WO1987005115A1 - Detecteur optique passif - Google Patents

Detecteur optique passif Download PDF

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Publication number
WO1987005115A1
WO1987005115A1 PCT/SE1987/000094 SE8700094W WO8705115A1 WO 1987005115 A1 WO1987005115 A1 WO 1987005115A1 SE 8700094 W SE8700094 W SE 8700094W WO 8705115 A1 WO8705115 A1 WO 8705115A1
Authority
WO
WIPO (PCT)
Prior art keywords
optical detector
output
photocell
amplifier
circuit
Prior art date
Application number
PCT/SE1987/000094
Other languages
English (en)
Inventor
Robert Andersson
Bo Strandman
Morgan Fagerman
Original Assignee
Silvergranen Innovation Ab
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Priority claimed from SE8600847A external-priority patent/SE8600847D0/xx
Application filed by Silvergranen Innovation Ab filed Critical Silvergranen Innovation Ab
Publication of WO1987005115A1 publication Critical patent/WO1987005115A1/fr

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
    • G01P13/00—Indicating or recording presence, absence, or direction, of movement
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V8/00—Prospecting or detecting by optical means
    • G01V8/10—Detecting, e.g. by using light barriers

Definitions

  • the present invention relates to an optical detector of the kind disclosed in the preamble to the following claim 1.
  • the mentioned optical detectors may be used for providing optical detection of a movement, e.g. in connection with goods on a conveyor belt, escalator, shop doorway, detection of movement at a large distance, indication of movement velocity etc. Disclosure of Invention
  • the present invention has, inter alia, the task of eliminating or mitigating the disadvantages with known optical detectors. It further has the task of providing a detector of the kind mentioned in the introduction that is not sensitive to vibration, that has a long life, that allows easy installation and that covers long distances.
  • the inventive optical detector is intended to replace apparatus of the type operating with a specially illuminated photocell, where the objects to be detected interrupt the emitted light beam between source and photocell.
  • the inventive ' principle is based on the realisation that much better reliability and great simplification are achieved if the special light source can be dispensed with. Accordingly, the invention utilises prevailing light, daylight, indoor illumination or other existing, ambient light. This simplifies the structural implementation of the thus passive optical detector, and eliminates the need of service and adjustment.
  • photocell is used hereinafter for such light-sensitive elements, both in the description and claims.
  • the two photocells are mutually directed towards a far distance target. Both photocells are electrically connected in series, and the photo detector signals are taken off at the connection between the photocells, either directly or via capacitors or resistors, to an input on a signal processing circuit having a zero-pass amplifier which, through a signal formation step is activating a relay circuit coupled to relay means or the like.
  • the zero-pass amplifier may include a branch circuit for the respective photocell being associated to an amplifier.
  • the signal formation step in the respective branch circuit comprises a Schmitt trigger or the like, and after inverting the signal from one of the triggers their output signals are applied to an OR gate included in the relay control circuit.
  • the output of the OR gate is connected to • a relay means or the like, which in turn provides the necessary operational indication or control, although this is not a subject of the invention.
  • Figure 1 is a wiring diagram for a passive optical detector in accordance with the invention and with resistance-changing light-sensitive elements.
  • Figure 2 is a wiring diagram of a modified embodiment.
  • Figure 3 is a diagram of a Schmitt trigger.
  • Figure 4 illustrates another input to the circuit with current generating light-sensitive cells and
  • Figure 5 illustrates an embodiment of the invention where a plurality of photocell pairs is used for monitoring an extensive area.
  • the circuit 100 includes a zero-pass amplifier 106 and a signal formation step 107.
  • the circuit 100 also includes a branch circuit 41 - 71 and 42 - 72, for the respective photocell 11, 12.
  • the amplifier 106 then includes two branches, each with its respective capacitor 41, 42 or resistor 51, 52 connected to an amplifier 61, 62. With the aid of the capacitors or resistors the amplifiers are balanced such that the amplifier of one branch amplifies a voltage variation tending towards plus, while the other amplifies a voltage variation tending towards minus.
  • the signal formation step 107 is" connected after the amplifiers 61, 62 and is provided with a Schmitt trigger 71, 72 for the respective branch, the signal from one of the triggers being inverted, so that the output signals have the same polarity. This may be accomplished either by one of the amplifiers having an inverting output or by an inverting means 2 being connected after one of them.
  • the outputs of both triggers 71 , 72 are connected to each the input on an OR gate 3.
  • the OR gate will thus give a signal only if there is a difference in the amount of light incident on one of the photocells as compared with that incident on the other photocell.
  • the time during which the difference must be present for a detection signal to be sent can be easily modified by suitable dimensioning of the capacitors 41, 42 or resistors 51, 52.
  • a resistor 31 , 32 may be arranged in parallel with the photocells in Figure 2 for the purpose of stabilisation. These resistors are suitably high- oh ic, in the megaohm order of magnitude.
  • the output of the OR gate 3 is connected e.g.
  • a further Schmitt trigger 5 can be arranged between the OR gate 3 and the relay means 4, as in Figure 2.
  • the inventive optical detector is intended to be driven by batteries or the like, and if CMOS electronics are used the current consumption will be very low, i.e. in the order of magnitude of some microamperes, thus affording very long battery life.
  • FIG 3 is a Schmitt trigger diagram, the triggering point being denoted by T.
  • An associated "•amplifier is turned such that both its positions FI and FII are respectively distinctly to the right and left of the trigger point T, thus providing reliable triggering on going from FI to FII.
