US2902685A - Position indicating circuit - Google Patents

Description

iarlio interference. p 7 '-Accordingly, a principal objectof this invention is to United States Patent POSITION INDICATING CIRCUIT Edward A. Davis, Harwichport, Mass. Application February 9, 1954, Serial No. 409,065

3 Claims. "(CL 340-332) This invention relates to an electrical switching system for position-indicating devices and more particularly relates to a switching system for use in an electric wind indicator, such, for instance, as is disclosed in my Patents 'No. 2,266,172, and No. 2,744,972, issued December 16, 1941, and May 8, 1956, respectively.

In the wind indicators of my said patents, the switching system includes a series of stationary, closely spaced, electrical switch contacts insulated from each other and in separate circuits. In each of these circuits is an incandescent lamp, the lamps being arranged in the pattern of a compass so that each lamp indicates a difierent particular compass direction. The system also includes amovable switch contact which is moved by a weathervane in accordance with the weathervanes movement and brushes over and contacts the stationary contacts to light the lamps as located in their pattern to corre pond 'to'the compass direction of the weathervane. The stationary contacts are so close together that the movable contact 'inmoving from one stationary contact to the next will contact the next contact before breaking contact with the contact which it is leaving. As a consequence, every time the movable contact moves from one stationary contact to the next, two lamps show light simultaneously and stay lit until the movable contact breaks contact with the preceding contact. 7 in circuits where-a movable contact bridges two other separate contacts and closes their circuits, when the movablecontact leaves one of said other contacts an electric arc' occurs at the break, and such arcs can cause difficulties such as electrical erosion and oxidation of the contact Surfaces, requiring the use of relatively expensive noble p metals to avoid :such oxidation due to arcing. Further,

such electrical erosion shortens the life of the contact materirl by burning it up. The surface oxide itself can block thefcurrent, causing failure of the indicating system, and also the'powder'y oxide particles and other products of the are can hold the contact surfaces apart and prevent the closing ,ofthe circuit. .In addition, the arcing causes provide a'n electrical switching system having .a plurality of circuits with individual contacts and a common contact moyableiiito contact with said individual contacts in succession and bridging two successive individual contacts when msvm 'rmm brieto the other. In this system the tendency of an are being formed when the movable conj tact makes or breaks contact with any of the individual contacts, is substantially eliminated.

Also in prior electrical rotary switching systems, and commonlyin thoseemplo'yed in electric Wind direction indicators, incandescent lamps are used of so low a voltage that a step down transformer is required when the household or commercial power of from 110 to 220 volts is used; in such wind indicator circuits a condenser may 2,902,685 Patented Sept. 1,, 1959 Another principal object of this invention is to provide an electrical switching system suitable for employment in a wind direction indicator and which system includes a rotary switch energizing selectively separate indicating circuits in correspondence to wind direction, or under other control, and for which system power of a common voltage, such as from 1-10 or 220 volts may be used without requiring any step-down transformer.

Another object of this invention is to provide an electrical switching system of the character stated using indicating lights and in which the light producing elements have a considerably longer life than is the life of the light elements previously employed in such systems.

Another object of this invention is to provide an electrical switching system of the character stated and which does not require the employment of condensers to eliminate radio and television interference.

A further object of this invention is to provide an electrical switching system of the character stated which is simple in construction, sturdy, durable and inexpensive, operates efiiciently and positively, and may be employed effectively as an improvement in the electrical switching system of the direction indicator disclosed in my said Patent No. 2,266,172, or in other switching circuits or systems.

Other objects of this invention will be in part obvious and in part pointed out hereinafter.

