US3029921A - Control mechanism - Google Patents

Description

April 1962 J- M. REYNARD 3,029,921

CONTROL MECHANISM Filed March 9, 1961 2 Sheets-Sheet 1 Fig.1

l 67 70 2 i I i INVENTOR JOHN M. lawn!) BY a f t MU April 17, 1962 J. M. REYNARD CONTROL MECHANISM 2 Sheets-Sheet 2 Filed March 9, 1961 INVENTOR JOHN M Y United States This invention relates to a differential controI mechanism, and more particularly relates to a novel type of differentially operating device for positioning the printing head of a matrix printer, said device having an indexible output element and a plurality of control input members operatively connected to said output element and selectively operable in coded combinations for varying the extent of indexing movement of said output element.

In matrix type printing machines the printing head is successively displaced through predetermined distances in order to serially bring the respective desired type to an Operative position at the printing point of the machine. In this type of operation the means provided for displacing the printing head through variable strokes must partake of a very accurate high speed motion. The positioning mechanisms previously proposed or used for controlling such indexing motions of the printing head of matrix machines have not always been satisfactory because of being unreliable in accuracy, having inherent high inertia forces, and/or being too complex and expensive for practical purposes.

One object of the instant invention is to provide a reliably accurate differential positioning mechanism for efficiently indexing the printing head of a matrix type printer.

Another object of the invention is to provide a novel motion transmitting and control mechanism having an output shaft which is adapted to be driven by a plurality of serially interconnected differential or epicyclic units which may be selectively operatedin coded combinations so as to cumulatively rotate said output shaft to variable desired extents.

Anotherobject of the invention is to provide a novel positioning mechanism for the printing head of a matrix printer, said positioning mechanism comprising an output shaft which is adapted to be connected so as to be rotated by the collective action of a plurality of interference-fit 'ball type diiferential units that are selectively operated in coded combinations so as to rotate said output shaft through various predetermined angles.

Another object of the invention is to provide a novel positioning mechanism for matrix printers and the like whereby a plurality of planetary type differential units are serially connected together so that the output means from each unit is connected to the drive input means for the next unit, the respective control input means for the units thereby being free to modify the, movement being transmitted by said differential units.

Other. objects and many of the attendant advantages of this invention Will be .readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings in which like reference numerals designate like parts throughout the figures therer FIGURE 4 is a schematic view of the mode of interconnecting the control elements of the instant apparatus.

Referring to FIGURE 1' there is shown a conventional type cylindrical matrix printing head 10 having a circumferentially disposed and uniformily spaced array of type 11 mounted on the cylindrical periphery thereof. The head 10 is adapted to be rotatably indexed to successive printing positions by means of a positioning mechanism 12 that has an output shaft 13; the matrix head 10 being rotatably adjustably clamped on said output shaft 13 by any suitable means. A hammer 14, operatively mounted and connected so .as to be actuated by a solenoid 15, is provided for cooperating in the usual manner with the various type 11 of the matrix printing head that are moved to the printing point of the machine so that various characters corresponding to said type may be printed on a record sheet 16 through the medium of the inked ribbon 17. The type for one desired set of characters is located on a 180 arc of the periphery of the head 10 while the type for another desired set of characters is located on the other 180 arc of the head periphery. The head 10 will be rotatably shifted 180 when a change in the character sets to be used is desired. When using either set of type the type head is normally disposed in a central home position and is capable of swinging up to substantially to six discreet printing positions on either side of said home position.

