Les tables publicitaires brevetées par Plessner aux Etats-Unis -1875)
Histoire de la télévision - Articles, biographies, vidéos, documents, agenda, ressources, bibliographie
"Der Fernseher (Telelekstroskop)",
Wien, Mittwoch 9 März 1898, n°1466, p.5.
Nous publions ici une traduction en anglais d'un des articles parus à Vienne dans les premiers mois 1898 rapportant la démonstration, apparemment réussie, d'une transmission d'images à distance recourant au Fernseher (Telelekstroskop) pour lequel Jan Szczepannik et Ludwig Kleiberg avait obtenu du Patent Office un brevet le 24 février de la même année.
Pour traduire le mot "Fernseher", qui désigne toujours aujourd'hui en allemand le récepteur de télévision, on a ici utilisé le terme "Televisor" que Baird utilisera dans les années 30.
L'article occupe une pleine page, avec quasi deux tiers de la page occupés par la reproduction de quatre des figures du brevet. Les mentions d'exclusivité et d'interdiction de reproduction qui figurent en haut de l'article laissent penser qu'il s'agit bien de la première présentation publique de l'appareil. Le neuvième paragraphe mentionne cependant un article précédent, qui était probablement moins détaillé dans la description technique.
Les premiers paragraphes reprennent, de manière plus succinte, la description du Fernseher tel qu'on la connaissait déjà à partir du brevet. L'intérêt de l'article réside surtout dans les paragraphes suivants. On y apprend :
1. Que Szczepanik pense déjà à perfectionner son appareil en vue de sa démonstration à l'Exposition universelle de Paris (1900).
2. Que c'est Ludwig Kleinberg, l'associé de Szczepanik, qui partage avec lui le bénéfice du brevet et qui, en tant que banquier est probablement son sponsor, qui pense aux applications pratiques de l'appareil, et en particulier la possibilité de l'utiliser pour le divertissement des foules, mais aussi pour des utilisations similaires à celles du télégraphe et du téléphone, y compris des applications militaires.
3. L'article nous surtout que l'appareil a été construit par l'architecte Habrich et qu'il a fonctionné avec succès. Il y a malheureusement peu de précisions sur ce succès : qui étaient les "hôtes choisis", quel type d'images ont été transmises, pendant combien de temps et avec quelle qualité ?
La traduction de l'allemand vers l'anglais est due à Nils Klevjer Aas
The Televisor (Telelektroskop)
(Exclusive to the Reichswehr) (Reproduction prohibited)
Facta, non verba!
The above outline shows the design of the electrical television, which has been invented by Jan Szczepanik. We are thankful for the use of this drawing to the technician’s patron, Mr Ludwig Kleinberg of Vienna.
Anyone who observes the drawing in connection with the short text that we are publishing on it, will reach the conclusion, which we have also reached, that it is possible to transmit optical phenomena over distance by means of the televisor.
Szczepanik’s invention is important, it is amusing and subtle.
Its particular feature is the admiration it evokes in the logical mind: 1. The principle, that a picture may be broken up into series of points for the purpose of transmission, and that these points appear in an uninterrupted stream on a screen, which has the capacity to transform the differences in light [intensity] into variations in an electrical current. 2. The ability, due to the fallible design of the human eye, of perceiving a series of rapidly following dots of light in the pattern of a figure as the figure itself.
In order to understand the televisor it is necessary to have a knowledge of the general laws of physics:
When optical impulses reaches the human eye in intervals, which are shorter than 1/10 of a second, the eye is not capable of distinguishing one impulse from the next, but will rather perceive them as one continuous impulse.
Selenium possesses the particularity that its capacity for producing electric charges is dependent on the degree to which it is illuminated.
G is the object whose picture is to be transmitted. It is placed in front of a narrow slit between the screens v and v¹ of the transmitter apparatus (A), behind which a narrow, linear mirror a is oscillating on the axis c in synchronisation with the electromagnet E, like the key of a Morse device. The light beam which falls on this mirror line from G are reflected to a second, vertically mounted line mirror a. Both mirrors are anchored to electromagnets connected to the same electrical circuit, and are oscillating synchronously. The linear picture captured by the first mirror is reproduced on the second mirror as a series of dots of light, which are reflected onto a Selenium cell (S). The Selenium illuminated in this manner changes its capacity to act as an electric conductor with the intensity and colour of the light which reaches it.
The electric current which is passing through the Selenium cell from the battery B will be changed into a series of electrical oscillations according to the variations in the light which reaches the cell. The current is transported by the wire L to the receiver device (A¹). In the receiver this current "washes across" the electromagnet E², on whose anchor a prism (p) has been mounted in such a way that it rotates on its longitudinal axis according to the changes in pull from the electromagnet and a spring. The diffuse daylight which penetrates through the aperture O² or [which is produced by] the light bulb l is split into colours by the prism. The coloured spectrum which plays through the aperture O¹ will result in changes in the colour [of the ray of light] which penetrates through the aperture O¹, according to the intensity of the movements of the electromagnet E². Thus a ray of changing colour will play upon the linear mirror in the receiver station through the aperture O¹, all according to the changing position of the rotating prism. The receiver is designed in the same manner as the recording station and will, due to the effect of the electromagnets E and E¹ (fed by the batteries B and B¹) oscillate synchronously with the recording station. The ray of light which thus emanates from the prism and is reflected by these mirrors arrives through the aperture between the screens v and v¹ to the eye of the beholder, or onto the opaque screen G¹. The light dots arrive in intervals of less than 1/10 of a second. As the eye is not able to separate impulses which arrive so close to one another, the perception of these dots of light is (like with the stroboscope) of a complete picture. If the object is moving, then the physiological processes in the eye of the observer are identical to those caused by watching the cinematograph.
Through the appropriate use of lenses in front of the aperture in A one is able to record pictures of a considerable size, even – as we claimed in our first article – pictures of manoeuvres, and to project and photograph those as virtual pictures with the aid of lens systems in front of A¹.
One should not assume that Szczepanik’s invention is totally rid of shortcomings. One failing, due to the fact that one had to lay three very expensive wires, has already been overcome. During the screening at the Paris Exhibition in 1900 only one wire will be required. One [more] shortcoming is the flickering movement of the picture, as is also seen in the cinematograph: a third one is that the colours, in which the pictures can be seen, are not quite clear. One should, however, keep in mind that such shortcomings are mere trifles when compared with the immensity of the undertaking and the elegance of the solution. One believes that this idea, just like any other major idea, harbours in its grandeur the possibilities of development.
It remains to speak of the impact of the invention. It is clear that it is not up to a physicist to satisfy the desire for spectacle of the audience. Kleinberg, who has given Szczepanik’s ideas their practical shape, sees the equivalent of telegraphy and telephony in this telelektroskop. He would like to help supply the invention with the wherewithal to directly serve communication by letter.
Whatever they may be, the prophecies are encouraging. Joy should well up in us that an Austrian has solved the riddle, which thinkers of other nations have tried in vain to unravel.
The television was, before it was shown to the Central Committee of the Paris Exhibition, demonstrated to the famous architect Habrich in Hagen and invited guests. Eye witnesses have reported to us that the transmission of pictures with the aid of the televisor was totally successful. That is – facta, non verba.
Legend to the illustrations:
(Top) Front view of a mirror: c = pivoting axis, a = reflecting line, b = armature of the electromagnets.
(Bottom) Graphic illustration of the production of the picture through the sequence of spots. The zig-zag line K in fig. IV is the electroscopic image.