United States Patent [191 Howard et al.
[ Feb. 5, 1974 HIGH SPEED PRINTER  Inventors: Robert Howard, Roslyn, N.Y.;
Prentice 1. Robinson, Hudson, N.l-l.
 Assignee: Centronics Data Computer Corp.,
 Filed: Apr. 6, 1972  Appl. No.: 241,782
 US. Cl. 197/1 R, 340/172.5  Int. Cl B41j 3/04  Field of Search 197/1; 340/1725 [5 6] References Cited UNITED STATES PATENTS 2,674,652 4/1954 Johnson et al. 197/1 R 2,980,227 4/1961 l-landley 197/20 3,601,297 8/1971 Funk et al 197/133 UX 3,625,142 12/1971 Bresler 197/1 X 3,174,427 3/1965 Taylor 197/1 X 3,332,343 7/1967 Sims 101/93 C 3,524,528 8/l970 Peyton 197/20 X 2,869,455 [[1959 Knutsen 197/1 X Primary Examiner-Robert E. Pulfrey Assistant Examiner-R. T. Rader Attorney, Agent, or Firm-Ostrolenk, Faber, Gerb & Soffen  ABSTRACT A control system for printers in which an elongated paper document is moved at a substantially constant speed. A plurality of reciprocally mounted solenoid operated print wires are mounted at spaced intervals upon a movable assembly arranged to move along a line transverse to the direction of movement of the paper document. The print wires are selectively operated by electronic and electromechanical means to impact an inked ribbon against the paper document for printing and/or plotting. The movable assembly is designed to fully compensate for the movement of the document to assure that all dots printed along a single row will form a straight line. While only selected ones of the print wires need be operated at any given instant, those selected for operation are all driven against the inked ribbon simultaneously to provide high speed printing and/or plotting of the dot matrix type.
Means are provided, in one preferred embodiment, for paper movement of one, five and twelve dot feeds to respectively provide for dot row spacing, character line spacing and line feed.
23 Claims, 27 Drawing Figures PAIENTEB 5W4 saw mar 13 PAIENIED FEB 51914 saw on Of 13 PAIENIEB FEB 5 I974 SHE! 08 0F 13 PATENTEU FEB 5 4 SHEEI 07 0F 13 PAIENTEUFEB SHEET 08 0F 13 PATENTED 51974 SHEET 10 0F 13 PAIENIEBFEB um SHEET 12 HF 13 men SPEED PRINTER BACKGROUND OF THE INVENTION The present invention relates to printers and more particularly to high speed impact printers of the dot matrix type in which linear movement of the components comprising the printer is significantly reduced to provide print operating speeds not heretofore obtainable.
Dot matrix printers are well known in the art and are typically comprised of a matrix of print wires (usually arranged in an ordered matrix of seven rows and five columns) in which the print wires are selectively impacted against an inked ribbon which, in turn, is driven against the paper document to form any desired character. The print wires are then physically shifted or moved, in unison, relative to the paper document to the next position to print the next character or symbol. Upon completion of a single line of characters or symbols, the print wire bundle making up the 5X7 matrix is rapidly shifted back to the starting position, the document is advanced and the next line of characters is printed in a similar fashion.
In order to reduce the amount of mass required to be moved at high speed during the printing operation, an improved version of the aforementioned technique has been developed, and is set forth in detail in copending applications Ser. No. 35,405, filed May 7, 1970 and Ser. No. 179,457, filed Sept. 10, 1971 and assigned to the assignee of the present invention, wherein the 5 7 matrix of print wires is replaced by a set of seven substantially vertically aligned print wires which are advanced in stepwise fashion five times per character to form substantially the same 5X7 dot matrix as that described hereinabove. This arrangement still, nevertheless, requires the acceleration, movement and deceleration of the print wires at a very high repetitive rate, thereby severely limiting the print speedand increasing down time due to wearing of the moving components. Also, the distance traveled by the print head is double the width of a line of print.
BRIEF DESCRIPTION OF THE INVENTION The present invention is characterized by providing a high speed impact printer of the dot matrix type in which the print wires undergo significantly reduced linear movement transverse to their longitudinal axes, and wherein the paper document is moved at a cooperating speed during the printing operation so as to greatly enhance overall operating speed, print capabilities and simplicity of the device.
