JPS5979941A - Crt - Google Patents

Abstract

PURPOSE:To obtain a CRT having no tendency of generating high voltage sparks and riskless of generating a hole on a neck section even if a spot knocking process is applied by depositing a metal oxide film with a specific surface resistance value on an annular area facing the low voltage three-electrode section of an electron gun on the inner periphery of the neck section of a glass bulb. CONSTITUTION:A metal oxide film 12 annularly deposited at the vicinity facing the low voltage three-electrode section of an electron gun on the inner periphery of the neck section 2 of a glass bulb 1 is made from a transition metal of, e.g., Fe, Ni, Zn, Mn, Cr, In, Sn, etc. and has a surface resistance value of 10<2>- 10<13>OMEGA/?. The metal oxide film 12 is formed, for example, by generating an iron nitrate aqueous solution with a predetermined composition, coating with it the predetermined annular area on the inner periphery of the neck section of the glass bulb by a dip method or a spray method, etc., next drying this coating at a temperature of about 150 deg.C for several minutes, then baking it in the air at a temperature of 500-550 deg.C for about 30min.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a cathode ray tube constructed to prevent high voltage sparks from occurring within the neck of the glass bulb.

Conventional configuration and its problems In cathode ray tubes such as color picture tubes, there is a sharp This may produce high voltage sparks with arcing. Although such a spark phenomenon occurs accidentally, it usually occurs when the inner surface of the neck of the glass bulb, especially the inner surface of the neck facing the low-voltage triode,
This occurs due to charging due to electrostatic condensation or leakage current. That is, when the inner surface of the neck portion is positively charged, cold emissions from the low-voltage triode impinge thereon and secondary electron emission occurs, and the emitted secondary electrons are drawn toward the final accelerating electrode. As secondary electron multiplication is repeated in this process, the potential on the inner surface of the neck portion becomes higher and higher, and finally the insulation between the inner surface of the neck portion and the low voltage triode is broken, and the low voltage A spark is generated between the pole part and the inner surface of the neck part, which triggers a high voltage spark between the low voltage triode part and the final accelerating electrode.

In order to prevent the generation of such sparks, conventionally a high resistance coating is attached to the entire inner surface of the neck part of glass pulp, or an arc shield is applied to the electron gun part corresponding to the intermediate part between the low voltage triode part and the final accelerating electrode. For example, an extended electrode called a

However, in the former configuration, approximately 30 to 70
When a high voltage of KV is applied, not only is there a risk of forming a hole in the neck of the glass bulb, but there is also a drawback that the electrical resistance value of the high-resistance film is subject to considerable restrictions. Note that if the electrical resistance value is too large, it will not be possible to satisfactorily achieve the desired purpose, and if it is too small, the high potential at the neck portion on the final accelerating electrode side will be induced to the neck portion on the low voltage triode side. This results in more sparks being generated. It's a trench.
In the latter configuration, even if the protruding electrode were to protrude close to the inner surface of the neck portion of the glass bulb, its effectiveness was limited, and it was not necessarily a complete spark prevention measure.

OBJECTS OF THE INVENTION An object of the present invention is to provide a cathode ray tube that does not generate high-pressure sparks as described above, is easy to manufacture, and does not have the risk of forming holes in the valve neck even when spot non-king treatment is performed. be.

Structure of the Invention In the cathode ray tube of the present invention, the annular region facing the low-voltage triode of the electron gun or the slightly wider annular region of the inner circumferential surface of the neck portion of the glass bulb has a surface resistance value of 102 to 10. A metal oxide coating of 1013 Ω/portion is applied, which will be described in detail below along with examples shown in the drawings.

