JP2744698B2 - Cathode ray tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a cathode ray tube, in particular, an electric field shielding type cathode ray tube having a conductive glass panel or the like on the outer surface of a face plate, and an alternating electric field shielding effect and prevention. The present invention relates to a cathode ray tube having both a glare effect and a low reflection effect.

BACKGROUND ART FIG. 1 is a side view showing a configuration of a general cathode ray tube (CRT). In FIG. 1, the CRT includes a neck portion 6 having a built-in electron gun, a deflection yoke 7, a funnel portion 3, a face plate 4, and a high-pressure button 5. The deflection yoke 7 is connected to a deflection power supply via a lead wire 7a, the electron gun of the neck portion 6 is connected to a drive power supply via a lead wire 6a, and the high voltage button 5 is connected to a high voltage power supply via a lead wire 5a. Each is connected. A fluorescent screen 4b is provided inside a glass panel 4a constituting the face plate 4.

The operation of such a CRT will be described. Neck 6
An electron beam emitted from an electron gun built in the deflecting device is electromagnetically deflected by a deflection yoke 7. The deflected electron beam is accelerated by the high voltage applied to the phosphor screen 4b, and the accelerated electron beam causes the phosphor screen 4b to excite and emit light. Then, this excitation light emission becomes an optical output.

As is clear from the above explanation, the cathode ray tube (CRT)
Has a feature that the voltage applied to the face plate 4 is increased on the principle of operation. That is, a high voltage is applied to the phosphor screen 4b inside the face plate 4 in order to accelerate the electron beam. For example, a conventional cathode ray tube (CRT) has a 20k
High voltage exceeding V has been applied, but recently, with the increase in brightness and resolution of CRTs, CRTs for display monitors have exceeded 25 kV, and CRTs for color TVs have been
In this case, a high voltage of 30 kV or more is applied.

Here, when a high voltage is applied to the fluorescent screen 4b on the inner surface of the face plate 4, the outer surface of the face plate 4 is charged up due to the effect. For CRTs that have not been subjected to antistatic treatment,
When turned off, the outer surface of the faceplate 4 of the CRT is charged up and discharges to a viewer approaching the faceplate 4, causing discomfort to the viewer and sometimes giving an electric shock. . In addition, dust or fine dust in the air adheres to the outer surface of the face plate 4 due to the charge-up of the outer surface of the face plate 4, so that the outer surface of the CRT is contaminated.
This also impairs the image quality of the RT.

Therefore, in order to eliminate the adverse effects of such a discharge phenomenon,
Conducting combing on the outer surface of the face plate 4 or conducting film (coating, glass panel)
By attaching a glass panel 4a having a shape to the outer surface of the face plate 4, charge-up of the outer surface of the face plate 4 is prevented. In such an antistatic treatment type CRT, an electric field shield is formed by these conductive films, and charge collected by the electric field shield is released to the ground to prevent charge-up.

Here, antimony-containing tin oxide has been adopted as the material of the conductive film used in the conventional antistatic treatment type CRT. Specifically, the above-mentioned transparent conductive film was formed by applying a combing material containing antimony-containing tin oxide fine particles as a filler on the glass panel 4a.

Incidentally, a transparent conductive film made of such antimony-containing tin oxide has a resistance of about 10 ⁹ Ω.
Although this resistance value is considerably large as the resistance value of the conductive film, such a resistance value is sufficient for antistatic purposes, that is, for dropping the charge-up to the ground.

However, in recent years, it has been considered that electromagnetic waves have an adverse effect on the human body, and there is a concern that a display monitor such as a CRT may adversely affect the human body due to an alternating electric field mainly emitted from a deflection yoke. In light of this situation, the Swedish National Metrology and Testing Council (MPR-II) and the Swedish Central Labor Council (TCO) in 1991, with a view to preventing the effects of electromagnetic waves emitted from display monitors on the human body, It defines standards for allowable electromagnetic waves leaked from display monitors.

Table 1 shows these standards. As is clear from the table,
According to the Swedish Central Labor Council (TCO) standard, the alternating electric field from 2 kHz to 400 kHz (that is, VLF band) of the electromagnetic wave emitted from the display monitor at a point 30 cm from the CRT faceplate is 1.0 V / m or less. 5Hz to 2kHz (ie, ELF band)
Is specified to be 10 V / m or less.