The present invention is comprised of a plurality of solenoids, each being provided to drive a slender print wire. All of the solenoids are mounted upon a movable mounting assembly with each of the print wires being guided by suitable guide means so as to be arranged along a substantially horizontal line with their forward ends being positioned to reciprocate within a small diameter opening formed in a jewel bearing whose forward face is in close proximity to the printer platen. An elongated inked ribbon is positioned between the forward surface of the platen and the jewel bearing so as to be driven into a paper document riding over the platen when impacted by the print wires. The ribbon is preferably drawn between a pair of reversibly movable spools so as to continuously move the ribbon in either the forward or reverse direction during the printing operation to provide for even wearing of the ribbon.
The paper document may be perforated along either or both of its marginal edges so as to cooperate with drive means capable of advancing the paper document at high speeds, or may be moved by a conventional rotatable roller type platen.
The printer electronics is comprised of input means for receiving data in either serial or parallel fashion and feeding the data in parallel fashion into a multistage shift register capable of storing a multiplicity of binary words, each representing a particular character or symbol.
Once the register is fully loaded, or is loaded to the desired amount (i.e., to respectively print a full line or less than a full line) the contents of selected stages of the register (containing the binary bits representing a character or symbol) are applied to conversion means for each character which may (for example) be a character generator adapted to provide output signals in binary form at selected ones (or all) of its plurality of output terminals representing the first or top line of the five by seven matrix for the associated characters. These signals are, in turn, employed to selectively trigger the operation of the print wire solenoids to form dots at spaced intervals along the top line of the characters to be printed. The mounting assembly, which is continuously advanced, is operated at discrete small intervals to print each dot group. Suitable stepping means, such as, for example, a counter, is employed for triggering the character generators to provide binary output signals at the appropriate output terminal of the character generator representative of the next dot in the top-most row of the five by seven matrix. These signals are then employed to selectively operate the associated print wire solenoids. The stepping operation continues until all dots along the top row of the five by seven matrix have been printed, at which time the entire top row (i.e., first dot row) of characters (for example) have been printed. The mounting assembly is then returned to the start position while the paper document continues to move so that, upon return to the start position, the dot spacing between rows is automatically obtained. The second row of dots of the five by seven matrices are then formed in a similar manner.
Uponcompletion of the seventh dot row the document feed device is caused to operate to separate the completed line of characters from the next line to be printed. During this stepping operation, hereinafter referred to as a five dot skip, binary code groups for the next line of characters are shifted into the register, and as soon as the register is loaded (either completely or to the extent desired) the operation is continued for the next line of characters. Each line of characters is printed in a similar fashion.
A line of characters of double width may be printed by causing each column of the 5X7 matrix forming a character to be printed twice, thus creating a character of double width, if desired. As a further alternative, characters of a single row may be both double and single width if desired.
As a further alternative, the high speed impact printer may be adpated to print or plot curves by selective energization of the print wire solenoids to cause one or more than one of the dots on any given line to be printed whereby those dots, in cooperation with the available thorugh the above described features and techniques.
By moving the horizontally aligned solenoid mounting assembly at a slight angle relative to the horizontal direction, the paper document may be moved continuously, and formation of a perfectly horizontal straight row of dots is assured, thus significantly reducing the complexity of the mechanism for moving the paper document.
The spacing of the solenoids over a distance slightly less than the width of the paper document enables an entire row of dots to be printed while the mounting assembly physically moves only a fraction of the width of a full line of characters.
Perfect registration of the dot patterns formed is assured through the use of a registration means which also serves to identify the location of the print solenoids at any given instant.
The electromechanical system for controlling and synchronizing all of the printer operations provides for one, five and 12 dot feeds to respectively perform dot row spacing, character line spacing and high speed line feed(s).
The printer solenoid carriage assembly is preferably a split arrangement to accommodate ledger type entries or other applications in which two printer solenoid assembly halves may be operated to the exclusion of the other.
The printer head assembly is further designed in one alternative embodiment, to provide for rapid reversal of the print wire positions to assure even wearing of the print wires through long continued use.
Whereas the description of the preferred embodiments teaches a printer capable of providing a five by seven matrix for each character position, embodiments having up to a nine by nine matrix per character position in the line printing mode are also contemplated. Such an arrangement requires a modification whereby the print head is shuttled nine times per line of characters, where a three-dot skip is provided between lines of characters. The nine by nine matrix provides for printing of both upper and lower case characters as well as below the line symbols such as cursors, commas, colons and the like. The nine by nine matrix also may be adapted to print complex special characters, and foreign language characters, such as ideographs.