DESCRIPTION OF THE EMBODIMENTS In the color picture tube shown in the drawings, an integral electron gun 3 enclosed in a neck portion 2 of a glass bulb 1 includes a control electrode 5 and an acceleration electrode 6 supported by a glass support rod 4.
, a focusing electrode 7, a final acceleration electrode 8, and a cathode (not shown). The cathode is insulated and supported within the control electrode 6,
Together with the control electrode 5 and the acceleration electrode 6, it constitutes a low voltage three-pole section. The final accelerating electrode 8 is electrically connected to an internal conductive film 9 made of graphite via a metal tongue 1Q, and the internal conductive film 9 is electrically connected to a button terminal (not shown). The terminals of the electrodes other than the final acceleration electrode 8 are connected to the stem pin 1.
1 to the outside of the tube.

The metal oxide film 12, which was previously provided in a ring shape only in the vicinity of the inner circumferential surface of the neck part 2 facing the low voltage triode part, is made of Fe, Ni, Zn, Mn, Or,
It is made of a transition metal oxide such as In or Sn, and its surface resistance value is 102 to 1015 Ω/1.

Metal oxide film 1211-j: For example, it can be formed as follows.

First, Fe(NOs)s −9H2o −・−=−1
, 2 tons II (%PVA (e%) “””-4,9/l
Ethanol ・・・・・・9.9 Pure
Water: An iron nitrate aqueous solution having a composition of 84.0 // is prepared and applied to a predetermined annular region of the inner peripheral surface of the neck portion of the glass bulb by a dip method or a spray method. This coating was then dried for several minutes at approximately 150'C η1) 11 degrees F.
Calcinate in air at a temperature of 500-550°C for about 30 minutes.

One or more other metal oxides can be used in place of iron nitrate, but in any case, the surface resistance value is determined by the mixing ratio of the metal oxides and the film thickness.

When a practical operation test was conducted by continuously operating the color picture tube thus constructed for 500 hours, no generation of high-pressure sparks as described above was observed. but,
When the surface resistance value of the metal oxide coating 12 exceeds 1013 Ω/hole, there is a tendency to generate sparks, and when the surface resistance value is too small, the film thickness becomes too thick and the adhesive strength becomes insufficient, especially for pipes. There is a risk of falling off during manufacturing. Therefore, the film is formed with a surface resistance value of 10 2 to 10 15 Ω/portion, and a good resistance value of approximately 10 9 to 10 13 Ω/portion.

Of the metal oxide coating 12, the inner peripheral surface of the valve neck part,
It is sufficient to attach it only to the annular region facing the low voltage 3 pole part, but a larger effect can be obtained by attaching it to a slightly wider annular region, and the extended range is limited to the low voltage 3 pole part.
The average distance between the pole part and the inner circumferential surface of the valve neck is the standard. In a cathode ray tube of the type in which a low-voltage electrode is disposed between the focusing electrode and the final accelerating electrode, the expansion is performed or an annular region in which another metal oxide film is directed toward the low-voltage electrode is used. It is desirable to attach it to

Effects of the Invention Since the cathode ray tube of the present invention is constructed as described above, at least 11 annular regions facing the low voltage triode of the electron gun are covered by the metal oxide coating on the inner peripheral surface of the pulp neck portion.
It now shows a resistance value of less than 15Ω/unit, and the positive charge generated by secondary electron radiation is quickly diffused and discharged.
Generation of high voltage sparks due to an increase in the potential of the annular region is prevented. Further, since a capacitor is formed between the metal oxide film and the electron gun electrode, it is possible to prevent potential increase due to even a slight positive charge.

[Brief explanation of the drawing]

The drawing is a partially cutaway side view of a main part of a cathode ray tube embodying the present invention. 1...Glass pulp, 2...Neck part, 3...Electric gun, 6...Control electrode, 6...
...acceleration electrode, 12...metal oxide film.

Claims (1)

[Claims] A metal oxide coating with a surface resistance value of 102 to 1013 Ω/hole is applied to the annular region facing the low voltage triode of the electric r/gun or a slightly wider annular region on the inner circumferential surface of the neck of the glass bulb. A cathode ray tube characterized by having a thin film of.