US3553405A

US3553405A - Foot switch for dictating machine

Info

Publication number: US3553405A
Application number: US757268A
Authority: US
Inventors: Kurt Konrad Guettinger
Original assignee: Dictaphone International AG
Current assignee: Dictaphone International AG
Priority date: 1967-09-05
Filing date: 1968-09-04
Publication date: 1971-01-05
Anticipated expiration: 1988-01-05
Also published as: GB1219132A; CH468709A

Abstract

A foot-operated control switch having a contact actuating foot pedal which is moved into successive switch positions against a spring force which increases from the first switch position to the next switch position. Because the forces necessary to move the pedal are different for the successive switch positions, the switch positions are precisely defined.

Description

United States Patent Kurt Konrad Guettinger Pfall'hausen, Switzerland 757,268 Sept. 4, 1968 Jan. 5, l 971 Dictaphone International AG Wettingen, Aargau, Switzerland [32] Priority Sept. 5, 1967 [33] Switzerland 31 No. 12,363/67 [72] Inventor [21 1 Appl. No. [22] Filed [45] Patented [73 Assignee [54] FOOT SWITCH FOR DICTATING MACHINE 12 Claims, 5 Drawing Figs.

[52] US. [51 1 Int. [50] Field of Search 200/865 I'l0lh 3/14 ZOO/86.5

[56] References Cited UNITED STATES PATENTS 2,828,379 3/1958 Simonds et al ZOO/86.5 2,95 7,960 10/ l 960 Ginn 200/ 86.5 3,250,874 5/1966 lvins ZOO/86.5 3,432,791 3/1969 Palmer 200/86.5(X)

Primary Examiner-H. 0. Jones Attorney-Curtis, Morris & Safford ABSTRACT: A foot-operated control switch having a contact actuating foot pedal which is moved into successive switch positions against a spring force which increases from the first switch position to the next switch position. Because the forces necessary to move the pedal are different for the successive switch positions, the switch positions are precisely defined.

PATENTEDJAH 5m I 8553405 "SHEETIUFZ INVI'LNI'I'UH. KURT GUETTINGER IIY ATTORNEYS PATENTEDJAN SIS}?! SHEET 2 OF 2 INVI'JN'IOR. KURT GUETTINGER IIY ATTORNEYS FOOT SWITCH FOR DICTATING MACHINE The present invention relates to a foot-operated control switch for dictating machines and the like and more particuit is depressed, and even more particularly this invention relates to a control switch with a pedal control wherein the pedal is arranged to-oppose a spring force which increases between successive switch positions.

The object of this invention is to provide a simplified, easily 1 operable, dependable dictating machine control switch having a foot pedal which can assume successive, yet precisely defined, switch positions.

In accordance with the teachings, and to accomplish the objectives of this invention, a control is provided having a foot pedal, a cam, and a follower member. The follower member of the control is biased against the cam, and both the cam and the follower member are arranged for relative movement with respect to each other. The foot pedal of the control is movably connected to eitherthe cam or to the follower member.

When the foot pedal is not depressed,- that is, when it is in its 1 rest position, the follower member assumes a detent, or catch,

position on the cam. As the foot pedal is depressed, the cam and follower are caused to leave the detent, or catch, position and to'move with respect to each other. Adjacent the detent, or catch, position section of the cam is a cam section with practically no slope which corresponds generally to a first switch positionof the control. Adjoining this slopeless section, is another section with a rising slope which corresponds generally to a second switch position. Additional cam sections may also be included. These various cam sections make it I necessary that different pressures be applied to the foot pedal to achieve the various switch positions of the control.

Furthermore, in accordance with the teachings of this invention, a return spring, whose initial tension can be adjusted, is provided to apply a substantially constant return-to-rest force upon the elements of the control throughout the entire switching range.

The invention, as illustrated schematically and in a preferred embodiment will be described in detail below with reference to the accompanying drawing in which:

FIG. 1 shows schematically the essential parts of a footoperated control switch constructed in accordance with this invention;

FIG. 2 is a force curve for the switch illustrated in FIG. 1;

FIG. 3 shows schematically, in cross section, a preferred embodiment of a foot switch constructed in accordance with this invention and also shows arrows representing the forces occurring upon actuation of the switch;

FIG. 4 shows in top plan view a preferred embodiment of a foot switch constructed in accordance with this invention with its foot rest removed to better illustrate the parts located beneath the foot rest;

FIG. 5 shows in vertical cross section the foot switch of FIG. 4 with its foot rest in position.