OBJECTS OF THE INVENTION It is therefore one object of the printer invention to provide a novel high speed impact printer in which printing of characters is undertaken partially serially and partially parallel for each line of characters, and serially line by lineto form characters and/or symbols to plot curves.
Another object-of the present invention is to provide a novel high speed impact printer in which the number of moving parts employed is significantly reduced, so as to reduce the amount of mass otherwise required in conventional impact printers of the dot matrix type.
A still further object of the present invention is to provide a novel high speed impact printer of the dot matrix type in which the double width characters may be printed in a simple manner.
Another object of this invention is to provide a novel feed mechanism for dot matrix printers to perform both character printing and curve plotting.
Still another object of the present invention is to provide a novel split printer solenoid assembly for mutually exclusive operation of the solenoid assembly halves to perform ledger entries and the like.
BRIEF DESCRIPTION OF THE FIGURES These as well as other objects of the present invention will become apparent when reading the accompanying description and drawings in which:
FIG. 1 is a perspective view showing an array of print wires and operating solenoids which are employed in the apparatus of the present invention and incorporating the principles thereof.
FIG. 2 is a diagrammatic view showing the pertinent mechanical components of the paper feed system and its associated optical and electronic circuitry for controlling dot registration and identifying solenoid location.
FIG. 2a is a detailed perspective view of one planetary gear assembly of FIG. 2.
FIGS. 2b-2d are left end, sectional and right end views, respectively, of one clutch assembly of FIG. 2.
FIG. 3 is a block diagram showing the electronics employed in the printer of FIGS. 1 and 2.
FIGS. 4a-4c are top, front and end views respectively, of a split printer solenoid assembly.
FIG. 5 shows some of the characters generated by the printer of FIG. 1.
FIGS. 6a-6n are detailed schematic diagrams of the diagrammatic blocks shown in FIG. 3.
FIG. 7a is an elevational view, partially sectionalized, showing another print head embodiment of the present invention.
FIG. 7b is a front view of the assembly of FIG. 7a looking in the direction of arrows 7b-7b.
FIG. is a top plan view showing a portion of the assembly of FIG. 7a looking in the direction of arrows 7c-7c.
DETAILED DESCRIPTION OF THE INVENTION The printer of the present invention is an impact printer utilizing a five by seven dot matrix to produce each character when in the printing mode or, alternatively, utilizing any one of a plurality of the print wires when operating in the curve plotting mode. The unit, in one preferred embodiment, prints an array of characters per second. The printer in this embodiment, is capable of printing 80 characters per line with a varying paper width dependent only upon the needs of the user. The device utilizes an elongated paper document or any other suitable paper feed device, and generates of the order of 12 dot lines to the inch including the space between the lines with 10 characters per inch horizontally. The printer requires no special paper and can produce an original plus seven copies, with the seventh copy being very readable. It should be understood that a greater or lesser number of print wires may be employed, dependent only upon the particular application.
PRINTING METHOD The printing. of characters is accomplished by moving the paper documentat a substantially constant speed upon the platen by mechanical movement. The top row of dots of all characters are formed in the following manner:
The movable mounting assembly, in one preferred embodiment, has eight solenoids mounted at uniformly spaced intervals. In the case where each line comprises 80 characters, the solenoid print wires are spaced at one inch intervals. In the case of characters to the inch, and five dot columns per character and a dot space between characters, the solenoids are selectively operated up to a maximum of 59 times during movement, or a total distance of approximately one inch in the print direction to complete each row of a line of characters. The mounting assembly is then returned to the start (i.e., left-hand-most) position in readiness to print the next dot row of a line of characters. Seven rows of dots are printed to form a line of (up to 80) characters, each defined by a five by seven matrix pattern. Obviously, any other arrangement may be employed to print a greater or lesser number of characters.
Each individual solenoid independently forms up to ten characters in a fashion which is most analogous to the manner in which an electron beam scans the face of a cathode ray tube (i.e., in the line-by-line fashion employed in television receivers).
Accurate spacing of the dots in each row, and hence the time of printing is initiated by a strobe pulse derived from an optical pick-up head which cooperates with a stationary slotted Mylar strip having a slot provided for each dot position along the horizontal row of dots. A spacing of one dot size between characters is provided. Alternatively, the optical pickup head and light source may be stationary and the slotted strip may move with the print head.
