Systems and methods for optical sensing using point-based illumination

1. An optical sensing system, comprising:

a display substrate;

a plurality of display elements;

a sensor light source for illuminating a sensing region, wherein the sensor light source is separate from the plurality of display elements, and wherein the sensor light source is disposed under the display substrate; and

a detector for detecting light from the sensing region;

wherein the plurality of display elements comprises a color filter, a liquid crystal material disposed between the display substrate and the color filter, and a backlight disposed under the display substrate, and

wherein the sensor light source comprises a micro LED arranged in a cluster of multiple micro LEDs.

2. The optical sensing system of claim 1 , wherein the sensor light source is disposed in an opaque region of an active area of the display substrate.

3. The optical sensing system of claim 1 , further comprising a dummy pattern disposed over the backlight, the dummy pattern comprising a plurality of light blocking features disposed between the backlight and the display substrate.

4. The optical sensing system of claim 1 , wherein a width of the sensor light source or a width of the cluster is configured to emit light around a shadowing feature disposed in an illumination path between the sensor light source and the sensing region.

5. The optical sensing system of claim 1 , wherein the plurality of display elements comprises display pixel circuitry disposed over the display substrate, wherein the optical sensing system further comprises:

a transparent cover sheet disposed over the display pixel circuitry, wherein a top surface of the transparent cover sheet provides a sensing surface for an object;

wherein the sensor light source is disposed under the display substrate; and

wherein the detector includes a plurality of photosensors disposed under the display substrate.

6. The optical sensing system of claim 5 , further comprising:

a low index layer disposed below the display substrate and disposed over the plurality of photosensors, wherein the low index layer is not disposed over the sensor light source, and wherein the low index layer has an index of refraction lower than the display substrate.

7. The optical sensing system of claim 6 , further comprising:

a light absorbing layer disposed in an area between the plurality of photosensors.

8. An optical sensing system, comprising:

a display substrate;

a plurality of display elements;

a sensor light source for illuminating a sensing region, wherein the sensor light source is separate from the plurality of display elements, and wherein the sensor light source is disposed under the display substrate;

a detector for detecting light from the sensing region;

wherein the plurality of display elements comprises a color filter, a liquid crystal material disposed between the display substrate and the color filter, and a backlight disposed under the display substrate, wherein the color filter comprises a color filter layer having an opaque portion and a plurality of different subpixel color filters, wherein the color filter layer is disposed over the liquid crystal material;

a display pixel circuitry for applying current to the liquid crystal material, wherein the display pixel circuitry is disposed over the display substrate; and

a transparent cover sheet disposed over the color filter, wherein a top surface of the transparent cover sheet comprises a fingerprint sensing surface disposed within an areal extent of an active area of the display substrate;

wherein the sensor light source comprises a micro light emitting diode (LED) for illuminating a finger contacting the fingerprint sensing surface with emitted light, wherein the micro LED is disposed within the areal extent of the active area; and

wherein the detector comprises a detector array having a plurality of photosensors for detecting returned light from the fingerprint sensing surface, wherein the returned light corresponds to interaction of the emitted light with the finger, wherein the plurality of photosensors are disposed within the areal extent of the active area.

9. The optical sensing system of claim 8 , wherein the micro LED is disposed between the backlight and the display substrate or is disposed between the display substrate and the color filter layer.

10. The optical sensing system of claim 8 , wherein the opaque portion of the color filter layer comprises a black matrix.

11. The optical sensing system of claim 8 , wherein the plurality of photosensors are disposed over the display substrate.

12. An optical sensing system, comprising:

a display substrate;

a plurality of display elements;

a sensor light source for illuminating a sensing region, wherein the sensor light source is separate from the plurality of display elements, and wherein the sensor light source is disposed under the display substrate; and

a detector for detecting light from the sensing region;

wherein the detector includes a detector array disposed over the display substrate, wherein the detector array comprises a plurality of photosensors arranged a plurality of rows and a plurality of columns; wherein the sensor light source is disposed in a first position aligned with one of the rows and one of the columns, wherein the first position is free of any photosensor.

13. The optical sensing system of claim 12 , further comprising:

processing circuitry coupled to the detector array, wherein the processing circuitry is configured to receive a plurality of pixel values from the plurality of photosensors, and wherein the processing circuitry is configured to determine a value of a pixel corresponding to the first position based on one or more pixel values of the plurality of pixel values.

14. The optical sensing system of claim 13 , wherein the processing circuitry is configured to determine the value of the pixel by interpolating a plurality of surrounding pixel values that surround the first position.

15. An optical sensing system, comprising:

a display substrate;

a plurality of display elements;

a sensor light source for illuminating a sensing region, wherein the sensor light source is separate from the plurality of display elements, and wherein the sensor light source is disposed under the display substrate;

a detector for detecting light from the sensing region; and

a display pixel circuitry disposed over the display substrate;

wherein the plurality of display elements comprises a plurality of organic light emitting diode (OLED) sub-pixels for displaying visible images;

wherein the sensor light source includes a sensor OLED separate from the plurality of OLED sub-pixels, wherein the sensor OLED is disposed over the display substrate.

16. The optical sensing system of claim 15 , wherein the sensor OLED is configured to be driven with a higher current than the plurality of OLED sub-pixels.

17. The optical sensing system of claim 15 , wherein the sensor OLED is configured to emit higher intensity light than the plurality of OLED sub-pixels.

18. The optical sensing system of claim 15 , further comprising one or more other sensor OLEDs in addition to the sensor OLED, wherein the sensor OLED and the one or more other sensor OLEDs are arranged in a cluster.