US3920114A

US3920114A - Release and blocking mechanism for power operated typewriters

Info

Publication number: US3920114A
Application number: US504413A
Authority: US
Inventors: Richard E Shattuck; Albert H Cryder
Original assignee: SCM Corp
Current assignee: Smith Corona Corp
Priority date: 1974-09-09
Filing date: 1974-09-09
Publication date: 1975-11-18
Anticipated expiration: 1992-11-18
Also published as: JPS5156321A; FR2283784B1; CA1037404A; JPS5545036B2; DE2539796A1; GB1496409A; FR2283784A1; IT1042391B; DE2539796B2

Abstract

A shift release mechanism is connected to an electrical switch and to a control knob on a power operated typewriter. Operating the control knob actuates the electrical switch from a closed state to an open state and actuates the shift release mechanism for releasing a shift keylever to cause a platen supporting carriage to move from an upper position to a lower position. The shift release mechanism further includes a finger positioned to block the depression of the shift keylever when the electrical switch is in the open state.

Description

United States Patent [1 1 [111 3,920,114

Shattuck et al. 5] Nov. 18, 1975 RELEASE AND BLOCKING MECHANISM OTHER PUBLICATIONS F R POWE WR 0 R OPERATED TYPE ITERS IBM Technical Disclosure Bulletin, Vol. 4, No. 12,

[75] Inventors: Richard E. Shattuck; Albert H. M 1962 20 & 21

Cryder, both of Cortland, NY.

[73] Assignee: SCM Corporation, New York, NY. Primm'y Examiner paul Shapiro D Attorney, Agent, or Firm-Milton M. Wolson, Esq.; [22] Filed: Sept. 9, 1974 Stanley Klem 21 Appl. No.: 504,413

[57] ABSTRACT A shift release mechanism is connected to an electril97/lgziJl Cal Switch and to a Control knob on a power Operated [58] Fieid 80 107 12 typewriter. Operating the control knob actuates the electrical switch from a closed state to an open state [56] References Cited and actuates the shift release mechanism for releasing a shift keylever to cause a platen supporting carriage UNITED STATES PATENTS to move from an upper position to a lower position.

2,304,357 12/1942 Helmond 197/80 The hift relea e mechanism further includes a finger 2,499,053 2/1950 Bu chel r r r r 197/80 positioned to block the depression of the key- 2,506,703 5/1950 Chisholm l97/107 lever when the electrical Switch is in the Open state 3,349,886 10/1967 Madison et al. 197/107 3,572,488 3/1971 Kuramochi 197/80 X 6 Claims, 3 Drawing Figures Sheet 1 of 2 U.S. Patent Nov. 18, 1975 U.S. Patent Nov. 18, 1975 Sheet 2 of 2 3,920,114

RELEASE AND BLOCKING MECHANISM FOR POWER OPERATED TYPEWRITERS BACKGROUND OF THE INVENTION The present invention relates to power operated typewriters and more particularly to a shift release and blocking mechanisms for a carriage shift control mechanism.

lnactivating various functions of a power operated typewriter, when the power is turned off, to prevent damage to the mechanism or injury to the operator has been recognized as a perennial concern within the typewriter industry.

Shift release and blocking mechanism in the prior art have included bails that were actuated by opening a switch. The bail conditioned all keylevers to be inoperable but did not disengage any function keys that were already depressed. Consequently, when the switch was closed, the typing function, that was actuated by the depressed function key, completed itscycle. In most cases, the added strain placed on the power source by the completing function cycle combined with the strain of bringing the typewriter mechanism to operation readiness could overload and cause damage to the power source.-

In the event that the function selected was a carriage return function and the operator was cleaning the typewriter, a sudden carriage return cycle could cause injury. 1

None of the prior art teaches a mechanism that releases a function key when the electrical switch is conditioned to an open state and renders the key inoperable until the switch is in a closed state.

SUMMARY OF THE INVENTION Briefly described, the present invention teaches a shift release and blocking mechanism for a shift mechanism-of a power operated typewriter. The shift mechanism includes a shift keylever and shift lock link. The shift lock link is pivotal on the shift keylever and includes an abutment having a recessthat engages a fixed shelf when the shift lock link is actuated.

