US3367450A - Traffic supervisory apparatus - Google Patents

Description

Feb. 6, 1968 R. A. LESTER ETAL 3,36

TRAFFIC SUPERVISORY APPARATUS 5 Sheets-Sheet. 2

Original Filed July 50, 1964 FREQUENCY-KC mQ FDnFDO 20 O A NGLE- DEGREES FIG.6.

Feb. 6, 1968 R. A. LESTER ETAL 3,357,450

TRAFFIC SUPERVISORY APPARATUS Original Filed July 30, 1964 5 Sheets-Shem 5 I l I 65; RIOO l ow T CSOOLXIO'S l 3 RI3K K RIOK TA F|G.5A. 11% 67 Feb. 6, 1968 R. A. LESTER ETAL 3,367,450

TRAFFIC SUPERVISOBY APPARATUS Original Filed July '30, 1964 Sheetwlihem "l WRIOOK LC. T

AR ARA TSI I T52 v I I ARI T57: w PLA l AR2 ARAI 1968 R. A. LESTER ETAL 3,367,450

TRAFFIC SUPERVISORY APPARATUS Original Filed July 50, 1964 5 Sheets-Sheet 5 OUTPUT FIG.7.

lllrllllllll l VELOCITY-FEET PER SECOND SYSTEM OF PATENT 2,785,771 MODlFIED As SHOWN m HEAVY LINIES United States Patent 3,367,450 TRAFFIC SUPERVHSORY APPARATEE Robert A. Lester, Monroeville, and Arthur Nelikin, Pittsburgh, Pan, assignors to Westinghouse Electric Corporation, Pittsburgh, ha a corporation of Pennsylvania Continuation of application Ser. No. 386,321, July 30,

1964. This application 3, 1967, Ser. No. 620,555

14 Claims. (Cl. 187-52) ABSTRACT OF THE DISCLOSURE An elevator supervisory apparatus comprising an acoustic wave transmitter mounted on the elevator car which projects a diverging pattern of acoustic energy in front of the entranceway, and an acoustic wave detector also mounted on the car which is effective to delay closing of the doors in response to detection of acoustic waves reflected by prospective passengers in front of the elevator car. When the doors of the elevator car are closed the acoustic waves are reflected back into the car and the system is eifective for detecting the presence of passengers within the car for control purposes.

This application is a continuation of our prior application Ser. No. 386,321, filed on July 30, 1964.

. This invention relates to traflic supervisory apparatus and it has particular relation to apparatus for detecting the presence of load to be transported by a conveyor.

Conveyors may be arranged to travel in horizontal paths, vertical paths or paths inclined at an angle intermediate the horizontal and vertical directions for the purpose of moving load between spaced stations. The conveyor may stop at each of the stations for the purpose of receiving and discharging load. Although aspects of the invention are applicable to any of these forms of transportation the invention is particularly desirable for elevators and will be discussed below as applied to an elevator system.

In an elevator system an elevator car may be mounted for vertical movement relative to a plurality of spaced stations represented by the landings or floors of a building. The elevator car has an entrance through which passengers or other load may pass when the elevator car is stopped at a floor. Desirably, the elevator car may be provided with a door which is operable to open or close the entrance. In a typical automatic elevator system an elevator car may approach and stop at a floor at which load is to be discharged or received. The stopping of the elevator car is accompanied by opening of the car door to permit passage of load through the car entrance. Thereafter the door automatically closes and the elevator car departs from the floor.

In order to improve the operation of the elevator system certain information concerning actual or prospective load for the elevator car is desirable. Thus if a prospective passenger is approaching the elevator car information concerning his approach may be utilized to delay departure of the elevator car or to delay closure of the car door. If a passenger or other load is in the closing path of the door information concerning his presence desirably is employed for delaying closure of the door. If a passenger or other load is within the car information concerning his presence may be utilized to modify operation of the elevator system.

In accordance with the invention, radiant energy is projected for a substantial distance away from the elevator car towards a path traversed by load approaching the elevator car. Reflection of the radiant energy by prospective load is detected for the purpose of modifying the ice operation of the elevator system. In a preferred embodiment of the invention the reflection of the radiant energy is detected only for a moving load. The detecting apparatus desirably has major sensitivity in the direction usually taken by load approaching the elevator car. Preferably, the radiant energy is in the form of supersonic acoustic waves.

The invention further contemplates the combination of apparatus for detecting the approach of prospective load to the elevator car with apparatus for delaying departure of the elevator car or closure of the car door if an object is located in the closing path of the door. The invention additionally contemplates the provision of apparatus capable of detecting the presence of load within the elevator car.

It is, therefore, an object of the invention to provide an improved device for detecting loads adjacent a conveyor.

It is also an object of the invention to provide an improved device for anticipating approach of prospective load to a conveyor.

It is a still further object of the invention to provide an improved device for supervising a conveyor in dependence on movement and position of prospective load for the conveyor.

It is another object of the invention to provide an improved device for detecting the presence of a passenger external to an elevator car and the presence of a passenger within the elevator car.

