV set itself, but via sofas or mats linked to the TV, or external devices (e.g., vibrating chairs, electronic pads). By integrating this hardware, vibrations or pressure changes tailored to the on-screen situation can be delivered, thereby enhancing immersion.
On the other hand, smell presents more technical challenges. While sight and sound can be transmitted over long distances via waves—electromagnetic waves and sound waves, respectively—olfactory signals require receptors to directly detect the molecules (particles) that produce the scent. In other words, since scent information is transmitted via physical “molecules,” it is nearly impossible to send it over a network like radio waves. Consequently, to simultaneously deliver scents to TVs in public spaces or homes, it would be necessary to install physical infrastructure (e.g., a system for transporting scents, similar to plumbing) nationwide, or to place scent-generating and storage devices in each household and periodically replace the supplies.
A realistic alternative would be to connect small, replaceable cartridge-based olfactory modules to TVs or peripheral devices. This method reproduces various scents by replacing consumables—much like printer ink cartridges—that contain specific scents. However, the cartridge method faces challenges that need to be addressed, such as maintenance, hygiene, cost, and issues related to lingering scents and mixing (where multiple scents remain and blend together). Furthermore, even if “odor data” is transmitted over a network, physical distribution and equipment deployment are essential because the hardware in each home must ultimately release actual molecules.
As such, introducing tactile and olfactory sensations to TVs involves multiple challenges of varying difficulty from both technological and infrastructural perspectives. While tactile feedback can spread relatively quickly through connected hardware, olfactory feedback requires more careful consideration in terms of distribution and management due to its reliance on physical delivery methods.
In conclusion, just as when it first appeared, television has maintained its position as a major medium based on its ability to provide high-quality visual and auditory information. While improvements in display and audio technology will continue, true innovation will come when new sensory information, such as touch and smell, is integrated. However, the methods for achieving this will vary significantly depending on the physical characteristics of each sense, and we must not forget that smell, in particular, requires solving the problem of material delivery at the molecular level.
