US2162427A - Printing mechanism - Google Patents

Description

June 13, 1939. L FROYD 2,162,427

PRINTING MECHANISM Filed April 20, 1956 2 Sheets-Sheet l L. W. FROYD PRINTING MECHANISM June 13, 1939.

Filed April 20, 1936 2 Sheets-Sheet 2 Patented June 13, 1939 PATENT OFFICE PRINTING MECHANISM Lawrence Wilbur Froyd, Arlington, Va., assignor to Albert Falk Doig, Washington, D.

Application April 20, 1936,- Serial No. 75,456

Claims.

This invention relates to improvements in printing mechanisms of the multigraphing type, and more particularly to a method and apparatus for inking such mechanisms while in operation.

5 In printing with duplicating machines of the multigraphing type, it is customary to impart impressions. of characters or type carried by a printing cylinder of the machine to the surface to be printed through a transfer ink ribbon mounted over the characters or type on the cylinder. As each duplicate is produced, the transfer ink ribbon is advanced over the character or type surface with a step-by-step movement. It will therefore be apparent that, as impressions are produced, the ink content of the ribbon will be rapidly depleted, necessitating frequent removal of the ribbon to replenish its ink content. It will be apparent further that, as the transfer ribbon advances over the type surface, the ink content of the ribbon will gradually decrease to a minimum toward the rear end of the ribbon. As a result thereof, the printed impressions obtained will be of varying intensity and the printing of the introductory area of the impression will be darker than that of the closing area, thereby destroying the similarity of the printed letter to an actual typewritten letter.

Attempts have been made to overcome these defects by inking the ribbon while in operation.

All such attempts have heretofore proved unsuccessful. Workers in this art have employed stationary ribbons and have applied ink directly to the ribbon surface. This method appears to be objectionable in that the ribbonwear is concentrated in a localized area, resulting in blurred printing and a material decrease of the life of the ribbon. Other methods have contemplated the application of a surplus of ink directly to the inking ribbon and subsequently removing the surplus by passing the ribbon under a wiper. These methods have likewise proved unsuccessful in that the wiper rapidly becomes saturated with ink, resulting in a gathering of ink between the lines, of type causing interlinear streaks on the printed surface. The use of wipers is further objectionable in that repeated contacts of the ribbon and wiper tend to wear the ribbon material resulting in blurred printing and decreased ribbon life.

All previous attempts in this art to supply ink directly to the moving ribbon of the multigraphing type of printing mechanism while the machine is in operation, have been unsuccessful. Such failures may be attributed to the fact that heretofore operators have permitted the transfer ribbon to advance when it is under the pressure of the inking rollers. This necessarily results in stretching the ribbon each time an impression is obtained. As a result, the ribbon is caused to lose shape and wear out rapidly. Such '5 methods further resulted in an uneven applica tion of ink.

The present invention contemplates an improvement for overcoming the above objections and comprises a cam attachment as a substitute 10 for the present eccentric employed in the standard multigraphing machine, which cam alters the sequence of operation of the present machine and permits re-inking of the ribbon while the machine is in operation, insuring a uniform disl5 tribution of ink throughout the ribbon for each individual printing with a minimum amount of ribbon wear.

It is accordingly an object of this invention to provide a method and apparatus for re-inking 20 the movable transfer ribbon of a printing mechanism while the machine is in operation in a manner to elfect a uniform distribution of ink in the ribbon.

It is further an object of this invention to 25 provide a method and apparatus for reinking the movable transfer ribbon. of a printing mechanism while the machine is in operation whereby to obtain impressions of uniform intensity,

It is further an object of this invention to provide a cam mechanism for controlling the advance of the transfer ribbon of a duplicating machine and effecting movement of the transfer ribbon when the same is out of contact with the inking attachment and the platen. 35

These and other objects will readily become apparent from the specification which follows when considered with the accompanying drawings which show the preferred form of my invention. gm

Reference is made to the accompanying draw? ings, of which- Figure 1 is an end elevation of a duplicating machine of the multigraphing type;

Fig. 2 is a partial vertical section on line 2-2 45 of Fig. 1, showing a ribbon feeding mechanism;

Fig. 3 is an end elevation of the inner face of a feeding. cam and supporting plate therefor shown in section in Fig. 2;

Figs. 4 to 6 are diagrammatic views illustrat- 5O ing the sequence of operation embodied in my invention; and

Fig. 7 shows a portion of a ribbon feeding mechanism.

