Mechanical television

The so-called mechanical television is a collective term, a generic term for the first existing television method. It included the technical processes of the function of studio and transmission facilities to the beneficiaries. The later system, which replaced this first television from the 1920s to the 1940s, was the fully - electronic television, which still exists in the present.

The term mechanical television, although there is a television process that begins with

• Mechanical,
• Optical,
• Electrical and
• Electronic

Components works, have not been updated. In the field of amateur television in part, the principle of this original television is still used today.

• 2.1 transmitters
• 2.2 receiver
• 2.3 telescreen
• 2.4 Aspect ratio
• 2.5 Tuning

• 3.1 Electrical and Electronic Components
• 3.2 Optical parts
• 3.3 term assignment
• 3.4 Genuine mechanical television

• 4.1 method with components of the mechanical television
• 4.2 Continued as " electrisches television"

History

To enable TV from studios to domestic " ground glass " too many steps are necessary. The mechanical television covers the first attempts to implement this. The basis for this laid the pioneers of phototelegraphy ( historically: Kopiertelegraphie ) with their work to transfer still images. So, among other things developed in the first half of the 19th century Frederick Collier Bakewell a rotating drum covered with a sheet of metal and an electrical contact, the spiral scans an image disposed thereon. The development of this drum - principle for moving pictures was an important way of mechanical television, which was called at that time " electrisches television".

From commuting, drums and wheels

The first practical realization of the important step of the process television, the image decomposition, invented in 1883, Paul Nipkow. Previously, he presented himself three tasks:

The situation he describes as: " Apparatus, who performed such a thing, had already been in the Kopirtelegraphen; could be transferred with the help of the same a signed, under certain circumstances image into the distance, in fact. " On the way to his own invention were for him based on a turntable ( and several times later further developed ) Telectroscope from 1877 and Constantin Selencq 's d ' Shelford Bidwell and ardres 's 1881er "Tele -Photography " with a cylinder as a rotating member, the most important inventions.

Nipkow's rotating disk is named after him at the heart of his "electric telescope ". However, this is already strictly speaking, no more mechanical component, but an optical. On a real " tele-vision " but the level is not to think, because the rotating disc bildzerlegende the transmitter and the image compositing slice of the receiver are not on the same axis. A synchronization of both discs was indeed with this apparatus at a distance not yet possible, but the revolutionary thing about it was that an image converted with the help of technology into electricity through a wire " flowed " to a picture again. Under the name " electric telescope " reported Paul Nipkow in 1884 his patent at the Imperial Patent Office, which was then issued on 15 January 1885. Lack of money, however, the patent lapsed a year later and could therefore numerous television pioneers as a basis for your own developments serve.

Pioneers

The development of the " ELECTRICAL television " is based on the experiments of several technology pioneers. In particular, the work of Dénes Mihalys John Logie Baird and should be emphasized. The Scottish inventor JL Baird sat on image decomposition slice, while the Hungarian engineer D. Mihály initially a completely different method without Nipkow disk developed, in which a mirror between a horseshoe magnet oscillated rapidly. In an improved method, a mirror has been fixed to the wire strings, which have been shifted to the current passing in a rapid oscillation. After only minor successes, Dénes Mihály Nipkow disks used; The first commercial was built around 1929 in collaboration with John Logie Baird. Yet another method developed August Karolus at Telefunken, where it was working with rapidly rotating mirrors. By Karolus both systems were combined; ie the mirror wheel for the horizontal scanning and the oscillating mirror for the vertical scanning. Another pioneer of mechanical television was René Barthélemy.

John Logie Baird is one of the merit of the first fully functioning TV ( with matching camera ) to have imagined based on a Nipkow disk, in 1926. Baird's " Television Development Company " also managed the first transatlantic transmission of a television picture from London to Hartsdale (NY ) 1928.

Other pioneers of mechanical television were for France, René Barthélemy and for the United States Charles Francis Jenkins.

Establishment as a medium

Transmission facilities

A transmitter according to the principle of mechanical television, there were mainly in Europe, America and Australia. Test programs were broadcast from 1927. After the first broadcasts in 1929 was followed by regular programs in several U.S. cities, London in the UK and in Melbourne, Australia in 1931 and in Moscow in the Soviet Union. In 1932, there were at and in Berlin broadcasts among others in Paris, Brussels, Rome, and at four locations in Germany, Berlin- joke life Doberitz and king - Wusterhausen.

Receiver

With the commercialization of the mechanical television sat down for the image decomposition and for the receivers the Nipkow disk through which the image decomposition of films was used on the transmitter side until the early 1940s.

On the receiver side TV were sold with Nipkow disk until about 1935. Logie Baird drove his 1928 Model B telescreen. Since the signals on the frequency or wavelength ranges of the long, medium or short wave were transmitted considerable distances were possible, could not reach the fully electronic television today.

The equipment of the receiver was different. There were both overall receiver as well as additional receiver. The latter were, for example, the Soviet B- 2 devices, which merely gave the image again and had to be connected to a short - or medium-wave radio to receive this the image of the transmitters. The receiving of the sound could be accomplished with a second radio. The receivers were quite produce by their simple construction by amateurs themselves. Therefore enjoyed at hobbyists the devices very popular. There kits and assembly instructions have been sold almost exclusively only with Nipkow disks. Particularly successful were these homemade devices besides the UK and in the U.S., where, however, had quickly lost after a brief boom because of the many different standards and the further development of high-definition television to the mechanical television until 1933, again in importance.

