Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
  • H01L31/02—Details
  • H01L31/0203—Containers; Encapsulations, e.g. encapsulation of photodiodes
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K1/00—Printed circuits
  • H05K1/18—Printed circuits structurally associated with non-printed electric components

Definitions

• This invention relates to infrared detectors and in particular to infrared receivers having improved spatial coverage.
• Infrared receivers typically include an infrared photodiode detector.
• Such infrared detectors are maximally sensitive when the direction of propagation of the infrared beam is along an axis of the infrared detector. When this is not the case and the direction of propagation of the infrared beam is at an oblique angle to the axis of the infrared detector, the sensitivity falls off: sometimes acutely.
• Figures 1 and 2 are graphs showing the respective relative sensitivities of two infrared photodiode detectors provided by die Telefunken Company under the Catalogue Numbers BPV22NF and BPVIONF.
• the straight lines represent the angular direction of the infrared beam relative to the "normal", i.e. perpendicular to the plane of the detector element, e.g. silicon.
• the curved lines represent loci of equal sensitivity. From Figure 1, it is seen that for the BPV22NF which is considered a wide angle photodiode, when the propagation axis is at 10° to the normal, the drop in relative sensitivity is negligible.
• the relative sensitivity When the propagation axis increases to 40° to the normal, the relative sensitivity is equal to 0.8. With a propagation axis of 60°, the relative sensitivity falls to 0.5. When the propagation axis increases to 80° to the normal, the relative sensitivity falls to approximately 0.15. On the other hand, as seen in Figure 2, the BPVIO F is much more uni-directional. When the propagation axis is at 10° to the normal, the relative sensitivity already falls to 0.9. WTien the propagation axis is as little as 20° to the normal, the relative sensitivity falls to 0.5; and when the propagation axis is at 50° to the normal, the relative sensitivity falls drastically to 0.1.
• infrared diodes having improved spatial coverage characteristics. It is also known to employ optical techniques such as lenses for increasing the field of detection of the detector. It is also known to employ multiple infrared detectors so as effectively to increase the sensitivity of the receiver.
• the effective sensitivity of an infrared detector is a function of the area of silicon or other sensitive material in the infrared diode. Thus, by increasing the area of sihcon, the effective sensitivity of the detector can also be increased. By employing multiple detectors, therefore, it is possible to increase the effective area of sihcon and thus the effective sensitivity of the detector.
• an infrared receiver having improved spatial coverage, comprising: at least two mutually angularly spaced apart infrared photodiodes each having a respective axis of maximum sensitivity inclined at an acute angle to a common axis.
• At least two infrared detectors are employed each inclined at an acute angle to a common axis of the receiver. Consequently, a beam directed towards the receiver along the common axis thereof, will strike each of the infrared diodes at an oblique angle to its respective direction of maximum sensitivity. As a result, the signal intensity produced by each diode will be decreased relative to the maximum sensitivity of the diode.
• a beam directed at an obhque angle to the common axis of the receiver will be more likely to strike one of the infrared detectors along its axis of maximum sensitivity: thereby producing a relatively higher output notwithstanding the fact that such an oblique beam has actually travelled through a larger propagation distance.
• Such receiver may be mounted on a ceiling for relaying infrared signals from one floor-mounted device to another.
• ceiling-mounted receivers are particularly useful in infrared networks and the like since they are unobtrusive and well clear of furniture and other obstacles which might intercept the infrared beam and prevent its detection by the receiver.
• Figs. 1 and 2 are spatial sensitivity characteristics of typical known infrared detectors
• FIG. 3 shows schematically a pair of infrared detectors connected in accordance with one embodiment of the invention
• Fig. 4 shows schematically a pair of infrared detectors connected in accordance with a second embodiment of the invention.
• Fig. 5 shows pictorially an application of the invention to a ceiling mounted detector.
• FIG. 3 shows schematically a detail of an infrared receiver comprising a pair of discrete infrared photodiodes 10 and 11 each having respective axes of maximum sensitivity 12 and 13.
• the two photodiodes 10 and 11 are mounted on a common printed circuit board (PCB) 14 so that their respective axes of maximum sensitivity 12 and 13 are inclined at an acute angle ⁇ to a "common" axis 15 of the receiver.
• PCB printed circuit board
• a symmetrical arrangement is employed such that each of the photodiodes 10 and 11 is orientated at the same angle ⁇ to the common axis 15 of the receiver, this is not a requirement.
• improved spatial coverage will equally well be achieved even if each of the component diodes is orientated at a different angle to the common axis of the receiver.
• the photodiodes 10 and 11 are discrete components that are connected in parallel by means of conductive leads which are soldered to the PCB 14. Two external connections (not shown) allow the PCB 14 to be connected to the infrared receiver of which the photodiodes 10 and 11 are the active components.
• Fig. 4 shows schematically an alternative embodiment of a detector depicted generally as 20 and having a pair of infrared sensitive planes 21 and 22, such as sihcon, which are encapsulated in a common encapsulation for physical miniaturization and cost reduction.
• each sihcon plane may have two conductive leads which allow for the two infrared sensitive planes 21 and 22 to be connected in parallel.
• the photodiodes can be mounted on corresponding faces of a polyhedral structure such as, for example, a pyramid so as to provide effectively 360° coverage.
• a polyhedral structure such as, for example, a pyramid
• commonly connected leads from the component infrared sensitive planes are preferably connected internally so as to reduce the number of conductors projecting from the device.
• FIG. 5 there is shown an application of the invention to a detector 25 ceiling-mounted centrally in a room 26 for receiving a control signal from a hand-held transmitter (not shown) held at waist height by a person standing in a corner of the room. If the height of the room is 2.6 m, then the approximate height of the transmitter is 1.6 m allowing for the fact that the person's waist is approximately at a height of 1 m.
• the relevant data are as shown in the following table:
• the effective angle ⁇ of propagation between the infrared beam and the detector 25 is 77.2° to the vertical. At this angle, a single BPVIONF detector mounted normally so as to point directly downwards would have negligible relative sensitivity; whilst even for the wide angle
• the relative off-axis propagation of the infrared beam to at least one of the component infrared detectors may be minimized so that the response from that detector is substantially unimpaired.
• the beam would then strike each of the component photodiode detectors off axis, thereby reducing their response. It is thus seen that the invention sacrifices the sensitivity for a direct strike for the sake of the sensitivity for an indirect strike.
• the invention has general application for hand-held transceivers, such as badges, having receive capability.
• hand-held transceivers such as badges
• the invention may be provided an array according to the invention in order to improve the spatial coverage thereof.

Applications Claiming Priority (3)

Publications (1)

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ID=11071035

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• 1997
  • 1997-12-30 IL IL12280697A patent/IL122806A0/xx unknown
• 1998
  • 1998-11-05 AU AU97596/98A patent/AU9759698A/en not_active Abandoned
  • 1998-11-05 EP EP98951660A patent/EP1057221A1/de not_active Withdrawn
  • 1998-11-05 WO PCT/IL1998/000537 patent/WO1999035697A1/en not_active Application Discontinuation

Non-Patent Citations (1)

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