New Zealand No 335688 International No PCT/
TO BE ENTERED AFTER ACCEPTANCE AND PUBLICATION
Priority dates 07 05 1999
Complete Specification Filed 07 05 1999
Classification (6) B66B13/26, G01V8/20
Publication date 28 October 1999
Journal No 1445
NEW ZEALAND PATENTS ACT 1953
COMPLETE SPECIFICATION
Title of Invention Improvements in lift sensors
Name, address and nationality of applicant(s) as in international application form
T L JONES LIMITED, a New Zealand company of 46b Halwyn Drive, Christchurch, New Zealand
1 R 2 O
0 J V 0 U
TITLE: IMPROVEMENTS IN LIFT SENSORS Technical Fffld
This invention relates to obstruction sensing systems, particularly for sensing obstructions in a scanned volume of space between and in front of elevator doors Particularly, the invention relates to an infra-red scanning system for elevator doors
Background art
In the prior art, it has long been recognised that an effective method of detecting an object intruding into or through a specified area is by monitoring an array of light beams scanning that area A large variety of such systems, many using infra-red transmitters and receivers, are known Examples of such can be found in U3 Patent No 4650990 and WO 84/02413 However all of these scan in only two dimensions, that is over an area, not over or through a volume of space
Improvements for such systems are to be found m the specification for W096/08734 ("Thomson") This specification discloses a system for scanning over an area, usually between lift doors, which provides for communication of command signals between the spatially separate components of the emitters and receivers The command signals are contained within the optical paths between the array of emitters and receivers
However there are shortcomings to such systems In particular, there are few systems which permit the scanning of a volume of space immediately in front of lift doors as well as the area between the doors Such scanning is generally termed "3 dimensional" or "3D" scanning Despite the quality of scanners across the area between lift doors, these sensors cannot cater for a person advancing towards lift doors Often, with the manner in which doors operate, such the lift doors, in spite of quality area sensing systen ~
The scanning of a volume of spacc in front of lift doors (when open) is possible A fixed scanning sensor is disclosed in US Patent No 52S4225 However, the operation of such a sensor includes equipment additional to the sensors between the lift doors as that area is not scanncd Further, a static 3D sensor would need to be installed on every floor, rather than with the lift, thus necessitating much duplication of equipment A fmther disadvantage is that the signal from the sensors on each floor would need to be integrated with that from any lift door sensois This is sometimes not possible without considerable electronic communication and computation power associated with the lift sensor
New Zealand Patent No 272549 ("Memco") discloses a 3D scanning system using infra-red beams There is disclosed the use of primary emitter and receiver arrays of diodes for two dimensional scanning as discussed above, as well as an auxiliary set of emitters and receiveis which are angled to approximately 45° outward of the lift doors This auxiliary set, and auxiliary beam, scans the 3D space in front of the lift doors
However, the method and equipment disclosed in Memco requires that there be two sets of emitters and receivers As the secondary set operate in the same manner as the primary set (that is, on the absence of a signal), it is necessary to shield the secondary receivers from any primary beam Also, shielding of the secondary emittcis, so that no signal from these are received by the primary receivers, is necessary
The disadvantage of this system for 3D scanning is the high number of emitters and receivers required, as well as the necessary arrangement of shielding Also, separate analysis and control programming routines are necessary, as compared with area scanning requirements
A direct combination of the elements of the sensing systems of Thomson and Memco may be possible However, the disadvantages of the Memco system would still
remain, in that the necessity for an additional set of secondary emitters and receivers would still be present Such a hypothetical combination would not obviate the need for a secondary beam for the auxiliary emitters and receivers Further, the scanning method disclosed m the specification of Thomson "would require considerable adaptation to drive the sensor of Memco, if such combination were technically possible
An object of the present invention is to provide an obstruction detection system for 3D scanning which overcomes or mitigates at least some of the above described problems or at least provides the public with a useful choice
Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only
Disclosure of Invent ion
According to one aspect of the present invention there is provided an obstruction sensing system, said system including at least one first component and at least one second component, where the first and second components are spatially separate and include an array of optical emitters and receivers respectively, the emitters and receivers being arranged to define a pluialily of optical paths in an obstruction detection volume, wherein the arrays of emitters include at least one angled emitter, the or each angled emitter being set at an outward angle to the remaining emitters, and wherein said obstruction detection volume includes the area between the first and second components, and
a space 111 front of said area,
and said system further includes microprocessor and beam address logic adapted to provide control commands,