A control knob has a link extending in opposite directions therefrom. One end of the link is coupled to a switch mechanism in such a manner that rotation of the control knob results in a corresponding movement of the switch mechanism to render the switch circuit closed or open depending on the direction of rotation of the control knob. The other end of the link is coupled to a shift control mechanism that includes a pivotal bellcrank having a release and blocking finger extending therefrom. Therefore, movement of the control knob that'renders the switch open or closed also pivots the bellcrank and bellcrank finger. The bellcrank finger then contacts the link abutment and urges the link to disengage from the fixed shelf.

Accordingly, an object of the present invention is to release the carriage from the upper carriage shift position to the lower carriage shift position when the switch is conditioned to the open state. The lower position of the carriage provides a low silhouette with no portions of the carriage projecting beyond the basic machine lines.

Another object of the present invention is to block the depression of the keylever when the switch is in the open state to prevent actuating of the shift mechanism 2 until the switch is again conditioned in the closed state by the control knobJThis sequence protects the drive motor by preventing the drive motor from being prematurely loaded by the shift mechanism.

Other objects, features, and advantages of the invention will become more apparent from the following description, appended claims, and accompanying draw- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a left elevation view ofa typewriter showing the present invention with the carriage in the lower case shift position.

FIG. 2 is a view similar to FIG. 1 except the keylever is depressed and the carriage is in the upper case shift position.

FIG. 3 is an enlarged elevational view showing of the shift lock link being released by the release mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings and in particular to FIG. 1, a portion of a typewriter 10 is shown. A carriage 12 provides the support for a printing platen 14. Carriage l2, movable from a lower shifted position to an upper shifted position, is shown in the lower shifted position with a typebar 15 impacting on platen 14.

An electrically operative switch 16 is fixed to a frame member 18. A switch bellcrank 20 is pivotally supported about pivot 21 and is coupled to a switch button 22 of switch 16. Switch button 22 is responsive to the pivotal movement of switch bellcrank 20 to condition switch '16 to a closed state or an open state.

A control link 24 has one end 26 pivotally coupled to switch bellcrank 20. Control link 24 extends forward and is pivotally connected to a control knob 28 at a pivot 30 that is spaced from either end of control link 24. Control link 24 extends further forward and terminates in a horizontal flange 32 that extends inward.

Control knob 28 is rotatable about a frame mounted stud 27 and is positioned above control link 24 for easy access by an operator. Control knob 28 includes a projecting abutment 29 and a projecting hub 31. Abutment 29 limits the counterclockwise rotation of the control knob 28 and hub 31 limits the clockwise rotation of the control knob 28. e

A flange 32 of link 24 is pivotally and'slideably coupled to an upstanding arm 34 of a bellcrank 36. Arm 34 includes a slot 38 in which flange 32 is slideably engaged. Bellcrank 36 is pivotally supported on a frame mounted pivot stud 40. Bellcrank 36 further includes a second upstanding arm 42 that terminates in a forward extending finger 44.

A shift keylever 46 is pivotally supported on frame 18 at pivot 47 and biased upward towards a rest position by a spring 48. One end of spring 48 (not shown) is mounted to frame 18 and the other end 53 is attached to an extension 49 of keylever 46. Upward and downward movement of keylever 46 is limited by a pair of integral extending

fingers

50 and 52 that abut a fixed shelf 54 positioned therebetween.

A shift lock link 56 is pivotally supported about a pivot 58 on shift keylever 46. Therefore, any movement of shift keylever 46 results in a corresponding movement of shift lock link 56. A spring 60 connected between extension 62 of keylever 46 and extension 64 of shift lock link 56 biases lock link 56 upward towards a rest position. The rest position of lock link 56 is determined by a lock link lug 57 that abuts a lower edge 59 of keylever 46. Shift lock link 56 further includes a downstanding abutment 66 that lies in the pivot path of bellcrank finger 44 and has a forward edge 68 adjacent an edge 70 of fixed shelf 54. Forward edge 68 of abutment 66 includes a latching recess 72 and a latching surface 74.

During operation, control knob 28 is manually rotated clockwise as viewed in FIG. 2. Link 24 is urged rearward to pivot switch bellcrank 20 rearward until switch button 22 conditions switch 16 to a closed state.

The rearward movement of link 24 also urges bellcrank .36 to pivot counterclockwise. Bellcrank finger 44 is therefore positioned out of the path of abutment 66 to allow for the depression of shift lock link 56.

When a continuous shift operation is desired, shift lock link 56 is depressed. Link abutment 66 is moved downward as surface 68 abuts and slides down along shelf edge 70 as shown in FIG. 1. Abutment 66 continues to slide down along shelf edge 70 until recess 72 is in alignment with shelf edge 70 at which time latching surface 74 slides under and into latching engagement with shelf edge 70 as shown in FIG. 2. At this time, through appropriate linkage (not shown), printing platen 14 is conditioned to an upper carriage shift position.

