How Does a Teleprompter Work?
Teleprompters have become some of the most essential parts of modern television production and speech-giving. Many of today's presenters would prefer to appear on camera completely naked than to go without their teleprompter. The fact is, however, that despite its widespread use and rabid popularity, the teleprompter is essentially a quite simple machine.
At its base, skeleton level, every teleprompter consists of a regular computer, complete with its monitor, and a pane of beamsplitter glass. This highly technical glass must be produced in a vacuum chamber and is significantly different than ordinary pane glass. In fact, it's so specialized that there are only a few companies in the entire world that manufacture it. On a software level, a teleprompter must be accompanied by a word processor able to invert text and scroll it downward at a desired speed. Although combining these hardware pieces correctly could result in a primitive teleprompter, today's professionally manufactured teleprompters combine all sorts of additional techniques and features to make displaying and reading the text as effortless a process as possible.
The display monitor must be laid on its back so that the screen is facing directly upward. The text to be displayed and scrolled will be projected onto a mirror, therefore, since mirrors reverse the objects displayed on them, the text must first be inverted on the screen.
The pane of beamsplitter glass must be turned into a one-way mirror that will allow the text projected onto it to be seen from one side and remain invisible from the other side. This is done using a piece of dark linen to shroud one side of the glass, the side facing the camera, so that the light from that side passes through it instead of reflecting back. The other side of the glass, the side facing the presenter, will take on the appearance of a mirror and reflect the text from the monitor straight into the eyes of the presenter, reversing it in the process so that it becomes readable to him or her.
The teleprompter software used to compose and display the text is another essential piece of the puzzle. The speed of playback must be able to be very specifically controlled, either by setting a specific pace ahead of time or by a live human being, scrolling the text in real time at the desired rate. Today's teleprompter software often makes use of extremely high contrast text and backgrounds to make the words as readable as possible for the presenter. Other features may include selectable cue points, a wireless remote control, multiple text input methods, and intelligent screen resolution management.