US1150498A - Platen-shifting mechanism. - Google Patents

Description

T. E. BUSCHMANN. PLATEN SHIF'HNG MECHANISM.

' APPLICATION FILED JUNE 25, I913. 1,150,498.

Patented Aug. 17,1915.

2 sHsns-snsn 1.

T. E. BUSCHMANN. PLATEN SHIFTING MECHANISM. APPLICATION FILED JUNE 25. I913.

Patented Aug. 17, 1915.

EST 2.

2 SHEETS-SH THEODOR EUGEN BUSCHMANN, 0F CNITZ, GERMANY, ASSIGNOB, 'JM'.) THE E OF WANDERER WERKE VORM. W 5.; NEAR CHEMNITZ, GER-MANY.

-=OFER & JAENICKE, ABM-GEES 015' SGHON'AU,

PLATEN-STING MEG:

Specification of Letters Patent.

Application filed June 25, 1913. Serial No. 775,791.

To all whom it may concern Be it known that LTHEODOR EUGEN Boson- MANN, a subject of the Emperor of Ger-' many, residing at Chemnitz, Germany, have invented certain new and useful Improvements in Platen-Shifting Mechanism, of which the following is a specification.

This invention has for itsobject to provide an improved mechanism for shifting the platen in typewriters into the upper case position. As is well known, in the ma orlty of such mechanisms the platen is raised for the purpose of writing capitals or upper case characters. Now since in such cases the platen is not fixed in position, it must be held in its normal position preferably by means of a catch or locking device, while means must also be provided for limiting the extent of its rising movement when being shifted.

Means have already been proposed for holding a platen in its lower case position and limiting its upward movement into its upper caseposition, but such known means have comprised a locking member situated outside of the shifting mechanism.

Now according to the present invention the members of the platen shifting mechanism are so constructed that they effect of themselves the desired movement of the platen into its end positions. For this purpose, controlling members are interposed in the shifting mechanism, and are mounted on the shifting platen carrier (more particularly on the shifting frame) and they are arranged to-cooperate with each other in such a manner that one of these members will always be in its holding position when the other member is in released position. To this end there are preferably employed two toggle levers which engage the shifting frame and are moved by the shift key through the medium of bell crank levers, in such a manner that one toggle lever will be extended when the other toggle lever is bent.

It is to be understood that also other members may be interposed in the shifting mechanism to assist the operation. It is also to be noted that one advantage of the improved mechanism is that the platen is moved almost noiselessly into its several end positions.

Une form of this invention comprising the use of toggle levers is illustrated by Way of example in the accompanying drawings, in which Figure 1 is a side elevation partly in section of a type-writer fitted with the improved shifting mechanism. Fig. 2 is a corresponding partial front elevation partly in section. Fig. 3 is a partial side elevation similar to Fig. 1, but showing the parts in a different working position. Figs. 4 and. 5 are views correspondin respectively to Figs. 1 and 3, of a modi cation.

As shown, the platen 1 which is adjustably mounted and guided in the carriage 2, rests by means of a sliding roller 4: on a shifting frame 5. This frame is adapted to slide at its upper end in guides 15 fixed to the framing 3 of the typewriter, and it is supported at its lower end by a radius rod 14, which is pivoted to the typewriter framing 3.

The shifting frame 5 has a bent over portion or lug 6 carrying a pin on which the levers 11 and 12 are pivoted. The lever 11 is jointed to a bell crank lever 10 which is pivoted to the typewriter frame, the arrangement being such that one arm of this bell crank lever 10 forms a toggle with the pivoted lever 11. The other arm of the bell crank lever 10 is jointed to a rod 9 to the other end of which there is jointed an arm of a bell crank lever 13 likewise connected to the framing 3. The other arm of this bell crank lever 13 forms a toggle with a pivoted lever 12. To the rod or link 9 there is jointed a radius rod 8 which is connected to the shift key 7.

