CA1221435A - Object detecting apparatus including photosensors for restricted detection area - Google Patents
Object detecting apparatus including photosensors for restricted detection areaInfo
- Publication number
- CA1221435A CA1221435A CA000479069A CA479069A CA1221435A CA 1221435 A CA1221435 A CA 1221435A CA 000479069 A CA000479069 A CA 000479069A CA 479069 A CA479069 A CA 479069A CA 1221435 A CA1221435 A CA 1221435A
- Authority
- CA
- Canada
- Prior art keywords
- light
- phase difference
- receiving
- light beams
- detecting apparatus
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
- G08B13/181—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using active radiation detection systems
- G08B13/187—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using active radiation detection systems by interference of a radiation field
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
- G01S17/04—Systems determining the presence of a target
Abstract
ABSTRACT OF THE DISCLOSURE
An object detecting apparatus of a restricted detection area, which comprises means including many light emitters sequentially actuated for projecting sequential light beams, first means for receiving the light beams directly from the light projecting means, second means for receiving any reflected part of the light beams back from an object in the area, means for receiving an output of the first light receiving means and providing a reference phase for the projected light beams, means for receiving an output of the second light receiving means and providing a detection phase for the reflected part of the light beams, means for continuously actuating only a part of the light emitters which corresponds to the reflected part of the light beams received, and means for restricting the detection area by restraining an output from a phase difference discriminating means to an alarming means when a difference between the reference and detection phases is not within a predetermined range, whereby the detection area can be restricted to a desired range, and the alarm means can be retained non-operative unless the object remains continuously in the area to avoid any malfunction with any transitory object, while the light projecting means actuated in a very short time sequence accelerates the detecting operation with minimized power consumption.
An object detecting apparatus of a restricted detection area, which comprises means including many light emitters sequentially actuated for projecting sequential light beams, first means for receiving the light beams directly from the light projecting means, second means for receiving any reflected part of the light beams back from an object in the area, means for receiving an output of the first light receiving means and providing a reference phase for the projected light beams, means for receiving an output of the second light receiving means and providing a detection phase for the reflected part of the light beams, means for continuously actuating only a part of the light emitters which corresponds to the reflected part of the light beams received, and means for restricting the detection area by restraining an output from a phase difference discriminating means to an alarming means when a difference between the reference and detection phases is not within a predetermined range, whereby the detection area can be restricted to a desired range, and the alarm means can be retained non-operative unless the object remains continuously in the area to avoid any malfunction with any transitory object, while the light projecting means actuated in a very short time sequence accelerates the detecting operation with minimized power consumption.
Description
3~
"OBJE.CT DET~CT:[MG APPARATUS INCLUD:ING PIIO'I'OS~NSORS
FOR RESTRICTED DETE.CTION AR~A"
SP~CIFIC~TION
TECHNICAL BACKGROUND OF THE INVENTION
This invention relates -to an objec-t de-tec-tiny apparatus including pho-tosensors which can se-t their de-tection area to be of a restricted range.
The object de-tecting apparatus of the -type referred to is arranged so tha-t a light projecting means emits a light beam or infrared beam so -that, when an object exists in the path of -the beam, the beam reflected -to return from the object will be detected through a light receiving means to provide an alarm, and is effectively utilized specifically as a burglar alarm or the like.
DISCLOSURE OF PRIOR ART
A known intrusion detector which employs a photosensor has been suggested in, for example, U.S. Patent No. 3,727,207 of Danilo V. Missio et al., which comprises means for transmit~ing a laser beam to a target fixed at an end of a desired detecting path of the beam, means for receiving the beam reflected from the target, means for converting received ligh-t to an electric current signal and amplifying the signal, and means for detecting the voltage level of the amplified signal and discriminating both transmission time and reception time of the laser beam on the basis of the detected voltage level, ~IL2;~3~
so that a presence oE any trespasser ln -the patll of the laser beam wlll be detected in the form of a reflection time of the trespasser on the basis of a reference reflection time with respec-t to the fixed target and an alarm will be thereby generated.
This known detector, however, has a problem that, though the intention is to detect a human trespasser, erroneous detection and alarming have been caused to occur even with any o-ther object not in-tended, i.e., such a small animal as a dog, bird or the like, so long as it is present in the detection range defined by the beam path from the detector to the fixed target. Such malfunction tends to occur frequently in this type of object detecting apparatus to lower its reliability in respect of the alarming, and the apparatus has not been used widely as the burglar alarm.
Further disclosed in German Patent Application No. P2014681.0 of W.~. Nocke is a distance measuring apparatus which comprises means for projecting a modulated light beam, means Eor directly receiving the beam projected and not reflected by an object to be detect~d, means for receiving the beam reflected by the object, means for receiving an output of the direct beam receiving means to provide a reference phase, means for receiving an output of the reflected beam receiving means to provide a detection phase, and means for determining a difference between the ~2~3~
reference and detection phases. With such an arrange-ment, a distance between the apparatus ancl the object can be obtained accordiny to the magnitude of the phase difference. When the thus obtained result is utilized for detecting an intruding object and the mounting position of the distance measuring apparatus is optimumly -taken into consideration, it is possible to omit a range expanding Erom the ground face to a.
height of the mounting position from the detecting area, whereby its erroneous operation responsive to a child or such a small animal as a dog or the like can be avoided.
In this case, however, there still arises such problem that an intrusion of such a small flying 1S animal as a bird or the like into the path of the beam causes the apparatus to operate erroneously while an object that does not intersect the beam path which is single according to this known apparatus cannot be detected at all. Such malfunction with respect to the small flying bird or the like object may be avoided by setting the bsam projecting time to be relatively long, that is, to be longer than the passing time of the transitory small object, and also prolonging the beam reception and detection time. As will be readily understood, on the other hand, there still arise further problems that power consumption required for the beam projection becomes large, and that a use of, ~or example, an inexpensive light emitting diode as the bearn projecting e:Lement will resul-t in a poor durabl:Lity oE the apparatus due to easy deterioration of the diode in a shor-t time.
Fur-ther, there has been disclosed in Japanese Patent Appln. Laid-Open Publica-tion No.
120875/82 of S. Tutumi et al. a de-tection technique wherein a light projecting means including a plurality of relatively inexpensive ligh-t emitting diodes projects simultaneously a plurality of light beams, and a light receiving means also havina a plurality of light receiving diodes receives simultaneously reflected ones of the light beams with the receiving diodes corresponding to the emitting diodes of the reflected beams, so that a detection area corresponding to that of the projected light beams can be obtained.