It is a supplemental object of the invention to provide a conveyor car having a door and control means for controlling the door in dependence on the approach of load to the car and on the presence of load in the closing path of the door and having means for detecting the presence of load within the car.

It is still another object of the invention to provide improved apparatus wherein supersonic acoustic Waves are employed for detecting the presence or movement of load.

Other objects of the invention will be apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a simplified view in sectional elevation with parts broken away of an elevator system embodying the invention;

FIG. 2 is a view in front elevation of an elevator car suitable for the system of FIG. 1;

FIG. 3 is a view in perspective with parts broken away showing the elevator car of FIG. 1 adjacent a floor of a building;

FIG. 4 is a graphical representation showing sensitivity of a ceramic acoustic transducer suitable for the system of FIG. 1; I FIGS. 5A and 5B are separate parts of a diagrammatic representation showing circuits suitable for an acoustic transmitter and an acoustic receiver device suitable for the system of FIG. 1. FIG. 513 should be placed below FIG. 5A;

FIG. 6 is a graphical representation showing the frequency response of an acoustic transducer suitable for the system of FIG. 1;

FIG. 7 is a graphical representation showing overall bandpass characteristics of the circuits shown in FIGS. 5A and 5B;

FIG. 8 is a diagrammatic view showing circuits suitable for the system of FIG. 1;

FIG. 9 is a diagrammatic view showing a modified circuit arrangement which may be employed for the system of FIG. 1; and

FIG. 10 is a view in front elevation of an elevator car entrance showing a further modification of the invention.

Referring to the drawings, FIG. 1 shows a load transporter 1 in the form of an elevator car mounted in a hoistway for vertical movement with respect to a structure or building having a plurality of stations represented by landings or floors including the first to the fourth floors F1 to F4. The elevator car 1 is mounted on one end of a cable or rope 3 which extends around a traction sheave 5 to a counterweight 7. The elevator car 1 has an entrance E through Which passengers or other load may pass when the elevator car is stopped at a floor. The hoistway in which the elevator car 1 operates is provided with an entrance for each of the floors, such as those HEI to HE4 for the first to fourth floors, each of the hoistway entrances being aligned with the car entrance when the elevator car is stopped at the associated floor.

In order to detect the approach of a prospective passenger or other load to the elevator car 1 a sensory de-' vice S is provided which projects radiant energy capable of being reflected into the path traversed by the approaching passenger. For a long range the radiant energy may be directed parallel to the floor at which the elevator car is stopped over the path usually followed by an approaching passenger. However, it is presently preferred to direct the radiant energy towards that portion of the path which is adjacent the elevator car.

If desired, a sensory device may be mounted on the building adjacent each of the floors. For a tall multi-floor building the cost of the sensory devices required by such mounting and the cost of connecting and maintaining the sensory devices would be of seriously large proportions.

In a preferred embodiment of the invention a single sensory device S is mounted in the elevator car 1 adjacent the top of the entrance E and is oriented to direct its radiant energy downwardly and outwardl from the elevator car. By such mounting a single sensory device 8 suflices for all of the floors served by the elevator car.

It is a practice to provide the elevator car 1 with a door D which is operable to close and expose the entrance E. It is also a common practice to provide each of the hoistway entrances with a door such as the doors HD1 and HD4 for the first to fourth floors.

Let it be assumed that the elevator car 1 approaches and stops at the first floor at 1. The elevator car door D and the hoistway door HD1 automatically open to permit discharge or receipt of passengers by the elevator car 1. Subsequently, the doors D and HD1 reclose and the elevator car 1 leaves the first floor.

As the elevator car door D and the hoistway door HD1 open the sensory device S projects radiant energy in front of the elevator car 1. Should a prospective passenger approach the elevator car just after the doors start to close the sensory device S would detect the approach of the prospective passenger and would interrupt the closure of the doors and the starting of the elevator car 1 to permit the prospective passenger to board the elevator car.

After the elevator car door is closed the sensory device S may be employed for detecting the presence of a passenger or other load within the elevator car. If desired a sensory device may include separate mechanism for projecting radiant energy into the car and for detecting reflections produced by the passenger. In one embodiment of the invention the same mechanism is employed for projecting radiant energy through the open doors into the path of an approaching passenger and for projecting radiant energy into the elevator car to detect the presence of a passenger within the car. Under such circumstances, the radiant energy produced by the sensory device S may be reflected from the closed door D or may be otherwise directed into the elevator car 1.

Various door arrangements are suitable for the elevator car and for the hoistway doors. For example these doors may be side-opening, single-speed or two-speed doors. Alternatively, they may be center-opening, singlespeed or two-speed doors. For present purposes it will be assumed that single-speed center-opening doors are employed. The illustrated doors are mounted in vertical planes and are arranged for reciprocation in horizontal directions. A construction suitable for the elevator car 1 is shown in FIG. 2.

