CA1167950A - Object sensing apparatus - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
An object sensing apparatus includes a plurality of light emitting diodes for illuminating region of space and a plurality of closely arranged light detectors for receiving light reflected from an object. The apparatus is particularly useful in correct on with automatically operated doors.

Description

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SPECIFICATION
BACKGROU~D OF TE~E INVENTION
: ~he present~invention~rel tes to an apparatus ::
~or sensing the presence of objec~s within a sel ted reglon~o~ space. In~ particular ~he present i~vention~
relates~to ob~ect s:ensin~device ~which are us~ful i~
~5 ~ co~nectLo~ with ;the~operation~of automatic~doors or:o~her automatIcally moving~equipment.:~
In ac~cordance~with~ e pri~or art, lt has been~
k~o~n to make use~of light~or~radiation emitting~equipment : and radiation detecting eauipment: for the~purpose o~ sensin 10: t~he presence~of an~object ~or person~in a partic~lar r~io~
~: of space.~ One~applicatlon~far s:uch~object sensing equipment :; :is in~cannecti:on:wi:th~;~ e operation of an aut~matically opera~ed door. In thi5 case it is desirable to ~rrange the equLpment to~sense ~he approach of a person or an object, 15~.: such as~a:shoppLng cart, ~rom one direc~io~ O! the door in :order ~o activate the door to move it to the open position.

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It is likewise desirable to sen~e the pr~s ~ce of an object or person on the opposite side of t.he door tO
prevent the door from striking the person during the opening operation. Another sensing function is to determine when 5 the person has passed through the doorway, and clear of 'rhe swing of the door, to ena~le closing of the door af'cer the person has ~ntered through the doorway.
The most reliable method fGr sensing the p~esence of a person know~ in the art is to provide pressu:re sensitive 10 doormats which provide a signal in response to ~he weight of a person standing thereon. Such doormats must be pro-vided on both sides of the door. On the approach side the doormat senses the presence of a person who wishes to pass ~hrough the doorway. On the inside of ~h~ door, in ~he area which includes the swi~g path o f the door, the mat -is provided to sense the presence of a person or object in the pa~h of ~he door and provides a signal which preYen~s . the d~or ~rom opening and causing injury to the person or damage to: the object thereon. The inside wing pat~h doorm2t is also used to prevent closing of the door during the time when a person is passing through the doorway. After there is no weight on either of the doormats the door is permitted to close.
The use of pressure sensi~ive doormats i~ connectio~
25 Wlth t~he operation of a swinging door in accordance with the prior art, while being the most reliable method for detecting ~he presence o~ a person or object, h~5 a disadvantage, which is nor~ally associated with the use of a doormat i~stallation :`
on a high tra~fic floor. The doormats used to sense the ~7~

presence of ~ person or object are subject to wear ~rom the passage of traffic ~hereov~r. In addition, ~he doormats are usually in an o~tdoor entry loca~ion where they will be subje~ted to rainwater and to damage from ice, snow, and possibly salt o~ othex corrosive chemicals used to clear ice and sn~w.
A further problem with the door~t sensing devices is the fact that it beomces difficult to ~ell when the device has failed. Failure of the swing path doormat can result i~ injury to a person and consequent liability to the owner or occupant of the premises i~ which the door has been installed.
There have also been provided object sensing .
devices wXerein a radiation source is provid d which sends radiation along a selected path at a radiation sensing 15 element. When an ob~ect or person enters the path: of -the radiation, the absence of the radiation being~received at the sensing element provides an indication that there is an object or person in the path of the beam. The use of this beam-path type sensor provides a certain n fail safe" re-liability because ~f the fact that a beam must pass com-pletely ~hrough the path in order to be detected and provide an indication OL a safe condition. It becomes neces~ary, however, in connection with the operation of a swinging door, ~ to pro~ide a great many e~l tters and detectors to provide adequate assura~ce that a small child is not within the path of the swinqing door.

