US3385943A - Electric signal code generator - Google Patents

Description

y 23, 1968 E. A. WESTPHAL 3,385,943

ELECTRIC SIGNAL CODE GENERATOR Filed May 2. 1967 2 Sheets-Sheet 1 :fls [9 2| [6 l7 FIG. I FIG. 2

INVENTOR EVERETT A. WESTPHAL 4 WM, f/hfim,

HIS ATTORNEYS May 28, 1968 E. A. WESTPHAL ELECTRIC SIGNAL CODE GENERATOR 2 Sheets-Sheet ti Filed May 2, 1967 FIG FlG

INVENTOR L A H P T r s E W i S Y E T N T R E m R 7 WW s H Y B United States Patent "ice 3,385,943 ELECTRIC SIGNAL CODE GENERATOR Everett A. Westphal, Lafayette, Calif. (325 7th t, Oakland, Calif. 94607) Filed May 2, 1967, Ser. No. 635,562 5 Claims. (Cl. 200-166) ABSTRACT OF THE DISCLOSURE An electrical signal code generator wherein an electrical circuit is interrupted according to a desired pattern includes a wheel carrying two mutually insulated contacts, at least one of which is a ring of separated contacts wiped by a brush, each of which is connected to a second contact element on the wheel by severable electrical connectors which can be selectively severed, as by drilling, to break the connection and form a desired code. The second contact element can be continuous or interrupted and can be wiped by a second brush or have external electrical contact through the wheel axle. Several pairs of such contacts can be provided to adapt the wheel to an alarm system, e.g., suitable for use in a McCulloh loop.

The invention relates to an electrical signal code generator which can make and/or break an electrical circuit in accordance with a desired pattern to generate a code in one or in a plurality of circuits. More particularly, it relates to a generator of the type having a wheel which is rotatable relatively to one or more brushes which wipe electrical contacts on the wheel, wherein the wheel can be easily altered to generate any of a large number of codes.

The invention is applicable, for example, to alarm systems in which a plurality of remote subscribers premises to be protected from burglary, fire, or the like are connected by electrical circuits, such as telephone lines or radio channels, to a central office whereat the signals are received and recorded in the vent of an unauthorized entry or a fire at the subscribers premises. In a special application, each of the subscribers lines is connected to the central otfice by what is known as a McCulloh loop circuit. This circuit, being well known, will not be described herein in detail; it includes, at the central oflice, an electrical storage battery, the positive side of which is grounded and which is connected at both sides through coils of relays to the line, these relays being connected to recognize either the opening or the grounding of the circuit. Several subscribers lines are connected to a common central ofilce receiver and recorder, for example, connected in series, and the identity of the subscriber emitting a signal is recognized by the particular code. In this system, each code generator at a subscribers premises has a circuit switch which is normally closed so that opening or grounding of the circuit at any subscriber will be manifested at the central office.

In the code generators used heretofore, each mechanism included a pair of spring arms controlling switchpoints, of which one was normally closed and the other, leading to ground, was normally open, these switches being actuated by a cam wheel having a series of notches arranged according to a predetermined pattern. In the event of any unauthorized opening of a circuit at the subscribers premises, a relay at those premises becomes tie-energized, which thereby energizes a motor drive to operate the notched wheel, causing the switches to send coded pulses over the telephone line to the central ofiice registers.

A drawback of the known code generating switch mech- 3,385,943 Patented May 28, 1968 anism has been the need to provide a large number of different cams for actuating the switches or the difiiculty in cutting a cam wheel having properly spaced notches for each installation. It is evident that when several subscribers are connected in series each must have a different code.

A further drawback has been that the cam mechanism does not always produce pulses of uniform duration or occurring at precisely predetermined intervals. Thus, a slight misalignment of the drive shaft of the notched wheel or a slight deformation of the spring fingers which cooperate with these notches leads to nonuniform operation. This has required the spring arms to be carefully adjusted at each installation, which is a time-consuming operation. Moreover, such mechanisms are subject to rapid wear and frequent servicing is necessary.

