JPS6032306B2 - cathode ray tube equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube device, and in particular, an object of the present invention is to prevent discharge inside the cathode ray tube that occurs when switching on and off.

FIG. 1 is a diagram showing the arrangement of accessory parts around a cathode ray tube of a conventional cathode ray tube device, in which an electron gun 3 is sealed in a neck portion 2 of a cathode ray tube 1.

An internal conductive film 4 is applied to the inner wall of the neck portion 2.
an anode button 6 embedded in a part of the funnel part 5;
A high voltage is applied from the high voltage lead wire 7. A crab light body 9 is coated on the inner surface of the panel portion 8 of the cathode ray tube 1, a mask 10 is placed on the inside at a certain interval, and an external conductive film 11 is coated on the outer wall of the funnel portion 5. ing. Further, a deflection yoke 12 is attached to the center of the neck part 2 and the funnel part 5, and is firmly fixed to the neck part by a yoke holder 13 and a vertical fitting 14. There is Purity Magnet 15 on it. The electron gun 3 has an anode 16,
Central electrode 17, second grid 18, first grid 19,
The force sword 20 is held at a certain interval by a key bead glass 21, and the central electrode 17 and the second grid 18
, the first grid 19, the cathode 20', and the lead wire 22, appropriate voltages are applied from the system section 23 and the socket 24, respectively. The anode 16 includes a high voltage lead wire 7 from the shear 25 of the cathode ray tube device, an anode button 6,
A high voltage is applied through the internal conductive film 4 and the spacer 26 .

Further, the deflection yoke 12 and the socket 24 are connected to the shear 25 by a lead wire 27. Figure 2 is an enlarged view of the vicinity of the deflection yoke 12, and the sectional view taken along line A-A' is shown in Figure 3.
As shown in the figure. The clamping fittings 14 of the yoke holder 13 of the deflection yoke 12 are tightened and fixed using screws 28 as shown in FIG. This attachment fitting 14 is charged with a high voltage during operation of the cathode ray tube, so it is set to a ground voltage for safety reasons. Further, the vicinity of the vertical fitting 14 is enlarged and the high voltage development that occurs in this area is explained using a simplified diagram of FIG. 4. If the fastening fitting 14 is directly grounded, the internal conductive film 4 will be The potential at the point P, which is not coated, is the potential between the anode 16 and the point P. Let the capacitance of C,
If the capacitance between the metal fitting 14 and the point P is C2, then the equivalent circuit as shown in Fig. 5 is obtained, and since the dielectric constant of the glass is larger than that in a vacuum, C2 becomes C2. It gets closer. On the other hand, the internal conductive film 4 immediately near the point P,
Since the anode potential is directly applied to the point P, the potential difference between the point P and the inner conductive film end 4A becomes large, and creeping discharge occurs. This potential difference is especially large when the power switch of the cathode ray tube device is turned on, and the creeping discharge occurs every time the switch is turned on. This creeping discharge ionizes the molecules on the surface of the neck glass and emits a blue glow, which sometimes moves to the vicinity of the cathode 20 and the first grid 19, inducing an intraluminal discharge. Alternatively, the blue glow draws out cold emissions from the edge portions of the first grid 19 and the cathode 20, and the two on the glass surface.
Since the secondary electron emission ratio is greater than 1, the potential of the glow emitting portion is gradually positively charged, and discharge within the tube occurs a long time after the power switch is turned on. Or internal conductive film end 4
A creeping discharge occurred in the portion A, and the coating film on the end portion 4A of the internal conductive film was peeled off and scattered, causing leakage current from the millet bundle electrode 17 and the like. Actually, there is a yoke holder 13 between the fastening fitting 14 and the outer wall of the neck part 2, but as shown in Fig. 3, the part of the yoke holder 13 that is glued to the neck part is divided, so that Since they are facing each other with a gap in between, even a slight potential difference will cause an air discharge, so there is no big difference even if you consider that the cotton fitting 14 is in contact with the outer wall of the neck tube 2 as shown in FIG. 4. The reason why creeping discharge tends to occur when the power switch is turned on is because a charging current flows instantaneously and a voltage divided by capacitance is applied, but as time passes after the switch is turned on, leakage current flows and capacitance increases. This is because the direction is to neutralize the voltage generated by the division. In order to prevent such creeping discharge occurring between the end of the internal conductive film and the inner wall of the neck tube, this invention attempts to raise the cotton fitting from the ground and further coat the surface of the fastening fitting with an insulating film. .

First, the technology underlying this invention is shown in FIGS. 6 and 7.

