Infrared Proximity Sensor Package with Improved Crosstalk Isolation

{
  "publication_number": "US2011121181A1",
  "country": "US",
  "kind": "A1",
  "title": "Infrared Proximity Sensor Package with Improved Crosstalk Isolation",
  "abstract": "Disclosed are various embodiments of an infrared proximity sensor package comprising an infrared transmitter die, an infrared receiver die, a housing comprising sidewalls, a first recess, a second recess, a partitioning divider disposed between the first and second recesses, and an overlying shield comprising an infrared-absorbing material. The transmitter die is positioned in the first recess, and the receiver die is positioned within the second recess. The partitioning divider comprises liquid crystal polymer (LCP) such that the partitioning divider and the infrared-absorbing material of the shield cooperate together to substantially attenuate and absorb undesired infrared light that might otherwise become internally-reflected within the housing or incident upon the receiver as a false proximity or object detection signal.",
  "claims": [
    "1. An infrared proximity sensor package, comprising: an infrared transmitter; an infrared receiver; a shield disposed atop the package and having first and second apertures disposed therethrough and positioned over the infrared transmitter and the infrared receiver, respectively, such that infrared light emitted by the transmitter passes through the first aperture and infrared light reflected from an object to be detected passes through the second aperture for detection by the receiver, the shield comprising an infrared-absorbing material disposed on at least a top surface thereof; a housing comprising sidewalls, a first recess, a second recess and a partitioning divider disposed between the first and second recesses; wherein the transmitter is disposed in the first recess, the receiver is disposed in the second recess, and the partitioning divider comprises liquid crystal polymer (LCP) such that the partitioning divider and the infrared-absorbing material of the shield cooperate together to substantially attenuate and absorb undesired infrared light that may otherwise become internally-reflected within the housing or incident upon the receiver as a false signal. 2. The infrared proximity sensor package of claim 1, wherein the thickness T of the partitioning divider exceeds about 0.4 mm such that at least about 90% of the infrared light internally-reflected within the housing is not detected by the receiver and is attenuated or absorbed by the shield and the LCP. 3. The infrared proximity sensor package of claim 1, wherein the thickness T of the partitioning divider exceeds about 0.5 mm such that at least about 95% of the infrared light internally-reflected within the housing is not detected by the receiver and is attenuated or absorbed by the shield and the LCP. 4. The infrared proximity sensor package of claim 1, wherein the thickness T of the partitioning divider exceeds about 0.6 mm such that at least about 97% of the infrared light internally-reflected within the housing is not detected by the receiver and is attenuated or absorbed by the shield and the LCP. 5. The infrared proximity sensor package of claim 1, wherein top and side surfaces of the shield are black. 6. The infrared proximity sensor package of claim 1, wherein the shield comprises an infrared-absorbing polymer. 7. The infrared proximity sensor package of claim 6, wherein the infrared-absorbing polymer comprises LCP. 8. The infrared proximity sensor package of claim 1, wherein the shield is a black coating. 10. The infrared proximity sensor package of claim 1, further comprising a lead frame configured to fit beneath the housing, the transmitter being disposed on a first frame portion thereof, the receiver being disposed on a second frame portion thereof such that the transmitter is positioned within the first recess and the receiver is positioned within the second recess. 11. The infrared proximity sensor package of claim 1, wherein the sidewalls of the housing comprise LCP such that infrared light internally-reflected within the housing in the direction of the sidewalls is substantially attenuated or absorbed by the LCP contained therein. 12. The infrared proximity sensor package of claim 1, wherein the housing is molded from LCP. 13. The infrared proximity sensor package of claim 1, further comprising a processor operably coupled to the transmitter and the receiver, the processor comprising transmitter driving circuitry, receiver detection circuitry and signal conditioning circuitry. 14. The infrared proximity sensor package of claim 1, wherein the transmitter comprises an infrared LED transmitter. 15. The infrared proximity sensor package of claim 1, wherein the receiver comprises at least one of a PIN diode, a photo-diode and a phototransistor. 16. The infrared proximity sensor package of claim 1, wherein at least one of the transmitter and the receiver is configured for operation within a bandwidth ranging between about 800 nm and about 1100 nm, or between about 850 nm and about 900 nm. 17. The infrared proximity sensor package of claim 1, wherein the sensor package is incorporated into an electronic device selected from the group consisting of a portable electronic device, a hand-held portable electronic device, a stationary electronic device, a washing machine, a dryer, an exercise machine, an industrial control or switching device, a camera, a toy, a mobile telephone, a cellular telephone, a portable music player, a remote control, a television, an air conditioning unit, a heating unit, an audio playback device, an audio recording device, an MP3 player, a laptop computer, a personal data assistant (PDA), a radio, and a transceiver. 18. The infrared proximity sensor package of claim 1, wherein the sensor package is incorporated into a telephone and operably connected to at least one of an auto-volume adjustment circuit and an open-phone detection circuit. 19. The infrared proximity sensor package of claim 1, further comprising a lens disposed over at least one of the transmitter die and the receiver die. 20. The infrared proximity sensor package of claim 19, wherein the lens is configured to act as a low-cut filter that at least partially rejects wavelengths of light less than about 700 nm. 21. The infrared proximity sensor package of claim 14, wherein the lens is formed from a thermoset epoxy or a polymer. 22. The infrared proximity sensor package of claim 1, wherein at least one of a length and a width of the package is less than about 5 mm. 23. The infrared proximity sensor package of claim 1, wherein a height of the package is less than at least one of about 3 mm, about 2 mm, and about 1.2 mm. 24. A method of making an infrared proximity sensor package, comprising: providing an infrared transmitter; providing an infrared receiver; providing a shield disposed atop the package and having first and second apertures disposed therethrough and positioned over the infrared transmitter and the infrared receiver, respectively, such that infrared light emitted by the transmitter passes through the first aperture and infrared light reflected from an object to be detected passes through the second aperture for detection by the receiver, the shield comprising an infrared-absorbing material disposed on at least a top surface thereof; providing a housing comprising sidewalls, a first recess, a second recess and a partitioning divider disposed between the first and second recesses; positioning the transmitter within the first recess, and positioning the receiver within the second recess; wherein the partitioning divider comprises liquid crystal polymer (LCP) such that the partitioning divider and the infrared-absorbing material of the shield cooperate together to substantially attenuate and absorb undesired infrared light that may otherwise become internally-reflected within the housing or incident upon the receiver as a false signal."
