US3807542A

US3807542A - Bounce suppressing mechanism

Info

Publication number: US3807542A
Application number: US00282090A
Authority: US
Inventors: W Jung
Original assignee: Teletype Corp
Current assignee: AT&T Teletype Corp
Priority date: 1972-08-21
Filing date: 1972-08-21
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30
Also published as: CA976104A; DE2342175A1; GB1432188A; JPS539134B2; JPS4957921A

Abstract

A spring having one end slidably engaging a pin extending from a retractable, motion inducing member, for example a print hammer in a printing apparatus, is rotatably mounted adjacent to a movable member, such as a type wheel. An intermediate portion of the spring is formed to contact and bear against the shaft of the type wheel so that when the print hammer is retracted, the spring is rotated about its mounting. This rotation results in the intermediate portion of the spring biasing the type wheel toward the print hammer. When the print hammer is brought into striking engagement with the type wheel, the pin on the print hammer moves thereby reducing the biasing action of the spring on the type wheel. Thus, the type wheel is free to move after being struck by the print hammer, but subsequent retraction of the print hammer applies a bias through the spring to suppress bouncing motion of the type wheel.

Description

United States Patent 1191 -lung [4 A r. 30, 1974 BOUNCE SUPPRESSING MECHANISM [75] Inventor: Werner Jung, Morton Grove, Ill. [57] ABSTRACT [73] Assignee: Teletype Corporation Skokie, A spring having one end slidably engaging a pin ex- [22] Filed; Aug 21, 7 tending from a retractable, motion inducing member, for example a print hammer in a printing apparatus, is PP 282,090 rotatably mounted adjacent to a movable member, such as a type wheel. An intermediate portion of the 52 US. Cl. 197/55, 101/93 c Spring is formed to Contact and bear against the Shaft [51] Int. Cl. G4lj 27/00 of the type Wheel so that when the Print hammer is 58] Field of Search 197/18, 52, 53, 55, 17; "acted, the Spring is rotated about its mounting This 101/93 176/36 rotation results in the intermediate portion of the spring biasing the type wheel toward the print ham- [56 References Cited mer. When the print hammer is brought into striking UNITED STATES PATENTS engagement with the type wheel, the pin on the print 7 1967 H I 101 93 C X hammer moves thereby reduclng the biasmg actlon of 322133 111965 $32531:::::::::::::::::::::.... 181,93 C Spring on the e wheel- The the h Wheel 18 3,504,623 4/1970 Sjallerm" 101/93 c we to move after l Struck by.the F 3,139,820 7/1964 Kittler 101/93 c but Subsequent rgtrachoh of the Pm1t hammer aPPes Primary ExaminerRobert E. Pulfrey Assistant ExaminerR. T. Rader Attorney, Agent, or Firm-J. L. Landis a bias through the spring to suppress bouncing motion of the type whe'el.

5 Claims, 4 Drawing Figures BOUNCE SUPPRESSING MECHANISM BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a bounce suppressing mechanism for a movable member, and particularly relates to a mechanism for minimizing the rebound of a type wheel in a printing apparatus after each printing operation.

2. Discussion of the Prior Art In various forms of printing apparatus, a movable type carrier is struck by a print hammer driving the type carrier toward a print receiving medium supported and backed by a platen. After the type carrier has contacted the platen, the type carrier rebounds from the platen and strikes either the print hammer or its backstop. If the type carrier is of sufficient mass, the type carrier will also rebound from the print hammer and will again contact the platen. This bouncing action of the type carrier causes smudging or blurring of the print receiving medium.

For example, US. Pat. No. 3,176,068 issued to N. A. Jacobs illustrates and describes a type wheel actuator mechanism including a cylindrical type wheel having type characters arranged on four levels. The type wheel is selectively positioned and then driven by the impact of a print bail or hammer toward the platen to perform a printing operation. A light coil spring bears against the shaft of the type wheel to insure restoration of the type wheel to a substantially vertical position after each printing operation.

It is desirable to increase the number and variety of type characters available on the type wheel. Increasing the number of type characters without reducing their size necessarily results in a larger, more massive type wheel. Then, however, the more massive type wheel is susceptible to bouncing action of increased magnitude after being struck by the print hammer. The light coil spring used with the less massive type wheel, such as the type wheel shown in the Jacobs patent, is not capable of suppressing the bouncing motion of the heavier type wheel. Thus, substantial smudging of the print receiving mechanism occurs when the larger type wheel is used.

