How Does a Video Camera Tube Work?

A video camera tube, also known as a cathode ray tube (CRT), is an essential component of analog television cameras. It was invented in the early 20th century and was widely used until the advent of digital cameras. In this article, we will explore the inner workings of a video camera tube and understand how it captures images.

What is a Video Camera Tube?

A video camera tube is a vacuum-sealed glass container that contains an electron gun, a fluorescent screen, and an aperture. The electron gun emits a beam of electrons that are focused onto the fluorescent screen by an electromagnetic field. When the electrons hit the fluorescent screen, they cause it to emit visible light, which creates an image.

Types of Video Camera Tubes

There are three types of video camera tubes:

  • Iconoscope: The first type of video camera tube invented in 1923 by Vladimir Zworykin.
  • Image Orthicon: Invented in 1940 by Albert Rose and Ernst Weber.
  • Vidicon: Invented in 1951 by RCA.

Each type has its unique design and way of functioning.

The Working Principle

The working principle of a video camera tube can be explained in four stages:

Stage 1: Scanning

The first stage in capturing an image is scanning. The electron gun emits a beam of electrons that scans across the fluorescent screen horizontally from left to right. This process is called horizontal scanning.

Stage 2: Horizontal Blanking

During this stage, the electron beam is turned off while it returns to its starting point on the left side of the screen. This process is called horizontal blanking.

Stage 3: Vertical Scanning

Once the electron beam reaches the left of the screen, it moves down a little bit and starts scanning again, but this time vertically. This process is called vertical scanning.

Stage 4: Vertical Blanking

Similar to horizontal blanking, vertical blanking occurs when the electron beam turns off while returning to its starting point at the top of the screen.

Advantages and Disadvantages

Although video camera tubes were widely used in the past, they have several disadvantages. For instance, they are bulky and heavy, making them difficult to carry around. Additionally, they require a lot of power to operate and generate heat.

However, one advantage of video camera tubes is that they can capture high-quality images with excellent color depth and contrast ratios. They are also capable of capturing fast-moving objects without any blurring or distortion.

The Future of Video Camera Tubes

With advancements in digital technology, video camera tubes are becoming increasingly obsolete. Digital cameras offer superior image quality and are much more compact than their analog counterparts. However, some industries still use analog cameras for specific applications like surveillance systems.

In conclusion, a video camera tube is an essential component in analog television cameras that captures images by emitting a beam of electrons onto a fluorescent screen. Although they have several disadvantages compared to digital cameras, they were once the primary means of capturing moving images for television broadcasts.