The printing of the characters is accomplished by the print wires which are solenoid driven to move the print wires against an inked ribbon to produce dots on the original copy. The firing of the solenoids occurs only during the presence of the strobe pulse derived from the optical pick-up head. This pulse is of a duration of 450 microseconds with a relax time of 550 microseconds. The characters are printed such that one slice (i.e., dot row) of each of the characters in a line (which may, for example, be 80 characters) is printed along each row of dots. Seven closely spaced rows of dots are printed, thereby forming a five by seven matrix for each character printed within a line of characters. Spacing between horizontal rows of dots is of the order of 0.015 inches and between character lines is of the order of the spacing between five horizontal rows of dots.
COORDINATION BETWEEN PAPER MOVEMENT AND SOLENOID MOVEMENT The movement of the paper, in one preferred embodiment, is constant regardless of the fact that single line feeds or multiple line feeds are desired. A single motor is used as a source for the power necessary to move the platen at a constant speed. The mounting assembly moves the solenoids at a slight angle to the horizontal direction to synchronize relative vertical movement of the solenoids with vertical movement of the paper to assure printing of a horizontal straight row of dots. During the return stroke, the relative downward movement of the solenoid mounting assembly cooperates with the continuous upward movement of the paper to provide accurate spacing between horizontal rows of dots.
In the preferred embodiment of the USASCII Code is employed. This code is a six-bit code enabling 64 dif ferent combinations of characters to be generated. Obviously, a greater or shorter code bit length may be em ployed in cases where a greater or lesser number of characters are desired for the printer. The timing count pulses derived from the column position counter of character registration control unit are employed to control the firing of the eight solenoids associated with each character generator. The first dot of the first dot row for the first, eleventh, twenty-first and seventy-first characters to be printed on that line are formed during column position timing unit No. l, the second dot of the first dot row for the aforesaid characters to be printed are formed during time unit No. 2, and so forth, until the top row of dots of the aforesaid characters has been completed. Thereupon, the sixth timing unit is used to allow for a space, and thereafter the first dot of the first row of dots for the second, twelfth, twenty-second, and seventy-second characters are printed. This operation continues until the first dot row of the line of characters being printed is completed.
The last timing unit is employed to advance the row counter and return the solenoid carriage to the start position, which provides the proper dot spacing between the top-most row of dots and the next row of dots.
The row counter output, together with the output data from the character register, causes the character generator to develop signals representative of the next row of dots for the line of characters presently being printed. The column position counter again controls the solenoids to print the first through the fifth dots on the second dot row for the first, eleventh, twenty-first and seventy-first characters, then a space, then the first through the fifth dots on the second dot row for the second, twelfth, and seventy-second characters, and so forth, until all dots of the second dot row are completed. The third through the seventh rows of dots are printed in a like fashion. It should be noted that only one character generator (to be more fully described) is provided, with the character generator being sequentially controlled during the examination of each character. Sequential coupling is accomplished by shifting the encoded data in the character register one position to the right upon the occurrence of every sixth count (i.e., space condition) of the row position counter. The first encoded character shifted out of the right-hand end is then shifted into the left-hand end of the register through a feed-back loop. This continues until 10 coded characters have been shifted, at which time the end of line signal resets the solenoid carriage to the start position to begin a new row of dots. As the carriage is returning to the start position, the coded characters are rapidly shifted to the right (and inserted at the left end) by oscillator 19a which is controlled by the end of line signal until a special coded start character arrives in the right-hand-most (i.e., first position) of register 15 so that all coded characters are returned to their original positions within register 15, in readiness for printing the next row of dots.
FIG. 5 shows the dot patterns for some typical characters, with the dot spacing being exaggerated relative to normal spacing to simplify their understanding. The solid circles indicate dots to be printed. In each case the order of printing is row 1, dot positions 1, 2, 3, 4,
. until row 2 is complete; and so forth, until seven dot rows are completed, thereby completing one line of characters.
The seven output lines of the character generator are selectively coupled through a multiplexer and buffer register, to the inputs of associated solenoid driver circuits where the signals are amplified by suitable amplifiers to produce a current controlled pulse to the solenoids to cause selective firing of the associated print WlI'eS.
