US2894613A

US2894613A - Even printing manual typewriter

Info

Publication number: US2894613A
Application number: US560218A
Authority: US
Inventors: Waldemar A Ayres
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-01-19
Filing date: 1956-01-19
Publication date: 1959-07-14
Anticipated expiration: 1976-07-14

Description

July 14, 1959 Filed Jan. 19, 1956 w. A. AYRES EVEN PRINTING MANUAL TYPEWRITER 4 Sheets-Sheet 1 INVENTOR \ahiemzw BY vav w g I ATTO Y5 July 14, 1959 w. A. AYRES 2,894,613

EVEN PRINTING MANUAL TYPEWRITER Filed Jan. 19, 1956 4 Sheets-Sheet 2 0'': J 0 u 61 3w g; 1-1

U g 8 f p; b j

INVENTOR ATTORNEYS July 14, 1959 AYRES I 2,894,613

EVEN PRINTING MANUAL TYPEWRITER Filed Jan. 19, 1956 4 Sheets-Sheet 3 Fig. 4-.

INVENTOR \allem-w Rw BY m m ATTORNEYS July 14, 1959 Filed Jan. 19, 1956 4 Sheets-Sheet 4 INVENTOR "\alem am KKSKQSQ I ATTORNEYS w. A. AYRES 2,894,613

EVEN PRINTING MANUAL TYPEWRITER Unite States My invention relates to improvements in typewriters, and, in particular, provides means in manually powered typewriters causing the printing to have a substantially even blackness because the type bars are operated with substantially uniform force, despite greatly varying force with which the keys may be depressed.

My invention also provides automatic compensation means so that capital letters are imprinted with a slightly greater force, as compared with the same letter in lower case, because of the slightly greater area of the character when written in upper case, and my invention also provides means whereby different characters are imprinted with different typing force, in proportion to the area of each character.

My invention further relates to providing, in manually powered typewriters, means for increasing the typing :force of all characters to obtain an increased number of carbon copies or to decrease the typing force of all char- :acters to obtain quieter operation.

One of the primary disadvantages of manual typewriters, both portable and office machines, as compared with electric typewriters, is that with manual machines the degree of blackness of typed impression varies with the .force with which the key is struck, whereas with the electric machines the force of the typing blow is independent of the force with which the type key is struck by the operator. Consequently, the electric machines provide .a uniformity of blackness or color of typing which is quite impossible with present manual typewriters. Also, the electric typewriters provide a striking force which is generally proportional to the area of the character .on each particular type bar. For example, an m strikes with much more force than a period.

As a further refinement, some electric machines provide for slight increases of force with which the type is driven against the platen when the machine is shifted to write capital letters on the premise that most capitals have slightly greater area than the same letter in the lower case.

A still further refinement on some electric typewriters is that the force of the typing blow may be adjusted by the operator to be increased when additional carbon copies are desired, or to be decreased when these are not necessary and it is desired to operate the machine more quietly.

A principal purpose of this invention is to provide new principles and mechanisms, applicable to manually powered tyewriters, both portable and upright office machines, which will provide substantial uniformity of the typed impression regardless of major variations of force with which the operator may strike the keys.

Another purpose of the invention is to provide for manually powered typewriters mechanical means whereby the force of the printing blow may be adjusted differently for different characters so that the force of the blow is generally proportional to the area of the character being typed. For example, the m will be driven with considerably more force than the period, so that Patented July 14, 1959 these will make a printed impression of substantially equal blackness.

Another object of the invention will be to provide means for manual machines so that when capital letters are being typed the force of the printing blow will automatically be increased slightly to compenate for the slight increase of character area, for example, capital M as compared with lower case m, to provide substantially the same blackness of printing as when this same letter is typed in lower case.

Another object of the invention is to provide for manually powered typewriters, means whereby the striking force of all the print bars can be adjusted by the operator to provide for an increased number of carbon copies, or for greater blackness of impression, or, instead, the printing force may be adjusted to a lesser amount-to enable the machine to operate more quietly.

Other objects and advantages of the invention will become evident during the course of the following descriptions.

The basic principles whereby these objects may be obtained are as follows:

(1) Disconnect the usual present linkage between the key bar and the type bar.

(2) Provide spring means between these two elements.

(3) Provide a mechanism so that the downward movement of the key bar stores energy in the spring linkage while the type bar is restrained from moving toward the platen.