The printing mechanism disclosed in Fig. l is 55 of conventional structure and includes the usual printing cylinder I, cylinder supports 2, side plates 3, transfer ink ribbon 4 and platen 5. The cylinder may be rotated in a counter-clockwise direction, as seen in Fig. 1, by means of the crank 6 or other suitable driving means. Ink may be applied to the transfer ribbon by an ink fountain attachment 1 of the usual type. The particular inker disclosed is the seven roller type and comprises an ink fountain 8, transfer roll 9 and intermediate rolls l0 and Ink is applied to the transfer ribbon 4 by the transfer roll 9.

According to my invention, the ink is applied to the transfer ribbon while the ribbon is stationary with respect to the printing cylinder. It is impossible to obtain this result when the standard eccentric and eccentric strap, or any-modification thereof, is employed, in view of the fact that the eccentric and eccentric strap advance the transfer ribbon continuously through 180 degrees of the rotation of the printing cylinder. To accomplish the desired result, I employ a cam attachment in place of the usual eccentric to control the ribbon feeding mechanism. A preferred form of cam is shown in detail in Figs. 2 and 3 and comprises a plate 12 provided with a recessed track or cam slot Hi. The plate I2 is secured to the side plate 3 and the cam slot is adapted to receive a roller follower l4. As shown in Fig. 2, the roller I4 is secured on the free end of apin I5, which, in turn, is secured firmly to a radially movable main operating bar It. The bar i6 is constructed and operates similarly to the radial bar shown in Fig. 5 of Patent 1,807,322. The bar I6 is forked at its lower end to straddle the shaft '11 to be guided thereby. The upper end of the bar It carries a perforated lug l8 slidably mounted on a radial pin l9 carried by the drum spider 20.

According to the prior art, as shown by Patent 1,807,322, an eccentric strap such as 8| in that patent is utilized to cause the operating pin to move in and out radially. Obviously, the movement of an eccentric strap about an eccentric is exactly similar on either side of its center line, and such an eccentric control can only move such a bar 85 radially outwardly uniformly during one-half rotation of the eccentric and radially inwardly uniformly during the following half rotation of the eccentric. When such an eccentric is used, it is necessary to rotate the drum degrees to move the eccentric strap its full throw inwardly, during which complete period, the ribbon is uniformly advanced one step.

Fig. '7 shows the details of the ribbon feeding mechanism according to the prior art. The control bar Hi atits lower end is formed in a fork 2! which straddles the shaft ll. A pair of dogs 22 are pivotally carried on bar IS in position to engage a pair of ribbon drums. These drums are rotated by the dogs 22. As shown, when the left hand dog is moved downwardly by pin I5 and bar l6, it will engage teeth'23 secured to one end of the ribbon drum to rotate the latter to feed the ribbon 4.

The pitch surface of the cam slot is designed so that the total fall required to advance the transfer ribbon the required amount occurs within an arc of approximately 83 degrees, so situated on the cam plate l2 that such advance of the transfer ribbon takes place when the ribbon is entirely out of contact with the inking "rolls and the platen. The remaining 277 degrees of the 'most point of the cam slot.

are encompassed by the cam slot is adapted to cause the necessary rise of the roller follower to place the ribbon advancing mechanism in proper engagement with the ribbon take-up and feed spools, preparatory to advancing the same.

Figs. 4 to 6 represent, in diagrammatic form, three successive relative positions of the cam slot, inking roller, printing type and roller follower. In these figures, the type surface 2| of the cylinder has been represented as rotating in a clockwise direction. In Fig. 4, a printing oper ation is indicated as commencing, the leading edge of the type surface having just engaged the platen roller 5. The roller follower I4, at this instant is positioned in and at the lower- In Fig. 5, the type surface and adjacent transfer ribbon have moved a short distance under the inking roller 9 and the impression is almost completed. The roller M has moved through the same are as has the surface 2 I, but the cam slot has caused the roller to move a short distance away from the axis of the drum. Continued rotation of the drum will position the parts as shown in Fig. 6 wherein the inking operation has just been completed. At this instant, the roller M has reached the highest point in the cam slot and the roller is now positioned at its maximum distance from the drum center.

