Headlight aiming method using pattern framing

• US 5,373,357 A
• Filed: 10/21/1992
• Issued: 12/13/1994
• Est. Priority Date: 02/08/1991
• Status: Expired due to Fees

• Current Assignee: Hopkins Manufacturing Corporation (Hoppy Holdings Corp.)
• Original Assignee: Hopkins Manufacturing Corporation (Hoppy Holdings Corp.)
• Inventors: Hopkins, Evan L., Yotz, Gregory A.
• Primary Examiner(s): Willis, Davis L.
• Assistant Examiner(s): Pham, Hoa Q.
• Application Number:
  US07/964,599
• Time in Patent Office: 783 Days
• Field of Search: 356/121, 356/122, 356/123, 356/153, 356/154, 356/394, 33/288, 33/335, 382/8, 382/22, 382/65, 358/101, 358/106, 358/107
• US Class Current: 356/121
• CPC Class Codes: G01M 11/064 by using camera or other imaging system for the light analysis

Abstract

A method for aiming vehicle headlights and for visually displaying the illumination patterns of the headlights using "pattern framing". The apparatus focuses the light beam on a screen and senses the intensity of the light in each cell of a matrix of cells overlying the reflected light beam with an image sensor. The apparatus generates an electrical signal for each cell indicative of the intensity of the light beam in each cell. The apparatus includes a computer for comparing at least some of the electrical signals to each other and with established criteria to determine whether the headlight is aimed within a prescribed degree of accuracy. The matrix is searched to find a row and column of points farthest away from the "hot spot" of the beam which have at least one point with a certain light intensity relationship. The row and column are compared with the established criteria to determine if the headlight is properly aimed. The apparatus describes the illumination pattern of a headlight by visually displaying at least some of the electrical signals, i.e., the light intensities and their locations, on a display. The illumination pattern can be displayed as a series of isocandela lines, or can be displayed as a simulated headlight illumination pattern on a simulated road surface. The headlight illumination pattern can be compared to a properly aimed, simulated headlight illumination pattern to indicate the necessary aiming correction.

Claims

1. A method of aiming a vehicle headlight, comprising the steps of:

projecting a light beam from a vehicle headlight onto a reflective surface,

sensing the intensity of the reflected light beam in each cell in a matrix of cells overlying the reflected light beam, wherein the matrix of cells is organized in horizontal rows and vertical columns, and generating for each cell in the matrix an electrical signal indicative of the position of the cell and the intensity of the light beam in the cell, and

comparing a sufficient number of electrical signals to determine the light intensity of the brightest cell in the beam, determining light intensity at the brightest cell, calculating at least two established light intensity levels relative to the intensity of the brightest cell, and scanning rows and columns of cells to determine the location of a row having at least one cell with one of said two intensity levels, and the location of a column having at least one cell with the other of said two established light intensity levels.

2. The method as in claim 1, further including the steps of:

determining the location of the intersection of two orthogonal axes passing through the found row and column,

comparing the location of the intersection of the two orthogonal axes with established criteria for the intersection of orthogonal axes for a properly aimed headlight,

displaying the two orthogonal axes on a display along with two reference orthogonal axes which correspond to positions on a road surface, and

adjusting the vehicle headlight until the intersection of the two orthogonal axes corresponds to the intersection of the two reference orthogonal axes.

3. A method as in claim 2, wherein the cells in the matrix are scanned above and to the right of the brightest cell in the matrix for a left-hand drive vehicle headlight, and above and to the left of the brightest cell in the matrix for a right-hand drive vehicle headlight, in order to determine the location of the row and column of cells having cells with the two established light intensity levels.

4. A method as in claim 3, wherein the cells in the matrix are searched until a row is found farthest away from the row with the brightest cell having at least one cell with a light intensity value which is 20% of the light intensity value of the brightest cell, and until a column is found farthest away from the column with the brightest cell having at least one cell with a light intensity value which is 60% of the light intensity value of the brightest cell.

5. A method as in claim 3, wherein the location of the brightest intensity cell in the matrix is determined, and the rows of the matrix are then scanned by initially shifting a predetermined number of rows away from the row containing the brightest intensity cell and scanning the rows in a direction toward the row containing the brightest intensity cell until the first row is found having at least one cell with the one of the two established light intensity values, and

the columns of the matrix are scanned by initially shifting a predetermined number of columns away from the column containing the brightest intensity cell and scanning the columns in a direction toward the column containing the brightest intensity cell until the first column is found having at least one cell with the second of the two light intensity values.

6. A method as in claim 5, further including cursors moveable with respect to the vertical and horizontal axes to indicate the relative deviation of the vehicle headlight light beam and the properly aimed headlight light beam.

7. A method as in claim 3, wherein the location of the brightest intensity cell in the matrix is determined, and the rows of the matrix are then scanned by scanning the rows in a direction away from the row containing the brightest intensity cell until the row is found having at least one cell with the one of the two established light intensity values which is farthest away from the row containing the brightest intensity value, and

the columns of the matrix are scanned by scanning the columns in a direction away from the column containing the brightest intensity cell until the column is found having at least one cell with the second of the two light intensity values which is farthest away from the column containing the brightest intensity value.

8. A method as in claim 1, further including the steps of displaying graduated axes to indicate the relative deviation of the vehicle headlight light beam and a properly aimed headlight light beam, one of said axes extending vertically with respect to the headlight light beams and another of said axes extending horizontally with respect to the headlight light beams.

