US2750022A

US2750022A - Type bar impact control

Info

Publication number: US2750022A
Application number: US463432A
Authority: US
Inventors: William J Long
Original assignee: International Business Machines Corp
Current assignee: International Business Machines Corp
Priority date: 1954-10-20
Filing date: 1954-10-20
Publication date: 1956-06-12
Anticipated expiration: 1973-06-12
Also published as: GB784561A; DE1073006B

Description

June 12, 1956 w. J. LONG 2,750,022

TYPE BAR IMPACT CONTROL Filed Oct. 20, 1954 s Sheets-Sheet 1 T FIG. 1

RUBBER BINDING ST-RIP 1F- INVENTOR.

"WILLIAM J. LONG w m M4 5 June 12, 1956 w. J. LONG TYPE BAR IMPACT CONTROL 5 Sheets-Sheet 2 Filed Oct. 20, 1954 INVENTOR. WILL] M J. LONG k) (wMr June 12, 1956 w. J. LONG 2,750,022

TYPE BAR IMPACT CONTROL Filed Oct. 20, 1954 3 Sheets-Sheet s FIG. 6

LIJLLI E2 0 INVENTOR. 8 WILLIAM J LONG mum;

Patented June 12, 1956 TYPE BAR IMPACT CONTROL William J. Long, Poughkeepsie, N. Y., assignor to International Business Machines Corporation, New York, N. Y., a corporation of New York Application ctober'20, 1954, Serial No. 463,432

7 Claims. (Cl. 19717) This invention relates to typewriting mechanisms and more particularly to an improved upper and lower case selection and impression control for a typewriter.

The typewriter art has always been faced with the problem of producing equal color density for upper and lower case characters, since generally, the upper case character has a larger area (and hence for any given force, a lesser pressure per square inch of printing area) than the lower case character carried by the same type bar. As a result of this difference in pressure, the color density of the upper case character usually will be less than that of the lower case character for any one impression control setting. Industry, however, demands that all type characters be of uniform color density, and accordingly, it is a first object of this invention to provide an improved upper and lower case impression control for a typewriter.

Another uniform printing problem is presented by the typing conditions. For example, by the ribbon; that is, whether it be cloth or carbon when used in conjunction with various types of printing paper, or if no ribbon at all is used, as in stencil work. More specifically, it is generally understood in the typewriter art, that a range of imprint pressure-sometimes called group control--.-is required for each set of printing conditions in order to govern the required color density or uniform depth of paper plate penetration for each character stenciled.

For any one set of typing conditions, the group control may be set selectively at maximum imprint pressure for dark typing or deep penetration, 'or at some position in the group control range giving a lesser imprint pressure for a relatively lighter typing or penetration. However, the range of imprint pressure or group control for one set of typing conditions may be entirely diiferent from the group control range required for another set of printing conditions. A specific example of "condition change (a term hereinafter used in this specification to denote a complete change of typing conditions requiring a different range of group control) may be found in the light range of imprint pressure required for stenciling paper plates (as used for example, in duplicating processes) wherein a delicate uniform paper penetration is required for a single sheet, in contrast with the heavyrange of impression control required when either fabric or carbon ribbon is used in combination with conventional letter writing paper wherein four or more carbon copies may be required.

Because of this great variance in range of group control, it has been necessary, in order to provide the degree of perfection that industry demands, to equip some business ofiices with two typewriters; each adjusted to handle respectively one class of printing conditions.

In order to avoid this expensive machine duplication, it is an object of this invention to provide an improved typewriter impression control which is operable to handle two entirely different classes of printing conditions, or condition changes.

It is a further object of this invention to provide an improved impression control mechanism wherein, an upper and a lower case control is provided respectively for each type bar so that it may operate properly for tw sets of condition change."

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 is a side elevation of one type bar drive mechanism positioned for operation with an improved impression control mechanism.

Fig. 2 is a top view of the improved impression control mechanism. I

Fig. 3 is a side elevation of the impression control mechanism shown operatively connected to a basket shift mechanism.

Fig. 4 is a side elevation taken through plane 44 of Fig. 2, while Fig. 5 is a front elevation taken through plane 5-5 of Fig. 4.

Fig. 6 is a perspective view of the improved impression control bar used in conjunction with my improved control mechanism.

Briefly, this invention relates to an improved impression control mechanism wherein a plurality of rows of adjustable stops are circumferentially spaced about the periphselectively to co-act with a type bar drive mechanism to regulate its degree of impression control.

