Method for adjusting positions of leds of led light bar

A method for adjusting positions of LEDs (light emitting diodes) of an LED light bar, comprising following steps:

• providing a rectangular circuit board with a plurality of LED footprints arranged on the circuit board and along a lengthwise direction of the circuit board, the circuit board having opposite first and second sides and opposite third and fourth sides wherein the first and second sides are longer than the third and fourth sides, the circuit board having a base line on the circuit board and along the lengthwise direction of the circuit board, the base line extending through a middle of the third side and a middle of the fourth side, and measuring an offset X0 between each of the LED footprints and the base line by an optical measuring device;
• providing a first flat plate and a second flat plate, the first flat plate and the second flat plate being parallel to the base line and contacted with the opposite first and second sides of the circuit board;
• and
• measuring a distance between the first flat plate and the base line by the optical measuring device, and measuring a distance between the second flat plate and the base line by the optical measuring device, an offset A between each of the LED footprints and a central axis of a space between the first and second plates being obtained by following equation:
• A=X0−(X1−X2)/2, wherein X0 represents the offset between a corresponding LED footprint and the base line, X1 represents a distance between the first flat plate and the base line, and X2 represents a distance between the second flat plate and the base line, wherein X0 is positive if X0 is measured from the base line toward the first side and X0 is negative if X0 is measured from the base line toward the second side and if A is minus an LED corresponding to the corresponding LED footprint to be actually mounted on the circuit board should be moved a distance of absolute value of A toward the first side of the circuit board and if A is positive the LED to be actually mounted on the circuit board should be moved a distance of A toward the second side of the circuit board, whereby all of the LEDs actually mounted on the circuit board are aligned with the central axis of the space between the first and second plates.