The television service of the BBC broadcast in London with 30 lines until 1935. Similarly, in the Netherlands, even here in the British standard until September 1939. Virtually all recipients in both countries worked with the mechanical method. All salable receivers first generation with Nipkow disk, in the UK, France, the Netherlands, the USSR and the USA had this same image line number of a generated television image of 30 lines. Also in Germany were up to the introduction of the later standard with 180 lines ( used until 1938 ), many mechanical receiver in use, but the TV in Germany was not widespread for private people. Although there was at the sender side in the 1940s refining further developments of the mechanical image decomposition, in which again mirror - drum systems were used, making image-enhancing line numbers over 400 were possible. But to an equivalent receiver-side development was no longer in the 1940s.

Telescreen

Logie Baird marketed his television under the portmanteau " telescreen ," which was a term in common use for a television receiver even into the 1950s in the United Kingdom. This word found its way into other languages ​​, for example in Russian is as in Spanish telescreen a word for television. A distinction is made between non- mechanical or electronic image decomposition.

Aspect ratio

While also in low -definition television with mechanical Bildzerlegern mainly an aspect ratio of 1:1 or 4:3 (even when fully electronic television was considered more than 60 years at 4:3 ( 12:9 ) fixed, by all levels of quality and later color television systems until the mid- 1990s, the ratio was introduced 16:9) and horizontal lines were used, Baird used a vertical scan with images in portrait formats 3:2 and 7:3. His reasoning was that the TV anyway does not provide the necessary power for transmission of films and landscape photography, but the best for the transmission of close-ups, so usually people, was likely. The fact that the norm Baird was able to hold longer than other low -resolution systems and is still widely used even in modified form in the Narrow Bandwidth Television, speaks for the accuracy of this consideration.

Tuning

Terms

The term " mechanical television" While international practice in many countries and has established itself, though hardly come mechanical methods for application. As the only mechanical element only visible rotating Nipkow disc hole appears. Whether the term has developed due to the optical perception that this rotating element essential function was assessed as a mechanical component, is not provable. Nipkow himself described his apparatus in the patent as an " electric telescope".

Electrical and Electronic Components

The Nipkowsche device consists largely of electrically operated components, of which at least one - the selenium cell - already represents an early electronic component. Furthermore, the sound is output from the transmitter to the receiver via a cable, electrically. Even the speed of the motor which drives the Nipkow disk must be usually synchronized with an electronic circuit comprising an electron tube.

Optical parts

On the receiver side, a polarized light beam by the magnetic field of a coil in response to the signal of the transmitter selenium cell in Nipkowschen embodiment applicable rotated and filtered through subsequent lenses to the eye of the same brightness impression is generated as in the transmitter side there. This polarized light beam was measured using a special optical glass, the so-called " prism Nicolschem " is generated. Alternatively, a column filled with carbon disulphide or neon tube has been used (a " glow lamp "), for visualization of the brightness variations. A picture tube was not necessary. With the introduction of these and other optical methods television also partially already with the first optoelectronic devices, as early as 1929, the term was no longer sufficient as the mechanical television.

Term assignment

Thus it becomes clear that the concept of " mechanical television 'is too short. At the most correct would be the formation of concepts " mechanical image decomposition ". The internationally accepted term mechanical television is so rather than a historical delimiting term for all other methods of television and its technology

• From recording or sampling,
• Sound and Bildzerlegen,
• Transmitting,
• Send and receive
• To the preparation for the terminal,

Are not based on techniques from the fully electronic television.

The term is - ultimately only be understood as a generic term to distinguish. However, since the term is ambiguous and has not been updated, but as a consequence of a proper assignment of technologies developed since then often problematic.

Genuine mechanical television

Basically, a fully mechanized television is quite conceivable. The decomposition would take place in the manner described by Nipkow disk or mirror system, the transfer of the image point would there but not electrically, but done by fiber optic cable. For this purpose, a single electrical component would be necessary would be to drive eg Federnwerke or steam engines are used as the light source is natural light, candle or gas light. Several members of the Narrow Bandwidth Television Association also currently working on such a project, which is to prove that, at least in principle, television would have been possible in the 19th century.

Presence

Process with components of the mechanical television

Even today, the mechanical television is not meaningless. The Nipkow disk and mirror systems are now again used in the construction of confocal microscopes or video projectors. A particular application of the mechanical television, there was on the U.S. Pioneer spacecraft 11: As the probe is rotated around its own axis, a single photosensitive cell was attached to the outside, which scans one line by the rotation of the probe. Since the probe itself also moves, as complete images can be scanned. From the operating principle of this type of image scanning is thus quite similar to the Nipkow disk. As used Virtual Boy from Nintendo only one image line, composed of 240 LEDs; by a rotating mirror gives the impression of a complete image. As a precursor of modern billboards can be considered a process developed by Peter Schmalenbach device. Four rotating light emitting diode bar with 232 LEDs each write all 625 lines of today's television standard in the air. This creates a complete TV viewing. The machine is so, for example, the injected current TV or videos on a virtual drum kit. Nearly 122,000 pixels cause a remarkable resolution.

Continued as " electrisches television"

Projects of amateur television as NBTV.org, as seen today, the extremely narrow-band variant (English Narrow Bandwidth Television) television with a bandwidth of 2.5 kHz, for example, Baird, manufacture replicas employed in the present with the inventions, as well as complete new designs with Nipkow image decomposition slices. This will even happen, due to the significant improvement and miniaturization of components since the time of Nipkow and Baird, again and again to amazing successes. Also color image transfers, where already JL Baird experimented, are possible.

In the UK, a kit for a telescreen historical model is sold for many years.