When it is desired to discontinue the continuous shift operation. as viewed in FIGS. 1 and 3, keylever 46 is depressed. Lock link 56 is urged to move downward until latching surface 74 is disengaged from shelf 70 by the spring 60. Lock link 56 is then biased to pivot upward to its rest position on keylever 46 by the spring 60 and keylever 46 is biased to pivot upward to its rest position on frame 18 by the spring 48. At this time, carriage I2 is conditioned to a lower shift position.

if. however, the power supply of the typewriter is shut off without disengaging the shift mechanism from its upper shift position, the present invention will become effective.

The present invention becomes effective when control knob 28 is manually rotated counterclockwise. Link 24 is urged forward until switch bellcrank 20 moves switch 22 to condition switch 16 to an open state. The forward movement of link 24 also urges bellcrank 36 to pivot clockwise. Bellcrank finger 44 is then pivoted into contact with abutment edge 68 as illustrated in FIG. 3. Continued pivotal movement of bellcrank 36 progressively urges latching surface 74 to disengage from shelf 70. Lock link 56 is then biased to pivot upward to its rest position on keylever 46 and keylever 46 is biased to pivot upward to its rest position on frame 18. Carriage I2 is now conditioned to a lower :shift position and the typewriter is in an inoperative state.

A safeguard against actuation of the shift mechanism when the typewriter is in an inoperative state is provided for by the continued pivotal movement of bellcrank 36. Continued pivotal movement of bellcrank 36 positions bellcrank finger 44 under and into the operative path of lock link abutment 66. Therefore, any downward movement of lock link 56 is blocked until the control knob 28 is rotated clockwise and the con- 4 trol link 24 pivots thc finger 44 from under the abutment 66.

What is claimed is:

l. A release mechanism for a power operated typewriter having a frame, a platen supporting carriage shiftable on the frame between an upper position and a lower position, a keylever operatively connected to the carriage and supported on the frame for movement between a first position with the carriage in the lower position and a second position with the carriage in the upper position, an electrical switch operable between a closed state and an open state for energizing the typewriter, said release mechanism comprising:

locking means supported on the frame for locking the keylever in the second position;

control means supported on the frame for conditioning the electrical switch between the closed state and the open state; and

means movably supported on the frame and responsive to said control means for releasing the keylever from the second position for movement to the first position for locating the carriage in the lower position.

2. A release mechanism as defined in claim 1 wherein said locking means includes a lock link pivotally supported on said keylever, said lock link includes a latching shelf and an abutment, said locking means further includes a shelf fixed to the frame for engagement by said latching shelf when the keylever is locked in the second position, and said responsive means includes a finger for contacting said abutment of said lock link and moving said lock link for releasing said latching shelf from said fixed shelf to release the keylever from the second position for movement to the first position for locating the carriage in the lower position.

3. A release mechanism as defined in claim 2 wherein said lock link includes a lug for engaging the keylever to define an inoperative position of said lock link relative to the keylever, and a spring connected to said lock link for biasing said lock link to said inoperative position when said lock link is released by said finger of said responsive means.

4. A release mechanism as defined in claim 2 wherein said responsive means includes locking means located in the path of said lock link for preventing depression of the keylever when said control means has conditioned the electrical switch in said open state.

5. A release mechanism as defined in claim 4 wherein said blocking means includes a surface on said finger for underlying said abutment of said lock link thereby preventing depression of the keylever.

6. A release mechanism as defined in claim 1 wherein said control means includes an operable member and a control link connected to said operable member, said control link couples said electrical switch to said responsive means for conditioning said electrical switch from the closed state to the open state and for releasing the keylever from the second position for movement to the first position upon actuation of the operable member.

Claims

1. A release mechanism for a power operated typewriter having a frame, a platen supporting carriage shiftable on the frame between an upper position and a lower position, a keylever operatively connected to the carriage and supported on the frame for movement between a first position with the carriage in the lower position and a second position with the carriage in the upper position, an electrical switch operable between a closed state and an open state for energizing the typewriter, said release mechanism comprising: locking means supported on the frame for locking the keylever in the second position; control means supported on the frame for conditioning the electrical switch between the closed state and the open state; and means movably supported on the frame and responsive to said control means for releasing the keylever from the second position for movement to the first position for locating the carriage in the lower position.