US3456078A - Retraction type carrier mechanism - Google Patents

Description

L. A. NASH I 3,456,078

RETRACTION TYPE CARRIER MECHANISM July 15; 1969 5 Sheets-Sheet 1 Filed Sept. 20, 1965 INVENTOR LEONARD A. NASH ATTORNEY July 15, 1969 NASH 3,456,078

RETRACTI0N TYPE CARRIER MECHANISM 5 Sheets-Sheet 2 Filed Sept. 20, 1965 July'15, 1969 I 1.. A. NASH 3,456,073

RETRAOTION TYPE CARRIER MECHANISM Filed Sept. 20, 1965 3 Sheets-Sheets @Illlllllg'umw FiG. 4

FIG, 5 v 55 I \w/ I United States Patent 3,456,078 RETRACTION TYPE CARRIER MECHANISM Leonard A. Nash, Evanston, Ill., assignor to Teletype Corporation, Skokie, 11]., a corporation of Delaware Filed Sept. 20, 1965, Ser. No. 488,555 Int. Cl. H041 15/34, 15/29, 17/16 US. Cl. 178-45 20 Claims ABSTRACT OF THE DISCLOSURE A mechanism for retracting the type carrier of an aggregate motion telegraph printer including a ratchet Wheel, a pawl for advancing the ratchet wheel, a cam mounted on the drive shaft of the printer for operating the pawl and thereby advancing the ratchet wheel one step for each cycle of operation of the drive shaft; a cam on the selector cam sleeve of the printer, a lever operated by the cam on the sleeve for disengaging the pawl from the ratchet each time a character is received by the printer thereby resetting the ratchet; a link in the aggregate motion mechanism having a knee action joint, a spring for normally maintaining the knee action joint straight, a bell-crank for breaking the knee action joint, a cam for actuating the bell crank, a clutch for connecting the bell crank cam to the drive shaft of the printer, a slide operated by the ratchet wheel upon being advanced a predetermined number of steps without being reset for actuating the clutches of the aggregate motion printer and for actuating the bell crank clutch to lower the type carrier to its lowermost printing position and then to break the knee action link thereby retracting the type carrier to a non-printing position.

This invention relates to type carrier retracting mechanisms for printing telegraph apparatus and more particularly to mechanisms for retracting the type carrier of a page printing telegraph apparatus out of the printing field to expose printed copy to view.

Printing telegraph page printers have been developed which utilize type carrying mechanisms that shift type elements carried by them to present the elements to a printing position. One of the problems involved in such mechanisms is the problem of exposing the last character printed to view. For example, the mechanism disclosed in Patent No. 2,911,472 granted to R. G. Griflith on Nov. 3, 1959, moves the type carrier each time the character is to be printed; but, without manual intervention and rotation of the platen, the last several characters printed are hidden from view by the type carrier. This defect is overcome in the mechanism disclosed in Patent No. 2,505,729 granted to W. I. Zenner on April 25, 1950, by providing a mechanism for retracting the type carrier, after the printing of each character, to a position where the last character printed can be readily discerned. Another mechanism for moving a type carrier out of its operative position to expose the characters in the last line printed to view is disclosed in Patent No. 2,906,821 granted to R. G. Griffith on Sept. 29, 1959. The mechanism provided in the apparatus disclosed in that patent senses the selector cam shaft and the function shaft of the telegraph printer and retracts the type carrier to its lowermost printing position when both shafts are stopped. With this mechanism it is barely possible to see the most recently printed characters by looking over the top of the type carrier; but the retraction of the type carrier to the lowermost printing position is invariably fixed by the function mechanism of the printer.

With the introduction of telegraph printers which operate at much higher speeds than previous printers, the exposing of the last character printed presents a timing 3,456,078 Patented July 15, 1969 problem. The retraction of the type carrier to expose the last printed character after each character is printed, as is done in the printer shown in the above-identified Zenner patent, uses an appreciable portion of the transmission time.

An object of the present invention is to render readily visible the last character printed on a high speed telegraph printer equipped with a type carrier.

Another object of the present invention is to provide a mechanism for retracting a type carrier of a printing telegraph receiver to a position completely outside of the printing field.

A further object of the present invention is to provide a type carrier retraction mechanism for a printing field.

A further object of the present invention is to provide a type carrier retraction mechanism for a printing telegraph receiver which is independent of the timing of the receiver.