In accordance with this invention the electrical switching system includes, as former circuits have included, a plurality of contacts in the nature of distributor .points each in a difierentenergizable indicating circuit, and another contact which is common to and adapted to move into contact with said distributor points singly to'energize a circuit therethrough. The movable contact when moving from one point to the next makes contact with said next contact before breaking contact with the preceding point. 'Whereas in these prior systems incandescent lamps were used for the energizable indicating lights and two lights would be lighted when the contact bridged two distributor points, my invention employs electrondischarge lamps instead of incandescent lamps, the normal starting voltage of the electron-discharge lamp being more than one-half of the voltage of the current power supply connected to the circuit, so that when the contact is in contact with one distributor point and establishes a circuit therethrough to light the lamp therein and then moves to have contact also with the next distributor point it will not cause the lamp in the next circuit to light until the contact has broken with the previous distributor point. This is due to the fact that the neon tube of the previous circuit is using more than one-half of the available voltage and there is insuificient voltage left available to cause the neon lamp in the next contacted circuit to light, or start, until the contact has broken with the previous distributor point. Consequently, in accordance with this invention, when the contact moves to a second distributor point before leaving a first point or when the contact leaves the first point While in contact with the second point there will be little or no arcing in either case because when the contact engages the second point there is not enough voltage available to cause current to flow through the second distributor point, and then when the contact leaves the first distributor point the full current can flow through the already closed circuit of the second distributor point and no current flow takes place to cause arcing at the first distributor point. Since full normal voltage of say or 220 volts can be used to start the neon lamps and to keep them lighted singly, no step-down transformer is necessary. It is well recognized that the glow lamp must be operated in series with current limiting means thereby prolonging its useful life; and the present invention makes no exception to this principle of operation requiring resistors in series. To this end a ballast resistor can be incorporated in either line 15 or 16.

The particular environment in which the system and circuit of my invention may be beneficially employed is not restricted necessarily to a. wind direction indicator and may find utility in other environments to indicate position remotely.

The invention, accordingly, consists in the features of construction, arrangements of parts, and operation of the system, which will be described more fully hereinafter and the scope of the application of which will be set forth in the claims that follow.

In order that a clearer understanding of this invention may be had, attention is hereby directed to the accompanying drawings, forming a part of this application, and illustrating certain possible embodiments of this invention, and in which:

Figure 1 is a diagrammatic representation of the circuits through the signal lamps, distributor contacts and the movable contact; and

Figure 2 is a diagrammatic representation of weathervane means for moving the movable contact over the distributor contacts;

Similar reference characters refer to similar parts in the two figures of the drawings.

Referring to the drawings, the electrical switching system includes a plurality of contacts 10, comprising contacts a, 10b, 10c, 10d, 10c, 101, 10g and 10h, insulated from each other. The system also includes a number of neon lamps 11, comprising lamps 11a, 11b, 11c, 11d, He, 111, 11g and 11h, corresponding in number to the number of the switch contacts 10. Different ones of the contacts 10 are connected to different ones of the lamps 11 by conductors 12. For instance, conductor 12a connects contact 10a to lamp 11a, conductor 12b connects contact 1012 to lamp 11b, conductor 12c connects contact 100 and lamp 110, conductor 12d connects contact 10d to lamp 11d, conductor 12c connects contact 10c to lamp lle, conductor 12 connects contact 10 to lamp 111, conductor 12g connects contact 10g to lamp 11g, and conductor 11h connects contact 1012 to lamp 11h. Thus, there are eight separate circuits established between the eight separate contacts 10 and the eight corresponding neon lamps 11, a diiferent contact and a different lamp being in each circuit.

The system also includes a contact 13 which is common to all of the stationary contacts 10 and is movable from one contact 10 to the next adjacent contact, the stationary contacts 10 being so spaced apart and the movable contact 13 being of such span or width that the contact 13 may make contact with only a single contact 10, but when moving from one contact to the next, the contact 13 will contact the contact 10 which it is approaching before it leaves the contact 10 which is leaving.

The movable contact 13 is connected by a conductor 14 to one lead 15 of a source of electrical current supply and the lamps 11 are connected by conductor 16 to the other lead of the current supply.

The voltage of the system circuit and the normal starting voltage of the neon lamps are such that the normal starting voltage of the neon lamps is greater than one-half the voltage of the system circuit. Accordingly, when a lamp 11 has been lighted by the contacting of the movable contact 13 with a single contact 10, and the movable contact moves into engagement with the next contact point 10, the light corresponding to said next contact point will not light because the circuit of the lighted lamp takes so much of the voltage of the circuit that there is insufficient voltage in the circuit to light the lamp in the circuit of said next contact. Consequently, when the movable contact 13 makes contact with a second contact 10 before breaking contact with a previous contact 10, there will be no arc formed because no current flows between the movable contact and said second contact upon such contact being made, and since the movable contact 13 is already in contact with said second contact 10 when the movable contact breaks contact with the previous contact 10 no arc will be formed since the circuit is already closed through the second contact. The disadvantages incident to arcing at the contacts caused by movement of the movable contact 13 over the stationary contacts 10 are thus largely eliminated. Further, only a single lamp 11 will be lit at any one time, since there is never more than one of the separate lamp circuits energized at any time, although when the movable contact moves from one stationary contact to another contact the circuits including those two contacts are closed, but only the first closed circuit is energized.

