ApertureGrille

Aperture grille is a type of masking used in color cathode ray tube displays. It consists of a dense array of vertical metal wires or slats that are stretched across the front of the tube, positioned in front of the phosphor screen. The grille serves as the masking element that aligns with the three color phosphor stripes (red, green, and blue) so that electrons from the corresponding guns strike the intended phosphor areas.

In operation, three electron guns project electrons toward the screen. The aperture grille wires are arranged so that electrons traveling from each gun pass through the corresponding gaps and predominantly excite the matching phosphor stripes. The open area of the grille provides high light throughput, contributing to strong brightness and sharp color registration compared with some other CRT masking methods. The grille also helps maintain color purity and convergence when properly adjusted.

Aperture grille technology was most prominently used in Sony’s Trinitron and related CRT families, beginning in the late 1960s. It became a hallmark of high-contrast, bright CRT displays and was widely employed in televisions and computer monitors for several decades. The approach requires careful alignment and stabilization of the grille relative to the phosphor stripes, and it is sensitive to magnetic fields, which can affect color convergence and purity.

Today, aperture grille CRTs have largely been supplanted by flat-panel displays (LCD, LED, OLED). Nevertheless, they remain notable for their bright, vivid image characteristics and distinctive Trinitron-era image quality.