Surface mounted device (SMD) type light emitting diode (LED) device for outdoor display screen and display module using SMD type LED device

Abstract

The invention relates to a surface mounted device (SMD) type light emitting diode (LED) device for an outdoor display screen, which comprises at least one LED chip, a lower substrate for loading the LED chips, an upper substrate combined with the lower substrate and packaging colloid arranged on the upper substrate, wherein the upper substrate is provided with steps; and the packaging colloid comprises a packaging matrix covering the steps and an optical lens arranged on the packaging matrix. In the SMD type LED device, the stepped upper substrate is combined with the packaging matrix with a certain height to reduce the size of the packaging colloid and optical loss, improve the light extraction efficiency and simplify the structure; moreover, light distribution with a wide viewing angle can be provided and the defects of a through-hole LED and a Top LED can be made up by arranging a stepped structure on the upper substrate and coving the packing colloid with a lens structure. Besides, the invention also provides a display module using the SMD type LED device for the outdoor display screen.

Description

technical field [0001] The invention relates to a light emitting diode (Light Emitting Diode, LED) and a display screen, in particular to an SMD type LED device for an outdoor display screen and a display module using the LED device. Background technique [0002] Outdoor light-emitting diode (LED) display is a new type of information display media rapidly developed in the world in the late 1980s. It is a display screen composed of dot matrix modules or pixel units composed of LEDs. Its appearance makes up for the shortcomings of the previous information release media such as magnetic flaps and neon lights, and has been widely used in railways, highways, squares and large shopping malls. [0003] Generally, outdoor display screens need to be waterproof, prevent direct sunlight, dustproof, high temperature, windproof and lightning protection, etc., so the LED devices are required to have good environmental adaptability. At present, in-line LEDs are mostly used: in-line LEDs e...

AI Technical Summary

Problems solved by technology

However, there are many defects in in-line LED products, which seriously limit the further improvement of the quality and output of outdoor display screens. The defects are as follows:

[0004] 1) Poor consistency: In the packaging and molding steps of manufacturing in-line LED devices, because the depth of the cup-shaped bracket with the LED chip inserted into the mold is difficult to control, the distance between the LED chip and the packaging lens between batches of products is prone to occur Inconsistency, which seriously affects the consistency of the product's luminous brightness and emission angle

[0005] 2) The manufacturing process is complicated and the production efficiency is low: when manufacturing outdoor display screens, because the in-line LED has pins and the pins are divided into positive and negative poles, producers usually place the in-line LED on the ground by hand. The production efficiency is low on the circuit board of the display screen; in addition, after the in-line LED is soldered on the circuit board by wave soldering, it is necessary to cut the redundant pins on the back of the circuit board, and the process procedure is cumbersome

[0006] 3) The installation process requires high requirements, and it is difficult to guarantee the quality of the outdoor display screen: for in-line LEDs, there must be sufficient process technology to ensure that the LEDs are perpendicular to the PCB board and control each LED to have a consistent height; any deviation will Affects the brightness consistency of the LEDs that have been set, and "mosaic" color blocks with uneven brightness appear

[0007] 4) Large size is not conducive to shortening the pixel pitch of the display screen, thus limiting the improvement of the resolution of the outdoor display screen

[0008] In recent years, the surface-mounted (Surface Mounted Devices, SMD) LED devices that have appeared on the market to replace in-line LEDs - "Top LEDs (Top LEDs)" are moisture-sensitive devices, and the encapsulating colloid and reflective cup plastic The difference in thermal expansion coefficient of the material will easily cause the peeling of the encapsulation gel and the reflective cup, causing moisture from the external environment to enter the device, thereby shortening the life of the Top LED and affecting its working stability

When Top LEDs are applied to outdoor display modules, the potting colloid can only fill the gaps between the Top LEDs, while the upper surface of the plastic reflective cup and the packaging colloid of the Top LED are exposed, so the potting colloid cannot play a role in the LED device. Moistureproof and windproof

Secondly, because it is difficult to control the height of the potting colloid between the top LEDs, it is easy to make the potting colloid pollute the light-emitting surface of the TOP LED, thereby affecting the light output effect of the device

In addition, because Top LED can directly fill the reflective cavity of the device with encapsulant, it cannot provide a specific optical lens structure, and the viewing angle is limited, so it is difficult to meet the wide viewing angle requirements of outdoor display screens.

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