In this case, the detection area can be of a certain expansion but it is still impossible to restrict the practical detection to a specific range within the area. Yet,the projection of the light beams is continuous during the use, so that the power consumption will become large and the inexpensive light emitting diodes will be fast deteriorated.
SU~MARY OF THE INVENTION
A primary object of the present invention is, therefore, to provide an object~detecting apparatus which is capable of restricting its de-tection area to a desired range, eliminating any malfunction with respect to a small flying animal or the like, 3~
employing :inexpensive l:Lght emitt:i.llg elements as L:ight projecting means Eor minimi~ lg recluired power consump-tion, and sti.ll. achieving a high rel:iab:ility and excel:lent economization.
Accorcling to the present invention, the ob-ject can be realized by providing an object detect:Lng apparatus of a restricted detection area, which comprises a p]ura-lity of light projecting means arranged in a row to be respectively independently actuated to project a row of light beams, scanning means for sequential actuation of the light projecting means at least in a plurality of groups, first means for receiving the :Light beams directly as projected from the respective light projecting means and not as refl.ected to return Erom a reflecting object, second means for receiving the light beams projected by the light projecting means and reflected by the reflecting object, means for receiving an output of the first light receiving means to provide a reference phase for the light beams projected, means for receiving an output of the second light receiving means to provide a detection phase for the light beams reflected and received~ means for determining a phase difference between the reference and detection phases, an alarm means operated by an output provided by the phase difference determining means, and area restricting means for restraining the output provi-sion of the phase difference determining means to the alarm means when the phase difference is of a level not within a pre-determined range.
Other objects and advantages of the present in-vention shall become clear from the following description of the invention detailed with reference to preEerred embodiments shown in the accompanying drawings.
BRIEF EXPLANATION OF THE DRAWINGS
.
FIGURE 1 shows schematically in a front elevation a relationship between the projection of the light beams and the reception of the reflected light beams by the light projecting means and second light receiving means in an embodiment of the present invention;
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-- 6 ~
~2~.~3~
~IG. 2 shows also schematica:Lly :Ln a s:Lde eLeva-tion a relationship between the light beam projection and the reception by the :Eirst light receiving means in the embocliment of FIG. I;
FIG. 3 shows in detail to some extent an example of arrangement oF the :Light projecting ancl receiving means in FIG. 1 which includes light emitting elements ancl a light receiving element;
FIG. 4 shows in a front elevation a restricted detection area formed by the light projecting means of FIG. l;
Z~43~
FIG. 5 shows in a side elevation the detection area of FIG. 4;
FIG. 6 is a block diagram of an embodiment of a projected and received light signal p:rocessing means in the apparatus according to the present invention;
FIG. 7 is a detailed circuit diagram of the processing means in FIG. 6;
FIG. ~ shows waveforms of signals appearing at a part of the circuit of FIG. 6 or 7;
FIG. 9 is a circuit diagram in an embodiment oE the scanning means of the apparatus according to the present invention;
FIGS. 10 and 11 show waveforms of output signals o~ the scanning means of FIG. 9;
FIG. 12 shows schematically in a side elevation similar to FIG. 2 a relationship between the light projecting and receiving means in another embodiment of the apparatus according to the present invention;
FIG. 13 is a block diagra.m of another embodiment of the projected and re~eived light signal processing means used in the embodiment of FIG. 12;
FIG. 14 shows waveforms of output signals appearing a~ various points in the circuit o:E FIG.
13; and FIG. 15 is a circuit diagram oE another embodiment of an amplifier in the circuit of FIG. 6 or 7.
While the present i.nvention sllall now be descxibed with re:Eerence to the preEerred embodirnenl:s shown in the drawings, it should be understood -that the inten-tion is not -to limit the invention only to the par-ticular embodiments shown but rather to cover all altera-tions, modifica-tions and equivalent arrange-ments possible wi-thin the scope of appended claims.
DISCLOSURE OF PREFE.RRED EMBODIMENTS
ReEerring to FIGS. 1 and 2, there is shown an object detec-ting apparatus according to the present invention and vertically installed against the ground face GF, which apparatus comprises a light projecting means 11 includinga light projec-ting array 12 of a plurality of light emitting diodes 121,..., and 12n arranged substantially in a row as shown, for e~ample, in FIG. 3 to project beams of light pulse-modulated to be of a burs-t wave and respectively in diEferent directions but lying in a single plane. Disposed in such optical path o~ the array 12 are a collimator lens 13 and a half mirror 14 tilted by a proper angle so -that light beams Ls emitted from the diodes of the array 12 will pass through the lens 13 and reach the mirror 14, where a part of the light beams LB
is reflected by the mirror 14 to be directed toward a first light receiving means 15, while the remainder beams are caused to pass through the mirror 14 and to be reflected by such a fixed reElecting body as the ground face GF as well as such an object SO to _ g _
"OBJE.CT DET~CT:[MG APPARATUS INCLUD:ING PIIO'I'OS~NSORS
FOR RESTRICTED DETE.CTION AR~A"
SP~CIFIC~TION
TECHNICAL BACKGROUND OF THE INVENTION
This invention relates -to an objec-t de-tec-tiny apparatus including pho-tosensors which can se-t their de-tection area to be of a restricted range.
The object de-tecting apparatus of the -type referred to is arranged so tha-t a light projecting means emits a light beam or infrared beam so -that, when an object exists in the path of -the beam, the beam reflected -to return from the object will be detected through a light receiving means to provide an alarm, and is effectively utilized specifically as a burglar alarm or the like.
DISCLOSURE OF PRIOR ART
A known intrusion detector which employs a photosensor has been suggested in, for example, U.S. Patent No. 3,727,207 of Danilo V. Missio et al., which comprises means for transmit~ing a laser beam to a target fixed at an end of a desired detecting path of the beam, means for receiving the beam reflected from the target, means for converting received ligh-t to an electric current signal and amplifying the signal, and means for detecting the voltage level of the amplified signal and discriminating both transmission time and reception time of the laser beam on the basis of the detected voltage level, ~IL2;~3~
so that a presence oE any trespasser ln -the patll of the laser beam wlll be detected in the form of a reflection time of the trespasser on the basis of a reference reflection time with respec-t to the fixed target and an alarm will be thereby generated.
This known detector, however, has a problem that, though the intention is to detect a human trespasser, erroneous detection and alarming have been caused to occur even with any o-ther object not in-tended, i.e., such a small animal as a dog, bird or the like, so long as it is present in the detection range defined by the beam path from the detector to the fixed target. Such malfunction tends to occur frequently in this type of object detecting apparatus to lower its reliability in respect of the alarming, and the apparatus has not been used widely as the burglar alarm.
