Synchronization of image acquisition in multiple image sensors with a synchronization clock signal

{
  "publication_number": "US2014225998A1",
  "country": "US",
  "kind": "A1",
  "title": "Synchronization of image acquisition in multiple image sensors with a synchronization clock signal",
  "abstract": "A multiple image sensor image acquisition system includes a clock control unit to generate a synchronization clock signal. The synchronization clock signal has a prolonged constant cycle during which the synchronization clock signal is held at a constant level for a period of time corresponding to multiple clock cycles. A first image sensor is coupled with the clock control unit to receive the synchronization clock signal and has a first synchronization unit that is operable to synchronize operation for the first image sensor based on detection of an end of the prolonged constant cycle. A second image sensor is coupled with the clock control unit to receive the synchronization clock signal and has a second synchronization unit that is operable to synchronize operation for the second image sensor based on detection of the end of the prolonged constant cycle. The image sensors are synchronized operationally.",
  "claims": [
    "1. A multiple image sensor image acquisition system comprising: a clock control unit to generate a synchronization clock signal, the synchronization clock signal having a prolonged constant cycle during which the synchronization clock signal is held at a constant level for a period of time corresponding to multiple clock cycles; a first image sensor coupled with the clock control unit to receive the synchronization clock signal, the first image sensor having a first synchronization unit that is operable to synchronize image acquisition for the first image sensor based on detection of an end of the prolonged constant cycle; and a second image sensor coupled with the clock control unit to receive the synchronization clock signal, the second image sensor having a second synchronization unit that is operable to synchronize image acquisition for the second image sensor based on detection of the end of the prolonged constant cycle. 2. The system of claim 1, wherein the prolonged constant cycle comprises a prolonged high cycle during which the synchronization clock signal is held high for the period of time. 3. The system of claim 2, wherein the first synchronization unit is operable to synchronize image acquisition for the first image sensor based on detection of a falling edge of the prolonged high cycle. 4. The system of claim 1, wherein the prolonged constant cycle comprises a prolonged low cycle during which the synchronization clock signal is held low for the period of time. 5. The system of claim 4, wherein the first synchronization unit is operable to synchronize image acquisition for the first image sensor based on detection of a rising edge of the prolonged low cycle. 6. The system of claim 1, wherein the first image sensor has a clock electrical contact structure to receive the synchronization clock signal, wherein the clock electrical contact structure is used to receive clock signals used by the first image sensor during the image acquisition. 7. The system of claim 1, further comprising a light control unit to turn a light on during the prolonged constant cycle and to turn the light off at the end of the prolonged constant cycle. 8. The system of claim 1, wherein the prolonged constant cycle corresponds in time to a vertical blanking period of the first image sensor. 9. The system of claim 8, wherein the prolonged constant cycle is used to prolong the vertical blanking period of the first image sensor. 10. The system of claim 1, wherein the first image sensor does not have a phase lock loop (PLL) to synchronize image acquisition for the first image sensor. 11. The system of claim 1, wherein the first image sensor does not have a dedicated synchronization electrical contact structure to receive a dedicated synchronization signal. 12. The system of claim 1, wherein the first and second image sensors are disposed within a distal end of an endoscope. 13. A method of synchronizing image sensors comprising: generating a synchronization clock signal, the synchronization clock signal having a prolonged constant cycle during which the synchronization clock signal is held at a constant level for a period of time corresponding to multiple clock cycles; synchronizing image acquisition for a first image sensor based on detection of an end of the prolonged constant cycle; and synchronizing image acquisition for a second image sensor based on detection of the end of the prolonged constant cycle. 14. The method of claim 13, wherein generating comprises generating the synchronization clock signal having a prolonged high cycle during which the synchronization clock signal is held high for the period of time, and wherein synchronizing the image acquisition for the first image sensor is based on detection of a falling edge of the prolonged high cycle. 15. The method of claim 13, wherein generating comprises generating the synchronization clock signal having a prolonged low cycle during which the synchronization clock signal is held low for the period of time, and wherein synchronizing the image acquisition for the first image sensor is based on detection of a rising edge of the prolonged low cycle. 16. The method of claim 13, further comprising: receiving the synchronization clock signal on a clock electrical contact structure of the first image sensor; and receiving clock signals on the clock electrical contact structure of the first image sensor during the image acquisition. 17. The method of claim 13, further comprising: turning a light on during the prolonged constant cycle; and turning the light off at the end of the prolonged constant cycle. 18. The method of claim 13, wherein generating comprises generating the synchronization clock signal having the prolonged constant cycle which corresponds in time to a vertical blanking period of the first image sensor. 19. The method of claim 13, wherein synchronizing the image acquisition for the first image sensor is performed without using a phase lock loop (PLL)."
  ],
  "cpc": [
    "H04N 23/74",
    "H04N 23/555",
    "H04N 25/531",
    "H04N 5/3765",
    "H10F 39/80"
  ],
  "assignees": [
    "OMNIVISION TECH INC"
  ],
  "filing_date": "2014-04-15",
  "publication_date": "2014-08-14",
  "priority_date": "2011-11-14",
  "application_number": "US-201414253699-A",
  "family_id": "51297198",
  "citations": [
    "US2006284053A1",
    "US2007139521A1",
    "US2009216080A1"
  ]
}