In the foot-operated control switch shown schematically in FIG. 1 a cam, or profile body, 1 is mechanically connected by a lever 2 with a foot pedal, or foot rest, 3 of the foot switch so that upon depression of the foot rest the profile body will be raised. In the example shown the foot rest is a plate which is rotatably supported at one end about a horizontal shaft 4. The other end of the foot-rest plate presses against one end of the lever 2, shown as force arm 5. The other end of the lever 2, load arm 6, is supported in a groove 7 in the base of the profile body I. The profile body 1 is supported and guided in any suitable manner so that it can move vertically. The load arm 6, under the action of a return spring 8, holds the profile body 1 against the bottom plate 9 of the foot switch when no pressure is exerted against the foot rest 3.

One side surface of the profile body 1 is formed as a cam surface, or slide surface, 10 fora follower member. This follower member, in the embodiment shown, is a leaf spring 11 bent in the shape of a C. The lower arm of the spring 11 is fastened to the bottom plate 9. The upper arm of the spring II has an end 12 bent in the shape of a circular arc. This curved spring end 12 serves as a follower member. Upon the upward or downward movement of the profile body, the spring end 12 slides on the cam surface, or slide surface, 10. The shape of the cam causes tensioning of the leaf spring 11 to a greater or lesser extent. The other side surface of the profile body I, opposite the slide surface 10, has projections I3. Near the projections 13 two pairs of contacts 14 and 15 are located one above the other. These contact pairs are actuated in succession upon an upward stroke of the profile body.

The cam surface 10, consists of three surface sections. namely an upper section 16, a central section 17, and a lower section 18. The upper section '16 is formed by a horizontally extending incision in the cam, or profile body, I, which provides a detent, or retaining catch, for the curved spring end 12 when the profile body 1 and/or the foot rest 3 is in the rest position. The central section 17 consists of a vertical flat surface, and the lower section 18 consists of an inclined fiat surface.

The transition from the central surface section 17 to the lower surface section 18 represents a stop for the end 12 of the spring 11 when the profile body 1 is moved upward. The two contact pairs 14 and 15, and projections 13 are so arranged, and/or are of such shape, that when the profile body is in the rest position, i.e. when the spring end 12 is engaged in the detent or catch position, both contact pairs 14 and 15 are open. This position is marked I in FIG. 1. Position II is present when the profile body, or cam, 1 is raised to such an extent that the spring end 12 is at the transition between the central surface section 17 and the lower surface section 18. The spring end 12 strikes against the stop-presented by the transition between the two surfaces. In Position II the first contact pair 14 will be actuated, i.e. closed, and the second contact pair 15 will be opened. In Position III the second contact pair 15 is also closed and the Spring end 12 is on the lower cam surface section 18'at a certain distance from the stop point between sections 17 and 18. This Position III can be fixed by a stop (not shown in FIG. 1) which limits the stroke of the profile body.

The force of the return spring 8 and of the leaf spring 11 (or follower member, 12, due to the leaf spring 11) must be overcome, upon actuation of the foot switch, by pressure on the foot rest 3. FIG. 2 shows a curve of the force required for the foot switch. Only the essential variations in pressure or force with respect to the displacement of the foot rest or profile body are shown.

The return spring 8 is of such spring characteristics and is arranged in such a way, as will be described in detail below, that the return force present by spring 8 remains practically constant throughout the entire switch range of the foot switch, i.e. for the lifting of the profile body 1 out of Position I through Position II and into Position III. In order to overcome the return force of the return spring 8, a force F2 is required which is shown in the Force-Path diagram of FIG. 2 by a line parallel to the abscissa. The tension F1 of the spring 11 is dependent on the path of the cam 10.