In FIG. 2 the center-opening, single-speed car door comprises two sections 9 and A9. The door is shown in its fully-open position. Insofar as is practicable a component for the door section A9 which is similar to a component for the first door section 9 will be identified by the same reference numeral employed for the corresponding component of the door section 5 prefixed by the letter A.

The door section 9 is provided with a door hanger 11 on which door-hanger wheels 13 are mounted for rotation. The door-hanger wheels for the door sections 9 and A9 are positioned for movement along a horizontallymounted track 15 secured to the front of the elevator car.

Movement of the door section 9 is effected by a lever 17 pivotally mounted on the elevator car by means of a pin 19. The lower end of the lever 17 is pivotally connected to one end of a link 21 the other end of the link being pivotally connected to the door section 9. The lever 17 is coupled to the lever A17 by a link 23 the ends of which are pivotally attached to the levers 17 and A17 by pivots 25 and A25, respectively. The pivot 25 is positioned above the pin 19 whereas the pivot A25 is located below the pin A19. Consequently, rotation of the lever 13 to close the door section 9 moves the link 23 in the proper direction to close the door section A9.

The lever 17 is operated by a suitable door operator 27 which includes a reversible-rotation electric motor 29 coupled through suitable gearing to a shaft 31. The shaft 31 carries an arm 33 which is pivotally connected to one end of a link 35 the remaining end of the link being pivotally connected to the lever 17. Consequently, the motor 29 may be energized in a conventional manner for the purpose of opening and closing the door sections 9 and A9.

Devices capable of detecting the presence of an object in the closing path of the door sections are associated with those edges of the door sections 9 and A9 which are the leading edges during a closing operation of the door. Devices of this type are well known in the art and may take the form of electric-field-producing edges which sense the capacitance of objects in the closing path of the door, or light beams which precede the door and which are interrupted by such objects. For present purposes it will be assumed that the door sections are provided with mechanical safety edges 41 and A41. The safety edge 4-1 is hung on the leading edge of the door section 9 by means of parallel links 43 and 45 each link having one end pivotally connected to the safety edge and one end pivotally connected to the door section. A stop 47 engages the link 45 to hold the safety edge 41 in an advanced position. During a closing operation of the door the safety edge 41 engages any object in the closing path. Continuing closing movement of the door section 9 forces the operating member of a normally-closed switch 49 mounted on the door section 9 against the safety edge 41 to open the switch. Such opening of the switch is employed for interrupting the closing movement of the door.

The door section 9 carries a coupling device CD for operating any hoistway door positioned adjacent the car door in a manner well understood in the art. The sensory device S is located adjacent the top of the entrance E for the purpose of projecting radiant energy through the entrance E towards a path usually followed by a passenger approaching the elevator car. This radiant energy may be of any type which may be reflected by the passengers or other load which the elevator car is intended to carry. Thus if the load is of an electroconductive type radiant energy may be in the form of high-frequency electromagnetic Waves comparable to those employed in radar.

In a preferred embodiment of the invention the radiant energy is in the form of supersonic acoustic waves. As a specific example the acoustic waves may have a frequency of the order of 40,000 cycles per second. It has been found that such waves are adequately reflected even by a reflecting surface such as woolen clothing. In order to produce such radiant energy a transducer ST is provided in the sensory device S. Many transducers capable of producing acoustic waves of the desired frequency are known in the art. Excellent results have been obtained from a transducer in the form of a barium titanate crystal having a diameter of 1 inch and a length of 1 inch. A similar transducer SR is employed for responding to reflected radiant energy.

The orientation of the two transducers ST and SR depends on the nature of the pattern desired. In the specific embodiment of FIG. 2 it will be assumed that these transducers are spaced by two inches in the direction of movement of the door sections.

As shown more clearly in FIG. 3 the acoustic axes of the transducers ST and SR are inclined about 25 relative to the vertical direction for the purpose of directing radiant energy from the transducer ST downwardly and outwardly to cover an area in front of the car entrance. Reflected radiant energy is transformed by the transducer SR into an electrical signal which may be amplified and applied to a suitable signal device or relay. If desired, the output derived from the transducer SR may be made insensitive to the magnitude of reflections obtained when no passenger or other load is before the elevator car. Any deviation in the magnitude of the reflected radiant energy then may operate the desired signal or relay.

In a preferred embodiment of the invention the frequency of the reflected radiant energy is compared with the frequency of the transmitted radiant energy. A difference between the frequencies of these quantities then produces a signal or operates a relay as desired.

When a passenger moves towards the elevator car components of this motion in the direction of the acoustic axes of the transducers produce reflected radiant energy having a frequency greater than the frequency of the transmitted radiant energy by an amount dependent on the rate of motion of the passenger. When the passenger moves away from the elevator car the frequency of the reflected radiant energy is less than the frequency of the transmitted radiant energy by an amount dependent on the motion of the passenger. This phenomenon is known as the Doppler effect. Thus if the output derived from the transducer SR is dependent on any deviation of the frequency of the reflected radiant energy from the frequency of the transmitted radiant energy the output indicates movement of a passenger either towards or from the elevator car. If such output is dependent solely on frequencies of the reflected radiant energy greater than the frequency of the transmitted radiant energy the output responds solely to movement of a passenger towards the elevator car. If the output is responsive solely to frequencies of the reflected radiant energy less than the frequency of the transmitted radiant energy the output responds solely to movement of a passenger away from the elevator car.