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U . S . Patent 3, 852, 592 ~o Scoville describes a prior art door opening control apparatus which includes n e~itter mounted above the doorway which sends infrared xadiation along ~ downwardly directed energy beam which spans a path of travel of pedestrian traffi~ approaching the doorway.
- There is provided a sensing element which i5 mounted on ~he jam of the doorway and which has a receiving beam pa~tPrn of sensitivity which is generally horizontally disposed, so that ~here is p~ovided an intersection of the infrared radiation beam ~rom the ~mitter and the horizontal sensing beam pattern fxom the re~ceiver, which defines a protected area in space. The patent states that addi~ional emitters may be provided, as required, to provide additional protect;on in additional regions in space.
While the appara~us described by Scoville ~ay be effective in ordinary ~ircumstan~es for detecting objects which are in the re~ion defined by the intersectio~
of the two beams, problems may arise from the fact that the door swings into the region of lntersecti~n o~; the two 2Q be~ms, and may provide some interfexence with operation of .; the system. In addition, the system may be sensitive to its installation, since the emitter and the detector are located at different locatlons, a~d the operation of these devices is sensiti~e to their locations and to thelr en~iror.-~ men~. Further, the system may fail to detect small objects~
. ~or example an in~a~t crawling below the horizontal beam.

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~ t is therefore an ob~ect of the presentinventon ~o provide a new and improved object detectiny apparatUs.
~ t is a further object of the precent invention to provide such an apparatus which h2s a single location S ~or emutters and detectors~
I~ is a further object of the prese~t invention to pro~ide su~h an apparatus which is less sensi~ive to the ~nvironmen~ of its i~stallation, and is less sensitive to changes i~ the reflectivity of ~hs object to b~ detected.

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In accordance with the invention ~here is provided a control apparatus for an autom~tic door which has a motor operated means for swinging the door open in a selected ~irst direction path from a door frame in response : 15 to the approach of an object fro~ a second direction, and ; f o~ i~hihi ting o peration o f ~he motor operati~g means in response to the presence of an object in the ~i~rst direction path of ~he door~ The control apparatus includes first and se~ond object sensing appara~us mounted on:~the door a~d facing respectively in the_first and seco~d directions from the doox. The first and sec~nd sensing apparatus each consists of a plurality o transmitting elements for emitting a di-verging beam of radiation in response to supplied electrioal signa}s,~ and means for simultaneously supplying electrical signals to all of the elements in each sensing apparatus t Each sensing apparatus also includes a plurality of radiation detecting elements for receiving radiation reflected from ; an obj~t, and a receiver connected ko the de~ecting elements ~or provlding an output signal representative af the presence o~ an object. The apparatus also includes a control circui~

for (1~ acti~ating the motor means to vpen the door in response ~o an output signal from the sec~nd sensing appa-atus, ;..

~;7~3 ~ 2 ) activating S~he mc>tor mear~s to main ain t~e d~or in an open posi~ion ln response to an outpu~ signal from the second sensing apparatus and (3) inhibiking operation of the motor means and preventing opening of ~che door in response to an output signal from the first sensing ~ppara~us.
The control apparatus can be arranged so that the control circuit is no~c operative to inhibi opening of the doi~r af ter t~e motor means is opexated and the door is opened by a selected amount. This preven.ts the presence of a railing or a wall adjacen~ door opening from preventing further opening of the door. There may also be provided a radiation e~itting means arranged to direct radiation along a path to the detecting elements of ~he first sensing apparatus when the door is opened. The control means is then arranged t o activa~e the emitting means after the door is opened by a selected amount, and `~ the control means is arr~anged tD inhiblt operation of the motor means upon obstruction of~the path between ~he emitting means and ;the detecting e1ements of the first sensing apparatus.
The sensing apparatus of the invention may also be used in connection with machine tools, automatic transport ~ehicles, elevator doors and similar equipment for preven ing such equipment from s~triking~an object or person.
: ~or a better unders~anding of the present invention, together with other and further objects, reference is made .
to:~the fvll~wing description, taken i~ conjunction with the occompanyin~g drawinss, and its scope will be pointed out i n th~3 appendea claims.

