Fog detecting apparatus for use in vehicle

• US 4,636,643 A
• Filed: 07/25/1984
• Issued: 01/13/1987
• Est. Priority Date: 07/25/1983
• Status: Expired due to Term

• Current Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Original Assignee: Nippondenso Co., Ltd. (DENSO Corporation)
• Inventors: Kurahashi, Takashi, Nakamura, Kanehito, Ishikawa, Hiroshi, Matsui, Kazuma
• Primary Examiner(s): FIELDS, CAROLYN
• Application Number:
  US06/634,360
• Time in Patent Office: 902 Days
• Field of Search: 250/341, 250/338, 250/339, 250/349, 356/445, 356/448, 219/203, 318/483
• US Class Current: 250/338.1
• CPC Class Codes: B60S 1/0818 including control systems responsive to external conditions, e.g. by detection of moisture, dirt or the like
• CPC Class Codes: B60S 1/0837 with a particular arrangement of the optical elements
• CPC Class Codes: B60S 1/0874 characterized by the position of the sensor on the windshield
• CPC Class Codes: G01N 21/35 using infrared light G01N21/39 takes precedence
• CPC Class Codes: G01N 21/3554 for determining moisture content
• CPC Class Codes: G01N 21/55 Specular reflectivity

Abstract

In a fog detecting apparatus with optoelectronic system, comprising infrared-emitting means and infrared-receiving means, is provided means for adjusting a reference which is compared with a voltage value of a detecting signal generated according to an electrical signal produced by the infrared-receiving means in order to distinguish whether a windshield of a vehicle is in the fogging condition or not. The reference is changed according to the detecting signal which is produced when the windshield is in good condition against the fogging after a fog removing apparatus has been actuated to remove the fog attached on the windshield, so that the fogging condition is detected in accuracy independently of the contamination of the optoelectronic system or the like.

Claims

1. A fog detecting apparatus for use in a vehicle, comprising:

(a) means for emitting an infrared beam such that the emitted infrared beam is directed to a predetermined portion of a wndshield of said vehicle, said infrared-emitting means being actuated in response to a signal applied thereto from an emitting control circuit;

(b) means for receiving an infrared beam reflected at said predetermined portion, said infrared-receiving means producing an electrical signal corresponding to an intensity of an infrared beam reaching said infrared-receiving means after a reflection;

(c) means for detecting a fog on said windshield by comparing said electrical signal from said infrared-receiving means with a predetermined reference value and issuing a command signal indicative of the removal of the fog in response to the detection of the fog;

(d) first decision means for deciding that the fluctuation of said electrical signal is stably kept within a first predetermined range, after the removal of the fog performed in response to said command signal;

(e) second decision means for deciding that the deviation between said electrical signal and said predetermined reference value remains within a second predetermined range, after the decision of stability of the fluctuation; and

(f) means for updating said predetermined reference value with a value of said electrical signal at the time that a decision is made by said second decision means.

2. A fog detecting apparatus as claimed in claim 1, further comprising means for causing the updating of said predetermined reference value to be prohibited when the deviation is beyond said second predetermined range.

3. A fog detecting apparatus as claimed in claim 1, further comprising means for causing the updated reference value to be retained irrespective of the turn-off of a key switch of said vehicle.

4. A fog detecting apparatus for use in a vehicle, comprising:

(a) means for emitting an infrared beam such that the emitted infrared beam is directed to a predetermined portion of a windshield of said vehicle, said infrared-emitting means being actuated in response to a signal applied thereto from an emitting control circuit;

(b) means for receiving an infrared beam reflected at said predetermined portion, asid infrared-receiving means producing an electrical signal coresponding to an intensity of an infrared beam reaching said infrared-receiving means after a reflection;

(c) means for detecting a fog on said windshield by comparing said electrical signal from said infrared-receiving means with a predetermined reference value and issuing a command signal indicative of the removal of the fog to actuate a fog removing apparatus provided in said vehicle in response to the direction of the fog;

(d) a timer circuit responsive to said command signal issuing means for causing said fog removing apparatus to continuously operate for a predetermined period of time after the absence of said command signal;

(e) first decision means for deciding that the fluctuation of said electrical signal is stably kept within a first predetermined range, after the removal of the fog performed in response to said command signal;

(f) second decision means for deciding that the deviation between said electrical signal and said predetermined reference value remains within a second predetermined range, after the decision of stability of the fluctuation; and

(g) means for updating said predetermined reference value with a value of said electrical signal at the time that a decision is made by said second decision means.

5. A fog detecting apparatus for use in a vehicle, comprising:

(a) a plurality of infrared-emitters for emitting infrared beams such that the emitted infrared beams are respectively directed to a plurality of predetermined portions of a windshield of said vehicle, each of said infrared-emitter being actuated in response to a signal applied thereto from an emitting control circuit;

(b) a plurality of infrared receivers for receiving infrared beams reflected at said predetermined portions, each of said infrared-receivers producing an electrical signal corresponding to an intensity of an infrared beam reaching said infrared-receivers after a reflection;

(c) a plurality of detectors, each for detecting a fog on said windshield by comparing each of said electrical signals from each of said infrared-receivers with a predetermined reference value and issuing an command signal indicative of the presence of the fog in response to the detection of the fog;

(d) an OR circuit coupled to each of said detectors for generating a signal for actuating a fog removing apparatus provided in said vehicle in response to at least one command signal from said plurality of detectors;

(e) first decision means for deciding that the fluctuation of each of said electrical signals is stably kept within a first predetermined range, after the removal of the fog performed in response to said signal from said OR circuit;

(f) second decision means for deciding that the deviation between each of said electrical signals and said predetermined reference value remains within a second predetermined range, after the decision of stability of the fluctuation; and

(g) means for updating said predetermined reference value with a value of one of said electrical signals at the time that a decision is made by said second decision means.