and signal piocessmg circuitry related to the detection of the direct and reflect optical signals received by the receiver array from said aiea and reflected off objects in the said space
Preferably said system further includes a control beam emitter on a first component which optically communicates control commands to a control beam receiver 011 a second component, wherein the control commands initiate one or more sets of sequential activations of emitters and receivers, the control commands also controlling the selection of the emitters and receiveis in such a manner and configuration as to form a desired sequence of optical path patterns in the obstruction detection volume, and in which the control commands correspond to the signals and the optical emitters and receivers transmit and receive the signals, said signals being of varying duration and/or timing and/or frequency where the duration and/01 timing and/or frequency correspond to specific control commands
Preferably, a signal of fixed duration corresponds to an instruction to activate subsequent leceivers m a predetermined sequence
Preferably, the predetermined set sequence of emitter and receiver activation sequences are adapted to provide a plurality of optical path pattern sequences in the obstruction detection volume, said patterns including a combination of
a pattern of horizontal optical paths scanning the said space and the said area within the obstmction detection volume,
a pattern of up-angled optical paths scanning the said area within the obstruction detection volume, the receivers being adapted to ignore any optical paths from the at least one angled emitter,
a pattern of down-angled optical paths scanning the said area within the obstruction detection volume, the receivers being adapted to ignore any optical paths from the at least one angled emitter
Preferably, the pattern combination further includes the sequence at least one pattern of one up-angled and one-down angled, crossed optical paths, using two emitters, one on each side of an angled emitter
Preferably, the control commands relate to the sequential operation of the array(s) of emitters and receivers
Preferably, the obstmction sensing system is incorporated in an arrangement of elevator doors wherein the first component comprises an infra-red emitter array adapted to be responsive to infra-red beam driver circuitry, where at least one of the elements of the infra-red emitter communicates control commands,
microprocessor and beam address logic adapted to provide control commands,
infra-red emitter beam driver circuitry, wherein the first component is located proximate one edge of an elevator door, and the second component comprises
a photodiode array adapted to be responsive to optical conditions which include received ditect signals from the emitters m the emitter array and reflected signals reflected off objects in the said space, and wherein at least one element of the photodiode array is lesponsive to the control commands,
signal processing circuitry related to the detection of the direct and reflected infra-red signals received by the photodiode array from the area between the doors and leflected off objects in the said space,
microprocessor and beam address logic adapted to be responsive to the control commands, and wherein the second component is located proximate the edge of the elevator door opposite that where the first component is located
Preferably also, each angled emitter diode incorporates a more focussed beam than the non-angled emitter diodes
According to another aspect of the present invention there is provided a method of detecting an obstruction usmg the sensing system as discussed above, said method comprising analysing optical conditions, which include direct signals from an emitter array and reflected emitted from the at least one angled emitter, which latter signals are reflected off objects m the said space, and modifying obstruction event criteria based thereon,
determining the presence or absence of an obstruction based on that cntena wherein the optical conditions correspond to the intensity of one or more optical beams transmitted or reflected in such a manner so as to define the obstruction
detection volume and wherein the presence or absence of the obstruction in the obstruction detection volume is determined from the sensed optical conditions
Preferably, the method further includes the step of vaiying the obstmction event criteria in response to changes in the dimensions or geometry of the said space of obstruction detection volume
Preferably, the method further includes the steps of sensing first optical conditions corresponding to the absence of transmitted or reflected beams, thereby determining the ambient optical conditions in an obstruction detection volume,
sensing second optical conditions with transmitted and/or reflected beams, thereby determining the transmitted and reflected total beam intensity contribution to the total optical density in the obstruction detection volume, and comparing the second optical conditions with obstruction event criteria, thereby determining if an obstruction event is present in the obstmction detection volume
Brief Description of Drawings
Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only, with reference to sensing obstiuctions between and in front of lift doors, and with reference to the accompanying drawings in which
Fig la illustrates a horizontal scan pattern of a first preferred embodiment present invention,
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Fig lb illustrates an up-scan pattern of the first preferred embodiment of the present invention,
Fig lc illustrates a down-scan pattern of the first preferred embodiment of the present invention,
Fig Id illustrates a cross-scan pattern of the second preferred embodiment of the present invention,