The printing portion of the system consists of the solenoid and print wires which provide for the impact printing of the characters. The solenoids, when operated, drive the print wires against an inked ribbon to form dots on the paper document which dots are arranged at selected positions along each horizontal dot row. The rearward ends of the print wires are coupled to solenoid armatures as is shown and described in detail in copending applications Ser. No. 37,815, filed May 15, 1970 and Ser. No. 152,598, filed June 14, 1971. The forward ends of the print wires extending from each solenoid are positioned for reciprocal mounting within a jewel bearing provided with openings for each print wire, which openings are arranged along an imaginary horizontal line.
FIG. 1 is a perspective exploded view to facilitate an understanding of the invention and showing the solenoid and print wire carriage assembly 10, which is comprised of a movable platform 11 having solenoid mounting member 12 provided with a plurality of tapped apertures 12a for threadedly engaging the forward threaded portions 13a of solenoids 13. The solenoids are described in detail in copending applications Ser. NO. 37,815, filed May 15, 1970 and Ser. No. 152,598, filed June 14, 1971, which descriptions are incorporated herein by reference thereto. For purposes of the present invention, it is sufficient to understand that the solenoids 13 are each provided with solenoid coils for operating an armature to drive its associated print wire 13b in the impact direction (see arrow A) against the force of a biasing spring. Release of the electrical energy places the print wire under control of the biasing spring which causes the print wire to move in the direction of arrow B to return the print wire to the non-printing or standby position.
Each of the solenoids is provided with a pair of leads 130 for coupling to the system electronics, and more particularly, to the solenoid drivers (see circuit of FIG. 60) for energization of the solenoid coils.
The forward or impact ends of the print wires 13b impact the inked ribbon 15 and paper document to form dots whereby adjacent dots are spaced apart a distance of the order of 1/60th of an inch. Portion 12a of the mounting member 12 is provided with jewel bearing members 14 to retain the print wires in the desired horizontal alignment. Alternatively, the Wires, which are mounted within guide tubes 13d, may each be provided with jewel bearings at their forward ends. The actual dimensions of FIG. 1 have been exaggerated to clarify an understanding of the structure. The jewel members 14 each slidably receive the forward ends of their associated print wires 13b. The front face of each jewel 14 is positioned in close proximity to ribbon 15, substantially aligned with the jewels and extending between feed and take-up reels 16 and 17, respectively. Rollers l8a18d are spring loaded and act to maintain the ribbon extending between ribbon reel 16 and 17 under tension. Operation of any of the solenoids 13 causes the associated print wire to be impacted against the inked ribbon 15, and thereby drives the ribbon against a paper document. 20, positioned between inked ribbon 15 and a backing platen 21, to cause the dots to be formed. The total linear movement in the impact direction of the wires is approximately 0.015 inches. Under normal operation, the end of each print wire is approximately 0.006 inches from the ribbon and paper. This spacing is due to the fact that a great deal of force is absorbed by the ribbon and the paper upon impact.
The solenoids move along a slightly inclined path. A pair of rails 22 and 23 are arranged in spaced parallel fashion, and are inclined at the desired angle relative to the longitudinal axis of platen 21. Movable platform 11 rides between rails 22 and 23. Cylindrical bearings 24 are provided between the grooves 22a and 23a in rails 22 and 23 and grooves 11a and 1 1b in platform 11. The head 12, upon which the solenoids 13 are mounted is tilted at its left-hand end relative to platform 11 (by a suitable shim, for example) so as to align head 12 in the horizontal direction and parallel to the central axis 21a of platen 21. A pair of projections 11c (see FIG. 2) secured to the underside of platform 11 extend downwardly and receive a shuttle cam 1 14b formed on cylinder 114a. The cam sits in the space between projections 11c. Shuttle cam 114 is rotated by motor M through a mechanical coupling (to be described in connection with FIG. 2) between motor M and shaft 103. One full revolution of cam 114 moves platform 11 toward the right from the start (left-hand-most) position to the right-hand-most position and returns the platform to its start position (moving right to left).
Although an intermittent type paper feed mechanism becomes more complicated due to its need to advance the paper accurately through such a small distance, the paper may nevertheless be advanced in a row at a time fashion and beheld motionless during the printing of each row of dots. This arrangement avoids the need for inclining rails 22 and 23. Operation in all other respects remains substantially the same as described above.
