Field emission display including a resistor

Details Field emission display including a resistor Field emission display including a resistor

2001-11-29

2002-12-17

Wong, Don (Department: 2821)

Electric lamp and discharge devices: systems

Plural power supplies

Plural cathode and/or anode load device

C313S495000, C313S292000

Reexamination Certificate

active

06495966

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention:
The present invention relates to a resistor having a high area resistance value usable in an image and video display device utilizing an electron source, for example, a cathode-ray tube (hereinafter, referred to as a “CRT”) or a field emission display (hereinafter, referred to as an “FED”), a method for producing such a resistor, a cathode-ray tube including such a resistor, and an FED including such a resistor.
2. Description of the Related Art:
FIG. 6
is a schematic cross-sectional view of a conventional CRT
600
used in a color display apparatus. As shown in
FIG. 6
, the CRT
600
includes a face plate
601
acting as a fluorescent screen and a neck
602
. The neck
602
accommodates a cathode
603
and an electronic lens system
607
. The electronic lens system
607
includes a triode section
604
and a main electronic lens section
605
formed of a plurality of metal cylinders
605
A and
605
B. The electronic lens system
607
is structured so as to project a crossover image of an electronic beam from the cathode section
603
on the face plate
601
using the main electronic lens section
605
. Reference numeral
606
represents a built-in division-type resistor.
In the electronic lens system
607
having such a structure, a diameter DS of a spot image on the face plate
601
is found by expression (1) using an electrooptic magnitude M and a spherical aberration coefficient CS0.
DS=[
(
M×dx+
(½)
M×CS
0×&agr;0
3
)
2
+DSC
2
]
½
  (1),
where dx is a virtual crossover diameter, &agr;0 is a divergence angle of the beam, and DSC is a divergence component of the beam caused by the repulsive effect of a spatial charge.
Recently, efforts have been made to minimize the spherical aberration coefficient CS0 of the main electronic lens section
605
in order to provide a high precision image by minimizing the spot diameter DS on the face plate
601
.
Japanese Laid-Open Publication No. 61-147442, for example, discloses a method for reducing the spherical aberration coefficient CS0 by a built-in division-type resistor. Japanese Laid-Open Publication Nos. 60-208027 and 2-276138, for example, each disclose a method for reducing the spherical aberration coefficient CS0 by forming a convergence electrode of a spiral resistor in the neck of the CRT instead of forming a convergence electrode of the main electronic lens including a plurality of metal cylinders.
The division-type resistor and the spiral resistor are formed in the following manner as described in, for example, Japanese Laid-Open Publication Nos. 61-224402 and 6-275211.
A film is formed of a stable suspension including ruthenium hydroxide (Ru(OH)
3
) and glass particles and excluding an organic binder. The film is formed on an inner surface of a glass tube (formed of, for example, low melting point lead glass having a softening point of 640° C.) by dipping. The film is dried, and then cut into a spiral pattern. Then, the film is baked at a temperature of 400° C. to 600° C. to form a resistor including ruthenium oxide (RuO
2
).
Japanese Laid-Open Publication Nos. 61-147442, 55-14627 and 6-275211 disclose another resistor having a high area resistance value, which is formed of RuO
2
and high melting point glass particles.
The resistor formed of RuO
2
and glass particles is formed in a zigzag pattern on an alumina (e.g., Al
2
O
3
) substrate by screen printing. Such a resistor (referred to as a “glaze resistor”) has a total resistance value of 300 M&OHgr; to 1000 M&OHgr;. The alumina used as the substrate has a thermal expansion coefficient of 75×10
−7
/°C. and a melting point of 2,050° C. Since a CRT requires a resistor which is highly reliable against a high voltage of about 30 kV and an electronic beam, the resistor formed of RuO
2
and glass particles is formed by baking at a relatively high temperature of 750° C. to 850° C.
Japanese Laid-Open Publication No. 7-309282, for example, discloses still another resistor formed of RuO
2
and low melting point glass. The low melting point glass is, for example, PbO—B
2
O
3
—SiO
2
—based glass and includes PbO at 65% or more by weight. The softening point of the low melting point glass is about 600° C. or less.
The above-described spiral or zigzag-pattern resistors are provided in the neck of the CRT in order to minimize the spot diameter on the fluorescent screen and the deflecting power. In addition, a double anode CRT is also developed in which the electronic lens system includes a high resistance layer in a funnel portion thereof.
A resistor used in the electronic lens system of the CRT provides a potential distribution between the anode electrode and a focus electrode, and thus needs to have a sufficiently high area resistance value of 1 G&OHgr;/□ to 100 G&OHgr;/□ (i.e., about 10
9
&OHgr;/□ to about 10
11
&OHgr;/□) in order to prevent a current flow sufficiently to avoid sparking and arc discharge.
Displays utilizing an electron source, such as an FED, also require a high area resistance value provided between an anode and a cathode.
According to the method described in Japanese Laid-Open Publication Nos. 61-224402 and 6-275211, Ru(OH)
3
, which is an insulating substance, is thermally decomposed while being baked at a temperature of 400° C. to 600° C. By such thermal decomposition, RuO
2
, which is a conductive substance, is deposited, and the low melting point glass flows. As a result, fine particles of RuO
2
having a diameter of 0.01 to 0.03 &mgr;m are deposited around the glass particles, which form a resistor.
Such a method has the following problems in obtaining a high resistance value of 5 G&OHgr; to 20 G&OHgr; (area resistance value: 1 M&OHgr;/□ to 4 M&OHgr;/□): (i) the dependency of the area resistance value on the baking temperature increases (i.e., the area resistance value significantly changes when the baking temperature slightly changes); (ii) the temperature coefficient of resistance value (TCR) is increased in a negative direction; and (iii) the load characteristic over a long period of time is inferior. The expression “/□” refers to “per unit area”.
The method described in Japanese Laid-Open Publication Nos. 55-14527, 61-147442 and 6-275211 has a problem in that the resultant resistor cannot be formed on an inner surface of the low melting point glass (having a softening point of 640° C.) used for the CRT due to the high baking temperature of 750° C. to 850° C.
According to the method described in Japanese Laid-Open Publication No. 7-309282, the resistor can be formed on an inner surface of the CRT at a low temperature of 440° C. to 520° C. However, the resistor formed by this method has problems in that (i) the area resistance value significantly changes in accordance with the load characteristic (against application of a voltage of 30 kV at 70° C. at 10
−7
Torr) in the vacuum over a long period of time (5,000 hours); and (ii) the spot diameter on the fluorescent screen is increased due to the load since the TCR is negative.
A tungsten (W)-aluminium oxide-based cermet resistor having a high area resistance value has been developed for use in the electronic tube (see, for example, Japanese Publication for Opposition No. 56-15712). Such a resistor has problems in that (i) a high area resistance value of 10
9
&OHgr;/□ or more is not obtained; and (ii) the TCR is negative and the absolute value thereof is excessively large.
A resistor having an area resistance value of 1 G&OHgr;/□ to 100 G&OHgr;/□ does not need to be shaped into a spiral or zigzag pattern, for use in a CRT. However, the conventional resistive materials have an area resistance value of 1 M&OHgr;/□ to 100 M&OHgr;/□. Since such a range of area resistance values is not sufficiently high, the resistor needs to be shaped into a spiral or zigzag pattern.
Attempts have been made to produce an electronic lens system using a high resistance ceramic cylinder without shaping th

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