The positioning mechanism 12 is generally comprised of four ball type differential or epi- cyclic units 20, 21, 22 and 23, FIGURES 1 and 2, which are operatively connected in series so as to form a cumulative motion transmitting means for the outputrshaft 13. The four differential units are respectively operated by means of four control input arms 24, 25, 26 and 27; these arms being selectively arcuately displaced in coded combinations so as to cumulatively effect a predetermined rotation of the output shaft 13 and the matrix head 10. The lowermost differential unit 20 includes a tubular hub 30 that is formed with an annular groove 31 in which four planetary balls 32 are adapted to roll. Each ball 32 is closely retained in one of four uniformly spaced apertures 33 formed in a ball retainer ring 34. An outer ring member 35 having an inner cylindrical surface 36 is mounted over and surrounds the balls 32. The three basic ,elements comprising the first dilferential unit 20, namely hub 30, balls 32 together with the ball retainer ring 34, and ring member 35, are relatively radially dimensioned so that when they are assembled as shown in FIGURE 2 an interference fit exists. During the normal operation of the positioning mechanism 12 the tubular hub 30 remains rotatably fixed. When it is occasionally desired to shift the matrix head so that the secondset of type may be used the tubular hub is merely rotatably indexed through an arcuate stroke sufiicient to produce a 180 rotation of the said output shaft 13. The means to so index hub 30 may comprise any suitable device, such as a one half revolution clutch or the like, which is diagrammatically illustrated at 37, 40 of FIGURES 1 and 3. In normal operations however the tubular hub 30 will remain fixed and unless otherwise indicated it will be assumed during the subsequent discussion of the operation of the instant apparatus that this normal condition exists. The ring member 35 is secured to said radially extending control input arm 25 which in turn is biased by means of a spring 43 into normal engagement with the fixed common bar stop 44. Arm 25 is adapted to be swung into engagement with and held againsta fixed common bar stop 45 by means of a solenoid 46. As will be apparent when the hub 30 remains rotatably fixed a s'wingingmovement of the input arm 25 will cause .the balls 32 to roll. around the grooved periphery of hub 30 3 which in turn will cause the ball retaining ring 34 to rotate about the axis of the unit. This differential type motion of unit 20 will take place in a non-slipping manner due to the said interference fit between the parts.

The ball retainer ring 34 is axially extended and is provided with a second set of four uniformily spaced apertures 50 in which are respectively disposed a second set of four closely fitting planetary balls 51 which are adapted to roll around the annular grooved portion 52 of a second hub 53. Hub 53 is formed with depending axial shaft portion 54 which extends through the tubular hub 30 and to which is fixed said control input arm 24. The outer end of arm 24 is biased by means of a spring 55 into normal engagement with the bar stop 44 and is adapted to be rotatably displaced into engagement with the bar stop 45 by means of a solenoid 56. A second outer ring member 57 having a cylindrical inner surface 58 is mounted over and surrounds said planetary balls 51. The three basic elements comprising the second differential unit 21, namely the hub 53, balls 51 together with the ball retaining ring, and the ring member 57 are relatively radially dimensioned so that when they are assembled as shown in FIGURE 2 an interference fit exists. As will be apparent when the input arm 24 is pivotally displaced the resultant rotation of the hub 53 will be transferred to the balls 51 which in turn transmit this rotational movement to the ring member 57 in an amount dependent on whether or not the balls 51 are permitted by the ball retaining ring 34 to roll or just to rotate on their own geometric axes. Whether or not the ball retainer ring 34 rotates depends on whether or not the input arm 25 has been operated as noted above. This differential type movement of unit 21 will take place in a non-slipping manner due to the said interference fit between the parts.

The ring member 57 is axially extended and is provided with a reduced portion which is formed with an annular groove 60 and which defines the hub 61 of the third differential unit 22. A third set of planetary balls 62 are mounted for rolling movement in the groove 60 and are respectively closely fitted into the four apertures 63 formed in a third ball retaining ring 64. A third outer ring member 65 having a cylindrical inner surface 66 is mounted over and surrounds the balls 62. The ball retaining ring 64 is secured to the said control input arm 26. Arm 26 is biased by means of a spring 67 into normal engagement with the bar stop 44 and is adapted to be rotatably displaced into engagement with and held against bar stop 45 by means of a solenoid 70. The three basic elements comprising the third differential unit 22, namely hub 61, balls 62 together with the ball retainer ring 64, and the ring member 65 are relatively radially dimensioned so that when they are assembled as shown in FIGURE 2 an interference fit exists. As will be apparent when the input arm 26 is pivotally displaced the resultant rotational movement of the ball retaining ring 64 will be transferred through balls 62 to the ring member 65 in an amount dependent upon the rotational movement, if any, of the hub 61. The extent of rotation of hub 61 will, as noted above, be determined by whether or not the input arms 24 and/or 25 have been operated. This differential type movement of unit 22 will take place in a non-slipping manner due to the interference fit between the parts.

