US 3302765 A
Description (OCR text may contain errors)
7, 1967 J. E. HICKERSON ETAL 3,302,765
CHARACTER SELECTION FOR SINGLE ELEMENT PRINTING MECHANISM EMPLOYING CAM PAIRS 3 Sheets-Sheet 1 Filed July 29, 1965 INVENTORS.
JOHN E HICKERSON HENRY R KRUSPE Feb. 7, 1967 E. HICKERSON ETAL 3,302,765
CHARACTER SELECTION FOR SINGLE ELEMENT PRINTING Filed July 29, 1965 MECHANISM EMPLOYING CAM PAIRS v 5 Sheets-Sheet 2 Feb. 7, 1967 CHARACTER Filed July 29, 1965 J. E. SELECT ECHANIS HICKERSON ETAL.
ION FOR SINGLE ELEMENT PRINTING M EMPLOYING CAM PAIRS .3 Sheets-Sheet 3 United States Patent CHARACTER SELECTHQN FOR SWGLE ELEMENT iRRIlli'SIING WCHANHSM EMPLOYING CAM AI John E. Hickerson and Henry R. Kruspe, Lexington, Ky.,
assignors to International Business Machines Corporation, Armonlr, N.Y., a corporation of New York Fitted Julv 29, 1965, Ser. No. 475,687 4 Claims. (Cl. 197-16) This invention provides a high speed but compact selector employing permutably operated face cams for positioning a printing matrix along coordinate axes.
Single element or character matrix printers employ mechanism responsive to a mark-space code for cating the individual characters of the matrix to be printed. A small number of characters can be located along a single coordinate in the case of a type 'wheel. It is more practical to locate larger numbers of characters along dual coordinates as in the case of cylindrical, spherical, or mushroom shaped matrices. Thus, it is understood that a major component of a single element printer is the converter for transforming mark-space coded coordinate data into analog coordinate displacement for positioning the character matrix.
The prior art contains a multitude of varied code-toanalog converters for this purpose. It is thus not difficult to find some conversion mechanism; rather, the problem lies in finding a mechanism that can operate at adequate speed while reliably and continuously providing precision output for a satisfactorily long useful life; be manufacturable at a reasonable cost, and occupy a minimum of space. All of the foregoing practical necessities rapidly become more difficult to attain as the number of characters on a matrix is increased.
With the ever expanding use of data processing and data communications equipment, the associated need for more available characters and symbols has resulted in a proposed standard code known as the ASCII or X3.4 code. This code includes seven information bits or channels which inherently provide for 128 pieces of information such as characters, symbols, or machine functions. Some 90 odd codes are presently assigned to characters. The ASCII Code is characterized by the absence of conventional shift codes of the type employed in the Bedot or Teletypewriter standard code. Thus, each character or function is totally identified by a single seven bit code. The practical problems enumerated above are thus further aggravated due to the lack of intermediate shift codes which otherwise would reduce the printing matrix travel. A printer constructed to operate on the ASCII Code will, by definition, have some input-output ability such as reading and/ or punching paper tape. However, it is desirable to also provide a keyboard for manual data entry.
A practical keyboard for ordinary rapid stenographic use is limited by operator considerations to a maximum of 40 to 50 keybuttons. Conventional typewriters and teletypewriters employ keyboards having shift keys which ordinarily do not modify the action of the keyboard, but shift a type basket or type matrix of the printing mecha nism to present a different character in response to substantially the same mechanical action from the keyboard. When conventional typewriters and teletypewriters are used in an input-output context, they employ shift codes to duplicate the keyboard act-ion. A printer that is constructed to operate internally on a code set lacking shift code must receive data from its keyboard in the same form. It is thus necessary to provide multiple mechanical outputs from each individual key button.
Accordingly, it has been an object of this invention to provide an improved practical code-to-analog converter for positioning a character matrix.
3,302,765 Patented Feb. 7, 1967 capable of moving directly between successive characters,
rather than passing through a home or starting position.
These and other important objects of our invention will appear to those skilled in the art from the following description of the novel concepts employed and a specific embodiment thereof.
One phase or novel concept of this invention involves a character selector having a plurality of aligned rotatable face cam pairs that each define some character-space-proportional increment by their effective cam rise. The cam pairs each include a rotatable cam and a nonrotatable cam both mounted on a common shaft. The rotatable cams are selectively rotated in response to an input code and the aggregate rise of the rotated cams is employed to a position a character matrix along its coordinate axes. The face cam mechanisms are particularly adapted to high speed operation since the various parts are in constant contact, thus eliminating opportunity for impact therebetween. Furthermore, the cams can be operated either serially or simultaneously with equal facility. It is preferred to divide large displacement increments between two rotatable cams to reduce the severity of cam interaction considering the small rotational distance available to achieve a large cam rise.
