Analysis of information sources in references of the Wikipedia article "도트 매트릭스 프린터" in Korean language version.
[…] A well-known machine representative of the dot-matrix type of teletypewriter was the "Hell" (name of designer) teletypewriter, developed about 1930 and used prior to and during the Second World War by the German Army.
The "Hell" printer was extremely simple and reliable. Because of the narrow bandwidth requirements, it was capable of transmitting and receiving legible characters over telephony circuits considered unusable for voice transmissions because of the high noise level. However, a serious disadvantage of the machine was that it required synchronous transmission. With this type of transmission, transmitting and receiving machines operated in step and continuously. The operator had to touch the keys at the proper moment, and every lost time unit caused a space in the received print.
The PKT printer, developed in 1954–1956, was an outgrowth of the "Hell" printer. The PKT printer continued the use of electromechanical means of coding, decoding, and printing the characters on a tape or a page of paper, but did away with the need for synchronous transmission; using instead a start-stop method. While the start-stop method does require higher quality transmission links than synchronous method, since a noise pulse could be taken for a start pulse, the advantages far outweight the slight increase in bandwidth required.
While the PKT printer was considerable smaller and lighter than the "Hell" printer, the majority of the space and weight were devoted to mechanical apparatus necessary for operation. […]
[…] 1) Patent 8101 Klasse 21a1, Gruppe 17, Anmeldetag: 29.7.1952, Fernschreiber [Teletypewriter]; 2) Patent 15749 Klasse 21a1, Gruppe 7/01, Anmeldetag: 29.7.1952, Umschalteinrichtung für Fernschreiber, bei dem die Schriftzeichen in Rasterpunkte zerlegt sind [Coding equipment for a Teletypewriter at which characters are consisting of dots (RASTER - points)]; 3) Patent 15759 Klasse 21a1, Anmeldetag: 29.7.1952, Schreibkopf für Raster-Fernschreibmaschine [Recording head for Matrix type (RASTER) Teletypewriter]; 4) Patent 9043 Klasse 21a1, Anmeldetag 17.1.1953, Fernschreiber [Teletypewriter]; 5) Patent 12196 Klasse 21a1, Anmeldetag 24.6.1954, Schreibkopf für Fernschreibmaschine [Recorder for Teletypewriter] […](8 pages)
[…] A well-known machine representative of the dot-matrix type of teletypewriter was the "Hell" (name of designer) teletypewriter, developed about 1930 and used prior to and during the Second World War by the German Army.
The "Hell" printer was extremely simple and reliable. Because of the narrow bandwidth requirements, it was capable of transmitting and receiving legible characters over telephony circuits considered unusable for voice transmissions because of the high noise level. However, a serious disadvantage of the machine was that it required synchronous transmission. With this type of transmission, transmitting and receiving machines operated in step and continuously. The operator had to touch the keys at the proper moment, and every lost time unit caused a space in the received print.
The PKT printer, developed in 1954–1956, was an outgrowth of the "Hell" printer. The PKT printer continued the use of electromechanical means of coding, decoding, and printing the characters on a tape or a page of paper, but did away with the need for synchronous transmission; using instead a start-stop method. While the start-stop method does require higher quality transmission links than synchronous method, since a noise pulse could be taken for a start pulse, the advantages far outweight the slight increase in bandwidth required.
While the PKT printer was considerable smaller and lighter than the "Hell" printer, the majority of the space and weight were devoted to mechanical apparatus necessary for operation. […]
[…] 1) Patent 8101 Klasse 21a1, Gruppe 17, Anmeldetag: 29.7.1952, Fernschreiber [Teletypewriter]; 2) Patent 15749 Klasse 21a1, Gruppe 7/01, Anmeldetag: 29.7.1952, Umschalteinrichtung für Fernschreiber, bei dem die Schriftzeichen in Rasterpunkte zerlegt sind [Coding equipment for a Teletypewriter at which characters are consisting of dots (RASTER - points)]; 3) Patent 15759 Klasse 21a1, Anmeldetag: 29.7.1952, Schreibkopf für Raster-Fernschreibmaschine [Recording head for Matrix type (RASTER) Teletypewriter]; 4) Patent 9043 Klasse 21a1, Anmeldetag 17.1.1953, Fernschreiber [Teletypewriter]; 5) Patent 12196 Klasse 21a1, Anmeldetag 24.6.1954, Schreibkopf für Fernschreibmaschine [Recorder for Teletypewriter] […](8 pages)
