GB2453804A - Sensing obstacles in front and to the front sides of sliding powered doors - Google Patents

Abstract

A method of detecting objects in front of a doorway, such as the powered sliding doors 1, 3 of an elevator car, comprising monitoring a first area, preferably directly in front 38 of the doorway, and separately monitoring at least one second area, preferably in front and to the side 34, 36 of the doorway. An obstruction signal may be produced fro the powered door controller if an object is detected in either area. Preferably the first area is monitored by arranging a transmitter 4 in one door and a receiver 5 in the opposite door to detect reflections form an obstacle. The second area may be served by having a transmitter and receiver arranged on the same door 4. (Figure 4 is a plan view, fig 5 is a front view).

Description

Doorway monitoring systems This invention relates to a method of and system for monitoring doorways and other openings. In particular (but not exclusively) it concerns methods and systems for detecting people or objects approaching lift (elevator) doors.

In a typical lift installation, a lift car travels in a hoistway between landings or floors and, at each floor, sliding lift doors and sliding landing doors open simultaneously to allow access to the lift. Usually, pairs of doors are slidably retracted apart (when open), or slidably moved together (when closed).

However, a single sliding door may close against a door post in both the lift car and the landing door opening. The following description will refer to pairs of sliding doors, but it will be understood that the same principles apply to single sliding doors.

As well known in the art, premature closure of the sliding doors can be prevented by the interception of a beam, such as an infrared light beam, which is transmitted across the lift door frame or opening and received by a corresponding receiver or detector which is connected to circuitry controlling a motor that causes door movement. When the obstruction is removed, there is usually a brief delay before the doors are allowed to close. In order to ensure operation at different heights above floor level (eg. to ensure detection of children, animals, or low objects), multi-beam curtains are used across the lift car doorway. These usually include an array of vertically spaced transmitters (eg. infrared transmitting diodes), which are arranged at one side of the lift door opening and which transmit beams to corresponding receivers (eg. infrared responsive diodes), :. which are arranged in a vertically spaced array at the other side of the lift door :..::: opening. The transmitter and receiver arrays are In the form of strips, which are * **.

mounted adjacent respective closing edges of the lift car door, whereby the *.*.

arrays move together with the respective doors and, when the doors are open.

provide a grid of horizontal beams extending across the lift door frame or : opening. If any beam is intercepted, the energy received by the detector is reduced, thereby triggering the circuitry which prevents door closure. (N.B. The term beam is used generally herein to denote any suitable form of energy, such as visible or infrared light, sound, or radio waves, and appropriate transmitters and receivers therefor).

These prior art systems detect only a person who has entered the space directly between the doors, and thus the doors may close prematurely against someone approaching the lift. Our earlier specification EP0699619A offers a partial solution to this problem by detecting persons approaching the lift generally orthogonally (or at least at a large angle) to the plane of the doors. The present invention offers a further improvement by detecting persons approaching the lift from the side, as for example happens when lifts are arranged in the side walls of a lift lobby set to one side of a corridor or reception area and extending orthogonally thereto.

According to one aspect of the Invention there is provided a method of detecting objects in front of a doorway or other opening comprising monitoring a first area in front of the opening, separately monitoring at least one second area in front of the opening and generating an obstruction signal if an object is detected in either area.

By In front of we mean forwardly out of the plane or other surface defined by the doorway or other opening, or an extension thereof. Thus an area to one side of the opening and forwardly out of its plane is for convenience said herein to be in front of the opening.

According to a second aspect of the invention, there is provided an obstruction detection system for detecting objects in front of a doorway or other opening, :. comprising a first monitoring means for monitoring a first area in front of the opening and at least one second monitoring means for monitoring at least one S.., second area in front of the opening, and means for generating an obstruction S...

indication if an obstruction is detected in either said area.

S

S... .5 * S The following features may also be provided within the aforesaid aspects of the :.: invention, either singly or in any feasible combination: -the first area is disposed centrally in front of the opening and the second area extends to the side of the opening; -the first area is monitored so as not to interfere with the monitoring of the at least one second area, and vice versa; -the first area is monitored by reference to energy having a first frequency characteristic and the at least one second area is modulated by reference to energy having a second frequency characteristic; -the first and second frequency characteristics are modulation frequencies; -the second monitoring means is insensitive to signals indicating an object in the first area, and vice versa; -the first monitoring means comprises a received sensitive to first monitoring means comprises a receiver sensitive to a signal having a first frequency characteristic, and the second monitoring means comprise a receiver sensitive to a signal having a second different frequency characteristic.