Portions of a passengers body moving towards or from the elevator car have substantial motion in the direction of the acoustic axes of the transducers. For example, a passengers shoes move upward and downward as the passenger walks to provide a strong output from the transducer SR. Similarly, a passengers hands swing in a path which has substantial components of motion in directions providing good signals for the transducer SR.

The sensitivity of the sensory device S is represented in FIG. 3 by arrows. Thus, at a point 53 which may be three feet in front of an elevator car at the floor level the sensory device S has substantial sensitivity to motion of a person towards the elevator car and to motion towards the sensory device S. A person moving toward the elevator car near this point can produce an adequate output from the transducer SR for delaying closure of the elevator door. However, it will be noted that at the point 53 the sensory device S has virtually no sensitivity to motion of a person in a horizontal direction parellel to the plane of the elevator door. This means that persons walking in the corridor parallel to the plane of the elevator door adjacent the point 53 will have little effect on the operation of the elevator system. This is highly desirable for the reason that the elevator car should be held only for prospective passengers desiring to enter such car.

At a point 55 at floor level in the plane of the elevator door the sensory device S responds to movement of an object in a direction towards the sensory device S, but is insensitive to motions of objects parallel to the plane of the door in horizontal directions. This is a desirable feature for the reason that movements. of the car door and the hoist way door will not operate the sensory device.

At an intermediate point 57 at floor level the sensory device S has adequate sensitivity to respond to motion of a person in any direction.

At a point 59 midway between floor level and sensory device S adequate sensitivity is shown for all directions of movement of the passenger with particularly high sensitivity for movements of a person in the direction of the acoustic axes of the transducers.

The sensitivity of a barium titanate transducer available on the market is shown in FIG. 4. This transducer is designed to operate at a frequency of 40,000 cycles per second and has a diameter of 1 inch and a length of 1 inch. In FIG. 4 abscissas represent angles in degrees of propagation or reception of sound waves measured from the acoustic axis of the transducer. Ordinates represent sensitivity of the transducer.

Systems for transmitting and detecting acoustic waves are well known in the art and a suitable prior art system may be employed here for similar purposes. However, in FIGS. 5A and 5B circuits are shown which have certain advantages and these circuits now will be considered. In FIG. 5A a transmitter 63 drives the transducer ST. In addition, a receiver 65 receives an input from the transducer SR. The output from the receiver 65 is supplied to an audio section 67 which is followed by a detector 73 (FIG. 5B) and a relay drive section '75. In the various circuits resistors are denoted by the reference character R followed by a numeral representing the value of the resistor in ohms (the letter K represents a conventional multiplying factor of 1000). Capacitors are designated by the reference character C followed by a numeral representing the value of the capacitance in microfarads. Transformers are represented by the reference T followed by a numeral representing the specific transformer. Transistors are designated by the reference character V followed by a numeral specific to each transistor. All transistors are shown as n-pn transistors. However, a p-n-p transistor may be employed in place of an n-p-n transistor by a circuit transformation known in the art. A semiconductor rectifier DE may be employed in the detector.

In the transmitter 63 the ceramic transducer ST is employed as a frequency-control element. The transducer, the capacitor C800 and the center-tapped transformer T0 form a bridge. This bridge has output terminals 63A and 63B together with input terminals 63C and 63D. The capacitor C800 is designed to balance the shunt capacitance of the transducer ST and its connecting cable.

The bridge of the transmitter is unbalanced only at the resonant frequency of the transducer ST. At this frequency the voltage available across the terminal 63A and 63B is applied across the resistor R240 for the purpose of driving the amplifier V1. The output of the amplifier is applied across the input terminals 63C and 63D to form a regenerative network which will oscillate at the resonant frequency of the transducer ST. The amplifier V1 is employed in a switching mode which has high efficiency. This circuit makes the transmitter substantially independent of temperature over a large range of variation thereof. An electroconductive shielding enclosure SH is provided for the transmitter 63.

The transducer SR may receive some leakage energy directly from the transducer ST. Alternatively, coupling loops L1 and L2 may be inductively connected respe tively to the windings of the transformers T and T1 for transmitting alternating current of the frequency of the transducer ST to the transformer T1, which desirably may be provided with a Faraday shield. Such leakage or coupled energy together with the reflected radiant energy received by the transducer SR are amplified in the receiver 65 which is provided with an electroconductive shielding enclosure SHl. It will be noted that the transistors V2 and V3 form a cascade amplifier. The difference between the transmitted and the reflected radiant energy is amplified by the audio section and the gain of the audio section may be adjusted by means of the adjustable tap TA on the gain resistor R10K.

