LIGHT SENSOR HAVING PARTIALLY OPAQUE OPTIC

• US 20150022543A1
• Filed: 07/28/2014
• Published: 01/22/2015
• Est. Priority Date: 02/12/2013
• Status: Active Grant

• Current Assignee: Gentex Corporation
• Original Assignee: Gentex Corporation
• Inventors: Nelson, Barry K, Bechtel, Jon H, Reese, Spencer D, McMillan, Daniel G
• Granted Patent: US 9,870,753 B2
• Time in Patent Office: Days
• US Class Current: 345/589
• CPC Class Codes: B60R 1/088 using a cell of electrically changeable optical characteristic, e.g. liquid-crystal or electrochromic mirrors
• CPC Class Codes: G01J 1/26 adapted for automatic variation of the measured or reference value regulation of light intensity G05D25/00
• CPC Class Codes: G01J 1/4228 arrangements with two or more detectors, e.g. for sensitivity compensation
• CPC Class Codes: G01J 1/46 using a capacitor
• CPC Class Codes: G01J 2001/0276 Protection
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2380/10 Automotive applications
• CPC Class Codes: G09G 5/10 Intensity circuits

Abstract

A rearview assembly for a vehicle is provided that includes: a housing configured for mounting to the vehicle; a rearview element disposed in the housing that displays images of a scene exterior of the vehicle; a light sensor assembly disposed in the housing; and a controller for receiving the electrical signal of the light sensor and for adjusting a brightness of the images displayed by the rearview element. The light sensor includes a light sensor for outputting an electrical signal representing intensity of light impinging upon a light-receiving surface of the light sensor, and a secondary optical element configured to receive light, wherein the light passes through the secondary optical element to the light sensor, the secondary optical element including a tint material that is substantially color neutral for attenuating light passing therethrough.

Claims

1. A rearview assembly for a vehicle comprising:

a housing configured for mounting to the vehicle;

a rearview element disposed in said housing that presents images of a scene rearward of the vehicle;

a light sensor assembly disposed in said housing, said light sensor comprising;

a light sensor for outputting an electrical signal representing intensity of light impinging upon a light-receiving surface of the light sensor, and

a secondary optical element configured to receive light, wherein the light passes through said secondary optical element to said light sensor, said secondary optical element including a tint material that is substantially color neutral for attenuating light passing therethrough; and

a controller for receiving the electrical signal of said light sensor and for adjusting a brightness of the images presented by said rearview element.

2. The rearview assembly of claim 1, wherein said rearview element includes a display positioned in said housing, wherein the controller adjusts the brightness of the images presented by said rearview element by adjusting the brightness of said display.

3. The rearview assembly of claim 1, wherein said rearview element includes an electro-optic mirror element having a reflectance that is adjustable, wherein the controller adjusts the brightness of the images presented by said rearview element by adjusting the reflectance of said electro-optic mirror element.

4. The rearview assembly of claim 3, wherein said rearview element includes a display positioned in said housing, wherein the controller adjusts the brightness of the images presented by said rearview element by further adjusting the brightness of said display.

5. The rearview assembly of claim 1, wherein said light sensor comprises an input/output pad and a capacitor provided at the input/output pad and connected between the input/output pad and ground for blocking static electricity.

6. The rearview assembly of claim 1, wherein said light sensor comprises an input/output pad and an input low pass filter provided at an input side of the input/output pad for blocking electromagnetic interference.

7. The rearview assembly of claim 1, wherein said light sensor comprises:

an exposed light transducer operative to accumulate charge in proportion to light incident on the exposed light transducer over an integration period;

a light-to-pulse circuit in communication with the exposed light transducer, the light-to-pulse circuit operative to output a pulse having a pulse width based on the charge accumulated by the exposed light transducer; and

a bandgap reference circuit for receiving power from a power source having a supply voltage level in a range of about 3.3V to about 5.0V, and for generating a set of stable reference voltages throughout the supply voltage level range to the light-to-pulse circuit.

8. The rearview assembly of claim 1, wherein said light sensor comprises a bandgap voltage reference circuit for receiving power from a power source and for generating a set of stable reference voltages to the light-to-pulse circuit, wherein the bandgap voltage reference circuit generates constant currents from the supply voltage supplied by the power supply and wherein the bandgap voltage reference circuit comprises resistive ladders through which the constant currents are passed to generate the set of stable reference voltages.

9. The rearview assembly of claim 1, wherein said light sensor comprises:

an exposed light transducer operative to accumulate charge in proportion to light incident on the exposed light transducer over an integration period;

a shielded light transducer shielded from light, the shielded light transducer having substantially the same construction as the exposed light transducer, the shielded light transducer operative to accumulate charge in proportion to noise over the integration period; and

a light-to-pulse circuit in communication with the exposed light transducer and the shielded light transducer, the light-to-pulse circuit operative to output a pulse having a pulse width based on the difference between the charges accumulated by the exposed and shielded light transducers, wherein the light-to-pulse circuit includes a one shot logic circuit that contributes to a generation of the pulse.

