US3888339A - Impression control mechanism for a typewriter or similar machine - Google Patents

Abstract

Impression control mechanism for regulating the impact velocity of a single element type carrier against a platen. The support for the type carrier is driven about a pivot by a cam to effect printing. The cam acts through one end of a control lever which end in turn supports and acts directly on a pin located on and spaced from the type carrier support pivot. The control lever is pivoted at its opposite end to an adjusting lever which is itself pivoted to move the control lever pivot and through its end acting on the pin to shift the type carrier support about its pivot establishing the rest position of the type carrier relative to the platen thereby determining the impact velocity of the type carrier.

Description

United States Patent 1 Nowak et al.

[ IMPRESSION CONTROL MECHANISM FOR A TYPEWRITER OR SIMILAR MACHINE [75] Inventors: Gerald Nowak, Bienrode; Herbert Decker, Lauf, both of Germany [73] Assignee: Triumph Werke Nurnberg A. G.,

Nurnberg, Germany [22] Filed: Mar. 1, 1974 [21] Appl. No.1 447,229

Related US. Application Data [63] Continuation of Ser, No, 277,591, Aug 3, 1972,

abandoned.

[30] Foreign Application Priority Data Aug. 7, 1971 Germany 2139650 [52] [1.8. Cl 197/55; 197/18 [51] Int. Cl B4lj H60 [53] Field of Search 74/53, 539; 197/16, 17, 197/55, 18

[56] References Cited UNITED STATES PATENTS 213,553 3/1879 Eastwood 74/569 2,879,876 3/1959 Palmer et a1 H 197/16 2,926,768 3/1960 Becker et a1 197/55 X 1 June 10, 1975 3,263,511 8/1966 Wellstein 74/53 3,330,398 7/1967 Hylan 197/16 ()THER PUBLlCATlONS IBM Customer Engineering Reference Manual" for Selectric l/O Keyboard Printer, pgs. (2-40 2-42).

Primary ExaminerEdgar S. Burr Assistant Examiner--Paul .1 Hirsch Attorney, Agent, or Firm-Joseph R. Spalla 57] ABSTRACT Impression control mechanism for regulating the impact velocity of a single element type carrier against a platen. The support for the type carrier is driven about a pivot by a cam to effect printing. The cam acts through one end of a control lever which end in turn supports and acts directly on a pin located on and spaced from the type carrier support pivot. The control lever is pivoted at its opposite end to an adjusting lever which is itself pivoted to move the control lever pivot and through its end acting on the pin to shift the type carrier support about its pivot establishing the rest position of the type carrier relative to the platen thereby determining the impact velocity of the type carrier.

3 Claims, 2 Drawing Figures IMPRESSION CONTROL MECHANISM FOR A TYPEWRITER OR SIMILAR MACHINE This is a continuation of copending U.S. application Ser. No. 277,591, tiled Aug. 3, 1972, now abandoned.

This invention relates to an impression control mechanism in a power driven typewriter or similar business machine for regulating the intensity with which a type element impacts against a recording medium, and more particularly to an impression control mechanism for regulating the impact intensity ofa single element typewriter in which the type element or carrier is mounted on a carriage for movement past the recording medium.

In a typewriter or similar business machine in which printing is effected by a type element or type character impacting against the recording medium, an impression control mechanism is usually provided to control the intensity with which the type character strikes against the recording medium so as to control the density or outline of the character thus formed on the recording medium. In a conventional single element typewriter all of the type characters are carried on a generally sphere-like member which undergoes a common stroke for each character to be printed, and accordingly only a single impression control mechanism is necessary to vary the intensity of impact resulting from the single printing stroke. However, since the printing element is carried along a line of type by a carriage during successive printing operations, it is necessary for the impression control mechansim to likewise be mounted on the carriage for movement with the single element printer.

In the typical single element printer, the type element is mounted on a pivotally supported rocker, and printing is effected by pivoting the rocker to move the type element from a normal position to a printing position where it impacts against a paper platen. Usually, this is accomplished by means of a cam acting on the rocker through a cam follower which is pivotally supported with one end of the cam follower engaging the rotatably driven cam, and with the other end connected to the rocker for moving it to the printing position. Variation of the impacting intensity may be accomplished by shifting the pivot point of the cam follower, as shown for example in German Pat. No. l,078,59l, and US. Pat. Nos. 2,926,768 and 2,879,876. Alternatively, the point of engagement between the cam follower and the rocker member may be varied as shown, for example, on Page 38 of the IBM Selectric Instruction manual, January 1966. However, in the latter example the adjusting mechanism, which is in the form of a pivotally supported lever having a pin engaging the cam follower, is carried on the rocker with the printing element, and such an arrangement adds an undesirable amount of mass which must be moved during each printing stroke. In either instance. the mechanism for varying the impact intensity of a type character against the recording medium is usually difficult to adjust, and composed of an undesirable number of parts.