In the rest position the spring 11 is engaged with a certain pressure in the detent position 16 of the profile body I. To disengage the spring 11 a corresponding force is required which is transmitted from the upward pressed profile body to the curved spring end 12. Accordingly, the lifting of the profile body begins only when the pressure on the force arm 5 of the lever 2 has become great enough to disengage spring end 12. Accordingly, the required-force curve has, for Position l, a vertically extending branch which is composed of the section a, the force necessary to overcome the return force of the spring 8, and the section b, the force required to disengage the spring 11 from the detent position.

Upon the lifting of the profile body I out of Position I into Position II, the spring end 12 slides on the vertical cam section 17. In order to lift the profile body this distance it is necessary, in addition to supplying the force F2, to supply a force necessary to overcome the friction between spring end [2 and lowing branch b.

The end of the branch corresponds to the Position ll ofthe profile body in the diagram, i.e. the position in which thespring end 12 comes against the stop formed by the cam surface section 18 at its junction point with cam surface section: 17. In order to overcome this stop it is necessary to apply a. certain additional force, indicated in the diagram as vertical branch d. The slope of the cam surface 18 of the profile body 1 is selected so that the force required to overcome this stop is greater than the force for disengaging the spring end 12 from the detent position. This is readily possible since the spring has a greater tension in Position II than in position I.

Upon further rise of the profile body 1 out of position 11 into Position III the spring end 12 slides on the cam section 18, whereby the spring 11 is subject to further tension. Corresponding to this movement of the profile body 1, a rising straight line results in the Force-Path diagram as a branch of V the force curve. The end of this branch of the curve designates,

Position III of the profile body. I

The force F3 which is necessary toactuate the switch and i which acts on the force arm 5 of the lever 2 is provided, in the case of a foot resting on the foot rest 3, by the weight'of the foot and by an additional applied pressure. The portion of the force supplied by the weight of the foot is indicated in the diagram of FIG. 2 by a line F3, parallel to the abscissa. The initial tension of the return spring 8 is adjusted in such a manner that this parallel line F3 in the diagram intersects the branch c of the curve, preferably at the center C between its end points A and B; The pressure F3 which must be applied in addition to the weight of the foot in order to actuate the foot switch is represented by all sections of the curve which lie above this DA does the profile body 1 rise and drop" out of the rest. position (Position I) into the first switch position (Position II) 1 in which position the pair of contacts 14 is closed. The force required in Position II is indicated by the Point B on the curve. Point B lies below the parallel line F3,. Accordingly, in order to hold the switch in the first switch position, (i.e. in Position- II), the weight of the foot is sufficient by itself. For the actuating of the second pair of contacts 15 the profile body must be lifted from Position ll into Position Ill. To effect this, the pressure required on the foot rest is greater than that required to lift the profile body into Position II. Thus, this position ll, i.e.

the'switch position most frequently used in operation, is stable and can not, for all practical purposes, be passed by unnoticed.

The combination described above of a path-dependent:

operating force, corresponding to the diagram of FIG. 2, and a constant return force which can be adapted to the weight of the foot, assures for the easy, energy-saving, dependable actuation of the foot switch.

A preferred embodiment of such a foot switch is shown in FIGS. 3, 4, and 5. FIG. 3 schematically shows the construction. of this switch. As can be seen, the switch has two similar sec tions which are symmetrical about a vertical center line. Each section is formed essentially in the same way as the switch shown in FIG. 1. The profile body 19, accordingly, is provided with slide surfaces 20. and 21 on each of two opposite sides.

