Illuminance sensor, proximity sensor, and display device including the sensor

Patent metadata

Field	Value
Publication number	US-9831373-B2
Application number	US-201314420841-A
Country	US
Kind code	B2
Filing date	Jul 9, 2013
Priority date	Sep 11, 2012
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

In order to provide a single-unit sensor which serves as both an illuminance sensor and a proximity sensor, the sensor ( 1 ) includes a light receiving element section (E 1 ), an infrared cut-off filter (IRcutF), and a switching section (SWS) for switching spectral characteristics of the light receiving element section (E 1 ). The infrared cut-off filter (IRcutF) has an opening, and an infrared light receiving P-N junction (PDir) is provided at a location deeper in a substrate than a visible light receiving P-N junction (PDvis).

First claim

The invention claimed is:

1. A sensor comprising:
a first light receiving element section which is provided in a substrate, the first light receiving element section having (i) a first visible light receiving P-N junction that has a visible spectral characteristic and (ii) a first infrared light receiving P-N junction that has an infrared spectral characteristic;
an infrared cut-off filter which is provided so as to cover the first light receiving element section, the infrared cut-off filter removing an infrared component from light; and
a first switching section for switching spectral characteristics of the first light receiving element section,
the infrared cut-off filter having an opening, and
the first infrared light receiving P-N junction being provided at a location deeper in the substrate than the visible light receiving P-N junction.

2. The sensor as set forth in claim 1 , wherein:
the opening is provided in the infrared cut-off filter so as to surround the first light receiving element section.

3. The sensor as set forth in claim 1 , wherein:
the first switching section switches a spectral characteristic of the first light receiving element section to the infrared spectral characteristic or a visible-to-infrared spectral characteristic.

4. The sensor as set forth in claim 3 , wherein:
the first switching section selects, as a current signal to be outputted from the first light receiving element section, (i) a combined electric current which is obtained by combining a received light current outputted from the first visible light receiving P-N junction and a received light current outputted from the first infrared light receiving P-N junction or (ii) the received light current outputted from the first infrared light receiving P-N junction.

5. The sensor as set forth in claim 4 , wherein:
an anode of the first infrared light receiving P-N junction is connected with a ground;
a cathode of the first visible light receiving P-N junction is connected with a cathode of the first infrared light receiving P-N junction;
a connection node between the cathode of the first visible light receiving P-N junction and the cathode of the first infrared light receiving P-N junction serves as an output node of the first light receiving element section;
the first switching section includes a first switch and a second switch;
one end of the first switch is connected with the output node;
another end of the first switch is connected with one end of the second switch;
another end of the second switch is connected with a ground; and
an anode of the first visible light receiving P-N junction is connected with a connection node between the another end of the first switch and the one end of the second switch.

6. The sensor as set forth in claim 1 , further comprising:
a second light receiving element section which has a second infrared light receiving P-N junction having an infrared spectral characteristic,
the second light receiving element section being provided in a part of the substrate which part corresponds to the opening.

7. The sensor as set forth in claim 6 , wherein:
the second light receiving element section further has a second visible light receiving P-N junction having a visible spectral characteristic; and
said sensor further comprises a second switching section for switching spectral characteristics of the second light receiving element section.

8. The sensor as set forth in claim 7 , wherein:
the second switching section switches a spectral characteristic of the second light receiving element section to the infrared spectral characteristic or a visible-to-infrared spectral characteristic.

9. The sensor as set forth in claim 8 , wherein:
the second switching section selects, as an output current from the second light receiving element section, (i) a combined electric current which is obtained by combining a received light current outputted from the second visible light receiving P-N junction and a received light current outputted from the second infrared light receiving P-N junction or (ii) the received light current outputted from the second infrared light receiving P-N junction.

10. The sensor as set forth in claim 9 , wherein:
an anode of the second infrared light receiving P-N junction is connected with a ground;
a cathode of the second visible light receiving P-N junction is connected with a cathode of the second infrared light receiving P-N junction;
a connection node between the cathode of the second visible light receiving P-N junction and the cathode of the second infrared light receiving P-N junction serves as an output node of the second light receiving element section;
the second switching section includes a first switch and a second switch;
one end of the first switch is connected with the output node;
another end of the first switch is connected with one end of the second switch;
another end of the second switch is connected with a ground; and
an anode of the second visible light receiving P-N junction is connected with a connection node between (i) the another end of the first switch and (ii) the one end of the second switch.

11. The sensor as set forth in claim 6 , further comprising:
a first specific color filter which causes light having a first specific color to pass through; and
a second specific color filter which causes light having a second specific color to pass through,
the first specific color filter being provided so as to cover the first light receiving element section, and
the second specific color filter being provided so as to cover the second light receiving element section.

12. The sensor as set forth in claim 11 , wherein the second specific color is blue.

13. The sensor as set forth in claim 11 , wherein the first specific color is red, green, or blue.

14. The sensor as set forth in claim 13 , wherein the first specific color is green.

15. The sensor as set forth in claim 1 , wherein a width of the opening is 5 um or greater.

16. The sensor as set forth in claim 1 , wherein the infrared cut-off filter is a metal multilayer film.

17. The sensor as set forth in claim 16 , wherein the metal multilayer film includes a layer of SiO 2 and a layer of Nb 2 O 5 .

18. A display device comprising:
a liquid crystal panel for displaying a screen;
a backlight for emitting light toward the liquid crystal panel;
a backlight control section for controlling a luminance of the backlight; and
a sensor recited in claim 1 ,
the backlight control section controlling the luminance of the backlight based on a signal outputted from the sensor.

19. A mobile telephone comprising a display device recited in claim 18 .

20. A digital camera comprising a display device recited in claim 18 .

Assignees

• Sharp Kk

Inventors

• Inoue Takahiro
• Kimura Tadamasa

Classifications

• G01J3/51

  using colour filters · CPC title

• G01J1/4228

  arrangements with two or more detectors, e.g. for sensitivity compensation · CPC title

• G01J1/44

  Electric circuits {(for command of an exposure part G03B7/02)} · CPC title

• H01L31/1013

  Electricity · mapped topic

• G01J1/4204 Primary

  with determination of ambient light (solar light G01J2001/4266) · CPC title