US2341481A - Typewriting machine - Google Patents

Description

8, 4 J. A. B. SMITH v 2,341,481

TYPEWRITING MACHINE Filed June 19, 1941 I JINVENTOR M55554. 5. .5/7/7/7 ATTORN EY Patented Feb. 8, 1944 TYPEITING MACE Application June 19, 1941, Serial N0. 398,795

3 Claims.

- ter on a stencil or other work sheet is to conform to a certain arrangement, such as that of printed blank form sheets on which the typed matter is to be reduplicated, the procedure of typing the stencil or work sheet to conform to the printed blank is usually difficult and tedious on'the conventional typewriter.

It is generally known to overcome these difficulties by providing illumination in back of the work sheet so as to project light rays through the work sheet during the typing work. In one instance it has been proposed to provide a hollow translucent platen within which electric lighting elements are arranged, by which illumination through the work sheet at the region of the printing point is had. Such devices, however, have been found to be impractical by reason of the difliculties encountered in supplying current to the light elements within the rotatable platen, and in the dissipation of heat imparted to the platen by these encased light elements, as well as the excessive expense involved in producing a device of this character. Some other devices proposed involve somewhat costly structure, frequent manipulation or adjustment to obtain satisfactory service, and cause unnecessary eye strain and resultant fatigue to the typist.

The present invention has for one of its objects the provision of an improved illuminating means in association with the sheet-holding and feeding means of a typewriter, which obviates the foregoing objectionable characteristics and difficulties in operation.

Another object is to provide an illuminating device for stencil-cutting typewriters, which forms a component part of the machine in readiness for immediate use to illuminate the typing line from in back of the work sheet, and so arranged as not to hamper, in any way, the use of the machine in conventional typing.

A further object is to provide a typewriter illuminating system including a light source and a. translucent platen roll forming part of the sheet-holding and feeding means of the typewriter, the platen roll having characteristics which afford proper backing for the type impressions and assure dependable, accurate holding of the work sheet.

Another of the objects is to provide a stencil typewriter illuminating system which will give ample back-of-the-work-sheet illumination to the I typing line, rendering the type impressions on the stencil sheet easily visible, but shutting 03 i1- lumination to the other areas or the work sheet so as to eliminate glare and minimize eye fatigue.

In the drawing:

Figure l is a fragmentary perspective view of a typewriter embodying the invention,

Figure 2 is a perspective view of the rear portion of the typewriter, showing the preferred arrangement of the wiring, and

Figure 3 is a fragmentary transverse sectional view on a fore-and-aft plane of the typewriter.

In the preferred embodiment of the invention illustrated, the typewriter is of the usual front strike kind in which type bars 5 actuated by operation of key levers t are arranged to strike a platen roll I at the front thereof at a printing point defined by type guides 8. The platen roll 7 is rotatably mounted in a carriage it arranged to travel transversely of the typewriter in letterfeed and return directions on trackways II, the carriage during typing being impelled by the usual drum spring and under control of a letter-feed escapement, a ratchet wheel l2 of which is geared to the carriage at l3. The type bars 5, in approaching the platen, engage a universal bar I l causing the escapement mechanism to feed the carriage in line-typing direction at letter-space increments, so that the successive type impressions are arranged at letter-space intervals on the typing line.

A. paper shelf I5 extends around the lower portion of the platen and issues upwardly and rear wardly therefrom in a paper rest to facilitate the insertion of a work sheet into the machine'around the platen. The paper or work sheet is fed to effect line spacing in the usual manner by rotating the platen roll 1 upon operation of the usual line-space mechanism actuated by a line-space and carriage-return lever 56. Bottom feed rolls ll are spring pressed against the platen roll to cooperate therewith in feeding the paper. Front feed rolls l8 may also be provided to cooperate with the platen in a region just above the printing line to hold the paper snugly against the platen.

In accordance with the invention, the platen roll 1 is constructed of a suitable translucentmaterial such, for example, as glass or other solidified plastic composition adapted to form a substantlally solid cylinder or roll through which light rays may pass transversely. Accurate feeding of the work sheet in process of being typed requires a platen periphery of frictional character so that the paper pressed against the platen by the feed rolls I! may be securely held in position and may be accurately line spaced when the platen is rotated. The cylindrical surface of the platen is, therefore, roughened to provide this necessary friction on the work sheet, the roughening being of a relatively fine texture or grain to assure a suitable backing surface for the type impressions. The surface texture may be, for instance, like frosted glass, a minute knurling or a closely-spaced ribbing generally lengthwise of the platen, such as may be formed by draw filing or drawing the platen through a suitable die, if the platen material is relatively soft and susceptible to tooling.

A light source 20 such as an electric incandescent bulb, a gaseous discharge tube or a fluores-' cent lamp, is arranged at the side of the platen roll opposite the printing point, in such position that the light rays issuing therefrom pass through the translucent platen I and penetrate the work sheet at the printing point, along substantially the entire typing line. The indirect rays from the light source are reflected toward the platen by a combined reflector and shield 2i extending substantially over the entire length of the platen roll. The curved portion of the renector-shield directly opposite the platen forms a concave cylindrical reflector which serves primarily to turn the indirect rays toward the platen, its curvature being substantially parabolic, approximating a curve of uniform radius with the center of the light element or its filament as the focal point of the reflector. Thus, a large portion of the indirect 'rays are re-directed by the reflector to pass through the platen, to the typing line. As shown, the reflector-shield extends forwardly and downwardly from the reflector portion, toward the platen, having its longitudinal edge practically touching the platen and as close as possible to the typing line without interfering with the operation of the front feed rolls l8 or with the insertion 'or feeding of the paper in the machine. This arrangement of the reflector-shield, extending at its front to a line along and adjacent the typing line on the platen, serves to eliminate excessive glare to the typists eyes by shutting off light rays that may be reflected off the platen periphery through the leading portion of the work sheet. This front edge of the reflector-shield may be so positioned as to illuminate the desired minimum number of typing lines preceding the line on which the typing is done. It will be seen that the entire illuminating fixture, including the light element 20, the reflector-shield 2i and the support therefor may occupy the space afforded at the platen between the leading and trailing portions of the work sheet directed around the platen, leaving an ample passage in front of the paper rest l through which the work sheet is easily inserted.