10. The rearview assembly of claim 1, wherein said light sensor comprises:

an enclosure having a window for receiving light, the enclosure admitting at least a power connection pad, a ground connection pad, and an input/output pad;

an exposed light transducer disposed within the enclosure, the exposed light transducer operative to accumulate charge in proportion to light received through the window incident on the exposed light transducer over an integration period;

a light-to-pulse circuit in communication with the exposed light transducer, the light-to-pulse circuit operative to output a pulse on the output pin, the pulse width based on the charge accumulated by the exposed light transducer over the integration period; and

a nonvolatile memory within the enclosure for storing data from which calibration data may be obtained for the light sensor.

11. A display assembly for a vehicle comprising:

a housing configured for mounting to the vehicle;

a display element disposed in said housing that displays images of a scene exterior of the vehicle;

a light sensor assembly disposed in said housing, said light sensor comprising;

a light sensor for outputting an electrical signal representing intensity of light impinging upon a light-receiving surface of the light sensor, and

a secondary optical element configured to receive light, wherein the light passes through said secondary optical element to said light sensor, said secondary optical element including a tint material that is substantially color neutral for attenuating light passing therethrough; and

a controller for receiving the electrical signal of said light sensor and for adjusting a brightness of the images displayed by said display element.

12. The display assembly of claim 11, wherein said light sensor comprises:

an exposed light transducer operative to accumulate charge in proportion to light incident on the exposed light transducer over an integration period;

a light-to-pulse circuit in communication with the exposed light transducer, the light-to-pulse circuit operative to output a pulse having a pulse width based on the charge accumulated by the exposed light transducer; and

a bandgap reference circuit for receiving power from a power source having a supply voltage level in a range of about 3.3V to about 5.0V, and for generating a set of stable reference voltages throughout the supply voltage level range to the light-to-pulse circuit.

13. The display assembly of claim 11, wherein said light sensor comprises a bandgap voltage reference circuit for receiving power from a power source and for generating a set of stable reference voltages to the light-to-pulse circuit, wherein the bandgap voltage reference circuit generates constant currents from the supply voltage supplied by the power supply and wherein the bandgap voltage reference circuit comprises resistive ladders through which the constant currents are passed to generate the set of stable reference voltages.

14. The display assembly of claim 11, wherein said light sensor comprises:

an exposed light transducer operative to accumulate charge in proportion to light incident on the exposed light transducer over an integration period;

a shielded light transducer shielded from light, the shielded light transducer having substantially the same construction as the exposed light transducer, the shielded light transducer operative to accumulate charge in proportion to noise over the integration period; and

a light-to-pulse circuit in communication with the exposed light transducer and the shielded light transducer, the light-to-pulse circuit operative to output a pulse having a pulse width based on the difference between the charges accumulated by the exposed and shielded light transducers, wherein the light-to-pulse circuit includes a one shot logic circuit that contributes to a generation of the pulse.

15. The display assembly of claim 11, wherein said light sensor comprises:

an enclosure having a window for receiving light, the enclosure admitting at least a power connection pad, a ground connection pad, and an input/output pad;

an exposed light transducer disposed within the enclosure, the exposed light transducer operative to accumulate charge in proportion to light received through the window incident on the exposed light transducer over an integration period;

a light-to-pulse circuit in communication with the exposed light transducer, the light-to-pulse circuit operative to output a pulse on the output pin, the pulse width based on the charge accumulated by the exposed light transducer over the integration period; and

a nonvolatile memory within the enclosure for storing data from which calibration data may be obtained for the light sensor.

16. A light sensor package comprising:

an enclosure having a window for receiving light, the enclosure admitting at least a power connection pad, a ground connection pad, and an input/output pad;

an exposed light transducer disposed within the enclosure, the exposed light transducer operative to accumulate charge in proportion to light received through the window incident on the exposed light transducer over an integration period;

a light-to-pulse circuit in communication with the exposed light transducer, the light-to-pulse circuit operative to output a pulse on the output pin, the pulse width based on the charge accumulated by the exposed light transducer over the integration period; and

a nonvolatile memory within the enclosure for storing data from which calibration data may be obtained for the light sensor.

17. The light sensor package of claim 16, wherein the calibration data includes calibration data for the integration periods and offsets.

18. The light sensor package of claim 16, wherein the data stored in the nonvolatile memory is the calibration data.

19. The light sensor package of claim 16, wherein the data stored in the nonvolatile memory is a serial number with which the calibration data is associated.

20. A rearview assembly for a vehicle comprising:

a rearview device for providing a rearward view to a driver of the vehicle;

the light sensor of claim 16; and

a mounting mechanism adapted for mounting the rearview device and the light sensor to the vehicle.