(4) Provide for the automatic release of the restraining mechanism substantially at the bottom of the key bar stroke and provide that the energy stored in the spring is then released to provide the driving force for the printing action of the type bar.

In this way, the varying force with which an operator may depress a key will have no efiect upon the force with which the type bar is operated.

To test the soundness of these principles and to develop thoroughly practical and usable designs for mechanisms, parts were obtained from Underwood and Royal typewriters and these parts were built into operating models with such modifications that the above listed principles were successfully embodied. The printing by these operating models of the modified type bar and key bar actions was tested in a variety of ways and all were successful. In the first place, the key bars were depressed with forces which varied from a very sharp stroke to pressures so light and slowly applied that they did not -produce any visible imprint when a mechanical typewriter, which was used as a comparison in these tests, was operated in the same manner. Nevertheless, in all cases, the modified key bar actions printed with uniform results, very superior to anything obtainable by any other manually powered typewriter known to us.

In addition, such tests were run with an original .and one carbon copy; an original and two carbon copies; and an original plus sixcarbon copies. In the last case, the test sheets also carried test typing done on a comparison manually powered typewriter and the imprints made by this comparison machine varied'from very black toan imprint which was barely discernible even under good seeing conditions. The operation of the modified Underwood and Royal mechanism-s was made the same in regard to variations of forces with which the key bar was depressed. In all cases, the modified mechanism produced imprints of equal blackness as compared with the manually powered machine where the blackness of printing ranged from very black to a barely detectable imprint.

In regard to the carbon copies, examination of results showed that the uniformity of printing force carried through all the carbon copies. 'Whether key bars had been depressed sharply or slowly or lightly, the carbon .3 copies of the resulting imprints were of uniform blackness on all of each page, although, of course, each successive carbon copy was progressively fainter. In this way, it was proved that with mechanisms embodying these principles all the characters on any given page of the carbon copies will have equal legibility, as contrasted with carbon copies made on present manually powered typewriters where characters which have been imprinted lightly on the first sheet may disappear altogether in the later pages where other characters are very black, thus producing a great variation of printing blackness and major loss of legibility in many instances.

Considering how important carbon copies are in relation to the increasing complexity of business and government activities, many of which are routinely handled on the basis of information conveyed by the third, or fourth, or fifth carbon copy, it is apparent that these principles, which will very importantly improve the legibility of carbon copies, will be of substantially high value to industry, government and numerous other fields which can advantageously make use of these benefits.

In the accompanying drawings, forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

Figure l is a side elevation of the key bar and type bar mechanism of the Underwood type of mechanism, modified to embody principles of my invention,

Figure 2 is a side elevation of one shift key and the mechanism it operates to automatically provide an increase of the printing force for capitalization, in conjunction with means for adjusting the printing force for all characters,

Figure 3 shows a comparison between the floating links used for letters as contrasted with those used for numerals and special characters in the mechanism shown in Figure 2,

Figure 4 is a side elevation of the principles of my invention applied to the type of mechanism typically employed in a Royal typewriter,

Figure 5 is a side elevation of the type of key and type bar mechanism used in the Olympia portable typewriter,

Figure 6 is a side elevation of the type of key and type bar mechanism used in the Olympia modified to embody the principles of my invention, and

Figure 7 is a sectional view showing an adjustable sliding spring control mounted on the key bar.

Referring to the drawings:

In Figure 1, l is a key bar extending from the key top 2 toward the right through the combined comb and stops 3, and 3A and 3B, and extending further toward the right where it dips downwardly to pass below the pivot position 5 of the bellcrank 6, and extending still further toward the right ending at the pivot 7. The key bar 1 is continuously pulled in the upward direction by the return spring 8 and is held against the upper stop of the comb 3. 9 is a spring member which may be of many different types. One of these may be a spring bent into the approximate shape of a hairpin having substantially

parallel arms

9a and 9b, and secured by any appropriate means, such as a suitably designed rivet, at the ends 10 to the side of key bar 1. The under surfaces of spring 9 are spaced outwardly from the adjacent surface of key bar 1 by a sufficient distance to provide close operating clearance for the adjustable slider 11. This slider, as shown in Figure 7, is a bent piece of thin metal, extending across the near face of key bar 1, across its upper and lower edges, and extends downwardly and upwardly on the far side of key bar 1, pressing lightly against the surface of key bar 1 to provide sufiicient friction so that when the slider 11 is adjusted by being moved to any given position the friction between it and key bar 1 will cause it to stay there. This slider 111 has a portion at the left bent toward the reader and extends across 9a, the upper member of spring 9,