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BRIE~ DES CRIPTION 9F THE DRAWINGS
~ ig. 1 illustrates the sensing apparatus of ~che present irlvention in schematic form.
~ ig. 2 illustrates the sensing apparatus of the 5 present irlvention as installed on an au~omatic opera,ing door.
Pig. 3 is a ~op view 4f the door o~ ~ig. 2.
Fig. 4 is a side view of the door of Fig. 2 illus~rating t~e rad~ a~cion and rec:eiving patterr. of the sensor assembly .
~ig. 5 is a top view of the ~ig. 2 door illustrating the sensor assembly transmitting and receiving pattern.
Fig. 6 is a cross-sect~ on view of a sensor as~embly suitable for use in connection with the door of Fig. 2.
Fig. 7 is a front ~iew of the sensor assembly of Fig. 6.
Fig. 8 is a schematic diagram of the Fig. 6 sensor assemblv.
Fig. 9 1S a b1Ock diagram illustrating the arrange ment o~ ~ the control apparatus usable for oper ing the door of Fig. 2.

DE~ P~ )N ~ I~ ON
In ~ig. 1 the~ is shown a schemati~ diagram of the sensox~ ass~bly in accordance Wit'.l the present i~vention.
In ~he~Flg. 1, diagram the sensor asseIrbly 10 includes a source 12 for generating electrical signal~, preferably p-~lse signals having a pred~termined frequency such as a few kilohextz.
The output of sign 1 souIce 12 is provided to light-emitting 2~41 -' J 1~7~t diodes, which are ~onnec~ed in series wi~h signal source 12.
Those skilled ir~ the art will recognize that it will also be possible to connect the light-emitting diodes lJ, in parallel with the output of sigr~al source 12, according to 5 the voltage output of ~he sig~al source and the impedance of the diodes. Each of the light-e~nitting diodes 14 is arranged to radiate a di~7erging patterrl of radiation. In the embodiment illustrated in Fig. 1 the light-emit~ing diodes 14 are each arranged to radiate in a conic21 pattern with an interior angle 18 which is approximately equal to 90.
Accordingly, objects 22, 24 and 26, which are wi~hi~ ~he radiation pattern of one or ~ore of the light-enitting diodes 14 will receive radiation such as opticaI or infra-red radiation, which is emitted from the diodes.
lS The sensor assem~ly~ of Fig. 1 also ~includes a plurality of radiation detectillg elements 16, such 2s photo-transistors. The photo-transistors 16 are arranged to have a diverging beam of radiation sensitivity, appro ~ mately the same shape as the beam o. ~the :Ligh:t-emittins diodes 14.
20 Accordingly, lisht or infrared radiation, eraitted by light~
emitting diodes 14, and re'lected fro= an objest 22, 24 or 26 within the region o~ space illuminated by the sensor asse~nbly, will be reflected back into the light detecting elements 16 ~and~ geDera~e therein an electrical signal. It shc~uld be 25 noted that because of the diverging beams of radlation of the light-emitting diodes 14 and the diverging beam of sensitivity of the light-sensing elements 16, it will be possible for radiation, emitted by ar~y of the diodes ~ to be ~4~41 ~7~t~) re~lected off an object in the object field and received by a plurality of the light-sensitive elements 16. This ~eature tends to increase the sensitivity of the sensing apparatus for rela~ively cl~se objects, and thereby enables the easy detection ~f objects in the adjoining region of space, even i~ those objects have varying amounts of radiatio~ re-~lectivity at the frequency of emission of ~he light sources 14.
The light sensing elements 16 are connected in parallel and their outpu~ signals are provided as an input to receiver 20. ~eceiver 20 preferably includes a tuned amplifier which is responsive to frequencies in the range of the output f.requency of electrical si~nals from signal sourc~
: The detect~ng apparatus of Fig. 1 is particularly useful in conn~ction with automatically operated mechanical : equipment~for sensing the presence of an obstacle. In this : respect, the sensing apparatu~ of Fig. 1 is preferred to the `~ ~ conventio~al reflection type object sensing apparatus by : reason o~ the fact that it has a drastically reduced ran~e of sensitivity to an object, and is less susceptible to variations in object detecting range with varia~lon in radiation reflectivity of the object. Prior art reflect;on :
type object sensing apparatus'~kes use of a focused beam of light, which~:is directed o-ltward in the dirPction from 2S which an objec~ is anticipated to approach. The radiation is reflected ~ff the object and recei~ed by a sensing apparatus which also:has a relatively narrow focused beam which is oriented in the identical direction. The range at which _g_ 242~1 7~