A still further object of the present invention is to provide a mechanism for retracting a type carrier of a printing telegraph receiver to a position completely outside of the printing field in response to a non-receipt of input signals by the receiver for a predetermined period of time.

In accordance with one embodiment of the invention, an aggregate motion telegraph page printer having certain elements in common with the basic structure used in the page printer disclosed in Patent No. 2,505,729, granted to W. J. Zenner on Apr. 25, 1950, is provided with a ratchet type counter which counts the revolutions of the main shaft occurring since receipt of the last character. Receipt of a character by the printers selector mechanism resets the counter to normal. If, however, the counter registers a predetermined number of rotations of the main shaft without being reset, the vertical positioning mechanism of the printer is actuated and it retracts the type carrier to fully expose the last character printed for viewing.

A complete understanding of the invention may be had by reference to the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a fragmentary side elevational view of a telegraph page printer equipped with a type carrier and showing the general arrangement of the vertical positioning mechanism therefor together with a ratchet type counter and the mechanism for resetting it, parts being broken away to show other parts of the apparatus positioned behind them;

FIG. 2 is a view similar to FIG. 1 but showing some of the parts in positions opposite to the positions they occupy in FIG. 1 and also showing mechanism for resetting the clutches which control the actuation of the type carrier;

FIG. 3 is a transverse sectional view of the printer taken just back of the structure shown in FIG. 2 with the counter mechanism and its mounting plate removed;

FIG. 4 is also a transverse sectional view through the printer taken in the area just back of the structure shown in FIG. 3 and showing the driving mechanisms for the clutches and their associated latches;

FIG. 5 is another transverse sectional view just back of the structure shown in FIG. 4 and showing the eccentric and aggregate motion leverage mechanisms which serve to position the type carrier vertically;

FIG. 6 is a sectional view taken along line 6-6 of FIG. 1 showing a detail of the code bar connection to the clutch-stop-slide positioning mechanism; and

FIG. 7 is a detail view of a ribbon retraction mechanism.

Since the present invention involves only the vertical positioning of a type carrier the horizontal positioning mechanism forms no part of the invention and any suitable horizontal positioning mechanism may be used.

In the drawings the same reference numerals are used to designate the same elements throughout the several views. In FIG. 1 there is shown a type carrier which corresponds to the type carrier 99 of the aforementioned Zenner patent; and like the type carrier of the Zenner patent, the type carrier 10 rides transversely of the apparatus on a rail 11 corresponding to the rail 163 of the Zenner patent. A pair of elevator bars 12, one of which is shown in FIG. 1, is positioned adjacent to the ends of the rail 11 and serve to impart reciprocatory motion to it. Each bar 12 has a slot 13 in it, into which there extends a shouldered guide screw 14 that serves to confine the bar 12 to movement in a vertical path. At its lower extremity each bar 12 has a rack formed on it for engagement with a gear 21. The gears 21 are fixed to a shaft 19 which extends across the printer and supports the gears 21 in mesh with their associated racks 20. The gears 21 on the shaft 19 constrain bars 12 to always move together and thus the type carrier 10 in any of its selected horizontal positions will move into cooperative relation with paper (not shown) positioned between a platen I18 and an inked ribbon 16 carried by a ribbon positioning mechanism 17. Consequently, when reciprocation is imparted to one of the bars 12, both bars 12 and the rail 11 are moved rectilinearly to raise or lower the type car rier 10 to the selected one of four possible vertical printing positions.

The bar 12 (FIG. 1) is driven by a single slide 22 which is moved to various vertical positions by a lever 23. The lever 23 is in turn positioned vertically by an aggregate motion mechanism 29 (FIG. 5) which includes the lever 23 and links 30 and 31. The lever 23 is urged to the left (FIG. 5) by a contractile spring and is pivotally connected at its right end to the slide 22 which in turn slides on a surface 34 forming a part of the main framework of the printer. The driving link 30 is an ordinary drive link and is pivoted to the lever 23 at pivot 32. Link 30 is moved to either one or the other of two vertical positions by an eccentric 39 which is rotatably mounted on a shaft 40. In a cycle of operation of the machine, eccentric 39 may be driven to its uppermost extreme position or its lowermost extreme position. Whenever link 30 is in the upper position as shown in FIG. 5, it contributes to the downward movement of the slide 22 about pivot 33. Whenever link 30 is in the lower position it contributes to upward movement of the slide 22.

