Electro-optical rain detector for windshields

• US 4,701,613 A
• Filed: 11/12/1985
• Issued: 10/20/1987
• Est. Priority Date: 11/09/1984
• Status: Expired due to Fees

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Watanabe, Takashi, Tsuda, Nobuo, Tomikawa, Inao
• Primary Examiner(s): LaRoche, Eugene R.
• Assistant Examiner(s): Mis, David
• Application Number:
  US06/796,767
• Time in Patent Office: 707 Days
• Field of Search: 250/577, 250/227, 340/602, 350/96.19, 73/293
• US Class Current: 340/602
• 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 1/0888 characterized by the attachment of the elements in a unit
• CPC Class Codes: G01N 21/43 by measuring critical angle

Abstract

An electro-optical liquid detector assembly comprises a support block having a flat front surface attached to the internal surface of a wind-shield and being formed therein with a pair of inclined bores opening toward the internal surface of the wind-shield, a transparent flat plate contained within the support block and fixed to the support block to form a common flat front surface with the support block, the transparent flat plate being formed in its rear surface with a pair of spaced v-grooved portions which are opposed to the inclined bores, a light emitting element disposed within one of the inclined bores to emit a beam of light into the wind-shield through one of the v-grooved portions of the flat plate so as to cause internal reflection of the beam between the external and internal surfaces of the wind-shield, and a light receiving element disposed within the other inclined bore to receive the incident beam reflected by the external surface of the wind-shield through the other v-grooved portion of the flat plate so as to produce an electric signal indicative of an amount of the incident beam.

Claims

1. An electro-optical rain detector assembly comprising:

a support block having a flat front surface attached to the internal surface of a wind-shield at a portion where the external surface of said wind-shield is wiped by a wiper blade, said support block being formed therein with a pair of spaced inclined bores opening toward the internal surface of said wind-shield;

a transparent flat plate fixedly coupled within a corresponding recess in said support block to form a common flat front surface with said support block, said transparent flat plate being formed in a rear surface thereof with a pair of spaced v-grooved portions which are opposed to the inclined bores in said support block;

a light emitting element disposed within one of the inclined bores in said support block to emit a beam of light into said wind-shield through one of the v-grooved portions of said transparent flat plate so as to cause internal reflection of the beam between the external and internal surfaces of said wind-shield; and

a light receiving element disposed within the other inclined bore in said support block to receive the incident beam reflected by the external surface of said wind-shield through the other v-grooved portion of said transparent flat plate so as to produce an electric signal indicative of an amount of the incident beam;

one of said v-grooved portions having a plurality of elongated parallel oblique planar regions disposed perpendicular to the light emission axis of said light emitting element and a plurality of elongated parallel oblique planar regions disposed in parallel with said light emission axis, and the other of said v-grooved portions having a plurality of elongated parallel oblique planar regions disposed perpendicular to the light receiving axis of said light receiving element and a plurality of elongated parallel oblique planar regions disposed in parallel with said light receiving axis.

2. An electro-optical rain detector assembly as claimed in claim 1, wherein a reflection thin plate is secured to the rear surface of said transparent flat plate located between said v-grooved portions to effect multiple internal reflection of the beam in said wind-shield.

3. An electro-optical rain detector assembly as claimed in claim 1, wherein said support block and transparent flat plate are adhered to the internal surface of said wind-shield at the common flat front surface thereof.

4. An electro-optical rain detector assembly as claimed in claim 1, wherein said transparent flat plate is made of transparent synthetic resin.

5. An electro-optical rain detector assembly for detecting an adhereence condition of raindrops on the external surface of a wind-shield, comprising:

a support block having a flat front surface attached to the internal surface of said wind-shield at a portion where the external surface of said wind-shield is wiped by a wiper blade, said support block being formed therein with a pair of spaced inclined bores opening toward the internal surface of said wind-shield;

a transparent flat plate fixedly coupled within a corresponding recess in said support block to form a common flat front surface with said support block, said transparent flat plate being formed in a rear surface thereof with a pair of spaced v-grooved portions which are opposed to the inclined bores in said support block;

a transparent elastic flat plate adhered to the common flat front surface of said transparent flat plate;

at least one light emitting element disposed within one of the inclined bores in said support block to emit a beam of light into said wind-shield through one of said v-grooved portions of said transparent flat plate so as to cause internal reflection of the beam between the external and internal surfaces of said wind-shield;

at least one light receiving element disposed within the other inclined bore in said support block to receive the incident beam reflected by the external surface of said wind-shield through the other v-grooved portion of said transparent flat plate so as to produce an electric signal indicative of an amount of the incident beam; and

a frame member fixedly mounted on a stationary structure adjacent said wind-shield to support said support block thereon and press said support block toward the internal surface of said wind-shield through said elastic flat plate.

6. An electro-optical rain detector assembly as claimed in claim 5, wherein:

said at least one light emitting element comprises a plurality of light emitting elements disposed in parallel within one of the inclined bores in said support block to emit plural beams of light into said wind-shield through the one of said v-grooved portions; and

said at least one light receiving element comprises a plurality of light receiving elements disposed in parallel within the other inclined bore in said support block to receive the incident beams reflected by the external surface of said wind-shield through the other v-grooved portion.

7. An electro-optical rain detector assembly as claimed in claim 5, further comprising:

a thrust plate engaged with a rear portion of said support block and pressed toward said wind-shield by means of an adjusting screw threaded into said frame member.

8. An electro-optical rain detector assembly as claimed in claim 5, wherein:

said transparent flat plate is made of transparent synthetic resin, and said elastic flat plate is made of transparent silicone rubber.