  ],
  "description_excerpt": "Various embodiments relate to the field of infrared proximity sensor packages generally, devices which employ such packages, and methods of making and using same.\n\nMany optical proximity sensors known in the art are made using an infrared LED and an infrared light detector. Light from the LED is reflected from an object to be detected back to the detector, and the strength of the received signal is proportional to the distance of the object to be detected from the sensor. Such optical proximity sensors find applications in many portable devices such as mobile telephones, smart phones and PDAs, and can be used, by way of example, to activate or de-activate touch screens.\n\nExamples of optical proximity sensors include the AVAGO TECHNOLOGIES™ APDS-9120 and QPDS-9120 optical proximity sensor packages, which contain an integrated high efficiency infrared emitter and a detector or photodiode housed in a small form factor surface mount device (SMD) package. In the APDS-9120 optical proximity sensor package, as in many other proximity sensor packages manufactured by companies other than AVAGO TECHNOLOGIES™ such as SHARP™, ROHM™ and VISHAY™, an infrared transmitter die must be placed in very close proximity to an infrared receiver die (e.g., mere millimeters apart in the same package).\n\nOne significant issue in the design of optical proximity sensors is optical crosstalk, where stray light from the LED falls on the detector and can generate an undesired false signal mimicking a true proximity or object detection signal.",
  "cpc": [
    "G01S 17/04",
    "G01S 7/4813",
    "H03K 17/945",
    "H10W 90/756",
    "Y10T 29/49002"
  ],
  "ipc": [
    "G01J 5/00",
    "G01S 17/04",
    "G01S 7/481",
    "H03K 17/945"
  ],
  "assignees": [
    "Avago Technologies ECBU IP Singapore Pte Ltd"
  ],
  "inventors": [
    "James Costello",
    "Wee Sin Tan"
  ],
  "filing_date": "2009-11-23",
  "publication_date": "2011-05-26",
  "priority_date": "2009-11-23",
  "application_number": "US-62376709-A",
  "family_id": "43902233",
  "cited_by_count": 101,
  "citations": [
    "US5155777A",
    "US5367393A",
    "US5567953A",
    "US5675143A",
    "US5811797A",
    "US7289142B2",
    "US20060022212A1",
    "US7675132B2",
    "US6135816A",
    "US6064062A",
    "US20050088900A1",
    "US6364706B1",
    "US7172126B2",
    "US6771671B1",
    "US6674653B1",
    "US6677934B1",
    "US7026710B2",
    "US6760390B1",
    "US6635955B2",
    "US6855933B2",
    "US20040065894A1",
    "US6572410B1",
    "US6740862B2",
    "US6885300B1",
    "US7277012B2",
    "US20060049533A1",
    "US7109465B2",
    "US20070045524A1",
    "US20050110157A1",
    "US20070072321A1",
    "US7229295B2",
    "US7258264B2",
    "US20050199786A1",
    "US7510888B2",
    "US20080012033A1",
    "US7387907B2",
    "US20060011807A1",
    "US20060016994A1",
    "US20060045530A1",
    "US20080265266A1",
    "US7348536B2",
    "WO2006045531A1",
    "US20080197376A1",
    "US20080030878A1",
    "US20080179503A1",
    "US8026472B2",
    "US7387033B2",
    "US20070085157A1",
    "US20090129783A1",
    "US20070246646A1",
    "US20080011940A1",
    "US7514666B2",
    "US7485818B2",
    "US7582513B2",
    "US7437806B2",
    "US20080118241A1",
    "US8031174B2",
    "US20080165115A1",
    "US20080173790A1",
    "US20080173963A1",
    "US20080223934A1",
    "US20080296478A1",
    "US20080308917A1",
    "US20080308738A1",
    "US20090027652A1",
    "US20090057799A1",
    "US20090159900A1",
    "US7755029B2",
    "US7851246B2",
    "US20090168088A1",
    "US20090267173A1",
    "US7767485B2",
    "US20100030039A1",
    "US8207517B2",
    "US20100246771A1",
    "US20100282951A1",
    "US8420999B2",
    "US20110204233A1",
    "US20100327164A1",
    "US20110024627A1",
    "US20110057102A1",
    "US8097852B2",
    "US20110057129A1",
    "US8143608B2",
    "US8275922B2",
    "US20110297831A1",
    "US20120070145A1",
    "US8575537B2",
    "US20120160994A1"
  ]
}