Time, space, and/or wavelength multiplexed capacitive light sensor, and related methods

• US 20080234895A1
• Filed: 03/14/2008
• Published: 09/25/2008
• Est. Priority Date: 01/10/2006
• Status: Active Grant

• Current Assignee: Guardian Glass LLC (KOCH Industries Incorporated)
• Original Assignee: Guardian Industries Corporation (KOCH Industries Incorporated)
• Inventors: Veerasamy, Vijayen S.
• Granted Patent: US 8,634,988 B2
• Time in Patent Office: Days
• US Class Current: 701/36
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10174 Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
• CPC Class Codes: B32B 17/10761 containing vinyl acetal
• CPC Class Codes: B60Q 1/1423 Automatic dimming circuits, i.e. switching between high beam and low beam due to change of ambient light or light level in road traffic
• CPC Class Codes: B60Q 2300/112 Vehicle speed
• CPC Class Codes: B60Q 2300/312 Adverse weather
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0825 Capacitive rain sensor
• CPC Class Codes: B60S 1/087 including an ambient light sensor control of vehicle lights B60Q
• CPC Class Codes: G01D 5/24 by varying capacitance

Abstract

In certain example embodiments, techniques for operating vehicle lights are provided. A capacitive light sensor is configured to sense a presence and intensity of light over at least one wavelength, with each said wavelength being associated with a respective output channel of the light sensor. A buffer is filled with data from the at least one output channel, with the buffer being filled with a predetermined number of data points at a predetermined frequency. An edge change is detected in the data in the buffer. An on/off state of the vehicle lights is maintained when an edge change is not detected. When an edge change is detected, when the data passes from a high value to a low value through a first predefined threshhold and remains lower than the first predefined threshold for a persistence interval, the vehicle lights are turned on, and when the data passes from a low value to a high value through a second predefined threshold and remains higher than the second predefined threshold value for the persistence interval, the vehicle lights are turned off. The second threshold is equal to the first threshold plus a hysteresis factor. The capacitive light sensing approaches of certain example embodiments may be time, space, and/or wavelength multiplexed.

Claims

1. A method of operating vehicle lights, the method comprising:

providing a capacitive light sensor configured to sense a presence and intensity of light over at least one wavelength, each said wavelength being associated with a respective output channel of the light sensor;

filling a buffer with data from the at least one output channel, the buffer being filled with a predetermined number of data points at a predetermined frequency;

detecting an edge change in the data in the buffer;

maintaining an on/off state of the vehicle lights when an edge change is not detected; and

when an edge change is detected;

when the data passes from a high value to a low value through a first predefined threshold and remains lower than the first predefined threshold for a persistence interval, turning on the vehicle lights, and

when the data passes from a low value to a high value through a second predefined threshold and remains higher than the second predefined threshold value for the persistence interval, turning off the vehicle lights,

wherein the second threshold is equal to the first threshold plus a hysteresis factor.

2. The method of claim 1, wherein the buffer is a FIFO buffer.

3. The method of claim 1, wherein the predetermined frequency is about 25 Hz.

4. The method of claim 3, wherein the predetermined number of data points is 50.

5. The method of claim 1, wherein the first threshold is about 2,500 lux.

6. The method of claim 1, wherein the high value is at least about 4,000 lux.

7. The method of claim 1, wherein the low value is less than or equal to about 1,000 lux.

8. The method of claim 1, wherein the persistence interval corresponds with the predetermined frequency.

9. The method of claim 1, wherein the hysteresis factor is equal to about 5,000 lux.

10. The method of claim 1, further comprising:

determining a speed of the vehicle; and

when the vehicle speed exceeds a first speed threshold, adding a predefined speed hysteresis factor to the first and second thresholds until the vehicle speed drops below a second speed threshold.

11. The method of claim 10, wherein the first speed threshold is equal to about 100 km per hour,

wherein the second speed threshold is equal to about 30 km per hour, and

wherein the speed hysteresis factor is equal to about 1,000 lux.

12. The method of claim 1, wherein the at least one channel is a broadband channel that operates over a wavelength of from about 300 nm to about 1100 nm and peaks in responsivity at about 650 nm.

