CA1241404A

CA1241404A - Detection means

Info

Publication number: CA1241404A
Application number: CA000395793A
Authority: CA
Inventors: John E. Gray
Original assignee: Otis Elevator Co
Current assignee: Otis Elevator Co
Priority date: 1981-02-10
Filing date: 1982-02-08
Publication date: 1988-08-30
Also published as: EP0070883A4; ES509497A0; EP0070883A1; JPH0423233B2; DE3277425D1; WO1982002787A1; EP0070883B1; ES8303601A1; JPS58500039A

Abstract

Detection Means Abstract In the entranceway between an elevator car and a floor are two oppositely sliding doors. The approach of these doors is controlled by a detection system that senses the presence of objects between the doors. This system includes, on each door, a plurality of emitters which are vertically spaced apart the door edge, for radiating noncollimated light towards the edge of the other door. At the top and bottom portions of each door edge there is a sensor which can receive the radiation from the emitters on the other door edge. The emitters on each door edge are sequentially turned on and the sensors on the opposite door edge provide a corres-ponding signal as they are turned on, unless an obstruction is in the way, causing the detection system to generate a signal that thus indicates that an object is between the doors.

Description

Description Detec~ion Means Technical Field This invention relates to equip~ent for sensing 5 that an object is in a defined space~ in particular, t ~ doorway, such as an elevator car doorway.

Background Art In ele~ators it is common to use one or more sliding doors and to open and close them automatically.
10 Consequently, often equipment is used that detects the presence of an obstructing body, namely a passenger, between the doors just prior to and during their ~ automatic closure to control equipment to prevent I ~he doors from closing more and, preferably, reopen ~ 15 them.
E One such device puts a light beam in a path transverse the door opening and uses a sensor to detect an interruption of ~he light beam, which would occur if an obstruction is be~ween khe door.
20 Then, upon sensing an interruption, the sensor issues a signal to the door control mechanism to alter the normal operation of the doors, preferably reopen them.
In usual practice that device has an array of . ~5 light sources dispo~ed on one side of the doorway, producing parallel light beams at different levels, and a corresponding array of photo-sensitive detectors arranged on the other door, for sensing those light ,~

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beams, thus creating a system which can sense obj~cts of different heights between the door. For maximum sensitivity, the light beams are generally colli-t mated by a lens to ensure that each sensor is responsive to one light sollrce.
This arrangement, although generally satis-i factory~has a disadvantage; because ~he light beams are ~paced apart from each other, objects between the beam s. are not sensed,. For instance, an arm extended horizontally may fail ~o be sensed.
The sensiti~ity could, of cour~e, be improved, S for instance, by spacing the parallel beams more closely together, in effect, providing substantially ~! contiguous light beams. But, that would be costly to implement, and, to maintain sensitivityl the t light beams would need to be highly collimated to pre~ent stray light from one sensor from reaching an adjacent - the wrong - sensor, as that could ¦ blind the sensor. The large number of photodetectors and their optical systems for beam collimation that would be needed would, o course, add significantl~
to cost. Mirrors may ~e used to extend the path length o~ a light beam from its source 50 that the beam tra~rses the door opening a number of times prior to striking a photodetector. But, while that ~ reduces the number o detectors r~quired, it also E reduces the intensity of the light beam reaching E each detector; thus, in the end, increasing the E demands on beam optics.
Consequently, the simple array of spaced apart parallel beams has ~een widely accepte~ as being the best compromise of safety, efficiency and cost.
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Disclosure of Invention Accordiny to the present invention, there is provided a method for detecting the presence of an object in the path of a sliding door, characterized by: transmitting energy diagonally ~etween various vertical points along the door perimeter to a detector as the door closes; sensing the output from a detector when an emitter diagonally opposed thereto is activated and providing a door stop signal when there is no output from the detector when the emitter is activated.
In a further aspect there is provided a detection system for detecting ~he presence of an object in the path of a sliding door, characterized by: a plurality of energy emitters located vertically on one of the two vertical perimeters defining the area in which the door-slides; an energy detector on the other perimeter at a position thereon that is diagonal to each emitter; means for activating the emitters in se~uence as the door slides and providing a signal when there is no output from the detector when an emitter is activated.
Brief Description of Drawings Fig. 1 is a schematic diagram showing an arrangement of emitters and sensors disposed, according to the invention, on ad~acent coopeirating ~levator doors.
Fiy. 2 shows the arranyement of Fig. 1 as the doors approach each other.

2~ Figs. 3, ~ and 5 show other arrangements of sensors and emitters according to the invention.