It is apparent that an electrical switching system as set forth above is useful in many different environments in which there are a plurality of separate circuits to be energized separately and never two at any one time, and in which arcing at the switch contacts is to be avoided. For example, as stated, this electrical switching system is useful in an electric wind indicator, such, for instance, as disclosed in my said Patent No. 2,266,172. When included in such a wind indicator the movable contact 13 is moved by and in correspondence with a weathcrvane which has a vane 17 secured to a shaft 18 which rotates therewith, and the contact 13 may project from a collar 19 which is secured to shaft 18 to rotate therewith. The stationary contact points 10 are mounted in a dielectric housing 20, the contact points 10 having jacks 21 extending below the housing 20 and to which the conductors 12 are attached. The shaft 18 and housing 20 are shown mounted on a suitable base or frame 22.

The stationary contacts 10 are arranged and oriented to correspond with different compass positions to which the weathervane may be swung by the wind, and the lamps 11 are correspondingly arranged and oriented so that each lamp, when lit, will indicate from which direction the wind is blowing, as is well known in the art.

In operation, when the movable contact 13 is in contact with only one of the contacts 10 the corresponding lamp is lit. Then when contact 13 moves to an adjacent contact 10 the light corresponding to the adjacent contact 10 does not light until the contact 13 breaks contact with the previous contact and that light goes out; because until that time there is not sufiicient voltage available in the circuit to light the lamp corresponding to the contact secondly contacted. At the same time, there is little or no arcing at the contacts at any time for the reasons set forth hereinbefore.

As many changes can be made in the uses of the electric switching system embodying this invention, and in the construction of wind indicators in which the system may be used, it is understood that all matter contained in the above description or shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In an electrical switching system of the character described, a plurality of separate electric circuits, each having therein a switch contact and an electron discharge lamp individual thereto, said contacts being insulated from each other, a contact common to and movable over said switch contacts into electrical contact therewith successively, the contact span of said common contact and the spacing of said switch contacts from each other being such that said common contact may be in contact with only one switch contact and in moving from a switch contact to an adjacent switch contact makes contact with the adjacent switch contact before breaking contact with the previously contacted switch contact, a source of electric current supply, main circuit means connecting said supply on one side to said common, movable contact and on the other side to said separate circuits, current limiting means in series with one said main circuit means, said electron discharge lamps having the same normal dialling voltage rating of more than one-half of the voltage of said current supply, whereby only one of said lamps will be lit at any time during the operation of said movable contact.

2. An electrical switching system as set forth in claim 1, which includes power means connected to said movable contact said power means being adapted to move said movable contact over said switch contacts.

3. In an electrical switching system of the character described, a plurality of switch contacts arranged in succession and insulated from each other, a plurality of electrical circuits, each having a different one of said switch contacts and a neon or electron discharge lamp therein, said lamps having a similar predetermined normal voltage rating, a common contact common to all of Said circuits and movable into and out of electrical contact With said stationary contacts in succession, means for moving said common contact across said switch contacts in succession, adjacent switch contacts being spaced so close together and the common contact being so wide that the common contact makes contact with two successive 20 switch contacts as the common contact moves from one switch contact into contact with the next adjacent switch contact, a common source of electrical energy for all of said circuits and having a voltage less than double said normal lamp voltage, main circuit means connecting said source to said circuits, and current limiting means in series with said main circuit means, whereby when the common contact moves into contact with a switch contact before breaking contact already made with an adjacent switch contact, no current will flow through the circuit of the laterally contacted switch contact until the common contact has broken contact with the firstly contacted switch contact, and thereby arcing at either of said contacts is substantially avoided.

References Cited in the file of this patent UNITED STATES PATENTS 1,887,684 Huizinga Nov. 15, 1932 1,954,313 Fuller Apr. 10, 1934 2,266,172 Davis Dec. 16, 1941 2,568,348 McCauley Sept. 18, 1951 FOREIGN PATENTS 247,953 Great Britain Mar. 10, 1927

Images