为了给液晶显示器亮度视角的设计提供依据，论文针对侧入式背光源的亮度视角进行了详细研究，考虑可能对其影响的3个因素，即灯源入光方式、导光板类型和光学膜层组配。首先，对2种不同入光方式，即短边入光和长边入光进行了研究; 接着，对3种不同类型导光板，即油墨印刷、射出成型和热滚压导光板进行了研究; 最后，对不同组配光学膜层进行了研究。测试数据显示在相同导光板和膜层组配的情况下，2种不同入光方式的二分之一亮度视角都为50°左右，但是短边入光方式在水平方向的亮度分布具有不对称性; 在相同入光方式和膜层组配的情况下，不同类型导光板的二分之一亮度视角都为50°左右，且亮度分布很一致; 在相同入光方式和导光板的情况下，不同膜层组配的二分之一亮度视角最小为27°，最大可达82°，数据变化较大。数据显示对亮度视角影响最大的因素为膜层组配，接着是入光方式，而导光板的类型对其基本没有影响。

In order to supply design rules for brightness viewing angle of liquid crystal display, this paper presents the detailed study of brightness viewing angle of side-type backlight unit. We consider that three reasons may have influence on the brightness viewing angle, which is type of light source entering light guide plate, type of light guide plate and collocation of optical film. First, short side entering type and long side entering type were studied; Second, different type of light guide plate, ink printed, injection and roll stamping light guide plate were studied; Last, different collocation of optical film were studied. Test data shows one half brightness viewing angle in horizontal direction of different entering type is about 50°under the same type of light guide plate and collocation of optical film, but short side entering type has different brightness distribution in horizontal direction. One half brightness viewing angle in horizontal direction of different light guide plate is about 50°under the same entering type and collocation of optical film, and brightness distribution in horizontal direction is almost same. The minimum value of one half brightness viewing angle is 27°, maximal value is 82°under the same entering type and light guide plate. Our study shows the main factor of brightness viewing angle is collocation of optical film, secondary factor is type of light source entering the light guide plate, and different type of light guide plate has no influence on brightness viewing angle.