US3428765A - Sign sensing switch for numerical control system - Google Patents

Description

Feb. 18 1969 A- R. LUDWIG SIGN SENSING SWITCH FOR NUMERICAL CONTROL SYSTEM Filed June 7, 1966 Sheet T a m W M 1 e m 7 m p, M W A M w M M i H 4 a w a m 7 3 2 53 2 4 c Z i 2 M 4 Z 2 w 2 2 L\7 7 K MK ,w SW fl fif J 3 7 4 4 J Z a m 2 g 4 a A. R. LUDWIG Feb. 18, 1969 Sheet Filed June 7. 1966 LT k a Q K e w w 2 E W /u. 7/ im 6 B 4 WW xm 2 k: 2 7 5 A m a 5 T Ll P L Q\ M 6 1||||| T m w a Z I a I Z1 a f. r u n 3 u l 8 u I n 5/ F :II IL r 1L 1 v w a m 5 M z z 6 INVENTOR.

14165? (MOM/G United States Patent 0.]

3,428,765 SIGN SENSING SWITCH FOR NUMERICAL CONTROL SYSTEM Albert R. Ludwig, Timberlake, Ohio, assignor to Zagar, Inc., Cleveland, Ohio, a corporation of Ohio Filed June 7, 1966, Ser. No. 555,782

US. Cl. 200-6139 Claims Int. Cl. H01h 3/10 ABSTRACT OF THE DISCLOSURE An electrical switch which is responsive to the direction in which the switch is turned, comprising a housing, a shaft rotatable in the housing, a cam carried by the shaft and having a cam follower engaged by the cam for operating first and second switches through firstand second switch actuating means. If the shaft is rotated in a first direction, the first switch is operated and, similarly, if the shaft is rotated in a second direction, the second switch is operated.

This invention relates generally to electrical switching circuits and more particularly to sign or directional sensing switches particularly adapted for use in input registers of numerical control systems.

There are many applications, particularly in the case of rotary switches of the multiple position type, where it is desired to provide a sensing means or signal to indicate the direction in which the switch is turned. For example, certain numerical control systems such as that disclosed in my co-pending application, Scr. No. 532,029, filed Jan. 17, 1966, now US. Patent No. 3,346,183, issued Oct. 10, 1967, have a position input in the form of an input register in which the count is determined by the setting of a plurality of rotary switches. To avoid an unnecessary series of operations it is desirable to have a sign or direction input signal to indicate whether the new setting .in a register is higher or lower in numerical value than the existing setting. While this can be done by a separate input, chances of error are reduced and speed of opera- .tion increased by the present invention which provides for an automatic signal of sign or direction when the new position is set in the input register.

The foregoing is accomplished by the provision of a novel switching arrangement which is combined with each of the rotary switches so as to close different sets of con tacts depending upon the direction of rotation of the switch shaft. Thus, if the shaft is turned counter-clockwise one circuit is closed upon each step of switch rotation and if the switch is turned clockwise, a different switching circuit is closed. These circuits may be arranged to actuate relays to produce a sign or direction sensing signal and may be arranged with each of the switches so that if the switches are set in numerical order starting with the highest digit to be changed, a correct sign input will be produced concurrently with the new position input.

The switching unit for providing this feature includes astar wheel member which is rotatable with the switch shaft and is mounted within a housing having a ball in engagement with the star wheel. The sides of the notches in the star wheel may be at approximately 90' degree angles and at similar angles may be a pair of springloaded plungers which may rest in contact with the ball. In any case, the arrangement is such that rotation of the star wheel in one direction or the other establishes a driving relationship between the ball, as the driving member, and one of the plungers so as to actuate a switch by movement of that plunger. Thus, each step-wise rotation of the switch shaft produces a momentary closing of the switch contacts to indicate the direction of rotation of the switch shaft. The switch may be utilized in a circuit m 3,428,765 Patented Feb. 18, 1969 which is responsive only to the first impulse, that is the first closing of one or the other contacts by rotation of one of the switches, so that the sign sensing circuit is thereafter deactivated and subsequent numerical changes do not affect the system.

The switch in its construction has a simplicity which lends itself to low cost of manufacture while maintaining a high degree of reliability and is particularly arranged so as to be adaptable for addition to existing rotary switches with a minimum of alteration. Further objects and advantages of this invention will readily become apparent to those skilled in the art upon a more complete understanding of the invention as disclosed in the drawings and the following detailed description.