and acts to prevent the movement of 9a in the upward direction. The adjustment of this slider llll consequently provides varying stiffness of action of spring 9. The crook of spring 9 carries a stud 112 which is suitably secured to spring 9 by soldering, brazing, welding, riveting or other suitable means. This stud 112 extends between the arms of the fork 13 of the bellcrank 6. The upper end of bellcrank 6 carries a stud 14 which extends through slot 15 of the type bar 16 which is pivoted at 17 and carries the type head 18 which when operated strikes against the platen 19. 2% is a swinging stop member pivoted at 2.1 on key bar It. It is pulled in a clock-wise direction by spring 22 until its abutment, provided by the bent section 23 which extends downwardly and across the lower edge of key bar ll, contacts the under edge of key bar 1. The left vertical edge of movable stop 2% acts as a restraining means for the right hand edge of the downward extension 24 of the bellcrank 6, as will be described later.

The operation of the mechanism, as shown in Figure l, is as follows:

When the operator presses downwardly on key top 2, key bar 1 moves in a downward direction in the comb and stops 3 and moves counter clockwise about the pivot 7. The spring 9, due to its anchorage at 10, tends to move with the key bar 1, but, because of its engagement through stud 12 with the fork 13 of the bellcrank 6, as soon as bellcrank 5 starts to move in a counter clockwise direction it abuts against the left vertical face of movable stop 20. As the key bar 1 moves farther downward, its motion stores additional energy in spring 9 because of the increasing deflection imparted to that spring. As the key bar 1 moves downwardly, it carries with it the movable stop 26*, because the portion 23 which extends across the lower edge is carried forcibly downward by the movement of key bar 1. This action continues until the upper left corner of movable stop 20 is just a little lower than the lower tip of portion 24 of bellcrank 6. Then, bellcrank 6 is released and the stored energy in spring 9 forcibly drives the fork l3 downward and, thereby, rotates bellcrank 6 forcibly in a counter clockwise direction. Through the engagement of stud 14, this drives the type bar 16 forcibly in a clockwise direction, carrying type head 18 forcibily against the platen 19 to print the character selected. It is apparent that the energy with which the type head 18 is driven against the platen is due entirely to the amount of energy stored in the spring 9, and the amount of this energy is entirely dependent upon the downward position of key bar 1 and not at all upon the rate at which the key bar was forced downward, nor upon the force with which it was pressed downward. it is apparent, therefore, that the printing force of type bar 16, by the principles embodied in this mechanism, has been made a uniform quantity regardless of greatly varying forces with which key bar It may be depressed.

When the operator takes her finger of the key top 2, and the key bar moves upward under the influence of the return spring 8, the spring 9 acts to drive the bellcrank 6 in a clockwise direction and, thereby, returns type bar 16 to its initial home position. As the key bar 1 moves upward, and as the bellcrank 6 moves clockwise, the movable stop 29 pivots counter clockwise about the pivot 21, allowing the bellcrank 6 to rotate in a clockwise direction. When the portion 24 of bellcrank 6 passes so that it is at the left of the vertical face of movable stop 20, then the spring 22 drives the movable stop 24 in a clockwise direction back to its initial position where the stop 23 presses against the under edge of key bar 1. In this way, the mechanism is automatically relatched, ready for the next cycle of operation.

The means for adjustment of the printing force for proportioning it to the area of the character of a particular key bar (for example, to provide compensation for the difference in area between two such characters as m and the period) is slider 11 which may be conveni- :ently adjusted at the factory or by the service man, after the typewriter has been assembled, to provide each key bar with its own individual adjustment. Moving the slider to the right increases the printing force, while moving it to the left decreases the printing force. This slider 11 has been very carefully designed to provide a lowfcost, easily-installed element which may be readily adjusted from the bottom of the typewriter with as simple a tool as a screw driver. Also, the slider 11 is so designed that the forces acting upon it will not make it creep in one direction or the other and get out of adjustment.