Further disclosed in German Patent Application No. P2014681.0 of W.~. Nocke is a distance measuring apparatus which comprises means for projecting a modulated light beam, means Eor directly receiving the beam projected and not reflected by an object to be detect~d, means for receiving the beam reflected by the object, means for receiving an output of the direct beam receiving means to provide a reference phase, means for receiving an output of the reflected beam receiving means to provide a detection phase, and means for determining a difference between the ~2~3~
reference and detection phases. With such an arrange-ment, a distance between the apparatus ancl the object can be obtained accordiny to the magnitude of the phase difference. When the thus obtained result is utilized for detecting an intruding object and the mounting position of the distance measuring apparatus is optimumly -taken into consideration, it is possible to omit a range expanding Erom the ground face to a.
height of the mounting position from the detecting area, whereby its erroneous operation responsive to a child or such a small animal as a dog or the like can be avoided.
In this case, however, there still arises such problem that an intrusion of such a small flying 1S animal as a bird or the like into the path of the beam causes the apparatus to operate erroneously while an object that does not intersect the beam path which is single according to this known apparatus cannot be detected at all. Such malfunction with respect to the small flying bird or the like object may be avoided by setting the bsam projecting time to be relatively long, that is, to be longer than the passing time of the transitory small object, and also prolonging the beam reception and detection time. As will be readily understood, on the other hand, there still arise further problems that power consumption required for the beam projection becomes large, and that a use of, ~or example, an inexpensive light emitting diode as the bearn projecting e:Lement will resul-t in a poor durabl:Lity oE the apparatus due to easy deterioration of the diode in a shor-t time.
Fur-ther, there has been disclosed in Japanese Patent Appln. Laid-Open Publica-tion No.
120875/82 of S. Tutumi et al. a de-tection technique wherein a light projecting means including a plurality of relatively inexpensive ligh-t emitting diodes projects simultaneously a plurality of light beams, and a light receiving means also havina a plurality of light receiving diodes receives simultaneously reflected ones of the light beams with the receiving diodes corresponding to the emitting diodes of the reflected beams, so that a detection area corresponding to that of the projected light beams can be obtained.
In this case, the detection area can be of a certain expansion but it is still impossible to restrict the practical detection to a specific range within the area. Yet,the projection of the light beams is continuous during the use, so that the power consumption will become large and the inexpensive light emitting diodes will be fast deteriorated.
SU~MARY OF THE INVENTION
A primary object of the present invention is, therefore, to provide an object~detecting apparatus which is capable of restricting its de-tection area to a desired range, eliminating any malfunction with respect to a small flying animal or the like, 3~
employing :inexpensive l:Lght emitt:i.llg elements as L:ight projecting means Eor minimi~ lg recluired power consump-tion, and sti.ll. achieving a high rel:iab:ility and excel:lent economization.
Accorcling to the present invention, the ob-ject can be realized by providing an object detect:Lng apparatus of a restricted detection area, which comprises a p]ura-lity of light projecting means arranged in a row to be respectively independently actuated to project a row of light beams, scanning means for sequential actuation of the light projecting means at least in a plurality of groups, first means for receiving the :Light beams directly as projected from the respective light projecting means and not as refl.ected to return Erom a reflecting object, second means for receiving the light beams projected by the light projecting means and reflected by the reflecting object, means for receiving an output of the first light receiving means to provide a reference phase for the light beams projected, means for receiving an output of the second light receiving means to provide a detection phase for the light beams reflected and received~ means for determining a phase difference between the reference and detection phases, an alarm means operated by an output provided by the phase difference determining means, and area restricting means for restraining the output provi-sion of the phase difference determining means to the alarm means when the phase difference is of a level not within a pre-determined range.
Other objects and advantages of the present in-vention shall become clear from the following description of the invention detailed with reference to preEerred embodiments shown in the accompanying drawings.
BRIEF EXPLANATION OF THE DRAWINGS
.
FIGURE 1 shows schematically in a front elevation a relationship between the projection of the light beams and the reception of the reflected light beams by the light projecting means and second light receiving means in an embodiment of the present invention;
j:~
-- 6 ~
~2~.~3~
~IG. 2 shows also schematica:Lly :Ln a s:Lde eLeva-tion a relationship between the light beam projection and the reception by the :Eirst light receiving means in the embocliment of FIG. I;
FIG. 3 shows in detail to some extent an example of arrangement oF the :Light projecting ancl receiving means in FIG. 1 which includes light emitting elements ancl a light receiving element;
FIG. 4 shows in a front elevation a restricted detection area formed by the light projecting means of FIG. l;
Z~43~
FIG. 5 shows in a side elevation the detection area of FIG. 4;
FIG. 6 is a block diagram of an embodiment of a projected and received light signal p:rocessing means in the apparatus according to the present invention;
FIG. 7 is a detailed circuit diagram of the processing means in FIG. 6;
FIG. ~ shows waveforms of signals appearing at a part of the circuit of FIG. 6 or 7;
FIG. 9 is a circuit diagram in an embodiment oE the scanning means of the apparatus according to the present invention;
FIGS. 10 and 11 show waveforms of output signals o~ the scanning means of FIG. 9;
FIG. 12 shows schematically in a side elevation similar to FIG. 2 a relationship between the light projecting and receiving means in another embodiment of the apparatus according to the present invention;
FIG. 13 is a block diagra.m of another embodiment of the projected and re~eived light signal processing means used in the embodiment of FIG. 12;
FIG. 14 shows waveforms of output signals appearing a~ various points in the circuit o:E FIG.
13; and FIG. 15 is a circuit diagram oE another embodiment of an amplifier in the circuit of FIG. 6 or 7.
While the present i.nvention sllall now be descxibed with re:Eerence to the preEerred embodirnenl:s shown in the drawings, it should be understood -that the inten-tion is not -to limit the invention only to the par-ticular embodiments shown but rather to cover all altera-tions, modifica-tions and equivalent arrange-ments possible wi-thin the scope of appended claims.
