US2601250A

US2601250A - Safety mechanism for doors

Info

Publication number: US2601250A
Application number: US208164A
Authority: US
Inventors: Bruns William Henry; Davis Samuel
Original assignee: Otis Elevator Co
Current assignee: Otis Elevator Co
Priority date: 1951-01-27
Filing date: 1951-01-27
Publication date: 1952-06-24
Anticipated expiration: 1969-06-24

Description

June 24, 1952 w. H. BRUNs l-:TAL 2,601,250

SAFETY MECHANISM FOR DOORS Filed Jan. 2'?, 1951 4 Sheets-Sheet l June 24, 1952 Filed Jan. 27, 1951 w. H. BRuNs ET AL 2,601,250

SAFETY MECHANISM FOR DOORS 4 Sheets-Sheet 2 a2 a0 0105 l 1m DPT 102103 C5 'Z4 lo@ l W/LL/HHENYPl/NS INVENTGRS ATTORNEY June 24, 1952 w. H. BRUNS ETAL SAFETY MECHANISM FOR DOORS 4 Sheets-Sheet 3 Filed Jan. 27, 1951 S R m N E v m S N UQ Mo Ha Ma mn L4 H ,J W :I

BY ATTO R N EY June 24, 1952 w. H. BRUNS ET AL SAFETY MECHANISM FOR DOORS Ti III |1175.

Filed Jan. 27, 1951 FIGJO Patented June 24, 1952 UNITED STATES PATENT OFFICE SAFETY MECHANISM FOR DOORS of New Jersey Application January 27, 1951, Serial No. 208,164

20 Claims. 1

The invention relates to safety mechanism for protecting against closing doors, such as power operated doors of elevator installations.

It is common practice in present day elevator installations to effect closing of the doors automatically. In passenger installations in which the starting of the car is under the control of an attendant, the attendant also acts as a guard to prevent passengers being struck by a closing door. However, this is not the case in installations in which the car is started automatically as, for example, where both the starting and stopping of the car are under the control of the passengers themselves. In many of such installations in which the car door or both the car door and hoistway doors are power operated, safety devices have been provided for stopping the closing of the door when a transferring passenger or an inanimate object is or is about to be struck. Depending on the arrangement, this softens the blow, or obviates the person being struck, thereby minimizing the possibility of real injury. These devices are applicable to door operating mechanism in which the power mechanism acts directly to close the door or in which the power mechanism includes a spring which acts to close the door. There are certain advantages in the latter arrangement, for should a person be struck he is subject only to the force of the closing door and its spring.

One object of the invention is to provide safety mechanism which detects the presence of a person or object while the door is still a considerable distance away so that the possibility of the person or object being struck is minimized.

Another object of the invention is to provide safety mechanism of the above character which is not readily apparent to users of the entrance, which has no moving parts and which is reliable in operation.

The invention involves electronic safety mechanism in which one or more electronic tubes, preferably cold cathode gas tubes, are caused to break down in response to the presence of a person or object in a eld of influence of the mechanism and in so doing act to prevent the closing of the door or, in the event the door is closing, to prevent further closing of the door and bring it to a stop.

In carrying out the invention according to the arrangement which will be described, a plurality of cold cathode gas tubes are mounted at vertically spaced intervals along the leading edge of the door. In the case of center opening doors,

tubes are mounted along the leading edge of ff.;

each door. These tubes act when a person or object is within a certain distance of the door in or near the entrance to control the closing of the door. To provide a continuous zone of iniluence of a sucient height, each tube is provided with an antenna which covers a vertical section of the zone of iniiuence in proportion to the number of tubes. To prevent unwanted operations and to properly extend and shape the Zone of influence horizontally, electric shields are provided. A source of current is provided for the anode-cathode circuit of each tube, the voltage value of which is above sustaining voltage of the tube but insuflicient to break down the tube. A periodic source of current is provided for firing the tubes. This source is connected to the tubes so as to fire any one of them upon suflicient change of capacity to ground of the antenna for that tube brought about by the presence of a person or object within a certain distance of the antenna. The tubes are connected in door control circuits such that the firing of any tube prevents the closing of the door 0r if the door is closing interrupts the closing to bring it to a stop and returns it to open position. When the car and hoistway doors are arranged to close in unison, it is preferred to provide the control tubes only on the car door and to arrange their antennae and shields so as t0 extend and shape their zone of inuence at an angle suilicient to protect also against the closing of the hoistway doors. Also the antennae and the car door shield are arranged so as not unduly to extend the zone of influence into the car, thus preventing unwanted operations when passengers stand near the car door.

Features and advantages of the invention will be apparent from the above statements and from the description which follows and appended claims.

In` the drawings:

Figure 1 is a somewhat simplied view in front elevation of an elevator car with the car door and associated hoistway door embodying the invention;

Figure 2 is a plan view of the arrangement of the car door and hoistway door of Figure l;

Figure 3 is an enlarged detail in front elevation illustrating the protective mechanism along the front edge of the car door of Figure 1, with the door abutting the strike jamb;

Figure flis a view similar to Figure 3 without the strike jarnb illustrating the interior of the channel in which the detecting tubesl and anterme@ are mounted;

Figure is an enlarged detail taken along the line 5-5 of Figure 3;

Figure 6 is an enlarged detail taken along the line 6-6 of Figure 3;

Figure 7 is an enlarged detail taken along the line 1-1 of Figure 4;

Figure 8 is a View in elevation of the rear of the hoistway door of Figure l;

Figure 9 is an enlarged detail taken along the line 9 9 of Figure 8;

Figure l0 is a simplified schematic wiring diagram of that portion of the elevator power and control circuits which relate to the control of the doors of the elevator installation; and

Figure 10s is a key sheet for Figure 10 showing the electromagnetic switches in spindle form.

Referring rst to Figure 1, the elevator car I I is illustrated as positioned at a landing I2. The car door I3 and hoistway door I4 for that landing are illustrated in closed position. While it is to be understood that the car door and hoistway doors may be operated in various ways, an arrangement has been illustrated in which these doors are power opened and spring closed. Two speed, side opening doors have been illustrated but it is also to be understood that the invention is applicable to other arrangements, especially center opening doors. Solid panel door sections are provided and are supported in the usual manner by hangers, not illustrated.

The car door and hoistway doors are operated by a door motor DM mounted on cross member of the car framework 2|. This motor operates through a gear reduction arranged in casing 22 to drive a shaft 23 upon which an operating cam 24 is mounted. This cam operates a lever 25 through the intermediary of a roller 26 secured to the lever at an intermediate point in position to roll on the face of the cam. Lever 25 is pivotally mounted at one end 0n casing 22 and has a chain 21 connected to its other end for effecting operation of the car door. At its other end, chain 21 is connected to a lever 3D secured to a shaft 3I rotatably mounted on the car framework. This shaft operates the car door operating arm 32 which is connected by way of a link 33 to the leading section 34 of the car door and by way of a link 35 to the other section 36 of the car door. A spring 31 is connected at one end through a chain to arm 32 and at the other end to a bracket 4I secured to the cross member 20. This spring acts through arm 32 to bias the car door to closed position. A pair of

door checks

42 and 43 are arranged for operation by shaft 3| to cushion the final opening and closing movements of the car door.