an object will be sensed by this 'cype of apparatus will depend largely on the reflectivity o~ the object. An object such ~s a re~:ro-reflecting device, which sends back a re-latively ~ocuse d be am o f radi a ~ci on t~w a rd the emi tter wi ll 5 cause a very large response in the receiving device and may be detected at a very large range. ~ object which has relatively low reflectivity, such.as a dull black overcoat, will not be detected until it is very close to the radiation detec~or.
3ecause the sensing apparatus illustrated in Fig. 1 uses diverging rather than focused beams of radiation for both the radiation emitting devices and the radiation detecting devices, it is susceptible to receiving and res?ondins to radiation reflected off objects only within a limited range where multiple emitters illuminate the object and multiple receivers detect the reflected sig~al. Therefore, the radiation detector iS not likely to respond to an object at a relatively far distance, éven i~ tha~ object is highly reflective, since both the illuminatior. of the object and the sensltivity of the detectors is greatly reduced with distance as compared to focused beam illumi~ation and detecting devices. In contrast, :the sensing apparatus will respond relatively strongly to an object which is relatively close, beca~e even thou~h the re~lection from ~h~ object may be di fused ~nd scattered ! it will be received by multiple ~etecting elements in the receiving array, and therefore, : the outputs of these elements as currents will add in ~he receivex, and provide an adequate response to provi de an ~utput indication of the presence of the object.

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Fig. 2 is a perspective view and Fig. 3 is ~ top cross-sectional view of an automa~ically operated door 30 having a sensing apparatus 10 in accordance with the presen'c invention. The door 30 is mounted within wall 28 and is S opened and closed by means of a motor apparatus 33. On each side of the door there are provided guard rails 34, 36, 38 arld 40 , which are arranged to prevent appr~ach t~ward the door from directions other than straight-on. The door o~ Fig. 2 is arranged to open in a first direction which is away frc)ra the side lllustrated in Fig. 2, ~nd alons the pa~
31 to the position 30' which is illustrated in Fig. 3. Op~qing of the door 30 by motor 33 is effected in response to the detection of an object by sensing apparatus 10, w~ich is mourlted 021 the side of the door illustrated in Fig, 2 facing ln a second direction with respect to: the door.
T~e door is provided with a second object sensing apparatl~s 15 which is mounted on the sIde of the door facing in the ~i~st direction corresponding to the door opening path.
Sensi~g apparstus 15 is utilized by the door con,~ol a~pa_a,us to prevent opening of the door when there is an obstruction in the path of the door, such as a person standing ~ex* to the door. The sensing apparat~s 15 inhibits the opera~ion of the door when an object or person:is sensed in its path i n order to pre~ent damage to ~e door or inj~ to the person.
Z5 ~ The object sensing devices 10 and 15 which are mounted on the door 30 are illustrate~ sc:~ematically in ~ig. 1. Fi~s. 4 and 5 illustrate respectivPly the elevation , .

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and azimuth radiation transm~tting and receiving beams for the sensing devices 10 and 15 The appar~tus 10 has a radiati~g surface which is anslea at approximately 30 ~rom the vertical in order to orient the elevation radiation S beam in a slightly upward ~rom horizontal direction. The radiation beam has an approximately 90 half power beam width so that it radiates in~o an area 42 illustrated in elevation in Fig. 4 and in zzimuth in Fig. 5. The device 10 is mounted approximately 15" above ~he floor on door 30 to detect objects near the bottom of the door.
The radiation sens:ing apparatus 10 is illustrated in grea~er detail in Figs. 6 and 7. The apparatus includes a pair of U-shaped channels 46, 4R, made of opaque material, such as extruded aluminum. The channels have an outer surface whlch is CUt o~f at the 30 angle illustrated in Fig. 4, and they~are covered by ~ light transmutting cover 5~, preferably have a:tinting suitable t~:transmit and re~eive primarily radiation in the freq~ency band of oper tion of the light-emltting diodes 14. The light-emit.ing diodes 14 are containe~ in the upper channel 46. The photo-sensitive transistors 16 sre~ cont5ined ln a lower-channel 48. The 1QCatiOn Of the light-emitting d odes -and photo-sensitive ;