Advantageously, the type wheel should be free to move toward the platen to effect a printing operation immediately after being struck by the print hammer, but the type wheel should not be free to rebound toward the platen at other times. Various forms of shock absorbing and cushioning devices for minimizing the rebound of moving members, such as type wheels, are known in the prior art. Generally, these devices merely apply a continuous anti-rebound force to the member, contrasted to permitting the member to move freely in the desired direction when struck by a motion inducing member and suppressing only the bouncing action.

Other devices for minimizing bounce may be coupled to a motion inducing member, such as a print hammer, and are totally ineffective for reducing the bounce or rebound of the moving member, such as a type wheel.

SUMMARY OF THE INVENTION It is, therefore, an objective of this invention to provide a new and improved bounce suppressing mechanism for a movable member.

Another object of this invention is to provide a new and improved mechanism for'minimizing the rebound of a type wheel in a printing apparatus.

A further object of this invention is to provide a new and improved mechanism for suppressing the bounce of a movable member whenever an associated'motion inducing member is in a nonmotion inducing position.

A bounce suppressing device in accordance with the principles of the invention may be included in a mechanism having a first member movable in-a forward direction and a retracting direction and a second member which is movable upon application of a striking force thereto. A preferred embodiment of the bounce suppressing device may couple the first and second members to permit the second member to move freely upon application of the striking force as long as the first member is moving in a forward direction. Upon movement of the first member in a retracting direction, however, the bounce suppressing device applies a biasing force to the movable second member to preclude undesirable bounce of the second member after application of the striking force.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will be apparent from the following detailed description when considered in conjunction with the accompanying drawing in which:

FIG. 1 is a partial end elevational view of a printing apparatus with parts broken away to illustrate a bounce suppressing mechanism in accordance with the principles of this invention; 7

FIG. 2 is a view, partly in plan and partly in section, taken along the line 2-2 of FIG. 1, of the bounce suppressing mechanism;

FIG. 3 is a fragmentary end view of the printing apparatus of FIG. 1 showing a print hammer in one position as it advances toward a type wheel; and

FIG. 4 is a view of the print hammer and the type wheel of FIG. 3 in the position of contact between the struck the type wheel.

DETAILED DESCRIPTION Referring to FIG 1 there is illustrated a printing apparatus, designated generally by the numeral 11, with parts broken away to show a bounce suppressing mechanism, designated generally by the numeral 12, in accordance with the principles of this invention.

The printing apparatus 11 is similar to the telegraphic page printer illustrated in the aforementioned Jacobs patent, the disclosure of which is incorporated herein by reference insofar as may be necessary to understand the structure and operation of the type of mechanism described and claimed herein.

The printing apparatus 11 includes a casting 13 which is movable transversely of a platen 14 and which carries a retractable print hammer 16 and a type wheel 17. A marking ribbon l8 and a print receiving medium 19, such as a web of paper,.are interposed between the type wheel 17 and the platen 14. The type wheel 17 may be selectively positioned relative to the platen 14 to orient a selected type character (not shown) carried on the type wheel. The print hammer 16 may then be operated to engage and move the type wheel 17 toward the platen 14 so that the selected type character presses the marking ribbon 18 into printing engagement with theprint receiving medium 19. Subsequent retraction of the print hammer 16 c ompletes one printing operation.

In the aforementionedpatent of N. A. Jacobs there is described in detail a mechanism 'for controlling the rotational and reciprocal motion of the type wheel 17. The type wheel 17 is cylindrical and has type characters on the outer surface which may be arranged-in a plurality of levels such as, for example, six levels. The type wheel 17 is mounted on a shaft 21 which is pivotally mounted at one end (not shown) to permit pivotal movement of the type wheel toward the platen 14 (FIG. 4). The shaft 21 is also fixed to a bearing ring (not shown) which is mounted for rotation and carries an annular gear 22 (FIG. 2).

A pair of racks 23 and 24 (FIG. 2) are slidably mounted on a spacer plate 26 and are supported and guided by a pair of shouldered buttons 27 and 28 (FIG. 2) which are mounted on a support plate 29. The pair of

racks

23 and 24 engage the annular gear 22 to selectively rotate the type wheel 17.

Another mechanism (not shown), but described in detail in the aforementioned patent of N. A. Jacobs, provides selective reciprocal motion to the shaft 21 and the type wheel 17, so that the combination of reciprocal and rotary motion can bring any type character on the type wheel into printing orientation.

