An aperture grille is one of two major technologies used to manufacture color 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...

 (CRT) television

Television

Television is a telecommunication medium for transmitting and receiving moving images that can be monochrome or colored, with accompanying sound...

s and computer display

Computer display

A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...

s; the other is shadow mask

Shadow mask

The shadow mask is one of two major technologies used to manufacture cathode ray tube televisions and computer displays that produce color images. The other approach is aperture grille, better known by its trade name, Trinitron. All early color televisions and the majority of CRT computer monitors...

.

Fine vertical wires behind the front glass of the display screen separate the different colors of phosphor

Phosphor

A phosphor, most generally, is a substance that exhibits the phenomenon of luminescence. Somewhat confusingly, this includes both phosphorescent materials, which show a slow decay in brightness , and fluorescent materials, where the emission decay takes place over tens of nanoseconds...

s into strips. These wires are positioned such that an electron beam from one of three guns at the rear of the tube is only able to strike phosphors of the appropriate color. That is, the blue electron gun will strike blue phosphors, but will find a wire blocks the path to red and green phosphors.

The fine wires allow for a finer dot pitch as they can be spaced much closer together than the perforations of a shadow mask, and there need be no gap between adjacent horizontal pixels.

During the display of bright images, a shadow mask warms, and expand outward in all directions (sometimes called blooming). Aperture grilles do not exhibit this behavior; when the wires heat up, they expand vertically. Because there are no defined holes, this expansion does not affect the image, and the wires do not move horizontally.

The vertical wires of the aperture grille have a resonant frequency and will vibrate in sympathetic resonance

Acoustic resonance

Acoustic resonance is the tendency of an acoustic system to absorb more energy when it is forced or driven at a frequency that matches one of its own natural frequencies of vibration than it does at other frequencies....

 with loud sounds near the display, resulting in fluttering and shimmering of colors on the display. To reduce these resonant effects, one or two horizontal stabilizing wires, called "damping wires", are welded across the grille wires, and may be visible as fine dark lines across the face of the screen. These stabilizing wires provide the easiest way to distinguish aperture grille and shadow mask displays at a glance. The stabilized grille can still vibrate but the sounds need to be loud and close to the display.

Additionally, aperture grille displays tend to be vertically flat

Flatness

Flatness may refer to:*Flatness *Flatness *Flatness *Flatness *Flatness , a geometrical tolerance required in certain manufacturing situations*Flatness...

 and are often horizontally flat as well, while shadow mask displays usually have a spherical curvature

Curvature

In mathematics, curvature refers to any of a number of loosely related concepts in different areas of geometry. Intuitively, curvature is the amount by which a geometric object deviates from being flat, or straight in the case of a line, but this is defined in different ways depending on the context...

.

The first patent

Patent

A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

ed aperture grille televisions were manufactured by Sony

Sony

, commonly referred to as Sony, is a Japanese multinational conglomerate corporation headquartered in Minato, Tokyo, Japan and the world's fifth largest media conglomerate measured by revenues....

 in the late 1960s under the Trinitron

Trinitron

Trinitron is Sony's brand name for its line of aperture grille based CRTs used in television sets and computer display monitors. One of the first truly new television systems to enter the market since the 1950s, the Trinitron was announced in 1966 to wide acclaim for its bright images, about 25%...

 brand name, which the company carried over to its line of CRT computer monitors. Subsequent designs, either licensed from Sony or manufactured after the patent's expiration, tend to use the -tron suffix, such as Mitsubishi

Mitsubishi

The Mitsubishi Group , Mitsubishi Group of Companies, or Mitsubishi Companies is a Japanese multinational conglomerate company that consists of a range of autonomous businesses which share the Mitsubishi brand, trademark and legacy...

's DiamondTron and ViewSonic

ViewSonic

ViewSonic Corporation is a manufacturer and provider of visual technology, specifically CRT monitors, liquid crystal displays, projectors, plasma displays, HDTV technology, and mobile products, including Mini and All-in-One PCs and wireless monitors....

's SonicTron.

Cromaclear

Cromaclear

Cromaclear is a CRT technology pioneered by NEC during the mid to late-90s. It was claimed that Cromaclear could offer the image clarity and sharpness of the Trinitron and Diamondtron aperture grille CRTs without the disadvantages e.g...

 is an improvement of the aperture grille technology, pioneered by the NEC Corporation; one of its advantage is the lack of the damping wires.

While many considered aperture grille technology to produce superior images, advances in shadow mask and hybrid technologies since the 1990s have made people's preferences more a matter of personal choice or specific application. Furthermore, the arrival of inexpensive liquid crystal display

Liquid crystal display

A liquid crystal display is a flat panel display, electronic visual display, or video display that uses the light modulating properties of liquid crystals . LCs do not emit light directly....

 (LCD) monitors and other flat-screen designs has, for many applications, rendered CRTs obsolete.

See also

• Cromaclear
  Cromaclear
  Cromaclear is a CRT technology pioneered by NEC during the mid to late-90s. It was claimed that Cromaclear could offer the image clarity and sharpness of the Trinitron and Diamondtron aperture grille CRTs without the disadvantages e.g...
  
  
• Shadow mask
  Shadow mask
  The shadow mask is one of two major technologies used to manufacture cathode ray tube televisions and computer displays that produce color images. The other approach is aperture grille, better known by its trade name, Trinitron. All early color televisions and the majority of CRT computer monitors...
  
  
• Trinitron
  Trinitron
  Trinitron is Sony's brand name for its line of aperture grille based CRTs used in television sets and computer display monitors. One of the first truly new television systems to enter the market since the 1950s, the Trinitron was announced in 1966 to wide acclaim for its bright images, about 25%...
  
  
• Chromatron
  Chromatron
  The Chromatron is a color television cathode ray tube design invented by Nobel prize-winner Ernest Lawrence and developed commercially by Sony, Litton Industries and others. The Chromatron offered brighter images than conventional color television systems using a shadow mask, but a host of...