The link 31 is a compound knee action link comprised of a pair of crank members 41 and 43 which are pivotally interconnected by pivot pin 42. The crank 41 is pivotally connected to the lever 23 at pivot 33. The crank 43 is urged to rock in a counterclockwise direction (FIG. 5) about its eccentric 45 by a spring 44 but is blocked from rocking in that direction by the engagement of a post 52 with the right edge (FIG. 5) of the crank 41. Thus, when in the position in FIG. 5, the cranks 41 and 43, in effect form a straight common link out of the compound link 31 so that rotation of the eccentric 45 under this condition will cause the link 31 to reciprocate in substantially a vertical direction.

With eccentric 39 in its uppermost extreme and eccentric 45 in its lowermost extreme as shown in FIG. 5, the type carrier 10 of FIG. 1 is in its lowermost printing position with the upper row of type elements carried by the carrier 10 in the printing field. In order to retract the type carrier 10 completely out of the printing field, the type carrier must be lowered to a position below its lowermost printing position. To accomplish this, a cam 55 is rotated 180 about shaft 54 from the position shown in FIG. 5, thereby driving a bell crank 56 in the counterclockwise direction about a pivot 53 and against the action of a bias spring 57. When bell crank 56 rotates counterclockwise from the position shown in FIG. 5, the lowermost end 58 of bell crank 56 moves rightwardly thereby driving a break lever 51 to the right. This breaks the knee of link 31 by rotating crank 43 clockwise about eccentric 45 against the bias of spring 44 and rotating crank 41 counterclockwise about pivot 33. This knee action movement of link 31 reduces the distance between pivot 33 and the center of eccentric 45 thus lowering slide 22 still further and with it the type carrier 10 thereby retracting the type carrier 10 out of the printing field. It can be understood that in order to retract the type carrier completely out of the printing field no matter what row of type elements is in the printing level, eccentrics 39 and 45 must be moved to the position shown in FIG. 5; and cam 55 must be rotated 180 from the position shown in FIG. 5.

In FIG. 4 a continuously-rotating main shaft 64 drives a gear 63 that is in mesh with three driven gears 60, 61, and 62; and each driven gear is rotatably mounted on its respective shaft 40, 50, and 54. Each of the driven gears 60, 61, and 62 carries the driving member of a clutch 70, 71, and 72, respectively, with it. The driven member of each clutch carries its associated eccentric 39 or 45 or cam 55 with it so that whenever one of the clutches is engaged, it rotates its associated eccentric or cam until the clutch is again disengaged thereby stopping rotation of the associated eccentric or cam. Since all three of these clutches are of the type disclosed in Patent No. 2,566,031, granted to A. N. Nilson on Aug. 28, 1951, only the clutch will be described in detail.

The driving member of the clutch 70 is driven by the continuously-rotating main shaft 64 through the driving and driven gears 63 and 60. In order to stop eccentric 39, the driven member 74 (FIG. 4) of clutch 70 can be stopped at either of two rotational positions 180 apart. The driven member 74 of clutch 70 has a bent-over portion 75 that acts as a clutch stop to engage an external stop member 76 or 91 at either of its two stop positions. When one of these stop members (76 in FIG. 4) is positioned in the path of the bent-over portion 75, the other stop member (91 in FIG. 4) is positioned out of interfering relation with this bent-over portion 75 such that the driven member 74 of the clutch 70 will either remain in the position corresponding to that interfering stop member or will engage with the driving member (rotating with gear 60) until the bent-over portion strikes the interfering stop member, stopping the driven member 74 of the clutch 70 in the desired position.

The driven member 74 of this clutch 70 also has two override notches 78 and 79 positioned on its outer periphery. Whenever the bent-over portion 75 strikes a stop member 76 or 91, the driven member of the clutch 70 continues rotating a very short distance until one of the notches (78 in FIG. 4) passes an overrun latch 77 that falls into the notch. When the driven member 74 moves this extra distance after the stop member (76 in FIG. 4) has abruptly stopped the bent-over portion 75, the connection between the driving and driven members is physically disengaged. By falling into one of the notches 78 or 79 on the outer periphery of the driven member 74 of the clutch 70 the overrun latch 77 prevents the driven member 74 of the clutch from retrogressing and thereby causing the driven member of the clutch to drag against the driving member of the clutch. This reduces the amount of friction experienced at the clutch during long periods of disengagement. The driven member 74 of the clutch 70 is thus positionable in either one or the other of two opposite rotational positions corresponding to the members 76 and 91 and carries its associated eccentric 39 (FIG. 5) with it to position this associated eccentric 39 in either one or the other of two opposite rotational positions.