Referring now to FIG. 2 there is illustrated, partly in plan and partly in section taken along the line 22 of FIG. 1, a view of the'printing apparatus 11. The print hammer 16 is oscillatably mounted on a shaft 32 which is in turn supported on a pair of

side plates

33 and 34 extending upwardly from the support plate 29. A coil spring 36, having a first end 37in engagement with a portion of the side plate 34, encircles the shaft 32. A second end 38 of the coil spring 36 is bent at a right angle so that the second end bears against one side of the print hammer 16 to urge the print hammer in a clockwise direction as viewed in FIG. 1.

Referring again to FIG. 1, the print hammer 16 is retracted, into the position shown, against'the force of the coil spring 36 (FIG. 2) by a print hammer actuating link 39, the upper end of which has a hook portion 41 that engages a hub 42 extending from the side of the print hammer.

A mechanism (not shown) is provided to move the print hammer actuating link 39 upwardly to release its control over the print hammer 16. The print hammer 16, however, will be held in the retracted position by a latch 44 having a latching portion 46 in engagement with a latching shoulder 47 formed in the print hammer. A print suppress latch 48 is also provided to engage the latching shoulder 47 when the printing apparatus 11 receives a signal which does not require a printing operation, for example, a space or a line feeding function.

The second end portion 38 (FIG. 2) of the coil spring 36 (FIG. 2) is limited in travel by the side plate 33 which is formed to engage the second end portion when the print hammer 16 is released by both the latching portion 46 and the print suppress latch 48. When the print hammer 16 is released, it is driven toward the type wheel 17 by the action of the coil spring 36 (FIG. 2). The second end portion 38 will strike the side plate 33 permitting the print hammer 16 to continue moving toward type wheel 17 on its own momentum.

Also mounted on the support plate 29 is a mechanism for lowering the marking ribbon 18 out of the printing position so that the type characters previously printed may be observed. A shaft 51 is rotatably mounted on the support plate 29 and has a trip and restoring lever 52 fixed to one end and a restoring lever 53 (FIG. 2) fixed to the other end. The trip and restoring lever 52 is coupled to a link 54 which controls the rotation of the shaft 51. Rotation of the shaft 51 raises or lowers the marking ribbon 18, which is held in a ribbon guide (not shown), into and out of printing position, respectively.

The printing. apparatus 11 and its operation, as described above, are illustrated and described in further detail in the aforementioned patent of N. A. Jacobs.

The bounce suppressing mechanism 12 includes a spring 56 having a first end 57 which slidably engages a pin 58 extending from the hub 42 of the print hammer 16 and a second end 59 (FIG. 2) disposed generally perpendicular to the first end and rotatably mounted in a first pivot or sleeve 61 (FIG. 2) which is secured to the support plate 29.

The first pivot 61 is mounted on the support plate 29 between the type wheel 17 and the platen 14 so that the shaft 21 of the type wheel is located between the print hammer 16 and the first pivot.

Referring again to FIG. 2, the spring 56 furtherhas an intermediate section 62 formed into a loop portion 63. The loop portion 63 is located between the first pivot 61 and a second pivot or sleeve 64, which is also mounted on the support plate 29. The first and second pivots 61 and 64 position the loop portion 63 so thatit bears against shaft 21 of the type wheel 17.

It will be apparent that the loop portion 63 may be of any convenient shape or may include an additional element extending fromthe intermediate portion 62 of the spring 56 to contact and bear against the shaft 21.

When the print hammer 16 is in the position shown in FIG. 1, the pin 58 holds the first end 57 of the spring 56 in the retracted position about the pivots 61 and 64 so that the type wheel 17 is retracted or biased away from the platen 14 by the force of the spring.

A mounting plate 67 is spaced above and secured to the support plate 29 intermediate the print hammer 16 and the annular gear 22, by a pair of screws 68 and 69. A pair of rocker members 71 and 72 are pivotably mounted between the mounting plate 67 and the support plate 29 by the pair of screws 68 and 69, respectively.

Each of the pairof rocker members 71 and 72 is formed with an upwardly extending projection 73 and 74, respectively, which support a coil spring 76 stretched between them.

The coil spring 76 stretched between the pair of'projections 73 and 74 exerts a biasing force on the rocker members 71 and 72 which pivots the rocker members about the screws 68 and 69, respectively. This pivotal motion of the rocker members 71 and 72 rotates them into contact with the

racks

23 and 24.