Accordingly, an object of the present invention is to provide an impression control mechanism for regulating the impact intensity ofa type character against a recording element which is composed of a few parts which are easy to manufacture and require a minimum of space.

Another object of the invention is to provide an impression control mechanism in which the impact intensity of a type character striking a recording medium may be easily regulated.

A further object of the invention is to provide an impression control mechanism which minimizes the number of parts movable during a printing stroke so as to minimize the mass which must be moved and hence the inertia which must be overcome to impact a type character against a recording element.

Still other objects, features and advantages of the present invention will become apparent to those skilled in the art from a reading of the following detailed description of the preferred embodiment of the invention, taken in conjunction with the accompanying drawings, wherein:

FIG. I is a partial diagrammatic view of a printing arrangement having an impression control mechanism constructed in accordance with the present invention, and showing the relative position of the parts of the arrangement when the impression control mechanism is placed at one setting; and

FIG. 2 shows the printing arrangement of FIG. I with the impression control mechanism moved to another setting to show the change in the relative position of the parts.

Referring now in detail to the figures in the drawing, there is shown a typewriter printing arrangement, generally indicated 11, for printing type characters or other symbols on a recording medium, not shown, which may desirably be located on a platen 13. The type characters or other symbols to be printed, not shown, are formed on a generally spherical element 15 of a type carrier, generally indicated 17, and the type carrier 17 is supported for a movement from a normal or rest position to a printing position at the platen 13. As is conventional, printing is effected by impacting a selected type character against the recording medium and the type carrier 17 is driven in a printing movement to the printing position by a drive means, generally indicated 19, which may desirably be power operated by a motor, not shown. The printing arrangement is supported on a carriage 21 for movement along a line of type past the platen l3, and the carriage is mounted on a sleeve 23 which is slidably carried by a shaft 25 for movement past the platen 13. The recording medium, the type characters, the motor for operating the drive means 19 as well as the other portions of the typewriter are not shown since they form no part of the present invention and may be desirably conventional.

As shown, the type carrier 17 includes a rocker or base element 27 which is supported for pivotal movement by bolts 29 or other conventional means which may be suitably secured to the carriage 21. The drive means 19 is in the form of an eccentric cam 31 carried on a rotatably driven drive shaft 33 which undergoes a single revolution during each printing operation. As the cam 31 is rotatably driven through a single revolution. the type carrier 17 undergoes a printing movement from the normal position to the printing position to impact a type character against the recording medium to effect printing. After printing, the type carrier 17 is returned to the normal position by the urging of a resilient biasing means 35 as permitted by the rotational movement of the cam 31.

To control the intensity with which a type character impacts against the paper platen I3, and hence the impression on the recording medium, the printing arrangement II is provided with impact regulating means in the form of an impression control mechanism, gener ally indicated by reference numeral 37, for selectively controlling the force imparted to the type carrier 17 during a printing movement by the operation of the drive means 19. As shown. the impression control mechanism 37 includes a pivotally supported control member 39 having a projecting portion 41 for engaging the camming surface of the eccentric cam 31 and having another portion 43 for engaging the type carrier 17. The other portion 43 is in the form of a slot extending from adjacent the projection 41 toward the pivotal sup port of the control member 39, and the slot receives a pin 45 which is suitably secured to an extension 47 from the rocker base 27 of the type carrier 17. The projection 41 of the control member 39 is urged into engagement with the cam 31 by the resilient biasing means 35 which may be in the form of a spring stretched between the control member 39 and the carriage 21 and suitably secured thereto As the cam 31 rotates past the projection 41 during a printing operation, a driving movement is transmitted to the type carrier 17 through the projection 41 at the free end of the control member 39 whose upper portion 43 acts against pin 45 on the type carrier rocker element 27, driving the type carrier toward the platen 13.

