| 1. | Until 1968, every color television sold used the RCA shadow mask concept,
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| 2. | Improvements in conventional shadow masks removed most of its advantages during this period.
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| 3. | As the electron beam hits the shadow mask in these areas it heats unevenly.
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| 4. | Additionally, the lack of the shadow mask makes the penetron much more robust mechanically.
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| 5. | Doming problems due to thermal expansion of the shadow mask was solved in several ways.
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| 6. | While investigating all of these, RCA's teams quickly started focusing on the shadow mask system.
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| 7. | All early color televisions and the majority of CRT computer monitors used shadow mask technology.
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| 8. | This leaves the shadow mask with a small and somewhat randomized field, removing the discoloration.
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| 9. | But it was RCA's success with the shadow mask that dampened most of these efforts.
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| 10. | Development was abandoned when the shadow mask proved successful.
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