transistors ln ea d o~ the channels l5 such ~s to provide tne O radistion beam width which is illustrated in Fig. 4 and shown as dotted lines in Fig. 6. ~t the bottom of each o ~he chsnnels 46 and 48 of the extruded membex 44, there are prov~ded circuits 52 for connecting the light emitting diodes and the photo transistors to the signal generating and receiving apparatus.

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In the front plan view of ~ig. 7, ~he spacing of the elements of the sensor assembly 10 is illustrated in greater detail. In ~he preferred e~mbodiment illustrated, the light-emittir.g diodes 14 are arran~ed with approximately : equal spacing along a first path which consists of a horizontal straight line down the center of ~le upper ~hannel 46. The photo t~ansistors 16 are arranged with sLmilar equ~l spacing, interspersed with the diodes 14, along ano~her straight path, : wh ch c~nsists 9- the center line of the lower channel 48.
The spacing between adjacent photo transistors ~nd light-10 emitting diodes, design2ted spacing A in Fig. 7, is pre ~erably selected to be approxi~ately 20 mullimeters or less.
; ~ The spacing B between .he paths on which are located the light-emltting diodes 14 and the photo transistors 16 is preferably no more than 16 millimeters. S~acings A and B
which are greater than ~he recommended am3unts ha~e been found ~o maXe it dif~icult to o~tain a response from , small objects, such as ~ticks the size o~ fingers, within :: the region of spaçe 42 illustrated in Figs. 4 and 5.
With the suggested spacing the device 10 will sense small objects out to a distance of approximately ~ to 8 feet.
Natu~ally the range of the sensing apparatus can be adjusted according to ~e intensity of the diodes 14 and the sensitivitv : of the detect~rs 16 a~d the receiver.
Fig. 8 is a circuit diagram illustrating the ~ixcuits for the sensing apparatus 10. As illustrated in Fig. 8 the light-emitting diodes are co~nected in series to a signal source 12, and optically coupled to the photo transistors by means of re1ection off an object~ Photo translstors 16 are ~onnected in par~llel to drive a t~ned ~ ~7~f1 amplifier 54 in the receiver 22., The output of the t~ned am~lifier is detected by a rectifier 56 and pro~ided to a DC amplifier 58 which can operate a relay or other deci~io~
logic used in connection with the operation of the door.
~ig. 9 illustra~es a block diagram of the control apparatus usable in connection with the door 30 of Fig. 2 The contxol unit, which may be a programmed microprocessor or equivalent logic circuits, is connected to sensing apparatus 10, sensing apparatus lS and also in a preferred embodiment khere may be provided an additional light source 32 which is arranged on barrier 40 as illustxated in Fig. 3.
The output of the control unit is connected to motor 33 and is ~rranged to operate the motox to open and close the door 30.
The control circuit illustrated in Fig. 9 under normal conditions operates to open the door in response to an object detec~ing signal emitted by detecting apparatus 10.
Detect;ng apparatus 15 operates to inhibit activation of door openins when an ob j ect obs tructs the door . Accordinsly control unit 54 will not open the door when a signal is received from ~nit lS, even if a signal is received from unit 10.
It will be recognized tha. as door 30 opens contr~l unit 15 will respond to the presenee of barrier 40 in the path of~the door and provide an output indication to control unit 54 indicating that an object is in the path~of the door. This, under oxdinary circumstances, would s~op khe further opening of the door. In order to `
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~ ~7~5~1 prevent this false detection, ~he sensi~g u~it 15 is inhibited by a signal ~rom position switch 56 which indica~es that the door has ope~ed to a certain selected angle, for example, position 39. Signals received from detecting apparatus 15 indicating the presence of an object in the path of the door are no longer operati~e to prevent ~he control un' t from effecting the con~inued opening of the door a~ter switch 56 is activa~ed. Such inactiva,ion of ~he operation o~ sensing apparatus l; may cause a hazardous condition because of the fact that, after the control unit is inhibited, a child can enter the path of the door and be injured by the door. In order to provide further safety under this circumstance, barxier 40 may be provided with light-emitting means 32 which emits light in the direction of Senslng apparatus 15 af ter the position switch 56 is activated by opening of the door to positio~ 39. Thexeafter light passes directly from unit 32 to detecting apparatus 15, and causes an output signal from apparatus 15. At this poi~t .
. the output signal from apparatus 15 is considered to be a positive signal, and the further opening of the door will : be inhibited only upon the interruption of the Iight path between unit~32 and detecting apparatus 15.
In many automatic door installations based on the present inventionj it will be desirable to provide a .
suitable fixed sensing system for detecting objects which : ~ approach the door when it is partly to fully open, Because : : the diveryent beam 42 from the 5ensin~ apparatus lO mounted .

