Image Sensors For Capturing Both Visible Light Images And Infrared Light Images, And Associated Systems And Methods

• US 20150163418A1
• Filed: 12/05/2013
• Published: 06/11/2015
• 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
• Granted Patent: US 10,051,211 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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. An image sensor for capturing both visible light images and infrared light images, comprising:

a semiconductor substrate having length, width, and height;

a plurality of visible light photodetectors disposed in the semiconductor substrate, each of the plurality of visible light photodetectors having a respective depth in the height direction; and

a plurality of combination light photodetectors disposed in the semiconductor substrate, each of the plurality of combination light photodetectors having a respective depth in the height direction that is greater than the respective depth of each of the plurality of visible light photodetectors.

2. The image sensor of claim 1, each of the plurality of combination light photodetectors comprising a first portion and a second portion stacked in the height direction, wherein:

the first portion has a lengthwise by widthwise first cross-sectional area;

the second portion has a lengthwise by widthwise second cross-sectional area; and

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

3. The image sensor of claim 2, 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 height direction.

4. The image sensor of claim 3, wherein in each of the plurality of combination light photodetectors, the first portion has an n-type doping of a first concentration, the second portion has an n-type doping of a second concentration, and the first concentration is greater than the second concentration.

5. The image sensor of claim 3, further comprising:

a plurality of red color filters adapted to pass substantially only red light, each of the plurality of red color filters in optical alignment with a respective one of the plurality of visible light photodetectors;

a plurality of green color filters adapted to pass substantially only green light, each of the plurality of green color filters in optical alignment with a respective one of the plurality of visible light photodetectors;

a plurality of blue color filters adapted to pass substantially only blue light, each of the plurality of blue color filters in optical alignment with a respective one of the plurality of visible light photodetectors; and

a plurality of white-IR color filters adapted to pass substantially only white light and infrared light, each of the plurality of white-IR color filters in optical alignment with a respective one of the plurality of combination light photodetectors;

the plurality of red, green, blue, and white-IR color filters collectively forming a red-green-blue-white color filter pattern.

6. The image sensor of claim 3, further comprising:

a plurality of red color filters adapted to pass substantially only red light, each of the plurality of red color filters in optical alignment with a respective one of the plurality of visible light photodetectors;

a plurality of green color filters adapted to pass substantially only green light, each of the plurality of green color filters in optical alignment with a respective one of the plurality of visible light photodetectors;

a plurality of blue color filters adapted to pass substantially only blue light, each of the plurality of blue color filters in optical alignment with a respective one of the plurality of visible light photodetectors; and

a plurality of green-IR color filters adapted to pass substantially only green light and infrared light, each of the plurality of green-IR color filters in optical alignment with a respective one of the plurality of combination light photodetectors;

the plurality of red, green, blue, and green-IR color filters collectively forming a Bayer color filter pattern.

7. A system for imaging a scene, comprising:

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

a semiconductor substrate having length, width, and height,

a plurality of visible light photodetectors disposed in the semiconductor substrate, each of the plurality of visible light photodetectors having a respective depth in the height direction, and

a plurality of combination light photodetectors disposed in the semiconductor substrate, each of the plurality of combination light photodetectors having a respective depth in the height direction that is greater than the respective depth of each of the plurality of visible light photodetectors;

a sensor data generator for generating 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

a channel controller adapted to 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.

8. The system of claim 7, the channel controller including:

a visible light magnitude module adapted 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;

a combination light magnitude module adapted to 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;

a subtraction module adapted to generate a difference signal by subtracting the visible light magnitude signal from the combination light magnitude signal; and

a comparison module adapted to;

compare the difference signal to first and second threshold values,

cause the system to 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

cause the system to 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.

9. The system of claim 7, the channel controller including:

a visible light magnitude module adapted to generate a visible light magnitude signal from the sensor data, the visible light magnitude signal representing green light incident on the image sensor;

a combination light magnitude module adapted to 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;

a subtraction module adapted to generate a difference signal by subtracting the visible light magnitude signal from the combination light magnitude signal; and

a comparison module adapted to;

compare the difference signal to first and second threshold values,

cause the system to 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

cause the system to 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.

10. The system of claim 7, the channel controller including:

a visible light magnitude module adapted 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

a comparison module adapted to;

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

cause the system to 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

cause the system to 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.

11. The system of claim 7, further comprising:

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

a lighting controller adapted 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.

12. The system of claim 7, each of the plurality of combination light photodetectors comprising a first portion and a second portion stacked in the height direction, wherein:

the first portion has a lengthwise by widthwise first cross-sectional area;

the second portion has a lengthwise by widthwise second cross-sectional area; and

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

13. The system of claim 12, 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 height direction.

14. A method for operating a system including an image sensor for capturing both visible light images and infrared light images, comprising the steps of:

generating sensor data representing light incident on the image sensor;

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

generating 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;

subtracting the visible light magnitude signal from the combination light magnitude signal to generate a difference signal;

comparing the difference signal to first and second threshold values;

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

causing the system to 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.

15. The method of claim 14, further comprising filtering the sensor data to generate output data, such that:

the output data represents red, green, and blue light incident on the image sensor, in the visible light operating mode; and

the output data represents white and infrared light incident on the image sensor, in the infrared light operating mode.

16. A method for operating a system including an image sensor for capturing both visible light images and infrared light images, comprising the steps of:

generating sensor data representing light incident on the image sensor;

generating a visible light magnitude signal from the sensor data, the visible light magnitude signal representing substantially only green light incident on the image sensor;

generating 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;

subtracting the visible light magnitude signal from the combination light magnitude signal to generate a difference signal;

comparing the difference signal to first and second threshold values;

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

causing the system to 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.

17. The method of claim 16, further comprising filtering the sensor data to generate output data, such that:

the output data represents red, green, and blue light incident on the image sensor, in the visible light operating mode; and

the output data represents green and infrared light incident on the image sensor, in the infrared light operating mode.

18. A method for operating a system including an image sensor for capturing both visible light images and infrared light images, comprising the steps of:

generating sensor data representing light incident on the image sensor;

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

comparing the visible light magnitude signal to first and second threshold values;

causing the system to switch from a visible light operating mode to an infrared light operating mode in response to the visible light magnitude signal falling below the first threshold value; and

causing the system to 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.

19. The method of claim 18, further comprising filtering the sensor data to generate output data, such that:

the output data represents red, green, and blue light incident on the image sensor, in the visible light operating mode; and

the output data represents white and infrared light incident on the image sensor, in the infrared light operating mode.

20. The method of claim 18, further comprising filtering the sensor data to generate output data, such that:

the output data represents red, green, and blue light incident on the image sensor, in the visible light operating mode; and

the output data represents green and infrared light incident on the image sensor, in the infrared light operating mode.