Backlight module and display device

A backlight module for a display device, comprising:

• a substrate and a plurality of LED light sources disposed on the substrate following a grid pattern to form a plurality of rectangle-shaped lighting units,
• wherein each lighting unit comprises four LED light sources disposed at the lighting unit's four corners, respectively, has a length L along a first direction X and a width W along a second direction Y, and irradiates a corresponding rectangular area with the same length L and width W on an interface of the display device,
• wherein each LED light source comprises an LED and a corresponding lens disposed above the LED, the corresponding lens directing light rays emitted from the LED onto
• (1) a first corner of the corresponding rectangular area on the interface of the display device with a first luminance value E1,
• (2) a second corner of the corresponding rectangular area with luminance of zero or substantially close to zero, wherein a distance between the first corner and the second corner is L along the X direction,
• (3) a first location (x, 0) with a luminance value E (x, 0) that is determined based on a linear change of luminance value from the first luminance value E1 at the first corner to zero luminance at the second corner, wherein the first location is on a first border line between the first corner and the second corner, and x is a distance between the first location (x, 0) and the first corner along the X direction,
• (4) a third corner of the corresponding rectangular area with luminance of zero or substantially close to zero, wherein a distance between the first corner and the third corner is W along the Y direction,
• (5) a second location (0, y) with a luminance value E (0, y) that is determined based on a linear change of luminance value from the first luminance value E1 at the first corner to zero luminance at the third corner, wherein the second location is on a second border line between the first corner and the third corner, and y is a distance between the second location (0, y) and the first corner along the Y direction, and
• (6) a location (x, y) of the corresponding rectangular area with a luminance value of E (x, y) that is a product of E (x, 0) and E (0, y).