In Figure 2, a side elevation of one shift key and the mechanism it operates to automatically provide an increase in the printing force for capitalization, the shift key 25 extends toward the right, through the combined comb and stops 3, and is connected by an appropriate, conventional linkage, represented by 26, to operate conventional shift mechanism, and is pulled continuously in an upward direction by the return spring 27, and carries the movable pivot 28, and is pivoted to the frame of the typewriter at 29. Key bar 1 is shown in fragmentary form, carried by the pivot 7 and pulled upwardly by the return spring 8. Pivot 7 is mounted on the floating link 30, the bottom end of which is slotted to receive movable pivot 28 and the top end of which is pivoted at 31. Pivot 31 is carried by the lower end of the adjustment lever 32, which is pivoted to the frame of the typewriter at 3'3, and carries a knob 34 to be grasped conveniently by the operator. This adjustment lever may be pointed, as at 35, and may operate relative to a calibrated scale 36, as an aid in adjusting the adjustment lever. This lever is to enable the operator to adjust for increasing printing force for all characters to obtain increased blackness of printing or an increased number of legible carbon copies, or, conversely, to decrease the typing force of all characters when increased blackness or number of carbon copies is not necessary and when increased quietness of operation is preferred.

The operation is as follows:

It was found by experiment that moving the pivot point 7 in Figure 1 provided variations in the force with which the type head 18 imprinted a character at platen 19. The pivot position 7 may be moved in either a vertical direction or a horizontal direction to effect this variation. Movement in the horizontal direction will be described as illustrative of means for obtaining the desired action in connection with capitalization, as well as variation of printing force for all characters. Moving pivot 7 toward the right decreases the printing force of type head 18, whereas moving pivot 7 to the left increases the printing force of type head 18. The limit of movement to the left of pivot 7 is reached when the gap between the left vertical surface of movable stop 20 and the portion 24 of bellcrank 6 is entirely closed. It is intended that the average printing force for lower case will be provided by a position of pivot 7 such that there will be a small gap between the left face of movable stop 20 and the right face of portion 24 of bellcrank 6.

Downward movement of shift bar 25, which moves counterclockwise about pivot 29, will move pivot 28 toward the left. This will move the lower end of floating link 39 toward the left by a corresponding amount. The upper end of floating link 30, pivoted at 31, will not move toward the left, with the result that pivot 7, intermediate between 31 and 28, will move toward the left a proportionate amount. The amount of movement is chosen by dimensioning the parts involved and the pivot positions involved, so that the pivot 7 is moved an amount which causes the depression of letter key bars amount substantially proportional to the increased area 6 of theaverage capital letter as compared with the average lower case letter. a

When the operator takes her finger oif shift key 25, or unlocks it if she has previously used the shift lock, the shift key 25 will move upward under the influence of return spring 27 until shift key 25 resumes its initial home position against stop 3. This action will move pivot 28 toward the right to its initial home position and will restore the floating link 30 and the intermediate pivot 7 to their home positions.

Some of the key bars control numerals and special characters as contrasted with letters of the alphabet. For such characters, We ordinarily do not want additional printing force when the shift is operated and, therefore, as a further refinement, may wish to provide means so that the shifting operation previously described applies only to key bars controlling letters of the alphabet. This may be accomplished by providing two kinds of floating links as shown in Figure 3. The floating link on the left, 37, is the type employed for letters of the alphabet where we want the shifting action described above to result. The special type of link 38 is nlsed for numerals and other characters where we do not Want the operation of the shift lever 25 to increase the printing force. The design Worked out aims at accomplishing this differentiation in a manner which is simple, inexpensive to manufacture, and reliable in operation. The pivot 28 in Figure 2 extends across the typewriter and engages the floating links for all the type bars, except the links 38, where it passes underneath these, as shown in Figure 3. When pivot 28 moves toward the left, it will carry the bottom ends of all the links 37 toward the left, but not the links 38. The restraining bar 39 extends through all of the links 38 and is mounted rigidly to the frame of the typewriter. The reason for the arcuate shape of the vertical slot 40, which engages bar 39, will be explained later.