According to the present invention, these drawbacks are avoided by providing a code generator having a wheel in which any desired code can be readily set up by merely severing connections between electrical contacts on the wheel. The dimensions of these contacts can be carefully controlled during manufacture, leading to improved uniformity of pulses. Moreover, such a device does not need any adjustment and, by providing the contacts with suitable wear-resistant surfaces, a long service life is assured.

In summary, according to the invention, the code generator includes a wheel carrying at least one pair of contacts, of which at least one is a ring of separated contacts wiped by a brush, each of said contacts being connected to a second contact element (which may be continuous or discontinuous) by a severable electrical connector which is adapted to be easily cut, as by drilling, to break the connection between the separated contact and the second contact on the wheel. The second contact element may also be wiped by a brush or, if desired, an electrical circuit thereto can be established through the shaft of the Wheel. Several pairs of such contacts can be provided to adapt the wheel to an alarm system suitable for the above-mentioned McMulloh loop. There must, of course, be relative rotation between the wheel and the brushes; however, it is not essential that the wheel ro tate, it being also possible to employ a stationary wheel and to rotate the brushes mounted on a suitable pivoted arm.

To facilitate severing the electrical connectors, each is preferably provided with a depression for guiding its severing implement, e.g., each such connector may have a depression for receiving the point of a small drill which is used to cut away the connection.

Advantageously, the wheel is a flat disc and the contacters are applied thereto by any known printed circuit technique. Preferably, all contacts that are wiped by brushes are further plated to make them wear-resistant.

The invention will be further described with reference to the accompanying drawing forming a part of this specification and showing two preferred embodiments, wherein:

FIG. 1 is an elevation of the code-generating device, a part of the base being shown in section;

FIG. 2 is an end view of the device;

FIG. 3 is a section taken on the line 3-3 of FIG. 1, showing the face of the code wheel, parts of the connecting circuit being shown;

FIG. 4 is an enlarged, fragmentary view of a part of the code wheel;

FIG. 5 is a plan of a code wheel [according to a modified embodiment;

FIG. 6 is a plan of the reverse side of the wheel shown in FIG. 5; and

FIGS. 7 and 8 are fragmentary sectional views taken on the corresponding section lines of FIG. 5.

Referring to FIGS. 1-4, the code generator comprises a base plate 10 having journaled therein a drive shaft 11 which is connected to a suitable electrical motor (not shown) and is secured to a code wheel 12. A pinion gear 13 may be mounted on the shaft 11 for rotation with the wheel 12, e.g., by means of a pin 14 which extends through a hole in the wheel. The gear meshes with another gear (not shown) for controlling the operation of the drive motor. The parts 10 and 12 may be made of any suitable, rigid, insulating material, such as plastic or insulating board. The base 10 carries a plurality, e.g., four brushes 15-18, which are mounted in pairs on soldering lugs 19 and 20 which are fastened by rivets to the base 10. These brushes may be Phosphor-bronze wires and extend through holes 21 in the base to engage the face of the wheel 12. These brushes may, for example, have loops at their ends to present convex contact regions and bear against the wheel resiliently with a pressure of about 2 grams. The pin 14 may be grounded to provide a fifth electrical circuit to the wheel face.

The face of the wheel 12 against which the brushes 15-18 bear is provided with suitable contacts which may be applied by the printed-circuit technique, e.g., being formed principally of copper coated with a wear-resistant material, such as nickel, as needed. However, the invention is not limited to this specific construction, and the contacts may be cut from a metallic sheet and applied to the wheel face. Regardless of the technique of manufacture, the contacts provide the following, which will be de scribed in a specific relationship relatively to the distance from the periphery of the wheel, although the sequence can be varied as desired At the outside is a ring of separated contacts 22, positioned for engagement by the brush 18 and separated circumferentially by insulated sections 23. Inside of this ring is a continuous ring 24, positioned to make continuous contact with the brush 16 and having a plurality of radially outwardly extending contact sections 25 positioned to make intermittent contact with the brush 17. Each of the contacts 25 is connected by a severable metallic connector 26 to a corresponding separated contact 22. Thereby all of the several contacts heretofore described are initially interconnected electrically. Each connector 26 has a guide recess, such as a small tapered depression 27, for guiding the point of a drill. When a drill is placed into a recess 27 and a hole is drilled partly into the wheel 12, the connector 26 is severed, as indicated at 27a in FIG. 4.

