초록 ▼

There is provided a spread illuminating apparatus to suppress the appearance of moire fringes. A light reflection pattern of a transparent substrate is composed of grooves of substantially triangular in section and flat portions adjacent thereto. The light reflection pattern is formed substantially

There is provided a spread illuminating apparatus to suppress the appearance of moire fringes. A light reflection pattern of a transparent substrate is composed of grooves of substantially triangular in section and flat portions adjacent thereto. The light reflection pattern is formed substantially parallel to the optical axis of a bar-like light source and the depth of the grooves increases gradually in proportion to the increase in distance from the light source. The interval of the adjacent grooves (the groove interval) is set to vary irregularly. Thereby, the relation between the interval of grooves and the interval of mosaic pattern of liquid crystal cells is not definite, and the appearance of moire pattern can be suppressed. The variation ratio of the groove interval is set to range 25% to 85% of the average groove interval

대표청구항 ▼

1. A spread illuminating apparatus of side light type, comprising: a transparent substrate made of a light-transmissible material; a bar-like light source disposed along and close to an end surface of the transparent substrate; and a light reflection pattern formed on the transparent substrate,

1. A spread illuminating apparatus of side light type, comprising: a transparent substrate made of a light-transmissible material; a bar-like light source disposed along and close to an end surface of the transparent substrate; and a light reflection pattern formed on the transparent substrate, and consisting of a plurality of grooves and a plurality of flat portions adjacent thereto, wherein intervals of the grooves of the light reflection pattern are varied irregularly. 2. A spread illuminating apparatus of side light type, comprising: a transparent substrate made of a light-transmissible material; a bar-like light source disposed along and close to an end surface of the transparent substrate; and a light reflection pattern formed on the transparent substrate, and consisting of a plurality of prisms forming a stair-like configuration, wherein intervals of the prism steps of the light reflection pattern are varied irregularly. 3. The spread illuminating apparatus according to claim 1, wherein the light reflection pattern is formed so as to be parallel to the bar-like light source. 4. The spread illuminating apparatus according to claim 1, wherein the light reflection pattern is formed so as to have a predetermined angle to the bar-like light source. 5. The spread illuminating apparatus according to claim 1, wherein an ithgroove from the light source side is positioned so as to satisfy a formula: Pi=i×C+{B×(-A+Q/10)}, (i=1, 2, 3 . . . ), where Q is a random number, Pi is a distance from a predetermined point to a place where the ithgroove is positioned, C is an average interval between adjacent grooves, B is a variation adjusting value, and A is a deviation adjusting value. 6. The spread illuminating apparatus according to claim 1, wherein a variation ratio of each interval of the grooves set to be irregular is calculated by a formula: [PH={(Pmax-Ptrg)/Ptrg}×100],