The operation of the manual adjustment means whereby the operator may adjust the printing force of all the typewriter printing bars for increased numbers of legible carbon copies, etc. is as follows:

The operator can move the adjustment lever 32 either to the right or left relative to the calibrated scale 36. Moving the lever toward the right will increase the typing force whereas moving it toward the left will decrease the typing force. The lever pivots about pivot 33, causing the pivot 31 to move accordingly. 31 is a bar which extends across the typewriter and engages the upper end of all the floating

links

37 and 38. Movement of the adjusting lever 32 clockwise, toward the right, results in movement of pivot 31 toward the left. This carries with it the upper ends of all the floating

links

37 and 38 toward the left. This action carries the key bar pivots 7 proportionally toward the left and, thereby, increases the typing force for all characters. Conversely, moving the adjustment lever 32 counter clockwise, toward the left, causes the pivot 31 to move toward the right and, thereby, moves pivot 7 toward the right a proportionate amount. This action decreases the printing force for all the characters. It is apparent that the floating links 37 are a very simple form of differential, enabling independent motions to be entered into the system by independently moving the two ends of the links, whereby the pivots 7 are moved a proportionate amount which is equal to the algebraic sum of the movements of

pivots

31 and 28.

Because the bottom portions of links 38 do not engage pivot bar 28, means are provided for causing the floating links 38 to swing about the center of pivot 28 when pivot 31 is moved either to the right or left. This requirement is fulfilled by providing the vertical slot 40 and making this a curved slot which is an arc of a circle, having its center in the center of pivot 28 when in its home position, as shown in Figure 3. It is apparent that any movement of pivot 31 to the right or left will 'the same as described in connection with Figure l.

.pivoted to the frame of the typewriter at 51.

floating links 38 and the print bars associated with them by exactly the same amount as links 37 and the print bars associated with them, but operation of the shift key will not move links 33.

In Figure 4, a side elevation of the principles of my invention applied to the type of mechanism typically employed in a Royal typewriter, 41 is a key bar extending toward the right through the combined comb and stops 3, 3A and 3B, and extending directly toward the right, ending at the pivot 42. At 43 a hairpin type spring, similar to 9, 9a and 9b as described in connection with Figure 1, is secured to key bar 41. The stiflness of action of spring Q is controlled by a slider 11, Stud 12, carried by the crook of spring 9, as described m Figure l, in this case is pivoted on floating link 44 which has its upper end pivoted at 45 to arm 45' of the bellcrank 46. Bellcrank 46 is pivoted to the frame of the typewriter at 47. A movable stop 20 is provided, which is of the same type as that shown and described in con nection with Figure l. The upper end of bellcrank 4-6 engages and is connected to one end of the floating link 48, the other end of which engages and is connected to the lower end of type bar 39 at 50. The type bar 49 is 52 is a clip secured to the floating link 48 and carries one end of return spring 53. The other end of the return spring 53 is mounted at 54 on floating link 55 between its

pivots

56 and 57. 58, when used, represents the special floating links for numerals and special characters for which operation of the shift key is not to provide increased printing force and these may be of the same design as links 38 shown in Figure 3. Similarly, links 55 may be of the same design as links 37 shown in Figure 3. The adjustment lever 59 may be of the same design as 32 shown in Figure 2. The lever 69 is pivoted to the frame of the typewriter at 61 and carries a pivot engaging all the lower ends of the floating links in the same manner as pivot 28, shown and described in Figure 2. The lower end of lever 60 is pivotally connected with a link 64 which may be any appropriate conventional linkage, connecting the usual shifting n eans in a typewriter with the lever 69. The linkage is such that the lower end of the lever 60 is moved toward the right, as shown, when a shift key of the typewriter is operated.

The operation of the mechanism is as follows:

When key bar 41 is moved downwardly the spring 9 is deflected because it is connected through floating link 44 with the bellcrank 46. Belicrank do is prevented from rotating counter clockwise because its lower portion abuts against the left vertical face of movable stop 2 3". This action continues until key bar 41 moves down far enough so that the upper left corner of movable stop 26 is just below the lower end of bellcrank d6, whereupon bellcrank 46 is released and the stored energy in spring 9 forcibly drives bellcrank 46 in a counter clockwise direction. This causes connecting link n: to rotate type bar 49 forcibly up against the plate 19. On the return stroke, the key bar 41 is pulled upward by the return spring 8, and the return spring 53 (as well as spring 9) returns the type bar 49 to its initial home position. The fact that type bar 49 is returned to its home position by the action of both spring 53 and spring 9 indicates that one or the other might be omitted or modified where desired. For example, a coil spring might be substituted in the location of the floating link 44 and used instead of spring 9 with its adjustment slider Iii, as will be described in Figure 5. Also, for example, the return similar to that described in Figure 2. However, the

mechanism shown in Figure 4 is provided to illustrate another set of principles which may be used in connection with capitalization and adjustment of typing force for all characters.