While it is preferred in actual practice to provide separate levers and cams for operating the car door and hoistway doors, for convenience this has been illustrated as effected by the single cam 24, lever 25 and roller 26. Another chain 44 is illustrated as connected to lever 25 from which it extends to a retiring cam 45, the chain passing over idler pulley 46 mounted on the cross member. The retiring cam is provided with a mounting plate 41 secured to the car framework. A pair of parallel links 50 .are pivotally mounted on plate 41 and are pivotally connected at their outer ends to the cam plate 5I. The cam plate is adapted when extended to engage roller 52 of bell crank lever 53 pivotally mounted on a bracket 54 secured to the building structure. The other end of this bell crank is connected by tie rod 55 to the operating arm 5S of a toggle lever 51, the arm 56 being pivotally mounted on a bracket 66 secured to the hoistway wall. This lever is pivotally connected at plate 6I and bracket 62 to the two

sections

63 and 64 of the hoistway door (see Figure 8). A spring 65 is connected at one end to bracket 60 and at its other end to a chain 65. in turn connected to a point on toggle lever 51 in position to be engaged by a cam 61 provided on the end of the intermediate arm of the toggle lever. This spring acts through the toggle lever to bias the door to closed position. A double acting door check 1I is connected for operation by arm 56 to cushion the final opening and closing movements of the hoistway door.

Limit switches are provided for controlling the operation of the door operating motor DM. For convenience it will be assumed that these switches are arranged in a casing 15 for operation as by cams rotated by shaft 23. These switches are shown in the wiring diagram, Figure 10. Car door and hoistway door contacts are not illustrated.

To open the doors, motor DM is energized for rotation in a direction to4 effect clockwise movement of shaft 23 and thus of cam 24. This pushes lever 25 clockwise which acts through chain 21 to pull lever 30 clockwise. Thus car door operating arm 3 2 is swung clockwise and acts through its link connections to the car door sections to open the car door. these connections being at such points that section 34 moves at twice the speed of section 36. Lever 25 also acts through chain 44 to lift retiring cam 45. Bell crank lever 53 is thus swung in a direction to push upwardly on tie rod 55. Thus toggle lever 51 is operated to break the toggle and to pull the hoistway door to open position, the points of connections of the lever to the door sections being such as to effect the movement of section 63 at twice the speed of section 64. As the doors reach open position, the door open limit switch in casing 15 causes deenergization of motor DM to bring it to a stop. The contour of cam 24 is such as to give the desired acceleration, speed, and retardation during opening movement of the doors, and as the doors reach open position their stopping is cushioned by their checks.

During opening movement of the doors, tension is placed in springs 31 and 65 which act to close the doors upon motor DM being energized for reverse rotative movement. Spring 31 acts through chain 4U directly on lever 32 to close the car door as reverse movement of motor DM takes place. Retiring cam 45 drops back as this reverse movement takes place which enables spring 65 to straighten out the toggle and thus close the hoistway door. Thus while the doors are spring closed, their closing movement can not take place any faster than permitted by motor DM. As the doors reach closed position, the door close limit switch opens to bring motor DM to a stop and the stopping of the doors is cushioned by their checks.

Referring now also to Figures 2 to 9 inclusive, the safety mechanism will be described. In elevator construction, vertical channels are pros vided at the leading edges of the car door and hoistway door to close the space between them. These channels are known as sight guards, the hoistway door sight guard being designated HSG and the car door sight guard being designated CSG. The car door sight guard is made up of a pair of angles and 8l which extend the full height of the door. Each angle is covered on its outer side with sheet insulating material 82, adhered thereto as by cementing. Angle 8i! is secured to the leading edge of the front door section 34 at vertically spaced intervals by screws 83, being insulated from the door by washers 84 of insulating material. Angle 8| is secured to angle 80 by screws 85 and 86 of insulating material such as nylon, screws 8S extendingr into straps 81 welded to angle 80 at vertically spaced intervals. The ends of the sight guard are closed by plates 88 welded to angle 80.l A plurality of antennae CA in the form of electrically conductive plates 90 are arranged along the front face of angle 8| to cover a space suiiicient to scan a person of average height, three antennae having been found satisfactory to cover a height of five feet. The edge 89 of each antenna is curved toward the hoistway door. The face and the adjacent front portion 92 of the side of the angle are cut away between straps 0"! over the scanning area to expose the antennae, as illustrated in Figures 3 and 6. Adjacent their ends the antennae are secured as by screws to mounting posts 80 of insulating material (see Figures 4 and 7). These posts are adjustably mounted in blocks S4 of insulating material secured to angle 80 by screws 8o. The posts ex tend into apertures in the blocks and are clamped in adjusted position by screws which extend across slots 01.

Arranged behind each antenna midway between the ends thereof is an electronic gas tube DPT, preferably a cold cathode gas tube. A tube having a wire anode such as the RCA 1C21 type but without the paint on the outside of the glass has been found satisfactory and has been illustrated. This tube has an annular shaped cathode |0|, a wire anode |02 which extends perpendicularly through the cathode to within a short distance of the top of the glass envelope |03, and a control electrode DPTE in the form of a wire loop. The tube is mounted in a socket |05 which is mounted on mounting posts |05 and secured thereto by screws |01. These posts are secured to the back of angle 80 as by welding. |0 are tabs for making electrical connections to the socket. An area CS on the outside of the tube envelope at the top is covered with an electrically conductive material, this conductive spot CS and electrode DPTE both acting as controls for the tube. Secured as by riveting to the back of the antenna in front of the tube is a stud ||2. A spiral spring ||3 connects the spot CS on top of the envelope to the stud ||2, being secured in a groove H4A formed on the stud. This provides an electrical connection from the antenna to the spot CS on the outside of the tube envelope adjacent the anode. A lock type tab ||5 is secured between the stud H2 and the antenna and is utilized to effect an electrical connection between the antenna and the control electrode of the tube, as shown in the wiring diagram. As will be explained later, the tube is fired by effecting an increase in antenna to ground capacity by the body capacity to ground of a person in the zone of influence of the antenna. The arrangement for each of tubes DPT is the same.

A face plate |20 commensurate with the scanning area along the front edge of the car door covers the cut away portions of the face 8| and side 92 of angle 8|. This plate is of opaque insulating material, opaque lucite of suitable color having been found satisfactory. An elongated trough |2| is formed along the back of plate |20 to receive the antennae. Spacer blocks |22 are provided in this trough at the straps 81 and the front |23 of the plate is secured to the straps at these points by the screws 86. Abutment bars |24 are provided for the plate between straps 81, these bars being Welded to angle 80. At the top and bottom, front |23 is similarly secured to angle 8| by insulating screws. At points aligned with straps 81 and at the top and bottom, the side |25 of plate |20 is secured to angle 8| by studs |26 of insulating material and spring retaining washers |21. Transparent inserts |28 are provided in the side |25 at the tubes DPT to observe Whether the tubes are functionlng.