In the drawings:

FIG. 1 is a side-elevational view of a rotary switch incorporating the switching mechanism according to the preferred embodiment of the present invention;

FIG. 2 is a rear-elevational view of the switch shown in FIG. 1;

FIG. 3 is an enlarged cross-sectional view through the direction sensing switch taken on line 33 of FIG. 1; and

FIG. 4 is a schematic view of an input register circuit incorporating the switch of FIGS. 1-3.

Referring now to the drawings in greater detail, the switch unit shown in FIGS. 13 includes an ordinary rotary selector switch which may be of the ten or twelve position wafer type, and to which the direction sensing switch has been added. This rotary switch may be of any usual type well known in the art and commercially available and includes a housing 10 having a projecting threaded boss 11 by which the switch is attached to a control panel. A rotary shaft 12 extends axially through the housing 10 in which it is journalled by suitable bearing means. A selector switch unit 14 provides the multiple position switches within a housing and to which electrical connection may be made by means of the radially extending lugs 15. A pair of studs 16 extend between the housing 10 and the switch unit 14 and secure the assembly together by means of nuts 17. Since the structure of this switch is well known in the art and forms no part of the present invention except to the extent described hereinafter, it will not be described in further detail.

The housing 20 carries the direction sensing switch mechanism and is mounted on the studs 16 between the housing 10 and selector switch unit 14. This mounting is merely an arrangement for convenience to allow access to the lugs 15 for soldering purposes, and it is understood that the housing 20 of the direction sensing switch mechanism can be suitably actuated by any extension of the shaft 12 on either end of the switch. The housing 20 is preferably made of an insulating material and may be of uniform thickness as shown most clearly in FIG. 1. If desired for insulating purposes, insulating plates or covers may be placed on the front and back sides of the housing 20 to insulate it from the housing 10* or selector switch units 14.

The housing 20 has a circular opening 22 extending therethrough about the axis of shaft 12. A rotary cam member or star Wheel 24 is mounted within the opening 22 and secured to the shaft 12 by suitable means such as a press fit or a key to rotate therewith. The star wheel 24 has a plurality of cam surfaces in the form of notches 26 around its outer periphery. Preferably, these notches 26 have sides forming an included angle of about degrees and are equal in number and spacing to the rotary positions of the switch. In the case of a ten position switch there may be ten of the notches 26, or as shown as applied to a twelve position switch with two positions unused, there are twelve notches. The notches must have an angular spacing corresponding to the angular switch positions to insure that the normal detent mechanism of the switch for holding the shaft in a given position also allows appropriate alignment of the notches 26.

The housing has a pair of left and right bores 28 and 29 extending radially therein with their axes substantially normal to the notch sides when the notch is centered at the intersection of the axes of the bores 28 and 29. It will be noted that these bores are located so that at their inner ends the sides are substantially in line with the adjacent notch side. The bores have a diameter at least as great as that of the ball 35 which is located within the notch 26 so that rotation of the star wheel will cause the notch sides to engage the ball and force it into the appropriate one of the bores. Plungers 30 and 31 are mounted within the bores 28 and 29 for a free-sliding fit and may be provided with steps indicated in 32 and 33 to limit inward movement of plungers toward the ball 35. It will be seen with this arrangement that when the notch is centered, both of the plungers rest at the inner ends of their bores with the steps 32 and 33 in abutment against the housing and substantially in contact with the ball 35 when it is also in contact with the sides of the notch 26. Any rotation of the star wheel 24 will force the ball outwardly in a direction normal to the notch side engaging the ball. Thus, rotation of the star wheel in a counterclockwise direction will shift the ball 35 against the plunger 30 and clockwise rotation will shift the ball against the right plunger 31. It will be understood that the plungers 30 and 31 arespring biased inwardly as explained hereinafter, and the ball will be forced up to shift the plunger outward a sufficient distance until the ball is able to roll over the point 27 between adjacent notches and then pass downward into the next notch and allow the plunger to return to the normal position.