The output of the audio section 67 is applied across the primary winding of a transformer T3.

In the detector section 73 the rectifier DE rectifies the output of the transformer T3. The rectified voltage provides drive voltage for the transistor amplifier V8.

The output of the amplifier V8 provides drive for a suitable transistor amplifier V9, V10 which in turn supplies operating current to control the pickup of a relay AR. The operating coil of the relay AR may have a rectifier connected thereacross to provide a discharge path for current produced by the magnetic field of the relay AR. The transistors V9 and V10 are shown in a Schmitt trigger configuration.

The relay AR has a set of contacts AR2 which controls the connection of a pilot lamp PL across a suitable source of alternating current. In addition, the relay operates contacts AR1 which may be used for a control operation in a manner discussed below.

The bandpass of the overall system is determined in part by the frequency response of the receiving transducer. The response of a suitable receiving transducer is shown in FIG. 6 wherein abscissas represent frequency in kilocycles per second and ordinates represent output values in decibels.

A suitable overall bandpass characteristic for the system is illustrated in FIG. 7. In this figure abscissas represent velocity in feet per second of a passenger. Positive values of the velocity represent the approach of the passenger towards the elevator car whereas negative values represent movement of the passenger away from the elevator car. Ordinates represent amplitude of the voltage supplied to the detector section 73.

Operation of the elevator car door may be controlled by circuits similar to those shown in FIG. 8. In this figure the motor 29 of FIG. 2 is represented by a field winding 29F and an armature 29A. The car-door safety-edge switches 49 and A49 of FIG. 2 are connected in series with the energizing coil of a door safety relay DR and with the contacts AR1 of the relay AR in FIG. B across direct-current busses L+ and L. The circuits of FIG.

8 are illustrated with the busses L+ and L in deenergized condition.

If the busses L-land L- are energized and if the switches 49 and A49 and the contacts AR1 are in closed condition the relay DR is energized and picked up to close its make contacts DRl, DR2 and DR3 and to open its break contacts DR4.

A switch SW6 is provided which may be operated to open or to close a door. Although this may be a manuallyoperated switch, in a preferred embodiment of the invention this switch represents the contacts of a relay or relays employed in any conventional door-operating systern to initiate an opening or a closing operation of the door.

Assuming that the door initially is in its fully-open condition, movement of the operating member of the switch SW6 up results in closure of its contacts SW6A to complete with a limit switch 87 and the contacts DR3 a circuit connecting a door-closing relay CL across the busses L+ and L for energization. The relay CL closes its make contacts CLl and CL2 to complete the following energizing circuit:

L+, DR2, CL2, 29F, CLl, DRl, 29A, L-

This circuit energizes the motor for operation in the door-closing direction. As the door nears its fully-closed condition, it opens the limit switch 87 to interrupt the energizing circuit for the door-closing relay CL. This relay thereupon drops out to terminate the energization of the motor 29.

It the door is to be opened, the operating member of the switch SW6 is operated down to close its contacts SW6B. These contacts, together with a limit switch 89, complete an energizing circuit for a door-opening relay OP. Consequently, the relay closes its make contacts CPI and 0P2 to complete the following circuit:

The motor now is energized in the proper direction to open the door. As the door nears its fully-open position, the limit switch 89 opens to de-energize the door-opening relay OP. This relay opens the make contacts 0P1 and 0P2 to deenergize the field winding 29F and the armature 29A.

Let it be assumed that during a door-closing operation a passenger approaches the elevator car and reflects radiant energy received from the transducer ST to the receiving transducer SH. It is assumed that this reflection is suflicient to cause pickup of the relay AR and opening of the contacts AR1 in FIG. 8. Opening of the contacts AR1 results in deenergization of the door-safety relay DR and this relay thereupon opens its make contacts DRl and DR2 to deenergize the field winding 29F and the motor armature 29A. Consequently, the door is brought to a stop. The contacts DR3 also open to interrupt the energizing circuit for the door-closing relay CL.

If desired the energization of the door-safety relay DR may also be accompanied by reopening of the doors. To

this end, break contacts DR4 are provided which are closed when the door-safety relay DR is deenergized to complete with the limit switch 89 an energizing circuit for the door-opening relay OP.

During a door-closing operation if a passenger is standing in the closing path of the door, one of the safety edges such as the safety edge 41 engages the passenger to open its associated switch 49. The opening of this switch results in deenergization of the door-safety relay DR to stop the closing movement of the door.

The overall operation of the system now may be considered. It will be assumed that the elevator car 1 approaches and stops at the first floor and that the car door and the hoistway door for the first floor both open. The transmitting transducer ST now transmits acoustic energy in the form of supersonic waves having a frequency of the order of 40,000 cycles per second towards a space in front of the elevator car. If no one approaches or leaves the elevator car the doors close in a conventional manner 50 permit movement of the elevator car away from the oor.

