Understanding LCD Panels, TFT Viewers, and Trinitron Screens
LCD Panel Driver Functions
The functions associated with an LCD panel driver include:
- Generation of polarization
- Driving voltages
- Addressing of the array
TFT Viewer and MOS Transistors
In a TFT (Thin-Film Transistor) viewer, MOS transistors are placed behind the liquid crystal, associated with a capacitor, forming a new layer in a matrix.
Electromagnetic Deflection Principle
Electromagnetic deflection involves electrodes that move an electron beam to sweep across the screen. These devices are mounted on a yoke near the funnel of the glass tube. Precise adjustment during manufacturing is crucial.
If the deflection system is moved from its optimal position, it can cause:
- Alterations in color purity
- Geometry scanning issues
- Convergence problems of beams on luminescent areas of the tube
The picture tube is scanned from top to bottom and left to right, requiring two deflection systems: one vertical and one horizontal. The electron jet is governed electromagnetically by generating magnetic fields that influence the electrons’ path to the screen. These magnetic fields are created by coils located in the deflection yoke, with two coils in the vertical plane to control beam movements. Applying current to the vertical deflection coils creates a horizontal magnetic field. Fixed magnets are also placed to correct convergence issues.
Trinitron Cannon Composition and Functioning
The basic principle is similar to other tubes, but with notable technical differences:
Electrostatic Cannon
The electron gun uses a triple configuration, managing three electron beams with a single group of control electrodes. A key difference is the inclusion of static output convergence plates to change the path of the beams, ensuring they coincide at the point of intersection for effective convergence.
Aperture Grille
The Trinitron tube replaces the perforated mask with a vertical grid, formed by hundreds of slits that scroll across the screen. The crossing of the three electron beams occurs in the gaps of the grid, providing bounded margins of beams in the horizontal plane but not in the vertical.
Screen
The most obvious difference is the flat screen in the vertical sense. This creates a cylindrical image curved only horizontally. Permanent magnets, called permalloy, are used on the rear cone of the tube to adjust convergence.
Differences Between PIL and Trinitron Screens
The autoconvergent PIL model features a gun in a horizontal line with two settings:
Color Purity
A set of rings and magnets rotate around the neck of the tube. The outer rings adjust the path followed by the electron beams, ensuring each beam affects its intended color.
Static Convergence
Magnets act on the beams, separating them to display three independent RGB grids, or converging them to form a single white image when correctly aligned.
The Trinitron tube has a flat screen in the vertical sense, creating a cylindrical image curved only horizontally. Permanent magnets, called permalloy, are used on the back of the cone tube to adjust convergence.