Patent GB-117512-A (GB)
Title: Improvements in and relating to Sound-deadening Arrangements for Typewriters.
Inventor: POWERS FRANK BANGS
IPC: B41J29/08
Filed: 1917-07-30
Abstract: 117,512. Powers, F. B. July 30, 1917. Sound-deadening cases; electric and pneumatic driving-mechanism; keyboard operators.-A typewriter and independent relay-mechanism for operating the keyboard and the carriage are enclosed completely in a sound-deadening case and a keyboard is provided outside the case for controlling the relay mechanism. The sound-deadening case may be provided with multiple walls and the. case and the wall spaces may be exhausted, or be packed with sound-deadening material. In a modification, the case consists of a single wall of sound-deadening material or of a single-walled exhausted chamber. (1) In the apparatus shown in Fig. 1, the typewriter 11 is enclosed in a double-walled case A, a partial vacuum being maintained in the wall space and a higher partial vacuum in the case. The case consists of a base, a hinged top-section A', and a front section D which is mounted at one side on a vertical hinge and is provided with a screw fastening for drawing the section against the base. The hinge 10 of the section A' is provided with a spring which automatically opens the section when the interior of the casing is connected to the atmosphere, a toggle 33 limiting the opening movement. The sections are seated by rubber distance-pieces d and are permanently in communication through flexible tubes 7. The section A' is provided with windows E and an electric lamp 72. A frame 20, mounted on the section D, carries a set of pneumatic devices 15, provided with plungers 39, Fig. 4, for operating the keys 12 of the typewriter, the operation of the plungers being controlled bv keys 13. The devices 15 each consist of a cylinder provided with a piston 63 carrying the plunger 39, the space below the piston being in communication with the case A. The upper part of the cylinder is formed with chambers 62, 61 which are in communication through tubes 16, 17, respectively, with the atmosphere and a vacuum space u, a valve 42 being provided for placing the chamber 62 or 61 in communication with the space above the piston 63. On depressing any of the keys 13, the valve 42 in the associated device 15 is operated and the piston is depressed by the pressure in the chamber 62. On release of the key 13, the piston is returned, since the pressure within the case A is greater than that in the chamber 61. The two tubes 16, 17 are common to the set of devices 15 and are each provided with a flexible connexion for permitting the opening of section D. The tube 16 is provided at the outlet with a screen 19. To permit of operation of the typewriter when the top section A' of the case is open, or to increase the pressure on the keys, the tube 16 can be placed in communication with a pressure chamber 21 by means of a valve 18. The case A is supported by a cabinet a provided with a double-walled chamber B containing exhaust pumps r and a compression pump r<1> which are driven by a motor s. The inner chamber communicates by means of a valve 1 with the wall space u. The pumps r maintain a high vacuum in the wall space u and the inner chamber B, and the pump r<1> compresses the air in the chamber 21. The space u is connected to the tube 17 and is also connected by tubes y, w respectively to the wall space of the case A and to the interior of the case. Automatic devices are provided for cutting off connexion between the tubes y, wand the space u when the required exhaustion has been produced in the spaces with which these tubes communicate. These devices consist of valves y<1>, w<1> which are closed by springs and are opened by solenoids 3, 5 in circuit which are controlled by the hands of vacuum gauges 2, 4. A vacuum gauge 6 is also provided for controlling the speed of the motor. The tube w is provided with a valve 8 for placing the interior of the case A in communication with the atmosphere. (2) In the apparatus shown in Fig. 5, the case J consists of a single-walled chamber which is exhausted through a tube 47. The keys 12 of the typewriter 11 are operated by solenoids 44, the external keys 45 being arranged to close contacts 46 in the circuits of the solenoids. In a modification, suitable for electric actuation, the case is multiple-walled but the wall-spaces and the case are not exhausted. Solenoids may be provided for assisting in holding the sections of the case in closed position. Pneumatic carriage-returning and letter-spacing mechanism.-(1) In the apparatus shown in Fig. 1, the carriage is returned by means of a pneumatic motor 24 arranged inside the case A, the linespacing lever 29 of the typewriter being connected to an arm 25 on the piston of the motor by a cord 26 which passes over pulleys 28. For carriage-return, a valve 18<1> is operated to place the left-hand end of the motor cylinder in communication with the tube 16, which can be placed in communication with the atmosphere or the pressure chamber 21 During letter-spacing, the valve 18<1> is operated to place the left-hand end of the motor cylinder in communication with the interior of the case A. (2) In the apparatus shown in Fig. 6, the carriage is propelled for letter-spacing by a pneumatic motor 24<1> and is returned by a pneumatic motor 24. The line-spacing lever 29 is connected by a link 70 to an endless cord 26 which passes over pulleys 28 and is coupled to a rod 25 which is common to the pistons of the motors. The operation of the motors is controlled by a valve 18', which can be set to place the motors 24', 24 in communication with the atmosphere and a vacuum space or vice versa. The line-spacing lever is resisted by a spring which yields when the carriage is arrested at the end of the returning movement.