A plurality of LEDs, each including a lens having a convex light emitting surface (or a bullet-shaped lens) and fixed to a base, are used as an outdoor display. FIGS. 5A and 5B show such a conventional LED. FIG. 5A is a top view of a conventional LED 100 having a convex lens, and FIG. 5B is a front view of the LED shown in FIG. 5A viewed from the direction Y. As shown in FIGS. 5A and 5B, the conventional LED 100 includes an LED element 20, a lead section or a lead frame 30 connected to the LED element 20, and a base 40 that supports a convex lens 50 that covers the LED element 20.
When a plurality of the LEDs 100 described above are used to form an LED display device 200, black resin material is generally provided in the gaps among the LEDs 100 in order to prevent reduction in contrast due to reflection of light from the base 40.
An example of the LED 100 with the resin material described above and the LED display device 200 is, for example, an LED described in Patent Document 1. This document describes as, conventional art, a light emitting diode lamp (light emitting diode display device) in which a plurality of LEDs, each having a convex lens, are disposed on a substrate and black resin material is injected in the gap between the LEDs.
In general, when resin material is injected into the gaps among a plurality of arranged LEDs, it is difficult to check that a desired amount of resin material (or the amount that provides an appropriate height) has been injected. In particular, if the resin material comes into contact with the convex lens (light emitting surface) when the resin material is injected, the surface tension of the resin material shapes the surface of the resin material into a meniscus at the portion where the resin material is in contact with the lens, as shown in FIG. 6. Then, the resin material 110 may cover the lens 50, which is the light emitting surface, in such a way that the height of the resin material is higher than the desired height. In this case, light emitted from the lens will be absorbed by the resin material, resulting in reduced contrast and a narrower viewing angle.
[Patent Document 1] Japanese Patent Laid-Open No. 6-85329
USPTO Backgrounds
USPTO Backgrounds