US2034162A - Picture transmission system - Google Patents

Picture transmission system Download PDF

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Publication number
US2034162A
US2034162A US457723A US45772330A US2034162A US 2034162 A US2034162 A US 2034162A US 457723 A US457723 A US 457723A US 45772330 A US45772330 A US 45772330A US 2034162 A US2034162 A US 2034162A
Authority
US
United States
Prior art keywords
message
paper
stylus
resistance
transmission system
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US457723A
Other languages
English (en)
Inventor
Tweed Cyril John Francis
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
RCA Corp
Original Assignee
RCA Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by RCA Corp filed Critical RCA Corp
Application granted granted Critical
Publication of US2034162A publication Critical patent/US2034162A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/40056—Circuits for driving or energising particular reading heads or original illumination means
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/23—Reproducing arrangements

Definitions

  • This invention relates to picture and like telegraph systems, and apparatus for use therein. More particularly, the invention relates to picture telegraph systems of the kind in which 5 the picture or other message is inscribed in conducting ink upo'n a message form from which it is picked up for transmission.
  • a message form for use in a picture or like telegraph system of the kind referred to is made of insulating material
  • the message is inscribed on the uncoated surface of the insulating material, and the ink soaks through said material forming a high or semi-high resistance path to the conducting layer at those places at which 20 inscription has been made.
  • the resistance of the path to the conducting layer will, of course, vary with circumstances, but in practice said resistance will generally lie between 1000 ohms and 2 or 3 megohms.
  • a message form consists of detail paper coated on one side with India ink or the material known as Aquadag.
  • metal coated paper such as that known as Mansbridge paper, is employed.
  • the paper employed should, of course, be sufiiciently absorbent to permit the ink with which the message is written to soak through to the conducting layer, but it should not be too absorbent otherwise a conducting coating of ink may go right through in places and give a blotchy effect.
  • the inscribed message form may be picked up and the message transmitted by means of a metal scanning stylus in the following manner, for example:
  • the form is wrapped round a metal cylinder with the conducting layer against the cylinder and scanned by a metal stylus connected through a resistance of, say, 10,000 ohms to the grid of a triode whose plate circuit is completed through a suitable output device and an anode battery to the cathode.
  • the cathode is connected through a battery to the metal cylinder and also through a bias battery and a resistance of, say, 5 megohms to the grid.
  • the various batteries and resistances are so proportioned that when the metal stylus is not in contact with an inked portion of the form i. e., where there is no marking, no plate current will flow in the valve.
  • the battery connected between the valve cathode and the cylinder applies positive potential to the grid through the marked portion, and, in consequence, plate current will flow.
  • the output will be intermittent unidirectional current, but obviously if a carrier frequency is required, an alternator or other oscillator may be conveniently interposed.
  • Mansbridge paper which is mounted coated side down on ordinary good quality writing paper which serves to give stiifness to the writing surface.
  • the mounting may be effected with ordinary paste or gum, care being taken to see that the thin tissue paper does not crinkle.
  • One edge of the Mansbridge paper is left over-lapping and this is turned over so as to provide a coated margin through which contact can be made on to the cylinder upon which the message form is placed in order that it may be picked up by the scanning stylus.
  • inks which may be employed, a solution of Aquadag of rather thick consistency so as to prevent its spreading on the somewhat absorbent paper has been found most suitable.
  • the accompanying drawing shows a suitable circuit arrangement for picking up a message from a message form in accordance with this invention.
  • This circuit arrangement has the advantage that it operates between stops, i. e., it operates in such a manner as to be substantially independent of variation in the resistance and the writing upon the message form.
  • Fig. 1 shows schematically a transmitting circuit as embodied in this invention
  • Fig. 2 illustrates one form of suitable message blank to be used in transmitting a message.
  • I is the cylinder upon which the message form is mounted and which is caused by means not shown to move in such manner that the message form thereon is explored by a stylus 2.
  • a stylus 2 In series with the cylinder and stylus is a battery 3, a resistance 4 (for example, of 5 megohms) and a bias battery 5, said resistance 4 and battery 5 being connected as shown across the grid cathode space of a thermionic valve 6.
  • An anode voltage of 100, for example, volts is applied to the anode of valve 6 through a resistance 1 of 50,000 ohms, for example, and the anode of said valve 6 is connected through two resistances 8, 9, of say 1 megohm each, to a source of negative potential, not shown, which serves as a source of grid bias potential for the following valves.
  • the junction point of the two resistances 8 and 9 is connected to the middle point of the secondary winding of a transformer I0, said secondary winding being connected to the grids of two valves ll, l2, arranged in push-pull.
  • An audio frequency is applied at the terminals l3 to the primary of the transformer l so that the valves ll, l2, are in push-pull as respects this audio frequency.
  • the plates of the valves l I, I2, are connected together through a primary of the transformer M the mid point of said primary being taken to a source of anode potential of say 150 volts.
  • the terminals 15 of the secondary of the transformer 14 serve as the output ter-' minals of the whole device.
  • This voltage is greater than the constant negative bias applied to the valves H, I2, and in consequence the grids of these valves become positive and the audio frequency note is therefore passed.
  • the direct current feeds for the valves II and I2 are carefully balanced so that key clicks are not heard in the output circuit.
  • a message form for use in picture telegraph systems and the like which comprises a partially ink absorbent material, a conducting material backed upon one side of the absorbent material, a stiffening material to which said conductive backing is secured and so arranged with respect thereto as to provide an overlapping portion, said overlapping portion being folded back to form contact with the picture telegraph system drum or the like.

Landscapes

  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • External Artificial Organs (AREA)
  • Facsimile Heads (AREA)
  • Manufacture Or Reproduction Of Printing Formes (AREA)
US457723A 1929-06-28 1930-05-31 Picture transmission system Expired - Lifetime US2034162A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB19946/29A GB335615A (en) 1929-06-28 1929-06-28 Improvements in or relating to picture and like telegraph systems and apparatus for use therein

Publications (1)

Publication Number Publication Date
US2034162A true US2034162A (en) 1936-03-17

Family

ID=10137760

Family Applications (1)

Application Number Title Priority Date Filing Date
US457723A Expired - Lifetime US2034162A (en) 1929-06-28 1930-05-31 Picture transmission system

Country Status (5)

Country Link
US (1) US2034162A (ja)
DE (1) DE556841C (ja)
FR (1) FR695940A (ja)
GB (1) GB335615A (ja)
NL (1) NL31202C (ja)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2607844A (en) * 1948-04-27 1952-08-19 Western Union Telegraph Co Wheatstone bridge having stylus shunting one arm

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
BE512710A (ja) * 1951-07-11

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2607844A (en) * 1948-04-27 1952-08-19 Western Union Telegraph Co Wheatstone bridge having stylus shunting one arm

Also Published As

Publication number Publication date
FR695940A (fr) 1930-12-23
GB335615A (en) 1930-09-29
DE556841C (de) 1932-08-15
NL31202C (ja)

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