The ring member 65 is axially extended and is provided with a reduced portion that defines the ring member 71 of the fourth differential unit 23. The ring member 71 is formed with an inner cylindrical surface 72 which is mounted over and surrounds a fourth set of four planetary balls 73. Balls 73 are respectively closely fitted into a set of uniformly spaced apertures 74 formed in a fourth ball retainer ring 75 and are adapted to roll around an annular groove 76 formed in a hub 77. Hub 77 is integrally connected to the said output shaft 13 of the positioning mechanism and the ball retaining ring 75 is secured to the said control input arm 27. Arm 27 is biased by means of a spring 78 into normal engagement with the bar stop 44 and is adapted to be displaced into engagement with and held against the bar stop 45 by means of a solenoid 81. The three basic elements comprising the fourth ditferential unit, namely hub 77, balls 73 together with the ball retainer ring 75, and the ring member 71 are relatively radially dimensioned so that when the parts are assembled as shown in FIGURE 2 an interference fit exists. As will be apparent when the input arm 27 is rotatably displaced the resultant rotation of the ball retaining ring 75 will be transmitted through balls 73 to th hub 77 and output shaft 13 in an amount which is determined by the extent of rotation, if any, of the ring member 71. The rotation of ring member 71 is as noted above determined by whether or not the input arms 24, 25 and/ or 26 have been operated. This differential type movement of unit 23 will take place in a nonslipping manner due to the said interference fit of the parts.

It will now be apparent that the matrix head 10, FIG- URE 1, may be moved from a central home position to any one of several operative positions by the selective operation of the various control input arms 24, 25, 26 and 27 of the differential type positioning mechanism 12. The ratios of the diameters of the hubs, balls and rings of the different units 20-23 may be adjusted so that the desired sizes of angular displacements of the matrix printing head 10 occur in response to the operation of the respective control input arms 24-27. By way of illustration the effective relative diameters of the various parts may be adjusted as follows.

Where D equals approximately /8 inch and each input arm is capable of being displaced through an operative arcuate stroke of approximately 15 the output shaft 13 and head 10 will be given substantially the following clockwise and counter clockwise rotative dis placements by the noted selective displacement of the control input arms 24-27.

Degrees of resultant rote.

tion of head 10 from nor- COntt'Ol input arms operated: mal central home position 25, 27 25, 27, 24 +75 27 +60 27, 24 +45 25 +30 25, 24 +15 none 0 24 15 26, 24, 27- 30 26, 25 45 26, 24, 25 60 26 75 26, 2 90 One diminuitive positioning mechanism 12 has been constructed wherein the overall length is about 1.25 inches and the diameter of the largest one of the cylindrical surfaces (66) is in the order of only /1 of an inch. As will be apparent the operation of such a small size mechanism will involve low inertia forces and such opera tions may occur at relatively high speeds with a minimum of noise, vibration, etc.

In effect each of the differential units 20-23 has a drive input means, a control input means and an output means. The output means for one differential unit is connected to the drive input means of the next differential unit; for .example, the output means (balls 32 and the lower portion of the ball retainer ring 34) for the differential unit 20 is connected to the drive input means (balls 51 and the upper portion of the ball retainer ring 34) for the next differential unit 21, the control input means for the units 20 and 21 being respectively defined by the ring 35 together with its associated control input arm 25 and the hub 53 together with its associated control input arm 24. In similar fashion the output means (ring member 57) of the differential unit 21 is connected to the input drive means (hub 61) of the differential unit 22, the control input means here comprising the balls 62 and the ball retaining ring 64 together with the associated control input arm 26. In turn the output means (ring member 65) of the differential unit 22 is connected to the input means (ring member 71) of the differential unit 23, the balls 73 and ball retainer ring 75 together with the control input arm 27 here constituting the control input means for the differential unit 23. Although the differential units 20-23 are interconnected in series in the functional sense that the output means of one unit is connected to the drive input means of the next unit, what particular element of a differential unit constitutes the drive input means, the control input means or the output means for that particular differential unit may vary. For example, the hub of one unit may constitute the drive input means for that unit while the hub of the next unit may be an output means for this next unit. Conversely for example, the control input means for one unit may constitute the ring member of that unit while the control input means for the next unit may constitute the planetating balls and retainer of this next unit. Thus any one of the basic parts or elements of any given diiferentialunit may be structurally connected to any one of the elements of the next unit. Further the mode of interconnecting a first to a second differential unit may differ from the mode of interconnecting the second to a third differential unit.