13. The method of claim 1, wherein the capacitive light sensor is configured to sense a presence and intensity of light over three wavelengths and output data respectively on first, second, and third channels,

wherein the first channel is a broadband channel that operates over a wavelength of from about 300 nm to about 1100 nm and peaks in responsivity at about 650 nm,

wherein the second channel is an IR light channel that operates over a wavelength of from about 500 nm to about 1100 nm and peaks in responsivity at about 800 nm, and

wherein the third channel is a visible light channel that operates over a wavelength of from about 400 nm to about 550 nm and peaks in responsivity at about 500 nm.

14. The method of claim 13, further comprising correlating changes in at least two of the first, second, and third channels;

and

changing the on/off state of the vehicle lights in dependence on the correlation.

15. The method of claim 13, further comprising turning on the vehicle lights when changes in the first and second channels are correlated;

maintaining the on/off state of the vehicle lights when the first channel indicates a change and the second channel does not indicate a change; and

turning on the vehicle lights when the third channel indicates a change and the second channel does not indicate a change.

16. The method of claim 1, further comprising mounting the light sensor to a window of the vehicle,

wherein the window is one of a vehicle windshield, a vehicle backlite, and/or a vehicle sunroof.

17. A method of operating vehicle lights, the method comprising:

providing a capacitive light sensor configured to sense a presence and intensity of light over three wavelengths, each said wavelength being respectively associated with first, second, and third output channels of the light sensor;

filling a buffer with data from the output channels, the buffer being filled with a predetermined number of data points at a predetermined frequency;

detecting an edge change in the data in the buffer;

maintaining an on/off state of the vehicle lights when an edge change is not detected;

determining a speed of the vehicle;

when the vehicle speed exceeds a first speed threshold, adding a predefined speed hysteresis factor to the first and second thresholds until the vehicle speed drops below a second speed threshold;

correlating edge changes in at least two of the first, second, and third channels; and

changing the on/off state of the vehicle lights in dependence on the correlation,

wherein the second threshold is equal to the first threshold plus a hysteresis factor.

18. The method of claim 17, wherein the first channel is a broadband channel that operates over a wavelength of from about 300 nm to about 1100 nm and peaks in responsivity at about 650 nm,

wherein the second channel is an IR light channel that operates over a wavelength of from about 500 nm to about 1100 nm and peaks in responsivity at about 800 nm, and

wherein the third channel is a visible light channel that operates over a wavelength of from about 400 nm to about 550 nm and peaks in responsivity at about 500 nm.

19. A light sensor for a vehicle, comprising:

at least one capacitive light sensor array configured to sense a presence and intensity of light over at least one wavelength, each said wavelength being associated with a respective output channel of the light sensor array;

a buffer configured to store data from the at least one output channel, the buffer being filled with a predetermined number of data points at a predetermined frequency; and

light sensing programmed logic circuitry configured to;

(a) detect an edge change in the data in the buffer, (b) maintain an on/off state of the vehicle lights when an edge change is not detected, and (c) when an edge change is detected;

when the data passes from a high value to a low value through a first predefined threshold and remains lower than the first predefined threshold for a persistence interval, generate a signal indicating that the vehicle lights are to be turned on, and when the data passes from a low value to a high value through a second predefined threshold and remains higher than the second predefined threshold value for the persistence interval, generate a signal indicate that the vehicle lights are to be turned off,

wherein the second threshold is equal to the first threshold plus a hysteresis factor.

20. A light sensor for a vehicle, comprising:

at least one capacitive light sensor array configured to sense a presence and intensity of light over a plurality of wavelengths, each said wavelength being associated with a respective output channel of the light sensor array;

a buffer configured to store data from the output channels, the buffer being filled with a predetermined number of data points at a predetermined frequency;

light sensing programmed logic circuitry configured to detect an edge change in the data in the buffer; and

speed determining programmed logic circuitry configured to determine a speed of the vehicle,

wherein the light sensing programmed logic circuitry is further configured to add a predefined speed hysteresis factor to the first and second thresholds when the vehicle speed exceeds a first speed threshold until the vehicle speed drops below a second speed threshold, correlate edge changes in at least some of the plurality of channels, and change the on/off state of the vehicle lights in dependence on the correlation, and

wherein the second threshold is equal to the first threshold plus a hysteresis factor.