DISCLOSURE OF PREFE.RRED EMBODIMENTS
ReEerring to FIGS. 1 and 2, there is shown an object detec-ting apparatus according to the present invention and vertically installed against the ground face GF, which apparatus comprises a light projecting means 11 includinga light projec-ting array 12 of a plurality of light emitting diodes 121,..., and 12n arranged substantially in a row as shown, for e~ample, in FIG. 3 to project beams of light pulse-modulated to be of a burs-t wave and respectively in diEferent directions but lying in a single plane. Disposed in such optical path o~ the array 12 are a collimator lens 13 and a half mirror 14 tilted by a proper angle so -that light beams Ls emitted from the diodes of the array 12 will pass through the lens 13 and reach the mirror 14, where a part of the light beams LB
is reflected by the mirror 14 to be directed toward a first light receiving means 15, while the remainder beams are caused to pass through the mirror 14 and to be reflected by such a fixed reElecting body as the ground face GF as well as such an object SO to _ g _
2~3~
be sensed as a trespasser, the reflectecl beams beiny directed toward a second l:Lyht receiv:Lng means 16.
As the light beam projection is made in the present instance in the mutually different directions on the same plane as emitted through the lens 13 from the light emitting diodes 121,..., and 12n arranged in an array or, in other words, so as to form a sector shaped plane of the coll:imated light beams expanding at any desired anyle, it is possible that, as shown in FIGS. 4 and 5, the object detecting apparatus 10 of the present invention is installed on a bu.ilding BD above its window ~D so that a liyht projectiny zone having a desired ranye coveriny the entire area of the window WD as expanded in parallel thereto.
The first liyht receiving means 15 includes a condenser lens 17, a photodiode 18 and a mirror 19 for further reflecting the partial light beams LB
reflected by the half mirror 14 to guide them through the condenser lens 17 to the photodiode 18. On the other hand, the second liyht receiving means 16 includes a condensing lens 20 and a photodiode 21 arranged to receive through the lens 20 any light beam incident from the side of the ground face GE'. Accordingly, the photodiode 18 in the first light receiving means 15 can receive substantially directly the projected light beams LB withou~ any reflection from the ground face GF or the object SO to be detected, whereas the 10 ~
be sensed as a trespasser, the reflectecl beams beiny directed toward a second l:Lyht receiv:Lng means 16.
As the light beam projection is made in the present instance in the mutually different directions on the same plane as emitted through the lens 13 from the light emitting diodes 121,..., and 12n arranged in an array or, in other words, so as to form a sector shaped plane of the coll:imated light beams expanding at any desired anyle, it is possible that, as shown in FIGS. 4 and 5, the object detecting apparatus 10 of the present invention is installed on a bu.ilding BD above its window ~D so that a liyht projectiny zone having a desired ranye coveriny the entire area of the window WD as expanded in parallel thereto.
The first liyht receiving means 15 includes a condenser lens 17, a photodiode 18 and a mirror 19 for further reflecting the partial light beams LB
reflected by the half mirror 14 to guide them through the condenser lens 17 to the photodiode 18. On the other hand, the second liyht receiving means 16 includes a condensing lens 20 and a photodiode 21 arranged to receive through the lens 20 any light beam incident from the side of the ground face GE'. Accordingly, the photodiode 18 in the first light receiving means 15 can receive substantially directly the projected light beams LB withou~ any reflection from the ground face GF or the object SO to be detected, whereas the 10 ~
3~
photodiode 21 in the second ligh-t .receiving rneans 16 receives the reflec-ted light beams from the ground face GF or the object SO. Upon receipt oE such ligh-t beams, the photodiodes 18 and 21 generate elec-tric curren-t signals which are sent to such a projected and received light signal p.rocessing means as shown in FIG. 6 -to determine any phase difference between the both siynal.s, as will be explained next.
Referring to FIG. 6 and also to FIG. 7 showing details of the circuit arrangement of FI~. 6, - there is shown in the projected and received light signal processing means for the input signals to the first and second light receiving means 15 and 16 resulting from the light beam projection by the projecting means 11. This processing means comprises amplifiers 22 and 23 respectively connected to each of the photodiodes 18 and 21 for amplifying electric currents generated a~ the photodiodes 18 and 21 with substantially the same amplification factor, mixing circuits 2~ and 25 respectively connected to the amplifier 22 or 23 and to a common local oscillator 26 for optimumly frequency-converting the amplified outputs of the amplifiers to corresponding signals in response to input signals from the local oscillator 26, filters 27 and 28 respectively connected to the mixing circuit 2~ or 25 for filtering the frequency-converted signals, and wave shaping circuits 29 and 30 for receiving the filtered signals. Such a rectangular 3~
wave RP indicative oE a reference phase as shown in FIG. 8(a) is generated by the wave-shaping circuit 29, based on the signal of the photodiode 18 res~llting from the directly received light beams without any reflection by the objec-t -to be detected or -the like, while the other wave shap:ing circuit 30 generates such a rectangular wave DP indicative of a detection phase as shown in FIG~ 8(b) based on the signal of the photodiode 21 resulting from the reflected light beams from the object or the like.
The reference phase signal RP from the wave shapiny circuit 29 and the detection phase signal DP
from the other wave shaping circuit 30 are then supplied to a gate cixcuit 31, in which such a phase difference signal PDP as shown in FIG. 8(c) is generated to have a pulse width from a rise time of the reference phase signal RP to a rise time of the detection phase signal DP. To the gate circuit 31, clock signals are being provided from a clock generator 32 so that such a phase dif~erence clock signal PDCK as shown in FIG. 8(d) will be provi.ded at its output terminal during the pulse width of the phase difference signal PDP of FIG. 8(c). The clock signal PDCK from the gate circuit 31 of which pulse number indicates a phase difference between the reference and de-tection phase signals is supplied to a counter 33 for counting the pulse number, and an output of the counter is sent to a comparator 34 which also receives an output ~rom 3~
a de-tecti.on dlstance setting ci.rcuit 35 to compare it wi.th the counter ou-tput.
When, for example, -this coun-ter ou-tput corresponding to the phase difference is smaller than the output of the distance setting circuit 35, it indicates that the objec-t SO exists in the detection area and thus the compara-tor 34 generates an output to operate such an alarm device as a buzzer provided at the subsequent stage. In other words, by setting at the distance setting circuit 35 a value wi-th respect to each of the projected light beams so as to correspond to a distance between the installed position of the object detecting apparatus 10 and an edge portion o~
the window WD, a detection area of a restricted range can be provided and, only when an object to be detected intrudes into this restricted range, the alarm operation will be effected. The comparator 34 and distance setting circuit 35 may be provided either in separate circuits or, optimally, in an integral form o~ a computer CPU as shown in FIG. 7.