The wheel further has a central metallic area 28 which is electrically connected to the pin 14 to establish a ground circuit, and has a plurality of radially outwardly extending contacts 29 positioned for wiping engagement with the brush 15. Each contact 29 is connected electrically to the part 28 by a severable connection 30, which is similarly provided with a recess 31. When a drill is applied to the recess 31, the contact 29 is severed from the region 28, as appears at 31a.

The shaft 11 rotates to drive the wheel in the direction indicated by the arrow 32, and each contact 22 has a leading edge 33 which is aligned radially with the trailing edge 34 of a preceding contact 25. Similarly, each trailing edge 35 of a contact 22 is aligned radially with the leading edge 36 of the corresponding contact 25. It will be understood that this alignment is appropriate for the embodiment shown, wherein the several brushes 1518 are situated on a common radial line; further, the contacts 25 may be slightly wider than indicated. The arrangement, in any case, when employed for use in a McCulloh loop circuit, is such that the brush 17 engages the contact 25 not after the brush 18 disengages the corresponding contact 22, and that the brush 17 breaks contact with the contact 25 not before the brush 18 engages the next contact 22. Similarly, each contact 29 is aligned with the outer contacts so that the brush 15 engages the contact 29 somewhat before the brush 17 engages the contact 25 and disengages the contact 29 somewhat before the brush 17 leaves the contact 25.

A portion of the circuit which receives the code is illustrated in FIG. 3, wherein the brushes 17 and 18 are connected to one side L-l and the brushes 15 and 16 to the other side L-2 of a telephone line leading to the central oflice. (When several subscribers are connected to a cornmon central ofiice, additional code generators may be connected serially into this telephone circuit.) The central office has relays of which only the windings RY-l and RY2 are shown, these relays being further connected to a battery B of which the positive side is gounded.

In operation, the wheel 12 is normally stationary at a home position at which the brush 15 engages an insulated area between the contacts 29, the brush 17 engages an insulated area between the contacts 25, and the brush 18 engages one of the contacts 22; the brush 16 always engages the contact 24. When the wheel 12 rotates in the direction of the arrow 32, the brush 15 engages the contacts 29 in succession. Upon engaging those contacts 29 at which a hole 310 was formed to sever the connector 30, the brush 15 remains ungrounded; however, when the brush engages one of the other contacts 29, it is temporarily grounded, thereby de-energizing the relay winding RY2. Also, in the cases of the connectors 26 which do not have holes 27a drilled out, either the brush 17 or 18 will be electrically connected to a contact 25 or 22, respectively, whereby the circuit L-1 is connected to the circuit L-2 via the brush 16 :and the contact 24. However, when the brush 18 engages a contact 22 which has its connector 26 severed by a hole 27a, the circuit L-1 is disconnected from the circuit L-2, thereby causing both relays RY1 and RY2 to become de-energized.

It is evident that by selectively severing the connections 26 and 30 a large variety of codes or patterns of signals can be provided in the same code wheel, and that this is easily done by the mere use of :a rotary drill.

