5 Easy Ways To Help You Pick A High-Quality Led Display

1). Imperfect manufacturing process

      Uneven mixing lamp

In the production of a large-scale outdoor LED screen project, the number of three primary color lamps is very large. The luminance and chrominance characteristics of the LED lamp depend on the chip used, and the luminance and chrominance characteristics of the chip are related to its batch. In the face of a large number of LED lights, how to ensure that they can be evenly distributed to each module group, directly determines the uniformity of brightness and chroma between the whole screen modules.

Take the threshold setting of light intensity of 20% and wavelength of 2.5nm as an example, it is necessary to identify whether the selected lamps are of different batches and have different bin composition. Even for the same batch of lights and the same bin, the mixed light link cannot be omitted, because the distribution of brightness and chroma in the bin is unknown. For example, although the upper and lower limits of the same wavelength bin of blue light are only 2.5mn different, considering the small blue wide capacity (see Figure 1), if the final display shows a regular distribution, the blue uniformity will be poor. Therefore, it is necessary to develop the corresponding mixed lamp scheme according to the specific situation (the size of the number of lamps, the composition of batches, and bin).

      Fixture for lamp plate passing through the furnace

Because of the specific directionality of the light intensity distribution of the LED lamp, combined with the pattern diagram of the LED, it can be seen that the light intensity will decrease in the direction of deviating from the optical axis. When the LED lamp on the module inclines in the same direction (to a certain extent), such as inclining to the left and right, it will appear the phenomenon of being dimmed or lightened in the large-angle direction; when inclining up and down, it will appear the phenomenon of being dimmed or lightened in the small-angle direction.

Therefore, how to ensure the perpendicularity of the LED lamp after the module passes the furnace should be the guiding ideology of designing the fixture.

—A good set of the fixture to make a good product is inseparable from the use of the process of fixture maintenance, daily regular monitoring, and maintenance fixture confirmation.

2). Special material control: the materials that have a great influence on the display effect mainly include PCB and box.

First of all, as the support of the display part, the flatness of the front side of the box directly determines the splicing accuracy of the module. The flatness between any pixels is ≤ 0.5mm, and the flatness of the box surface is also less than 0.5mm in theory, which does not consider the matching condition of the light plate and the kit. Therefore, it is very important to control the flatness of the front of the box in a reasonable range.

Secondly, the warpage of PCB is also an important factor affecting the accuracy of module splicing. There are many factors affecting the warpage of PCB, such as the material of PCB raw materials, the baking process of PCB manufacturing, the baking process of the lamp plate before passing the furnace, etc. The control of the PCB manufacturing process and post-processing process can effectively control the occurrence of the PCB warpage or deformation, so as to ensure the flatness of the light surface. Combined with the whole product of LED display screen to realize the process characteristics, the control of PCB outline dimension tolerance, positioning hole tolerance, and light hole position tolerance can not be ignored.

3). Module design

–Matching of mask light hole and led gel

In the stage of product design, the verticality of the LED lamp must be maintained to the greatest extent. Therefore, the matching of mask lamp hole and led gel is a problem worthy of careful consideration. Theoretically, the closer the cover lamp hole is to the shape of the LED gel, the better the perpendicularity of the lamp will be. However, first of all, considering that the thermal expansion coefficient of the mask and led gel material is different, with the change of the ambient temperature, under the effect of the law of thermal expansion and contraction, unexpected stress will occur between the mask and led, which may lead to a certain degree of inelastic deformation of the mask and PCB, which is very serious To cause the mask or gel to break. Secondly, the lack of clearance reservations will bring great challenges to PCB processing accuracy, mask injection molding, and the process of LED lamp perpendicularity protection. 

Therefore, the matching relationship between mask hole and led colloid should be considered in terms of matching supply chain process level, thermal expansion coefficient difference, and limiting the inclination of LED in large and small angle direction.

–Mask size control

With the enterprise’s pursuit of product standardization and production efficiency, the module also appears the trend of large size. For example, in the design of a virtual 256 × 256mm module with 16mm point spacing, the use of 256 × 256mm mask is a choice. The large mask will help to reduce the grid effect when the screen is black, but the mask size is large and there are many holes (1024), which brings great difficulties to the injection molding control, characteristic dimension monitoring, deformation, and shrinkage inspection. If 64 × 64mm or 32 × 32mm mask is used, it can reduce the difficulty of monitoring and inspection, reduce the problem of matching stress between the mask and led gel, so as to ensure the display effect.