Rotation of the rotatable cams of each pair is conveniently controlled by individual cyclically operable clutches which, upon selective engagement, cause a predetermined cam rotation. To assure positive positioning of the selector mechanism output, cyclically operable detent means is provided, both on the selector output and at the printing matrix.
Another phase or concept of this invention relates to direct character selection which is achieved by cam position controlled reversal of control logic. Inasmuch as the face cams themselves are mutually unrelated as to their input controls, direct character selection is readily available. The control circuitry is arranged such that when a rotatable cam is in its nonextended position, closure of a clutch control code switch will operate to pick the clutch and permit cam rotation. The cam in its rotated position closes a logic reversing switch whereby subsequent closure of the code switch does not cause clutch operation, but non-closure will.
The foregoing and other concepts of this invention can be understood in greater depth from the following description of a specific preferred embodiment of the invention wherein particular reference is made to the accompanying drawings of which:
FIGURE 1 is a front perspective view of a code-toanalog converter or selector constructed in accordance with this invention :and schematically connected with a typical character matrix for purposes of illustration;
FIGURE 2 is an enlarged exploded perspective view of a cam mechanism shown in FIGURE 1;
FIGURE 3 is a front perspective view of a portion of the keyboard preferably to be employed with the selector mechanism of this invention;
FIGURE 4 is a circuit diagram showing a preferred wiring arrangement for interconnecting the keyboard of FIGURE 3 with the selector mechanism of FIGURE 1; and
FIGURE 5 is a circuit diagram showing a modified clutch control circuit for producing a no-restore home or direct character-to-character selection control of the selector shown in FIGURE 1.
Referring more specifically to the drawings in FIG- URE 1, there is shown a printer or typewriter T having a print head or character matrix similar to that disclosed in US. Patent No. 3,247,941 entitled, Printing Head With Means To Position Head Before Striking Movement Begins, of H. S. Beattie and J. E. Hickerson, filed December 20, 1963. The print head 10 is displaced vertically along a coordinate axis 11 in character space increments 12 as shown schematically by pulley 13 and is rotated along a coordinate axis 14 as shown schematically by a pulley 15. For simplicity, the print head 10 is shown as being stationary and cooperating with a moving platen 16, although it will be understood that the print head could be mounted on a movable carrier as disclosed in my aforesaid US. Patent 2,978,086.
The vertical displacement pulley 13 is positioned by spring loaded parallelogram mechanism 20 including end levers 21 pivoted about respective axes 22 and carrying pulleys 23 which operate closed loop tape 24. The tape 24 is operatively connected to and wrapped around pulley 13 whereby pivotal displacement of end levers 21 will transmit motion through the tape 24 to the pulley 13. The end levers 21 are interconnected by complementary drive bar 25 such that both will be positively driven an equiangular amount.
The drive bar 25 is provided With detent or homing notches 26 corresponding to each of its possible character selecting positions. A cam-operated detent pin or tooth 27 engages a notch 26 after the selection portion of each print cycle to positively locate the panallelogram mechanism 20 in an exact print character location. It will be noted that the above-mentioned application Serial Number 332,041 disclosed detenting means within the print head itself. It is preferred to provide both the print head detenting means and the selector detenting means as shown herein to divide the total detenting function and thereby minimize the amount of detenting force required within the print head where space and weight are at a premium.
A parallelogram mechanism 30, similar in structure and operation to mechanism 20, is provided for controlling the rotate control pulley and does not require a detailed description.
It will be understood that the combined position of the mechanisms and 30 as transmitted to pulleys 13 and 1 5 will select a single character position on the matrix of print head 10. The mechanism for driving the print head 10 against the platen 16 is not part of this invention. An appropriate driving mechanism is disclosed in US. Patent 2,919,002 entitled, Selection Mechanism for a Single Printing Element Typewriter, issued to L. E. Palmer, December 29, 1959.
The mechanism for positioning parallelograms 20 and 30, and hence matrix 10, comprises a pair of preferably coaxial code-to-analog converters or selectors 40 land 50 which produce an analog output in the form of variable axial length that is transmitted to the parallelograms 20 and 30, respectively, through sliding sleeves 28 and 31. Selector 40 comprises three cooperating face cam pairs 41, the individual construction of which is best shown in FIGURE 2.