As an introduction to the subject matter of this inven tion, reference is made to United States Patent No. 2,5l7,989-Dodge-assigned to the same assignee as that 'of the present invention wherein a complete description of the basket shift mechanism for upper and lower case control of an IBM typewriter is shown.

The aforementioned United States patent describes in detail the shift mechanism shown in Fig. 3 of the subject application, and accordingly, it is felt that a brief statement regarding its operation will sufiice for the purpose of this description. Specifically, a power roll 2 is motor driven in a clockwise direction as viewed in Fig. 3, while a shift cam unit 4 is pivotally supported in the typewriter response to depression of the shift lever 6, and particularly through the push of link 7, shift cam 8 is moved.

into operative engagement with the power roll 2 for one half revolution thereby causing the cam unit 4 to .be driven about its bearing support 10 to exert a pull on link 12 that rocks lever 14 clockwise about its pivot 16.

Conjointly, with the actuation of shift cam 8 through the depression of the shift lever 6, an extension 18 of the shift lever 6, which incidentally, is pivotably supported by stud 20, lifts the trip link 22 thereby conditioning a yoke 24 so that one of its legs 26 is positioned for engagement with stud 28 extending laterally from a shift plate 30 which, in turn, is pivotally supported on cross shaft 32.

concomitantly, with the conditioning of yoke 24, the shift link 12, in rocking lever 14 clockwise about pivot 16, causes yoke leg 26 to push on stud 28 fl'lereby rocking shift plate 30 counterclockwise about its supporting cross shaft 32. Through this operation, the connecting arm 34 from engagement with the shift cam 8 which then makes another half revolution, again exerting a pull on the shift link 12 to rock lever 14 clockwise about pivot 16; but conjointly, with the actuation of the shift cam, the trip link 22 will have positioned the yoke 24 so that its leg 40 will engage a stud 42 whereby, in response to the rocking of the lever 14, shift plate 30 will be rotated clockwise about cross shaft 32 thereby restoring basket 38 to its normal or lower case position.

As heretofore mentioned, a complete description of this shift operation is given in the United States Patent 2,517,989; but for the purposes of laying the ground work for the subject invention, it seems sufficient to say that in response to depression of the shift key lever 6, the shift plate 30 is rotated counterclockwise about shaft 32 while upon release of the shift key lever 6, the shift plate 30 is rocked clockwise from its upper case position back to the lower case position shown in Fig. 3. Obviously, suitable stops are provided to limit the degree of rocking movement of the shift plate 30 and furthermore

toggle springs

44 and 46 as described in Patent 2,517,989 are provided to accurately position the shift mechanism at either limit of its motion- In accordance with the teachings of this invention, shift plate 30 is provided with an arm 50 carrying a stud 52 which arm is rocked with plate 30 from the lower to upper case position and return. An actuating link 54 is positioned to interconnect the stud 52and a stud 56 carried by a gear sector 58 which is pivoted on stub shaft 60 carried by the typewriter frame. The gear sector 58 is mounted for engagement with an impression control mechanism 62, which, in turn, is supported for engagement with the typewriter letter cams, hereinafter described, by means of shaft 64 bushed in the typewriter frame.

Before describing in detail the structure of the impression control mechanism 62, reference is made to United States Patent 2,506,444Dodge-assigned to the same assignee as that of the present invention for a reference to the type bar drive mechanism and the method of controlling the extent of its power driven lift through the positioning of an adjustable stop in the path of the tail .of a letter cam. By changing the axial position of the adjustable stop-as shown in Fig. 2 of the subject Patent 2,5'06,444the type bar print force can be controlled, and sincea similar adjustable stop is provided for each of the type bar drive mechanisms, a uniform pressure per unit area can be provided for either (but not both) the lower or upper case setting of each type bar.