FIG. 6 is a diagram when the annular fastening fitting 14 fitted around the outer periphery of the neck tube (neck portion) 2 is lifted from the ground, and shows the connection between the anode 16 and a point P on the inner wall of the neck tube 2. C, the capacitance between point P and point P2 on the fastening fitting 14, C2, and the capacitance between point P2 and ground, C3.
Fig. 7 shows an equivalent circuit when C2》 since the electric yield rate of glass is larger than the dielectric constant of vacuum or air.
Therefore, the voltage at point P is inversely divided into C and C3. Generally, it is considered that C,>C3, so the voltage at point P is rather close to the anode voltage, and the potential difference between it and the internal conductive film end 4A becomes small.
Creeping discharge becomes less likely to occur. However, if the lead wire or ground wire of the deflection yoke 12 approaches the vicinity of the fastener 14, the above C3 becomes large, and therefore the potential at point P becomes low and between point P and the inner conductive film end 4A. creeping discharge may occur. In order to prevent this problem, it is preferable to apply an insulating coating (film) 30 around the fastening fitting 14 as in the embodiment of the present invention shown in FIG. Point P on the inner wall of the neck tube
, and point P3 on the outer wall is C4, the capacitance between point P3 and point P2 on the fastening fitting 14 is C5, and the capacitance between point P2 and ground is C3. , further internal conductive film 4
The capacitance between C6 and the outer wall of the neck tube facing it is
, the surface resistance of the outer wall of the neck tube is R. The equivalent circuit for such a connection circuit is as shown in FIG. 9, and the potential at point P3 is higher than when the insulating coating 30 is not attached.
Therefore, the potential at point P becomes high, and the internal conductive film end 4A
No creeping discharge occurs between the Also, insulation coating 30
Therefore, the electric charge charged in the fastening fitting 14 is not discharged to the ground potential nearby, and a stable voltage is obtained, so that the creeping discharge does not occur and reliability is further improved. In the above case, if the distance in the direction from the internal conductive film end 4A to the stem portion 23 is taken as the axis and the potential at that point is taken as the vertical axis, the result will be as shown in FIG. In other words, the curve is A if there is no fastener 14, B if the fastener 14 is grounded, C if it is floated from the ground, and D if it is floated from the ground and the insulation coating 30 is attached. Become. The insulating coating 30 may be wrapped around the fastening fitting 14 in the form of a tape, or it may be soaked in a solution of plastic or the like and dried. The above explanation has been about the rare fitting 14 of the deflection yoke 12, but
It goes without saying that this is not limited to this, and the same applies to the tightening fittings for fixing other external parts outside the cathode ray tube to the neck tube 2, such as purity magnets.

Also, although it varies depending on the surface resistance of the outer wall of the neck tube 5, the vicinity of the end of the internal conductive film is within 5 ribs, and there is no possibility that it will affect the potential of the outer wall on the stem 23 side from the end 4A of the internal conductive film. Refers to location. According to the present invention described above, it is possible to prevent discharge within the cathode ray tube that occurs when switching on and off.

Brief explanation of the drawings Figure 1 is a sectional view showing the case where the cathode ray tube accessories are attached, Figure 2 is an enlarged sectional view of the vicinity of the deflection yoke, Figure 3 is a sectional view of Figure 2 A-A', Figure 4 is an enlarged sectional view of the vicinity of the end of the internal conductive film of the neck tube, Figure 5 is an equivalent circuit diagram of capacitance corresponding to Figure 4, and Figure 6 is a configuration diagram showing the technology underlying the present invention. , FIG. 7 is an equivalent circuit diagram of capacitance corresponding to FIG. 6, FIG. 8 is a configuration diagram showing an embodiment of the present invention, FIG. 9 is an equivalent circuit diagram of capacitance in FIG. FIG. 10 is a characteristic diagram showing the potential of the inner wall of the neck tube with respect to the distance from the end of the internal conductive film to the stem side.

In the figure, 2 is a neck tube, 4 is an internal conductive film, 4A is an end of the internal conductive film, 12 is a deflection yoke, 14 is a York fastening fitting, 3
Kawama is an insulating film.

Note that the same reference numerals in the figures indicate the same or equivalent parts. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] 1. An external component such as a deflection yoke is fixed to the neck part by an annular fastening fitting that is fitted into the outer periphery of the neck part of the cathode ray tube and located near the outer wall facing the end of the internal conductive film of this neck part. 1. A cathode ray tube device according to the present invention, characterized in that said fastening fitting is floated from ground potential, and the surface of said fastening fitting is covered with a coating made of an insulating material.