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on the approach side of the door 30 (see Fig. 5) move~
with the door, it is lncreasingly less apt to detect objects approaching the door, the wider open the door is.
Th~refore, if an object follows behind another object at a distance 5uch that the first object leaves ~he detection field as the second object approaches, there will be a period when the beam 42 cannot detect the approach of the second object toward the door opening, and the door may begin to close as the second object approaches or begins to pass through. Hence, a fixed position detection device, such as anotner sensing apparatus in accordance with the present invention or a microwave apparatus, located~above the door or to eitner side of the approach pat~, should be provided to detect objects approaching when t:e door is partly to fully open. The fixed-position detector can be normally de-energized and energized in accordance with~door position only when the door is partly to fully open and can override the sensing apparatus 15 and keep tne motor apparatus~33 2nergized whenever it ; 20 detects an object approaching the door.
~While the preferred embodiment O~ ~h^e invention hzs been de~scribed ln connection with 2 motor o~erated swinglng~door, tnose skllled in the art will recogni~e tnat thls and other em~odiments Wil7 be useful in connection with sliding doors, elevator doors, sel.
operated vehicle5 or other automatically movins devices.
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While I have described what I believe to be the preferred embodiments o~ the invention, those ~killed in the art will recogr.ize that o~her and further changes and modifications may be made thereto, and it is intended to claim all such chaDges as fall within ~he true scope of the invention.
The term "light radiation" as used in the accompanying claims is to be understood as including the infra-red, visible and ultravlolet regions of the spectrum.
This is a division of Canadian Patent Application Serial No. 353,057, filed May 30, 1980.

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Claims (3)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Control apparatus for an automatic door having motor operated means for swinging said door open in a selected first direction path from a door frame in response to the approach of an object from a second direction, and for inhibiting operation of said motor operated means in response to the presence of an object in said first direction path of said door, comprising:
a first object sensing apparatus, mounted on said door and facing said first direction;
a second object sensing apparatus, mounted on said door and facing in said second direction;
said first and second sensing apparatus each comprising a plurality of elements, each for emitting a diverging beam of light radiation in response to supplied electrical signals, means for simultaneous supplying electrical signals to all of said elements, a plurality of light radiation detecting elements for receiving radiation reflected from an object, and a receiver connected to said detecting elements for providing an output signal represen-tative of the presence of an object;
and a control circuit for:
(1) activating said motor means to open said door in response to the output signal from said second sensing apparatus, (2) activating said motor means to maintain said door in an open position in response to the output signal from said second sensing apparatus, and (3) inhibiting operation of said motor means and preventing opening of said door in response to the output signal from said first sensing apparatus.

2. Apparatus as specified in claim 1, wherein said control circuit inhibiting operation is not operative after said motor means is operative and said door is opened by a selected amount.

3. Apparatus as specified in claim 1 or claim 2, wherein there is further provided radiation emitting means arranged to direct radiation along a path to said detecting elements of said first sensing apparatus when said door is opened, and wherein said control means is arranged to activate said emitting means after said door is opened by a selected amount and wherein said control means is arranged to inhibit operation of said motor means upon obstruction of said path between said emitting means and said detecting elements of said first sensing apparatus.