To prevent unwanted ring of the tubes, they are shielded from ground by placing a potential on the sight guard. This also minimizes the capacity of antennae to ground, thus greatly enhancing the effect of body capacity to ground in firing the tubes. The connection to provide the sight guard potential is effected at one of the screws |01. To insure a good connection between angles 80 and 8|, a contact spring |32 mounted on the strap 81 above the antennae engages a cleaned off portion on the back of angle 8|. Also shields |33, connected to the sight guard, shield the screws 83 away from the tubes, the screws being connected to the car door and thus to ground. Insulation 82 minimizes any shock hazard from the potential placed on the sight guard, this insulation extending well around the corners and also around the abutment bars |24. Voltage divider resistors RVD, one for each tube, are mounted on the back of angle 80 and insulated therefrom by insulating washers and bushings, indicated generally at |36. Unwanted operation by persons in the car standing close to the closing door is prevented by having the antennae set back from the leading edge of the car door so that the ground potential of the portion of the car door to which the antennae are exposed has greater effect relative to such passengers than if the antennae eX- tended to or beyond the front edge of the door, and adjusting the voltage dividers RVD so that such unwanted operations are prevented.

The various connecting wires to the tubes, voltage dividers and sight guard are arranged in a shielded cable |4| fastened to a cable ccnnector |42 extending into the sight guard. This cable runs to a control and junction box |43 mounted on the car framework. Between the box and the sight guard, the cable is supported by the car door operating arm 32, being secured thereto by straps |44.

The above described arrangement not only prol tects against the closing car door but, owing to the provision of the curved edges 89 of the antennae exposed toward the hoistway door, extends the zone of influence to provide protection against the closing hoistway door as well. The hoistway door sight guard HSG is arranged to prevent unwanted firing of tubes DPT in a manner similar to the arrangement for the car door sight guard CSG. As shown in Figures 8 and 9, the hoistway door sight guard comprises a verti* cal angle and a larger vertical angle |5| welded together to form a channel. One leg |52 of angle |5| extends over the front edge of the leading section of the door. The angle assembly is covered with insulating material |53, adhered thereto as by cementing. The assembly is secured at vertically spaced intervals to the leading edge of the iront door section by screws |54. These screws extend through leg |55 of angle |50 and are insulated therefrom by washers |56 of insulating material. Angle |50 is cut away at I'5'I where plateEI for toggle lever 51 is secured to the door.

Prevention of unwanted firing of tubes DPT by the hoistway door is effected by providing a potential on the hoistway door sight guard HSG, thereby shielding the tubes from ground potential on the hoistway door. For this purpose a terminal stud IE@ is mounted in the front of the sight guard. A lock type tab ISI is secured by the terminal stud. A wire |52 is connected to the tab by means of which connection is made for placing the potential on the sight guard. The terminal stud is covered by the insulating material E53 and the connection of the wire to the tab is covered by insulating tape (not shown). A curved support |53 is provided near the top of the door for wire I62. From this point the wire extends downwardly `to a tensioning spring {efimounted on junction box I65 for the wire, this box being mounted on the sill ISG.

To prevent unwanted firing of the tubes as the doors near their strike jambs in closing, potential is provided on these jambs to shield the tubes from ground at these points. The arrangement for the car door strike jamb is illustrated in Figure 5. The car door strike jamb comprises the strike column il@ of the elevator cab on which is mounted a car post guard CPG. This post guard is of the saine construction as the hoistway door sight guard HSG, being made up of two vertical angles I'II and V12 welded together and secured to column I'E by screws ITS insulated from the post guard by insulating washers llt. The post guard is covered with insulating material V55 and has a terminal stud iS and tab Il'l for effecting the electrical'connection to place the shielding potential on the post guard. The terminal stud and connection are insulated as described for the hoistway door sight guard. The connecting wire ITS from terminal stud if@ is a shielded cable shown in Figure l and leads to the junction box 113.

The hoistway doei' strike jamb arrangement is illustrated in Figure 9. It comprises the strike janib column lf2-l to which vertical angle ISI is secured at vertically spaced intervals by screws E33 to form a post guard l-IPG. insulating material I8? covers angle ESI and screws IBS are insulated from the angle by insulating washers ce for effecting the electrical connection to place a shielding potential en the post guard.

e terminal stud and connection are insulated as described for the hoistway door sight guard. The connecting wire II from the terminal stud i235 leads to a junction box i873 mounted on the sill IE5.

Reference may now be had to Figure l which illustrates diagrammatically the various circuits for controlling the operation ef door motor DM. The circuits are shown in straight or acrossthe-line form, in which the coils and contacts of the various switches are separated in such marmer as to render the circuits as simple and direct as possible. The relationship of the coils and contacts may be seen from Figure 18s where the switches are arranged in alphabetical order and shown in spindle form. The coils and contacts in the wiring diagram are in horizontal alignment with the corresponding coils and contacts on the spindles. Inasmuch as the invention is applica-ble to various forms of elevator control systems, a complete elevator control system has not been shown. However, an application of the door control circuits to an elevator A terminal stud 185 and tab ISS are procontrol system is shown in the co-pending application of Glaser and Hornung, Serial No. 155,462, filed April 12, 1950, now Patent No. 2,589,242, dated March 18, 1952.

The electromagnetic switches employed in the circuits shown in Figure 10 are designated as follows:

DC-Door close switch.

DE--Door speed switch.

DO-Door open switch.

DP-Door protective relay. DPX-Auxiliary door protective relay. DR-Door control switch.

DT--Door time switch.

H-Field and brake switch.

NT-Hall time switch. KNT-Auxiliary hall time relay.

Throughout the description which follows, these letters will be applied to the coils of the above designated switches. Also, with reference numerals appended thereto, they will be applied to the contacts of these switches, as for example contacts DCI. The electromagnetic switches are illustrated in deenergized condition. Switch DR is a latching type switch and is illustrated in rese condition.

The door protection circuits are `connected to a source of single phase alternating current represented by iwires WI I and WI 2, wire W I2 being grounded at GR. SGT and DPDT are constant voltage transformers for providing the desired values of alternating current voltage for the protecti e circuits, volts R. M. S. having been found satisfactory in each case. Condensers QST and QDT are surge protecting `condensers for the primary windings of transformers SGT and DPDT respectively. Transformer SGT provides the potential for shielding tubes DPT from unwanted operation by the hoistway doors and the hoistway door strike jambs, both the hoistway door sight guards HSG and the hoistway doel' strike jamb post guards HPG being connected to the ungrounded side of the transformer secondary winding. The circuits are illustrated for convenience for a four floor installation, i. e., for four hoistway door sight guards HSG and their post guards HPG, the sight guards shielding aga-inst unwanted ring by the hoistway doors and the post guards against unwanted firing by the hoistway door strike jambs as previously eX- plained. Transformer DPDT provides the ypotential for shielding tubes DPT from unwanted operation by the car door itself and its strike jamb, both the car door sight guard CSG and the car door strike jamb post guard CPG being connected to the ungrounded side of the transformer secondary winding. Resistors RHPG, RHSG, RCP, RCSG are current limiting resistors, serving to minimize shock hazards in the event that the insulation on a sight guard or a post guard is pierced. The voltages applied to sight guards HSG and CSG and to post guards HPG and CPG are substantially in phase. Transformer DPDT and relays DP and DPX are in the control and junction box |43.