However, with conventional antistatic treatment type CRTs, especially between 2 kHz and 4
As for the alternating electric field in the 00 kHz VLF band, there is a problem in that it is very difficult to take measures against shielding. Therefore, in the conventional antistatic treatment type CRT, the electromagnetic wave of the alternating electric field in the VLF band of 2 kHz to 400 kHz passes through the face panel of the CRT, affects the viewer, and adversely affects the human body. Had been a problem.

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a CRT (cathode ray tube) for shielding an alternating electric field in a VLF band of 2 kHz to 400 kHz among electromagnetic waves emitted from a display monitor. ). It is another object of the present invention to obtain a CRT that reduces eye strain of the viewer.

In order to achieve the above object, a CRT according to the present invention is characterized in that an alternating electric field in a VLF band of 2 kHz to 400 kHz is shielded by using a transparent conductive film having a small resistance value.

In the CRT according to the present invention, a transparent conductive film is coated on the outer surface of the face panel, and a plurality of terminals, which are connection points with the ground, are provided at ends of the transparent conductive film. Therefore, the potential generated on the outer surface of the face panel is released to the ground via the terminal. In the CRT according to the present invention, the resistance between the terminals is
5 × 10 ³ when the horizontal scanning frequency is 30kHz or more
Ω or lower, and 3 × 10 ³ Ω or lower when the horizontal scanning frequency is 45 kHz or higher.

Note that the transparent conductive film used in the present invention is preferably made of an indium oxide transparent conductive film. The indium oxide transparent conductive film can be formed, for example, by directly applying a paint containing indium oxide fine particles as a filler to the face plate.

Further, the present invention is characterized in that an anti-reflection film is formed on the above-mentioned CRT in order to reduce eye fatigue of the viewer. Therefore, the present invention having an anti-reflection film
In a CRT, a panel or a film on which an antireflection film including at least one indium oxide transparent conductive film layer is formed is provided on the face plate surface.

Note that, in order to reduce fatigue of the eyes of the viewer, an anti-glare treatment may be performed by a spray method after forming an indium oxide film as a first layer.

According to such a cathode ray tube of the present invention, the outer surface of the face plate is reduced in resistance by the conductive indium oxide transparent conductive film. Then, since the outer surface of the face plate provided with the conductivity is connected to the ground by the terminal, the potential generated on the outer surface of the face panel is effectively released to the ground. In this way, by effectively lowering the potential generated on the outer surface of the face panel to ground, the alternating electric field in the VLF band (2 kHz to 400kHz VLF
An electric field shield for shielding the alternating electric field of the band) can be formed.

Further, by adding an anti-reflection film to the transparent conductive indium oxide conductive film or adding a silica film by a spray method, light reflection can be prevented and an anti-glare function can be realized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of a conventional cathode ray tube.

FIG. 2 is a side view of a cathode ray tube according to one embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view in which a cross section of a portion A in FIG. 2 is enlarged.

FIG. 4 is a front view of a cathode ray tube according to one embodiment of the present invention.

FIG. 5 is a graph of alternating electric field (VLF band) and horizontal scanning frequency characteristics measured using a cathode ray tube in which the inter-terminal resistance of the indium oxide transparent conductive film is 3 × 10 ³ Ω and 5 × 10 ³ Ω. It is.

FIG. 6 is a view showing various embodiments of the face plate 14 whose outer surface is covered with a transparent conductive film.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

As shown in FIGS. 2, 3 and 4, in the CRT according to the present embodiment, a conductive film 20 is coated on the outer surface of the face panel 14, and an end of the conductive film 20 is connected to a ground. A terminal 22 is provided. Therefore, the potential generated on the outer surface of the face panel is released to the ground via the terminal 22. CR according to the present embodiment
In T, the resistance value between the terminal 22 is less 5 × 10 ³ Ω If the horizontal scanning frequency used in the above 30 kHz, if the horizontal scanning frequency used in the above 45 kHz 3 × 10 ³ Ω or less.

Hereinafter, the configuration of the CRT according to the present embodiment will be described in detail.

The CRT according to the present embodiment has a neck portion 16 having a built-in electron gun.
, A deflection yoke 17, a funnel section 23, a face plate 14, and a high-pressure button 15. The deflection yoke 17 is connected to a deflection power supply via a lead wire 17a, the electron gun of the neck portion 16 is connected to a drive power supply via a lead wire 16a, and the high-voltage button 15 is connected to a high-voltage power supply via a lead wire 15a. Each is connected.