The action of these two adjustments is as follows:

It is apparent that when key bar 41 is operated and when bellcrank 46 moves counterclockwise, the force with which the type bar 4-9 is driven against the platen 19 is reduced by the stretching of spring 53 during the course of this action. This may be'stated as: the striking force of the type head is proportional to the energy stored in spring 9, minus the energy required to stretch spring 53. It is clear that variations of printing force may be accomplished by varying the tension at which spring 53 is stretched as type bar 49 moves toward platen if. This may be accomplished by moving the anchorage point of the right hand end of spring 53 at the pivot position 54, which corresponds to the pivot 7 of the floating links shown and described in Figure 2.

When the shift key is depressed the linkage connected with it pushes link 64 toward the right and rotates lever 61) counterclockwise about the pivot 61. This action moves all of the bottom ends of the floating links 55 of the alphabetic characters toward the left, but does not move the bottom ends of the floating links 58 toward the left, in the same manner as was previously described and shown in connection with the floating links of Figure 2. Pivot positions 54, which correspond to the pivot positoins 7 of Figure 2, move toward the left in the same manner as previously described. This reduces the amount of tension to which spring 53 is subjected when type bar 69 moves toward the platen l9 and, thereby, subtracts less energy from the energy being supplied by spring 9 and, therefore, results in an increase in the typing force of type bar 49 against platen 1%.

Movement of the adjustment lever 59, clockwise or counterclockwise, about the pivot 6-3 causes the pivot 56, which corresponds to the pivot 31 in Figure 2, to move the upper ends of the floating links toward the right or left. This results in proportionate movements of the pivots 54, which correspond to pivot 7 of Figure 2. These motions increase or decrease the tension of springs 53 and hence correspondingly decrease or increase the net printing force with which type bars 49 strike against the platen.

In Figure 5 a side elevation is shown of the key bar and type bar mechanism such as is used by the Olympia typewriter, built in Germany and sold widely in the United States. 64 is the key bar pivoted at 65. The tension of the return spring 66 normally holds key bar 64 against the stop 67. Downward movement of the key bar64 carries with it the link 68 which pulls down the left end of lever 6? against the tension of spring 74 This causes lever 69 to rotate counterclockwise around pivot 71 which causes the link 72 to rotate type bar 73 clockwise about its pivot 74. When the operator releases key bar 64, the spring 7t) and the spring 66 cause the mechanism to return to its home position.

Figure 6 shows one method whereby the principles of this invention may be applied to the typewriter mechanism shown in Figure 5. Key bar 64 has pivotally mounted on it at 75 a movable stop 76 which includes a vertical face portion 77 at the right, and a bent portion providing an abutment 73 which extends across the lower edge of key bar 64, and a spring member 7h which presses against the edge of key bar 64, as shown. This spring 79 acts to rotate the movable stop 76 in a counter clockwise direction until the abutment 78 contacts the lower edge of the key bar 64. Key bar 64 also has a lower extension bent toward the reader at 80, which has a clearance hole through which extends an adjustment screw 81, the upper end of which is threaded into the spring 82. The upper end of 32 is carried by the hole 83 in the lever 84. S5 is a stud riveted to the lever 84 and cooperates'withthe fork of bellcrank 86. 87 is a return spring engaging the lever 84 and is anchored on the floating link 88. Floating link 88 is connected at its two ends 89 and 90 with conventional linkages (not shown) to the shift mechanism, in one case, and to an adjustable lever, corresponding to lever 59 in Figure 4 or lever 32 in Figure 2. In the same manner as previously described, link 88 constitutes a floating link type of differential. 84 is pivoted at 91 to the frame of the typewriter and its right end is connected by link 92 to the type bar 93 which is pivoted to the frame of the typewriter at 94.

The action of the mechanism is as follows:

When the operator presses key bar 64 downwardly the stretching of spring 82 tends to carry with it the left end of lever 84. However, stud 85, cooperating with the fork of bellcrank 86, is prevented from moving downward because bellcrank 86 cannot rotate clockwise because its lower portion is stopped by the portion 77 of the movable stop 76. As the downward movement of the key bar 64 continues, the spring 82 is increasingly stretched until the upper tip of portion 77 of movable stop 76 is just below the lower portion of bellcrank 86. Then, bellcrank 86 is released to rotate clockwise and the stored energy in spring 82 forcibly pulls dovmward on the left end of lever 84 which in turn pulls the floating link 92 toward the left and this in turn drives the type bar 93 forcibly up against the platen.