-the different frequency characteristics are modulation frequencies; -the first monitoring means comprises a transmitter for illuminating the first area with energy having at least the first frequency characteristic and the second monitoring means comprises a transmitter for illuminating the second area with energy having the second frequency characteristic; -a said receiver comprises filtering means to pass signals having one said frequency characteristic but not the other; -a said receiver comprises a synchronous detector gated at a said modulation frequency; and -a said transmitter and a second receiver of a said monitoring means are disposed on the same side of the opening.

Thus, with reference to this last feature, a third aspect of the invention provides an obstruction detection system for detecting objects in front of a doorway or other opening comprising at least one transmitter and at least one receiver configured to be disposed (preferably together) on or adjacent the same closing * vertical edge of a door or the corresponding edge of a door frame, the transmitter :*** being adapted to direct a beam of energy obliquely forward from the said edge to illuminate an object approaching the opening from the side, the receiver being adapted to receive said energy reflected from the approaching object.

*... a S * The invention also provides a lift or other structure comprising a system as set forth above.

The invention will now be described merely by way of example with reference to the accompanying drawings, wherein: Figure 1 is a plain view of a known lift installation; Figure 2 is an elevation showing the positions of transmitters and receivers, in figure 1; Figure 3 is a block circuit diagram of the installation of figure 1; Figure 4 is a plan view of a lift installation according to the present invention; Figure 5 is an elevational view of the installation of figure 4; Figure 6 is an elevation showing the positions of further transmitters and receivers according to the invention; and Figure 7 is a block circuit diagram of the installation of figures 4 and 5.

The following description relating to figures 1 to 3 is based on our earlier specification EP089961 9A, the full disclosure of which is incorporated herein by reference.

Refemng to the figures 1 and 2, a lift car (not shown) has lift car doors which are ***s* spaced by clearance gap 2 from landing doors 3. The gap 2 approximately S...

represents the hoistway in which the lift travels, although the running clearance is *.* normally less than that indicated by the drawing.

S S....

S S

Mounted adjacent the closing edge of each lift door 1 are respective strips 4 and S 5. Each strip is of channel (C-shape) cross-section and contains an array of S....

vertically spaced transmitters or receivers. Only one of each is shown in the cross-section. Strip 4 contains transmitters 6, such as infrared light transmitting diodes. Each of these transmits a thin narrow beam 7 to a corresponding beam receiver 8, such as an infrared sensitive photodiode. Beam 7 is one of a plurality of beams extending horizontally across the lift car door opening, thereby providing a multi-beam curtain. Circuitry (not shown) connected to receivers 8 is triggered by interception of beams 7 as a passenger enters the lift. This prevents door closure as explained above.

Forward-looking transmitters 9 and receivers 10, which may be similar infrared diodes, are located in the respective strips 4 and 5. The transmitters 9 transmit respective beams of (eg.) infrared radiation, but these beams are not directly received by the receivers since they are not located on the optical paths of the transmitters 9. Beam 11 is radiated at an angle (eg. about 45°) from the primary beam axis 7 towards a zone in front of the landing doors 3. In the absence of any object, such as passenger 12, no reflection of the forward-looking beams is received by auxiliary receivers lOa, lOb, lOc. However, when a passenger 12 enters detection zone 13, which is represented by overlapping fields of view of transmItter 9 and receiver 10, (receiver 10 being similarly angled eg. at about 45° to the primary beam axis 7) beam 11 will fall on the passenger's body and reflected radiation 14 will be received by one or more of the receivers lOa, lOb, lOc. Consequently, even though passenger 12 has not yet intercepted primary beams 7, the receivers 10 will operate to trigger the circuitry to prevent door closure.