Here, the glass panel constituting the face plate 14
The surface of 14a is covered with the indium oxide transparent conductive film 20, which is the transparent conductive film according to the present example. In the embodiment, the indium oxide transparent conductive film 20 is applied to a glass shielding panel 26, and the shielding panel 26 is made of an ultraviolet (UV) curable resin 24 having substantially the same refractive index as glass.
Thereby, it is attached to the surface of the glass panel 14a.

Further, a terminal 22 for connecting the indium oxide transparent conductive film 20 to the ground is provided at a peripheral end portion of the transparent conductive film 20. In the embodiment, the terminal 22 is electrically connected to the explosion-proof band 18 by the body foil tape 21. Because this explosion-proof band 18 is dropped to ground,
The potential generated on the outer surface of the glass panel 14a is
2 and the copper foil tape 21 and the explosion-proof band 18 allow the escape.

In the embodiment, the terminals 22 are provided at four locations of the glass panel 11 at 22a, 22b, 22c, and 22d. The copper foil tapes 21 are also provided at four locations 21a, 21b, 21c, and 21d corresponding to the terminals 22. In this embodiment, between terminals 22a and 22b, 22b and 22c
, Between 22c and 22d, between 22b and 22d, between 22a and 22c, and between 22a and 22d, the resistance between them is 5 × when the horizontal scanning frequency is 30 kHz or more. 10 ³ Ω or less, 3 × 10 ³ Ω when used at horizontal scanning frequency of 45 kHz or more
It is as follows.

Next, the operation of the cathode ray tube configured as described above will be described. First, as in the conventional CRT, the electron beam emitted from the electron gun built in the neck portion 16 is electromagnetically deflected by the deflection yoke 17 and the inner surface of the face plate 14 via the high-pressure button 15 as in the conventional CRT. The electron beam is accelerated by applying a high voltage to the fluorescent screen 14b provided in the device, and the energy is used to excite the fluorescent screen 14b to emit light, thereby extracting light output. Also, in the cathode ray tube of the present embodiment, the face plate 14 is also driven by the effect of the high pressure applied to the fluorescent screen 14b on the inner surface of the face plate 14 during driving.
Of the cathode ray tube, an alternating electric field leaks from the face plate 14 of the cathode ray tube.

However, in the cathode ray tube of the present embodiment, a transparent conductive film of indium oxide is formed on the surface of the shielding panel 26, and the transparent conductive film of indium oxide is formed by the terminal 22 provided at the panel end of the shielding panel 26. It is connected to ground via a copper foil tape 21 and an explosion-proof band 18. Therefore,
The charge-up and the alternating electric field generated on the outer surface of the shield panel 26 are shielded and gathered by the electric field shield formed by the indium oxide transparent conductive film, and the terminal 22, the copper foil tape 21, and the indium oxide transparent conductive film are formed. Since it is dropped to the ground via the explosion-proof band 18, the alternating electric field (VLF band) which poses a problem to the human body can be shielded by the outer surface of the face plate.

Generally, among the electromagnetic waves emitted from the display monitor, the alternating electric field (VLF band) of 2 kHz to 400 kHz, which may pass through the face panel of the CRT and adversely affect the human body, is mainly emitted from the deflection yoke. The alternating electric field amount in the VLF band in the antistatic treatment type CRT was a value shown in Table 2 in the measurement result of our experiment.

The alternating electric field (VLF band) in the conventional antistatic treatment type CRT depends on the horizontal scanning frequency, and it has been confirmed that the value of the alternating electric field (VLF band) increases as the horizontal scanning frequency increases. .

On the other hand, in the cathode ray tube according to the present embodiment, the outer surface of the face plate of the CRT is imparted with conductivity by an indium oxide transparent conductive film to reduce the resistance, and the outer surface is dropped to the ground, so that the indium oxide transparent conductive film is formed. An electric field shield can be formed to shield the charge-up and the alternating electric field generated on the outer surface of the shield panel 26. Moreover, the effect is that by setting the resistance between the terminals of the indium oxide transparent conductive film to a predetermined value or less, the leakage of the alternating electric field can be reduced by the Swedish National Metrology and Testing Council (MPR-II) and the Swedish Central Labor Council (MPR-II). TCO) and the like can be suppressed below the standard value specified by international standards, and a sufficient shielding effect can be obtained.

FIG. 5 is a view showing an experimental result measured by using the cathode ray tube of the present embodiment. The resistance between terminals of the indium oxide transparent conductive film of the antistatic treatment type CRT of FIG.
^The graph shows the measured alternating electric field (VLF band) and horizontal scanning frequency characteristics in the case of ³ Ω and 5 × 10 ³ Ω. The measured values were obtained at a position 30 cm away from the face plate 14 of the cathode ray tube.