In accordance with the teachings of this invention, to

' provide an individually adjustable impression control earn stop for upper and lower case control of each of the letter cams, and more particularly to provide such an upper and lower case control for two entirely different typing conditions (or condition changes), the impression control member 62, as shown more completely in Fig. 6, is provided with four circumferentially spaced rows of adjustable stops which, in the illustrated embodiment, are set screws. One row of screws is utilized for the lower case while an adjacent row is used for the upper case position for any predetermined printing condition of the typewriter. Specifically (Fig. 6), each of four radially extending circumferentially spaced bosses 70 is provided with spaced, 'tapped holes along its entire length so that there will be one set screw for each of the forty-two letter cams-one for each of the type bars usually provided on the standard typewriter. An axial slit 71 in each of the bosses 70 houses a resilient strip 72 which has been compressed into its respective slit. The latter then has its outside edges rolled over to maintain a pressure on the adjusting screws to act as a locking device for each of the set screws passing through it. It should be stressed that the impression control member can be considered as being divided by parallel planes passing perpendicularly through its axis into fortytwo elements, each one of which has four set screws positioned 90 apart whereby a set screw (or adjustable stop) is provided for upper and lower case impression control for each of two different typewriter operating conditions. In this manner, an impression control mechanism is provided which will meet the objects of this invention when employed in conjunction with a positioning device which will lock the selected row of set screws in impression control position. I

Positioning device In order to position the proper rows of set screws for operative engagement with the tails of the letter cams, shaft 64 is provided (Fig. 3) with a gear 74 in mesh with the teeth of the sector 58. With this arrangement of parts, then in response to depression of the shift key lever 6, which as heretofore described causes the counterclockwise rocking of shift plate 30 on cross shaft 32, arm through its stud 52 pushes on actuating link 54 causing it to exert a force at stud 56 which rocks sector 58 counterclockwise about its pivot 60 thereby rotating the impression control member 62 clockwise 90 about its axis to position a different row of set screws for operative engagement with the tails of the letter cams.

Obviously, it is necessary that the rows of set screws be rotated an exact amount for engagement with the tails of the letter cams, and to accomplish this result, a detent mechanism is provided as shown in Figs. 2, 4 and 5. Specifically, a bushing 80 (Fig. 2) is mounted in the right side 82 of the typewriter frame both to support the impression control shaft 64, and also to mount a detent mechanism to properly position the selected row of set screws. A washer-like element 84 is mounted on the bushing 80 for movement transverse to the axis of and in juxtaposition with the bushing for a purpose hereinafter described. The washer element 84 preferably is made of resilient material, or one of the polyesters, in order to reduce the noise of the detent. The washer element has a diametrical groove which provides diametrically opposite radial slots 86, 88 (Fig. 4) each having one shoulder as, for example, the shoulder 90 (Fig. 2) which is cut away to provide a recessed portion 92 through substantially 180 of one face of the washer. A detent carry 94 is operatively connected to the shaft 64 in a manner hereinafter described and carries two pins 96, 98 (Fig. 4) which are so positioned that they rock 90 from their normal to their detent position. For example, if the detent carry 94 is rocked from the position shown in Fig. 4 so that the pin 96 engages the radial slot 88, one row of set screws will have been moved 90, so that it is in operative relation with the tails of the letter cams. With this arrangement then, the depression of shift key lever 6 causes the sector 58 to be rotated thereby rotating the impression control member 62, so that either

96 or 98 is positioned in its cooperative

radial slot

86 or 88 thereby insuring the proper location of a row of set screws for engagement with the tails of the letter cams.

It has been pointed out in the introductory paragraph of this specification, that it is necessary to provide a group impression control for typewriters whereby for any one setting whether it be upper or lower case position-the range of impression can be varied considerably to regulate the color density of a printed character. In accordance with the teachings of this invention, and in order to provide the required group control, the bushing mounted in the frame member 82 is provided with a transverse radial slot 100 (Fig. 4) while the face of the washer I 84 in contact with the bushing 80 has a transverse tongue 101 engageable with the slot 100 whereby the washer element 84 can be displaced transversely of the axis of the bushing 80 with the tongue 101 riding in the slot 100.

Substantially, the whole length of shaft 64 within the axial limitsof the central bore of the impression control member is provided wtih an eccentric 102 (Fig. 2) and when shaft 64 is rotated by means of a group control lever 104 rigidly secured to shaft 64, the motion of the eccentric 102 causes the impression control member 62 It has been mentioned that one of the objects of this invention is to provide a dual condition typewriter whereby the improved impression control may be used with either of two.sets of typewriter operating conditions,

and, in accordance with the teachings of this invention,.