  • the moving outputs of the resistors are connected to the input of the respective amplifier 61, 62.
  • a single tuning resistor 8 may be connected the positive input of one amplifier and the negative input of the other, the mentioned in ⁇ puts of both amplifiers then being connected to the supply plus or minus potential via respective fixed resistors.
  • the change is propagated via the capacitors 41, 42, amplifiers 61, 62 and trigger circuits 71, 72 to both inputs of the OR gate 3, one of these being given a signal, whereby the OR condition is met, and the output of the OR gate sends a signal to the relay 4 to trigger it.
  • the wiring diagrams illustrated on the draw ⁇ ing as examples can be modified further by one skilled in the art with measures known per se. Accordingly, indication can be achieved showing whether beam I or beam II is interrupted first, and whether the interrupting object is lighter or darker than the point P, thus enabling, indication of direction. It is also possible to select or adjust the brightness of points P, P' as desired in one or other respect. Furthermore, it is possible to improve and/or adjust reaction sensitivity by suitable selection of components.
  • the optical detector in accordance with the invention uses the light available on site and adjusts itself to the light conditions prevailing at the indicating instant. Since the light may vary, seen as a whole, the inventive optical detector functions just as well in weak as in strong light. It is practically completely insensitive to light variations at the points P.
  • the present invention uses photocells 11, 12 coupled in pairs, which have their incident light paths, mutually parallel or arranged at a mutual acute angle, thus signifying that one photocell can continuously receive a stronger light while the other photocell can continuously receive a weak light, there is achieved by the invention the essential difference that the optical detector solely detects the difference in signals from both photo ⁇ cells, i.e. whether one of them suddenly receives a definitely less amount of light .compared with the other one. Practical trials have also shown that signal differences within such short times as a few milliseconds are quite sufficient to enable the optical detector to send an operating signal.
  • the inventive optical detector adjusts itself to prevailing light conditions, it is excellen for detecting objects or movements at large distances when associated with suitable optical means.
  • optical means are well known in the prior art and are not part of the invention, since they can be provided by one skilled in the art within the scope of his competence. He can also easily modify the inventive optical detector to enable it to indicate the speed of an obje ' ct detected by it, thus turning it into a movement detector and the indication of the movement direction to or from can also be enabled in a conventional manner. The speed of the reaction is solely dependent on photo ⁇ cell sensitivity.
  • FIG. 5 A further development of the passive optical detector in accordance with the invention is illustrated in Figure 5, and is intended for sensing moving objects over a large area. More specifically, this detector may be used for indicating that only one person at a time is within a certain area.
  • This further developed indicator thus includes a plurality of pairs of photocells 11 - 12 (64 such pairs 11 - 12 being shown in the Figure) uniformly distributed over the area to be monitored.
  • the photo ⁇ cells can be arranged in a roof over the area, the roof taking the form of one with a flat surface provided with a duct for each photocell 11, 12, of which there are 128 in this case.
  • the signals from the photocell pairs 11 - 12 are sampled periodically, and the sampling is regulated by a switching circuit 102 controlled by a clock circuit 103.
  • the signal from a sampled photocell pair 11 - 12 is taken to a data collection circuit 101, which feeds an input 10 on a signal processing circuit 100.
  • a memory circuit 104 is connected to the output of the signal processing circuit 100 for evaluating each signal message from it.
  • the quantity circuit 105 There are two outputs on the quantity circuit 105, the upper output in Figure 5 is intended to signal the state "more than one person” and the lower output the state "more than two persons" are within the monitored area.
  • the quantity circuit 105 may be setable for the desired quantity of objects/persons it is desired to monitor.
  • the circuit wiring for data collection and evaluation is made up from electronic integrated circuits.
  • IC1 - IC11 represent 8-bit analog MUX/DEMUX's, IC12 and IC18 8-bit NAND gates, IC13 and IC16 so-called ripple counters (seven bits, CD 4024) , IC14 amplifiers of type 324, IC19 and IC20 OR gates, IC15 a NAND gate of quadruple type with double inputs, both having a Schmitt trigger, and IC17 a memory with 2 x 4 bits.
  • Moving objects/persons may thus be sensed in a given area by the optical detector accordring to Figure 5.
  • the area may be a room or a corridor provided with a door which, on its being opened can cause a resetting signal RES to the detector, so that opening the door causes detection to start from an initial state.
  • RES resetting signal
  • the inventive optical detector is entirely insensitive to the light variations which may exist at the site monitored. Accordingly, the effects of sun or shadow in cloudy weather or the illumination from lighting do not deleteriously affect the signals from the detector.
  • the radiation sensed by the photocells may be given a desired configuration with the aid of suitable auxiliary means.
  • the inventive detector can be made without being sensitive to vibration and it can be optically robust.
  • very cheap electronics can be used to realise the invention, enabling the detector to be marketed at a low price.
  • the signal processing circuit 100 can have its zero-pass amplifier 106 and signal formation step 107 each implemented as an EXCLUSIVE-OR gate which, via a relay control circuit including a further EXCLUSIVE-OR gate, activates a transistor, which thus f nctions as the mentioned relay 4.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Geophysics (AREA)
  • Geophysics And Detection Of Objects (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)

