Why Do Prism Sheets Have Bad Conditions？
Feb 15, 2023
BEF, for short, is an optical film with a uniform prismatic pattern precisely formed on the surface of PET, which is very transparent, using acrylic resin. Light-enhancing films are also called prism sheets.
Prism film is a famous light-boosting film that uses a prism-like trigonal lens to refract the light at different angles corresponding to different incident angles to increase the frontal brightness of the screen. Prism film is an optical film made of acrylic resin prism structure on a PET substrate using 3M microreplication technology. Its surface is a micro-prism structure with a height of about 20-50 microns.
According to the principle of geometric optics, the light from the backlight source is circulated through the prism film and the backlight system. Finally, it converges in the frontal direction to achieve the brightening effect.
Prism sheet characteristics
1、The prism sheet widely used in the market is mainly single-sided.
2、Most of the brand materials are wound in a 180-degree pattern, very few will be wound in a 90-degree pattern.
3. Both sides of the material are covered with a protective film. One side is thick and the other side is thin. (Please confirm the prismatic surface and PET surface according to the material property table because of the difference between each brand model)
Note: Because individual brands of materials will do matte treatment on the PET side, it is not recommended to distinguish the colorful side from the PET side by feel.
Prism sheet Usage
Laptop computers, LCD monitors, LCD TVs, portable DVD players, car navigation systems, touch screen cell phones, digital cameras, digital video equipment, etc.
If it is assembled in front of the backlight, the light from the light source will be gathered in the direction of the user of the display device, and the brightness of the front side can be increased by about 100% (in the case of two orthogonal use, there are horizontal and vertical BEF). In addition, the unused light outside the viewing angle is recycled according to the light re-reflection effect and gathered at the most appropriate angle for the user.
The following is a summary of the defective conditions of 3M prism sheet products:
I. Dimple
Acceptable adverse conditions: shallow and not easily detectable swirls (no obvious ring around the swirl).
She rejected undesirable conditions.
1、 The center point is white, the appearance of black, and then a white ring, the outermost black ring (swirl).
2、 The center point is concave, and the other two sides are triangular in the shape of anti-white.
2. Black/Color spot
A diameter greater than or equal to 0.2mm needs to be judged as a defective product.
Causes: foreign body attachment, production conversion caused by.
3. White/Bright spot
When the diameter is greater than or equal to 0.2mm, the product should be judged as defective.
Causes: bad mold, foreign object adhesion, the material itself factory that has.
4. Handling
Fingernail marks or bending, etc.
Causes: handling bad handle caused by.
5. Scratch
Divided into two kinds of scratches parallel or not parallel to the grain of the angles.
Acceptable bad condition: fine or not bright scratch.
Rejected bad condition: coarser or brighter scratch, according to the limits of this judgment.
6. Stain
Opaque or foggy spots (or other unspecified stains).
Causes: protective film or mold caused.
7. Contamination
If the foreign matter is located between the light-enhancing film and the protective film, found when the air blowing gun, or the use of # 467/468 glue stick to remove, can not be used in other ways; if you can not exclude, then according to the two, three standards to determine whether the defective products.
Causes: The processing process or the material itself is caused by adhesion.
8. Damage
Bunch or group of dents.
Reason: Foreign body extrusion or PET hard strip caused.
9. Unevenness
Shadow or long dent, usually located 4-6 inches from the edge.
Causes: often occur in the inner layer of the product end, due to the stress caused by the larger bending.