Considering FIG. 1a of copending application Ser. No. 204,024, 60 representsa dot printed at time t Immediately thereafter, solenoid S (solid circle) moves to position S to print dot 61. During this time, dot 60 has moved upward to location 60' (due to the fact that the paper moves continuously in the direction of arrow A). Thereafter, the solenoid moves from S to S to print dot 62. During this time the paper moves upward (arrow A) moving the first dot from location 60' to 60" and moving the second dot from location 61 to 61'. By diagonal movement of solenoid S (through its carriage 40) all three dots lie along a straight line (dotted line 63). It should be noted that the spacing between the dots in FIG. la has been exaggerated to facilitate an understanding of the operation, typical center to center spacing between dots being of the order of 0.015 inches. Typical dot diameter is of the order of 0.0145 inches. I
The speed of movement of paper 20 and the carriage assembly is further so chosen so that during the time it takes the carriage assembly to move to its right-handmost position and then return to its left-hand-most position (which limiting positions may be controlled by stops) the paper 20 will have moved a distance equal to the spacing between adjacent dot rows forming a character. This is aided by the fact that whereas the carriage assembly moves upward and to the right during printing, it moves downward and to the left during carriage return. In one preferred embodiment, the paper moves a distance of the radius of a dot during printing so that during a carriage return the movement of both the paper and the carriage through one radius each amounts to a total combined movement of one diameter of a dot.
FIG. 2 shows the major components of the printer utilized to perform the various types of line feed operations required for successful operation of the printer. As was previously described, so far as the preferred embodiment is concerned, the underlying concept is to provide for continuous movement of the indeterminate length paper document when printing and to provide for high speed skips or paper movement during nonprinting periods. The three modes of operation are as follows:
Mode l In this mode the paper document is continuously advanced at printing speed while the shuttle head, i.e., the printer movable solenoid assembly shuttles to the right and then to the left to perform the printing and return operations respectively.
Mode 2 In the line printing mode, and after a line of characters has been printed, paper is advanced to perform a high speed skip to provide a spacing of five dot lines between the line of characters just completed and the next line of characters to be printed. During this operation the paper moves at more than four times the rate at which the paper is advanced during the normal printing operation.
Mode 3 Line Feeds In this mode, no printing is performed and the paper is advanced at a rate of speed which is more than 20 times greater the speed of advancement during the normal printing mode. As many line skips as are required may be performed in a consecutive fashion to provide greater than line to line spacing between lines of characters.
Referring specifically to FIG. 2, there is shown therein a printer mechanism 100 comprised of a motor M having an output shaft 101 provided with a gear 102. A second shaft 103 also provided with a gear 104 is mechanically coupled to gear 102 by means of a pulley (timing belt) 105 having protrusions or teeth adapted to engage the teeth of gears 102 and 104.
Gear 104 is free wheelingly mounted upon shaft 103 when clutch C, is disengaged. upon the engagement of C shaft 103 is caused to rotate with the rotation of gear 104. Gear 104 is actually a two-part gear having a portion 1040 whose gear teeth engage the teeth of timing belt 105 and having a second portion 104b also free wheelingly mounted relative to shaft 103, but always being rotatable in synchronism with portion 104a. The gear teeth of gear portion l04b mesh with the gear teeth of gear 106 which is free wheelingly mounted upon shaft 107 when clutch C is disengaged. However,
upon engagement of clutch C shaft 107 will rotate in unison with the rotation of gear 106.
The gear teeth of gear 106 mesh with the gear teeth of gear 108 which is free wheelingly mounted upon shaft 109 so long as clutch mechanism C is deenergized. Upon energization of clutch mechanism C shaft 109 is caused to rotate in unison with gear 108. It should be noted that, so long as motor M is energized, gears 104, 106 and 108 are always rotating. However,
as will be more fully described, only one of the clutch mechanisms C -C is normally energized at any given time so that only one of the shafts 103, 107 and 109 will normally be caused to rotate at any given instant.
Each of the clutch mechanisms C -C is provided with an actuating solenoid mechanism 110, 111, and 112, respectively which serves to actuate its associated clutch mechanism. As will be more fully described, each clutch mechanism remains in the actuated state for only one complete revolution or a predetermined portion of one revolution and is adapted to automatically become deactivated upon the completion of one revolution (or a portion thereof).
