Electric lamp and discharge devices: systems – Cathode ray tube circuits – Combined cathode ray tube and circuit element structure
Reexamination Certificate
2001-02-16
2002-03-12
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Cathode ray tube circuits
Combined cathode ray tube and circuit element structure
C315S005370, C338S308000, C338S314000, C313S449000
Reexamination Certificate
active
06356021
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a built-in resistor for cathode-ray tube, which is adapted to be employed for a cathode-ray tube such as a color cathode-ray tube, and also related to a cathode-ray tube housing this built-in resistor.
The loading of voltage to a convergence electrode or focus electrode to be employed in an electronic tube such as a color cathode-ray tube for color television receiver has been conducted by dividing an anode voltage by means of a voltage dividing resistor.
FIGS. 1
to
3
illustrate a conventional voltage dividing resistor, wherein
FIG. 1
is a plan view thereof,
FIG. 2
is a cross-sectional view taken along the line II—II of
FIG. 1
, and
FIG. 3
is an enlarged partial view of FIG.
1
.
Referring to
FIGS. 1
to
3
, on one main surface
21
a
of an insulating substrate
21
made mainly of aluminum oxide, there are arranged five terminal electrode layers
22
A to
22
E which are formed by the steps of printing an electrode material comprising metal oxides including ruthenium oxide and lead borosilicate glass, drying and baking the printed layer. A predetermined pattern of a resistance layer
23
is formed so as to interconnect these terminal electrode layers
22
A to
22
E with each other.
This resistance layer
23
is formed by a process wherein a resistance material comprising metal oxides including ruthenium oxide and lead borosilicate glass is printed on the main surface
21
a
in such a pattern that enables to obtain a predetermined resistance value, and the resultant layer is subsequently dried and baked. This resistance layer
23
is subsequently covered with an insulating covering layer
24
a.
In the regions of the insulating substrate
21
where these terminal electrode layers
22
A to
22
E are located, there are formed through-holes
25
penetrating from the main surface
21
a
of the substrate to the other main surface
21
b
of the substrate. These terminal electrode layers
22
A to
22
E are electrically connected with terminals
26
A to
26
E, respectively. One end of each of these terminals
26
A to
26
E is respectively caulked to the corresponding through-hole
25
.
Namely, as shown in
FIG. 3
, one end of each of terminals
26
A to
26
E is constituted by a cylindrical portion
26
a
and a flange portion
26
b
, wherein the cylindrical portion
26
a
is inserted into the through-hole
25
and the distal end portion of the cylindrical portion
26
a
is caulked and fixed to the other main surface
21
b
of the substrate.
By the way, these terminals
26
A to
26
E are generally formed of a non-magnetic alloy such as non-magnetic stainless steel (Fe—Ni—Cr-based alloy) so as not to badly affect the magnetic field to be generated by a deflection yoke (not shown). By the way, this expression of “non-magnetic” means, as far as this technical field is concerned, that the relative permeability of material is not more than 1.01, more preferably not more than 1.005.
The caulked portion
26
c
of the terminal is usually covered with an insulating covering layer
24
b
in order to suppress any abnormal discharge that might be derived from a potential difference between this caulked portion
26
c
and the inner wall of the neck portion of cathode-ray tube (not shown).
This insulating covering layer
24
b
is demanded to have features that it is excellent in heat-resistance so as to withstand against the heating process in the manufacturing process of cathode-ray tube, it is minimal in gas releasability so as not to badly affect the vacuum inside the tube, and it is minimal also in difference in thermal expansion coefficient relative to the insulating substrate. In view of these demands, this insulating covering layer
24
b
is generally formed of a lead borosilicate glass.
However, since the thermal expansion coefficient of these terminals
26
A to
26
E made of a non-magnetic alloy is approximately three times as high as that of the insulating substrate or insulating covering layers, cracks are caused to generate in a region of the insulating covering layer
24
b
which is located in the vicinity of the caulked portion
26
c
of each of the terminals
26
A to
26
E, thereby raising a problem that a piece of the insulating covering layer is peeled away and falls from this caulked portion.
If this caulked portion is exposed in this manner, an abnormal discharge may be more likely to be generated, and furthermore, if this peeled piece of the insulating covering layer is adhered to the electron gun or to the inner wall of the neck portion, the withstand voltage property of these members would be deteriorated. Additionally, if this peeled piece of the insulating covering layer is adhered to the apertures of the shadow mask, the clogging thereof would be resulted, thereby giving rise to the deterioration of the yield of cathode-ray tube.
Whereas, if these terminals are formed by making use of an alloy such as covar (Fe—Ni—Co alloy) or a 42 alloy (42%Fe—Ni alloy), the aforementioned problem of the peeling of the insulating covering layer may be suppressed, since the thermal expansion coefficient of the layer made from these alloys can be made almost identical with the thermal expansion coefficient of the insulating covering layer. However, since these alloys are magnetic alloys exhibiting a high permeability, the magnetic field generated from the deflection yoke would be distorted, thereby raising a problem of generating a defective picture image.
This invention has been made in view of the aforementioned technical problems, and hence, an object of this invention is to provide a resistor for cathode-ray tube which is capable of inhibiting the generation of abnormal discharge at the terminal portion and also capable of inhibiting the peel-off of the insulating covering layer, thereby enabling the cathode-ray tube to display a picture image of high quality.
Another object of this invention is to provide a cathode-ray tube which is provided therein with a resistor which is capable of inhibiting the generation of abnormal discharge at the terminal portion and also capable of inhibiting the peel-off of the insulating covering layer, thereby enabling the cathode-ray tube to display a picture image of excellent quality.
BRIEF SUMMARY OF THE INVENTION
According to this invention, there is provided a built-in resistor for cathode-ray tube which comprises an insulating substrate, a resistance layer formed on one main surface of the insulating substrate, a plurality of terminal electrodes mounted on the resistance layer, and a plurality of terminals connected respectively with the terminal electrodes; wherein the plurality of terminals are individually constituted by a base body comprising a non-magnetic alloy, and by a surface layer which is formed on the surface of the base body and comprising an oxide of the non-magnetic alloy, the plurality of terminals have a relative permeability of not more than 1.005, and the surface layer of each of the plurality of terminals is partially provided with an insulating covering layer.
According to this invention, there is further provided a cathode-ray tube comprising an envelope constituted by a panel portion having a fluorescent screen formed on an inner surface thereof and by a funnel portion having a neck portion; and an electron gun disposed inside the neck portion and comprising a cathode assembly, a plurality of grid electrodes, and a resistor for loading a divided partial voltage on the plurality of grid electrodes; which is featured in that the resistor comprises an insulating substrate, a resistance layer formed on one main surface of the insulating substrate, a plurality of terminal electrodes mounted on the resistance layer, and a plurality of terminals connected respectively with the terminal electrodes; the plurality of terminals being individually constituted by a base body comprising a non-magnetic alloy, and by a surface layer formed on the surface of the base body and comprising an oxide of the non-magnetic alloy; wherein the plurality of terminals have a relative permeabili
Irikura Masao
Iwata Suejiro
Takemoto Aiko
Kabushiki Kaisha Toshiba
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Philogene Haissa
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