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OPT3002: A solution that uses light to determine whether a hand is being held over something

Conor
Guru 12065 points
Part Number: OPT3002

Tool/software:

Hi,

I have a question about light sensors. I'm looking for an IC for use with faucets that can determine whether a person is holding their hand over it using light.

TI has the OPT series in their lineup, but would it be suitable for this purpose?

If you have any recommended products, please let me know.

Thanks,

Conor

  • 0
    TI__Genius 10080 points

    Hi Conor,

    Thank you for posting to the Sensing forum.

    It is possible to use an ambient light sensor to detect a change in illumination as someone places their hand over a faucet. The OPT3002 has a wide spectral bandwidth, ranging from 300nm to 1000nm. This would be good for a system that requires detection of a variety of wavelengths.

    The OPT3002 can be used to continuously measure ambient light in the surrounding area, and as someone places their hand over the faucet the light reaching the sensor will drastically decrease. The OPT3002 has an Interrupt pin that can be used to alert the MCU that a low light threshold has been crossed, indicating that a hand is blocking the sensor. This use case is assuming that the surrounding area is not dark.

    Best regards,

    Nicole

  • 0 in reply to Nicole Khoury
    Guru 12065 points

    Hi Nicole,

    Thank you for your comment!
    If considering a TI light sensor for the above application, is the OPT3002 the optimal solution? If there is a different part number, please let me know.
    Also, if you have any sensing design information (application notes), please share it.

    Thanks,

    Conor

  • +1 in reply to Conor
    TI__Genius 10080 points

    Hi Conor,

    Further suggestions would depend on the system requirements (sensor speed, sensitivity, etc.). For example, the OPT4x family of device has programmable conversion times from 600µs to 800ms in 12 steps. The OPT3x family has 2 programmable conversion times: 100ms and 800ms. In addition to the faster conversion times, the OPT4x devices have a higher lux resolution.

    For more resources regarding choosing and designing a light sensor, please refer to the application report below:

    Best regards,
    Nicole

  • 0 in reply to Nicole Khoury
    Guru 12065 points

    Hi Nicole,

    Thank you for the good information.

    Has the OPTx series been used as a tap sensor in the market?

    Thanks,

    Conor

  • 0 in reply to Conor
    TI__Genius 10080 points

    Hi Conor,

    We have seen interest from customers for similar applications.

    Best regards,
    Nicole

  • 0 in reply to Nicole Khoury
    Guru 12065 points

    Hi Nicole,

    Thank you for the information. As I am considering using a light IC, I would like to know the advantages and disadvantages of using it in comparison with the infrared triangulation method that uses a line sensor.

    Thanks,

    Conor

  • 0 in reply to Conor
    TI__Genius 10080 points

    Hi Conor,

    There may be challenges using a light sensor when the ambient environment is dark. Detecting the hand would require measuring a change in light levels, which may become more difficult if there is little or no ambient illumination.

    Best regards,

    Nicole

  • 0 in reply to Nicole Khoury
    Guru 12065 points

    Hi Nicole,

    You mention the disadvantages of light sensors. These are unlikely to be an issue since sensing is done primarily in bright environments. I would also be grateful if you could comment on the advantages compared to line sensors.

    Thanks,

    Conor

  • 0 in reply to Conor
    TI__Genius 10080 points

    Hi Conor,

    The IR triangulation method works well but will be more complex to implement. For your system needs, using an ambient light sensor may be a more straightforward solution.

    I am not overly familiar with IR triangulation using line sensors, but this is what I have gathered from researching online.

    Best regards,
    Nicole