EP0588073A1 - Capteur pyroélectrique pour détecteurs infrarouges et passifs de mouvement - Google Patents

Capteur pyroélectrique pour détecteurs infrarouges et passifs de mouvement Download PDF

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Publication number
EP0588073A1
EP0588073A1 EP93113077A EP93113077A EP0588073A1 EP 0588073 A1 EP0588073 A1 EP 0588073A1 EP 93113077 A EP93113077 A EP 93113077A EP 93113077 A EP93113077 A EP 93113077A EP 0588073 A1 EP0588073 A1 EP 0588073A1
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EP
European Patent Office
Prior art keywords
silicon
plate
pyroelectric
layer
infrared
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.)
Withdrawn
Application number
EP93113077A
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German (de)
English (en)
Inventor
Martin Forster
Peter Ryser
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Cerberus AG
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Cerberus AG
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Filing date
Publication date
Application filed by Cerberus AG filed Critical Cerberus AG
Publication of EP0588073A1 publication Critical patent/EP0588073A1/fr
Withdrawn legal-status Critical Current

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    • 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
    • G08B13/189—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems
    • G08B13/19—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using infrared-radiation detection systems
    • G08B13/193—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using passive radiation detection systems using infrared-radiation detection systems using focusing means

Definitions

  • the invention relates to a pyroelectric sensor for passive infrared motion detectors according to the preamble of claim 1 and a method for producing such a pyroelectric sensor.
  • Passive infrared motion detectors are generally known, they are used to detect moving objects emitting infrared radiation, for example in systems for monitoring rooms.
  • the infrared motion detectors have an optical system (mirror or lens) arranged in front of the sensor in the radiation direction for focusing the radiation arriving from the area to be monitored on the sensor and an electronic evaluation circuit.
  • an optical system mirror or lens
  • the pyroelectric radiation sensors used consist of pyroelectric materials with electrodes arranged on opposite surfaces.
  • platelets made of lithium tantalate or lead zirconate titanate (PZT) or foils made of polyvinylidene difluoride (PVDF) ground to thin layers serve as pyroelectric materials.
  • the sensor elements form capacitors which generally have a capacitance of approximately 10 pF.
  • the infrared radiation that occurs when an object whose temperature differs from the temperature of the surroundings enters a room to be monitored is directed through a focusing optic (mirror or lens) to the radiation receiver arranged at or near the focal point of the optics. It has proven to be particularly advantageous if the optics is divided into separate elements in such a way that the space to be monitored is divided into discrete sensitivity areas (monitoring areas), as was proposed in US-A1-3,703,718.
  • Infrared motion detectors of the type described are disclosed, for example, in CA-A-1'261'941, EP-A1-0'218'055 and EP-A2-0'209'385.
  • a disadvantage of these systems is that the length of the infrared motion detectors - due to the length of the focal lengths of the mirrors or lenses - is quite large.
  • Another disadvantage is that they consist of several parts (e.g. mirror optics, Fresnel lenses, sensors, printed circuit boards) that have to be coordinated (adjusted) with one another. This causes a complicated manufacture of the infrared motion detectors and a minimum size cannot be undershot.
  • Infrared motion detectors are so widely used today that their mass production is inevitable; this presupposes that the production is not made as a one-off, but that a large number can be produced together in one work step (batchwise production).
  • WO-88/04038 describes a pyroelectric motion detector in which the active area is a round cylinder.
  • the disadvantage of the sensor described there is that it cannot be manufactured on silicon and is not suitable for mass production.
  • EP-A1-0'347'704 describes a pyroelectric sensor which is constructed from sheet metal parts overmolded with epoxy resin. It does not contain a lens for zone mapping and can only be mass-produced in one dimension. In addition, it has insufficient protection against electrostatic fields and against moisture.
  • the object of the invention is to avoid the disadvantages of the pyroelectric sensors used previously for passive infrared motion detectors and, in particular, to create those pyroelectric sensors which enable simplified production, in particular batchwise production, and which are small and precise are.
  • the infrared filter is located above an opening arranged in a silicon plate for the passage of infrared radiation;
  • a lead-zirconate-titanate layer and electrodes for deriving the signals are arranged on the side of the silicon plate facing away from the infrared filter.
  • an air equalization is located on the top of the silicon plate.
  • a silicon dioxide layer and a noble metal layer are located between the silicon plate and the lead zirconate titanate layer, the noble metal layer being in direct contact with the lead zirconate titanate layer. It is particularly preferred if the precious metal layer consists of platinum.
  • the top of the silicon plate and the part of the silicon dioxide layer not covered by the silicon plate is covered by an absorber layer.
  • a Fresnel lens zone optical plate onto the remaining webs of the silicon module plate via the openings etched out of the silicon module plate and to glue the resulting combination of silicon wafer, infrared filter plate and Fresnel lens zone optics in separate Sawing chips and processing them directly into a passive infrared motion detector.
  • a pyroelectric sensor according to the invention is shown in cross section.
  • the pyroelectric sensor essentially consists of a base 1 which carries a cap 3.
  • the cap 3 encloses the interior of the pyroelectric sensor; in its upper cover 5 it has an opening 5 which is closed by an IR filter 9.
  • the base 9 forms the lower end of the interior of the pyroelectric sensor.