In accordance with the arrangement illustrated in Figure 4, the circuit-s for three door protective tubes DPT are illustrated. The door protective tubes are differentiated from each other by the appended numerals I, 2 and Similar diiferentiation is made as to the electrical apparatus associated with the respective tubes. Fixed resistors RVDA and RVDB for each tube supple- 9 ment voltage divider resistor RVD for that tube in controlling the voltage applied to the control electrode DPTE for that tube. An adjustable point on voltage divider resistor RVD for ea'ch tube is connected by way of current limiting resistor RIB to the control electrode of the tube, which in turn is yconnected to the conductive spot on the glass envelope of the tube adjacent the anode as previously explained. The antenna CA for ea-ch tube is connected to the control electrode DPTE and conductive spot CS on the envelope for that tube as previously explained.

Direct current derived from transformer DPDT by means of rectifier EDP is provided for the anode-cathode circuits of the tubes, approximately 150 volts being obtained with 120 R. M. S. Volts from the transformer secondary winding which is insufficient in itself to cause breakdown of the tubes. A filter network is provided by condensers QFI and QF2 and resistor RF. Resistors REDP, RDPX and RDPX2 are current limiting resistors. To prevent any undesirable effect on the tubes by action of stray iields on the conducting wires from the transformer to the tubes, voltage dividers, car sight guard and post guard, the wires leading from transformer DPDT to these elements and the return wire, are in the form of shielded conductors, indicated at I4I and |18 in Figure l, with the shields connected to ground as indicated at the points SGR in the wiring diagram. The coils of relays DP and DPX are supplied with current from transformer DPDT. Condenser QDPX is for timing the dropping out of relay DPX. EDDP is a rectier connected across the coil of relay DP to I.

time the dropping out of this relay.

The door operating circuits are illustrated as provided with direct current derived from alterhating current lines WII and WI2 by means of rectifier EDC. The door motor armature is designated DMA while its field winding is designated DMF. Resistors RDM are speed control resistors for door motor DM, resistors RDM3 and RDMl in series with the door motor armature serving for the door opening operation and resistors RDMI, RDM2 and RDM5 acting as a voltage divider to control the voltage applied to the door motor armature for the door closing operation. Resistor RDMF serves to control the strength of the door motor iield winding. EDB is a rectifier which serves to dynamically brake the door operating motor to bringl it to a stop upon operation of the protective mechanism. DOL, DCL, DEL are limit switches operated by the door motor. l5, Figure l, as previously indicated. DCB is a door close button. Resistor RXNT and condenser QXNT control the timing of relay XNT. Resistors RNTI and RNT2 and condenser QNT control the timing of switch NT. Resistor RDT and condenser QDT control the timing of switch DT. Resistor RDR is a current limiting resistor.

The manner in which the doors are controlled may vary considerably, depending upon the characteristics of the particular installation. In the particular circuits illustrated, the doors open automatically as a stop is made at a landing and close automatically upon the expiration of a given time interval. In order that this may be understood, assume that the car is in operation and is nearing a landing at which a stop is to be made. Relay XNT and switch NT are both operated during the'running of the oar, the circuit for the coil of relay XNT being through contacts H2 These are the limit switches in casing r and the circuit for the coil of switch NT being through contacts XNT2. As the car arrives at the landing at which the stop is being made, switch H drops out and in so doing engages contacts H3 and separates contacts H2. The separation of contacts H2 disconnects the coil of relay KNT from the supply lines. This relay does not drop out immediately, however, being delayed by the discharge of condenser QXNT. The engagement of contacts H3 completes a circuit by way oi contacts XNTI for the set coil of switch DR. This switch operates and latches itself in operated condition. As a result of the operation of switch DR, contacts DR2 engage completing a circuit by way of door open limit switch DOL for the coil of door open switch D0. This switch engages contacts D05 and D06 and separates contacts D04, establishing a circuit for the armature DMA for the door operating motor through resistors RDMS andl RDM4 for causing the operation ci the door operating mechanism to open the car door and also the hoistway door at the oor at which the stop is being made. Switch DO also separates interlock contacts D02 in the circuit for the coil of door close switch DC. As the doors move a certain distance from closed position, door speed limit switch DEL closes to complete a circuit for the coil of switch DE. This switch engages contacts DES to short circuit resistance RDMF in circuit with the door motor iield winding DMF' and engages contacts DE4 to short circuit resistance RDM4 in circuit with armature DMA of the door operating motor. This gives the desired control of the door operating motor for the particular door operating mechanism illustrated. As the doors near open position, limit switch DEL opens. However, the circuit for the coil of switch DE is maintained by way of contacts DOI and DEI. As the doors reach open position, door open limit switch DO-L opens, breaking the circuit for the coil of switch D0. This switch drops out to break the circuit for armature DMA of the door operating motor. It also breaks the circuit for the coil of switch DE which drops out, engaging contacts DES to establish a short circuit ior armature DMA to bring the door operating motor to a stop.

Upon the expiration of a given time interval, relay XNT drops out, separating contacts XNTI and XNTZ. The separation of contacts XNTI is without effect as switch DR is latched in operated condition. The separation of contacts XNT2 disconnects the coil of switch NT from the supply lines. This switch does not drop out immediately, being delayed by the discharge of condenser QNT. Upon dropping out, switch NT engages contacts NTI to establish a circuit by way of contacts DRI for the reset coil of switch DR which is restored to unlatched condition. Contacts NTI also complete a circuit by way of door close limit switch DCL and contacts DPE and D02 for the coil of door close switch DC to initiate the door closing operation. A time interval is thus provided, namely the interval of relay XNT, say three seconds, plus the interval of switch NT, say another three seconds, or a total of siX seconds, from the time that the stop is made before the closing of the doors is initiated. Switch DC upon operation engages contacts D02 and D04 and separates contacts D03 to cornplete a circuit for the armature DMA of the door operating motor for eiecting operation of the door operating mechanism to close the car door and hoistway door. During the closing operation, limit switch DEL is again closed completing a circuit for the coil of switch DE which short circuits motor eld resistance RDME1 and in addition separates contacts DES to remove a short circuit for a portion of resistor' RDME, giving the desired control of the door operating motor for the particular door operating mechanism illustrated. As the doors near closed position, switch DEL is opened but the circuit for the coil cf switch DE` is maintained by way of contacts DEZ and DCI. As the doors reach closed position, limit switch DCL opens, breaking the circuit for the coil or^ switch DC which separates contacts DC2 and DCI! to break the circuit for the door motor armature DMA and separates contacts DCI to break the circuit for the coil of switch DE. This switch drops out to reengage contacts DEB to establish a short circuit for armature DMA to bring the door operating motor to a stop.

If desired, as where a passenger is in the car and no further passenger' transfer is to be made, the passenger can by pressing door close button DCB shorten the time interval that the doors remain open. The pressing of this button establishes a shunt circuit for condenser QNT, thus substantially eliminating the time interval of switch NT or, in case switch NT is timing out, cutting its interval short. Thus, when relay KNT has dropped out, the pressing of button DCI-3 causes the immediate closing of the doors without waiting on the further time interval of switch NT.