The transmitters 9 and receivers 10 are preferably staggered as shown in figure 2, by arranging them at different heights above floor level. As shown in the drawing, receiver 1 Oa is located mid-way between transmitters 9a, 9b (and so on) :. as shown in figure 2. The staggered relationship helps to prevent any spurious S *.* response by beam receivers lOa-lOc, otherwise due to receiving directly any **I.

forwardly-directed beam radiation. However, this does not prevent the receivers lOa-lOc from receiving radiation reflected from an object, because this radiation is reflected at different angles (ie. scattered by a passenger's body, or other object) and some will enter one or more of the beam receivers lOa-lOc. p.. *

* Masks or shields 15 are located adjacent each of the transmitters and receivers 9, 10 so as to shield them from the curtain beam radiation. The receivers 10 are also angled away from the path 7 of the curtain beam and, in view of this, and the use of shields, the receivers 10 are arranged so as not to receiver any direct curtain beam radiation.

The principle described above, ie. of using forward-looking beam as wefi as curtain beam radiation may be used with circuitry of various types. One suitable circuit is shown schematically in figure 3. In practice, many of the functions shown as discrete blocks can be performed by appropriate software running on a micro controller at the core of the control circuit.

In operation, beam multiplexer 16 is used as a "master clock" of the system and it determines which detection function is operating and which beam or radiation pattern is selected. For example, in curtain beam mode, a group of transmitting diodes 6 are turned on and the equivalent group of receiving diodes 8 are activated so as to receive curtain radiation and to develop a trigger signal if the beam is intercepted. There may be, for example, five groups each having eight diode transmitting and receiver pairs, each group being consecutively switched on, in turn, so as to scan through a total of 40 primary beam diode pairs. After scanning the five groups of curtain beam diode pairs, the forward-looking transmitters and receivers are scanned. In this case, all of the forward-looking transmitters 9 and receiverslO are switched on, because it is not necessary to scan the forward-looking diode pairs separately (or in groups). There may be, for example, three diode pairs in the forward-looking beam system. Thus a cycle may be completed in which five groups of curtain diodes and one group of forward-looking diodes is scanned or monitored, before the cycle is repeated.

Different scanning patterns can be used in accordance with requirements. e.

**** When multiplexer 16 selects the direct or curtain beam pattern, the output of the * s.. selected groups of transmitting diodes modulated with (eg.) a square wave of approximately 15 Khz, and the corresponding receiving diodes 8 are monitored * by connecting the beam to receiving amplifier 17. The output of amplifier 17 is fed to a synchronous detector 20, via a gain control circuit 18, where the signal is rectified and converted into a D.C. voltage, which is proportional to the received signal strength. During a scan cycle, when the groups of curtain beam diode receivers are sequentially monitored, a signal level monitor 18 accumulates an average' received signal level. If this average value is more or less than a present threshold, it is used to change the gain control 18 to bring the average into the acceptable window" of voltage. Any beams which still fall outside this window (on the low end) are regarded as "blocked' A direct beam loss' detector 20 generates an obstruction detected" signal to tell a relay driver 21 to switch the door monitor output to "TC)P" or REVERSE" thereby preventing door closure.

When the muftiplexer 16 selects the forward-looking or reflected beam system, signal level monitor 19 then remembers' the gain set when the curtain beams were used and thereby provide some indication of the (closing) door aperture width. This remembered' gain is used as a reference for monitor 19 to preset the gain control 18 to suit known characteristics of the reflective system and thereby avoid having too much or too little gain for successfully detecting obstruction 12 within the reflective beam convergence zone 17. This feedback of information from the curtain beam system therefore enables successful operation of the forward-looking system in the preferred embodiment of the invention. In other words, the signal from the curtain beam system is used so as to reduce the gain or sensitivity of the forward-looking beam detecting system so that door closure Is not accidentally prevented by the receipt of radiation other than that reflected or scattered by the object in the convergent zone 13.

If a reflective obstruction is present in zone 13. then the reflected signal which is processed by amplifier 17, gain control 18 and synchronous detector 24, will exceed a preset tngger threshold and a reflected beam increase detector 22 will respond by activating relay driver 21 to prevent door closure. As a person could be in the convergence zone 13 but not be wanting to enter the lift car, a S...

