Electronic devices having ambient light sensors with electrostatic shields
An electronic device may be provided with a display. An opaque layer may be formed on an inner surface of a display cover layer in an inactive area of the display. An optical component window may be formed from the opening and may be aligned with an ambient light sensor such as a color ambient light sensor. The color ambient light sensor may have photodetectors on a light detector integrated circuit. Electrostatic shielding may be incorporated into the color ambient light sensor to prevent perturbations in the output of the color ambient light sensor due to the presence of electrostatic charge in the vicinity of the optical component window. The shielding may include a grounded shield layer on a surface of an ambient light sensor support structure that faces the display cover layer and may include a transparent shield layer overlapping the photodetectors.
1. An electronic device, comprising:
a transparent member having an optical component window;
a support structure having a surface facing the transparent member;
a light detector integrated circuit coupled to the support structure;
an electrostatic shield layer on the surface that is configured to shield the light detector; and
optical components in the support structure between the light detector and the transparent member.
2. The electronic device defined in claim 1 further comprising a signal path that is configured to short the electrostatic shield layer to a fixed potential.
3. The electronic device defined in claim 2 wherein the optical components comprise a light diffuser.
4. The electronic device defined in claim 3 wherein the optical components comprise a visible-light-transmitting-and-infrared-light-blocking filter.
5. The electronic device defined in claim 4 wherein the optical components comprise a light guide interposed between the light diffuser and the visible-light-transmitting and-infrared-light-blocking filter.
6. The electronic device defined in claim 2 wherein the support structure comprises a plastic support having an interior in which the optical components are mounted and having an exterior surface on which the signal path is formed.
7. The electronic device defined in claim 2 wherein the light detector integrated circuit comprises a plurality of photodetectors overlapped by respective color filters of different colors.
8. The electronic device defined in claim 7 further comprising:
a display having a brightness; and
control circuitry configured to adjust the brightness based on information from the light detector integrated circuit.
9. The electronic device defined in claim 8 wherein the photodetectors include photodetectors corresponding to a clear channel and to a channel of a given color and wherein the control circuitry is configured to adjust the brightness at least partly in response to a ratio of an output from the clear channel to an output from the channel of the given color.
10. The electronic device defined in claim 1 wherein the light detector integrated circuit includes photodetectors and wherein the light detector integrated circuit further comprises an additional electrostatic shield layer covering the photodetectors.
11. The electronic device defined in claim 10 wherein the additional electrostatic shield layer comprises a layer of transparent conductive material.
12. The electronic device defined in claim 11 further comprising a signal path configured to short the layer of transparent conductive material to a fixed potential.
13. An electronic device, comprising:
an array of pixels configured to display images;
a display cover layer that overlaps the pixels;
an optical component window in a portion of the display cover layer through which ambient light passes; and
a color ambient light sensor aligned with the optical component window, wherein the color ambient light sensor includes:
an opaque support structure;
a light detector integrated circuit that is at least partially surrounded by the opaque support structure, wherein the light detector integrated circuit has a plurality of photodetectors each overlapped by a color filter that is configured to pass a different respective band of visible light wavelengths; and
an electrostatic shield configured to shield the light detector integrated circuit from signal perturbations.
14. The electronic device defined in claim 13 wherein the opaque support structure has a surface facing the display cover layer and wherein the electrostatic shield comprises a metal layer on the surface that is shorted to a fixed potential.
15. The electronic device defined in claim 14 further comprising a layer of adhesive interposed between the surface and the display cover layer.
16. The electronic device defined in claim 13 wherein the electrostatic shield comprises a transparent conductive layer on the light detector integrated circuit that overlaps the photodiodes and is shorted to a fixed potential.
17. The electronic device defined in claim 16 wherein the opaque support structure has a surface facing the display cover layer and wherein the electronic device further comprises a metal layer on the surface that is shorted to the fixed potential.
18. The electronic device defined in claim 13 further comprising:
a flexible printed circuit with metal traces;
a signal path on the support structure that shorts the electrostatic shield to a trace at a fixed potential in the metal traces.
19. An electronic device, comprising:
a display having a display cover layer;
an ambient light sensor window in the display cover layer; and
an ambient light sensor configured to receive ambient light through the ambient light sensor window, wherein the ambient light sensor comprises:
a light detector; and
a ring of metal at a fixed potential that surrounds the ambient light sensor window and that faces an inner surface of the display cover layer, wherein the ring of metal is configured to serve as an electrostatic shield for the light detector.
20. The electronic device defined in claim 19 wherein the light detector comprises:
a plurality of photodetectors; and
a layer of transparent conductive material at the fixed potential that overlaps the photodetectors.