Let it be assumed that as the doors are closing a person approaches the elevator car and reflects some of the transmitted supersonic energy towards the transducer SR. The acoustic energy reflected from the person is shifted in frequency by an amount where AF is the frequency shift, f is the transmitted frequency, V is the component of the velocity of the person in the direction of the transducers, C is the speed of sound in air. As a specific example, if the person has a component of motion in the direction of the transducers of the order of one foot per second the frequency of the reflected acoustic energy would be greater than the frequency of the transmitted acoustic energy by approximately 73 cycles per second.

Acoustic energy of the transmitted frequency and acoustic energy of the reflected frequency are both converted into corersponding electrical signals which are amplified in the receiver 65. The audio section 67 forms in effect a bandpass filter which passes and amplifies the difference between the transmitted and received frequencies in this case 73 cycles per second.

The effect of raising the low-frequency cutoff of the system is to increase the minimum velocity of the approaching person to which the system will respond. By making the system insensitive to lower frequencies, the discrimination between people walking by the elevator and those entering the elevator may be improved since people entering the elevator have a higher component of velocity in the direction of the transducers The unit may also be made to discriminate between motion of a passenger towards the transducers and motion away from the transducers. This is accomplished by adjusting the center frequency of the receiving transducer SR to be slightly above or below the transmitted frequency. The frequency of the return from a person moving toward the transducers is slightly above the transmitted frequency and if the receiving transducer is most sensitive to these frequencies the system will be more easily triggered by this motion than by motion away from the transducers.

A very high gain receiving amplifier with sharp upper and lower cutoff frequencies will provide maximum range and most closely defined velocity limits. On the other hand, an amplifier with a bandpass which falls off at say a 6-decibel per octave rate as the frequencies depart the center of the passband will be sensitive at long range only to velocities corresponding to frequencies at the center of the bandpass. At closer ranges for the same target the unit will be sensitive to a larger range of velocities. An amplifier with this characteristic will sense people moving quickly toward the elevator at long ranges and will be capable of sensing slower velocities of such people only when the people are near the elevator doors.

The parameters of the transducers may be selected to suit the requirements of each application. For the applications above discussed a transducer having a beam angle of the order of 30 is satisfactory. The beam angle may be varied readily by suitable reflectors. For example, in FIG. 10 a transducer transmitter STA consists of a condenser microphone mounted in a five inch diameter parabolic reflector to produce a beam angle of the order of A similar transducer mounted in a parabolic reflector SRA is employed as a receiver. By inspection of FIG. it will be noted that the acoustic axes of the transducers STA and SRA are directed to intersect in front of the elevator car entrance. For such a configuration the major sensitivity occurs in the intersecting space of the transmitted beam and the sensitive cone of the receiver SRA.

A transmitter frequency of the order of 40,000 cycles per second has been found to be satisfactory. An increase in frequency would permit the adoption of transducers having materially smaller size. For example, a system working at 80,000 cycles per second would require transducers only half the size of the transducers employed in the 40,000-cycle-per-second system for the same directivity.

Systems, such as those represented in FIG. 3 and FIG. 10, may be combined in a similar installation. Thus, the first system may be given a broad field to which it is responsive for the purpose of detecting a moving person over a large portion of a hall in front of an elevator car. The second system may be highly directional to provide a response to a moving person only if the person is in a small predetermined area.

At high frequencies the attenuation of acoustic waves is substantial. For example, at 400,000 cycles per second acoustic waves have an attenuation of the order of 5 decibels per foot. At this frequency the sensitivity of the system would fall off at a rate of 10 decibels per foot. For this reason the system would have a. very high sensitivity for persons close to the transducers and would have a lesser sensitivity for persons more distant from the transducers.

Another method for determining the range of the system more precisely is to provide pulsing of the radiant energy from the transmitter and to gate the receiving transducer to receive reflections from the pulses. Such pulsing and gating is well known in devices for transmitting and receiving radiant energy such as radar systems. By following this practice, the sensitivity of this system may be restricted to specific ranges.

By suitable shaping of the transducer and its reflector the pattern of the radiant energy may be shaped in accordance with the requirements of each application. Although a round cross section may be provided for the beam transmit-ted by the transducer ST in FIG. 3 an elliptical cross section may be employed if so desired.

Although the system is relatively insensitive to motion of the doors preferably the system is turned off when the door sections are within a few inches of each other. To this end, a switch AS (FIG. 2) is closed when the door is open, but is operated to open condition when the door sections are within a few inches of each other by a cam ASC mounted on one of the door sections. The switch AS is employed for disabling the system in any desired manner. For example, in FIG. 5A, the switch. AS is employed for opening the output circuit of the receiving transducer SR.

A system similar to that here discussed may be employed for determining the presence of load within the elevator car. When so employed the transmitter transducer ST directs radiant energy into the elevator car. Reflections of the radiant energy are received by the receiver transducer SR. The system may be so adjusted that it is not responsive to the magnitude of the reflected radiant energy received from an empty car. However, any deviation in such magnitude of the reflected radiant energy caused by a person or persons in the car as determined by the receiver transducer SR results in pickup of the relay AR. Operation of the relay AR may be employed in any desired way as to illuminate a signal lamp or to modify operation of the elevator system. For present purposes it will be assumed that the system is adjusted to detect movements of persons within the elevator car in the same manner discussed with reference to movement of persons outside the elevator car.