Each face cam pair 41 comprises a contour cam 42 and a follower cam 43, both supported on a stationary shaft 44 having a central axis 45. Contour cam 42 is permitted to rotate and slide axially along the shaft 44. Follower cam 43 engages a keyway 45a and is thus per mitted to slide axially only along the shaft 45. The follower cam 43 of the left-most pair 41 in selector 40 is securely mounted on a base plate 46 that can be part of the stationary printer frame. The contour cam 42 has a camrning face 47 including a high dwell portion 47a and a low dwell portion 47b spaced :apart by predetermined angle a and connected by smooth transition or rise porti-ons 470. The high and low dwell portions are separated by a distance d which is proportional to the spacing between c-hanacters on the matrix 10. Preferably, the distance d varies between cam pairs 41 in a binary progression. For example, the distance d of one cam air 41 is proportional to one unit 12 of vertical displacement of the print head 10; another is proportional to two units of displacement; another is proportional to four units of the vertical displacement. The follower cam 43 of each pair 41 has a camming face 43 including a follower projection 48a having a rise portion 4812 that is greater in axial extent than the distance d of its associated contour cam 42.
Contour cams 42 are selectively rotated by motion transmitting means including individual control mechanisms 60 connected thereto through intrically formed gear or splined portions 61 by respective control pinions 62. The lengths of the spline portion 61 is selected to permit engagement with its control pinions 62 in any of the translated or axially moved positions of the associated contour cam 42. The control pinions 62 are mounted on a continuously active source of rotational energy in the form of rotating shaft 63 driven by pulley 64 and a suitable motor, not shown for conveying motion therefrom. Each pinion 62 includes -a selectively operable one revolution cyclic clutch having a pawl 65 and ratchet 66 which are normally held out of engagement by a latch 67 that is operated in response to an electromagnet or other control means 68. The gear ratio between the pinion 62 and the gear 61 is chosen to be 1:1, such that each operation of the electnomagnet 68 will produce a complete revolution of the face cam 41.
From the foregoing it will be understood that matrix 10 is positionable along axis 11 from zero to seven characters location increments by operation of selected control means 60. Rotational incrementing is obtained by selector mechanism 50 which is basically similar to selector mechanism 40 described above, and includes a plurality of face cam pairs 51 constructed basically the same as the pairs 41 described in detail above. Two separate face cam pairs 52 are employed, however, to obtain eight units of movement by having increment distances d (FIGURE 2) of four units each. Both of the contour cams in pairs 52 rotate simultaneously upon operation of the associated control means 60. The remaining cam pairs 51 are operated individually by their respective control means 60. The selector 50 is thus capable of lateral displacement correlative to any of 0 to 15 units of rotational character displacement of the print head 10.
In FIGURE 3 a keyboard K is shown that is similar in basic structure and operation to that disclosed in aforesaid U.S. Patent 2,978,086. As fully described therein, depression of a key button 71 actuates a character representing sword or stop member 72 by releasing it from a latch 73 to move downwardly under the influence of a spring 74 and pierce a stack of coded slides 75 or thin strips. The sword 72 also strikes bail 81 rotating it clockwise to close a cycle switch 82. Bail 81 further operates latch 83 to release spring biased arm 84 to move to the left of FIGURE 3 and permit slides 75 to move from a normally inactive position leftwardly under the influence of appropriate springs 76 to an active position. The coding in the slides 75 takes the form of long and short slots or openings 77 which cooperate with the selected sword 72 to permit only selected slides 75 to move to the left, thus representing the desired character in coded form. Electromagnets 85 and 36, respectively, restore the spring biased arm 84 and bail 81 to permit the selection of a second key button. The slides 75 which are permitted to move leftward close switches 78 which are individually associated therewith. As hereinafter explained in connection with FIGURE 4, closure of the slide controlled switches 78 activates respective control means 60 (FIGURES 1 and 2) to select a cycle of operation of the various face cam pairs to produce a character selection for printing.
The keyboard K shown in FIGURE 3 diifers from that of US. Patent 2,978,086 in that the stack of slides '75 actually includes three separate groups of code slides 91, 92 and 93 that operate alternatively to control the switches 78 in response to key button selection in combination with a shift status selection by shift keys 94, 95 and 96. The slides in each group 91, 92 and 93 are coded differently, as required, to produce three different coded outputs from each of the key buttons 71, thus permitting a practical number (between 40 and 45) of key buttons 71 to select between a large number of coded items.
