Capacitive moisture sensor system for a surveillance camera

• US 10,274,449 B2
• Filed: 10/17/2016
• Issued: 04/30/2019
• Est. Priority Date: 10/17/2016
• Status: Active Grant

• Current Assignee: Bosch Security Systems Incorporated (Robert Bosch GmbH), Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Dannan, Benjamin
• Primary Examiner(s): Phan, Huy Q
• Assistant Examiner(s): Rios Russo, Raul J
• Application Number:
  US15/295,021
• Publication Number:
  US 20180106746A1
• Time in Patent Office: 925 Days
• Field of Search: 324 7611- 7683, 324459, 324600, 324634, 324640, 324643, 324649, 324658, 324663, 324664, 324689
• CPC Class Codes: G01N 27/223 for determining moisture content, e.g. humidity rain detectors on vehicle windows B60S1/0825
• CPC Class Codes: G01R 27/26 Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
• CPC Class Codes: G01R 27/2605 Measuring capacitance capacitive sensors G01D5/24
• CPC Class Codes: H04N 23/50 Constructional details
• CPC Class Codes: H04N 23/52 Elements optimising image sensor operation, e.g. for electromagnetic interference [EMI] protection or temperature control by heat transfer or cooling elements

Abstract

An inter-digital capacitive sensor and control system are used to distinguish between rain, ice, dirt and debris on the outer lens surface of a surveillance camera. The electrodes of the capacitive sensor are made from a conductive coating such as printed epoxy or a transparent conductive oxide, that is directly deposited onto the inner surface of the lens. A defroster is spaced radially-outward from the capacitive sensor and is formed by metal deposition directly on the substrate surface.

Claims

1. A capacitive moisture sensor for a camera, comprising:

a substrate having a first surface configured to being exposed to moisture, and having a second surface opposite to the first surface, the substrate including a camera view area;

a first electrode conductively coated on the second surface of the substrate and including a conductive material, the first electrode being disposed radially outward from the camera view area;

a second electrode disposed on the second surface of the substrate and including a conductive material, the second electrode being spaced from the first electrode and being disposed radially outward from the camera view area;

a first electrical contact deposited on the second surface of the substrate and connected in circuit with the first electrode; and

a second electrical contact deposited on the second surface of the substrate and connected in circuit with the second electrode.

2. The capacitive moisture sensor of claim 1, wherein

the first electrode comprises a first plurality of fingers;

and

the second electrode comprises a second plurality of fingers spaced from the first plurality of fingers.

3. The capacitive moisture sensor of claim 2, wherein each of the fingers has a length of between 7 and 16 millimeters.

4. The capacitive moisture sensor of claim 1, further comprising:

an anti-reflective coating deposited on the second surface of the substrate.

5. The capacitive moisture sensor of claim 1, wherein the capacitive moisture sensor further comprises:

a defroster deposited onto the substrate radially outward from the camera view area.

6. The capacitive moisture sensor of claim 1, wherein the defroster includes at least one metal-containing layer disposed adjacent to more than one portion of the camera view area.

7. A method of forming a capacitive moisture sensor on a substrate for a camera, comprising:

coating a surface of the substrate with a conductive material to form a first electrode of a capacitor, the first electrode being formed radially outward from a camera view area of the substrate;

coating the surface of the substrate with a conductive material to form a second electrode of the capacitor that is spaced from the first electrode, the second electrode being formed radially outward from the camera view area of the substrate;

depositing a first electrical contact on the surface of the substrate; and

depositing a second electrical contact on the surface of the substrate.

8. The method of claim 7, further comprising:

forming the first electrode such that the first electrode has a first plurality of fingers;

and forming the second electrode such that the second electrode has a second plurality of fingers.

9. The method of claim 8, further comprising:

depositing a conductive defroster layer on the surface of the substrate.

10. The method of claim 9, further comprising:

depositing the metal-containing defroster layer radially-outward of the camera view area.