In operation, the cylinder is rotated by the handle 6 and paper is fed between the cylinder I and platen 5. The position of the roller follower at the instant the printing operation begins is indicated schematically in Fig. 4. As the cylinder I continues to rotate, the roller follower advances in the cam slot causing the bar [6 to move gradually away from the drum center. Continuing the rotation of the printing cylinder, the type surface and transfer ribbon start to pass under the inking roller as indicated at Fig. 5. Further rotation of the cylinder completes printing and continues the inking of the transfer ribbon. When, by rotation of the cylinder, the transfer ribbon covering the type surface has passed beneath the inking roller, the roller follower will have reached the highest point or peak of the rise of the cam slot as indicated at Fig. 6. At this instant, the type surface and transfer ribbon have passed out of contact with the inking roller. der through only about 83 degrees causes the roller follower to move to its original innermost position indicated in Fig. 4, thereby advancing the ribbon one step to present a uniformly inked ribbon area to the type surface.

It will be apparent from the foregoing that the transfer ribbon will be reinked while the printing machine is in operation in such a manner as to effect a uniform distribution of ink on the ribbon for each impression, thereby obtaining copies of constant intensity without additional ribbon wear.

What I claim is:

1. In a multigraphing machine, a drum, means to rotate the drum, said drum having a printing form on the face thereof, a platen with which the printing form may coact, an inking ribbon in contact with the printing form, an inking roller positioned to engage said ribbon after it has passed from under said platen, a stationary drum support, cooperating means on said drum and support for sliding said ribbon over the face of said printing form, and being operable in timed relation to slide the ribbon onlyafter the printing form has been moved under said roller to a posi- Further rotation of the cylinv,

tion in advance of said roller, said means comprising an endless cam member and a member in engagement therewith, one of said members being movable with respect to the other upon movement of the drum.

2. In a multigraphing machine,'a drum means to rotate the drum, said drum having a printing form on the face thereof, a platen with which the printing form may coact, an inking ribbon in contact with the printing form, an inking roller positioned to engage said ribbon after it has passed under said platen, a support for the drum, said drum being movable with respect to the sup,- port, said plate being provided with an endless cam surface, an operating bar slidably mounted for radial movement on said drum, a pin extending from said bar and being positioned to engage said surface, means operably responsive to movement of said bar radially inwardly to slide said ribbon over the face of said printing form, said cam surface being formed and positioned to move said pin and bar only after the printing form has been moved from under the inking roller and before the printing form has been moved to engage said platen.

3. In a multigraphing machine, a drum, an inking ribbon associated with said drum, means to rotate the drum, a support for the drum, said drum being movable with respect to the support, said support being provided with an endless cam surface, an operating bar slidably mounted for radial movement on said drum, a pin extending from said bar and being positioned to engage said surface, means operably responsive to movement of said bar and pin for feeding said ribbon over the drum.

4. A ribbon feed control for a multigraphing machine comprising a plate, said plate being provided with an endless cam surface, a drum, a ribbon associated with the drum, means to rotate said drum, a pin supported by said drum in position to engage said surface and being movable by said surface during rotation of the drum, and means responsive to movement of said pin for feeding the ribbon over the drum.

5. In a multigraphing machine comprising a rotary drum provided with a printing form and a ribbon in contact therewith, a platen associated with said drum, said drum and formlbeing rotatable through a portion of one revolution to cooperate with said platen and complete an impression, means to apply ink to said ribbon throughout another portion of the revolution, a stationary drum support, cooperating means on said drum and support for feeding said ribbon over the drum after application of the ink and prior to engagement of the drum and printing form with the platen, said means comprising an endless cam member and a pin member in engagement therewith, one of said members being mounted on the drum support, the other member being mounted on the drum, and means operably responsive to movement of the last-named member for feeding said ribbon over the drum.

LAWRENCE W'ILBUR FROYD.

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