The shift status selecting mechanism comprises the three shift keys 94, 95 and 96 which position, when depressed, an associated selecting finger or interposer 94a 95a or 96a into respective coded openings 97 whereby one group 91, 92 or 93 of slides will be permitted to move under control of sword 72 while the other two groups are inhibited. Latches 94b, 95b and 96b cooperate with respective shoulders 94c, 95c and 960 to hold a selected shift key in its depressed position and are interconnected by a bail 98 to release a previously selected shift key from its depressed position, such that only a single shift key will be held depressed at any one time. The keyboard K is operated by first depressing any of the shift keys 94, 95 and 96, thus selecting one of the groups of encoding slides 91, 92 and 93 and subsequently depressing a key button 71 to generate a coded representation of the selected data item at the switches 78 according to the particular keyboard case selected.
FIGURE 4 shows suitable circuitry for interconnecting the keyboard of FIGURE 3 to the selector mechanism of FIGURE 1, and also shows mechanism by which the selectors 40 and 50 of FIGURE 1 can be controlled di' rectly by a source of coded data such as a paper tape reader R of conventional construction In FIGURE 4 it will be seen that each of the pinions 62 of control means 60 are operated by respective electromagnets 68 controlled, in part, by slide operated switches 78.
Control means 60 are also operable from the tape reader R which closes internal switches (not shown) in response to sensing holes in the perforated tape. Cycling of the printer T is controlled by an electromagnet C to perform all the various cyclic functions as described in US. Patent 2,978,086 in a sequential timed relation. Operation of magnet C is controlled either by cycle switch 82 in the case of keyboard operation, or directly from the reader R as a function of reader cycle time. Preferably, the keyboard K is made ineffective to control the electromagnets 68 during a reader operation by a gang switching means R which is operative by electromagnet R at all times during reader operation.
The print cycle mechanism controlled by electromagnet C performs many print functions not shown and also drives cycle cams 87 and 88 which close individual switches to respectively restore the encoding slides 75 and terminate the cycle by operation of electromagnets 85 and 86.
The pinions 62 are permitted to rotate a complete revolution upon each operation of their associated clutch, thus driving their associated contour cams 42 a complete revolution passing through the high dwell portion 47a on the way. Accordingly, with the mechanism as shown in FIGURE 4, the print head will restore to a home position after each print cycle. It is desirable to have the print head move directly between various characters rather than return home. Direct selection permits the print operation to occur later in the print cycle as no time need he allotted to the restoration of the print head to its home position. In FIGURE 5 there is shown a modified control means 100 which permits the print head 10 to remain in its selected position and go directly between character selections, rather than through a home position. The mechanism shown includes a typical cam drive gear or splined portion 101 like 61 of FIGURE 2 and a control pinion 102 having a 1:1 ratio with the gear 101. This 0 mechanism differs from that of FIGURE 2 by employing a /2 revolution or 180 clutch 103 in place of the full revolution clutches disclosed above. The clutch 103 is of known construction, for example, a similar clutch is disclosed in U.S. Patent 2,919,002 mentioned above. Clutch 103 is controlled by a spring-biased latch 104 which is actuable by compound electromagnet 111. A feedback or position indicative pin 105 is carried by the pinion 102 and is positionable either as shown, or 180 displaced therefrom as the pinion 102 is displaced in 180 increments. When the feedback pin 105 is displaced 180 from the position shown in FIGURE 5, it operates intelligent data switch 112 to its closed operating state, thus indicating that the pinion 102 is in its actuated position.
The compound magnet 111 includes a core 113, a first coil or winding 114, and a second coil or winding 115. The coils 114 and are wound about the core 113 in opposite directions to produce opposite polarity when energized. Accordingly, operation of either coil alone will actuate the latch 104, whereas simultaneous actuation of both coils 114 and 115 will cancel any overall magnetic effect to prevent actuation of the latch 104. A pair of print cycle controlled switches 116 and 117 determine the point in the print cycle during which the control mechanism will be operated. Control of the circuit is by a typical slide controlled switch '78, like those shown in FIGURES 3 and 4, which produces either of two characteristically different signal inputs, i..e., open or closed.