The switching mechanism and arrangement for biasing the plungers 30 and 31 is mounted on the upper end of the housing on an integral projection 36. Inner leaf springs 38 and 39 are secured adjacent to the sides of the projection 36 and extend downward to rest against the sloping sides 37 of the housing 20 adjacent the outer ends of the plungers. These leaves 38 and 39 are relatively thin and resilient and serve to bias the plungers toward the inward position while being yieldable upon outward movement of the plunger to allow the contacts to close. Outward of the leaves 38 and 39 adjacent the projection 36 are a pair of insulating spacers 40 and 41, against the outer surfaces of which are mounted outer leaves 42 and 43 which preferably have greater thickness than inner leaves for greater stiffness against deflection. The outer leaves 42 and 43 extend substantially parallel to the inner leaves at all points and at their lower ends carry contacts 42a and 43a to make electrical contact with mating contacts 38a and 39a on the inner leaves when the adjacent plunger deflects the inner leaf outward to move the adjacent contacts into engagement to allow an electric signal to pass between the adjacent inner and outer leaf.

Outward of the outer leaves 42 and 43 are additional insulating spacers 44 and 45 which are clamped by metal plates 46 and 47. Screws 49 pass through the entire assembly between the outer plates 46 and 47 with which they are engaged to clamp the complete assembly on the projections 36. The screws 49 are provided with insulating sleeves 50 so as to insure proper insulation of the leaves. It will be understood that the necessary electrical connections with the circuit may be made at the free ends of the leaves projecting beyond the housing projection 36 by soldering or any other suitable manner,

From the foregoing, it will be seen that the invention provides a switch assembly which may be mounted on a conventional rotary selector switch so that depending upon the direction of rotation of the switch shaft 12, the star wheel 24 will be turned so as to produce momentary closing of one of the adjacent contacts for each stepwise rotation of the shaft and star wheel. Since separate sets of contacts close with different directions of rotation, a signal is provided by the appropriate switching contacts to indicate the direction in which the shaft has been turned.

Turning now to FIG. 4, this circuit shows an application of the switch of FIGS. 13 applied to a four digit position register and arranged to produce actuation of contact relays upon the initial rotation of one of the direction sensing switches and to disconnect that switch and the remaining switches from further action after the initial closing of the switch contacts.

The circuit has four input register switches indicated at 51, '52, 53 and 54 corresponding to a four digital position register. These switches have merely been shown by schematic representation only since the actual circuitry of the register switches is not a part of this invention. Electric current is supplied to the circuit by lines 56 and 57 and a starting circuit is located in line 58 across lines 56 and 57. A start switch 59 of the momentary contact normally open type is connected across normally open contacts 60 actuated by a contact relay in line 58 indicated at ICR. In series with the contact relay 1CR are normally closed contacts 65 and 66 of contact relays 2CR and 3CR, respectively. Thus, when the starting switch 59 is depressed, the relay 1CR will be actuated to close the contacts 60 to maintain contact relay 1CR energized unless either of the contacts 65 and 66 are opened. The activation of relay ICR also closes contacts 67 and 68 to connect the lines '56 and 57 to provide energization of the rest of the circuit.

Each of the input switches 51-54 has a direction sensing switch associated therewith actuated by the common shaft and which may be considered for switching purposes as a single pole double-throw switch. This action can be attained by connecting together the two inner leaves 38 and 39 and these contacts indicated at 61, 62, 63 and 64 are connected to the line 56. When any of these switches are actuated by rotating the shaft in one direction, as by rotating the shaft to decrease the numerical value in the register, the contacts 61, 62, 63 and 64 make contact respectively at 61a, 62a, 63a and 64a to connect through line 70 to energize contact relay 2CR which is connected to the other line 57. Likewise, actuation of these switches by rotation in the opposite direction to increase the numerical value will make contact at 61b, 62b, 63b and 64b to connect through line 71 to energize contact relay 3CR which is likewise connected at its other side to the other line 57. It will be understood that only one of the switches 61-64 will operate to provide the sign or direction sensing signal and the circuit is arranged so that actuation of one of the switches and the subsequent energization of either 2CR or 3CR will render the circuit inoperative. This is accomplished by the contacts 65 and 66 in line 58 which open when either contact relay 2CR or 3CR is energized so as to de-energize relay 1CR to cause the opening of contacts 67 and 68 to prevent any further supply from lines 56 and 57 to the switches 61-64.

