How to prevent the LCD screen backlight from turning yellow

      Some customers often report that the white screen turns yellow after the LCD screen has been used for a long time, or the white screen turns yellow after the LCD screen has been stored for a long time. In fact, this yellowing is closely related to the material of the backlight. Today I will briefly analyze how to avoid the backlight color from turning yellow.

      To avoid the problem of yellowing of the backlight material of the TFT LCD screen, it is necessary to start from many aspects such as material characteristics, usage environment, and driving method. In particular, it is necessary to pay attention to the selection and maintenance of the core components of the backlight module (such as LED lamp beads, light guide plates, diffusion films, etc.). The following are specific suggestions:

ONE, The root cause of yellowing of backlight materials

Backlight yellowing is usually related to the aging or poor quality of the following materials:

1. LED lamp bead material: The epoxy resin or silicone encapsulation material of inferior LED lamp beads is easily affected by ultraviolet rays and high temperature and turns yellow.

2. Light guide plate/diffusion film material: Inferior plastics (such as PC or PMMA) have poor weather resistance and are prone to yellowing under long-term light or high temperature.

3. Aging of glue or optical film: If the glue or diffusion film used in the backlight module has poor yellowing resistance, it will accelerate yellowing.

TUO. A guide to avoid pitfalls during the purchase phase

1. Give priority to high-quality backlight materials

· LED lamp beads: Choose full-spectrum LEDs or silicone-encapsulated LEDs (more resistant to yellowing than epoxy resins), and require suppliers to provide anti-UV certification.

· Light guide plate/diffusion film: Choose imported PMMA materials (acrylic) or anti-yellowing PC materials to avoid using cheap recycled plastics.

· Optical film: The diffusion film must be marked with "anti-yellowing" or "UV coating", and the reflective film is preferably silver-plated aluminum film rather than inferior white film.

2. Pay attention to the backlight structure design

· Side-entry vs. direct-down: Side-entry backlight (LED light bar at the edge of the screen) is more likely to cause the light guide plate to age and turn yellow due to local high temperature; direct-down backlight (evenly distributed LED) has better heat dissipation, but the cost is higher.

· Whether it contains anti-aging coating: Some high-end screens will add anti-UV coating on the surface of the light guide plate to delay yellowing.

THREE. Request to provide test report

· Require suppliers to provide weather resistance test report of backlight module (such as high temperature and high humidity test, ultraviolet aging test results).

III. Key measures in use and maintenance

1. Control environmental factors

· Avoid direct ultraviolet rays: Place the screen away from direct sunlight, or use anti-ultraviolet glass/film.

· Control temperature and humidity: The recommended working temperature is 10°C~35°C, and the humidity is 30%~60%. High temperature and high humidity will accelerate the oxidation of materials.

· Reduce heat source interference: Avoid placing the screen close to heating equipment (such as CPU, power adapter) to prevent local high temperature.

2. Optimize driving mode

· Avoid frequent power on and off: Frequent power on will accelerate the aging of LED lamp beads. It is recommended to set a timer power on and off or use energy-saving mode.

· Adjust the brightness appropriately: Too high brightness will accelerate the aging of LED and optical film. It is recommended to adjust dynamically according to the ambient light (such as using the automatic brightness function).

3. Regular maintenance

· Clean and prevent dust: Dust accumulation will lead to poor local heat dissipation. Clean the screen surface and vents regularly with a soft cloth.

· Avoid voltage fluctuations: Use a stabilized power supply or UPS. Unstable voltage may cause the backlight circuit to overload.

IV. Remedial measures after yellowing

If the backlight has slightly yellowed, you can try the following methods:

1. Software adjustment: Adjust the color temperature through the screen color calibration software (reduce the blue channel and improve the white balance), but it cannot solve the physical yellowing.

2. Replace the backlight module: For professional equipment (such as industrial control screens and medical displays), high-quality backlight modules can be replaced (must match the original specifications).

3. Physical covering: Use anti-blue light tempered film to reduce the visual perception of the yellowing area (but it is ineffective for the yellowing itself).