Clutch 71 also has two override notches 83 and 84, that are similar to override notches 78 and 79 on clutch 70. An overrun latch 80 is biased to rotate clockwise about a post 81 by a spring 82. The overrun latch 80 bears against the rim of the driven member of clutch 71 and falls into the notch 84 or 83 after each half revolution of eccentric 45. The driven members of clutches 70, 71 and 72 have two notches corresponding to notches 78 and 79 on clutch 70. This permits each clutch to be stopped in either of its two opposite positions so as to position its associated eccentric or cam in its downward extreme or upward extreme as shown in FIG. 5.

The two stop members 76 and 91 of clutch 70 are mounted on a clutch-stop slide 90 as shown in FIG. 3. Therefore, clutch 70 is stopped in either of its two opposite positions according to the placement of clutchstop slide 90. When clutch-stop slide 90 is in its downward position as shown in FIG. 3, clutch-stop 76 is positioned in the path of bent-over portion 75 of the driven member 74 of clutch 70 (as shown in FIG. 4). Since stop member 91 is then out of the normal rotational path of bent-over portion 75, clutch 70 rotates its driven member, if necessary, so as to place bent-over portion 75 in engagement with stop member 76, thereby stopping eccentric 39 (FIG. 5) in its upward extreme position. In order to move eccentric 39 to its downward extreme position, a bell crank 92 (FIG. 3) is rotated counterclockwise about a post 93 to carry clutch-stop slide 90 to its upward position to remove stop member 76 from engagement with bent-over portion 75 of clutch 70. This permits clutch 70 to engage, carrying eccentric 39 with continuously-rotating gear 60 through one-half of a revolution until bent-over portion 75 strikes stop member 91now positioned in interfering relation with bentover portion 75--to stop eccentric 39 in its downward extreme position. A clutch-stop slide 94 similarly controls the position of eccentric 45 through clutch 71. Clutch 72, which carries cam 55 is controlled by the position of a clutch-stop slide 95.

The positions of the clutch-stop slides 90 and 94 are controlled by the code signals received by the printer. As is fully described in the above-identified Zenner patent, these input code signals are received by the printer in the form of electrical pulses and are converted to mechanical manifestations in the form of longitudinal displacements of the code bars that extend across the front of the printer. Two of these code bars, 101 and 102, are shown in FIG. 1. Code bar 102 is also shown in plan view in FIG. 6. The code bar 102 is connected to a bell crank 103 (FIG. 6) and rotates bell crank 103 about pivot 104 to move a code slide 105 to the right or left (FIG. 3). Code slide 105 is pivoted at 106 to a bell crank 92 and rotates bell crank 92 about the post 93 to position the clutch-stop 90 in one extreme position or the other according to the input code signals. Code bar 101 similarly controls the position of clutch-stop slide 94 through bellcrank 107 (FIG. 3) and connector 108. Connector 108 is operated by code bar 101 through a bell crank 109 similar to bell crank 103 of FIG. 6.

In order to retract the type carrier to a position below the printing field after a predetermined time interval during which no input code signals are received, means are provided to determine the time interval of non-receipt of characters independently of the internal timing of the printer and to trip the necessary vertical-positioning clutches in order to retract the type carrier. FIG. 2 shows a ratchet counting mechanism and an eccentric drive cam mounted on the mechanism of FIG. 3. Eccentric 115 is firmly fixed to the constantly-rotating main shaft 64 and acts as a drive cam to reciprocate a drive pawl 116. Drive pawl 116 is urged to rotate about a pivot 118 and into engagement with a ratchet wheel 117 by a bias spring 119. Pivot 118 is mounted on movable arm 120 that is in turn rotatably mounted on post 121. A spring 122 urges the movable arm 120 toward eccentric 115. Therefore, spring 122 urges drive pawl 116 to follow eccentric 115 and, as pawl 116 is reciprocated by eccentric 115, the

pawl 116 drives ratchet wheel 117 clockwise about shaft 123.

