Inside the Tube: A Look at Video Monitor Technology (page 2)

Tracing an Image

Now let's imagine that we put a video camera into the transparent time-slowing machine with the monitor. Let's also connect video cables from the camcorder to the monitor so that we can watch the image output from the camcorder on the monitor's screen. We aim the video camera at a still photograph. Let's throw the switch and power up the entire system.

Just as before, a dim gray dot appears at the top left corner of the screen and begins to trace a line. But inside the monitor, something interesting happens. Part of the video signal entering the monitor finds its way to the electron gun and causes the electron beam's intensity to vary wildly. On the monitor's screen, the dot flickers and flashes, leaving what looks like a string of bright and dark dots and dashes across the screen. The dot jumps back to the left side of the screen and draws another line with a similar but slightly different pattern. After several lines appear, we recognize that the monitor is drawing an image of the photograph that the video camera "sees."

Figure 3 shows the photograph's image as it appears on the monitor. One of the 483 visible lines traced by the electron beam is highlighted in white for clarity. The waveform below the photograph corresponds to the variations in the electron beam's intensity as it traces this specific…