An introduction to the Mechanical Television Workshop

FOREWORD

The machines of my Mechanical Television Workshop are mainly experimentals devices using modern technology of electronics serving the Nipkow disc system and the Gardner mirror screw for analyzing and restoring television images. So, they doesn't pretend reflecting totaly the reality of aparatus having existed in the old times. As the others machines, the J.L. BAIRD TELEVISOR replica, although being similar to the original set, contains modern components which makes it working more efficiently than the genuine one. A need for demonstration purposes.

Video clip web site introduction by roger Dupouy.


TECHNOLOGY AND PRINCIPLES

"A television image is a lure". How can one affirm such a thing? Well, that needs some explanations. While a cinematographic camera captures wholes images and fix them on the support which will become a film after processing, the things are quite different in television. Here, the televised image (real scene or cinematographic projection) is analyzed point by point sequentially by the camera and the information relative to an image element is transmitted immediately to one or more receivers. So television can be defined as a real time image processing system.

So, what about the tape or DVD video recorders/players? Well, in fact such devices generates signals similar to those of a television camera. So, the TV receiver which is connected to them (sometime build in the same box), must always reformat the image, based on the information it receives. Consequently, we can say the following:

A television image is essentialy ephimerous, because it disappears as soon as created. To be more precise, let us say that a television image is nothing more than the fugitive trace of a unique luminous information, corresponding to an image element (i:e pixel), which moves very quickly in front of our eyes at the surface of a screen (cathodic, plasma or LCD) or through the holes of a scanning disc. The luminous traces sweeping the screen forms the lines and the succession of the lines makes the image structure. Thanks to our physiological faculty called 'retinal persistency', which makes it possible for our brain to keep memorized a luminous information during approximately 1/10th of second, we can integrate those traces of televisual sweeping as a whole image. This particularity makes us understand thus, why the television images of the past, including those of Mechanical Television, disappeared forever.

To observe them again the very same way the early televiewers did, there is only one solution: recreate them using unique experimentals tools! That is what I tried to do in building the prototypes presented in the following pages. The group of machines and devices described here-after, are part of my so-called "Mechanical Television Workshop" by which we can see again early television images.. in real-time!