Operation of the door protective mechanism will now be described. The protective circuits are eiiective only while the car is stopped to the provision of contacts HI. inasmuch as the same action takes place with respect to each tube DPT, the operation with respect to one of them will be described. Referring to the circuits for tube DPTI, with the arrangement illustrated, there is a capacity network from antenna CAi to shield CSG and from antenna CAI to ground. Thus a biasing voltage is applied to both the control electrode DPTEI and the conductive spot CSi adjacent the anode, which bias is due to a direct current potential taken from resistors RVDAi, RVDI and RVDBI, and an alternating current potential which is afunction ci the ratio of the two capacity networks. This is adjusted so that the biasing voltage is just below breakdown value. Resistor RIBI is of such value (s to eectively isolate the alternating current source from the direct current source. When a person enters or leaves the car his body capacity in effect increases the antenna to ground capacity and thus brings the potential of the conductive spot and control electrode to which it is connected nearer to ground potential. When during the closing of the doors antenna CAI comes within a certain distance of a person, the alternating current potential reaches a value which causes breakdown of tube DPTI, this being especially due to the action of this potential at the tube envelope adjacent the anode. This completes the anode-cathode circuit of the tubo which extends through the coil of door prete"- tive relay DP, causing this relay to operate. It is to be noted that the operation of relay DP may be effected by the proximity to any antenna of a person entering or leaving the car as the coil ci relay DP is connected in a circuit comrnon to the anode-cathode circuits of all the tubes DPT.

Upon operation, relay DP separates contacts BP2 to break the circuit for the coil of door close switch DC. Switch DC in dropping out breaks the circuit for armature DMA of the door operating motor as above described. In addition it engages contacts DC3 which completes a shunt circuit for armature DMA through breaking rectiiier EDB. This acts in eiect as a short circuit for armature DMA and brings the doors to a quick stop inasmuch as its action is instantaneous.

Relay DP, upon operation, also engages contacts DPS to complete a circuit for the coil of door open switch DO, causing the immediate reopening of the doors. It also engages contacts DPI to complete the circuit for the coil of auxiliary door protective relay DPX. This relay, upon operation, engages contacts DPX2 which complete a circuit for the set coil oi switch DR. It also engages contacts DPXI to by-pass the circuits for tubes DPT, causing the dropping out of relay DP. This relay is delayed slightly in dropping out by the discharge of its coil through rectiiier EDDP. This insures that the circuit for the coil of switch DO will be completed long enough for this switch to operate. Switch DO is maintained energized through contacts DB2 after contacts DP3 separate. When relay DP drops out it separates contacts DPI to break the circuit for the coil of relay DPX. This relay is delayed in dropping out by the discharge of condenser QDPX. This insures deionization of tubes DPT. Upon the operation of switch DO to initiate the door opening operation, contacts D03 engage to complete a circuit for the coil of switch NT, causing this switch to operate. This circuit is maintained through contacts D03 until the doors reach open position. Thus the time delay before the reclosing of the doors starts from the time they reach open position. This time interval is that due to switch NT alone and is thus shorter than the time interval provided when the doors are opened incident to stopping the car at a landing. In this connection, it is to be noted that in case of congestion when the passenger transfer cannot be eected quickly, so long as any person is in the Zone of influence of the antennae there will be repeated operations of relays DP and DPX until this condition ceases to exist. Thus the coil of switch NT is repeatedly energized by way of contacts DPX3 to maintain the doors in open position. Also the time delay in the dropping out of switch NT does not start until the congestion is cleared. The delayed dropping out of relay DPX insures the full charging of condenser QNT and thus the reestablishment of the full time interval of switch NT in the event that relay DPX is operated during the time interval of switch NT.

The system may be arranged so that if due to the protective mechanism the doors fail to close after a certain period, say iiiteen seconds, the door protective mechanism is rendered ineective and the doors are closed at a slow speed. Switch DT is utilized for this purpose. This switch is energized during running of the car, the circuit through its coil being completed by way of contacts H2 and H2. When a stop is made at a landing, these contacts separate to disconnect the coil of switch DT from the supply lines. This switch is delayed in dropping out for the prescribed period, say fifteen seconds, by the discharge of condenser QDT. Upon dropping out, switch DT separates contacts DTI to render the protective circuits ineffective and also engages contacts DTZ to reset switch DR and to complete a circuit by way of contacts DPZ for the coil of door close switch DC. Switch DT also engages contacts DT3 to short circuit a portion of resistance RDM2 across motor armature DMA so as to cause the door closing operation to take place at a slow speed so that if any one is hit he will not be injured. This arrangement obviates shutting down the car at a floor in the event of unwanted operation of the protective mechanism due, for example, to oversensitivity of one or more of tubes DPT. Circuits and apparatus for providing this operation are the subject matter of a divisional application, Serial No. 265,672, filed January 9, 1952, by William Henry Bruns and Samuel Davis, for Closure Operator Control Mechanism.

Protective mechanism in accordance with the invention has many advantages. It is silent in operation, there being no moving parts. It is highly sensitive and is instantaneous in operation, detecting the presence of a person or object considerably in advance of their being struck and thus enabling the doors to be brought to a stop and reversed with the minimum possibility of injury. t is reliable in operation and the possibility of unwanted operations is minimized. It is not aiTected by dirt or oil. It is not limited to a field in line with the door but with detecting mechanism on the car door alone its eld of inluence is extended to protect against the closing of both doors. The mechanism is not apparent to users of the car and presents a neat appearance. Also it is safe in operation as the possibility 1 of shock hazards has been minimized. Each detecting tube circuit is separately adjustable to take care of variations in tube characteristics.

When the invention is applied to center opening doors, each of the two leading door sections of the car door are arranged as above des-cribed for the leading section of a side opening car door, each leading section having its own set of tubes and associated apparatus. Also the sight guards on each ci the two leading sections of each center opening hoistway door are arranged the same as above described for side opening hoistway doors. Where center opening doors are provided, inasmuch as the door sections close upon each other, there are no strike jambs so that the post guards are not provided. The invention is also applicable to single speed doors as well as two speed doors and may be applied to installations with different types of door operators. Also where expense is not a factor, the door protective tubes and associated apparatus may be provided on the hoistway doors, either alone or in conjunction with the car doors.

While the invention has been described as applied to an elevator control system in which both the starting and stopping ci the elevator car are under the control or the passengers themselves, it is also applicable to other control systems, especially those in which the starting of the car is automatic and in which the doors are closed automatically incident to the starting operation. The invention may ii desired be applied to installations in which attendants are provided in the car. While the circuits are arranged to effect the reopening of the doors by the protective mechanisni, they may be arranged simply to bring the doors to a stop, as by eliminating the control of switch DO by the protective mechanism. The construction of the protective mechanism and the protective circuits themselves are subject to considerable variation and while a combined alternating current and direct current source has been provided for the tubes, namely transformer DPDT and rectifier EDP, separate sources may be provided. Also other forms of periodic Voltage may be employed and may also be provided for the anode-cathode circuits although unidirectional current is preferred for these circuits. The

connection of the alternating current source in the ring circuit may be made at other points in the anode-cathode circuits.

Thus, as many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

i.. In an elevator installation in which an entrance-way provides accessto the elevator car at a floor, in which a closure is provided for said entrance-way and in which power operating mechanism is provided for said closure; a gas tube carried by said closure, said tube having an anode and a cathode; means for applying across the anode-cathode circuit of said tube voltage oi a value above sustaining value but insufficient to cause breakdown of the tube; a control for said tube; means responsive to a person moving into the path of said closure for applying bctween said control'and a point in said anodecathode circuit a difference in potential of recurrent impulses sufiicient to cause breakdown of the tube; and means responsive to said breakdown of said tube to control the operation of said power operating mechanism to stop the closing ci said closure.

