JPS63893B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron gun for a color picture tube, particularly an in-line color picture tube.

Generally, the aperture of the main lens of a picture tube electron gun has a large effect on focus characteristics, and in order to obtain good focus characteristics, it is desirable that the aperture be as large as possible. However, in an in-line color picture tube electron gun with three electron beam apertures arranged horizontally in a straight line, the aperture and eccentric distance of the three electron beam apertures must be adjusted to increase the aperture of the three main lenses. If the electron beams are expanded, not only will it be difficult to properly converge the three electron beams to any one point on the phosphor screen surface, but also the main lens forming electrode will be close to the valve neck, resulting in poor high voltage characteristics. The present invention has been made with the above-mentioned points in mind, and the electron gun for color picture tubes of the present invention will be described below along with embodiments shown in the drawings.

In FIG. 1 showing the electrode configuration of a bipotential electron gun embodying the present invention, K ₁ , K ₂ , K ₃ are cathodes, G ₁ is a control electrode, G ₂ is an accelerating electrode, G ₃ is a focusing electrode, and G ₄ indicates the anode. On the mutually opposing plate surfaces of the focusing electrode G ₃ and the anode G ₄ , which are the main lens forming electrodes,
Large diameter beam passage ports g ₃₁ , g ₃₂ , g ₃₃ and g ₄₁ , g ₄₂ , g ₄₃ for passing three electron beams are arranged in-line on a horizontal straight line.
However, the beam passage ports g ₃₁ , g ₃₂ , and g ₃₃ are three independent
Instead of individual circular holes, as shown in FIG. 2, three circular holes overlap and communicate with each other at adjacent ends to form one peanut-shaped hole, that is, a triple circular hole _g3 . Also, beam passage ports g ₄₁ , g ₄₂ , g ₄₃
However, as shown in Figs. 3 and 4, the three circular holes overlap and communicate with each other at their adjacent ends to form one triple circular _hole . has been done.

The flat plate-shaped opposite edges 12, 13 of the partition electrode ₁₁ , which is a U-shaped metal piece mounted inside the focusing electrode G3, serve as partition plates at the two constrictions of the triple circular hole _G3 . Three substantially independent beam passage ports g ₃₁ , g ₃₂ , g ₃₃
is formed. Further, the flat plate-shaped opposite edges 15, 16 of the partition electrode 14, which is a U-shaped metal piece mounted _inside the anode G4, play the role of partition plates at the two constrictions of the triple circular hole _G4 . Therefore, there are three substantially independent beam passage ports g ₄₁ ,
g ₄₂ and g ₄₃ are formed. Note that the x marks in the figure indicate welding points.

Short cylindrical collar portions 17 and 18 protruding inward from the electrodes are formed on the periphery of each of the triple circular holes g ₃ and g ₄ by cutting and raising, respectively, while the two partition electrodes 11, 14, both end edges 12, 13,
Tongue-shaped portions 19, 20, 21, and 22 that fit into the collar portions 17 and 18 are formed on the abdomens of the collars 15 and 16, respectively. In addition, V-shaped recessed portions 23 and 24 are provided at the tip edges of the tongue portions 19 and 20, and
V-shaped recessed portions 25 and 26 are formed at the tip edges of the tongue portions 21 and 22, respectively.

FIG. 5 shows the mutual relationship between the collar portion 18 of the triple circular hole _g4 and the tongue portion 21 of the partition electrode 14. The tongue-shaped portion 21 having the concave notch 25 is a beam passage opening g ₄₁
Although the hole is not a true circular hole, it acts to provide a substantially axially symmetrical electric field to the electron beam passing through it. The reason for this will be explained in more detail with reference to FIG. 4. The central beam passage aperture g ₄₂ should originally have collar portions indicated by virtual arcs AFC and BJE, but the flat end edges of the partition electrode 14
If it is completely partitioned by AKC and BLE, it will no longer be possible to provide an axially symmetrical electric field to the passing electron beam. In addition, the beam passage ports g ₄₁ and g ₄₃ on both sides should originally have collar portions indicated by virtual arcs AHC and BIE, but they are completely partitioned by the flat plate-shaped end portions AKC and BLE of the partition electrode 14, respectively. When put away, each beam passage port
It becomes impossible to provide an axially symmetrical electric field to the electron beam passing through g ₄₁ and g ₄₃ . Therefore, the tongue-shaped part 2 that becomes the partition surface
When V-shaped recessed portions 25 and 26 are formed on the tip edges of the partition surfaces 1 and 22, the electric field distribution due to the tongue portions 21 and 22 becomes weaker in the central region of the partition surface, and spreads from this central region to both sides. Since it gradually becomes stronger as , it is possible to apply a substantially axially symmetrical electric field to the electron beams passing through each beam passage aperture g ₄₁ , g ₄₂ , g ₄₃ .