On the o-ther hand, the ga-te circuit 31 is also connected with a selector 36 which includes, as detailed in FIG. 9, such switching elements 361 to 36n as transistors corresponding in number to the light emitting diodes 121 to 12n of the light projecting array 12. The respective switching elements 361 to 36n are sequentially actuated at optimum time intervals, the gate circuit 31 is opened upon actua-tion of the ~L2~ L3~
respective switching elements 36l to 36n and the :Light emi.tting diodes 121 to 12rl respectively coup:Led to each of the switching elements 36.l to 36n are thereby caused to turn ON sequentially as shown in FIG. 10. In other words, a plurality of -the light beams are emitted sequentially from the projecting array 12 according to the present invention, respectively forming an angle with adjacent one of them as passed through the collima-tor lens 13 and half mirror 14 along the single plane, so that the se~uen-tiall~
projected light beams will form as a whole a planar detection area having a certain expansion. Since the phase difference is calculated for each of the light emitting diodes 121 to 12n and the detection distance for each light beam is restricted on the basis of the setting values at the distance setting circuit 35 as in the foregoing, the detection area restricted to a range just covering the window WD as shown in FIGS. 4 and 5 can be realized. When the light projecting array 12 is driven on a so-called scanning basis, the light emitting diodes 121 to 12n will be turned ON respectively separately for only a short time, so that the power consumption necessary for actuating these diodes can be remarkably reduced, the durability of the diodes can be remarkably improved, detecting operation can be realized in a very short time, and inexpensive diodes can be effectively utilized.
When it is detect,ed with the EoregoincJ
arrangement and during the actuation oE one of the light emitting diodes that an object has entered the detection area, the particular diode alone can be continuously turned ON. More particularly, the arrangement is made so that, in the case where, for example, only the light emitting diode 122 wi-thin the respec-tive diodes 121 to 12n has detected a presence of the object in one scanning cycle for all of the diodes, the input to the comparator 34 exceeds a reference output voltage CRV set in the comparator as shown in FIG. 11(b), upon which a signal for causing the diode 122 only to be continuously actuated is fed to the selector 36 which providing the scanning outputs to the light projecting array 12, whereby the selector is caused to stop the scanning cycle for all the light emitting diodes 121-12n but to keep only the particular diode 122 to be actuated as shown in FIG. 11(a). In this case, the alarm means connected to the comparator receives continuously such out,puts Erom the comparator as shown in FIG. 11(c~, in response to which the alarm means is operatively coupled to a gradually integrating means so that, when the integrated value in this means exceeds a threshold voltage SVV, the alarm means will perform its alarm operation as shown in FIG. 11(e). Such arrangement enables a positive prevention of malfunction of the alarm means caused due especially to such transitory ~lL22~3~
intrucling object as a smal:L f:Lyiny or movirlg animal which enters but qu:iclc:Ly l.eaves the detect:Lon area.
In other words, it is possible to effectively detect only such an object which remains present within the detec-tion area as a trespasser trying -to break or open the window WD of FIGS. 4 and 5 to intrude in-to the building. It will be easily appreciated that, when a person who enters the detection area for installation, maintenance or the like purpose or by error immediately leaves the area, the alarm means can be similarly prevented from being actuated.
In FIG. 12, there is shown ano-ther embodiment adapted to detect a time difference instead of the phase difference, in which a second light receiving means 116 includes a second half mirror 137 and a second mirror 138, while a first light receiving means 115 is similar to that of the embodiment of FIGS.
1 and 2, and the second light receiving means 116 is provided to receive the light beams LB which are passed through the first and second half mirrors 114 and 137 and reflec-ted back from the stationary reflecting body or any object to be detected to the second half mirror 137 and then to the mirror 138, such beams being directed through a condensing lens 25 120 to a photodiode 121. Reference signal for the projected light beams and detection signal for the received light beams due to the light incision on ` the photodiodes 118 and 121 are processed by such a - 16 ~
~L%~ 3S
projection and recept:Lon signal processing means as shown in FIG. l3, in which such time diEference signal PDP as in FIG. 14(c) be-tween the reference signal RP oE FIG. 1~(a) and the detec-tion signal DP of FIG. 1~(b) is obtained, and such a time difference clock signal PDCK as shown in FIG. 1~(e) is provided to a counter 133 from a ga-te circuit 131 receiving such a clock signal CK as in FIG. 1~(d).
For the scanning operation of a light projecting array 112, a clock generator may be u-tilized together with the selector as partly shown in FIG. 7, so that respective light emitting diodes of the array 112 will be turned ON in synchronism with the clock pulse generated by the clock generator. Other 1~ arrangements are similar to those of the foregoing embodiments. In FIGS. 12 and 13, the same constituent elemen-ts as those of the foregoing embodiments in FIGS. 1 and 2 and FIGS. 6 and 7 are denoted by the same reference numerals but added by 100. In addition, since the distance restriction is effected on the basis of the phase difference or time difference between the reference and detection phase signals in both of the foregoing embodiments, it is possible to remove such a risk that, as in the case of the conventional system for determining the distance on the basis oE the amount of reflected light, an object actually at a relatively long distance is erroneously judged as if the same is at a relatively short distance ~2~ 3~
specifically when the object shows a high reflec-ti.on factor.
In the present inventio:n, :Eurther, vari.ous design modification can be made. For example, -the reference phase signal has been referred to as being obtained through the mirror and condensing lens in the above embodiments, but the ligh-t beams projected.
from -the ligh-t emission diodes may be partly branched into an optical fiber coupled directly to -the pho-todiode of the first light.receiving means. Further, while the light emi-tting diodes of the light projec-ting array has been disclosed to be individually separately scanned, the diodes may be divided into groups so that two or more diodes forming each group will be simultaneously actuated, in which event the projected light beam upon each light projection of the array can be made wider so as to further shorten the time required for each scanning cycle. In the projected and received light signal processing circuit of FIG.
6 or 7, on the other hand, the received light signals are continuously applied through the first and second light receiving means to the amplifiers according to the scanning cycle, but this arrangement involves a risk of erroneous distance judgement due to that the bias of the amplifiers tends to vary with time to cause their amplification degree to be varied so that, in the event of an increased amplification degree of the both amplifiers, the output waveform distortion LA~`1, of the ampliflers is also caused to vary with time, whereby the outputs of the wave shaping circ-lits responsive to such outputs are made to change their du-ty ratio to render the phase difference no more correspond to its actual value. This risk may be avoided when, as shown in FIG. 15, capaci-tors C1 and C2 having rela-tively large capacities are connected to an amplifier 222 having a bias resistance therein and a time constant determined by the bias resistance and capacitors C1 and C2 is se-t to be sufficiently larger than the liyht emitting period as activated with the burst waves from the light emitting diodes, so that any variation in the bias value of the amplifiers can be made negligibly small, the value will be substantially constant, and the phase difference can be made to correspond to the actual value.