A stop pawl 124 cooperates with drive pawl 116 by engaging with and preventing retrograde movement of ratchet wheel 117. Stop pawl 124 is rotatably mounted on a fixed pivot (not shown) behind drive pawl 116 and is urged into engagement with ratchet wheel 117 by a spring 125. As main shaft '64 rotates, eccentric moves drive pawl 116 against thet urging of spring 122, to rotate ratchet wheel 117 from the position shown in FIG. 2 to the position shown in FIG. 1. Thus, with each revolution of main shaft 64, ratchet wheel 117 is advanced one tooth.

The selector mechanism of the printing machine shown in the Zenner patent mentioned above, goes through one cycle of operation each time that an input code signal is received. Attached to and carried by the selector cam sleeve 129 of the printing machine is a cam 130 (FIG. 1) that rotates a crank 131 counterclockwise about a pivot 132 against the urging of a spring 133 each time that an input code signal is received. The crank 131 is connected to a crank by a link 134, and, when crank 131 is rocked counterclockwise (FIG. 1), it moves link 134 to the left thereby rocking crank 135 clockwise together with shaft 136 to which crank 135 is fixed. Shaft 136 extends across the width of the machine and carries with it an arm 137. Therefore, each time the selector mechanism receives an input code signal, arm 137 is rotated clockwise. Arm 137 has a bent-over portion 138 which extends across pawls 116 and 124; and when it is rocked clockwise (FIGS. 1 and 2), it disengages drive pawl 116 and stop pawl 124 from the ratchet wheel 117 against the action of bias springs 119 and 125, respectively.

A bail 140 (FIG. 2) is attached to the back of and rotates with ratchet wheel 117. A spring 141 is attached to bail 140 and biases ratchet wheel 117 to rock in the counterclockwise direction. Whenever drive pawl 116 and stop pawl 124 are disengaged from ratchet wheel 117, upon receipt of an input code signal, ratchet wheel 117 is reset to its initial condition by the spring 141. A stop 142 cooperates with a reset tooth 139 on ratchet wheel 117 to determine the initial condition of ratchet wheel 117. Whenever arm 137 disengages pawls 116 and 124 from ratchet wheel 117, spring 141 rocks ratchet wheel 117 counterclockwise until tooth 139 on ratchet wheel 117 strikes stop 142. A slot 148 formed in stop 142 permits stop 142 to be clamped in place by a screw 147 anywhere along slot 148 in order to vary the initial position of ratchet wheel 117.

If input code signals are received steadily the ratchet wheel 117 is reset by the arm 137 during each cycle of the machine and therefore does not move significantly from the position shown in FIG. 2. However, during any non-receipt of input code, cam 130 is not rotated, and therefore, arm 137 does not reset ratchet wheel 117. The main shaft 64 continues to rotate, however, and operates the pawl 116 to wind ratchet wheel 117 from the position shown in FIG. 2 to that shown in FIG. 1. As ratchet wheel 117 is rotated clockwise by pawl 116, a prong 143 on bail 140 engages a tab 144 on a link 145 that is rotatably mounted on a post 146 which is in turn mounted on a trip slide 150. A spring 151 urges link 145 to rotate clockwise about post 146 thereby positioning a tab 152 on link 145 in engagement with a post 153 on trip slide 150.

As ratchet wheel 117 is rotated clockwise and prong 143 engages tab 144, the prong 143 tends to rotate link 145 counterclockwise (FIG. 1) about post 146; but spring 151 exerts suflicient force upon link 145 to prevent link 145 from rotating. Instead, prong 143 moves the entire trip slide to the right against the action of a spring 154 which tends to hold the slide 150 in the position shown in FIG. 2. When trip slide 150 moves to the right, an abutting portion 156 (FIGS. 1 and 3) on slide 150 strikes bell crank 103 and connector 108 (FIG. 3) pushing them to the right as slide 150 moves to the right thereby resetting code bars 101 and 102 to the appropriate position to select the lowermost type carrier printing position. If the type carrier is already in its lowermost printing position, no change occurs; but if it is not, clutches 70 and 71 are thus reset to select the lowermost type-carrier printing position. In addition, an extension 155 (FIG. 3) on trip slide 150 which is connected to clutch stop slide 95 by pin 157 moves clutch stop slide 95 to its rightmost position (FIG. 3). This trips clutch 72 thereby rota-ting cam 55 180 from the position shown in FIG. 5 which in turn breaks the knee of ink 31 to lower the type carrier completely out of the printing field. The sole purpose of link 145 and spring 151 is to provide a yield in the driving of trip slide 150 by prong 143 to prevent breakage of parts in the event that prong 143 attempts to move trip slide 150 to the right to reset code bars 101 and 102 before these code bars are fully released by their drive means (as shown in the above mentioned patent to Zenner).