time our function device 23 can be actuated after a short delay, to allow the doors to dose normally. Alternatively, breaking of the direct beam pattern 7 can be used as a signal that passengers are entering or leaving the car, so that * triggers from the reflective detector (which uses beams 12, 14) can be acted upon, or ignored, as appropriate. For example, if a passenger leaves the car, the *..: direct beams are broken first and the next reflected detection ignored (due to the passenger leaving the lift car). In another circumstance, a trigger from the reflective detector which is not followed within two seconds (for example) by a trigger from the direct detector can be ignored as spurious and the reflective system briefly disabled to prevent a delay in the car movement. In short, the reflective system (12, 14) is only necessary during the early part of door closure, because It would not be possible for a passenger to enter the lift car, once the doors have closed by a certain amount. Therefore, the forward-looking beam system can, in effect, be switched off, or desensitised, after the doors have closed by a certain amount (eg. half closed) to prevent the forward-looking beam detectors (10) from responding to spurious radiation (since the level of radiation will increase as the doors close), thereby unnecessarily preventing door closure.

Referring to figures 4, 5 and 6 in the present invention there are provided further transmitters which project additional relatively narrow-angie forward-looking beams 30, 32 into areas 34, 36 not covered (or not fully covered) by either the curtain beam 7 or the directly forward-looking beams 11. It can be seen for example in fIgure 4 that the forward-looking beams 11 illuminate only passengers centrally in front of the lift in a relatively restricted area 38. The beams 30, 32 however illuminate passengers approaching the lift from the side, and who have not yet reached area 38, and enable the doors to be held against premature closure.

The beams 30, 32 in this embodiment are of relatively restricted vertically extent, as can be seen from figure 5, and are provided by two pairs of infra-red transmitters 40, 42 (figure 6) on the closing edge of each car door 1.

Conveniently, these transmitters are interleaved with the transmitters 9, 10 in the channel section 5. Receivers 44, 46 are positioned adjacent each transmitter 40, 42 in the channel section, and are screened from them.

The arrangement differs from that of figure 1 in that each receiver 44, 46 receives radiation transmitted by its adjacent transmitter 40, 42 on the same side of the Is door, and reflected from an approaching passenger or other object.

a. 0...

Referring to figure 7, each transmitter 40, 42 consists of a 940nM infrared LED, the output of which is collimated by a lens 50 to provide a narrow directional beam. The two transmitters of each pair are driven in series from a DC supply via a transistor switch 54 gated by a nominally square-wave signal from a 455KHz oscillator 56 clocked by a ceramic resonator 58. The output of the LED thus is modulated at 455KHz. The frequency of 455KHz is chosen in this example merely because the components to provide it are readily available. It is important however that the modulation frequency of the transmitters 40, 42 is not a harmonic of the modulation frequency of the transmitters 9.

Assuming a would-be passenger 60 enters the area 34 or 36, the beams from the respective diodes 40 or 42 are reflected back to the receiver 44 or 46 adjacent that diode or its neighbour. The receivers 44, 46 are conveniently PIN diodes, the diodes in each pair being connected in parallel with each other in order to maximise the signal available. The output of the diodes is passed though a narrow pass-band 455KHz filter 62 to reject any signal from a transmitter 9 reflected from another passenger in the area 38, and also to reject the majority of interference from other sources eg. local lighting. The filtered signal is amplified by amplifier 64 and passed to a precision rectifier 66, in which the threshold voltage of the rectifier diodes effectively is eliminated, thereby increasing the signal-to-noise ratio and allowing smaller reflected signals to be detected.

The output of the rectifier is fed to a comparator 68 where it is compared with a DC reference voltage and the result of the comparison supplied to a microprocessor system controller 70. The controller 70 of course common to the system of figure 3, and includes at least the functions separately shown at 21 through 24 in that figure. A reflected signal above a predetermined value from comparator 68 results in the system controller 70 commanding the doors to remain open, for example by causing the direct beam loss detector 20 of figure 3 to send an detected signal to the relay driver 21.

*:::: It will be appreciated that the beams 30, 32 alternatively can be transmitted and detected by a system similar to that of figure 3, using synchronous detectors gated at different frequencies which are not harmonics of each other. Conversely the beams 7 and/or 11, 14 instead can be modulated and filtered at relatively high but different frequencies as in figure 7.

In a further variation, the forward-looking beams 11 and their associated transmitters and detectors may be omitted. Then instead the transmitters 40, 42 are extended in an array to cover the fuH height of the doorway, and are configured to produce a horizontally much more divergent beam. Then one beam from each side of the doorway together can cover the full area of interest, both directly in front of the doorway and the areas forward of but to the side of the doorway. In this embodiment, the two sets of transmitters and receivers operate at different unrelated frequencies that can be discriminated by filtering.