2. In an elevator installation in which an entrance-way provides access to the elevator car at a floor, in which a closure is provided for said entrance-way and in which power operating mechanism is provided for said closure; a gas tube carried by said closure at the leading part thereof, said tube having an anode and a cathode; means for applying across the anode-cathode circuit of said tube voltage of a value above sustaining voltage of the tube but insufiicient to cause breakdown of the tube; means for preventingl unwanted iring of said tube by ground potential; means responsive to a person moving into the path or said closure for applying to said tube a control potential with respect to ground of recurrent impulses or a value suiiicient to cause breakdown of the tube; and switching means responsive to said breakdown of said tube to prevent operation of said power operating mechanism to close said closure.

3. In an elevator installation in which an entrance-way provides access to the elevator car at a iloor, in which a door is provided for said entrance-way and in which power operating mechanism is provided for said door; an antenna mounted along the front edge of said door; a gas tube having an anode and a cathode, said tube also having a control connected to said antenna; means for applying across the anodecathode circuit of said tube voltage of a value above sustaining voltage of the tube but insuflicient to cause breakdown of the tube; means for creating an electrostatic shield for said tube to prevent unwanted ring thereof ;v means for applying to a point in said anode-cathode circuit and to said control potentials with respect to ground of recurrent impulses of suiiicient diiierence to cause breakdown of the tube upon a person moving into the path of said door; and switching means responsive to said breakdown of said tube to prevent operation of said power operating mechanism to close said door.

4. In an elevator installation in which the elevator car is provided with a door and in which power operating mechanism is provided for said door; an antenna mounted along the front edge of said door; a cold cathode gas tube having an anode and a cathode, said tube also having a control connected to said antenna; means for applying to the anode with respect to cathode of said tube direct current voltage of a value above sustaining voltage of the tube but insuicient to cause breakdown or the tube but sufficient to sustain the tube once it is broken down; a shield for said tube; means for applying alternating current potential with respect to ground to both the anode-cathode circuit of said tube and said shield, the application oi said potential to said shield causing said control to have an alternating current potential of a value with respect to ground determined by the ratio of the antenna to ground capacity to the shield to antenna capacity, said control potential being insuicient to cause breakdown of the tube but upon increase in antenna to ground capacity by a person moving into the path of said door being brought suiiiciently near ground potential to break down the tube; and switching means responsive to said breakdown of said tube to prevent operation of said power operating mechanism to close said door.

5. In an elevator installation in which the elevator car is provided with a door and in which power operating mechanism is provided for said door; an antenna mounted along the front edge of said door; a cold cathode gas tube having an anode and a cathode and also having an internal control and an external control connected together and to said antenna; means for applying to the anode with respect to cathode of said tube direct current voltage of a value above sustaining voltage of the tube but insufiicient to cause breakdown of the tube and to said controls with respect to cathode direct current voltage of a value insuiiicient to cause breakdown of the tube; a shield for said tube; means for applying alternating current potential with respect to ground to both said anode and said shield, said controls having applied to them a resultant potential the magnitude of which is governed by the magnitude of the applied dir et current voltage and a portion of the applied alternating current voltage as is determined by the ratio of the antenna to ground and shield to ground capacitances, said resultant potential being of insufficient magnitude under normal conditions to cause breakdown of the tube but being of sufiicient magnitude upon a person moving into the path of said door thereby increasing the antenna to ground capacitance to cause breakdown of the tube; and switching means responsive to said breakdown of said tube to prevent operation of said power operating mechanism to close said door.

6. In an elevator installation in which the elevator car is provided with a door and in which power operating mechanism is provided for said door; a plurality of cold cathode gas tubes having their anode-cathode circuits connected in parallel; a plurality of antennae, one for each tube, mounted along the front edge of said door to provide a zone of iniluence to sca-n an average height person in the path of said door, each tube having an internal control and an external control, both connected to its antenna; means for applying to the anode with respect to cathode for each tube direct current voltage of a value above sustaining voltage of the tube but insuicient to cause breakdown of that tube and to said controls with respect to cathode of that tube direct current voltage of a value insufiicient to cause breakdown of the tube; a shield for said tubes on said door; means for applying alternating current potential with respectv to ground to both said anodes and said shield, said controls of each tube due to said alternating current potential applied to said anode and said shield having superimposed on the direct current potential applied to such controls an alternating current potential of a value with respect to ground determined by the ratio of the antenna to groundcapacity to the shield to antenna capacity, said superimposed alternating current potential being insuiiicient to iire the tube but upon a person moving into the zone of iniiuence of said antenna to increase the antenna to ground capacity being brought suiciently near ground potential to fire the tube; and switching means responsive to the ring of any tube to prevent operation of said power 0perating mechanism to close said door.

7.211 an elevator installation in which the elevator car is provided with a door,v in which a hoistway door isv provided at a floor served by the car, and which power operating meehanism is provided for operating said doors when the car is stopped at said iioor; an antenna mounted along the iront edge of said car door to provide a zone of iniiuence in the path of doors; a gas tube having an anode and cathode; a control for said tube connected to said antenna; means for applying to the anode with respect to cathode of said tube direct current voltage of a value above sustaining voltage of the tube but insuilicient to cause breakdown of the tube; means responsive to a person moving into the path of said doors for applying between said control and a point in the anode-cathode circuit of said tube a difference in potential of recurrent impulses sufficient to break down the tube; and means responsive to said breakdown of said tube to stop the closing of said doors.

En an elevator installation in which the elevator car is provided with a door, in which a hoistway door is provided at a floor served by the car, and in which power operating mechanism is provided for operating said doors when the car is stopped at said floor; an antenna mounted along the front edge of said car door to provide a zone of iniiuence in the path of said doors; a gas tube having an anode and a cathode; a control for said tube connected to said antenna; means for applying to the anode with respect to cathode or" said tube direct current voltage of a value above sustaining voltage of the tube but insuicient to cause breakdown of the tube; means for shielding said tube .from ground; means for applying to a point in the anode-cathode circuit of said tube and to said control of said tube recurrent voltage impulses the instantaneous magnitudes of which with respect to ground are insufficient to cause seid tube to nre but which magnitudes become suilicient difference to do so when an obinterposed in the path of said doors; and switching means responsive to the firing of tube to prevent operation of said power operating mechanism to close said doors.

