Method of, and apparatus for, detecting optical axis of headlamp

• US 5,379,104 A
• Filed: 01/04/1994
• Issued: 01/03/1995
• Est. Priority Date: 01/04/1994
• Status: Expired due to Term

• Current Assignee: Chuo Electronic Measurement Co., Ltd. (Otsuka Holdings Company Limited)
• Original Assignee: Chuo Electronic Measurement Co., Ltd. (Otsuka Holdings Company Limited)
• Inventors: Takao, Osamu
• Primary Examiner(s): Rosenberger, Richard A.
• Application Number:
  US08/177,050
• Time in Patent Office: 364 Days
• Field of Search: 356/121, 33/288
• US Class Current: 356/121
• CPC Class Codes: G01M 11/064 by using camera or other imaging system for the light analysis
• CPC Class Codes: G01M 11/065 details about the image analysis

Abstract

In a method of detecting optical axis of a headlamp, according to the present invention, an image of the light projected onto the screen is segmented grid by grid on the reference grid plane, a test window set in the reference grid plane is moved and the illuminance of the light incident upon a CCD corresponding to each grid in a test window B set in the reference grid plane is integrated each time the test window B is moved, and the center of the test window C when the integrated illuminance reaches a maximum value is detected as the optical axis position. According to the present invention, it is possible to positively detect an headlamp optical axis even if a plurality of hot zones exists.

Claims

1. A method of quantitatively detecting the optical axis of a headlamp in an inspection line of vehicles such as automobiles, comprising the steps of:

picking up an image of a light emitted from a vehicle lamp under inspection and projected onto a screen placed in front of the vehicle;

forming, and storing, on a reference plane segmented into a plurality of grids a luminous intensity distribution curve corresponding to an illuminance pattern of the picked-up light image;

setting, and moving and scanning a test window occupying a predetermined area in the reference grid plane to calculate an integrated illuminance of each unit area in each test window; and

selecting and detecting as the position of the headlamp optical axis the center of the test window when the integrated illuminance reaches a maximum value.

2. A method of quantitatively detecting the optical axis of a headlamp in an inspection line of vehicles such as automobiles, comprising the steps of:

picking up an image of a light emitted from a vehicle lamp under inspection and projected onto a screen placed in front of the vehicle;

forming, and storing, on a reference plane segmented into a plurality of grids a luminous intensity distribution curve corresponding to an illuminance pattern of the picked-up light image;

setting, and moving and scanning a test window occupying a predetermined minimum area in the reference grid plane to calculate an integrated illuminance in each test window;

setting as a provisional position of the headlamp optical axis the center of the test window position when the integrated illuminance reaches a maximum value;

setting, and moving and scanning a test window occupying an area wider than the above minimum area to calculate an integrated illuminance in each test window;

setting as another provisional position of the headlamp optical axis the center of the test window position when the integrated illuminance reaches a maximum value; and

comparing these provisional positions of the headlamp optical axis with each other and determining the latter provisional position of the headlamp optical axis as the final optical axis position when the difference between the two provisional positions of the headlamp optical axis is within a permissible range.

3. A method of quantitatively detecting the optical axis of a headlamp in an inspection line of vehicles such as automobiles, comprising the steps of:

picking up an image of a light emitted from a vehicle lamp under inspection and projected onto a screen placed in front of the vehicle;

forming, and storing, on a reference plane segmented into a plurality of grids a luminous intensity distribution curve corresponding to an illuminance pattern of the picked-up light image;

setting, and moving and scanning a test window occupying a predetermined maximum area in the reference grid plane to calculate an integrated illuminance in each test window;

setting as a provisional position of the headlamp optical axis the center of the test window position when the integrated illuminance reaches a maximum value;

setting, and moving and scanning a test window occupying an area narrower than the above maximum area to calculate an integrated illuminance in each test window;

setting as another provisional position of the headlamp optical axis the center of the test window position when the integrated illuminance reaches a maximum value; and

comparing these provisional positions of the headlamp optical axis with each other and determining the former provisional position of the headlamp optical axis as the rural optical axis position when the difference between the two provisional positions of the headlamp optical axis is beyond a permissible range.

4. An apparatus for quantitatively detecting the optical axis of a headlamp in an inspection line of vehicles such as automobiles, comprising:

a means of picking up a light emitted from a vehicle lamp under inspection and projected onto a screen placed in front of the vehicle;

a means of forming, and storing, on a reference plane segmented into a plurality of grids a luminous intensity distribution curve corresponding to an illuminance pattern of the light image picked up by the imaging means; and

a means of setting, and moving and scanning a test window occupying a predetermined area in the reference grid plane to calculate an integrated illuminance in the test window while detecting the center of the test window when the integrated illuminance reaches a maximum value and to select it as the position of the headlamp optical axis.