Further, the computer CPU shown in FIG. 7 may be provided with a function of calculating an average value of the reference and detection phase differences at intervals of, for example, N scanning cycles, so as to realize the distance judgement on the subse~uent phase difference as based on the average value as a reference. Usually, the received light signals resulting from the light beams reflected from the same ground face GF tend to vary and, when the distance restriction is performed depending on the set value of the detection distance setting circuit as based on the first obtained detection value of one ~ Z~D~3~;
oE th0 light emit-tiny diodes as a reference, the determined distance will also be subjected to a variation. When such average value as above is utilized as a reference and the value is renewed at the intervals of N scanning cycles, however, a highly accurate distance restriction can be realized.
Fur-thermore, a delay circuit may be inserted between the alarm means and the comparator receiving the reference and detection phase difference signal, so that the delay circuit will provide a time lag to the timing of the comparator output supply to the alarm means. In the absence of such delay circuit, the alarm means operates substantially instantaneously upon a presence of intruder in the detection area so that he may easily recognize the extent of the set detection area, but this risk can be removed by the time lag provided by the delay circuit to the operation of the alarm means. That is, the alarm means may be made notto operate immediately upon transitory insertion of the intruder's hand or the like into the set detection area but to operate after its removal from the area. When a second alarm means is provided as installed at an associated security service or the like in addition to the first alarm means, it is also useful to insert a delay circuit between the first and second alarm means. It is also possible in this case that, when an installing engineer or the like person mistakingly enters the detection area and the first ~z;2~3r~
alarm means has been thereby operated, the operation of the second alarm means can be avoided so lony as he quickly gets out oE the detec-tion area.
In addition, such light emittirlg elements that can emit visible lights may be additionally provided in the light projecting array, ~or use only upon installation of the object detecting apparatus, so that he may be able -to check.the location of the intended detec-tion area with the visible lights.
photodiode 21 in the second ligh-t .receiving rneans 16 receives the reflec-ted light beams from the ground face GF or the object SO. Upon receipt oE such ligh-t beams, the photodiodes 18 and 21 generate elec-tric curren-t signals which are sent to such a projected and received light signal p.rocessing means as shown in FIG. 6 -to determine any phase difference between the both siynal.s, as will be explained next.
Referring to FIG. 6 and also to FIG. 7 showing details of the circuit arrangement of FI~. 6, - there is shown in the projected and received light signal processing means for the input signals to the first and second light receiving means 15 and 16 resulting from the light beam projection by the projecting means 11. This processing means comprises amplifiers 22 and 23 respectively connected to each of the photodiodes 18 and 21 for amplifying electric currents generated a~ the photodiodes 18 and 21 with substantially the same amplification factor, mixing circuits 2~ and 25 respectively connected to the amplifier 22 or 23 and to a common local oscillator 26 for optimumly frequency-converting the amplified outputs of the amplifiers to corresponding signals in response to input signals from the local oscillator 26, filters 27 and 28 respectively connected to the mixing circuit 2~ or 25 for filtering the frequency-converted signals, and wave shaping circuits 29 and 30 for receiving the filtered signals. Such a rectangular 3~
wave RP indicative oE a reference phase as shown in FIG. 8(a) is generated by the wave-shaping circuit 29, based on the signal of the photodiode 18 res~llting from the directly received light beams without any reflection by the objec-t -to be detected or -the like, while the other wave shap:ing circuit 30 generates such a rectangular wave DP indicative of a detection phase as shown in FIG~ 8(b) based on the signal of the photodiode 21 resulting from the reflected light beams from the object or the like.
The reference phase signal RP from the wave shapiny circuit 29 and the detection phase signal DP
from the other wave shaping circuit 30 are then supplied to a gate cixcuit 31, in which such a phase difference signal PDP as shown in FIG. 8(c) is generated to have a pulse width from a rise time of the reference phase signal RP to a rise time of the detection phase signal DP. To the gate circuit 31, clock signals are being provided from a clock generator 32 so that such a phase dif~erence clock signal PDCK as shown in FIG. 8(d) will be provi.ded at its output terminal during the pulse width of the phase difference signal PDP of FIG. 8(c). The clock signal PDCK from the gate circuit 31 of which pulse number indicates a phase difference between the reference and de-tection phase signals is supplied to a counter 33 for counting the pulse number, and an output of the counter is sent to a comparator 34 which also receives an output ~rom 3~
a de-tecti.on dlstance setting ci.rcuit 35 to compare it wi.th the counter ou-tput.
When, for example, -this coun-ter ou-tput corresponding to the phase difference is smaller than the output of the distance setting circuit 35, it indicates that the objec-t SO exists in the detection area and thus the compara-tor 34 generates an output to operate such an alarm device as a buzzer provided at the subsequent stage. In other words, by setting at the distance setting circuit 35 a value wi-th respect to each of the projected light beams so as to correspond to a distance between the installed position of the object detecting apparatus 10 and an edge portion o~
the window WD, a detection area of a restricted range can be provided and, only when an object to be detected intrudes into this restricted range, the alarm operation will be effected. The comparator 34 and distance setting circuit 35 may be provided either in separate circuits or, optimally, in an integral form o~ a computer CPU as shown in FIG. 7.
On the o-ther hand, the ga-te circuit 31 is also connected with a selector 36 which includes, as detailed in FIG. 9, such switching elements 361 to 36n as transistors corresponding in number to the light emitting diodes 121 to 12n of the light projecting array 12. The respective switching elements 361 to 36n are sequentially actuated at optimum time intervals, the gate circuit 31 is opened upon actua-tion of the ~L2~ L3~
respective switching elements 36l to 36n and the :Light emi.tting diodes 121 to 12rl respectively coup:Led to each of the switching elements 36.l to 36n are thereby caused to turn ON sequentially as shown in FIG. 10. In other words, a plurality of -the light beams are emitted sequentially from the projecting array 12 according to the present invention, respectively forming an angle with adjacent one of them as passed through the collima-tor lens 13 and half mirror 14 along the single plane, so that the se~uen-tiall~
projected light beams will form as a whole a planar detection area having a certain expansion. Since the phase difference is calculated for each of the light emitting diodes 121 to 12n and the detection distance for each light beam is restricted on the basis of the setting values at the distance setting circuit 35 as in the foregoing, the detection area restricted to a range just covering the window WD as shown in FIGS. 4 and 5 can be realized. When the light projecting array 12 is driven on a so-called scanning basis, the light emitting diodes 121 to 12n will be turned ON respectively separately for only a short time, so that the power consumption necessary for actuating these diodes can be remarkably reduced, the durability of the diodes can be remarkably improved, detecting operation can be realized in a very short time, and inexpensive diodes can be effectively utilized.