Abstract

Un détecteur optique passif possède des cellules photoélectriques qui permettent une détection optique en utilisant uniquement la lumière ambiante existante, par exemple la lumière du jour ou l'éclairage normal d'un espace. Le détecteur optique ci-décrit comporte deux cellules photoélectriques passives (11, 12) couplées en série avec une sortie centrale (1) située entre les deux. Les cellules photoélectriques sont agencées de telle manière que les trajectroires respectives de leurs rayons incidents sont soit mutuellement parallèles soit convergentes. Un trigger de Schmitt (71, 72) est disposé en aval d'un amplificateur (61, 62) connecté à chaque cellule photoélectrique (11, 12), les sorties des triggers (71, 72) sont connectées à leurs entrées respectives sur une porte OU (3) dont la sortie est connectée au relais (4).
PCT/SE1987/000094 1986-02-25 1987-02-25 Detecteur optique passif WO1987005115A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
SE8600847-1 1986-02-25
SE8600847A SE8600847D0 (sv) 1986-02-25 1986-02-25 Optisk detektor
SE8603335A SE452068B (sv) 1986-02-25 1986-08-06 Passiv optisk detektor
SE8603335-4 1986-08-06

Publications (1)

Publication Number Publication Date
WO1987005115A1 true WO1987005115A1 (fr) 1987-08-27

Family

ID=26659261

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1987/000094 WO1987005115A1 (fr) 1986-02-25 1987-02-25 Detecteur optique passif

Country Status (3)

Country Link
CN (1) CN87101582A (fr)
AU (1) AU7035387A (fr)
WO (1) WO1987005115A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0617290A1 (fr) * 1993-03-20 1994-09-28 ABBPATENT GmbH Commutateur activé par un capteur de mouvement
DE19504606A1 (de) * 1995-02-11 1996-08-14 Kostal Leopold Gmbh & Co Kg Optoelektronische Einrichtung

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111121965A (zh) * 2019-12-24 2020-05-08 南京理工大学 宽动态范围的紫外辐射照度计

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3444384A (en) * 1966-11-07 1969-05-13 Geza E Horeczky Motion selector using ratio of responses of two photoelectric cells

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3444384A (en) * 1966-11-07 1969-05-13 Geza E Horeczky Motion selector using ratio of responses of two photoelectric cells

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0617290A1 (fr) * 1993-03-20 1994-09-28 ABBPATENT GmbH Commutateur activé par un capteur de mouvement
DE19504606A1 (de) * 1995-02-11 1996-08-14 Kostal Leopold Gmbh & Co Kg Optoelektronische Einrichtung
DE19504606C2 (de) * 1995-02-11 1999-01-07 Kostal Leopold Gmbh & Co Kg Optoelektronische Einrichtung zur Erfassung von auf der Außenseite einer transparenten Scheibe sich ablagerndem Niederschlag

Also Published As

Publication number Publication date
AU7035387A (en) 1987-09-09
CN87101582A (zh) 1987-09-30

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