When the operator removes her finger from key bar 64, the return spring 87, which has been stretched by the downward movement of the left end of lever 84, now contracts, pulling up the left end of lever 84 which returns the type bar 93 to its initial position. This action also lifts spring 82 and it moves and contracts also, lifting the key bar 64 which is further lifted by the action of the return spring 66.

In the same manner as described in connection with Figure 4, the net printing force of the system may be ad justed by increasing or decreasing the extent to which the spring 87 will be stretched during the printing operation. Consequently, any appropriate linkage of the shifting mechanism of the typewriter may be used to move one end of floating link 88 downwardly when the shift key is operated, thereby increasing the printing force of type bar 93. Also, the other end of floating link 88 may be connected by any appropriate linkage to a lever such as shown and described as lever 59 in Figure 4 or lever 32 in Figure 2. Moving this lever in one direction will cause one end of the floating link 88 to move downwardly which will increase the printing force of type bar 93, whereas moving in the opposite direction will decrease the printing force.

It should be borne in mind that the scope of this invention is not limited to the forms shown and described but it specifically includes other types of levers, locations of parts, and designs of components which may embody the basic principles of this invention and accomplish the objects stated and illustrated by the examples given with out departing from the spirit of this invention.

Thus, having described my invention, I claim:

1. In a manually powered printing device, a character selecting means and a printing means, mechanism operatively connecting said character selecting and printing means for operation of the latter by actuation of the character selecting means, said mechanism including an energy storing means connected to said character selecting means to operate said printing means subsequent to the initial actuation of said character selecting means, and restraining means mounted on said character selecting means and in engagement with said printing means at the initiation of the actuation of said characterselecting means to prevent operation of said printing means, said restraining means being disengaged from said printing means subsequent to the initial actuation of the character selecting means.

2. A manually powered printing device in accordance with claim 1 wherein adjustable control means is connected to said energy storing means for controlling said energy storing means so that the force with which the printing means is operated is substantially proportional to the area of the character to be printed.

3. A manually powered printing device in accordance with claim 1 wherein said restraining means includes an element pivotally mounted at one end on said character selecting means and at its other end engaging with said mechanism for restraining said mechanism from operation until subsequent to the initial actuation of said character selecting means.

4. A manually powered printing device in accordance with claim 1 wherein said mechanism includes a linkage provided with a projection extending downwardly adjacent said character selecting means, and said restraining means includes an elongated rigid element pivotally mounted at one end on said character selecting means and at its other end in engagement with said projection for restraining said mechanism from operation until subsequent to the initial actuation of said character selecting means.

5. In a manually powered printing device, key bars and type bars and restraining mechanism operatively associated with said bars, energy storing means operatively associated with said bars and said restraining mechanism, shift means and further means connected with said shift means and certain of said key bars for automatically modifying the force with which the corresponding type bars are operated.

6. In a manually powered printing device, character selecting means, energy storing means operated by said character selecting means, restraining means adapted to be released by said character selecting means after it has been operated a predetermined distance, printing means operatively associated with said energy storing means and operated thereby when released, shift means, and

' means operatively associated with said shift means whereby the printing force is increased for capital letters.

7. In a manually powered printing device, character selecting means, printing means, energy storing means connecting said character selecting means and said printing means, typing force control means cooperatively associated with said printing means, shift means, and means whereby operation of either said shift means or said control means will modify the force with which characters are printed.

8. A manually powered printing device in accordance with claim 7 wherein means is provided whereby the printing force for certain preselected characters only is modified when the shift means is operated.

9. In a mechanism of the ciass described, character selecting means, printing means, energy storing means and restraining means operatively associated with said character selecting means for operating said printing means, and control means whereby the character selecting means may be moved to modify the force actuating the printing means.

10. In a manually powered printing device, character selecting means, printing means, energy storing means and restraining means operatively associated with said character selecting means for operating said print-ing means, a return spring, the action of said return spring may be controlled to modify the force with which characters are printed.

11. In a manually powered printing device, character selecting means, printing means, energy storing means and restraining means operatively associated with said character selecting means for operating said printing means, a spring operatively associated with said printing means, two controls, and means combining two independent control motions for moving the anchorage position of said spring to modify the force with which characters may be printed.

