Combination of display tube and deflection unit comprising line deflection coils of the semi-saddle type with a gun-sided extension

• US 5,418,422 A
• Filed: 03/24/1993
• Issued: 05/23/1995
• Est. Priority Date: 05/06/1992
• Status: Expired due to Fees

• Current Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Original Assignee: US Philips Corporation (Koninklijke Philips N.V.)
• Inventors: Penninga, Johannes, Vink, Nicolaas G.
• Primary Examiner(s): BRINICH, STEPHEN M
• Application Number:
  US08/039,612
• Time in Patent Office: 790 Days
• Field of Search: 313/440, 335/210-213, 335/296-299
• US Class Current: 313/440
• CPC Class Codes: H01J 29/762 using saddle coils or printed windings coils per se H01F

Abstract

A display tube has an electromagnetic deflection unit with line deflection coils of the semi-saddle type which are provided at their gun-sided ends with an extension having one single, wedge-shaped window directed towards the gun. Particularly line coma errors and raster errors, which occur in display tubes having display screens of small curvature and/or in the case of extreme long axis: short axis ratios, can be minimized with such line deflection coils.

Claims

1. A display tube comprising an electron gun system, a longitudinal axis, a display screen and an electromagnetic deflection unit, which unit comprises a line deflection coil system having two line deflection coils facing each other, characterized in that each line deflection coil has a gun-sided, lying, lobe and a screen-sided lobe and comprises a first, inner winding sub-assembly and a second, outer winding sub-assembly, each winding sub-assembly comprising two longitudinal conductor groups arranged at both sides of the tube, which groups are connected at their screen side by a connection group crossing in the plane of the screen-sided lobe, the second sub-assembly surrounding the first sub-assembly in such a way that one single, wedge-shaped window with its narrower side at the gun side is formed between the sub-assemblies at the gun side.

2. A display tube as claimed in claim 1, characterized in that, viewed in a plane transverse to the longitudinal tube axis, the longitudinal conductor groups, arranged at both sides of the tube, of the second sub-assembly subtend an angle of less than 120°

with respect to the tube axis proximate to the wider side of the wedge-shaped window.

3. A display tube as claimed in claim 1, characterized in that the display screen has an aspect ratio which is larger than 4:

3, particularly 14;

9 or 16;

9.

4. A display tube as claimed in claim 3, in which the electron beams are produced in a plane parallel to the short axis, characterized in that the line deflection coil system is arranged for deflection along the short axis.