The illuminating element and reflector-shield forming the lighting fixture are supported as a unit on the carriage. The lighting fixture may include an elongated base 22 arranged to straddle the entire length of the platen and having brackets 23 at each end by which the fixture is secured to each end member 24 of the carriage. Each bracket 23 may include a plate-like lug which rests on the carriage end member and underlies the cover member 25 thereof, being held the carriage ends.

in place by screws 26 securing said cover member to the carriage. Sockets or other'suitable holders 21 for mounting the illuminating element 20 may be secured, as shown, to the base member 22 and are arranged thereon to support the light element with its longitudinal axis parallel to the axis of the platen.

The light element 20. illustrated is a tubular fluorescent lamp having electrical terminals at each end and requiring a receptacle or holder 2'! at these ends, into which the terminals fit and make contact with the electric current supply. The two holders 2? may be secured as shown to the base member 22, supporting the tubular lamp between them. Fluorescent lamps usually require auxiliary equipment such as a reactance or ballast unit and a starting relay switch, to control the current delivered to the lamp and assure proper starting. To avoid imposing extra weight on the typewriter carriage, this equipment may be contained in a unit 28, see Figure 3, which is secured preferably to the main frame of the typewriter on the rear panel thereof, and has two electric cords 30 issuing therefrom and connected to the two lamp holders 2'! adjacent The two electric cords 39 may be fastened to the carriage ends, as by clips 3!, each cord having suflicient slack between the clip 3i and the unit 28 to allow full travel of the carriage. A supply cord 32 connects the auxiliary unit 28 to the electric service supply.

It the illuminating element 20 used is of such character as not to require the auxiliary unit 28, as in the instance of the usual electric bulb or a Luminite tubular lamp, a terminal connector block may take the place of the unit 28, being secured to the rear panel of the typewriter. The electric cord or cords 30 to the illuminating element 20 on the carriage may be connected. at this terminal block to the service cord 32 which is adapted to be plugged in at the electric supply outlet.

It will now be apparent that the invention provides an improved illuminating means in association with the sheet-holding and feeding means of a typewriter, by which the stencil typing is rendered easily visible during the progress of the work. The illuminating device forms a component part of the machine, being mounted in position on the typewriter carriage in readiness for immediate use to illuminate the typing line from a region in back of the work sheet. The provision of the reflector-shield as shown assures the efiicient use of a minimum supply of light which is directed through the translucent platen l to the typing line. Some of thelight rays passing into the platen are thrown against the roughened platen periphery and are thereby re-directed or reflected at various angles within the platen, producing a generally diffused, soft light along the entire platen periphery at the typing line. To minimize the glare to the typists eyes, the reflector shield 2| may be arranged to extend as close as desired to the typing line, so that only that area of the work sheet to be observed during the process of typing is illuminated. The typewriter constructed according to the invention may be used with facility for conventional typing without any adjustment or rearrangement of parts, in that the entire illuminating system is so arranged as to enable the machine to be operated for the usual typing work, upon setting the usual ribbon selector to the desired color band.-

What is claimed is:

1. In a front strike .typewriting machine having a traveling carriage rotatably mounting a platen roll and presenting a paper rest extending under the platen roll and upwardly and rearwardly therefrom, and printing instrumentalities adapted to strike the platen roll along a typing line at the front thereof during travel of the carriage, the platen roll being translucent; an elongate illuminating element supported on the carriage and arranged longitudinally thereof, in the valley formed by the and an elongate reflector-shield backing said illuminating element and extending forwardly therefrom to a line along the platen roll adjacent the printing line, to substantially shut off from a work sheet on the platen .roll the light rays reflected off the periphery thereof.

2. In a front-strike typewriter having a traveling carriage, a translucent platen roll on the carriage, an elongate illuminating element supported on the carriage longitudinally of the platen roll in position to project light rays through the platen roll to illuminate substantially the entire printing line at the front thereof, and an platen roll and paper rest,

elongate reflector-shield including a curved portion partly surrounding the illuminating element and arranged to reflect light rays to the platen and including a generally flat portion extending forwardly and downwardly to a margin at the platen roll close to the printing line, to shield superfluous light rays from the typist.

3. In a front-strike typewriter having a travel ing carriage and a translucent platen roll on the carriage, a device for illuminating a work sheet on the platen roll from in back of the work sheet, comprising a supporting member reaching substantially from end to end of the carriage and fixedly secured to the carriage end members, holding elements on said supporting member to mount an elongate illuminating element in fixed position to project light rays through the platen roll to the work sheet, and areflector-shield arranged to overlie and embrace the illuminating element and extending forwardly and downwardly to align along the platen roll adjacent the printing line, thereby to illuminate only a minimum band of the work sheet, along the printing line.

JESSE A. B. SMITH.

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