In the printing mode (Mode No. 1) solenoid 110 is energized causing clutch C, to become actuated for one complete revolution thereby locking shaft 103 to gear 104 and causing shaft 103 to rotate for a full revolution. A gear 1 13 is locked to the opposite end of shaft 103 as is a shuttle cam mechanism 114 comprised of a solid cylindrical member 114a having a continuous cam member ll4b in the form of a flange. Shuttle cam 1l4b rides between a pair of projections 11c, 11c extending downwardly from platform member 11 upon which head 12 is mounted. Circles 13 represent the solenoids fixedly secured to head 12 as shown best in FIG. 1.
A full rotation of gear 104 and shaft 103, gear 113 and shuttle cam 114 causes the printer solenoid assembly to move to the right as shown by arrow A a distance of the order of one inch during the first half of a full revolution to perform the printing operation and immediately thereafter causes platform 11 to move to the left as shown by arrow B after completion of the printing operation to return the platform 11 to the rest or ready to print position which is the position occupied by platform 11 in FIG. 2.
At this time the movement of the paper must be synchronized with the shuttling of the platform 11 and hence the solenoids 13. This is accomplished by means of a gear train comprised of gear 113 which meshes with gear 115 mounted upon shaft 116. Gear 115, in turn, meshes with gear 117 mounted upon shaft 118. The opposite end of shaft 118 is provided with a gear 119 which rotates with the rotation of gear 117 and shaft 118 and which meshes with gear 121 which forms part of a planatary gear assembly 120. The planatary gear assembly 120 is shown in FIG. 2a and is comprised of gear 119 mounted upon shaft 118. Gear 119 meshes with a planet gear 121 mounted on a common shaft 122 with planet gear 123. Shaft 122 is mounted within a suitable opening provided in sun gear 124 so as to be capable of being free wheelingly rotated relative to sun gear 124. Both planet gears 121 and 123 are locked to shaft 122 so that any rotation of either gear is imparted to the other.
Planet gear 123 meshes with output gear 125 which is mounted upon shaft 126. Sun gear 124 is mounted upon shaft 127. Whereas shafts 118, 127 and 126 are arranged along a common longitudinal axis 128, it should be noted that these three shafts are independent of one another as can best be seen in FIG. 2.
Sun gear 124 meshes with a gear 130 mounted upon shaft 107 which cooperates with gear 106 (previously described) in a manner to be more fully described. In the printing mode (Mode No. l) shaft 107 and gear 130 remain stationary causing sun gear 124 to remain stationary. With gear 104 locked to shaft 103, a driving 1 1 connection between gear 104, shaft 103, gears 113, 115, 117, shaft 118 and gear 119, causes gear 121 to rotate. Shaft 122 thereby rotates causing rotation of planet gear 123 which meshes with and drive gear 125. Rotation of gear 125 causes its shaft 126 to rotate which, in turn, causes rotation of gear 132 which is locked to shaft 126. Gear 132 drives a gear 133 mounted upon and locked to shaft 134. Shaft 134 has provided at its opposite end a gear 135 which is locked thereto and which forms one of the gears of a second planetary gear assembly 136. This planetary gear assembly is substantially identical to the planetary gear assembly shown in FIG. 2a and hence an additional figure therefore will be omitted for purposes of simplicity. It is sufficient to understand that this planetary gear assembly 136 is comprised of a sun gear 137 mounted to selectively rotate about shaft 138. Gear 137 is provided with an opening for free wheelingly receiving shaft 139 upon which is mounted a pair of planet gears 140 and 141 which are locked to shaft 139. Planet gear 140 meshes with gear 135 while planet gear 141 meshes with output gear 142 which is fixedly secured to shaft 143 so as to rotate in unison therewith. A gear 144 is fixedly secured to the opposite end of shaft 143 so as to rotate with the rotation of gear 142 and shaft 143. Gear 144 meshes with a gear 145 locked to shaft 146. The opposite end of shaft 146 is provided with a gear 147 locked thereto. Gear 147 meshes with a gear 148 which is fixedly secured to shaft 149. Also fixedly secured to shaft 149 is a timing gear 150 which cooperates with a timing gear 151 by means of a timing belt 152 which is entrained about timing gears 150 and 151.