In one embodiment of the invention the same system is employed for detecting objects outside the elevator car and objects inside the elevator car. This is accomplished {by constructing the cam ASC to clear the switch AS as the door sections reach fully-closed position. This restores the detecting system to operating condition. In addition, as the door sections approached closed position the cam ASC operates a throw-over switch TS having two sets of contacts T81 and T52. When the door is open the break contacts TSl (FIG. 5B) are closed to render the relay AR effective for controlling the elevator system in accordance with the presence or absence of a moving object in front of the elevator car. Under such conditions the contacts T82 are open. As the door reaches its fullyclosed condition the contacts TSl are opened to render the relay AR ineffective for control purposes. At the same time the contacts TSZ are closed to render the relay ARA effective for control purposes. When effective the relay ARA may be employed for operating a signal such as a 1 1 pilot lamp PLA or to control the operation of the elevator system in any desired way.

When the elevator door is closed radiant energy from the transducer ST is reflected into the elevator car. Reflections of this radiant energy are received by the receiver transducer SR and control the relay AR in accordance with the presence or absence of an object with-in the elevator car. In FIG. 9 an elevator system is disclosed which is identical to the system of Patent 2,785,771 except for the addition of the contacts ARI in series with the coil of the door-control relay 45. As long as the contacts ARI are closed the system of FIG. 9 operates precisely in the same manner as the system of the Patent 2,785,771. If a person approaches the elevator car for which the doorcontrol relay 45 is provided at the time the door is closing his approach results in pickup of the relay AR of FIG. 5B. The pickup of relay AR opens the contacts ARI of FIG. 9 to deenergize the door-control relay 45. Such deenergization results in reopening of the elevator car door in the manner discussed in the aforesaid Patent 2,785,771.

Although the invention has been described with reference to certain specific embodiments thereof numerous modifications falling within the spirit and scope of the invention are possible.

We claim as our invention:

1. In a load-transporting apparatus comprising a loadtransporter having a plane entrance permitting movement therethrough of load between a position within the loadtransporter and a position external to the load-transporter, a structure including a plurality of stations at which the load-transporter may stop for receiving or discharging load, motive means for moving said load-transporter between said stations, and control means for controlling the activation of the motive means, the improvement which comprises object-sensitive means mounted on said loadtransporter for detecting predetermined movement of objects external to said load-transporter, said objectsensitive means having a substantial first sensitivity to motion of an object from a position external to said loadtransporter in a first direction normal to and toward said plane entrance for operation from a first to a second condition, said object-sensitive means having a second sensitivity less than said first sensitivity to motion of said object adjacent and in a second direction parallel to said plane entrance, and modifying means responsive to operation of said object-sensitive means to said second condition for modifying said control means to delay at least temporarily activation of said motive means.

2. The apparatus of claim 1 in which said object-sensitive means comprises a radiant energy transmitter for producing radiant energy capable of reflection from loads to be transported, said radiant energy being directed outward in front of said entrance to encompass a path traversed by load approaching said entrance from any of said stations at which the transporter is located, and a radiant energy detector for detecting radiant energy reflected from objects moving within said path.

3. The apparatus of claim 2 in which the radiant energy comprises acoustic waves having a predetermined frequency and in which said detector is responsive to the difference in frequency between the transmitted and reflected wave.

4. An elevator system comprising the load-transporting apparatus of claim 3 wherein said structure comprises a plurality of vertically spaced floors, and a hatchway extending substantially vertically through said floors, said load-transporter comprising an elevator car in said hatchway mounted for vertical movement, the hatchway having doorways at selected floors to be served by said elevator car, said selected floors corresponding to the stations of claim 3, first door means for said doorways, and operating means for opening and closing said door means, said modifying means being effective to delay at least temporarily the closing of the door means by the operating means when the object-sensitive means is in said second condition.

5. The elevator system of claim 4 in which said acoustic wave transmitter is mounted on said car adjacent the top of the entrance and so oriented that it projects acoustic energy through said doorway downward and outward in front of said entrance in a diverging pattern, said pattern having a first cross section through said doorway which is small compared to the area of the doorway and having a second cross section which is substantially larger than said first cross section where said pattern strikes the floor in front of the entrance, said acoustic detector being mounted adjacent said transmitter and both being located on the car adjacent that portion of the doorways last obscured by said door means'during closure so that said door means is clear of the pattern ofsaid transmitted acoustic energy during a substantial part of the closing movement of the door means.

6. The elevator system of claim 5 in combination with second door means for the entrance of said elevator car, said operating means comprising means for opening and closing said second door means, said acoustic wave transmitter and detector being mounted inside said car adjacent the last portion of the entrance and doorway to be obscured by said door means during closure.