  • a hybrid 13 on its upper side and an adapted system-integrated circuit (ASIC) 15 or a microprocessor thereon.
  • ASIC system-integrated circuit
  • the connection between the sensor and the hybrid 13 is established by a contact bracket 17.
  • the mechanical and electrical connection to the components takes place via the contact pins 19.
  • FIG. 2 shows a section of a cross section through a pyroelectric sensor according to the invention according to FIG. 1 on an enlarged scale.
  • a silicon dioxide layer 27, a platinum layer 29 and a layer of lead-zirconate-titanate (PZT layer) 31 are located on top of one another (in FIG. 2 from top to bottom) on a silicon wafer 11 which has a recess in the middle suitable for the passage of infrared radiation that represents the actual sensor.
  • the PZT layer 31 contains the two electrodes 33, which derive the electrical signals and feed them via the contact pins 19 (FIG. 1) to an evaluation circuit (not shown).
  • the silicon wafer 11 On the side facing away from the electrodes 33, the silicon wafer 11 is covered by an absorber layer 25; there is a plane-parallel plate 9, which represents the infrared filter. At the top of the silicon wafer 11, an air equalizer 23 is provided below the IR filter 9.
  • FIG. 1 The arrangement of the electrodes 33 on the PZT layer 31 can be seen in FIG.
  • the electrodes 33 are evaporated onto the PZT layer 31.
  • Figure 4 shows the arrangement of Figure 3 in cross section.
  • FIG. 5 shows a circuit for a pyroelectric sensor according to the invention.
  • the two sensor elements 35 are oppositely polarized, connected in series with one another (dual sensor).
  • a load resistor 37 is connected in parallel.
  • a field effect transistor 39 serves as the amplifier element.
  • FIG. 6 shows a preferred use of a pyroelectric sensor shown in cross section according to FIG.
  • FIG. 6 shows a passive infrared motion detector which was obtained by gluing Fresnel lens zone optics 7 onto the infrared filter plate 9.
  • This enables a particularly simple manufacture of a passive infrared motion detector, cf. Embodiment 2.
  • the advantage of this arrangement is that the individual components of the detector are firmly connected to each other, so that a special adjustment is not necessary.
  • a manufacturing method for a pyroelectric sensor according to the present invention is described in the following embodiment 1.
  • the production of a passive infrared motion detector using a pyroelectric sensor according to the invention is described in embodiment 2.
  • a silicon module plate of suitable size and thickness (400 ⁇ m) is cleaned with dilute hydrofluoric acid to remove the oxide layer.
  • a 1 to 2 ⁇ m thick silicon dioxide layer 27 is applied by chemical vapor deposition.
  • a thin platinum layer 29 is evaporated onto this silicon dioxide layer 27.
  • An organic PZT solution is spun onto the platinum layer 29 produced in this way, and the organic solvent is evaporated at about 400 ° C. by brief heat treatment. This treatment is repeated several times until an approximately 1 ⁇ m thick layer of amorphous lead zirconate titanate has formed.
  • This PZT layer 31 is brought to crystallization by heating to 600 to 800 ° C.
  • the electrodes 33 are evaporated onto this PZT layer 31.
  • approximately 300 ⁇ m wide slots are sawn into the silicon, which later serve as air compensation 23.
  • a photoresist is applied to the back of the silicon wafer at the locations that are not to be etched, and the silicon is anisotropically etched down to the silicon dioxide layer 27 at the locations that are not covered.
  • An absorber layer 25 is applied to the etched silicon 11. This covers the silicon dioxide layer 27 at the points at which the silicon has been completely etched away.
  • the infrared filter 9 is glued onto the absorber layer 25. Because the silicon has been partially etched away, cavities are created between the IR filter 9 and the silicon dioxide layer 27, which provide air compensation via the slots cut into the silicon layer 11.
  • the hybrid 13 with the electronic components ASIC 15 is glued onto the base 1, and a contact bracket 17 for the electrically conductive connection between the PZT layer 31 and the ASIC 15 is glued onto the hybrid 13.
  • the cap 3 with the glued-in chip (consisting of silicon module plate 11 and IR filter 9) is welded onto the base 1 and results in the finished pyroelectric sensor.
  • Example 1 a silicon module plate of suitable size and thickness is used, which is processed exactly as described in Example 1.
  • a Fresnel zone optical module plate 7 is glued onto the side of the infrared filter layer facing away from the absorber layer 25.
  • the entire package of silicon module plate 11, infrared filter plate 9 and Fresnel zone optical module plate 7 is then sawn into individual chips, which are then individually glued into cap 3, as described in exemplary embodiment 1.
  • the further processing is carried out analogously to the method described in exemplary embodiment 1 and results in a finished passive infrared motion detector.
EP93113077A 1992-08-14 1993-08-16 Capteur pyroélectrique pour détecteurs infrarouges et passifs de mouvement Withdrawn EP0588073A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH254692A CH684446A5 (de) 1992-08-14 1992-08-14 Passiver Infrarotbewegungsdetektor.
CH2546/92 1992-08-14

Publications (1)

Publication Number Publication Date
EP0588073A1 true EP0588073A1 (fr) 1994-03-23

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EP93113077A Withdrawn EP0588073A1 (fr) 1992-08-14 1993-08-16 Capteur pyroélectrique pour détecteurs infrarouges et passifs de mouvement

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EP (1) EP0588073A1 (fr)
CH (1) CH684446A5 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19607608C2 (de) * 1996-02-29 2003-04-03 Abb Patent Gmbh Bewegungsmelder mit mindestens einem Dualsensor zur Detektion von Wärmestrahlung

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988004038A1 (fr) * 1986-11-26 1988-06-02 Jacob Fraden Detecteur de mouvement
EP0347704A1 (fr) * 1988-06-23 1989-12-27 Heimann Optoelectronics GmbH Détecteur infrarouge

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1988004038A1 (fr) * 1986-11-26 1988-06-02 Jacob Fraden Detecteur de mouvement
EP0347704A1 (fr) * 1988-06-23 1989-12-27 Heimann Optoelectronics GmbH Détecteur infrarouge

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CH684446A5 (de) 1994-09-15

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