However, the contact relays 2CR and 3CR are preferably of the time delay type in which there is a slight delay after actuation before the contacts are operated so as to allow actuation of the signaling relays. The signaling relays are actuated by having the contacts 61a-64a connected through a line 72 and normally closed contact 74 of contact relay 4CR to contact relay 5CR which is energized by completing the circuit through line 78 which connects to the supply line 57. Likewise, the contacts 61b-64b are connected through line 73 and normally closed contact 75 of relay 4CR to energize 4CR which is also connected to line 78. Upon the energization of either of the contact relays 4CR or SCR, the appropriate one of the normally closed contacts 74 and 75 is opened, but before this is done on the basis of a make-before-break arrangement of the contacts, either of the appropriate contacts 80 and 81 of relays SCR and 4CR, respectively, are closed to maintain energization of the appropriate one of the relays through line 82 which connects to line 56.

Thus, when the circuit of FIG. 4 is designed to be used for providing a sign signal output by means of additional contacts on either of the contact relays 4CR or SCR, the switch system is actuated by closing of the switch 59 to energize relay 1CR in line 58. This allows energization of the contact relays 2CR and 3CR when the appropriate one of the switches 61-64 is actuated by changing the setting of the input switches 51-54. Upon the movement of any one of these switches, the appropriate one of the switches 61-64 is actuated to close one of its contacts to thereby energize either of the contact relays 4CR or SCR and provide the appropriate sign or direction signal. To prevent any further signal which would actuate the other relay, after the short time de-,

lay, either relay 2CR or 3CR operates to open either of the contacts 65 or 66 in line 58 so thatrelay 1CR drops out thereby opening the contacts 67 and 68. Since one of the relays 4CR or SCR has been energized through the lines 78 and 82, the opening of the contacts 67 and 68 does not affect these relays which will continue to be energized until de-energized by the completing of the cycle.

Although the invention has been described in detail as to both structure and mode of operation, it is recognized that it is not limited to the structural details shown and modifications and rearrangements which will readily become obvious to those skilled in the art upon comprehension of this invention remain within the scope of the invention as defined in the claims.

I claim:

1. A directional responsive electrical switch comprising a housing, a shaft rotatable in said housing, cam means carried by said shaft, cam follower means contacted and operated by said cam means, first and second switch actuating means movably supported by said housing and each selectively contacted and operated by said cam follower means upon rotation of said shaft with the said selection being determined by the direction of said rotation, and first and second switches contacted and operated respectively by said first and second actuating means. 4

2. A switch as set forth in claim 1 wherein said cam means is a wheel having a plurality of radial notches with sloping sides on its periphery.

3. A switch as set forth in claim 2 wherein said actuating means are plungers slidable in said housing along an axis substantially normal to a sloping side of a notch when said cam follower means is interposed between the plunger and the sloping side.

4. A directional responsive electrical switch comprising a housing, a shaft rotatable in said housing, a cam wheel carried by said shaft and having a plurality of notches, cam follower means movably mounted in said housing in engagement with said notches for movement to and from said cam wheel, first and second switch actuating means movably supported by said housing and selectively engaged by said cam follower means upon movement of said cam follower means out of one of said notches, whereby rotation of said shaft in one direction causes said cam follower means to operate said first switch actuating means and rotation of said shaft in the opposite direction causes said cam follower means to operate said second switch actuating means, and first and second switches operable by said first and second switch actuating means.

5. A switch as set forth in claim 4 wherein said first and second switches are of the momentary contact type.

6. A switch as setforth in claim 4 wherein said first and second switch actuating means are plungers slidably mounted in said housing, each along an axis substantially normal to a sloping side of a notch when said cam follower means is interposed between the plunger and the sloping side.

7. A switch as set forth in claim 6 wherein said notches are V-shaped and have an included angle of substantially degrees.

8. A switch as set forth in claim 4 wherein said switches include leaf spring contact members which bias said switch actuating means and said cam follower means into engagement with the notches of said cam wheel.

9. A switch as set forth in claim 4 wherein said cam follower means is a ball.

10. A switch as set forth in claim 6 wherein said notches are on the radially outer periphery of said cam wheel, and said plungers are movable in the plane of said cam wheel.

References Cited UNITED STATES PATENTS 647,291 4/1900 Chapman 200-l53 2,427,453 9/1947 Hadley 200-61.39 2,767,268 10/1956 Levine ZOO-61.39

ROBERT K. SCHAEFER, Primary Examiner.

M. GINSBURG, Assistant Examiner.

US. Cl. X.R.

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