Test-pattern and final inspection of TV screens
At the final station the finished TV shows geometry, colour-bar and grey-scale patterns in turn. The camera compares each pattern with its reference: corner positions, bar colours and grey steps are measured and the result is entered in the checklist.
Measurement value and pass/fail result of every pattern are kept on the checklist board and in the unit record; a deviating pattern stays marked on the screen and the TV is routed to packing or repair.
- 01 Geometry
- 02 Colour bars
- 03 Grey scale
- 04 Final verdict
The TV is detected by the photo-sensor and stops; on the grid pattern the positions of the corner and centre marks are measured.
- Corner offset
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- Colour diff. ΔE
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- Grey steps
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Scenes are illustrative simulations; they are not customer references or performance guarantees.
Need
On a finished TV the fault sources vary: geometry shift, one colour channel not driven, lost steps in the grey scale. They can be missed in visual comparison; screen brightness and ambient light shift the measurement, and the TV never stops at exactly the same place.
Solution approach
The TV in the portal shows geometry, colour-bar and grey-scale patterns in turn; the camera facing it aligns each pattern to the screen frame and compares it with the reference. The positions of the corner marks, the colour value in each bar's sampling window and the luminance profile of the grey steps are measured; colour and luminance are evaluated relative to the white area of the same frame.
Process steps
- 01
Geometry
The TV is detected by the photo-sensor and stops; on the grid pattern the positions of the corner and centre marks are measured.
- 02
Colour bars
The colour of each bar is measured and compared with its reference value.
- 03
Grey scale
The luminance of the grey steps is measured in order and checked for a steady rise.
- 04
Final verdict
The three results are combined; if one deviates, that pattern stays marked on the screen.
Related applications
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