What factors can cause LCD screen light leakage?
Date:2025-12-15
What factors can cause LCD screen light leakage?
The main source of light leakage in LCD screens is the uneven escape of light from the backlight module, which is one of the inherent defects of LCD display technology. The following are the main factors that cause light leakage, which are involved in both technical principles and practical applications:
I. Core technical principles and structural factors
1. Working principle of LCD screen: The LCD screen itself does not emit light and requires a backlight module (LED, etc.) to provide a light source. Liquid crystal molecules control the passage of light through deflection, but cannot completely "turn off" all backlighting, especially when displaying black.
2. Differences in panel types:
IPS panel: Due to its wide viewing angle characteristics, the arrangement of liquid crystal molecules makes it easier to see halos from the side in black state, and light leakage is relatively common, especially in the four corners of the screen.
VA panel: high contrast, purer black, and better light leakage control than IPS.
TN panel: Fast response speed, but narrow viewing angle, and the degree of light leakage is usually between the two.
3. Structural design limitations: There are multiple layers of optical films (such as light guide plates, brightness enhancement films, and diffusion films) between the backlight module and the liquid crystal layer. If the flatness, alignment, and gaps of these components are not properly controlled, light will leak out from the gaps.
II. Manufacturing and assembly process factors
This is the main reason for individual differences and severe light leakage.
1. Insufficient assembly accuracy:
The buckle or adhesive between the screen frame (metal or plastic frame) and the panel is not tight, with small gaps.
The positioning of components such as light guide plates and reflective sheets inside the backlight module is inaccurate or there are tolerances.
2. Material quality and quality control:
The quality of the light guide plate is poor, and the light scattering is uneven.
Poor quality, aging, or weak adhesion of sealing materials (such as rubber strips and shading tapes).
The strength of the screen frame is insufficient, which can easily deform and create gaps during assembly or compression.
3. Backlight scheme impact: Direct backlight (light behind the panel) usually has better uniformity and better leakage control than side in backlight (light on the side of the frame), but the body is thicker. Side in backlighting is more prone to light leakage at the edges in order to pursue slimness.
III. Usage and environmental factors
1. Physical compression and deformation:
During transportation or installation, the screen is subjected to improper pressure (such as tightening the installation screws too tightly).
Body design or shell strength issues result in slight deformation after long-term use, compressing the screen structure.
2. Environmental temperature changes: Components (plastic, rubber, metal) have different coefficients of thermal expansion and contraction, which may cause slight deformation or gaps when the temperature changes dramatically.
3. Aging: After long-term use, the sealing material may age and shrink, causing gaps in the originally tight joint.
IV. How to judge and respond?
Mild light leakage: In a pure black background, there is a faint halo at the edge of the screen, especially visible in dark environments. This is quite common in LCD technology, usually within an acceptable range, and does not affect most daily use.
Serious light leakage: Visible spots, beams, or large areas of uneven brightness under normal light, affecting the visual experience of viewing or dark backgrounds. This may be a process defect or quality issue.
Response suggestions:
1. New machine acceptance: Display a pure black image in a dark environment for inspection. If there is serious light leakage, return or exchange the product in a timely manner.
2. Adjust usage habits: Avoid indoor environments that are too dark and adjust screen brightness appropriately to reduce visual discomfort.
3. Avoid external forces: Do not press the screen surface, and apply even force when installing the monitor.
4. Understanding technical limitations: LCD screens with completely no light leakage are extremely rare and require a certain tolerance for mild light leakage. If pursuing ultimate black color and contrast, OLED/Micro LED screens with self luminous technology can be considered.
summary
LCD screen light leakage is the result of the combined effects of structural principles, manufacturing processes, material quality, and usage conditions. Among them, manufacturing assembly accuracy and material quality are the key factors leading to the severity of the problem. For consumers, choosing a brand with excellent quality control during purchase and conducting basic inspections upon receipt is the most effective way to avoid serious light leakage problems.
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