When it is detect,ed with the EoregoincJ
arrangement and during the actuation oE one of the light emitting diodes that an object has entered the detection area, the particular diode alone can be continuously turned ON. More particularly, the arrangement is made so that, in the case where, for example, only the light emitting diode 122 wi-thin the respec-tive diodes 121 to 12n has detected a presence of the object in one scanning cycle for all of the diodes, the input to the comparator 34 exceeds a reference output voltage CRV set in the comparator as shown in FIG. 11(b), upon which a signal for causing the diode 122 only to be continuously actuated is fed to the selector 36 which providing the scanning outputs to the light projecting array 12, whereby the selector is caused to stop the scanning cycle for all the light emitting diodes 121-12n but to keep only the particular diode 122 to be actuated as shown in FIG. 11(a). In this case, the alarm means connected to the comparator receives continuously such out,puts Erom the comparator as shown in FIG. 11(c~, in response to which the alarm means is operatively coupled to a gradually integrating means so that, when the integrated value in this means exceeds a threshold voltage SVV, the alarm means will perform its alarm operation as shown in FIG. 11(e). Such arrangement enables a positive prevention of malfunction of the alarm means caused due especially to such transitory ~lL22~3~
intrucling object as a smal:L f:Lyiny or movirlg animal which enters but qu:iclc:Ly l.eaves the detect:Lon area.
In other words, it is possible to effectively detect only such an object which remains present within the detec-tion area as a trespasser trying -to break or open the window WD of FIGS. 4 and 5 to intrude in-to the building. It will be easily appreciated that, when a person who enters the detection area for installation, maintenance or the like purpose or by error immediately leaves the area, the alarm means can be similarly prevented from being actuated.
In FIG. 12, there is shown ano-ther embodiment adapted to detect a time difference instead of the phase difference, in which a second light receiving means 116 includes a second half mirror 137 and a second mirror 138, while a first light receiving means 115 is similar to that of the embodiment of FIGS.
1 and 2, and the second light receiving means 116 is provided to receive the light beams LB which are passed through the first and second half mirrors 114 and 137 and reflec-ted back from the stationary reflecting body or any object to be detected to the second half mirror 137 and then to the mirror 138, such beams being directed through a condensing lens 25 120 to a photodiode 121. Reference signal for the projected light beams and detection signal for the received light beams due to the light incision on ` the photodiodes 118 and 121 are processed by such a - 16 ~
~L%~ 3S
projection and recept:Lon signal processing means as shown in FIG. l3, in which such time diEference signal PDP as in FIG. 14(c) be-tween the reference signal RP oE FIG. 1~(a) and the detec-tion signal DP of FIG. 1~(b) is obtained, and such a time difference clock signal PDCK as shown in FIG. 1~(e) is provided to a counter 133 from a ga-te circuit 131 receiving such a clock signal CK as in FIG. 1~(d).
For the scanning operation of a light projecting array 112, a clock generator may be u-tilized together with the selector as partly shown in FIG. 7, so that respective light emitting diodes of the array 112 will be turned ON in synchronism with the clock pulse generated by the clock generator. Other 1~ arrangements are similar to those of the foregoing embodiments. In FIGS. 12 and 13, the same constituent elemen-ts as those of the foregoing embodiments in FIGS. 1 and 2 and FIGS. 6 and 7 are denoted by the same reference numerals but added by 100. In addition, since the distance restriction is effected on the basis of the phase difference or time difference between the reference and detection phase signals in both of the foregoing embodiments, it is possible to remove such a risk that, as in the case of the conventional system for determining the distance on the basis oE the amount of reflected light, an object actually at a relatively long distance is erroneously judged as if the same is at a relatively short distance ~2~ 3~
specifically when the object shows a high reflec-ti.on factor.
In the present inventio:n, :Eurther, vari.ous design modification can be made. For example, -the reference phase signal has been referred to as being obtained through the mirror and condensing lens in the above embodiments, but the ligh-t beams projected.
from -the ligh-t emission diodes may be partly branched into an optical fiber coupled directly to -the pho-todiode of the first light.receiving means. Further, while the light emi-tting diodes of the light projec-ting array has been disclosed to be individually separately scanned, the diodes may be divided into groups so that two or more diodes forming each group will be simultaneously actuated, in which event the projected light beam upon each light projection of the array can be made wider so as to further shorten the time required for each scanning cycle. In the projected and received light signal processing circuit of FIG.
6 or 7, on the other hand, the received light signals are continuously applied through the first and second light receiving means to the amplifiers according to the scanning cycle, but this arrangement involves a risk of erroneous distance judgement due to that the bias of the amplifiers tends to vary with time to cause their amplification degree to be varied so that, in the event of an increased amplification degree of the both amplifiers, the output waveform distortion LA~`1, of the ampliflers is also caused to vary with time, whereby the outputs of the wave shaping circ-lits responsive to such outputs are made to change their du-ty ratio to render the phase difference no more correspond to its actual value. This risk may be avoided when, as shown in FIG. 15, capaci-tors C1 and C2 having rela-tively large capacities are connected to an amplifier 222 having a bias resistance therein and a time constant determined by the bias resistance and capacitors C1 and C2 is se-t to be sufficiently larger than the liyht emitting period as activated with the burst waves from the light emitting diodes, so that any variation in the bias value of the amplifiers can be made negligibly small, the value will be substantially constant, and the phase difference can be made to correspond to the actual value.
Further, the computer CPU shown in FIG. 7 may be provided with a function of calculating an average value of the reference and detection phase differences at intervals of, for example, N scanning cycles, so as to realize the distance judgement on the subse~uent phase difference as based on the average value as a reference. Usually, the received light signals resulting from the light beams reflected from the same ground face GF tend to vary and, when the distance restriction is performed depending on the set value of the detection distance setting circuit as based on the first obtained detection value of one ~ Z~D~3~;
oE th0 light emit-tiny diodes as a reference, the determined distance will also be subjected to a variation. When such average value as above is utilized as a reference and the value is renewed at the intervals of N scanning cycles, however, a highly accurate distance restriction can be realized.