lnasmuch as the cam 31 imparts the same movement to projection 41 each printing cycle, the impact velocity of the type carrier 15 is determined by establishing a rest position of the type carrier 15 and its base or support 27 closer to or away from the platen 13. The rest position is established by moving the drive pin 45 upwardly from FIG 1 to FIG 2 along portion 43 of the control member 39 and incident to its leftward movement. Thus, to selectively vary the impact velocity of the type carrier against the platen 13. The impression control mechanism 37 includes means in the form of an adjusting member 49 for moving the control member 39 with portion 43 acting against pin 45 to pivot rocker 27 about its pivot 29. As shown, the control member 39 is pivotally supported on the adjusting member 49 by suitable means, for example a pivot pin 51, and the adjusting member 49 is pivotally supported on the carriage 21 by suitable means, for example a pin 52. By pivotally moving the adjusting member 49 from one position to another position, as shown for example in FIGS, 1 and 2, the control member 39 is moved to the left, reducing the distance between control member pivot 51 and pin 45, and, its free end constrained by the cam 31, causing portion 43 to act on pin 45 and rock the type carrier rocker 27 counterclockwise about its pivot 29 to vary the distance between the platen 13 and the type carrier 17 while in the normal position. Since very little force is exerted on the adjusting member 49 during a printing operation, the adjusting member 49 may be held in a selected position by suitable detents.

In a printing operation. the type carrier 17 is driven from the normal position to the printing position to impact the selected type character against a recording medium on the platen 13 by rotatably driving the eccentric cam 31 through a single revolution. As the lobe of the cam 31 passes the projection 41 of the control member 39, the driving movement provided by the rotatably driven cam 31 imparts a printing movement to the type carrier 17. The type carrier 17 is driven against the urging of the spring 35, and after impact the spring 35 again urges the type carrier 17 to return to the normal position as permitted by the rotational movement of the cam 31. The intensity with which the type carrier impacts against the platen 13 is determined by the position of the adjusting member 49 which may be pivotally moved to a selected position to shift the control member 39 to the left or right, shortening or lengthening the distance between pivot 51 and pin 45, whereby its free end, constrained by cam 31, will cause portion 43, supporting pin 45, either to raise or lower pin 45 about rocker pivot 29 thus adjusting the rest position of the type carrier 15 relative to the platen 13. FIG. 2 shows the type carrier 15 initially positioned closer to the platen 13. As the angle of drive imparted by the cam 31 is constant, the type carrier 15 will be driven closer to the platen and strike with a greater velocity.

While only a single preferred embodiment of the invention has been illustrated and described, it will be apparent to those skilled in the art that various improvements and modifications may be made. Accordingly, it is to be understood that this invention is not to be limited by the illustrative embodiment, but only by the scope and spirit of the appended claims What is claimed is:

1. A single element printing machine comprising a frame,

a platen,

a type carrier having a plurality of type characters formed thereon,

means supporting said type carrier about a pivot axis on said frame whereby said type carrier can be driven from a rest position toward said platen to impact a selected character against said platen,

said support means having a pin thereon spaced from said pivot axis,

a drive cam rotatably mounted on said frame for driving said type carrier support means about its pivot axis,

a control member having one end located between said cam and said pin,

said one end supporting said pin and establishing a rest position of said type carrier support means,

and an operator controlled adjusting member for determining the impact velocity of said type carrier against said platen,

said control member being pivotally supported at its other end on said adjusting member at a point. said point and said pivot axis being on opposite sides of said pin,

said adjusting member being pivotally supported on said frame whereby pivotal movement thereof shifts said control member between said cam and said pin to rock said type carrier support means about its pivot axis to establish a rest position of said type carrier closer to or farther from said platen.

2. A printing machine as recited in claim 1, including spring means biasing said control member into contact with said cam.

3. A printing machine as recited in claim 2, wherein said one end of said control member is forked to receive said pin.

Claims (3)

1. A single element printing machine comprising a frame, a platen, a type carrier having a plurality of type characters formed thereon, means supporting said type carrier about a pivot axis on said frame whereby said type carrier can be driven from a rest position toward said platen to impact a selected character against said platen, said support means having a pin thereon spaced from said pivot axis, a drive cam rotatably mounted on said frame for driving said type carrier support means about its pivot axis, a control member having one end located between said cam and said pin, said one end supporting said pin and establishing a rest position of said type carrier support means, and an operator controlled adjusting member for determining the impact velocity of said type carrier against said platen, said control member being pivotally supported at its other end on said adjusting member at a point, said point and said pivot axis being on opposite sides of said pin, said adjusting member being pivotally supported on said frame whereby pivotal movement thereof shifts said control member between said cam and said pin to rock said type carrier support means about its pivot axis to establish a rest position of said type carrier closer to or farther from said platen.

2. A printing machine as recited in claim 1, including spring means biasing said control member into contact with said cam.

3. A printing machine as recited in claim 2, wherein said one end of said control member is forked to receive said pin.

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