12. In a typewriter, character selecting means, manual- 'lll lypowered printing means, mechanism operatively connecting said character selecting means and said manually powered printing means, energy storing means and restraining means operatively associated with said character selecting means and said manually powered printenergy storing means adapted to provide printing force substantially proportional to the area of the character to be printed, shift means, means operatively associated with said shift means and said printing means to modify the force with which certain characters are printed, and adjustable control means for all characters operatively associated With said printing means adapted to modify the force with which all characters may be printed.

14. In a printing device, the combination of character selecting means and manually powered printing means operatively associated with each other, and separate energy storing means and separate restraining means for each character selection means and printing means adapted to prevent movement of said printing means until a predetermined amount of energy has been stored in said energy storing means whereby selected characters will be imprinted with uniform intensity regardless of major non-uniformity of force of operation of the character selection means, and infinitely adjustable means operatively associated with each energy storing means to predetermine the amount of energy to be stored before printing action takes place whereby the printing impact for different characters may be made proportional to their different character areas.

15. In a printing device, the combination of character selecting means and manually powered printing means operatively associated with each other, and separate energy storing means and separate restraining means for each character selection means and printing means adapted to prevent movement of said printing means until a predetermined amount of energy has been stored in said energ storing means whereby selected characters will be imprinted with uniform intensity regardless of major nonuniformity of force of operation of the character selection means, and shift means, and further means operatively associated with said shift means and said printing means whereby the printing force for upper case characters may be automatically increased to maintain a printing impact substantially proportional to their increased character areas.

16. In a printing device in accordance with claim 15, including means for automatically differentiating between upper case characters whereby the printing impact is increased for certain preselected upper case characters but not for others.

17. In a printing device, the combination of character selecting means and manually powered printing means operatively associated with each other, and separate energy storing means and separate restraining means for each character selection means and printing means adapted to prevent movement of said printing means until a predetermined amount of energy has been stored in said energy storing means whereby selected characters will be imprinted with uniform intensity regardless of major non-uniformity of force of operation of the character selection means, and adjustable means for presetting each individual energy storing means to deliver a printing impact substantially proportional to the areas of lower 12 case characters, shift' means, and means associated with said shift means and said printing means whereby the printing force may be automatically increased to maintain impact substantially in proportion to the increased character areas of upper case characters.

18. In a printing device, the combination of character selecting means and manually powered printing-means operatively associated with each other, and separate energy storing means and separate restraining means for each character selection means and printing means adapted to prevent movement of said printing means until a predetermined amount of energy has been stored in said energy storing means whereby selected characters will be imprinted with uniform-intensity regardless of major non-uniformity of force of operation of the character selection means, and adjustable means for presetting each individual energy storing means to deliver a printing impact substantially proportional to the areas of iower case characters, and manual control means operatively associated with said energy storing means and said print ing means whereby the printing impact of all characters may be modified.

19. In a printing device, the combination of character selecting means and manually powered printing means operatively associated with each other, and separate energy storing means and separate restraining means for each character selection means and printing means adapted to prevent movement of said printing means until a predetermined amount of energy has been stored in said energy storing means whereby selected characters will be imprinted with uniform density regardless of major non-uniformity of force of operation of the character selection means, and including shift means, further means operatively associated with said shift means and said printing means whereby the printing force for upper case characters may be automatically increased to main tain a printing impact substantially proportional to their average increased character areas, and control means operatively associated with said energy storing means and said printing means whereby the printing impact of all characters may be modified.

20. In a printing device, the combination of character selecting means and manually powered printing means operatively associated with each other, and separate energy storing means and separate restraining means for each character selection means and printing means adapted to prevent movement of said printing means until a predetermined amount of energy has been stored in said energy storing means whereby selected characters will be imprinted with uniform intensity regardless of major non-uniformity of force of operation of the character selection means, and including adjustable means operatively associated with each energy storing means whereby printing impact will be substantially proportional to character area for lower case characters, shift means, further means operatively associated with said shift means and said printing means whereby the printing impact of upper case characters may be increased, and control means whereby the printing impact of all characters may be modified.

References Cited in the file of this patent UNITED STATES PATENTS 886,447 Wahl May 5, 1908 970,250 Mallman Sept. 13, 1910 1,173,321 Steiner Feb. 29, 1916 2,206,624 Bates et a1. July 2, 1940 2,344,167 Pitrnan Mar. 14, 1944 2,403,270 Eddy July 2, 1946 2,697,502 Becker Dec. 21, 1954