9. The method as in claim 8, further including the steps of:

determining the location of the intersection of the two orthogonal axes passing through the found row and column with the established light intensity level,

comparing the location of the intersection of the two orthogonal axes with established criteria for the intersection of orthogonal axes for a properly aimed headlight,

displaying the two orthogonal axes on a display along with two reference orthogonal axes which correspond to positions on a road surface, and

adjusting the vehicle headlight until the intersection of the two orthogonal axes corresponds to the intersection of the two orthogonal axes for the properly aimed headlight.

10. A method as in claim 9, wherein the cells in the matrix are scanned above and to the right of the brightest cell in the matrix for a left-hand drive vehicle headlight, and above and to the left of the brightest cell in the matrix for a right-hand drive vehicle headlight, in order to determine the location of the row and column of cells having cells with the two established light intensity levels.

11. A method as in claim 10, wherein the cells in the matrix are searched until a row is found farthest away from the row with the brightest cell having at least one cell with a light intensity value which is 20% of the light intensity value of the brightest cell, and until a column is found farthest away from the column with the brightest cell having at least one cell with a light intensity value which is 60% of the light intensity value of the brightest cell.

12. A method as in claim 10, wherein the location of the brightest intensity cell in the matrix is determined, and the rows of the matrix are then scanned by initially shifting a predetermined number of rows away from the row containing the brightest intensity cell and scanning the rows in a direction toward the row containing the brightest intensity cell until the first row is found having at least one cell with the one of the two established light intensity values, and

the columns of the matrix are scanned by initially shifting a predetermined number of columns away from the column containing the brightest intensity cell and scanning the columns in a direction toward the column containing the brightest intensity cell until the first column is found having at least one cell with the second of the two light intensity values.

13. A method as in claim 9, wherein the location of the brightest intensity cell in the matrix is determined, and the rows of the matrix are then scanned by scanning the rows in a direction away from the row containing the brightest intensity cell until the row is found having at least one cell with the one of the two established light intensity values which is farthest away from the row containing the brightest intensity value, and

the columns of the matrix are scanned by scanning the columns in a direction away from the column containing the brightest intensity cell until the column is found having at least one cell with the second of the two light intensity values which is farthest away from the column containing the brightest intensity value.

14. The method as in claim 1, further including the step of centering the headlight relative to the reflective surface with a centering device.

15. A method of aiming a vehicle headlight, comprising the steps of:

projecting a light beam from a vehicle headlight onto a reflective surface,

sensing the intensity of the projected light beam in each cell in a matrix of cells overlying the reflected light beam and generating for each cell an electrical signal indicative of the position of the cell and the intensity of the light beam in the cell,

comparing a sufficient number of electrical signals to determine the light intensity of the brightest cell in the beam, determining light intensity at the brightest cell, calculating at least two established light intensity levels relative to the intensity of the brightest cell, and scanning rows and columns of cells to determine the location of a row having at least one cell with one of said two intensity levels which is farthest away from the row with the brightest cell, and the location of a column having at least one cell with the other of said two light intensity levels which is farthest away from the column with the brightest cell, and

displaying at least some of the electrical signals as a simulated light beam to visually describe the light intensity pattern of the vehicle headlight on a simulated road surface.

16. A method of aiming a vehicle headlight, comprising the steps of:

projecting a light beam from a vehicle headlight onto a reflective surface,

sensing the intensity of the projected light beam in each cell in a matrix of cells overlying the reflected light beam and generating for each cell an electrical signal indicative of the position of the cell and the intensity of the light beam in the cell,

comparing a sufficient number of electrical signals to determine the light intensity of the brightest cell in the beam, determining light intensity at the brightest cell, calculating at least two established light intensity levels relative to the intensity of the brightest cell, and scanning rows and columns of cells to determine the location of a row having at least one cell with one of said two intensity levels which is farthest away from the row with the brightest cell, and the location of a column having at least one cell with the other of said two established light intensity level which is farthest away from the column with the brightest cell, and

displaying at least some of the electrical signals on a display to describe the light intensity pattern of the headlight, and

adjusting the aim of the headlight in accordance with the selected aiming criteria, and concurrently displaying the adjusted vehicle headlight intensity pattern on the display.

17. A method of aiming a vehicle headlight, comprising the steps of:

projecting a light beam from a vehicle headlight onto a surface,

sensing the intensity of the light beam in each cell in a matrix of cells overlying the light beam, wherein the matrix of cells is organized in horizontal rows and vertical columns, and generating for each cell in the matrix an electrical signal indicative of the position of the cell and the intensity of the light beam in the cell,

comparing a sufficient number of electrical signals to determine the light intensity of the brightest cell in the beam, determining light intensity at the brightest cell, calculating two established light intensity levels relative to the intensity of the brightest cell, scanning rows and columns of cells to determine the location of a row which is farthest away from the row with the brightest cell which has at least one cell with one of said two intensity levels, and the location of a column which is farthest away from the column of the brightest cell having at least one cell with the other of said two established light intensity levels,

determining the location of the intersection of two orthogonal axes passing through the found row and column,

comparing the location of the intersection of the two orthogonal axes with established criteria for the intersection of orthogonal axes for a properly aimed headlight,

displaying the two orthogonal axes on a display along with two reference orthogonal axes which correspond to positions on a road surface, and

adjusting the vehicle headlight until the intersection of the two orthogonal axes corresponds to the intersection of the two reference orthogonal axes.