the operation of the instant apparatus. Five bails 101, 102, 103, 104 and 105 are pivotally mounted by any suitable means on the machine side frames and respectively have laterally swingable body portions 106, 107, 110, 111 and 112 which extend "across the machine and beneath the normal complement of key levers such as 113. Bails 101-105 are yieldably maintained in their normal FIGURE 4 positions by any suitable spring means and upon counter clockwise displacement are adapted to close the respectively associated normally open switches 114, 115, 116, 117 and 118 which are respectively proximate to said bails and which are suitably supported on the machine frame. Switches 114-117 are electrically connected so as to respectively control the operation of said solenoids 56, 46, 70 and 81 which respectively actuate said input arms 2427. The switch 118 is electrically connected so as to control the operation of the hammer solenoid 15. Each key lever is provided with a similar short depending catnming tooth 120 and in addition is provided with a coded number of longer camming teeth 121. The teeth 121 are adapted to arcuately displace the respective adjacent associated bails and thereby close the related switches in response to the selective depression .of the key levers.

In operation after any given coded combination of switches 121 have been closed and the related control input arms have been thereby actuated to properly position the matrix head the relatively short tooth 120 of the FIGURE 4 shows an exemplary means for controlling to print the desired character on the record sheet 16. It will be apparent here that due to the relative shortness of tooth 120 no printing action will occur until after the positioning mechanism 12 has displaced matrix head 10 to the desired indexed position. having different coded numbers and positions for teeth= 121 are successively depressed, different type 11 will be sequentially brought to printing position by the action of the differential positioning mechanism 12.

When the second set of type on the other 180 half of the periphery of head 10 is to be used the shift means 37, 40 are operated to thereby displace the head through 180 from the normal home position to an alternate home position. Thereafter the selective operation of the control input arms 24-27 will serve to bring the various type of this second set to printing positions in a manner similar to that above described for said first set of type 11 to be used.

If after prolonged use of the instant apparatus a slight amount of slippage has occurred between the various parts of the differential positioning mechanism 12 then the matrix head 10 may be unclamped from the output shaft 13, rotatably adjusted to proper phase relation and then reclarnped on said output shaft 13. Thereafter all the type 11 and all the differential units will again be in proper phase condition. It will be apparent that conventional type gears may be used in place of the various balls, ring members and hubs; and that a similar differential positioning mechanism can be correspondingly used to control an axial shifting movement of the matrix head 10 where more than one circumferential band or row of type 11 is to be mounted on said matrix head.

The instant mechanism 12 has been shown and described here as a positioning means for matrix printers; however it may be utilized in several other applications with equal facility; for example, the mechanism may be employed as an arithmetic unit wherein movement of the output shaft 13 represents an algebraic sum of quantities represented by the displacements of the control input arms 2427. Also it will be noted that the time displacement characteristics of the motion of any one of the control input arms 24-27 will produce corresponding time-displacement characteristics in the resultant effects on the movement of the output shaft 13. Further the unit or mechanism 12 may be used simply as a motion transmitting means wherein a fixed or variable amplification or reduction of an input movement is desired.

