Image sensors for capturing both visible light images and infrared light images, and associated systems and methods

• US 10,051,211 B2
• Filed: 12/05/2013
• Issued: 08/14/2018
• Est. Priority Date: 12/05/2013
• Status: Active Grant

• Current Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Original Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Inventors: Chen, Gang, Mao, Duli, Tai, Dyson Hsinchih
• Primary Examiner(s): Czekaj, Dave
• Assistant Examiner(s): Sullivan, Tyler W
• Application Number:
  US14/097,843
• Publication Number:
  US 20150163418A1
• Time in Patent Office: 1,713 Days
• CPC Class Codes: H04N 23/11 for generating image signals from visible and infrared light wavelengths
• CPC Class Codes: H04N 23/667 Camera operation mode switching, e.g. between still and video, sport and normal or high- and low-resolution modes
• CPC Class Codes: H04N 25/131 including elements passing infrared wavelengths
• CPC Class Codes: H04N 25/135 based on four or more different wavelength filter elements

Abstract

An image sensor for capturing both visible light images and infrared light images includes a semiconductor substrate having length, width, and height, a plurality of visible light photodetectors disposed in the semiconductor substrate, and a plurality of combination light photodetectors disposed in the semiconductor substrate. Each of the plurality of visible light photodetectors has a respective depth in the height direction, and each of the plurality of combination light photodetectors has a respective depth in the height direction that is greater than the respective depth of each of the plurality of visible light photodetectors.

Claims

1. A system for imaging a scene, comprising:

an image sensor for capturing both visible light images and infrared light images, including;

a plurality of visible color filters,

a plurality of visible light photodetectors disposed in a single semiconductor substrate having a light-receiving top surface and a bottom surface there opposite, each of the plurality of visible light photodetectors (i) having a respective depth in a depth direction perpendicular to the light-receiving top surface, and (ii) being between a respective one of the plurality of visible color filters and the bottom surface, and

a plurality of white-IR filters each passing substantially only white light and infrared light,

a plurality of combination light photodetectors disposed in the single semiconductor substrate, each of the plurality of combination light photodetectors (a) having a respective depth in the depth direction that is greater than the respective depth of each of the plurality of visible light photodetectors, (b) being between a respective one of the plurality of white-IR color filters and the bottom surface,

(c) including a first portion and a second portion both located entirely between the light-receiving top surface and the bottom surface, the first portion disposed between the light-receiving top surface and the second portion, such that the first portion absorbs primarily white light and the second portion absorbs primarily infrared light, and

(d) being configured to generate a signal in response to the white light and infrared light incident on the combination light photodetector; and

a processor communicatively coupled to the image sensor and configured to execute machine-readable instructions to;

generate sensor data from respective signals generated by each of the plurality of visible light photodetectors and from respective signals generated by each of the plurality of combination light photodetectors, and

filter the sensor data to generate output data, such that;

the output data represents the signals generated by each of the plurality of visible light photodetectors, in a visible light operating mode of the system, and

the output data represents the signals generated by each of the plurality of combination light photodetectors, in an infrared light operating mode of the system.

2. The system of claim 1, the processor further configured to execute machine-readable instructions to:

generate a white light magnitude signal from the sensor data, the white light magnitude signal representing a sum of red light, green light and blue light incident on the image sensor;

generate a combination light magnitude signal from the sensor data, the combination light magnitude signal representing a sum of white and infrared light incident on the image sensor;

generate a difference signal by subtracting the white light magnitude signal from the combination light magnitude signal;

compare the difference signal to first and second threshold values;

switch from the visible light operating mode to the infrared light operating mode in response to the difference signal rising above the first threshold value; and

switch from the infrared light operating mode to the visible light operating mode in response to the difference signal falling below the second threshold value.

3. The system of claim 1, the processor further configured to execute machine-readable instructions to:

generate a white light magnitude signal from the sensor data, the white light magnitude signal representing green light incident on the image sensor;

generate a combination light magnitude signal from the sensor data, the combination light magnitude signal representing a sum of green and infrared light incident on the image sensor;

generate a difference signal by subtracting the white light magnitude signal from the combination light magnitude signal;

compare the difference signal to first and second threshold values,

switch from the visible light operating mode to the infrared light operating mode in response to the difference signal rising above the first threshold value, and

switch from the infrared light operating mode to the visible light operating mode in response to the difference signal falling below the second threshold value.

4. The system of claim 1, the processor further configured to execute machine-readable instructions to:

generate a visible light magnitude signal from the sensor data, the visible light magnitude signal representing a sum of red light, green light and blue light incident on the image sensor; and

compare the visible light magnitude signal to first and second threshold values,

switch from the visible light operating mode to the infrared light operating mode in response to the visible light magnitude signal falling below the first threshold value, and

switch from the infrared light operating mode to the visible light operating mode in response to the visible light magnitude signal rising above the second threshold value.

5. The system of claim 1, further comprising:

an infrared light source adapted to illuminate the scene with infrared light;

the processor being further configured to execute machine-readable instructions to;

activate the infrared light source in response to the system switching from the visible light operating mode to the infrared light operating mode, and

deactivate the infrared light source in response to the system switching from the infrared light operating mode to the visible light operating mode.

6. The system of claim 1, wherein, in each of the plurality of combination light photodetectors:

the first portion has a first cross-sectional area in a first plane perpendicular to the depth direction;

the second portion has a second cross-sectional area in a second plane parallel to the first plane; and

the second cross-sectional area is greater than the first cross-sectional area.

7. The system of claim 6, wherein the second portion of at least one of the plurality of combination light photodetectors extends under one or more the plurality of visible light photodetectors in the depth direction.