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Best Mode for Carrying Out the Invention In Figs. 1 and 2 there is a first elevator door 10 and a second elevatox door 20. These doors, , shown in an open position in Fig. 1, slide to open S and close, and, as hey close, the closure edge 11 of door 10 touches the closure-edge 21 of d~or 20.
A plurality of elements, made up of emitters 12 and 22 and sensors 13 and 23, define a first "array" and a second "array" on the closure edges 1~ 11, 2 1 .
The first array is comPrised of the emitters 12 ~ that are spaced apart from each other along the edge 11 and the sensors 13 that are at the top and ~ bottom of the edge 11.
The second array, sn the adjacent closure edge ~ 21 (on door 20~ is comprised of the remaining emitters 22 and sensors 23, which are on the edge 21.
The emitters may be light bulbs, LED devices ~ or any radiation emitting devi~e; for example, an ~ 20 infrared emittex that is modulated, so that its ~ emitted radiation is distinguishable from background _ radiation o~ the surxoundinys.
Likewise, the sensors may be any device that is ~ens~tive to the radiation o the emitters; yet, ...
adapted to be insensitive to radiation other than from the emitters. Thus, the sensors may be photo-.. diodes, phototransistors or the like, and these may - be gated in synchronization with a modulated emitter for improved sensitivity.
.. 30 The radiation from the emitters is not colli-., .
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.. lights and detectors in matched pairs, where :.
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collimation is required for good sensitivity. Conse-quently, each sensor actually receives radiation in a plurality of paths, each extending between the sensor and one of the emitters, as Fig. 1 shows~
In Figs. 1 and 2, the plurality of radiation paths that extend between emitters and sensors are shown; each path i5 distinguished there by an alphabetic index that is indicati~e of ~he sensor, and a numeral that is indicative of the emitter at the ends of ~he path. From Fig. 2 it is apparent - that these paths criss-cro~s, defining a network in space, the gap between the door closure edges - 11 and 21, and that the space between these paths - is smaller than in the prior art devices.
A circuit is provided whereby each emitter is energized to emit radiation in a first sequence; and each sensor is monitored in a second sequence so that - one emitter .is energized and one sensor is monitored, at any time. For example, each of the emitters 12 is energized in sequence while one of sensors 23 is monitored; then each of emitters 22 is energized sequentially while one of sensors 13 is monitored.
A~tex that~ each of emitters 12 are again sequentially energized while the other (the second of the ~ensors 23) is monitored. Then the emitters of sensors 22 are again sequentially energized while the other (the second sensor 13) is monitored. The exact sequence is not important, although, in a preferred, basic operation, each emitter and a sensor combina-tion that define a radiation path therebetween isrespectively energized and monitored repetitively many times per second in some sequence.

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Each path i5 thus monitored for obstruction once in an overall sequence, and, because the sensor does not receive radiation from other emitters and no other emitter is activated, the sensor is highly 5 sensitive to the obstruction. For maximum sensitivi~y, the sensitivity of the sensors may be adjusted in ~ synchronization with the enexgization of the emitters, since~each path involves a unique combination of ~ sensor and emitter. For example, the gain of an > 10 amplifier receiving a signal from sensor 13 may be ~ higher when one emitter 22 is activating path C7 than when another emitter 22 i5 activating path A6.
With reference to Fig. 2, it shows the emhodiment ~ of Fig. 1 r but when the doors are in a more nearly - 15 closed position, it will be seen there that the flux density in space of the radiation paths increases as ~ the doors approach each other.
~; In its simplest form, the invention includes embodiments such as those showm in Figs. 3, 4 and 5.
20 Yet, those skilled in the art will recognize that be-~ ~ause emitters are available at low cost in comparison with sensors, there are many possible geometric arrangement~ within the scope of the invention.
It is desirahle, to produce a signal, that only 25 one combination o~ sensor and emitter are active .. .
at any time; but, a combination of sensors and emitters - may also be selected for simultaneous activity. For ~ example, at the same time that an emitter on one edge and a sensor on the other edge are operative, ~ 30 a sensor on that one edge and an emitter on that other edge may be operative.

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The circuits required to construct embodiment~
according to the invention may use multiplex tech-niques which are apparent to those skilled in the . art from the foregoing. Also, embodiments of the - S invention may be utilized in a somewhat different application, not to monitor the dooxway entrance ~ to an elevator, but as a security device to monitor an area; for ex~mple, to sense when someone is in a - dangerous position with relation to a machine, or to sense the movement of people on and off properly, ..
- . or, for that matter, to sense the presence of an object in any predetermined space~
- Other modifications to the embodiment of the - invention that have been described will be obvious 15 to those skilled in the art, yet within the scope - of the invention.
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Claims

CLAIMS:

1. A Method for detecting the presence of an object in the path of a sliding door, characterized by:
transmitting energy diagonally between various vertical points along the door perimeter to a detector as the door closes;
sensing the output from a detector when an emitter diagonally opposed thereto is activated and providing a door stop signal when there is no output from the detector when the emitter is activated,

2. A detection system for detecting the presence of an object in the path of a sliding door, characterized by:
a plurality of energy emitters located vertically on one of the two vertical perimeters defining the area in which the door slides;
an energy detector on the other perimeter at a position thereon that is diagonal to each emitter;
means for activating the emitters in sequence as the door slides and providing a signal when there is no output from the detector when an emitter is activated.