JPS6089037A - Cathode ray tube - Google Patents

Abstract

PURPOSE:To prevent formation of a flaw during assembly so as to avoid formation of the electric field generating source by making the periphery of the aperture which is formed on the surface of the low voltage electrode opposing the high-voltage electrode which in turn constructs the electron lens of the electron gun, depressed compared to other part of the low voltage electrode. CONSTITUTION:The electron lens part of an electron gun consists of a positive electrode 11, the fifth grid 12, the fourth grid 13, and the third grid 14. A high voltage of 25kV is applied between the positive electrode and the fourth grid 13 whereas a voltage of 9kV is applied between the fifth grid 12 and the third grid 14. The edges 34, 35 around the aperture of the fifth grid 12 is depressed by the amount of 50-100mum compared to the central part. Consequently, during assembly process wherein the positive electrode 11 and the grids 12-14 are positioned by inserting a spacer 32 between them and they are fixed by bead glass and finally the spacer 32 is removed, the generation of a flaw on the aperture edge by the spacer 32 can be avoided. Thus the formation of an electric field generating edge is prevented and radiation of the fluorescent surface caused by unrequired electrons is also prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a cathode ray tube with improved voltage resistance characteristics.

[Prior Art] Generally, as shown in FIG. 1, a color cathode ray tube has a glass bulb (4) consisting of a panel part (1), a funnel part (2), and a neck part (3). (4) has an inner conductive film (5) and an outer conductive film (6) on its inner and outer surfaces.
) is provided. The internal conductive film (5) extends to the inner surface of the neck portion (3), and the electron gun assembly (9) is housed in the neck portion (3). As shown in FIG. The first grid and each electrode such as a cathode, a bead glass (16) that holds these electrodes together, a cup-shaped body (19), and a bulb spacer (17) are provided.

The anode (11) and the fourth grid (13) are connected by a connector (21) as shown in FIG. 3, and the anode terminal (8), internal conductive film (5), and valve spacer shown in FIG. (
17), a high voltage is applied from the outside. The fifth lattice (12) and the third lattice (14) are connected by a connector (22), and a height measurement voltage is applied from the outside via a lead wire implanted in a stem (not shown). Similarly, the second lattice (
15) The first grid and cathode are also connected with lead wires using separate connectors! , i, and the respective voltages are applied from the outside. When such a cathode ray tube is operated in a television receiver or the like, taking the case of a multi-step focus electron gun as an example, the anode (11) and the fourth grating (13) are supplied with 25 KV, and the fifth grating (12 )t-3
A voltage of 9 KV is applied to the third grid (14), about 600 KV to the second grid (15), and about -150 V to the first grid number.

The voltage difference applied between the fifth grid (12) and the anode (l l) is 16 KV, but when the television receiver is switched off, the external conductive film (6) of the cathode ray tube and the internal conductive film The charge accumulated in the capacitance between the membrane (5) and the high-voltage power supply is very large, so
To discharge〈〈.

Remains for a long time.

On the other hand, the voltage applied to the fifth grid (12) is quickly discharged to zero potential due to the low impedance of the grid voltage power source. Therefore, the fifth grating (12) and the anode (1
The potential difference with 1) is 25KVk, which is 9 compared to during operation.
KV also increases. Furthermore, since the current flowing through the deflection coil (not shown) also becomes zero, the electrons field-emitted from the points around the apertures of the fifth grid (12), for example, are transferred to the anode (l).
The light passes through the aperture (l) and collides with a fluorescent screen (not shown), emitting light in a narrow area, making it easily noticeable, and causing the problem that the screen glows even when the switch is turned off. Furthermore, if the area around the cathode ray tube is darkened, the current due to field emission will be 0. Even a small current value of lnA causes the screen to emit light, so it has been very difficult to eliminate these problems.

Figure 3 is an enlarged view of the cross section near the high voltage electrode of the electron gun structure (9). Unnecessary electrons are emitted as they are attracted by the electric field perpendicular to , pass through the aperture of the cup-shaped body (19) as shown in orbit (27), and collide with the phosphor screen, causing it to emit light.

Figure 4 is an enlarged view of the vicinity of the field emission source (25) in Figure 3. Since an electric field tilted with respect to the direction is applied, unnecessary electrons are emitted as shown in orbit (27).

On the other hand, a strong electric field parallel to the axial direction of the neck part (3) is applied to the field emission source (28) located at the center of the electrode of the fifth lattice (12), so that all unnecessary electrons are transferred to the anode (11). )
Since the light is attracted by the light and does not reach the phosphor screen, it does not become a problem until the current reaches a large current of several amps. The fifth lattice (
The same electric field as the field emission source (25) is applied to the outside of the field emission source (29) located at the shoulder near the neck (3) of 12). Unwanted electrons are emitted and collide with the inner wall of the neck portion (3), causing secondary electrons (31) to be emitted, some of which reach the phosphor screen and cause it to emit light.