7. In a load-transporting apparatus comprising a structure having a plurality of landings between which load is to be transported, a load-transporter, means mounting said load-transporter for movement between said landings to transport load between the landings, said load-transporter having an entrance for permitting passage of load between the load-transporter and any of said landings at which the transporter is located, motive means for moving said transporter between landings, and control means for activating said motive means, the improvement which comprises a radiant-energy transmitter for producing radiant energy capable of reflection from loads to be transported between said landings, said transmitter being located on said transporter and oriented to direct radiant energy through said entrance in a diverging pattern having a cross section which increases with the distance thereof from the transmitter, said pattern encompassing a path traversed by load approaching said entrance from any of said landings at which the transporter is located, a radiant-energy detector located on said transporter for detecting radiant energy reflected by a load in said path, and modifying means responsive to detection of reflected radiant energy by said detector for inhibiting activation of the motive means by said control means.

8. The load-transporting apparatus of claim 7 in combination with door means operable for opening and closing the entrance of the transporter, and object-sensing means for detecting the presence of an object adjacent an edge of the door means which is the leading edge during closure of the door means, the modifying means being also responsive to detection of an object by the objectsensing means during closure of the door means for inhibiting activation of the motive means by the control means.

9. The load-transporting apparatus of claim 8 in which the radiant-energy detector will only detect radiant energy reflected from objects in motion within said pattern of transmitted energy.

10. An elevator system comprising the load-transporting apparatus of claim 7 in which the load-transporter is characterized as an elevator car, the landings are characterized as a plurality of vertically spaced floors, the radiant-energy detector is responsive only to radiant energy reflected by objects in motion within said pattern of transmitted energy and the structure includes a hatchway extending between said floors in which the elevator car is mounted for vertical movement, said structure also including doorways in said hatchway at selected floors to be served by said elevator car, first door means for said doorways and operating means for opening and closing said door means, said operating means being responsive to the operation of said modifying means so that doorclosure is delayed at least temporarily when said detector responds to said reflected radiant energ said radiant energy transmitter being mounted adjacent the top of the entrance of said elevator car and so oriented that said diverging pattern of radiant energy is projected downward and outward through the doorway at which the elevator car is located, said pattern having a first cross section through the doorway which is small compared to the area of the doorway and a second cross section where it intersects the associated landing which is larger by more than one order than said first cross section, said transmitter and detector being mounted on said elevator car adjacent the last portion of said doorway to be obscured by said door means during the closing movement thereof, so that said door means is clear of the pattern of transmitted acoustic energy during a substantial part of the closing movement of the door means.

11. The elevator system of claim 10 in combination with second door means for the entrance of the elevator car and in which said operating means comprising means for opening and closing said second door means, said second door means being so constructed that the last portion of the entrance to be obscured by the second door means is adjacent the last portion of the doorway to be obscured by the first door means during door closure, so that said door means are clear of the pattern of said transmitted acoustic energy during a substantial portion of the door closing movement.

12. The elevator system of claim 11 in combination with object-sensing means associated with one of said door means for detecting the presence of an object adjacent an edge of the door means which is the leading edge during closure of the door means, the modifying means also being responsive to detection of an object by the objectsensing means during closure of the door means for delaying, at least temporarily, closure of the door means.

13. In a load-transporting apparatus comprising a loadtransporter car having an entrance permitting movement therethrough of load between a position within the car and a position exterior to the car, and door means operable from a condition closing said entrance to a position opening said entrance, the improvement which comprises acoustic wave transmitting means for directing acoustic waves towards a path exterior to said car through which load approaches the car when the door means is open and for directing acoustic waves within the car when the door means is substantially closed, and acoustic detector means for detecting acoustic waves reflected from an object disposed in said path and for detecting acoustic waves reflected from an object disposed in said car.

14. An elevator system comprising the load-transporting apparatus of claim 13 in which the load-transporter car is characterized as an elevator car, said apparatus in combination with a structure comprising a plurality of vertically spaced landings between which load is to be transported, means mounting said elevator car for movement between said landings, control means for controlling the movement of said car, first modifying means connected to the acoustic detector for modifying said control means to a first operating condition. when the acoustic detector detects objects in said path and second modifying means connected to the acoustic detector for modifying said control means to a second operating condition when the acoustic detector detects objects within the car.

References Cited UNITED STATES PATENTS 1,887,209 11/1932 Lucas 18729 1,947,079 2/1934 Ellis 18752 1,981,884 11/1934 Taylor 340258 2,491,542 12/ 1 949 Woodyard 340258 2,629,865 2/1953 Barker 340258 2,660,718 11/1953 Summerhayes 340258 2,853,158 9/1958 Brandon 187-48 3,110,008 11/1963 Kendall 340--258 3,111,657 11/1963 Bagno 340258 FOREIGN PATENTS 656,399 8/1951 Great Britain.

954,536 4/1964 Great Britain.

119,507 10/1958 U.S.S.R.

EVON C. BLUNK, Primary Examiner.

H. C. HORNSBY, Examiner.

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