Method for fast judging and optimizing light emitting quality of light guide plate based on image processing technology

Abstract

The present invention discloses a method for fast judging and optimizing light emitting quality of a light guide plate based on an image processing technology. According to the method, an illuminance diagram of the light guide plate is regarded as a single-color image, illuminance information is converted into a gray level, gray levels of all pixel points are calculated through a gray level histogram, the light outgoing quality of the light guide plate is analyzed according to a discrete degree of the gray levels, positions of the gray levels discrete in distribution in the gray level histogram on the illuminance diagram are found out through programming, a net point filling rate in a corresponding area is directly optimized and is eliminated, and a uniformity degree evaluation formula with a precision P judgment criterion is given. The present invention effectively improves the optimizing efficiency of the light guide plate, and an optimized result is closer to an actual visual effect.

Claims

1. A method comprising: acquiring a spatial distribution of luminous emittance from a light guide plate as a grayscale image; compiling a histogram of intensity values of pixels of the grayscale image; identifying pixels based on their intensity values in the histogram; and reducing a range of the intensity values of the identified pixels by altering optical structures of the light guide plate at locations corresponding to the identified pixels.

2. The method according to claim 1, further comprising evaluating uniformity of the luminous emittance from the light guide plate using a formula: $U=\underset{g=g_m-P}{\overset{g_m+P}{.Math.}}\frac{N_g}{N}$ wherein Ng is a number of the pixels whose intensity values are g, N is a total number of the pixels, U is a measure of the uniformity, and g.sub.m is a gray level at the peak.

3. The method according to claim 1, wherein altering the optical structures comprises adjusting a spacing, a size, a shape or a density of net points on the light guide plate.

4. The method according to claim 3, wherein the net points have a shape of a conical frustum, a sphere or a cone.

Description

BRIEF DESCRIPTION OF FIGURES

(1) FIG. 1 is a model schematic diagram of a light guide plate used by the present invention;

(2) FIG. 2 is a spatial distribution of luminous emittance before optimization;

(3) FIG. 3 is a gray level histogram obtained from the spatial distribution of luminous emittance before optimization;

(4) FIG. 4 is a spatial distribution of luminous emittance after optimization; and

(5) FIG. 5 is a gray level histogram obtained from the spatial distribution of luminous emittance after optimization.

(6) In the figures: 1net points, 2light guide plate, 3LED light source, 4detecting screen.

DETAILED DESCRIPTION

(7) In order to elaborate the present invention in detail, the following is illustrated in conjunction with drawings. But examples taken as examples below are only used for explaining a method of the present invention, and cannot be used for judging or limiting its range of application.

Example

(8) FIG. 1 is a model diagram used by the present invention in a simulating process. modeling is performed on a light guide plate 2 with net points having a shape of a conical frustum as an example, wherein a light source is an LED light source 3, a detecting screen 4 is added above a light outgoing surface, and luminous emittance information is detected so that a spatial distribution of luminous emittance as shown in FIG. 2 is obtained. A gray level histogram represents luminous emittance information as shown in FIG. 3, a finally optimized spatial distribution of luminous emittance is as shown in FIG. 4, and a gray level histogram after optimization is as shown in FIG. 5.

(9) A method for fast judging and optimizing luminous quality of a light guide plate based on an image processing technology includes the following specific steps:

(10) 1. Modeling is performed by ray tracing software, wherein as shown in FIG. 1, the LED light sources 3 are arranged on one side of the light guide plate 2, the detecting screen 4 is added above the light outgoing surface, the net points having the shape of the conical frustum are arranged on a bottom surface, and initial ray tracing is performed.

(11) 2. A spatial distribution of luminous emittance of the light guide plate before optimization as shown in FIG. 2 is obtained. By software evaluation, a uniformity of luminous emittance is 56.6%, and luminous efficacy is 46.2%. The spatial distribution of luminous emittance is converted into a grayscale image, a histogram of intensity values of pixels of the grayscale image is compiled, and then certain pixels are identified based on their intensity values in the histogram, as shown in FIG. 3. At this time, a gray level at the peak is g.sub.m=148, and when P=20, according to a formula for evaluating a uniformity of luminous emittance, U=27.6%, and a gray level distribution range is 147.

(12) 3. On the basis of FIG. 3, a range of the intensity values of the identified pixels is reduced by altering the net points of the light guide plate at locations corresponding to the identified pixels. Then, a spatial distribution of luminous emittance after optimization as shown in FIG. 4 is obtained. By software evaluation, the uniformity of luminous emittance reaches 93%, and the luminous efficacy is 66.5%. In the gray level histogram of FIG. 5, g.sub.m=227, and when P=20, U=90.3%, and a gray level distribution range is 90. Compared with before optimization, the luminous efficacy is improved by 20.3%, the uniformity is improved by 62.7%, and the gray level distribution range is reduced by 57.

(13) Further, a size of the light guide plate in step 1 is 184*314*0.55 mm.sup.3.

(14) Further, the ray tracing software in step 1 is any one in TracePro and Lightools.

(15) It needs to be noted that the spatial distribution of luminous emittance may be an image obtained by software simulation, or other detecting elements such as a CCD (Charge-Coupled Device).

(16) The basic principle, main characteristics and advantages of the present invention are displayed and described above. What is described in the above example and the description only explains the principle of the present invention, on a premise without breaking away from spirit and a scope of the present invention, the present invention can also have various changes and improvements, and the changes and improvements all fall into the protective scope of the present invention. The protective range of the present invention is defined by attached claims and its equivalents.