By the way, as shown in Fig. 5, the anode (ll), the fifth grating (12), the fourth grating (13), the third grating (14), etc. are assembled at regular intervals using bead glass (16). When this is done, there is a bead assembly process in which the spacer (32) is inserted, the bead glass (16) is melted and inserted into the bead strap (not shown) of each electrode, and the bead glass (16) is inserted and fixed, and finally the spacer (32) is removed. As is well known, when the spacer (32) is removed, the opposing surfaces of each electrode may be scratched. In order to prevent scratches, the spacer (32) is made of a material such as phosphor bronze which is softer than the electrode material, but it has not been possible to completely eliminate scratches. If this scratch is made near the aperture of the fifth grid (12),
It becomes a field emission source (25) and emits unnecessary electrons, causing the phosphor screen to emit light. Since these unnecessary electrons do not impact the anode (11), adsorbed gas and metal on the anode (11) do not evaporate, and no discharge occurs. Therefore, it was not possible to perform spot knocking in the damaged area, and it was not possible to successfully improve the characteristics.

[Summary of the Invention 1] This invention was made to eliminate the above-mentioned conventional drawbacks, and by making the area around the aperture of the electrode to which a low voltage is applied more secure than other parts, the spacer can be used in the bead assembly process. The purpose is to provide a cathode ray tube that is free from scratches.

[Embodiments of the Invention] Examples of the present invention will be described below with reference to the drawings.

FIG. 6 shows an example of a cathode ray tube according to the present invention, with an anode (
1) and an enlarged view of the vicinity of the fifth lattice (12). Fifth
The periphery of the aperture of the lattice (12) and the shoulder part (35) near the neck part (3) are spaced four times from the center so that they do not come into direct contact with the spacer (32). This recess (
34) and (35) are sufficient if the depth is 50 to 100 p.m, which is about 5 to 10% compared to the electrode spacing, so it can be applied without changing the characteristics of the electron gun much. Such a structure is very effective because even if electropolishing or chemical polishing is applied to the electron gun before assembly, it will not be damaged during the assembly process.

FIG. 7 shows another embodiment, in which the aperture (
If the electrode (33) between electrodes 12a) is narrow and it is difficult to form a four-piece part around the aperture, the four-piece part is made so that it does not come into contact with the spacer (32).

The above description has been about between the anode (11) and the fifth grid (12), but the fifth grid where the high voltage electrode and the low voltage electrode are facing each other is
Similar means can be used between the grating (12) and the fourth grating (13), and between the fourth grating (13) and the third grating (14).

In addition, in the above embodiment, four parts were provided around the aperture and the outer periphery of the low voltage electrode surface, but the light emission of the phosphor screen is mainly due to unnecessary electrons emitted from the field emission source around the aperture. , even if there is no recessed portion (35) on the outer periphery, this does not pose a problem in practice.

[Effect of the Invention 1 As described above, according to the present invention, the area around the aperture on the low voltage electrode surface facing the high voltage electrode is more I than other parts!
! Since the spacer is inserted into the spacer, the assembled poem will not be damaged by the spacer, and the formation of a field emission source can be prevented.
As a result, it is possible to provide a high quality cathode ray tube that does not generate light emission from the phosphor screen due to unnecessary electrons.

[Brief explanation of the drawing]

Figure 1 is a partially broken pressure surface view of a conventional cathode ray tube, Figure 2 is an enlarged sectional view of the neck of the cathode ray tube in Figure 1, and Figure 3 is a high voltage section of the electron gun assembly in a conventional cathode ray tube. 4 is an enlarged view of the main part of FIG. 3, FIG. 5 is an enlarged sectional view of the high voltage part of the electron gun assembly during conventional assembly, and FIGS. 6 and 7 are views of the implementation of the present invention. FIG. 7 is an enlarged view of a main part of a fifth lattice section showing an example. (11)... Anode, (12)... Fifth lattice, (12
a)・Fist/Apacha, (34)...Four members. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Masuo Oiwa

Claims (3)

[Claims] (1) In a cathode ray tube in which an electrode to which a high voltage is applied and an electrode to which a low voltage is applied face each other to form an electron lens, the periphery of the aperture on the surface of the low voltage electrode facing the high voltage electrode. A cathode ray tube characterized by being more advanced than other parts. (2) The cathode ray tube according to claim 1, wherein in addition to the area around the aperture of the low voltage electrode surface, the outer periphery is made larger than other parts. (3) The cathode ray tube according to claim 1 or 2, wherein the recessed portion is 11001 L or less.