9. In an elevator installation in which the elevator car is provided with a door, in which a hoistway door is provided at a floor served by the car, and in which power operating mechanism is provided for operating said doors when the car is stopped at said floor; an antenna mounted along the iront edge of said car door to provide a zone of influence in the path of said doors; a gas tube having an anode and a cathode, said tube also having a control connected to said antenna; means for applying to the anode with respect to cathode of said tube direct current voltage of a value above sustaining voltage of the tube but insuflicient to cause breakdown of the tube; means for shielding said tube against unwanted firing; means for applying alternating current potentials with respect to ground to a point in the anode-cathode circuit of said tube and to said control to provide a difference in potential between said control and said point which is insuicient to fire the tube but which becomes sufficient to do so upon a person moving into the zone of iniuence of said antenna to increase the antenna to ground capacity; and switching means responsive to the firing of said tube to prevent operation of said power operating mechanism to close said doors.

l0. In an elevator installation in which the elevator car is provided with a door, in which a hoistway door is provided at a floor served by the car, and in which power operating mechanism is provided for operating said doors when the car is stopped at said floor; an antenna mounted along the front edge of said car door to provide a Zone of influence in the path of said doors; a cold cathode gas tube having an anode and a cathode and also having a control connected to said antenna; means for applying to the anode with respect to cathode of said tube direct current voltage of a value above sustaining voltage of the tube but insufficient to cause breakdown of the tube; a shield for said tube on said car door; a shield on each hoistway door; means for applying alternating current potential with respect to ground to a point in the anode-cathode circuit of said tube and to said shields, said potential applied to said shields preventing unwanted iiring of said tubes by ground potential of said doors and that applied to said car door shield in addition causing said control to have an alternating current potential with respect to ground of a value determined by the ratio of the antenna to ground capacity to the car door shield to antenna capacity which is insuiiicient to lire the tube but which upon a person moving into the zone of iniiuence of said antenna to increase the antenna to ground capacity is brought suiiciently near ground potential to fire the tube; and switching means responsive to the firing of said tube to prevent operation of said power operating mechanism to close said doors.

l1. In an elevator installation in which the elevator car is provided with a door, in which a hoistway door is provided at each floor served by the car, and in which power operating mechanism is provided for operating said car door and the hoistway door at the licor at which a stop is made; a plurality of cold cathode gas tubes having their anode-cathode circuits connected in parallel; a plurality of antennae, one for each tube, mounted along the front edge of said car door to provide a zone of influence to scan a person of average height in the path of said doors, each tube having an internal control and an external control, both connected to its antenna; means for applying to 18 the anode with respect to cathode for each tube direct current potential of a value above sustaining voltage of the tube but insufficient to cause breakdown of that tube and to said controls with respect to cathode of that tube direct current potential of a value insuiiicient to cause breakdown of the tube; a shield for said tubes on said car door; a shield on each hoistway door; means for applying alternating current potential with respect to ground to a point in the anode-cathode circuit of each tube and to said shields, said potential applied to said shields preventing unwanted iiring of said tubes by ground potential of said doors and that applied to said car door shield in addition superimposing on the direct current potential applied to said controls for each tube in alternating current potential of a value determined by the ratio of the antenna to ground capacity to the car door shield to antenna capacity, said superimposed alternating current potential being insuilicient to fire the tube but upon a person moving into the zone of influence of said antenna to increase the antenna to ground capacity being brought sufliciently near ground p0- tential to re the tube; and switching means responsive to the firing of any tube to prevent operation of said power operating mechanism to close said doors.

12. In an elevator installation in which the elevator car is provided with a door, in Which a hoistway door is provided at each door served by the car, and in which power operating mechanism is provided for operating said car door and the hoistway door at the floor at which a stop is made; a plurality of cold cathode gas tubes having their anode-cathode circuits connected in parallel; a plurality of antennae, one for each tube, mounted along the front edge of said car door to'provide a zone of iniluence to scan a person of average height in the path of said doors, said tubes being adjacent their respective antennae and each tube having an internal control electrode and a spot of electrically conductive material on the glass envelope of the tube adjacent the anode to form a control, both controls connected to the antenna for that tube; means for applying to the anode with respect to cathode for each tube direct current potential of a value above sustaining voltage of the tube but insui.- cient to cause breakdown of that tube; an isolating resistor for each tube; a voltage divider network for each tube; means for applying said direct current voltage across said voltage divider networks, each network having an adjustable point thereon connected through said isolating resistor for that tube to said controls for that tube to apply to said controls With respect to cathode of that tube direct current potential of a value insuiiicient to cause breakdown of the tube; a shield for said tubes on said car door; a shield on each hoistway door; means for applying alternating current potential with respect to ground to a point in the anode-cathode circuits of said tube and to said shields, said potential applied to said shields preventing unwanted firing of said tubes by ground potential of said doors and that applied to said car door shield in addition superimposing on the direct current potential applied to said controls for each tube an alternating current potential of a value determined by the ratio of the antenna to ground capacity to the car door shield to antenna capacity, said superimposed alternating current potential being insuiiicient to fire the tube but upon a person moving into the zone of influence of said antenna to increase the antenna to ground capacity being brought surficiently near ground potential to nre the tube; and switching means responsive to the ring of any tube to prevent operation of said power operating mechanism to initiate the closing of said doors or, if the doors are closing, to prevent further operation of said power operating mechanism to close said doors and thus bring the doors to a stop.

13. In an elevator installation in which the elevator car is provided with a door and in which power operating mechanism is provided for operating said door; an antenna mounted along the front edge of said door to provide a zone of inuence in the path of said door, a cold cathode gas tube having an anode and a cathode; a control for said tube connected to said antenna; a shield for said tube on said door; a source of alternating current having one side grounded; a rectier; circuits connecting the ungrounded side of said source to the cathode of said tube and to said shield and the grounded side of said source through said rectifier tol the anode of saidtube, thus applying to the anode with respect to cathode direct current potential, such direct currrent potential being of a value above sustaining voltage of the tube but insuflicient to cause breakdown o the tube, and thus also applying alternating current potential With respect to ground to a point in the anode-cathode circuit of said tube and to said shield, said alternating currentpotential applied toY said shield preventing unwanted firing of said tube by' ground potential of said door and in addition causing said control to have an alternating current potential of av value determined by the ratio of the antenna to ground capacity to the shield to antenna capacity, said control potential being insufficient to nre the tube but upon a person moving into the zone of influence of said antenna to increase the antenna to ground capacity being irought suiciently near ground potential to nre the tube; and switching means responsive to the firing of any tube to prevent operation of said power oper ting mechanism. to close said door.

1li. In an elevator installation in which the elevator. car is provided with a door and in which power operating mechanism is provided for operating. said door; an antenna mounted along the front edge of said door to provide a zone of inuence in the path oi said door, a cold cathode gas tube having an anode and a cathode, said tube alsoy having an internal control and an external, control, both connected to said antenna; a shield for said tube on said, door; a source of alternating current having one side grounded; a rectifier; circuits connecting the ungrounded side of said source to the cathode of said tube and to said shield and the grounded side of said source through said rectifier to` the anode of said tube, thus applying to the anode wit respect to. cathode direct current potential, such direct current potential being ofa value above sustaining voltage of the tube but insufficient to cause breakdown ci the tube, and thus also applying alternating current potential with rcspect to ground to a pointl in the anode-cathode circuit of said tube and to sai-d shield; an isolating resistor; a voltage divider network connected across the ungrounded side of said alternating current source and said rectiiier and having an adjustable point thereon connected through said isolating resistor to said controls to apply thereto a direct current potential below breakdown value, said alternating current-potential applied to said shield preventing unwanted firing of said tube by ground potential or" said door and in addition causing to be superimposed on the direct current potential applied te said controls an alternating current potential of a value determined by the ratio oi' the antenna to ground capacity to the shield to antenna capacity, said superimposed alternating current potential being insuiiicient to fire the tube but upon a person moving into the zone of influence of said antenna to increase the antenna to ground capacity being brought sufiiciently near ground potential to lire the tube; andr switching means respon ive to the firing or" any tube to prevent operation oi said power operating mechanism to close said door.