After the type carrier has been fully retracted out of the printing field it stays retracted until the receipt of input code signals is again commenced. A toothless portion 158 (FIG. 1) is provided on ratchet wheel 117 between the last driving tooth 159 and reset tooth 139. When the type carrier has been fully retracted out of the printing field and no input signal is received, the main shaft 64 continues to rotate cam 115 and thereby reciprocate drive pawl 116. However, due to the toothless portion 158 on ratchet wheel 117 this action does not rotate the ratchet wheel 117 further.

The first input code signal operates through arm 137 to disable the pawls 116 and 124 and thereby permits spring 141 to reset ratchet wheel 117 to its initial position as determined by the position of adjustable stop 142. The position of stop 142 determines how far ratchet wheel 117 must be wound by pawl 116 and eccentric 115 before retraction of type carrier occurs thereby, fixing the delay between receipt of the last character and retraction of the type carrier out of the printing field. When prong 143 moves away from tab 144, spring 154 moves trip slide 150 to the left (FIG. 1) freeing code bars 101 and 102 so that they may be set according to the input code signal.

When trip slide 150 moves to the left, it carries clutchstop slide 95 to the left thereby tripping the clutch 72 for a cycle of one-half revolution to return cam 55 to the position shown in FIG. 5. This permits spring 44 to straighten link 31 which in turn moves the type carrier 10 into the lowermost printing position. At this time code bars 101 and 102 can cause the vertical positioning mechanism to move the type carrier to whatever vertical position is dictated by the input code signal.

In order to fully expose the last-printed characters whenever the type carrier is retracted out of the printing field, the ink ribbon must also be lowered out of the printing field.

What is claimed is:

1. A printing telegraph apparatus comprising:

a continuously rotating main shaft;

means driven by the main shaft for receiving telegraph signals;

a type carrier having a plurality of rows of type elements supported thereon;

carrier operating means driven by the main shaft and controlled by signals received by said receiving means for moving the type carrier in a positive mechanical manner in a direction perpendicular to the rows to bring a selected row into a printing position;

means for counting the number of revolutions of the main shaft occurring after receipt of a character by the receiving means, and

means responsive to a predetermined count by the counting means for operating the carrier operating means and thereby retracting the type carrier into a position to expose to view the previously printed characters.

2. In an aggregate-motion printer:

a type carrier having a plurality of rows of type elements supported thereon;

a number of two-stop clutches, the number being greater than the square root of the number of rows of type faces on the type carrier;

a number of cams, each associated with and driven by a two-stop clutch;

an aggregate-motion lever system driven by the cams for moving the type carrier in a direction perpendicular to the rows to bring a selected row to the printing position, and

means for simultaneously controlling all of the twostop clutches and thereby causing the aggregate-motion lever system to move the type carrier away from the printing position into a non-printing position.

3. The apparatus according to claim 1 further including means responsive to receipt of a signal by the receiving means for resetting the counter and thereby preventing operation of the carrier operating means by the count responsive means.

4. The apparatus according to claim 1 wherein the counting means includes a pawl and ratchet counter and wherein the resetting means includes means for disengaging the pawl from the ratchet thereby resetting the counter.

5. The apparatus according to claim 2 wherein the carrier operating means includes knee action means and means for normally maintaining the knee action means in a straight condition and wherein the count responsive means includes means for breaking the knee of the knee action means.

6. The telegraph printer according to claim 2 wherein the aggregate-motion system includes a lever for moving the type carrier and a knee action link connected between one of the clutches and the lever and further including means connected to another clutch is for operating the knee action portion of the knee action link.

7. The telegraph printer according to claim 6 further including:

signal receiving means, and

means responsive to the signal receiving means for controlling the position of all but one of the two-stop clutches,

and wherein the remaining two-stop clutch operates the knee action portion of the knee action link.

8. The telegraph printer according to claim 7 further including means for measuring intervals of non-receipt of characters by the signal receiving means and for operating the means for controlling all of the clutches whenever the interval exceeds a predetermined period of time.

