JPS58209039A - Electron gun frame for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain an electron gun frame that does not require the readjustment of convergence without affecting assembly accuracy by forming the aperture section of a grid electrode opposed to an electrode to which focusing voltage is applied into two stages. CONSTITUTION:The captioned electron gun frame for a CRT consists of three cathodes K arranged in a line that emitting an electron beam and first to fourth grids G1-G4 formed integratedly, respectively. Intermediate voltage and anode voltage are applied to the third electrode G3 and the fourth electrode G4, respectively, and the fourth electrode G4 permits its aperture section to be made eccentric against the third electrode G3. Besides, low voltage is applied to the second electrode G2. The electrode is formed into two stages and permits larger aperture section in the second stage on both sides to the deviated inside, respectively. As a result, the electron gun frame that does not require the readjustment of convergence can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving characteristics of static convergence (hereinafter referred to as STC) shift due to fluctuations in focus voltage in an in-line electron gun in a color cathode ray tube.

Conventionally, as a countermeasure against 8TC deviation with respect to the focus voltage Vf, in addition to the asymmetric electric field formed by the final electrode,
By eccentrically or inclining the openings of the other electrodes, another asymmetric electric field is constructed to compensate for the STC deviation due to Vf fluctuations. Figure 1 (a) g
(b) and (C) are B-UPF as an example of the above.
The structure of the electron gun structure of (pipotential-unipotential focus lens) is shown.

Figure 1(a) shows the main lens of the fifth grid electrode G5 and the sixth grid electrode G6 for taking STC, and the openings on both sides of the bottom of the fifth grid electrode G5 eccentrically outward. A main lens with four grid electrodes G4 forms an asymmetric electric field. Moreover, in FIG. 1(b), the openings on both sides of the bottom of the third grid electrode G3 are eccentrically outwardly,
The brisfocal lens is made asymmetrical with respect to the second grid electrode G2. In addition, FIG. 1(C) shows the fifth grid electrode G.
The openings on both sides of the bottom of the lens are tilted to form two asymmetric lenses.

These electrodes can be applied to all electron guns, but when the opening of the electrode is eccentrically tilted, the amount of intensity and the amount of tilt differ depending on the type of electron gun, so there are many standards, and it is difficult to Also, it greatly affects the precision of the parts and the assembly precision.

In the current in-line electron gun structure, in order to concentrate the three electron beams on the screen, it is necessary to create astigmatism in both side lenses by using a method such as using an eccentric aperture. Of course, other methods than the eccentric aperture may be used as long as they can correctively deflect the electron beams on both sides in a predetermined direction. The amount of deflection of the electron beam by this eccentric aperture is approximately proportional to the amount of eccentricity and the potential difference between the electrodes forming the electron lens, so the potential difference between the electrodes forming the electron lens is accurate and fairly constant. It is not possible to obtain convergence.

In particular, recent color picture tubes undergo final adjustment before being installed in the receiver, and no adjustments are made after they are installed in the receiver. In this case, the potential difference between the electrodes that form the electron lens must be accurate, and if there are fluctuations in the electron gun operating conditions, especially the voltage applied to the focus electrode, when adjusting the picture tube, the STC You will have to readjust and fu.

Therefore, an object of the present invention is to provide an electron gun assembly that does not require convergence readjustment.

An embodiment of the present invention will be explained below with reference to FIG. The electrode structure includes a first grid electrode (1) that is integrally formed with each of three cathodes arranged in a row that emit electron and electron beams.
1. Consisting of a second grid electrode G2, a third grid electrode G3, and a fourth grid electrode G4, a medium voltage is applied to the third grid electrode G3, an anode voltage is applied to the fourth grid electrode G4, and the fourth grid electrode G4 The opening is eccentric with respect to the third grid electrode G3. Also, the second grid electrode G2
A low voltage is applied to the
Each of the large-stage openings has an inwardly eccentric electrode structure. The three electron beams emitted from the three cathodes K are one of the first grid electrode G1 and one of the second grid electrode G2.
The stages advance in parallel, but since the gun shafts of the openings on both sides of the second stage of the second grid electrode G2 are inside of the gun shafts of the first stage, an asymmetric electric field is generated, and the electrons on both sides are The beam is deflected in this part to approach the central electron beam. This amount of deflection is proportional to the voltage of the third grid electrode G3. Next, the electron beams on both sides are connected to the gun axis at the opening of the third grid electrode G3 and to the fourth grid electrode G4 which is eccentric to the outside.
In order to pass through the aperture, the electron beams on both sides are
Get closer to the central beam and concentrate on the screen. This amount of deflection is inversely proportional to the voltage of the third grid electrode G3.

The two lenses mentioned above are greatly affected by the third grid voltage, and when the third grid voltage is high, the G2-03
The amount of beam deflection between G3 and G04 becomes small, although the amount of beam deflection between G3 and G04 becomes large. Conversely, when the third grid voltage is low, the amount of deflection between G2-03 is small (1), and the amount of deflection between G3-04 is large. Therefore, the characteristics of both lenses work to compensate for each other depending on the potential of the third grid electrode, which is most susceptible to voltage fluctuations in the electron gun structure, and the electron beam concentrated on the screen depends on the voltage of the third grid electrode. A constant convergence can be obtained without fluctuations. By making final adjustments to this electron gun assembly as a picture tube, it is possible to make no adjustments after it is installed in a picture receiver.

As described above, according to the present invention, the third grid electrode facing the second grid electrode can be applied to at least all electron guns related to focus, and the eccentricity of the second stage of the second grid electrode can be The temperature is constant in the electron gun, and the assembly accuracy is not affected, and an electron gun that does not require convergence readjustment can be obtained at a low cost.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional electron gun assembly, and FIG. 2 is a sectional view of an embodiment of an electron gun assembly for a color cathode ray tube according to the present invention. K'll 11 +1・Cathode, Gl-... 1st grid electrode, G2・e@fist 2nd grid electrode, G3Φ・
Competition/3rd grid electrode, G4. ...Fourth grid electrode. Figure 1 (a) (b) (C) Figure 2

Claims (1)

[Claims] Between the electrode to which the focus voltage is applied and the electrode to which the anode voltage is applied, astigmatism is produced due to the potential difference between the electrodes that constitute the electron lenses on both sides of the three pairs of lenses facing each other, and the three electron beams are statically focused. 1. An electron gun assembly for a color cathode ray tube, characterized in that the opening of a grid electrode facing an electrode to which a focus voltage is applied is formed in two stages.