JPS5815900B2 - Denshijiyuusouchi - Google Patents

Description

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

It is well known that there are two types of electron guns used in color picture tubes: pi-potential electron guns and uni-potential electron guns.

A pi-potential electron gun has one focusing electrode and one anode electrode arranged on the same axis, and a uni-potential electron gun has one anode electrode added to the pi-potential electron gun. This is the configuration.

These electron guns have problems with the focusing characteristics of color picture tubes, such as blooming of the beam spot or an increase in halo in a high current region, which significantly impairs the focusing characteristics.

For this reason, aberrations have conventionally been avoided by increasing the inner diameter of the electron gun or increasing the electrode length.

Various ideas have been made, such as adjusting the magnification or making the aperture hole smaller.

However, due to limitations on the inner diameter and overall length of the neck of the color picture tube that houses the electron gun, it is difficult to make the electrode tube diameter of the electron gun sufficiently large or to make the electrode length long, and it is difficult to make the aperture hole small. The peak current density at the cathode surface increases.

For this reason, conventional lenses have had the disadvantage that the aberration doubling factor cannot be made sufficiently small, making it difficult to improve focus characteristics.

Therefore, an object of the present invention is to provide an electron gun device that reduces the aberration doubling factor and provides good focusing characteristics.

In order to achieve such an object, the present invention forms a main lens by forming two unipotential lenses, and sets the length of the electrodes forming the unipotential lenses to a predetermined value. This improves focus characteristics, and will be explained in detail below using an actual case.

FIG. 1a shows an electron gun device according to the present invention, in which 1 is a cathode electrode, 2 is a first grid, 3 is a second grid, 4 is a first anode, 5 is a first focusing electrode, and 6 is a The second anode, 7 is a second focusing electrode, and 8 is a third anode, which are arranged on the same axis at a certain distance apart.

The first anode 4, second anode 6, and third anode 8 are commonly connected, and a voltage of about 10 to 25 kV is normally applied to them.

Further, the second focusing electrode 7 and the first focusing electrode 5 are commonly connected and a voltage of about 3 to 9 V is applied thereto.

FIG. 1 shows an electron lens system formed by an electron gun device having such a configuration.

In the figure, Te and Ll are main lenses formed by the first anode 4, the first focusing electrode 5, and the second anode 6, which substantially constitute a unipotential electron gun, and are located near the first focusing electrode 5. It is formed.

R2 is a main lens formed by the second anode 6, the second focusing electrode T, and the third anode 8, which substantially constitute a unipotential electron gun, and is formed near the second focusing electrode T.

Here, if the focal lengths of the main lenses L1 and R2 are fl and f2, respectively, then the apparent focal length f of the large-diameter main lens L3 above is 1/f=1/f, +1/f2-d/ It is given by f1 and f2.

d: Inter-lens distance As is clear from this equation, each main lens L1.
L2 focal length f1. f2 is given as a small value compared to the overall focal length f, and therefore each main lens L
The increase in the spherical aberration of the electron beam caused by 1p''2 can be suppressed as much as possible, and the magnification can be made small.

Furthermore, as described above, the main lens L1. Considering the combination of R2, since the electron beam diverging from one crossover point O is accelerated by the first anode 4, the divergence angle becomes small.

Here, if the amount of spherical aberration is Δr, and the locus position of the electron beam in the electron lens is R2 from the lens axis, and the spherical aberration coefficient is B, then there is a relationship of Δr−BR3, so when the beam divergence angle becomes smaller, the electron beam inside the electron lens becomes smaller. Since the radius R of the beam becomes smaller, spherical aberration can be significantly reduced.

As described above, the present invention reduces the spherical aberration of the electron beam by forming two main lenses, and counters the increase in the halo diameter.
3 by increasing the distance to a certain extent to reduce the magnification and the beam spot diameter.

Next, in such a configuration, the distance between the main lenses L1 and R2 at which the aberration doubling factor is reduced and the beam diameter, .multidot.10-diameter, is in the best condition is determined.

FIG. 2 shows the electron gun device shown in FIG. 1a being driven, and instead of the distance d between the main lens L1 and the main lens R2, the ratio (l/D) of the length l of the second anode 6 to the inner diameter of the electrode is calculated. The characteristics of the beam diameter and halo diameter are shown when various changes are made.

Here, in order to obtain high resolution and sharp images, the beam diameter must be 3.5 mA at a high cathode current of 3 mA.
mm or less, and as long as the halo diameter satisfies the performance of 10.0 mm or less, there is no practical problem.

Therefore, l/D to satisfy this condition is 1.7 to 2.3 from the characteristics shown in FIG. 2 above.

It has been experimentally confirmed that this holds true even when other electrode parameters are changed when the length of an electron gun that can be practically used in a color picture tube is within 200 μ.

As a result, for example, with a neck tube of 36φ, the inner diameter of the electrode is 8.
When the diameter is 9φ, the electrode length of the second anode 6 is 1.51 to 20
．． When used at 5 mm, both the resolution and sharpness are high and a good image can be obtained.

As explained above, according to the electron gun device according to the present invention,
Since the main lens system is constructed by forming two unipotential lenses, and the distance between the two unipotential lenses is set to a predetermined value, the aberration doubling factor can be reduced and the beam diameter, .) low The diameter can be set to a desired state, and therefore an image with high resolution and high sharpness can be obtained.

[Brief explanation of drawings]

FIG. 1a is a simplified configuration diagram showing one embodiment of an electron gun device according to the present invention, FIG. 1 is an explanatory diagram showing a main lens formed by the electron gun device according to the present invention, and FIG. FIG. 3 is a characteristic diagram showing the characteristics of the electron gun device according to the invention. 1... Cathode electrode, 2... First grid, 3... Second grid, 4... First positive electrode, 5...・First focusing electrode, 6...
Second anode, 7... Second focusing electrode, 8...
・Third anode.

Claims (1)

[Claims] 1. A first anode, a second anode, and a third anode arranged along the emission direction of the electron beam, and an anode arranged between the first anode and the second anode and between the second anode and the third anode. In an electron gun device comprising a focusing electrode and two unipotential lenses forming a main lens system, the length of the second anode is set to 1.7 to 2.3 times the inner diameter of the electrode. An electronic gun device characterized by: