US2510577A - Keyboard lock for typewriting machines - Google Patents

Description

June 6, 1950 A. c. Ho| T 2,510,577

KEYBOARD Locx FOR TYPEWRITING MACHINES Filed June 5. 1947 INVENOR ALBERT HOLT m2 www ATTO R N EY Patented June 6, 1950 KEYBOARD LOCK FOR TYPEWRITING MACHINES Albert C. Holt, Ridgewood, N. J., assigner to International Business Machines Corporation, New York, N. Y., a corporation of New York Application June 5, 1947, Serial No. 752,720

7 Claims.

This invention relates to typewriting machines, more particularly to that class of typewriting machine which is operated by motor power.

An object of the present invention is to provide an improved key locking device.

Another object is to provide a key locking device which is actuated by the end-play of a suitable shaft or other rotary member with which the machine is ordinarily provided.

Other objects of the invention will be pointed out in the following description and claims and illustrated in the accompanying drawings, which disclose, by way of example, the principle of the invention and the best mode, which has been contemplated, of applying that principle.

In the drawings:

Fig. 1 shows the key locking device as applied to a conventional form of electrically operated typewriting machine and shows the keys in locked condition.

Fig. 2 is a View similar to Fig. l but showing the keyboard unlocked.

The invention is shown in the drawings as applied to the well known Electromatic power operated typewriter but it will be understood that this disclosure is purely for convenience in making clear the nature of the invention and that the invention may be applied to other power operated typewriters or other oflice machines.

The numeral ID designates one of the usual character keys of the keyboard, which key is suitably pivotally mounted at II on a cross rod supported by the main framework and at its front end is guided in a slot formed in the usual key guide comb I2. The key locking bar I3 is in the form of a vane pivotally mounted at I4 in the main framework and normally extends vertically (Fig. 1) so as to lock all of the keys against depression. Ordinarily this key locking bar I3 is mechanically connected to the lever of the switch which turns on current to the usual driving motor and is arranged so that when the switch is on the key locking bar I3 is in the position shown in Fig. 1.

In the present case provision is made for operating the key locking bar I3 so as to render it ineffective when the machine is started, which means is arranged to become automatically effective to lock the keyboard as soon as anything happens which would cause the machine to stop. For example, it sometimes happens that the usual extension cord connecting the machine to the current outlet becomes disengaged from the outlet without the operators knowledge, with the result that keys are often operated before it is Vdiscovered that the motor is not running. This is very apt to happen in a noisy room. As soon as current is placed on the machine then all of the function devices controlled by the operated keys become effective at once and are partially operated. Usually a sufficient number of character keys are depressed to cause a plurality of type bars to operate at once with the result that they jam in the type basket and stall the motor.

According to the present invention advantage is taken of end-play which may be incidental to some rotating part in the machine or some part which may be caused to have end-play for the purpose of operating the key locking bar I3. A machine of this type is usually provided with some form of worm reduction gear because of the fact that small appliance motors are necessarily of the high speed type in order to obtain the necessary amount of power with a small compact motor.

In the drawings, I5 generally designates the usual worm reduction gear found in the well known Electromatic typewriter. This reduction gear consists of a suitable housing within which is journaled a worm Wheel IB driving the usual power roller I1 for the type bars and other instrumentalities and mechanisms of the machine. This power roller rotates in the direction of the arrow all of the time the machine is in use. Meshing with the worm wheel I6 is a worm I8 formed in a spindle I9 turning in the fixed bearing 20 and in a threaded end plug 2|. At its left hand end the spindle I9 is provided with a cross pin 22 extending into slots formed in the end of the motor shaft 23.

The spindle I9 is slidable in the bearing 29 and the end plug 2| and when the machine is at rest, occupies the position shown in Fig. 1 with rthe pin 22 at the closed end of the slot in the shaft 23. The spindle I9 is held in this position by a spring 24 interposed between a collar or enlargement I9a on the spindle I9 and the bearing 29. 'Ihe right hand end of the spindle I9 is rounded and engages a lug formed in an L-shaped lever 25 pivoted at 26 to a Xed part of the machine. This lever 25 is urged in a clockwise direction into engagement with the end of spindle I9 by a torsion spring 21. One arm of the lever 25 is slotted to embrace a pin 28a formed in a lever 28 pivoted at 28h to a xed part of the machine. The lever 28 has a pin and slot connection 2919 to an arm 29 secured to the key locking bar I3. The spindle I9 also has an enlargement I9b designed to limit rightward movement of the spindle I9 by engaging the plug 2l.

The worm housing is usually filled with a relatively stiif, heavy grease which naturally makes the worm Wheel I6 turn a little stiiily in the housing and this stiifness is augmented by the friction of the shaft for the worm wheel and various other parts which are connected to or normally driven by the worm wheel. Furthermore, the power roller i? is quite long and fairly heavy and it also has considerable inertia. The spindle I9, on the other hand, is relatively small and the worm I8 is above the normal level of the grease or oil in the worm housing and, due to the smaller shaft size, tends to turn comparatively freely.

When the operator closes the switch which energizes the motor, the motor shaft 23 and the spindle iS turn in the direction of the spiral arrow in Fig. 1. Due to the stiffness of the grease, the friction of the bearings and the inertia of the power roller, the worm i9 initially travels to the right to the position of Fig. 2 by a screwing action before producing any movement of the power roller Il or the worm wheel I6. This movement `of the spindle I9 causes the lever 25 to be rocked counterclockwise, moving the key locking bar .i3 in the same direction, through the lever 23, to

the position of Fig. 2. As soon as the stop por- .r

tion I 9b strikes the plug ZI the worm I8 will turn the power roller and the parts will be maintained in this position as long as the motor remains in operation.

If the switch is opened or if the connecting cord to the motor is pulled out while the machine is in operation the motor will immediately slow down and stop and allow the spring 2d to push the spindle back to the position of Fig. 1, thereby locking the keys against operation. ylhus, if the power should fail while the machine is running, the keyboard will be very quickly locked.

While there have been shown and described and pointed out the fundamental novel features of the invention, as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It isthe intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

l. In combination with the keys of a typeriting machine, a key locking member, a power driving train including a member having an initial end-play when the driving train is s and means actuated by sad end-play for dis abling the locking member.

2. In combination with the function keys of a typewriting machine, means to lock said keys against operation, a power roller for actuating the function devices controlled by said keys, a driving motor, gear means connecting said moto-r to said power roller and including a. member having va lost motion incidental to starting said motor, and means actuated by the lost motion of said member for disabling said locking means.

3. In combination with the function keys of a typewriting machine, means to lock said keys against operation,l power mechanism for actuating the function devices controlled by said keys, a driving motor, driving connections between said motor and said power mechanism including a member having an end-play movement when said motor starts to drive said power mechanism, and means enabling said end-play movement to disable said locking means.

4. In combination with the function keys of a typewriting machine, means to lock said keys against operation, power mechanism for actuating the function devices controlled by said keys, a driving motor, driving connections between said motor and power mechanism including 3, worm 'wheel connected to said power mechanism and a worm connected to said vmotor and having a limited axial motion, when said motor is started, in consequence of a threading movement between the worm and worm wheel; and mean actuated by said worm in its axial movement for releasing the locking means.

5. lin combination with recording means and selectable devices for controlling the recording means, means for locking the selectable devices against operation, power mechanism for actuating the recording means under control of said selectable devices; motive power means for the power mechanism, including an element having a take-up motion when the motive power means is started, and means enabling said take-up motion to disable said locking means.

6. in combination with the keyboard of a keyboard controlled machine, means to prevent operation of the keyboard, power operating means controlled by said keyboard, a power driving train for said power means, including a member having an initial idle take-up motion when the driving train is started, and means responsive to said idle motion for disabling said preventing means.

7. In combination with the keyboard of a keyboard controlled machine, means to prevent operation of said keyboard, a main power actuator for the function devices controlled by said keyboard, a motive power unit, and driving connections between said main power actuator and said power unit, including a member having a preliminary idle motion for disabling the pre venting means before the actuator is started in operation "by the power unit.

ALBERT C. HOLT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,940,155 Thompson Dec. 19, 1933 2,287,475 Helmond June 23, 1942

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