The invention may be otherwise embodied, and the severable connectors may take other forms. For example, in the embodiment shown in FIGS. 5 through 8, the code wheel 112 has an outer ring of separated contacts 122, a circumferentially continuous contact ring 124 having radially outwardly projecting contacts 125, and an inner ring of circumferentia-lly separated contacts 129, all fixed to one face thereof and formed as previously described. Reference numbers in this embodiment denoting parts which correspond to those of the first embodiment are increased by one hundred, and the wheel 112 is designed to cooperate with four brushes similarly aligned along a common radial line. The reverse side of the wheel 112 carries a continuous metallic conducting ring 135. Each of the contacts 122 is electrically connected to the ring 135 by a tubular connector 126 having flared outer ends which provide tapered recesses 131. The connectors 126 can be selectively removed by drilling completely or partly through the wheel so as to sever the electrical connection between the parts 122 and 135. When the wheel is drilled entirely through, the connector 126 is removed, leaving a hole 131a, as appears in FIG. 8. The ring 135 is connected to the continuous contact 124 by a similar tubular connector 136. The contacts 129 are electrically connected to a metallic, conductive area 128 on the reverse side of the wheel by tubular connectors 130, which are constructed exactly as previously described for the connectors 126. These can be selectively drilled out to sever the connections 130 and separate the contacts 129 from the conductive area 128. It will be understood that the area 128 is suitably connected to an external circuit, e.g., is grounded as described for the area 28 in the first embodiment.

The wheel 112 has the various contacts placed in coordinated positions in accordance with the desired function, e.g., as described for the first embodiment, and is rotated in the direction indicated by the arrow 132. It is evident that the operation is the same, and that any desired code can be generated in accordance with the numbers and locations of the connectors and 130 which are severed.

Although severable electrical conductors were described in connection with the preferred embodiment, it is evident that the opposite may be used. Thus, the code wheel of either embodiment may be initially manufactured with the connections absent, and these can be added in setting up the desired code, as by applying a drop of solder to bridge the unconnected contacts in the first embodiment or by inserting the tubular connectors 130 as necessary.

I claim:

1. An electrical signal code-generating system which comprises: first and second brushes, a code wheel rotable relative to said brushes, first and second mutually insulated contact rings on said Wheel situated to make electrical contact respectively with the first and second brushes, at least the first ring being discontinuous to form a series of contacts separated by insulated sections, and electrically conductive means interconnecting said contacts to said second ring, said conductive means being the only electrical connections between said rings and being selectively severable to thereby establish a desired code of sequential circuit interruptions between said brushes upon relative rotation of said wheel and brushes, said separated contacts having the trailing edges thereof spaced from the leading edges of the respectively next contacts by insulated sections greater in length than the contact length of said first brush, said wheel including a third electrically conductive ring of contacts, said ring being electrically connected to said second ring, and a third brush positioned for electrical contact with said third ring, the contacts of said third ring having leading edges positioned in coordinated relation to the separated contact, whereby rotation of said whee-1 relative to said brushes causes a predetermined series of circuit interruptions to thereby establish a signal pattern.

2. The apparatus set forth in claim 1, wherein the leading edge of each contact of said third ring is situated in relation to the positions of said first and third brushes and of said separated contact so that the contact of the third ring makes contact with the third brush not after the first brush breaks contact with the separated contact and breaks contact with the third brush not before the first brush makes contact with the next separated contact.

'3. The apparatus as set forth in claim 1, wherein said conductors comprise strips of metal interconnecting each contact of the third ring with corresponding separated contacts.

4. The apparatus as set forth in claim 1, wherein the contacts of said third ring have radial leading and trailing edges, said edges being aligned radially respectively with the trailing edge of a separated contact and with the leading edge of a succeeding separated contact.

5. The apparatus as set forth in claim 1, wherein a fourth brush is provided, said wheel having a fourth ring of circumferentially spaced contacts, said fourth ring being positioned for successive electrical contact with said fourth brush, a comm-on electrical circuit, and severa- -ble electrical conductors connecting each of said contacts of the fourth ring with said common circuit.

References Cited UNITED STATES PATENTS 3,148,438 9/1964 Winter et al 29-626 3,204,236 8/ 1965 Duris et al 340-345 3,261,929 7/1966 Neff 20011 3,293,399 12/1966 Heinrich 200166 3,320,391 5/1967 Lafont 200166 FOREIGN PATENTS 973,975 t1 1/ 1964 Great Britain.

ROBERT K. SCHAEFER, Primary Examiner. H. O. JONES, Assistant Examiner,

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