In FIG. 5, a straight line 100 is a characteristic graph of the alternating electric field (VLF band) versus the horizontal scanning frequency when the inter-terminal resistance value of the indium oxide transparent conductive film is 5 × 10 ³ Ω. As is clear from the figure, when the inter-terminal resistance value of the indium oxide transparent conductive film is set to 5 × 10 ³ Ω or less, the measured alternating electric field (VLF band) around a horizontal scanning frequency of 35 kHz.
Is lower than 1.0 V / m, which indicates that the standards of the Swedish Central Labor Council (TCO) shown in Table 1 can be satisfied.

A straight line 110 shown in FIG. 5 is a characteristic graph of the alternating electric field (VLF band) versus the horizontal scanning frequency when the inter-terminal resistance value of the indium oxide transparent conductive film is 3 × 10 ³ Ω.
As is clear from the figure, even when the cathode ray tube of the present embodiment is used near a horizontal scanning frequency of 50 kHz, if the inter-terminal resistance value of the indium oxide transparent conductive film is 3 × 10 ³ Ω or less, the measured alternation is performed. The electric field (VLF band) is sufficiently 1.0V / m
It can be seen that the above standard is sufficiently satisfied.

From the above, the resistance between terminals of the indium oxide transparent conductive film is set to 5 × 10 ³ Ω or less for use at a horizontal scanning frequency of 30 kHz or more, and indium oxide is used for use at a horizontal scanning frequency of 45 kHz or more. It can be seen that by setting the inter-terminal resistance of the transparent conductive film to 3 × 10 ³ Ω or less, an alternating electric field that may adversely affect the human body can be sufficiently shielded.

Here, various modes can be adopted as a method of covering the outer surface of the face plate 14 with the transparent conductive film.

Second Embodiment By the way, assuming that the outer surface of the face plate 14 is covered with the above-mentioned glass shielding panel 26 as the first embodiment, as a second embodiment, for example, as shown in FIG. Instead of the glass shield panel 26 of the first embodiment, a plastic shield panel 28 can be employed. That is, in the second embodiment, the transparent conductive film 20
Is covered with plastic shielding panel 28,
It is stuck on the glass panel 14a. Shield panel 2
The plastic used for 8 has approximately the same refractive index as glass, and the shielding panel 28 is attached to the glass panel 14a with an ultraviolet (UV) effect resin 24 having approximately the same refractive index as glass. In the cathode ray tube of the second embodiment as well, the transparent conductive film 20 is grounded via the copper foil tape 21 to provide an alternating electric field equivalent to that of the cathode ray tube using the shielding panel 26. A shielding function can be obtained.

Third Embodiment A third embodiment of the present invention is characterized in that a paint containing fine particles of indium oxide as a filler is directly applied to a face plate. As described above, when the paint containing the fine particles of indium oxide as the filler is directly applied to the face plate, the transparent conductive film 30 is directly formed on the glass panel 14a as shown in FIG. 6B. .
Therefore, in the third embodiment, it is not necessary to employ the shielding panels 26 and 28 as in the above-described embodiments.

Also in the cathode ray tube of the third embodiment, the resistance value between the terminals 22 provided at the end of the face of the face plate coated with the paint containing the fine particles of indium oxide as a filler has a horizontal scanning frequency of 30 kHz or more. in the case used is a 5 × 10 ³ Ω or less, the transparent conductive film so as to be ³ × 10 3 Ω or less is formed if the horizontal scanning frequency used in more than 45 kHz. In the cathode ray tube of the third embodiment, the transparent conductive film 30 is grounded via the copper foil tape 21.

In our experiments, even in a cathode ray tube in which a paint containing indium oxide fine particles as a filler was directly applied to the face plate 14, the above-mentioned shielding panel 26 or 28 was used.
An alternating electric field shielding effect equivalent to that of the indium oxide transparent conductive film 20 formed on the surface was obtained.

Fourth Embodiment A fourth embodiment of the present invention relates to a transparent conductive film of indium oxide.
Along with 20, the outer surface of the face plate 14 is covered with an anti-reflection film. A fourth embodiment of the present invention is:
As shown in FIG. 6C, an antireflection film 32 is formed on the transparent conductive film 20. The transparent conductive film 20 is grounded via a copper foil tape 21 connected to a terminal 22 provided at the end. The cathode ray tube of the fourth embodiment has an alternating electric field shielding function as in any of the above embodiments, and a non-reflection function or an anti-glare function of reducing eye fatigue when using a CRT by using an anti-reflection film. have.