Fur-thermore, a delay circuit may be inserted between the alarm means and the comparator receiving the reference and detection phase difference signal, so that the delay circuit will provide a time lag to the timing of the comparator output supply to the alarm means. In the absence of such delay circuit, the alarm means operates substantially instantaneously upon a presence of intruder in the detection area so that he may easily recognize the extent of the set detection area, but this risk can be removed by the time lag provided by the delay circuit to the operation of the alarm means. That is, the alarm means may be made notto operate immediately upon transitory insertion of the intruder's hand or the like into the set detection area but to operate after its removal from the area. When a second alarm means is provided as installed at an associated security service or the like in addition to the first alarm means, it is also useful to insert a delay circuit between the first and second alarm means. It is also possible in this case that, when an installing engineer or the like person mistakingly enters the detection area and the first ~z;2~3r~
alarm means has been thereby operated, the operation of the second alarm means can be avoided so lony as he quickly gets out oE the detec-tion area.
In addition, such light emittirlg elements that can emit visible lights may be additionally provided in the light projecting array, ~or use only upon installation of the object detecting apparatus, so that he may be able -to check.the location of the intended detec-tion area with the visible lights.
Claims (8)
1. An object detecting apparatus of a restricted detection area, which comprises a plurality of light projecting means arranged in a row to be respectively independently actuated to project a row of light beams, scanning means for sequential actuation of said light projecting means at least in a plurality of groups, first means for receiving said light beams directly as projected from the respective light projecting means and not as reflected to return from a reflecting object, second means for receiving the light beams projected by the light projecting means and reflected by said reflecting object, means for receiving an output of said first light receiving means to provide a reference phase for the light beams projected, means for receiving an output of said second light receiving means to provide a detection phase for the light beams reflected and received, means for determining a phase difference between said reference and detection phases, an alarm means operated by an output provided by said phase difference determining means, and area restricting means for restraining said output provision of the phase difference determining means to said alarm means when said phase difference is of a level not within a predetermined range.
2. An object detecting apparatus according to claim 1, wherein respective said light projecting means are light emitting elements actuatable with a low current and arranged in a light projecting array, respective said light beams being projected from said light projecting array to form as a whole an angled range lying on a single plane.
3. An object detecting apparatus according to claim 2, which further comprises means for continuously actuating only a part of said light emitting elements corresponding to said reflected light beams received.
4. An object detecting apparatus according to claim 1, wherein said phase difference determining means comprises a comparator which receives said output of said phase difference determining means, and the apparatus further comprises a detection distance setting circuit connected to said comparator to provide thereto a predetermined set value.
5. An object detecting apparatus according to claim 1, which further comprises means connected to said phase difference determining means for obtaining an average value of said phase difference at intervals of N scanning cycles of respective said light projecting means by said scanning means, said average value being used for determining subsequent ones of the phase difference.
6. An object detecting apparatus according to claim 1, which further comprises first delay means inserted between said phase difference determining means and said alarm means for delaying said output of the phase difference determining means.
7. An object detecting apparatus according to claim 1, wherein said alarm means comprises first and second alarm means which are operated sequentially, and a delay means inserted between said first and second alarm means.
8. An object detecting apparatus according to claim 1, wherein said plurality of light projecting means partly comprises visible light emitting elements for use upon installation of said apparatus.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP83143/1984 | 1984-04-25 | ||
| JP59083143A JPS60227185A (en) | 1984-04-25 | 1984-04-25 | Optical range measurement type body detecting device |
| JP213408/1984 | 1984-10-12 | ||
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|---|---|
| CA1221435A true CA1221435A (en) | 1987-05-05 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000479069A Expired CA1221435A (en) | 1984-04-25 | 1985-04-12 | Object detecting apparatus including photosensors for restricted detection area |
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| US (1) | US4656462A (en) |
| CA (1) | CA1221435A (en) |
| DE (1) | DE3514982A1 (en) |
| FR (1) | FR2563646B1 (en) |
| GB (1) | GB2158232B (en) |
| IT (1) | IT1182032B (en) |
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|---|---|---|---|---|
| DE2014681C2 (en) * | 1970-03-26 | 1978-09-07 | Texas Instruments Deutschland Gmbh, 8050 Freising | Distance measuring device with HF light modulation and IF phase comparison |
| US3727207A (en) * | 1970-06-24 | 1973-04-10 | Systron Donner Corp | Intrusion detector |
| US3752978A (en) * | 1971-02-04 | 1973-08-14 | Arrowhead Ets Inc | Photoelectric intrusion detector |
| US3723738A (en) * | 1971-05-20 | 1973-03-27 | Motorola Inc | Intrusion detection false alarm reduction system |
| DE2452794C3 (en) * | 1974-11-07 | 1979-08-30 | Philips Patentverwaltung Gmbh, 2000 Hamburg | Automatic level adjustment circuit for presettable IR pulse monitoring devices with clocked receiver |
| US4103285A (en) * | 1976-12-07 | 1978-07-25 | William Lloyd | Vehicle anti-theft alarm system |
| DE2851444C2 (en) * | 1978-11-28 | 1983-05-26 | Erwin Sick Gmbh Optik-Elektronik, 7808 Waldkirch | Light curtain |
| JPS57120875A (en) * | 1981-01-19 | 1982-07-28 | Suteo Tsutsumi | Method for monitoring rear of vehicle |
| US4479053A (en) * | 1981-03-11 | 1984-10-23 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Focal plane array optical proximity sensor |
-
1985
- 1985-04-10 GB GB08509182A patent/GB2158232B/en not_active Expired
- 1985-04-12 CA CA000479069A patent/CA1221435A/en not_active Expired
- 1985-04-15 US US06/723,060 patent/US4656462A/en not_active Expired - Fee Related
- 1985-04-22 IT IT47985/85A patent/IT1182032B/en active
- 1985-04-24 FR FR858506274A patent/FR2563646B1/en not_active Expired
- 1985-04-25 DE DE19853514982 patent/DE3514982A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| FR2563646A1 (en) | 1985-10-31 |
| DE3514982A1 (en) | 1985-10-31 |
| GB2158232A (en) | 1985-11-06 |
| IT8547985A0 (en) | 1985-04-22 |
| GB8509182D0 (en) | 1985-05-15 |
| IT1182032B (en) | 1987-09-30 |
| FR2563646B1 (en) | 1989-05-05 |
| DE3514982C2 (en) | 1989-04-06 |
| US4656462A (en) | 1987-04-07 |
| GB2158232B (en) | 1987-11-18 |
| IT8547985A1 (en) | 1986-10-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |