Patent GB-633752-A (GB)
Title: Improvements in or relating to printing telegraph receivers
IPC: H04L17/24
Filed: 1946-04-30
Abstract: 633,752. Printing - telegraph receivers. CREED & CO., Ltd., and SALMON, R. D. April 30, 1946, No. 14861/48. Divided out of 620,682. [Class 40 (iii)] A printing-telegraph receiver adapted for the printing of characters, some of which require a greater character-spacing than others comprises means operative upon the receipt of a signal representing a character to effect the required character-spacing. To effect printing in Arabic script, a six-unit code is employed, and as the number of wide characters is much greater than that of the narrow characters, double spacing is normally employed and this is reduced to single spacing on the reception of the code signal of a narrow character. The signal combinations are allotted so that a number of wide characters in the upper and lower cases have an initial code element of the same nature, e.g. spacing, whilst some narrow characters are selected in the lower or upper case by having two initial marking impulses, and the spacing for other characters having identical code combination is determined by the nature of the initial code element, e.g. marking, in combination with the position of a case-shaft selector member. The operation of the code function members and function members, Figs. 1, 2 (not shown), is similar to that described in Specification 620,682, and a function member, such as 165, controls the operation of single or double spacing. A function shaft 49 is arranged to rotate at twice the rate of that of the shaft of the translator cam 134'in order to effect the double spacing allotted to the wide characters. When a lever 135 is permitted unrestrained movement into the recess of the cam 134, its extension 144 engages an extension 145 of a lever 146 which removes a detent 139 from engagement with a pivoted pawl 137, allowing the function cam sleeve 133 to be clutched to the shaft 49. The end of the lever 146 is latched by a pivoted detent 161, and during the first revolution of the shaft 138 a projection 163 rocks and restores a pivoted latch 164 and later rocks the detent 161 so that the end of the lever 146 is held by the latch 164. During the second revolution of the shaft 49, the lever 164 is again rocked and the lever 146 is fully released so that the pivoted detent 139 is positioned to engage the pawl 137 and to disconnect the function cam sleeve 133 from the shaft 49. When single spacing is to be effective, the inward movement of the function bar 165 allows the projection 170 to move upwardly behind a projection of the arm 171 of the lever 135 before it engages in the recess of the cam 134 so that the extension 144 does not move sufficiently far to allow the lever 146 to be latched by the detent 161, and the pawl 137 is released during the first revolution of the shaft 49. With the wide characters, the second spacing movement is preferably effected after the printing of the character. A second detent 150 similar to the detent 139 prevents rebound when the sleeve 133 is arrested. The Provisional Specification describes an arrangement in which a detent lever controlling the release of the function camsleeve is formed with a four-tooth rack arranged to co-operate with teeth carried by a lever controlled by a cam on the function cam-sleeve and forming therewith a four-step escapement. The detent lever also carries an extension co-operating with one arm of a three-armed lever having second and third arms associated with a cam on the translator cam-sleeve and an interposed member controlled by a function bar responding to single-space characters so that the extent of movement imparted to the threearmed lever by the cam on the translator cam sleeve is reduced. The arrangement is such that the detent lever 'has an extended movement for double-spacing and is only partially restored towards its normal position during the first revolution of the function cam-sleeve. Specifications 600,299, [Group XL (c)], and' 620,686 also are referred to.