The quality requirements and standards outlined in the customer-approved LCD display specifications take effect upon customer confirmation. All inspections conducted by the production line's QC, FQC, and QA departments must adhere to the TFT LCD display specifications as the inspection standard.
LCD Display Screen Appearance Inspection Standards
The criteria for QC inspection of appearance (including bright spots, dark spots, scratches, bubbles, light leakage, and murmurs) are formulated by the TFT LCD display manufacturer and reviewed and confirmed by the customer. These criteria generally cover the following areas:
Testing environment and testing tools
1. Under ambient illumination of 600–1200 lux, with auxiliary LED lights and an anti-static fan, conduct the inspection with the LCD screen approximately 18-23 cm away from the examiner's eyes. The inspection directions are 45° to the left, right, and back along the vertical line (using the clock positions of 3 o'clock, 6 o'clock, 9 o'clock, and 12 o'clock).
2. The examiner's visual acuity must reach the standard visual acuity of 1.0 or above.
3. Inspectors must wear static cling wristbands and cots for all eight fingers on both hands.
4. Visual inspection is performed by the visual inspector or by comparing with a film card.
5. Electrical testing uses an electrical testing stand.
6. If the standard does not conform to the specification, the special inspection specifications and engineering changes in the product specification shall prevail.
7. For grayscale detection, please refer to the sample and follow the grayscale inspection standard for detection methods.
8. Electrical testing station: Illumination below 200 LUX; Appearance station: Illumination 600 LUX-1200 LUX; Inspection time: 1-3 seconds.
9. Electrical testing fixture, motherboard, power cord and microcontroller, film comparison card, vernier caliper, magnifying glass, stereo microscope (if necessary), etc.
Inspection content (appearance)
| Project | Judgment criteria |
| Highlight | No bright spots allowed (most clients require 0 bright spots). |
| Dark spot | ≤1 piece (as per customer requirements) |
| dot-shaped foreign objects | Φ ≤ 0.2mm, allowed; 0.2–0.3mm ≤ 1 piece; >0.3mm, NG. |
| Scratch length/width | |
| Width ≤ 0.03mm, Length ≤ 5mm | acceptable |
| Width ≤ 0.05mm, ≤ 2 pieces | acceptable |
| Width > 0.05mm | NG |
| Deep scratches that can be felt with a fingernail | NG |
| Bubbles/Foreign Objects | |
| 大小 | Judgment |
| 0.2mm | Pass |
| 0.2--0.5mm | ≤ 2 is acceptable |
| > 0.5 mm | NG |
| light leak | |
| Visible light leakage at the edges → NG | |
| Slight symmetrical light leakage → Customer-supplied standard | |
| Bright lines in obvious areas on a white background → NG |
See: LCD Display Electrical Performance Inspection Standards