' Each slide surface is shaped in exactly the same manner as the Furthermore, the profile body l9-isprovided'withgrooveszfl. and 26 cut respectively on two opposite sides-of the profile body 19. The ends of'the load arms 27"and 28 of the two levers 29 and 30areengaged in the grooves 25 and 26. For ease of-il lustration, the grooves 25' and 26 have been shown atthe top of the profile body, while in the-actual embodiment they are located in the base of the profile body FIG. L' Thelevers 29 and30'aredouble-arm levers. hosepiyotpoints 31 and 32 are supported on the base plate of 00 witch. The foot rest'33 is in theform of a hollow sphe a gment and rests on the force arms 34 and'35of the two ley The return spring is a leaf spring 36 which-is supported on the load arms 27 and 28-of the levers; Each supportpoint-ST and 38 ,lies in Q the vicinity of, apivot point'31 and 32' which is preferably spaced from the latter by-a distance which corresponds to the length of the force arm. In the center of the leaf spring is a tensioning device by which the initial tension F of the springcan be, adjusted. lnthis embodiment, a small spring path is obtained overtheentire stroke of the profile body so that, even. with the relatively large length of'spring', th'e return force is' substantially constant throughout the entireswitch range.- The 4'and 5; In the plan view of FIG. 4-the"foo"t 'rest has been omitted in order to more readily show the parts'locatedb'elow the foot rest. The individual parts are mounted o'n'a circular plate -41.which is provided with a rubber covering 42 on its underside. so that'the switch will be prevented from sliding on polished floors. Both levers 29 and 3.0are T-shaped with rela tively wide crossarms and are formed of sufficiently thick plate material. They are arranged on the base plate 41 so thattheir feet'come together in the center of the plate and rest in grooves located in the profile body 19. Each lever is turnable,

orrotatable, about the center line of the crossarm by which it'- is supported. For example, levers 29 and 30 are rotatable. at the ends of the arm about pivot points 43 and 44 respectively. The longitudinal edges of the cross arm are bent obliquelyupward- The profile-body 19 is arranged to slide on a vertical' center pin 45 and the curved ends23'and 24 of the U shape leaf spring 22 "rest with a certain pressure'on the slide surfaces 20 and 2110f the profile body (see FIG. 3). The return spring 36'rests at its two ends on the upward bent inner edges 46 and :47 of the lever crossarms. The center of the return spring is action on the ring 49.- To support the foot rest 33 a leaf springr 50 can suitably be'employed as shown. This leaf spring is held: on'both ends by two stay bolts 51 fastened to the baseplate 41. The center of this leaf spring is screwed from the outside to the center point of the foot rest.

Switch contacts 39 and 40 are actuated byoperation of either of the

levers

29 and 30. The operation of the foot switch shown in FIGS; 4 and 5 corresponds entirely to the operationof the foot switch described in connection with FIG. 3. By turning the head 55 of the set screw 4 8,-which.is counter sunkin-the bottom of the foot switch, the initial tension of thereturn spring 36 is adapted, as previously described, to the weight of thefoot. In setting the screw 48 only the portion of the weight of the foot resting on the foot rest, rather than the entire weight of the foot, need be taken into consideration. By trial and error the correct adjustment can rapidly be determined. a

When operating the foot switch it is immaterial at what point the foot rest against the foot rest or at what point the foot depresses the rest. For all points of foot contact on the 'rest the switching properties described are retained. A light pressure exerted for a short time brings the switch into its first switch position and a stronger pressure brings the switch into its second switch position. In the second switch position the dictating machine is caused to backspace.

It should be understood, of course, that the foregoing disclosure relates only to a preferred embodiment of the invention and that numerous modifications or alterations may be made therein without departing from the spirit and the scope of the invention as set forth in the appended claims.

Iclairn:

l. A foot-operated control switch having a foot pedal normally in a rest position and movable from said rest position to at least two respective switch positions wherein normally open switch contacts are caused to be closed, said foot pedal movably connected to one element of a movably mounted cam and follower and adapted to cause relative movement between said cam and said follower and to move said cam and said follower into defined positions relative to each other corresponding to said rest position and said switch positions of said foot pedaLsaid cam has a prearranged pattern including a notch and the follower assumes a detent position in said notch on the cam when the foot pedal is in the rest position and wherein adjoining the detent position on the cam is a cam sec- I tion which extends substantially without slope which is immediately followed by another cam section having a raised slope and wherein saidfoot pedal is maintainable in said two switch positions, said follower biased against said cam and held there by a force which varies in accordance with the prearranged pattern as said cam and said follower move with respect to each other, said force providing a changing resistance to the relative motion of said cam and said follower and hence providing a changing resistance to the motion of said foot pedal, said changing resistance used to indicate said switch position, whereby the switch positions of said footoperated control switch are clearly defined.

2. A foot-operated control switch as described in claim 1 .having an associated adjustable return spring adapted to supply a substantially constant return force for all positions of said foot pedal.