15. In an elevator installa-tien in which the elevator car is provided with a door and in which power operating mechanism is provid d for operating said door; a sight guard for said door electrically insulated therefrom; an antenna mounted in said sight guard to be exposed in the path of movement of said door, a cold cathode gas tube mounted in said sight guard and having an anode and a cathode; a control for said tube connected to said antenna; means for applying voltage to the anode-cathode circuit of said tube of a value above the sustaining voltage of the tube but insuiicient to break down the tube; means for applying alternating current potential with respect to ground to both the anodecathode circuit of said tube and to said sight guard, said alternating current potential applied to said sight guard causing said sight guard to shield said tube and antenna against unwanted ring of said tube by ground potential and in addition causing said control to have an alternating current potential of a value determined by the ratio of the antenna to ground capacity to the sight guard to antenna capacity, said control potential being insuiiicient to nre the tube but upon a person moving into the zone of influence of said antenna to increase the antenna to ground capacity being brought sunlciently near ground potential to fire the tube; and switching means responsive to the ring of any tubeto prevent operation o said power operating mechanism to close said door.

16. In an elevator installation in which the elevator car is provided with a door, in which a hoistway door is provided at each door served by the car, and in which power operating mechanism is provided for operating said doors; a sight guard for said car door electrically insulated therefrom; a plurality of cold cathode gas tubes mounted in said sight guard, said tubes having their anode-cathode circuits connected in parallel; a plurality of antennae, one for each tube, positioned in vertical alignment along the front edge of said sight guard to provide a zone of iniiuence extending horizontally across the path of said car door and vertically substantially from the floor of the car to scan a person of average height, each antenna being curved backwardly along its edge toward the hoistway door to extend horizontally said zone of influence across the path of said hoistway doors, said guard being cut away to electrically expose said antennae, each tube having a control connected to its antenna; meansl for applying direct current voltage to the anode-cathode circuits of said tubes of a value above the sustaining voltage of the tubes but insufficient to break down the tubes; means for applying alternating current potential with respect to ground to a point in the anode-cathode circuit of each tube and to said sight guard, said alternating current potential applied to said sight guard causing said sight guard to shield said tubes and antennae lagainst unwanted iiring of said tubes by ground potential on said car door and in addition causing each antenna to have an alternating current potential of a value determined by the ratio of the antenna to ground capacity to the sight guard to antenna capacity, said potential of each antenna being insuilicient to fire the tube for which the antenna is provided but upon a person moving into the zone of iniluence of such antenna to increase the antenna to ground capacity being brought suillciently near ground potential to iire such tube; switching means responsive to the firing of any tube to prevent operation of said power operating mechanism to close said doors; a sight guard for each hoistway door electrically insulated therefrom; and means for applying to said hoistway door sight guards alternating current potential with respect to ground in phase with the potential applied to said car door sight guard to prevent unwanted firing of any of said tubes by ground potential on said hoistway doors.

17. In an elevator installation in which the elevator car is provided with a door, in which a hoistway door is provided at each oor served by the car, and in which power operating mechanism is provided for operating said doors; a sight guard for said car door electrically insulated therefrom; a strike jamb for said car door having a post guard electrically insulated therefrom; a plurality of cold cathode gas tubes mounted in said sight guard, said tubes having their anodecathode circuits connected in parallel; a plurality of antennae, one for each tube, positioned in vertical alignment along the front edge of said sight guard to provide a zone of influence extending horizontally across the path of said car door and vertically substantially from the iioor of the car to scan a person of average height, each antenna being shaped to extend horizontally said zone of influence across the path of said hoistway doors, said guard being cut away to electrically expose said antennae, each tube having a control connected to its antenna; means for applying direct current voltage to the anodecathode circuits of said tubes of a value above the sustaining voltage of the tubes but insufficient to break down the tubes; means for applying alternating current potential with respect to ground to a point in the anode-cathode circuit of each tube, to said post guard and to said sight guard, said alternating current applied to said post guard shielding said tubes and antennae against unwanted ring of said tubes by ground potential on said strike jamb, said alternating current potential applied to said sight guard causing said sight guard to shield said tubes and antennae against unwanted firing of said tubes by ground potential on said car door and in addition causing each antenna to have an alternating current potential of a value determined by the ratio of the antenna to ground capacity to the sight guard to antenna capacity, said potential of each antenna being insuilicient to fire the tube for which the antenna is provided but upon a person moving into the zone of influence of such antenna to increase the antenna to ground capacity being brought suliciently near ground potential to lire such tube; switching means responsive to the firing of any tube to prevent operation of said power operating mechanism to close said doors; a sight guard for each hoistway door electrically insulated therefrom; a strike jamb for each hoistway door, each hoistway door strike jamb having a post guard electrically insulated therefrom; and means for applying to said hoistway door sight guards and post guards alternating current potential with respect to ground in phase with the potential applied to said car door sight guard to prevent unwanted firing of any of said tubes by ground potential on said hoistway doors or their strike jambs.

18. An elevator installation in which a closure is provided for controlling access to the elevator car, in which power mechanism including a direct current operating motor is provided for operating said closure, in which means is provided for connecting the armature of said motor to a source of direct current to cause operation of said mechanism to close said closure and for disconnecting said motor armature from said source to discontinue the closing operation of said closure by said power mechanism when a person moves into the path of said closure; characterized in that a rectifier is provided which is connected across said motor armature with a polarity to absorb the motor armature current and thus dynamically brake the motor and bring said closure to a stop upon disconnection of said motor armature from said source when a person moves into the path of said closure.

19. An elevator installation in which an entranceway is provided for the elevator car, in which a door is provided for said entrance-way, in which power mechanism including a direct current operating motor is provided for operating said door. in which switching means is provided for connecting the armature of said motor to a source of direct current to cause operation of said mechanism to close said door, and in which safety mechanism is provided for protecting a person moving into the path of said door when closing by causing operation of said switching means to disconnect said motor armature from said source, discontinuing the closing operation of said door by said power mechanism; characterized in that a rectifier is provided for connection across said motor armature, in that upon operation of said switching means. to effect the closing of said door said rectifier is disconnected from across said motor armature and in that upon operation of said switching means to disconnect said motor from said source in response to said operation of said safety mechanism said rectier is connected across said motor armature with a polarity to absorb the motor armature current and thus dynamically brake the motor and bring said door to a stop.

20. An elevator installation in which an entrance-way is provided for the elevator car, in which a door is provided for closing said entrance-way, in which power mechanism including a direct current operating motor is provided for operating said door, in which door open switching mechanism is provided for connecting the armature of said motor to a source of direct current to cause operation of said mechanism to open said door, in which door close switching mechanism is provided for connecting said motor armature to said source to cause operation of said mechanism to close said door, and in which safety mechanism is provided which is responsive to a person moving into the path of said door when closing to cause operation of said door close switching mechanism to disconnect said motor armature from said source, discontinuing the 23 closing operation of said door by said power mechanism, characterized in that a rectifier is provided which is connected across said motor armature when said door open switching mechanism is operating but with a polarity to block the iiow of current therethrough from said source, in that said rectifier is disconnected from across said motor armature upon operation of said door close switching mechanism to effect the closing of said door and in that said door close switching mechanism upon operation to disconneet said motor armature from said source in response to said operation of said safety mechanism connects said rectier across said motor armature with a polarity to absorb the motor armature current' and thus dynamically brake the motor and bring said door to a stop.

WILLIAM HENRY BRUNS. SAMUEL DAVIS.

No references cited.