Monochrome Picture Tube Diagram | New Topic

In this note, we are going to know about the Monochrome Picture Tube Diagram or Block Diagram. Welcome to Poly Notes Hub, a leading destination for engineering notes for diploma and degree engineering students.

Author Name: Arun Paul.

Monochrome Picture Tube Diagram

In all TV and video monitoring systems, a picture tube is used to convert video signals into variations of light.

In monochrome monitors or monochrome picture tubes, it consists of an electron gun, comprising of an indirectly heated cathode, a control grid, screen grid or accelerating anode, and a focus grid. It produces an electron beam resulting in a sharply focused spot on a fluorescent screen. A large angle deflection of the electron beam is caused by the strong magnetic field produced by saw tooth currents through horizontal and vertical deflection coils (yoke) mounted on the neck of the picture tube. There are tiny magnets for centering the beam and for eliminating the pincushion effect. It is illustrated in figure below –

Here is the monochrome picture tube diagram description and function of each parts in this monochrome picture tube block diagram –

• Cathode: The cathode is a heated element that emits electrons. It plays a crucial role in the electron gun, providing the source of electrons required for image formation.
• Heater: The heater surrounds the cathode and heats it to facilitate thermionic emission. This emission releases electrons necessary for the electron beam.
• Control Grid (G-1): The control grid modulates the intensity of the electron beam. It controls the brightness of the image by regulating electron flow.
• Screen Grid (G-2): The screen grid helps accelerate the electrons moving toward the screen. It improves beam focus and minimizes the influence of unwanted electric fields.
• Focus Grid (G-3): This component fine-tunes the electron beam, ensuring it converges to a sharp point on the screen. It helps maintain image clarity.
• Ultor (G-4): Ultor is a high-voltage anode that provides the final acceleration to the electrons. It ensures they hit the fluorescent screen with sufficient energy to produce visible light.
• Pincushion Correction Magnet: This magnet corrects geometric distortions (pincushion effect) in the display, ensuring accurate image proportions.
• Yoke: The yoke consists of deflection coils responsible for guiding the electron beam horizontally and vertically. It controls the scanning of the beam across the screen.
• Beam Centering Ring Magnet: This magnet adjusts the alignment of the electron beam to ensure it reaches the correct spot on the screen.
• Inter Aquadag Coating: The internal conductive coating, known as inter aquadag, maintains an equipotential surface inside the tube and aids in electron movement.
• External Aquadag Coating: The external coating is grounded and helps remove excess charge from the tube, preventing electrical buildup.
• Aluminum Coating: This layer assists in enhancing brightness and contrast by reflecting light emitted by the fluorescent screen back toward the viewer.
• Fluorescent Coating: When struck by the high-energy electrons, this coating emits visible light, forming the displayed image.
• Face Plane: The front part of the tube where the image is displayed. It consists of the fluorescent coating that produces the visible picture.

These are the function of each and every section or part of the monochrome picture tube diagram.