Typewriter Dual Feed Apparatus

Abstract

A typewriter capable of conventional paper feed downward and to the rear of the platen cylinder or upward from below the platen cylinder as for computer paper. A single arm and linkage assembly provides for roller release for conventional feed in a first position and for retraction of the entire platen assembly for computer paper feed in a second position. A sprocket drive operating in conjunction with the platen cylinder for computer paper is provided.

Description

BACKGROUND OF THE INVENTION

The invention relates to typewriters and more particularly to a typewriter capable of two types of paper feeds and drives: conventional typewriter feed wherein the paper is fed from the rear of the platen cylinder, down and around a significant portion of the cylinder and computer paper feed wherein the paper is fed upwardly from below the platen. In the latter instance only a small portion of the cylinder surface is used, thus simulating a flat platen.

It has been found that the conventional typewriter feed is unsuited to computer paper feed because of the great thickness of most computer paper (usually five or six sheets in addition to carbon sheets). The radius of curvature of the platen cylinder is just too small to successfully handle such a load. Thus the typical typewriter for computer applications provides for an upward feed with the paper passing a flat platen. Means for driving the paper or pulling it upward is generally located above the platen. Heretofore it has been considered a problem to incorporate both types of feed in a single unit chiefly because of the mechanical difficulties in providing not only for insertion, holding, and release of the paper by both approaches but also the problem of driving the paper in both modes. Thus, apparently conflicting requirements must be provided for: a movement of the platen assembly horizontally to create a larger passageway for the intial insertion of computer paper and the retraction of pressure rollers that normally engage the platen cylinder for the insertion of paper for the conventional feed; and paper drive by means of a rotating platen cylinder and by a sprocket drive or other means for driving paper past a flat platen.

SUMMARY OF THE INVENTION

A typewriter has standard features including an endless chain of printing characters, hammers for striking the characters against a platen, a keyboard, adjustments for line spacing and the like. Two methods of paper feed are possible: in the conventional method of feed, the paper is inserted from the rear and downardly behind the platen cylinder. A pair of retractable roller sets provide engagement between the paper and cylinder as it wraps around a portion of the cylinder. A lever arm is linked to the retractable rollers to permit them to be disengaged from the cylinder to ease insertion of paper.

In the second paper feed method, heavy thicknesses of paper such as mutilayered computer paper is fed upward from below and in front of the platen cylinder. The cylinder is used effectively as though it were a flat platen. In order to insert the paper, the heretofore mentioned lever arm is moved to a more extreme position whereby the linkage moves the platen assembly horizontally to provide a wider passageway for insertion of the paper thickness. A sprocket drive having a chain and pulley drive from the platen cylinder pulls the perforated computer paper upward thus permitting the line feed caused by cylinder rotation to also drive the sprocket mechanism.

These and other objects and advantages of the present invention will become apparent from a reading of the following description and claims in the light of the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a typewriter embodying aspects of the present invention.

FIG. 2 is a cross-sectional view of FIG. 1 along section line 2--2.

FIG. 3 is a cutaway side view of a portion of the typewriter showing the roller release linkage mechanism.

FIG. 4 is a cutaway side view of a portion of the typewriter showing the platen release linkage mechanism.

FIG. 5 is a cutaway side view of the tractor paper drive.

FIG. 6 is a cross-sectional view of FIG. 5 taken along section line 6--6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A general understanding of the double feed typewriter of the present invention will be facilitated by reference now to FIGS. 1 and 2. FIG. 2 is a cross-section of FIG. 1 along section line 2--2. For greater clarity, the sprocket drive for computer type paper is not shown in FIG. 1. The typewriter is shown on a standard 1 and includes many conventional features including a case 2, a keyboard 4, a cylindrical platen 6 mounted on a shaft 7 having control knobs 8 at each end, retractable bar and paper guide rollers 10 and levers 12 for adjusting to paper thickness and for selecting the number of spaces between lines. Lever 14 controls the release of rollers 16 and 18 and the release of platen 6 in order for paper to be inserted in the machine. The function of lever 14 is an important feature of the invention and will be described in greater detail with reference to FIGS. 3 and 4. A chain printer mechanism 20 is mounted adjacent to the face of platen 6 for typing characters on paper between the platen 6 and the printer mechanism 20. The details of the chain printer mechanism form no part of the present invention and are the subject of copending applications of George W. Bowers, Jr., et al, Ser. No. 21,464, filed Mar. 20, 1970, and of Ronald T. Albo, et al, Ser. No. 21,436, filed Mar. 20, 1970, now U.S. Pat. No. 3,656,425 issued Apr. 18, 1972. A cross-section of the type chain 22 is shown in FIG. 2. A hammer 24 strikes the type character on the chain 22 to drive the character against platen 6 to form an impression.

Two possible paper feeds are shown in FIG. 2. A conventional feed is accomplished by inserting a piece of paper 25 between the rear of platen 6 and retractable rollers 16 and 18. As lever 14 is pulled partially forward, rollers 16 and 18 retract thus facilitating insertion. A second feed, for computer paper 32 is made at opening 26 at the bottom rear of case 2. Paper guides 28 and 30 guide the computer paper 32 along a curved path upward to the platen 6. To permit easy insertion of the computer paper 32, lever 14 is pulled forward to its extreme position thus moving the entire platen assembly 36 (shown in FIG. 4) to the rear slightly away from vertical spring guide 34. A sprocket drive assembly 38 is employed when using computer paper 32 in the typewriter unit. The sprocket drive assembly 38 is illustrated in greater detail in FIGS. 5 and 6 and includes generally an assembly operating with the turning of cylindrical platen 6 to engage the sprocket holes 33 on the edges of the computer paper 32 to pull it upward through a sprocket belt sub-assembly 40. The sprocket drive assembly 38 is of the type commercially available that can be attached to and detached from a conventional typewriter.

The roller 16 and 18 release function of lever 14 is best understood by reference now to FIG. 3. Section 101 is a fixed member attached to case 2. In the normal rearward position of lever 14, rollers 16 and 18 engage cylindrical platen 6 and the platen assembly 36 is spaced close to paper guide 34. When lever 14 is moved forward or counterclockwise it pivots at pin 104. Initially, the lever 14 is moved about 10.degree. to position 14'. A second arm or portion 106 of lever 14 is integral with lever 14 and moves at the same time to position 106'. As arm 106 drops down a linkage 108 that is pivoted to arm 106 at pin 107 and to a coupling member 110 at pivot pin 109 is urged downward. Coupling member 110 is fixed to a curved arm 112 and both pivot at the point of connection on a pin 111. Thus as linkage 108 moves downward, arm 112 pivots clockwise on the axis of pin 111 to position 112' and the roller 16 mounted at the end of arm 112 is disengaged from the cylindrical platen 6. The other end of arm 112 is forked shaped to engage a finger 117 on a second curved arm 118 that is pivotally mounted on a pin 116. Thus as arm 112 rotates clockwise, arm 118 will rotate counterclockwise on the axis of pin 116 to position 118' thus disengaging from the platen 6 the roller 18 located at the end of arm 118. A tension spring 122 is connected from member 101 above roller 18 at point at 127a to a hole 125 in the side of coupling member 110 to thereby assure proper engagement of the rollers 16 and 18 when lever 14 is in its closed rearward position. Pivot pin 104 is mounted on the case 2 of the typewriter while pivot pins 111 and 116 are mounted between a pair of end plates 123 (shown in FIG. 4) at opposite ends of the platen assembly 36. The end plates 123 are mounted on a pivot shaft 125 (shown in FIG. 4) which is in turn mounted on the case 2 of the typewriter.

Thus far lever 14 has not been moved to its most forward position at 14". FIG. 4 illustrates the action of lever 14 to effect movement of the entire platen assembly 36 to achieve insertion of computer paper 32. The platen assembly 36 is pivotally mounted on shaft 125 so as to move horizontally upon control of linkage 42. Linkage 42 engages pin 107 of arm 106 through a lost motion channel 44 and is pivoted to assembly 36 by a pin 46 mounted in end wall 123. Thus for disengagement of only the rollers 16 and 18, lever 14 is pulled only to the point where pin 107 has reached the right end of channel 44 at 14'. Up to this point pin 46 and assembly 36 have not pivoted about shaft 125. Upon pulling lever 14 forward beyond this point to position 14", arm 106 rotates to position 106" causing pin 107 at position 107" in FIG. 4 to pull on the end of slot 44 thereby causing linkage 42 to exert a rightward pull on assembly 36 through pin 46 thus moving the assembly 36 away from paper guide 34 by rotating it clockwise on shaft 124. The platen 6 and shaft 7 move to positions 6' and 7' along with the platen assembly 36. A conventional platen lock 127 also moves integrally with the platen assembly 36 to position 127'.

Referring now to FIGS. 5 and 6, details of the sprocket drive assembly 38 are shown. The assembly 38 is mounted between a pair of end frame pieces 39, one of which is shown in the drawing. Computer paper 32 is shown curving upward (paper guides 28 and 30 not shown) past paper guide spring 34 which applies frictional drag to the paper 32 and over cylindrical platen 6. Paper 32 has holes 33 adapted for sprocket engagement. Ratchet teeth 55 for discrete line control as in conventional typewriters are shown at the end of platen 6 in FIG. 5. The platen 6 is driven by the action of arm 49 against teeth 55. The arm 49 is linked to a rocker arm 51, that rocks on pivot shaft 57, and to eccentric drive wheel 53. Between teeth 55 and the platen cylinder 6 is a second set of teeth 50 that engage an endless loop chain belt 52. Belt 52 forms a generally triangular configuration as it wraps around toothed pulleys 54 and 56 and a doubled toothed pulley 58. Pulley 58 has a first set of teeth 60 that engages belt 52 and a second set of teeth 62 that engages sprocket drive sub-assembly 40. Teeth 50 on platen 6 engage the belt 52 and provide drive for the belt 52 thus causing pulley 58 to move in step with the platen 6. The second set of teeth 62 on the pulley 58 drives the sprocket sub-assembly 40 by meshing with the teeth 64 on a drive wheel 66 that drives a sprocket belt 68 (shown in FIG. 6). A removable paper guide 72 having a handle 74 assures engagement of the paper 32 and sprocket drive belt 68.

Claims

We claim:

1. In a typewriter having a case and a platen assembly including a rotatably mounted cylindrical platen, the improvement which comprises

platen assembly support means attached to the case,

a platen assembly rotatably mounted on said support means,

a lever rotatably mounted on a pivot extending from the case,

a first linking member linking the platen assembly to said pivoted lever,

a lost motion channel in said first linking member such that the lever must be moved an appreciable distance before rotation of the platen assembly is initiated,

roller means, for holding paper against the platen, mounted on a curved arm,

a pin extending from the case and penetrating the cruved arm to permit rotation of the curved arm about the pin, and

a second linking member linking the curved arm to said pivoted lever, said second linking member being attached to the lever by a pin, whereby movement of the lever moves the roller means away from the platen before rotation of the platen assembly is initiated.