The force applied to the

racks

23 and 24 through the rocker members 71 and 72 urges the racks into firm engagement with the annular gear 22. This firm engagement substantially eliminates play or backlash between the annular gear 22 and the gear teeth carried on the racks 23 and '24. i

In operation, to initiate a printing operation, the print hammer 16 is released by a mechanism (not shown) from the retracted position shown in FIG. 1 by the latch 44 and the print suppress latch 48 and is rotated about the shaft 32 by the coil spring 36, driving the print hammer toward the type wheel 17. The second end portion 38 of the coil spring 36 then engages the side plate 33 thereby stopping the rotation of the coil spring but permitting the print hammer 16 to continue, on its own momentum, rotating about the shaft 32.

Referring now to FIG. 3 there is illustrated a fragmentary view of the printing apparatus 11 and the bounce suppressing mechanism 12 of FIG. 1, showing the print hammer 17 in one position as it advances toward the platen 14.

Comparing the relative positions of the shaft 32 and the pin 58 in FIG. 1 and in FIG. 3, it will be apparent that the pin is displaced in a clockwise direction around the shaft as the print hammer 16 rotates about the shaft and advances toward the type wheel 17. In the position shown in FIG. 1, the pin 58 holds the first end 57 of the spring 56 in the retracted position so that the loop portion 63 bears against the shaft 21 of the type wheel 17. The biasing force applied to the shaft 21 by the loop portion 63 in turn urges the first end 57 in an upward direction so that a biasing force is also applied to the pin 58 by the first end. Thus, clockwise displacement of the pin 58 permits the first end 57 of the spring 56 to slide along the pin moving the first end upwardly as shown in FlG. 3.

As the first end 57 moves upwardly, the retracting or biasing force exerted on the shaft 21 of the type wheel 17 by the loop portion 63 of the spring 56 is reduced, permitting the type wheel to move freely toward the platen 14 after being struck by the print hammer 16.

Referring now to F IG. 4 there is shown the type wheel 17 in the printing position contacting the platen 14 after being struck by the print hammer 16. After the biasing force exerted on the shaft 21 has been removed by the upward movement of the pin 58 as shown in FIG. 3, the print hammer l6 continues to rotate about the shaft 32 until the print hammer strikes the type wheel 17. The type wheel 17, having been previously positioned so that a selected type character carried thereon is in printing orientation, is driven toward the platen 14 by the impact of the print hammer 16. When the type wheel 17 contacts the platen 14, the marking ribbon 18 is forced into engagement with the print receiving medium 19, which is supported by the platen 14, to print the selected type character. The motion of the type wheel 17 between the time it is initially struck by the print hammer 16 and the time the type wheel first strikes the platen 14 occurs with minimum restraint from the bounce suppressing mechanism 12.

The print operation is completed by retracting the print hammer from the position shown in FIG. 4 toward the position shown in FIG. 1, with the hook portion 41 of the actuating link 39 engaging the hub 42 which extends from the print hammer.

Retraction of the print hammer 16 moves the pin 58 in a counterclockwise direction about the shaft 32, or downwardly as viewed in FIG. 4. This counterclockwise movement of the pin 58 also moves the first end 57 of the spring 56 downward, applying an increasing force to the shaft 21 through the loop portion 63 to bias the type wheel'l7 away from the platen 14. As the pin 58 continues to move toward the positionof FIG. l, the

bias force applied to the shaft 21 rapidly increases.

After the type wheel 17 has initially struck the platen 14, the type wheel rebounds from the platen toward the print hammer 16 as it is being retracted. Although the type wheel 17 is free to rebound from the platen 14, any further rebound or bounce such as rebound from contact with the print hammer 16 as it is retracted, will be restrained by the bounce suppressing biasing force of the spring 56.

Thus bounce of the type wheel 17 is minimized by the bounce suppressing mechanism 12 whenever the print hammer 16 is in a retracted position, or is being retracted. The type wheel 17 is permitted to move freely toward the platen 14 only when initially struck by the print hammer 16 during each printing operation and is not free to rebound toward the platen at other times. In this way, the type wheel 17 strikes the platen 14 only once during each printing operation, thereby preventing smudging or blurring of the type characters printed on the print receiving medium 19.