Note that this also applies to the beam passage ports g ₃₁ , g ₃₂ , and g ₃₃ of the focusing electrode G ₃ . Further, the recessed portions 23, 24, 25, and 26 do not have to be V-shaped, but may be arc-shaped as shown by the broken line in FIG. 5 or a shape similar to this. It is sufficient if the recess is deep in the central region and gradually becomes shallower toward both sides.

Specific numerical examples related to the eccentric distance S, beam passage aperture D, constriction interval G, tongue widths l ₁ and l ₂ and collar height M shown in FIGS. 4 and 5 are shown as embodiments. It is as follows.

S≦D≦1.4S 0.3S≦G≦0.95S 1.5<l ₂ ≦4, l ₁ 0.785l ₂ (S=5.5mm, D=7.0mm, M=1.5mm) V-shape formed on partition electrode Alternatively, the arc-shaped recessed part is not limited to the lower edge of the tongue of the same electrode, but may be the upper edge of the tongue area.
As shown in the figure. Further, as shown in FIGS. 7 and 8, a partition electrode without a tongue-shaped portion may be provided at a distance l ₃ from the hole of the electrode in the tube axis direction. However, it goes without saying that the recessed portion is deep in the central region of the partitioning surface of the hole of the electrode and gradually becomes shallower toward both sides thereof.

In the embodiment shown in FIG. 7, S=5.5mm, D
= 7mm, 0.5mm≦l ₃ ≦2.0mm, l ₁ ′<l ₂ ′,
It can be designed so that 1.0mm<l ₂ ′≦4.5mm.

As described above, the color picture tube electron gun of the present invention has three
In the beam passage aperture, the beam passage aperture is formed by three circular holes and two of the same holes.
and a partition electrode substantially partitioned into three at positions corresponding to the two constrictions, and the partition electrode is provided with recesses that are deep in the central region of each partition surface and gradually become shallower toward both sides. The three main lenses with a large diameter and low distortion can be obtained without increasing the eccentric distance, making it possible to create a color picture tube with excellent focus characteristics, convergence characteristics, and high voltage characteristics at a low cost. It can be provided at low cost.
It goes without saying that the present invention is applicable not only to bipotential electron guns but also to unipotential or other types of electron guns.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view showing the electrode configuration of a bipotential electron gun embodying the present invention, FIGS. 2 and 3 are perspective views of the main parts of the electron gun, and FIG. 4 is a plan view of the main parts. 5 are side sectional views of the same essential parts, and FIGS. 6 to 8 are side sectional views of the essential parts of other embodiments of the present invention. G ₃ ... Focusing electrode, G ₄ ... Anode, g ₃ , g ₄ ... 3
Continuous circular hole, g ₃₁ , g ₃₂ , g ₃₃ , g ₄₁ , g ₄₂ , g ₄₃ ... Beam passing hole, 11, 14 ... Partition electrode, 23, 2
4, 25, 26...Concave cutout.

Claims (1)

[Claims] 1 3 arranged in-line with the main lens forming electrode
The beam passage aperture is formed by a triple circular hole and a partition electrode that substantially partitions the hole into three at positions corresponding to the two constrictions of the hole, and the partition electrode has a respective partition surface. An electron gun for a color picture tube, characterized in that it has a recessed part which is deep in the central region and gradually becomes shallower as it goes to both sides.