9. A printing telegraph mechanism of the type including a type carrier, a vertical positioning mechanism for placing the type carrier in various vertical positions, means for receiving signals representative of characters to be printed and a constantly operating drive mechanism; the combination with the vertical positioning mechanism of:

a counter;

means responsive to each operation of the drive mechanism for advancing the counter, means responsive to receipt of signals by the signal receiving means for resetting the counter, and

means responsive to a predetermined amount of advance of the counter for actuating the vertical positioning mechanism thereby positioning the type carrier in a pre-selected position.

10. The combination according to claim 9 wherein the vertical positioning mechanism includes a type carrier position control member which is nonresponsive to signals received by the signal receiving means and wherein the counter responsive means includes means for operating the nonresponsive position control member and thereby moving the type carrier to a non-printing position.

11. The combination according to claim 9 wherein the counter includes a ratchet wheel, a drive pawl for advancing the ratchet wheel and a check pawl for retaining the wheel in an advance position and wherein the means for resetting the counter disengages both of the pawls from the ratchet wheel.

12. The combination according to claim 11 wherein the means for advancing the counter includes a cam driven by the drive mechanism of the telegraph mechanism and mounted in engagement with the drive pawl for advancing the ratchet wheel in response to operation of the drive mechanism.

13. In a printing telegraph mechanism of the type including a cyclically operating drive mechanism and means for receiving characters to be printed, the subcombination of:

a pawl,

a ratchet mounted for movement by the pawl,

means driven by the drive mechanism during each cycle thereof for operating the pawl and thereby moving the ratchet, means responsive to a predetermined amount of movement of the ratchet for producing an output, and

means responsive to receipt of a character by the receiving means for resetting the ratchet thereby preventing production of the output.

14. The subcombination according to claim 13 wherein the telegraph mechanism includes a frame, the ratchet is a ratchet wheel rotatably mounted on the frame, the pawl is slidably mounted on the frame in engagement with the ratchet wheel and wherein the means for operating the pawl includes a cam mounted on the drive mechanism of the telegraph mechanism and continuously rotated thereby and positioned in engagement with the pawl.

15. The combination according to claim 13 further including a spring for returning the ratchet from an advance position, means Iimiting return movement of the ratchet and a check pawl for retaining the ratchet in an advanced position and wherein the resetting means includes means for disengaging both the pawl and the check pawl from the ratchet thereby allowing the spring to return the ratchet.

'16. The combination according to claim 13 wherein the means for producing an output includes a tab mounted for movement by the ratchet and a lever positioned on the telegraph mechansim for actuation by the tab upon a predetermined amount of advance of the ratchet.

17. In a printing mechanism of the type including a type carrier and a type carrier positioning mechanism, a device for exposing copy printed by the printing mechanism including:

a knee action link forming part of the type carrier positioning mechanism,

means for retaining the knee action link in a straight condition during printing operations of the printing mechanism, and

means for breaking the knee action link thereby moving the type carrier to a non-printing position.

18. The device according to claim 17 further including means for receiving signals and for activating the type carrier positioning mechanism in response thereto, means for measuring the period of time which has elapsed after the receipt of a signal by the signal receiving means, and means responsive to measurement by the measuring means of more than a predetermined amount of time for actuating the knee action link breaking means.

19. The device according to claim 18 wherein the printing mechanism includes a continuously rotating drive shaft and wherein the knee action link breaking means includes a lever connected to the knee action link, a cam mounted in engagement with the lever for rotating movement to drive the lever in a link breaking direction, a clutch for coupling the cam to the drive shaft and wherein the means responsive to the measuring means actuates the knee action link breaking means by engaging the clutch.

20. The device according to claim 19 wherein the elapsed time measuring means includes a digital counter driven by the drive shaft and advanced thereby one digit for each rotation of the shaft and means responsive to receipt of a signal by the signal receiving means for resetting the counter.

Refereuces Cited UNITED STATES PATENTS 2,505,729 4/1950 Zenner a- 178-25 2,566,031 8/1951 Nilson 192-26 2,773,931 12/1956 Kleinschmidt et al. 178-23 2,843,667 7/ 1958 Slayton 178-25 2,861,125 11/1958 Griffith 178-33 2,906,821 9/1959 Griffith 178-34 2,963,547 12/1960 Madsen 178-23 3,014,094 12/1961 Nordin 178-23 3,128,341 4/1964 Madsen 178-25 3,201,514 8/1965 Kleinschmidt 178-24 THOMAS A. ROBINSON, Primary Examiner US. Cl. X.R.

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