While there is in this application specifically described one form which the invention may assume in practice,

it will be understood that this form of the same is shown for purposes of illustration only and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

The invention claimed is:

1. In a printing device; a matrix printing head, a plurality of type mounted on said matrix head, means for creating a printing pressure between said head and a record sheet that is to be printed on, a positioning mechanism for sequentially variably positioning said matrix head, said positioning mechanism comprising a plurality of coaxially arranged differential units which are effectively serially connected between each other and said matrix head, each of said differential units including a hub element, a pluarity of planetating elements adapted to roll around said hub element, and an output element, a control input arm operatively connected to one of the elements of each of said differential units, and control means for selectively operating said input arms,

2. A position mechanism for matrix printers and the like; comprising a plurality of differential type units, a first one of said units having three basic parts namely a hub portion, at least one rollable element, and an outer member, one of said parts constituting an output means for said unit, a second one of said parts constituting a As different key leversv drive input means for said unit, and the third one of said parts constituting a control input means for said unit, a second one of said units also including three basic parts that are respectively similar to those of the first differential unit, a third one of said units also including three basic parts that are respectively similar to those of said first unit, the output means of the first differential unit being connected to the drive input means of said second differential unit and the output means of said second differential unit being connected to the drive input means of said third differential unit whereby selective operation of the three control input means for said units will cause variable displacements for the output means of said third differential unit, the mode of interconnecting said units being such that connection between the parts of said first and second differential units is different from the connection between the parts of said second and third differential units.

3. Apparatus as defined by claim 2 wherein in at least one of said differential units, the hub portion is defined by a cylindrical member, the rollable element is a ball, and the outer member is a ring member which surrounds said balls and hub portion, and wherein said parts when assembled have a radial interference fit so as to thereby make possible a non-slipping connection therebetween.

4. A positioning mechanism for matrix printers and the like; comprising a first differential unit having three basic parts namely a hub portion, at least one rollable element and an outer member, one of said parts constituting an output means for said unit, a second one of said parts constituting a drive input means for said unit, and the third one of said parts constituting a control input means for said unit, a second differential unit which also has three basic parts that are respectively similar to those of said first differential unit, the output means for said first unit being connected to the drive input means for the second unit such that the individual actuation of the control input means for each of said units will respectively produce different rotative displacements of the output means of said second unit.

5. Apparatus as defined by claim 4 wherein the output means for the first differential unit is defined by a different one of the three basic unit parts than the output means for said second differential unit.

6. Apparatus as defined by claim 5 wherein the control input means for the first unit is defined by a different one of said basic parts than the control input means for said second unit.

7. Apparatus as defined by claim 5 wherein the output means of the first differential unit comprises the rollable element of said first differential unit, and the drive input means of the second differential unit comprises the rollable element of said second differential unit,

8. Apparatus as defined by claim 5 wherein the output means from the first differential unit comprises the outer member of said first differential unit, and the input drive:

means from the first differential unit comprises the outer member of said first differential unit, and the drive input means of the second differential unit comprises the outer member of said second differential unit.

10. Apparatus as defined by claim 5 wherein the roll-- able element of at least one of said differential units com prises a ball that is adapted to roll along the respective effective outer and inner surfaces of the associated hub portion and outer member, these three basic parts of said one differential unit being relatively dimensioned and assembled so as to have a non-slipping interference fit therebetween.

11. In a printing device; a matrix printing head, a plurality of printing type mounted on said matrix head and adapted to be selectively moved to a predetermined printing point, means for creating a printing pressure between the selected type located at said printing point and a record sheet that is to be printed on, a positioning mechanism for variably displacing said matrix head so as to successively bring different type to said printing point, said positioning mechanism comprising a plurality of coaxially arranged differentially operating units which are serially interconnected, each unit having a hub element, at least one planetating element adapted to roll around said hub element, and an output element all interconnected so as to form a differentially operating unit, a control arm connected to one of said elements in each of said units, each control arm being movable to rotatably displace said matrix head to a predetermined extent, and means operable to sequentially actuate different coded combinations of said control arm.

12. Apparatus as defined in claim 11 wherein at least one of said differentially operating units includes a hub, a plurality of balls and an outer ring member, said balls adapted to frictionally engage and roll around the outer and inner peripheries of the associated hub and ring member respectively.

References Cited in the file of this patent UNITED STATES PATENTS 2,077,962 Smith Apr. 20, 1937 2,643,753 Wohlgemuth June 30, 1953 2,661,683 Beattie Dec. 8, 1953 2,680,970 Durkee June 15, 1954 2,687,087 Crowell Aug. 24, 1954 2,847,105 Carroll Aug. 12, 1958 2,861,668 Beccio Nov. 25, 1958 2,867,168 Roth Jan. 6, 1959

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