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US 6,566,800 B2Granted
Method of manufacturing an electron gun
AssigneeKoninklijke Philips Electronics N.V.
InventorRenatus Willem Clemens Van Der Veeken
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AssigneeKoninklijke Philips Electronics N.V.
InventorRenatus Willem Clemens Van Der Veeken
Estimating the term…
A method of manufacturing an electron gun (10) for use in a color display tube (1) is described. The electron gun (10) is provided with an additional electrode (44), positioned between the anode electrode (21a) and the centering cup (23). This additional electrode (44) is part of the beaded unit (29) of the electron gun (10), and this enables very accurate positioning of this additional electrode (44) with regard to its distance to the main focusing section (21) as well as its rotation. This makes it possible to use this additional electrode (44) to improve the quality of the main focusing section (21) by considering it as an integral part of the main focusing section (21). For this reason this additional electrode is referred to as Main lens Field Modifier (MFM) (44). It is shown that by varying the vertical dimension of the apertures (52), (53) of the MFM (44) or the spacing between MFM (44) and main focusing section (21), it is possible to increase the effective lens diameter for spherical aberration, while the effective lens diameter for magnification is kept constant. In other words, the spot performance of the electron gun (10) is improved, while the length of the electron gun (10) is kept unaltered. With a view to obtaining the accuracy needed for a main focusing section (21) with a good tolerance behavior, this new method of manufacturing an electron gun (10) is of great importance.
An electron gun (10) for use in a colour display tube (1), having at least one cathode, a beaded unit (29) comprising, sequentially, viewed in the propagation direction of the electrons, a number of electrodes, having a beam forming section (20) and a main focusing section (21), the main focusing section (21) having a focus electrode (21f) and an anode electrode (21a), the electron gun (10) further comprising a centring cup (23) which is coupled to the anode electrode (22a), characterized in that the main focusing section (21) further comprises an additional electrode (44) positioned in between the anode electrode (21a) and the centring cup (23), which additional electrode (44) is mounted in the beaded unit (29).
A method of manufacturing an electron gun (10) for use in a colour display tube (1), wherein a number of electrodes (20,21) are beaded by securing them to beading rods (27) to form a beaded unit (29) which sequentially comprises, viewed in the propagation direction of the electrons, a beam forming section and a main focusing section (21), the main focusing section (21) having a focus electrode (21f) and an anode electrode (21a), in a further step a centring cup (23) being coupled to the anode electrode (21a), characterized in that the main focusing section (21) further comprises an additional electrode (44) positioned in between the anode electrode (21a) and the centring cup (23), which additional electrode (44 is mounted in the beaded unit (29).
Dependencies are inferred from the claim text.