In a yet further variation, for use for example to control operation of a powered rotating door or the entrance to an escalator (moving stairway) a single broad-beam transmitter or array of transmitters is modulated at two discrete frequencies and illuminates the entire area of interest. Two sets of receivers monitor respective areas of interest in the overall area, but do not interfere with each other because they are tuned (filtered) to respective ones of the modulation frequencies.

Each feature disclosed in this specification (which term includes the claims) and/or shown in the drawings may be incorporated in the invention independently of other disclosed and/or illustrated features. In particular but without limitation the features of any of the claims dependent from a particular independent claim may be introduced into that independent claim in any combination.

Statements in this specification of the objects of the invention" relate to preferred embodiments of the invention, but not necessarily to all embodiments of the invention falling within the claims. Reference numerals appearing in the daims :**: are illustrative only and the claims shall be interpreted as if they are not present The text of the abstract filed herewith is repeated here as part of the specification. S.S*

* A method of detecting objects in front of a doorway or other opening comprising monitoring a first area in front of the opening, separately monitoring at least one second area in front of the opening and generating an obstruction signal if an object is detected in either area. I0

Claims (16)

1. Claims 1. A method of detecting objects in front of (as herein defined) a doorway or other opening comprising monitoring a first area in front of the opening, separately monitoring at least one second area in front of the opening and generating an obstruction signal if an object is detected in either area.
2. 2. A method according to claim 1, wherein the first area is disposed centrally in front of the opening and the second area extends to the side of the opening.
3. 3. A method according to claim 1 or claim 2, wherein the first area is monitored so as not to interfere with the monitoring of the at least one second area, and vice versa.
4. 4. A method according to claim 3, wherein the first area is monitored by reference to energy having a first frequency characteristic and the at least one second area is modulated by reference to energy having a second frequency characteristic.
5. 5. A method according to claim 4, wherein the first and second frequency characteristics are modulation frequencies.
6. 6. An obstruction detection system for detecting objects in front of (as S...

   herein defined) of a doorway or other opening comprising a first monitoring means for monitoring a first area in front of the opening and * at least one second monitoring means for monitoring at least one *.** * second area in front of the opening, and means for generating an :

   obstruction indication if an obstruction is detected in either said area. S.. S *</p>..CLME: <p>
7. 7. A system according to claim 6, wherein the second monitoring means is insensitive to signals indicating an object in the first area, and vice versa.
8. 8. A system according to claim 6 or claim 7, wherein the first monitoring means comprises a receiver sensitive to a signal having a first frequency characteristic, and the second monitoring means comprise a receiver sensitive to a signal having a second different frequency characteristic.
9. 9. A system according to claim 8, wherein the different frequency characteristics are modulation frequencies.
10. 10. A system according to claim 8 or claim 9, wherein the first monitoring means comprises a transmitter for illuminating the first area with energy having the first frequency characteristic and the second monitoring means comprises a transmitter for illuminating the second area with energy having the second frequency characteristic.
11. 11. A system according to claim 8, 9 or 10, wherein a said receiver comprises filtering means to pass signals having one said frequency characteristic but not the other.
12. 12. A system according to any of claims 8 to 11, wherein a said receiver comprises a synchronous detector gated at a said modulation frequency. * ***
13. 13. A system according to claim 101 11 or 12 when dependent from claim s... 10, wherein a said transmitter and a said receiver of a said monitoring *s. S means are disposed on the same side of the opening.

    ** S 55
14. 14. An obstruction detection system for detecting objects in front of (as herein defined) a doorway or other opening comprising at least one transmitter and at least one receiver configured to be disposed on or adjacent the same closing vertical edge of a door or the corresponding edge of a door frame, the transmitter being adapted to direct a beam of energy obliquely forward from the said edge to illuminate an object approaching the opening from the side, the receiver being adapted to receive said energy reflected from the approaching object.
15. 15. A method or system as claimed in any preceding claim as herein described with reference the accompanying drawings.
16. 16. A lift or other structure provided with a system recording to any of claims 6to 15. * * * *** * *** * * ***. * S **e* ***** * S * S. * S S 555 *

    I e. * S