Timing gear 151 is mounted upon and locked to an elongated shaft 153 which runs substantially the entire width of the printer mechanism and has mounted thereon a pair of adjustable pin feed mechanisms 154 and 155 for accommodating paper of varying width. Each of the pin feed mechanisms is adapted to rotate in unison with the rotation of shaft 153. These mechanisms are provided with equally spaced pins 154a and 155a, respectively, which cooperate respectively with similarly equispaced openings provided along the opposite parallel sides of the paper document so as to feed the paper document thereby.
As was described hereinabove, actuation of clutch C, occurs by means of pulsing the clutch solenoid 1 (for 35 milliseconds in the preferred embodiment) to provide for one full revolution of the shuttle cam 114. One full revolution provides for movement of the printer solenoid platform 11 from the start position (shown in FIG. 2) to the right-handmost position (during the first half revolution) and subsequently returning platform 11 to the start position (i.e., the no-print portion of the revolution). Simultaneously therewith through the gearing connections described hereinabove, the paper document is fed through a distance equivalent to the spacing between adjacent dot rows. In the preferred embodiment the paper is moved at a constant rate of speed which is 0.1 inches per second.
The clutch mechanism which may be employed for the three clutches C -C as shown in FIGS. 2b-2d wherein FIG. shows a side view partially sectionalized, FIG. 2b shows a left-hand end view of the assembly of FIG. 2c and wherein FIG. 201 shows the righthand end view of the assembly of FIG. 20. The clutch assembly C, (it being understood that the other clutch assemblies are similar) is comprised of a core member 161 having a tapped aperture 161a for receiving a threaded fastener to secure a shaft 103 passing through the central opening 16111 in core member 161. Shaft 103 is then locked to core member 161b so as to undergo any rotation imparted to core member 161. The clutch assembly is further comprised of a gear member 162 provided with a central opening 162a. Core member 161 is fitted through this central opening. A ring 163 overlies the hollow annular space between the central opening in gear 162 and the outer periphery 1610 of core member 161 and is locked in position by a locking ring 164. Three cylindrical shaped rollers 165a, 1651: and 1650 are arranged between the outer periphery 1610 of core member 161 and the inner periphery of a ring 166 mounted within the central opening 162a in gear 162. Three arcuate shaped portions 167a, 167b and 1670 are arranged in a space between ring 166 and the periphery 1610 of core 161 and act to maintain a spacing between the central axes of cylindrical rollers a-165c.
As can best be seen from FIG. 2d, the periphery 1610 of core member 161 is provided with three flat portions 1610-1, 1610-2 and 1610-3 arranged respectively at 120 angles relative to one another about peripheral portion 1610. The inner periphery of ring 166 makes rolling engagement with cylindrical rollers 165a-l650 while the flattened portions 1610-l through 1610-3 make engagement with cylindrical rollers 165a-1650, respectively. With these flat portions arranged at a particular angular orientation, rollers 16501-1650 are pinched between ring 166 and peripheral portion 1610 causing any rotation of gear 162 to be imparted to core member 161 and hence to be imparted to shaft 103 which is fixedly locked to core member 161. The shifting of the roller bearings 16511-1650 relative to flat surfaces 1610-1 through 1610-3 is accomplished by means of a lever arm 168 mounted to pivot about a pin 169 secured to a substantially circular shaped disc 170. A second pin extends through lever 168 and plate 170. This pin 171 is provided with an annular groove 171a which receives one end 172a of a biasing spring 172 whose opposite end is secured to a pin 173 which is mounted to plate 170. Spring 172 normally biases lever 168 in the clockwise direction as shown by arrow 174 in FIG. 2a.
Lever 168 is provided with a notched portion 168a having an engaging surface 168b which is arranged to be struck by the actuating pin 110 of clutch solenoid 1 10.
The operation of the one revolution clutch assembly is as follows:
In the case where the clutch assembly is normally deactivated, solenoid 110 is deenergized at such time causing actuating pin 1 10a to abut against the engaging surface 168b of lever 168. This causes lever arm 168 to be urged in the counterclockwise direction about its pivot pin 169 against the biasing force of spring 172 resulting in the movement of arcuate section 16712 through a coupling provided between head 171b of pin 171 and an arm portion 167b-1 of arcuate section 167b. This arrangement moves the cylindrical bearings 165a-165c to the center portion of the straight surfaces 1610-l through 1610-3, respectively. In this position rotation of gear 162 is not imparted to core member 161 and hence shaft 103 is prevented from rotating. It