Elliptical laser probe for shadow mask
AssigneeBMC Industries, Inc.
InventorsBruce H. Zimmerman, James R. Fendley
Life of this patent
Estimating the term…
Abstract
A laser probe for measuring apertures in a sheet of material has a laser beam and a detection system. The laser beam has a major axis and a minor axis which are orthogonal to each other. The major axis is much larger than the minor axis. The dimensions of the apertures are determined from the fraction of the laser beam which passes through the sheet of material. Slot widths are measured by identifying relatively constant amounts of light passing through the sheet as the sheet moves relative to the laser beam.
Claims21
A laser probe system for measuring attributes of a sheet of material having apertures, the apertures each having widths in the direction of a first aperture axis and lengths in the direction of a second aperture axis, the first and second aperture axes orthogonal to each other, the apertures aligned in a plurality of columns along the direction of the second aperture axis, each column separated by a pitch distance, the laser probe system comprising:
- at least one probe laser beam incident on a first side of the sheet, each probe laser beam having a primary direction of propagation, a major axis in the direction of the first aperture axis and a minor axis in the direction of the second aperture axis, the major axis and minor axis normal to each other and normal to the primary direction of propagation of the probe laser beam, the major axis being larger than the sum of the width of an aperture and the pitch distance, the minor axis being smaller than the length of an aperture;
- a receiving system, positioned on the second side of the sheet, the receiving system creating a detector signal representative of the amount of light passing through the apertures in the sheet;
- and
- means for calculating an attribute of the sheet, the means for calculating being coupled to the receiving system and capable of calculating the attribute of the sheet from the detector signal produced by the receiving system.
A method for measuring widths of slots in a moving web, the moving web having columns of slots with centers, the center of each column of slots being separated from centers of other columns of slots by a horizontal pitch distance, the method comprising:
- projecting a stationary light toward the moving web, the light illuminating only a portion of the web at any one time;
- detecting the amount of light transmitted through the web;
- creating an electrical signal based on the detected light;
- identifying portions of the electrical signal which are substantially constant for a period of time, each substantially constant portion having a value;
- and
- using the value of the substantially constant portions of the electrical signal to calculate average widths of select areas of the slots through which the light passed.
A method for measuring attributes of a sheet of material having apertures, the apertures each having widths in a first aperture direction and lengths in a second aperture direction, the first and second aperture directions orthogonal to each other, the apertures aligned in relative columns along the second aperture direction, each column separated by a horizontal pitch distance in the first aperture direction, the method comprising:
- projecting at least one probe laser beam on a first side of the sheet of material, each probe laser beam having a primary direction of propagation, a major axis along the first aperture direction and a minor axis along the second aperture direction, the major axis and minor axis normal to each other and normal to the primary direction of propagation of the probe laser beam, the major axis being larger than the sum of the width of an aperture and the horizontal pitch distance, the minor axis being smaller than the length of an aperture;
- detecting the amount of light passing through the apertures in the sheet of material;
- creating a detector signal based on the amount of detected light;
- calculating from the detector signal at least one attribute of the
- sheet of material.
Dependencies are inferred from the claim text.