A similar effect can be obtained by forming an anti-reflection film 32 on a panel using a plastic shielding panel 28 instead of the glass shielding panel 26 (FIG. 6).
(D)). Similar effects can be obtained by directly applying the transparent conductive film 30 without using the shielding panel as in the third embodiment (FIG. 6E). Further, by adopting the antireflection film 32, the indium oxide transparent conductive film 20 can be formed.
Alternatively, the problem inherent in using 30 can be solved. That is, with respect to the indium oxide transparent conductive film of the above example, if the inter-terminal resistance value is less than 100Ω, the transparent conductive film may be slightly colored or the glossiness of the film may be increased due to its properties. , Fourth
These problems can be alleviated by forming the antireflection film of the embodiment.

In this manner, when a cathode ray tube including at least one indium oxide transparent conductive film layer employs an antireflection film, it is possible to reduce viewer's eye fatigue and to reduce the indium oxide transparent conductive film 20 or 30. Can be solved in the case where is adopted as the transparent conductive film of the present invention. The anti-reflection film is
It may be formed as a part of the panel, or may be made into a film and directly adhered to the surface of the face plate 14.

Fifth Embodiment A cathode ray tube according to a fifth embodiment of the present invention, as shown in FIG.
An SiO ₂ (silica) film 34 is additionally formed by a spray method. The silica film 34 can be formed in any of the cathode ray tubes of the first to fourth embodiments. In the cathode ray tube of the fifth embodiment,
By forming a SiO ₂ (silica) film on the indium oxide transparent conductive film of the shielding panel 26 by a spray method, a cathode ray tube having both the above-mentioned alternating electric field shielding function and anti-glare effect is realized.

Further, as described in the fourth embodiment, when the inter-terminal resistance value of the indium oxide transparent conductive film is less than 100Ω, the transparent conductive film is slightly colored or the glossiness of the film is increased. Also in the fifth embodiment,
It is alleviated by forming the O ₂ (silica) film by the spray method.

[Industrial Applicability] As described above, according to the cathode ray tube of the present invention, the outer surface of the face plate is reduced in resistance by a conductive indium oxide transparent conductive film, and this transparent conductive film is grounded. Since the electric field shield is formed by dropping, an antireflection film is added to the transparent conductive indium oxide conductive film, or a silica film is added by a spray method. In addition to blocking the alternating electric field in the 2kHz to 400kHz VLF band, which may adversely affect the human body by slipping through the face panel of the CRT, the anti-reflection function or anti-glare function to reduce eye fatigue can be realized. is there.

Claims (6)

(57) [Claims] 1. An electric field shielded cathode ray tube comprising: (a) a transparent conductive film covering an outer surface of a face plate of the cathode ray tube; and (b) a plurality of transparent conductive films provided at a peripheral end of the transparent conductive film. (C) the transparent conductive film has a resistance value between each terminal of 5 × 10 ³ Ω when the horizontal scanning frequency is 30 kHz or more; When the horizontal scanning frequency is used at 45 kHz or more, it is 3 × 10 ³ Ω or less. 2. The electric field shielding type cathode ray tube according to claim 1, wherein the transparent conductive film covering the outer surface of the face plate of the cathode ray tube is directly coated with a paint containing fine particles of indium oxide as a filler. A cathode ray tube having an antireflection film including at least one layer formed by the above method. 3. The cathode ray tube according to claim 2, wherein said antireflection film has a layer which is an anti-glare treatment by a spray method as an outermost layer. 4. The cathode ray tube according to claim 2, wherein an anti-glare treatment is performed by a spraying method after the transparent conductive film is formed. 5. An electric field shielding type cathode ray tube comprising: (a) a shielding panel covering an outer surface of a face plate of the cathode ray tube; (b) a transparent conductive film formed on the shielding panel; A) a plurality of terminals provided at a peripheral end of the transparent conductive film, the terminals being provided for connection to the ground; If it is to be used in 30kHz or more, or less 5 × 10 ³ Ω, when the horizontal scanning frequency used in the above 45kHz is less ³ × 10 3 Ω. 6. The cathode ray tube according to claim 5, wherein the transparent conductive film provided on the shielding panel has an antireflection film including at least one indium oxide transparent conductive film layer. Characteristic cathode ray tube.