Water drop detector on transparent substrate

• US 5,998,782 A
• Filed: 11/13/1998
• Issued: 12/07/1999
• Est. Priority Date: 11/14/1997
• Status: Expired due to Fees

• Current Assignee: Niles Company Limited (Valeo SE)
• Original Assignee: Nippon Sheet Glass Company Limited
• Inventors: Koyama, Tadashi, Tsunetomo, Keiji, Tanaka, Shuhei, Imanishi, Hideki
• Primary Examiner(s): Font, Frank G.
• Assistant Examiner(s): Lauchman, Layla G.
• Application Number:
  US09/191,188
• Time in Patent Office: 389 Days
• Field of Search: 250/227.24, 250/227.25, 250/227.11, 250/222.2, 250/574, 318/643, 318/483, 340/602, 340/604, 356/445
• US Class Current: 250/227.25
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0837 with a particular arrangement of the optical elements
• CPC Class Codes: B60S 1/0881 characterized by the attachment means on the windshield
• CPC Class Codes: B60S 1/0888 characterized by the attachment of the elements in a unit

Abstract

A windshield (transparent substrate) 1 having the function of detecting the presence of water drops W upon one side surface of the windshield depending upon variations in an amount of reflected light, comprising a rain sensor provided on the other side surface of the windshield, which further comprises: light emitting means 6 for guiding light into the windshield 1; light receiving means 7 for detecting the light which is reflected within the windshield 1; and, light shielding members 10 and 11 provided on the other side surface of the windshield 1 opposing the light emitting means 6 and the light receiving means 7, respectively; wherein the light shielding member 10 shields the light emitted from the light emitting means 6 at an incident angle less than a critical angle at which total internal reflection occurs at a boundary surface between air and the windshield 1, while the other shielding member 11 shields outside ambient light incident upon the light receiving means 7.

Claims

1. A water drop detector on a transparent substrate having the function of detecting the presence of liquid water upon one side surface of the transparent substrate depending upon variations in an amount of reflected light, comprising:

a sensor device provided at the other surface side of said transparent substrate, the sensor further comprising;

light emitting means for guiding light into said transparent substrate;

light receiving means for detecting the light which is reflected within said transparent substrate; and

light shielding members provided at the other surface side of said transparent substrate opposing said light emitting means and said light receiving means, respectively;

wherein

one of the light shielding members shields the light emitted from said light emitting means at an incident angle less than a critical angle at which total internal reflection occurs upon a boundary surface between ambient air and said transparent substrate, while the other of said light shielding members shields ambient light incident upon said light receiving means.

2. A water drop detector on a transparent substrate as defined in claim 1, wherein the light emitted from said light emitting means is emitted at an incident angle less than the critical angle so that total internal reflection occurs at least two times within a glass substrate comprising said sensor device, and the light which undergoes the total internal reflection within said transparent substrate enters into said light receiving means after having undergone total internal reflection at least two times within said glass substrate.