two rows of impression control set screws are provided for each condition. In order to selectively position the desired pair of rows for operative engagement with the tails of the letter cams, a condition change mechanism is provided which comprises (note Fig. 1) a manually operated condition switch or button 106, mounted on an arm 108 rigidly secured to a .cross shaft 110 which, as shown in Fig. 2, is pivotally supported in the typewriter frame by means of

bushings

112, 114. Depending from the rod 110 and rigidly secured thereto, is a condition arm 116 which is rocked in response to a push on the button 106 from right to left in the direction of the arrow shown .in Fig. 1. The condition arm 116 carries a condition link 118 which is pivotally connected to a condition yoke 120. Yoke 120 which is rotatably supported on impression control member 62 carries a pawl 122 which is pivotally supported by the pin 124 and normally held out of engagement with the teeth of a ratchet 128 by means of a spring 126. With this structure, the ratchet 128 which is secured to impression control member 62 normally can rock under the pawl 122. However, upon movement of the condition switch in the direction of thearrow (Fig. 1) the depending arm 116 is rocked clockwise as shown in Fig. 1, thereby lifting the tail 130 of'pawl 122 thus engaging the pawl with the teeth of ratchet 128 and simultaneously, the thrust of link 118 caused by the clockwise rocking of depending arm 116 causes yoke 120 to be moved counterclockwise thereby rotating ratchet 128 counterclockwise. The ultimate objective of the operation of this mechanism is to produce 180" of rotation on the ratchet 128 and hence impression control member 62 thereby conditioning the latter for operative engagement with the letter cams under a second set of typing conditions. It should be noted that depending arm 116 ismaintained normally at its counterclockwise limit by the spring 132 which interconnects the depending arm 116 and a stud 134 extending laterally from the typewriter frame 82.

With reference nowto Figs. 1 and 2, detent carry 94 is connected to impression control member 62 through a second or condition detent mechanism 136 which comprises a condition detent carry 138 that is mounted for axially slidable movement on the shaft 140 which carries ratchet 128. The shaft 140, incidentally, along with impression control member 62 to which it is secured, is freely rotatable about the impression control shaft 64 and can be rocked by the control gear 74 through the condition detent 136. When the spring 142 normally positions the detent carry 138 so that its

pins

144, 146, engage the radially opposite grooves 148 (Fig. carried by one end of the detent carry 94, then the impression control member 62 may be rotated through 90 in response to the operation of the shift control mechanism.

Through the operation of the condition control button 106 (Fig. l), the

pins

144 and 146 can be displaced 180 relative to their position so that the second pair of rows of setscrews are located for operative engagement with the tails of the letter cams. In order to effect this 180 shift, the rocking of the depending arm 116 in response to the push on the condition switch button 106 brings the pawl 122 into engagement with ratchet 128 to rotate the latter and shaft 140 counterclockwise as viewed in Fig.1. This counterclockwise rotation breaks the

pins

144, 146 out of the radial grooves 148, by permitting the spring 142 to be compressed thereby allowing the condition detent carrier 138 to be slid along shaft axially to the left, as viewed in Fig. 2.v Successive pushes on condition switch button 106 cause the rotation of ratchet 128 a few teeth at'a time until the

pins

144, 146 are displaced from the position shown in Fig. l whereupon the pins drop into radially extending grooves 148, thereby selectively conditioning impression control member for a second set of typing conditions.

While this mechanism has been described for a typewriter having only two sets of conditions, it is readily apparent that by providing impression control member 62 with six rows of set screws, the typewriter, if necessary, could be constructed to act under three different sets of conditions; or if only two rows are provided, then the impression control mechanism would condition the typewriter for upper and lower case control as may be required for any one set of conditions.

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 is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a typewriter having a plurality of type bars each having a plurality of character positions, a plurality of rockable members selectively operable to drive an associated type bar to printing position, and a shift mechanism for selecting which character position on a type bar is to be printed, an impression control mechanism comprising a stop member having a plurality of rows of adjustable stops with one row being allocated for each character position on said type bars, means mounting said stop member in said typewriter for rocking movement to selectively position a predetermined row of stops in operating position for engagement with said rockable members thereby regulating the driving force imparted to a type bar by a rockable member, and link means interconnecting said stop member with said shift mechanism to position the allocated row of. stops in said engaging position in response to the selective operation of said shift mechanism.

2. In a typewriter having a plurality of multi-character type bars, a shift mechanism for selecting which character of a multi-character type bar is to be printed, and a plurality of rockable members selectively operable to drive an associated type bar to printing position, an impression control mechanism comprising an axially elongated member having a set of circumferentially spaced axial rows of adjustable stops with one row allocated for each character position on said type bars, means mounting said elongated member in said typewriter for rocking movement to selectively position a predetermined row of stops for operative engagement with said rockable members, and link means interconnecting said shift mechanism with said elongated member for rocking the latter to position a predetermined one of said rows for engagement with said rockable members in response to a selective operation of said shift mechanism.