It is to be understood that the above-described embodiment is simply illustrative of the invention, other embodiments may be devised by those skilled in the art which will employ the principles of the invention and face, a mechanism for suppressing the bounce of the v movable member after striking the surface, which comprises:

a pivot mounted adjacent to the movable member;

a pin extending from the retractable hammer; and

means responsive to retraction of the hammer, for

releasably applying a biasing force to the movable member to bias the movable member away from the surface and toward the retractable hammer, said means having a first end portion for engaging said pin and a second end portion mounted in said pivot for movement relative thereto so that upon retraction of the hammer said pin engages said first end portion to releasably apply said biasing force to a third portion intermediate said first and second end portions, said third portion being formed to contact and bear against the movable member so that said biasing force is applied thereby whenever the hammer is retracted and so that upon initial movement of the hammer toward the movable member said pin relieves said biasing force thereby permitting the movable member to strike the surface.

2. In a printing apparatus having a retractable hammer, a movable type wheel, and a printing medium, a mechanism for suppressing the bounce of the type wheel after each printing operation, which comprises:

a pin extending from a side portion of the retractable hammer; and

a spring having a first end slidably engageable with said pin, a second end rotatably secured between the type wheel and the printing medium, and an intermediate portion formed to contact a portion of the type wheel so that said pin slidably engages and biases said first end upon retraction of the hammer to rotate said second end and thereby move said a distinct means, separate from the retractable hammer and the movable member, coupling the retractable hammer and the movable member and responsive to the retraction of the hammer, and applying a biasing force to bias the movable member toward the retractable hammer;

I and means responsive to the initiation of movement of the retractable hammer into striking engagement' with the movable member for relieving said biasing force so that the movable member is freely movable when struck by the retractable hammer the distinct means having a first portion cooperating with the relieving means and a second portion mounted for piovtal movement.

4. A mechanism as set forth in claim 3 wherein said distinct means comprises a spring having the first portion held in biasing engagement with the relieving means and a third portion bearing upon the movable member to exert a bounce suppressing biasing force thereon when the hammer is moved in the retracting direction. I

5. A mechanism as set forth in claim 4 wherein said relieving means comprises a pin extending from the hammer and slidably engaging said first portion of said spring so that, upon movement of the hammer into striking engagement with the movable member, said pin slides along said first portion to relieve the biased engagement of the first portion with the hammer thereby releasing the bounce suppressing biasing force from application to the movable member.

Claims

1. In a device having a retractable hammer for driving a movable member into striking contact with a surface, a mechanism for suppressing the bounce of the movable member after striking the surface, which comprises: a pivot mounted adjacent to the movable member; a pin extending from the retractable hammer; and means responsive to retraction of the hammer, for releasably applying a biasing force to the movable member to bias the movable member away from the surface and toward the retractable hammer, said means having a first end portion for engaging said pin and a second end portion mounted in said pivot for movement relative thereto so that upon retracTion of the hammer said pin engages said first end portion to releasably apply said biasing force to a third portion intermediate said first and second end portions, said third portion being formed to contact and bear against the movable member so that said biasing force is applied thereby whenever the hammer is retracted and so that upon initial movement of the hammer toward the movable member said pin relieves said biasing force thereby permitting the movable member to strike the surface.

2. In a printing apparatus having a retractable hammer, a movable type wheel, and a printing medium, a mechanism for suppressing the bounce of the type wheel after each printing operation, which comprises: a pin extending from a side portion of the retractable hammer; and a spring having a first end slidably engageable with said pin, a second end rotatably secured between the type wheel and the printing medium, and an intermediate portion formed to contact a portion of the type wheel so that said pin slidably engages and biases said first end upon retraction of the hammer to rotate said second end and thereby move said intermediate portion to urge the type wheel toward the retractable hammer.

3. In a device having a retractable hammer for striking a movable member, a mechanism for suppressing the bounce of the movable member which comprises: a distinct means, separate from the retractable hammer and the movable member, coupling the retractable hammer and the movable member and responsive to the retraction of the hammer, and applying a biasing force to bias the movable member toward the retractable hammer; and means responsive to the initiation of movement of the retractable hammer into striking engagement with the movable member for relieving said biasing force so that the movable member is freely movable when struck by the retractable hammer the distinct means having a first portion cooperating with the relieving means and a second portion mounted for piovtal movement.

4. A mechanism as set forth in claim 3 wherein said distinct means comprises a spring having the first portion held in biasing engagement with the relieving means and a third portion bearing upon the movable member to exert a bounce suppressing biasing force thereon when the hammer is moved in the retracting direction.