How is the Shadow Mask Mounted Inside the CRT?
(Portions from: Jeroen H. Stessen (Jeroen.Stessen@philips.com).) The shadow mask is mounted in a diaphragm. The diaphragm is mounted to the inside of the tube with 4 metal springs. In the old days these were bimetal springs. They have an important role for colour purity: they allow the mask to move forward as it expands due to self-heating. Remember: it must dissipate a lot of power and there is no cool air in there… During production the mask is mounted and removed many times to allow for etching of the phosphors. A point light source is precisely positioned at the deflection center of each gun in-turn to expose the photoresist used in laying down the phosphor dots. (I know, you thought they were painted on one spot at a time! 🙂 The mask is never fastened permanently, only clicked in to place just prior to having the envelope glued to the front assembly. As no two masks are identical, each tube is always paired with its own mask. (From: David Moisan (dmoisan@shore.net).) From pict
(Portions from: Jeroen H. Stessen (Jeroen.Stessen@ehv.ce.philips.com)). The shadow mask is mounted in a diaphragm. The diaphragm is mounted to the inside of the tube with 4 metal springs. In the old days these were bimetal springs. They have an important role for colour purity: they allow the mask to move forward as it expands due to self-heating. Remember: it must dissipate a lot of power and there is no cool air in there… During production the mask is mounted and removed many times to allow for etching of the phosphors. A point light source is precisely positioned at the deflection center of each gun in-turn to expose the photoresist used in laying down the phosphor dots. (I know, you thought they were painted on one spot at a time! 🙂 The mask is never fastened permanently, only clicked in to place just prior to having the envelope glued to the front assembly. As no two masks are identical, each tube is always paired with its own mask. (From: David Moisan (dmoisan@shore.net)). Fr