In the construction shown in Figs. 4- and 5, there is mounted on the pin in the lug 6 of the shift frame 5 a lever 11 as before, and also a lever 17 which engages, by means of a hooked extension, the lever 11. In this arrangement the lever 11 is connected to a lever 16 pivoted to the typewriter frame 3 and it forms a toggle herewith. The lever 17 is jointed at its other end to a bell crank lever 13 which is connected by a radius rod or link 18 to the shift key lever 7.

The bell crank levers 10 and 13, and the lever 16 are fulcrumed on bolts 20 secured in'the usual manner by nuts in the typewriters framing 3. These bolts are formed under their heads with eccentric collars or shoulders 21 (Fig. 2) for the purpose of enabling the toggle levers to be adjusted relatively to each other.

The operation of the improved mechanism constructed as shown in Figs. 1, 2 and 3, is as follows: In Fig. 1, the platen is shown in its lower case position, in which the toggle 10, 11 is extended, and the toggle 12, 13 is bent. In this position the platenis held by the extended toggle 10, 11 and protected from being moved by jolts or similar influences. If now for instance, the shift key 7 is held down for the purpose of writing capitals, the rods 8 and 9 are raised.'the upper arm of the bell crank lever 10 is turned upward toward the right, and the toggle 10, 11 is bent. At the same time the toggle 12, 13 is extended so that the parts assume the position shown in Fig. 3. The extended position of the toggle 12, 13 determines, that is, limits the movement of the platen. This movement may be altered, and a fine adjustment be efiected by means of the bolts 20 with the eccentric collars or shoulders 21. On releasing the shift key, the load or weight of the rod 9 and link 8, as well as the excess load due to the rear end of the shift key lever 7, are shifted from the end of the key lever to lever arm of the bell crank lever 13 that is pivoted to the lower end of link 8. If the shift-key lever 7 be provided with a retracting spring, as is customary, the pull of this spring is also transferred to the bell crank 13. This load,

whether the retracting spring be present or not. acts on the bell crank lever 13, being multiplied by the length of the bell crank arm connected to the bar 9 to give this'lever a slight impulse and move it off its dead center, whereupon an additional load due to the excess weight of the platen 1 (which is otherwise counterbalanced) forces the'shift frame 5 downward, thereby reextending the toggle 10, 11 turning down the upper arm of the bell crank lever 10 and carrying the rod 9 down with it. By this means the bell crank lever 13 is turned down again, and the toggle 12, 13 is bent again.

In the construction shown in Figs. 4 and 5, on holding down the shift key 7, the bell crank lever 13 is turned up toward the right through the medium of the link 18, and the toggle 13, 17 is extended, whereby through the medium of the hook 19 engaging behind the lever 11, the toggle 11, 16 is bent. The return of the parts of the shifting mecha- Although the present invention has been described by way of example in its appli-' cation to a typewriter having a shift frame it is to be clearly understood that it is not limited to typewriters of this kind, and that the invention. is applicable to all shifting carriers or supports for paper rollers.

I claim 1. In a typewriting machine, the combina: tion with the frame, a vertically movable platen carrier and a shift key lever; of raising and lowering mechanism for the carrier including two toggles arranged substantially in the plane of said lever and above one another, a pivot on said carrier at the adjacent ends of said toggles and common to both of them, means to pivotally mount the opposite ends of the carrier on said frame, an arm extending from one member of one of the toggles that is ivoted on said frame, to form a bell-crank ever therewith, and a link connecting said mechanism and key lever.

2. In a typewriting machine, the combination with a shiftable platen carrier and a platen shifting key lever; of two toggles connected to said carrier and operating alternately, means on one of said toggles to automatically break the other of said toggles when straightened, and means to operatively connect one of the toggles to said key lever. I

3. In a typewriting machine, the combination with a shiftable platen carrier and a platen shifting key lever; of two toggles having their adjacent ends pivotally connected to said carrier, one member of one of the toggles constituting a bell-crank lever and the other member thereof having an extension arranged to engage the other toggle, and means to connect said bell-crank and key lever.

In testimony whereof I have affixed my signature.

THEODOK EUGEN BUSCHMANN. In the presence of- EMIL STEGER, WALTER Koran-3R.

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