Operation of the circuit shown in FIGURE 5 is as follows. With the mechanism in the position shown wherein reference arrow 106 points upward, closure of the switch 78 in response to keyboard selection of a code requiring a bit represented by control means 100, energizes the circuit including coil 114 when the cycle switch 116 is closed. Coil 115 is not energized because switch 112 is open. Latch 104 is picked temporarily 'as controlled by cycle cam 116 and permits a /2 revolution of the control pinion 102. Rotation of the pinion 102 rotates the cam drive gear 101 to position its associated cam in its high dwell or active position and reference arrow 106 will point downward. Upon selection of the next character, switch 78 will either be closed or not closed, depending upon the coding of the character selected. Assuming that the switch '78 is closed, thus again calling for the active (or arrow 106 down) position of the cam associated with drive gear 101, coil 114 will be energized as before upon closure of the cycle switch 116. However, pin 105 will have closed switch 112 and coil 115 will also be energized upon closure of cycle switch 117 to negate the overall magnetic flux of the compound magnet 111. Accordingly, the latch 104 will not be picked and the pinion 101 will remain in its active (arrow 106 down) position. Assuming, on the other hand, that the second selected code did not call for closure of switch '78, proper selection would require the return of pinion 102 and cam drive gear 101 to their home (arrow 106 up) positions. Switch 78, remaining open, would not energize coil 114 upon closure of cycle switch 116. However, switch 112, being closed by feedback pin 105, would energize coil 115 upon closure of cycle switches 116 and 117 to momentarily pick the latch 104, thereby permitting a rotation of the control pinion 102 to its home position.
Those skilled in the art will fully understand and appreciate that this invention provides a compact simple and reliable selector mechanism or digital-to-analog converter especially adapted to position a printing matrix having an extraordinarily large range of printing characters which are selectable either in response to a direct code input as from a punched tape, or in response to a keyboard constructed with a number of keys much smaller than the character locations on the printing matrix. While a specific embodiment and modification thereof has been shown for purposes of illustration, it will be understood that various modifications and additions can be 7 made to the disclosed mechanism without departiing from the novel concepts and spirit of this invention which are limited only by the appended claims.
1. In a printer having a character matrix that is positionable along at least one coordinate axis for character selection, the selector mechanism comprising:
a support shaft,
a matrix positioning mechanism mounted on said shaft and operatively connected to the character matrix for positioning the matrix along its coordinate axis,
said matrix positioning mechanism comprising a plurality of first face cams mounted on said shaft for rotatable movement,
a plurality of second face cams equal in number to said plurality of first face cams and mounted secure ly against rotation on said shaft adjacent respective ones of said first face cams to form a plurality of face cam pairs,
one of said face cams being held substantially stationary axially with respect to said shaft and the remaining face cams being mounted for axial movement on said shaft,
said pairs of cams being mutually interconnected for the transfer of axial motion therebetween,
one cam of each pair having a camming face that includes angularly spaced high and low dwell portions facing associated ones of the other cam of each pair, the distance between said high and low dwell portions being dimensionally related to increments between character locations on the character matrix,
each of said other cams of each pair having a follower portion that engages the camming face of associated ones said one cam of each pair,
a continuously active source of rotational energy,
rotative motion transmission means operatively connected to said energy source and individually to each of said first cams for effecting rotative motion thereof, when operated, for a predetermined angular increment sufiicient at least to bring said high and low dwell portions into alternate cooperative engagement with the follower portion of said pairs,
control means for selectively individually operating one or more of said transmission means,
means operatively connecting all of said cams to the character matrix for delivering the aggregate axial movement thereof to position the character matrix along its coordinate axis.
2. A printer as defined in claim 1 wherein said continuousily active source comprises a constantly rotating drive shaft;
said motion transmitting means comprises means operatively connected individually to each of said first cams for conveying rotative motion thereto and cyclical clutch means for selectively connecting said conveying means to said continuously rotating shaft for a predetermined angle of rotation thereof, and
said control means includes means for selectively operating said clutch means.
3. A printer asdefined in claim 2 wherein said cyclical clutch means functions to permit rotation of said first cams through 360 for each cyclic operation thereof.
4. A printer as defined in claim 2 wherein said cyclic clutch means operates to permit rotation of said first cam members through 180 for each operational cycle of said clutch control means, data means having two states of operation, each indicative of a respective rotational orientation of its associated first cam, signal input means for generating two characteristically different signals, and means responsive to said cam orientation indicative means and said signal input means for determining the operation of said control means.
References Cited by the Examiner UNITED STATES PATENTS 487,981 12/1892 Buckingham 178-34 X 2,110,957 3/1938 K-ollock -2 74-56 2,218,113 10/1940 Kleinschmidt 197-15 X 2,534,943 12/1950 Bcrgeson 74-56 2,769,029 10/1956 Howard 197-49 X 2,978,086 4/1961 Hickerson 197-16 3,057,210 10/1962 Stoddard 74-1 3,135,371 6/1964 Young 197-16 3,227,259 1/1966 Howard 197-49 ROBERT E. PULFREY, Primary Examiner.
E. S. BURR, Assistant Examiner.