Fig 2 is a schematic representation of an obstruction detection system of the present invention, and
Fig 3 is a flowchart illustrating an obstruction detection procedure for use with the second preferred embodiment of the present invention
Best Modes for Carrying out i hf Invention
The scan patterns employed in the present mvention employ the same nomenclature as that of the specification for Thomson
In the examples in Fig 1, the emitters (E) are located on the lefl and the receivers on the right The emitteis generally number 24 or moie, and numbers 6, 14 and 22 (E6, Eh, E22) are angled emitters set at an angle outward from the remaining emitters E The angled emitters are positioned at substantially 45° relative to the lift doors on or between which the emitters are secured
However, it will be appreciated by those skilled in the art that more, or fewer, emitters may be used, as is desired Further, if so desired, the beam fiom the LEDs of the angled emitters may be more focussed than the lens of the non-angled emitters
The receivers are photodiodes (P) and there are the same number of receivers as there are emitters
In the first preferred embodiment of the mvention, a sequence of three scans is used in the scan cycle
Fig la shows the honzontal scan (En, Pn) arrangement within this cycle The signal from En is received by Pn and the signal received by Pn is measured With angled emitters (for example, E6) the corresponding receivers (for example P6) will receive any reflected signal, from E6
Fig lb shows an angled-up scan arrangement, in which the enntteis are sequentially activated starting with emitter E, from which the signal is received by P0 The sequence is continued in like manner until En is activated, the signal being received by Pn, In this cycle signals from E7 and other angled emitters are ignored
Fig lc shows an angled-down scan arrangement, m which the emitters are sequentially activated, starting with emitter E0 from which the signal is received by P, the sequence is continued in like manner until En, is activatec}, the signal being received by Pn In this cycle signals from E7 and other angled emitters are ignored
Figure Id show an additional, cross-scan arrangement which can be added to the scan cycle represented by Fig s la to lc, if so desired In this scan, an emitter on each side of an angled emitter (for example Es, E7) is activated The signals from these emitters cross and are received by P7 and P5, respectively
Fig 2 shows a schematic representation of an obstruction detection system of the present invention Microprocessor 39 provides control comi transmitted across the door gap
The control beam is transmitted between an emittcr/ieceivcr pair in the array (for example 35a and 36a) Micioprocessor 39 on the transmitter board controls the emitter beam driver 33 Beam address logic is indicated by numeral 34 The microprocessor on the receiver boaid is indicated by 32
Transmitter and receiver control boards 2 and 1 are mounted along the edge of the obstruction detection area (l e along the edge of the elevator doors, or slightly recessed therein) A power supply unit is mounted above the elevator car and is adapted to accept a variety of AC and DC inputs The power supply in this particular example provides a regulated 12 V supply The power supply also houses the interface relay, the audible warning alann and the alami control circuitry
Fig 3 shows a schematic flow chart for use in a preferred method of operating the scan cycles as shown in Figs la to Id
The n=0 emitter/receiver pair act as a control beam transmission means The control beam uses variable bursts of pulses with a frequency of 44 kHz
Assuming that the power-up diagnostics are successful, the scanning sequence is initiated
The initial sequence of the cycle is selected As can be seen in Fig 3, this is a horizontal scan (corresponding to Fig la) The activation of the emitter/diode pairs (En, Pn) begins The signal received by the diode receiver Pc, corresponding to the first of the angled emitters E6 is analysed with regard to the receipt of a reflected signal from the obstruction detection volume The signal received from the ordinary emitters is analysed in known manner to detennine if there is an obstruction event occurring between the doors of the lift
If no reflected signal is received at P6 (etc) this is indicative that there is no obstruction in the obstruction detection volume
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Once the initial horizontal scan cycle is completed, the second cycle is started This sccond cycle is an anglcd-up scan (corresponding to Fig lb) The activation of the cmitter/diodc pans (E,„ Pnl) begins Any signal emitted from an angled emitter (E(, etc) is ignored
Once this scan is completed, the third cycle is initiated This is an angled down scan (corresponding to Fig lc) The activation of the emitter/diode pairs (En „ P) begins Any signal emitted from an angled emitter (Eh, etc) is ignored
A further optional scan may also be analysed This is a fourth, cross-beam scan (corresponding to Fig Id) The activation of the emitter diode pairs on either side of the angled emitters is commenced For example, the signal from E5 and E7 is received and recorded at P5 and P7 respectively
This additional scan in the cycle may be used, for example, where there are fewer than usual emitter/receiver pairs This scan is intended to cover the area between the doors left unscanned in the previous three scans within each cycle
The flowchart and operation of the electronics associated with each scanning cycle is otherwise as disclosed in Thomson
Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto without departing from the scope thereof as defined in the appended claims
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