Flicker-free
Encyclopedia
Flicker-free is a term given to televisions that operate at a 100 or 120 hertz
field rate
to eliminate flicker, compared to standard televisions that operate at 50 Hz (PAL
, SÉCAM
systems
) or 60 Hz (NTSC
). Flicker-free technology is said to produce noticeably more fluid motion.
Flicker-free televisions are often labelled as being 100 or 120 Hz without using the words flicker-free in the description. Flicker-free technology is more common in countries using the 50-Hz PAL or SECAM systems, where flicker is perceived to be a more serious problem than at the 60-Hz field rate of NTSC. Flicker is far more noticeable on traditional cathode ray tube
television sets than on LCD or plasma display
s, which do not require the technology.
The technology involved in doubling the frame rate may consist simply of displaying the same broadcast image twice in rapid succession, or involve the generation of an interpolated
image between the two broadcast frames to make motion appear more natural. The issue of interlacing in traditional TV broadcasting, in which one-half of the scan lines of each frame are broadcast at a time, can be addressed with progressive scan
imaging that attempts to create a full picture from the two half images.
While flicker-free technology eliminates the problem of flicker, it can cause slight judder on fast moving images or blurring problems: fast scrolling text for example may blur.
Hertz
The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....
field rate
Field rate
The field rate of an interlaced video image is twice the effective frame rate, since interlacing draws only half of the image at a time. For example, a field rate of 60 Hertz will correspond to a 30 frames-per-second moving picture...
to eliminate flicker, compared to standard televisions that operate at 50 Hz (PAL
PAL
PAL, short for Phase Alternating Line, is an analogue television colour encoding system used in broadcast television systems in many countries. Other common analogue television systems are NTSC and SECAM. This page primarily discusses the PAL colour encoding system...
, SÉCAM
SECAM
SECAM, also written SÉCAM , is an analog color television system first used in France....
systems
Broadcast television system
Broadcast television systems are encoding or formatting standards for the transmission and reception of terrestrial television signals. There are three main analog television systems in current use around the world: NTSC, PAL, and SECAM...
) or 60 Hz (NTSC
NTSC
NTSC, named for the National Television System Committee, is the analog television system that is used in most of North America, most of South America , Burma, South Korea, Taiwan, Japan, the Philippines, and some Pacific island nations and territories .Most countries using the NTSC standard, as...
). Flicker-free technology is said to produce noticeably more fluid motion.
Flicker-free televisions are often labelled as being 100 or 120 Hz without using the words flicker-free in the description. Flicker-free technology is more common in countries using the 50-Hz PAL or SECAM systems, where flicker is perceived to be a more serious problem than at the 60-Hz field rate of NTSC. Flicker is far more noticeable on traditional cathode ray tube
Cathode ray tube
The cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen used to view images. It has a means to accelerate and deflect the electron beam onto the fluorescent screen to create the images. The image may represent electrical waveforms , pictures , radar targets and...
television sets than on LCD or plasma display
Plasma display
A plasma display panel is a type of flat panel display common to large TV displays or larger. They are called "plasma" displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent...
s, which do not require the technology.
The technology involved in doubling the frame rate may consist simply of displaying the same broadcast image twice in rapid succession, or involve the generation of an interpolated
Interpolation
In the mathematical field of numerical analysis, interpolation is a method of constructing new data points within the range of a discrete set of known data points....
image between the two broadcast frames to make motion appear more natural. The issue of interlacing in traditional TV broadcasting, in which one-half of the scan lines of each frame are broadcast at a time, can be addressed with progressive scan
Progressive scan
Progressive scanning is a way of displaying, storing, or transmitting moving images in which all the lines of each frame are drawn in sequence...
imaging that attempts to create a full picture from the two half images.
While flicker-free technology eliminates the problem of flicker, it can cause slight judder on fast moving images or blurring problems: fast scrolling text for example may blur.
External links
- Philips Natural Motion Technology, a form of interpolation.
- How television works Page on Philips website, including information on flicker-free.