3. In a typewriter having a plurality of two-character type bars, a shift mechanism for selecting which character of a two-character type bar is to be printed, and a plurality of rockable members selectively operable to drive an associated type bar to printing position, an impression control mechanism comprising an axially elongated member having a plurality of pairs of circumferentially spaced axial rows of adjustable stops, means mounting said elongated member in said typewriter for rocking movement to. selectively position either row of a pair of rows of stops for operative engagement with said rockable members, link means interconnecting said shift mechanism with said elongated member for rocking the latter to move either row of a pair into engagement with said rockable members in response to selective operation of said shift mechanism, and condition change means for moving a selected pair of said rows of stops into position to be operated in response to the selective operation of said shift mechanism.

4. In a typewriter having a plurality of multi-character type bars, a shift mechanism for selecting which character of a multi-character type bar is to be printed, and a plurality of rockable members selectively operable to drive an associated type bar to printing position, an impression control mechanism comprising an axially elongated mem ber having a plurality of sets of circumferentially spaced axial rows of adjustable stops, means mounting said elongated member in said typewriter for rocking movement to selectively position one row of a set for operative engagement with said rockable members, linking means interconnecting said shift mechanism with said elongated member for rocking the latter to move one row of a set into engagement with said rockable members in response to selective operation of said shift mechanism, and a condition change means for moving a set of said rows of stops into position to be operated in response to the selective operation of said shift mechanism, said condition change means comprising a ratchet wheel secured to said elongated member, a pawl engageable with said ratchet wheel to rotate the latter, and crank means for moving said pawl into engagement with said ratchet wheel to efiect the rotation of the latter to position a set of rows for operative engagement with said rockable members.

5. In a typewriter having a plurality of multi-character type bars, a shift mechanism for selecting which character of a multi-character type bar is to be printed, and a plurality of rockable members selectively operable to drive an associated type bar to printing position, an impression control mechanism comprising an axially elongated member having a set of circumferentially spaced axial rows of adjustable stops with one row allocated for each character position on said type bars, means mounting said elongated member in said typewriter for rocking movement to selectively position a predetermined row of stops for operative engagement with said rockable members, link means interconnecting said shift mechanism with said elongated member for rocking the latter to a selected position in response to a selective operation of said shift mechanism, and a cam operated group control device for displacing the axis of said elongated member, to vary the relative point of engagement between each of said adjustable stops and its respective rockable member thereby varying the imprint force of each type bar.

. 6. In a typewriter having a plurality of multi-character type bars, a shift mechanism for selecting which character of a multi-character type bar is to be printed, and'a plurality of rockable members selectively operable to drive an associated type bar to printing position, an impression control mechanism comprising an elongated cylindrical bar having circumferentially spaced axially extending bosses mounted thereon, a row of tapped holes in each of said bosses, with the axes of corresponding tapped holes in each of said bosses lying in the same plane, an adjustable set screw positioned in 'each of said tapped holes, means mounting said elongated member in said typewriter for rocking movement to selectively position a predetermined row of set screws for operative engagement with said rockable members, thereby regulating the driving force imparted to a type bar by its associated rockable member, and link means interconnecting said shift mechanism with said elongated member to effect said selective movement of the latter in response to operation of said shift mechanism.

7. In a typewriter having a plurality of multi-character type bars, a shift mechanism for selecting which character of a multi-character type bar is to be printed, and a plurality of rockable members selectively operable to drive an associated type bar to printing position, an impression control mechanism comprising an elongated cylindrical bar, four circumferentially spaced axially extending bosses mounted thereon, a plurality of tapped holes in each of said bosses with the axes of corresponding tapped holes in each of said bosses lying in a common plane, an adjustable stop member in each of said tapped holes, means mounting said elongated member in said typewriter for rocking movement to selectively position a predetermined row of said stop members for operative engagement with said rockable members, linking means interconnecting said shift mechanism with said elongated member for rocking the latter in response to selective operation of said shift mechanism, and a condition change means for moving a predetermined pair of said rows of stop members into position to be operated in response to the selective operation of said shift mechanism, each of said bosses on said elongated member having a resilient strip wedged therein to act as a locking device for said adjustable stop members passing through said tapped holes.

References Cited in the file of this patent UNITED STATES PATENTS