3. A foot-operated control switch as described in claim 2 wherein said foot pedal is connected to said cam, said force biased follower is stationary, and said cam is movable with respect to said follower.

4. A foot-operated control switch as described in claim 3 having a spring and wherein said force is supplied by said spring.

. 5. A foot-operated control switch as described in claim 4 wherein one end of said spring is said follower.

6. A foot-operated control switch as described in claim 5 having a lever mechanism connecting said foot pedal to said cam wherein said lever mechanism is also connected to said return spring and wherein said return spring is attached so that larger transmission ratio is present between the foot pedal and the cam than between the cam and. the return spring.

7. A foot-operated control switch as described in claim 6 wherein the lever mechanism consists of two double arm levers which are arranged opposite each other and wherein load arm ends of each of said levers is movably connected to the cam.

8. A foot-operated control switch as described in claim 7 wherein said levers have at least 3 points of attack lying on a circular arc adaptable to receive an actuating force and wherein said axes of rotation of said lever arms are symmetrically spaced with regard to said are.

9. A foot-operated control switch as described in claim 8 wherein said foot pedal is shell shaped and wherein said foot pedal may be depressed at any point along its periphery to actuate at least one of said levers. I

10. A foot-operated control switch as described in clarm 9 wherein the return spring is a leaf spring supported on the load ends of the levers, the initial tension of said leaf spring being adjustable.

11. A foot-operated control switch comprising, a foot pedal and a return spring therefor, a switch actuator having a control surface and operatively connected to said foot pedal for movement against the bias of said return spring from an initial position to a first switch position, means spring biased against said control surface and cooperating therewith providing a resistive force to movement of said foot pedal whereby the force resulting from the weight of the foot is less than the force required for initially moving said switch actuator from its initial position but greater than the force required to hold the switch in said first switch position once said second switch position is obtained.

12. A foot-operated switch control as described in claim ll wherein said switch actuator may be moved to a second switch position by increasing the force required to hold said switch in said first position.

Claims

1. A foot-operated control switch having a foot pedal normally in a rest position and movable from said rest position to at least two respective switch positions wherein normally open switch contacts are caused to be closed, said foot pedal movably connected to one element of a movably mounted cam and follower and adapted to cause relative movement between said cam and said follower and to move said cam and said follower into defined positions relative to each other corresponding to said rest position and said switch positions of said foot pedal, said cam has a prearranged pattern including a notch and the follower assumes a detent position in said notch on the cam when the foot pedal is in the rest poSition and wherein adjoining the detent position on the cam is a cam section which extends substantially without slope which is immediately followed by another cam section having a raised slope and wherein said foot pedal is maintainable in said two switch positions, said follower biased against said cam and held there by a force which varies in accordance with the prearranged pattern as said cam and said follower move with respect to each other, said force providing a changing resistance to the relative motion of said cam and said follower and hence providing a changing resistance to the motion of said foot pedal, said changing resistance used to indicate said switch position, whereby the switch positions of said footoperated control switch are clearly defined.

2. A foot-operated control switch as described in claim 1 having an associated adjustable return spring adapted to supply a substantially constant return force for all positions of said foot pedal.

5. A foot-operated control switch as described in claim 4 wherein one end of said spring is said follower.

6. A foot-operated control switch as described in claim 5 having a lever mechanism connecting said foot pedal to said cam wherein said lever mechanism is also connected to said return spring and wherein said return spring is attached so that larger transmission ratio is present between the foot pedal and the cam than between the cam and the return spring.

8. A foot-operated control switch as described in claim 7 wherein said levers have at least 3 points of attack lying on a circular arc adaptable to receive an actuating force and wherein said axes of rotation of said lever arms are symmetrically spaced with regard to said arc.

9. A foot-operated control switch as described in claim 8 wherein said foot pedal is shell shaped and wherein said foot pedal may be depressed at any point along its periphery to actuate at least one of said levers.

10. A foot-operated control switch as described in claim 9 wherein the return spring is a leaf spring supported on the load ends of the levers, the initial tension of said leaf spring being adjustable.

12. A foot-operated switch control as described in claim 11 wherein said switch actuator may be moved to a second switch position by increasing the force required to hold said switch in said first position.