JPH10269972A - Cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a neck from charge and electric leak on the outer surface of a funnel. SOLUTION: The inner surface of a funnel 1 of a cathode ray tube is coated with interior carbon, and anode voltage is supplied through an anode button 3 from the outside. A neck 4 is positioned in the rear of the funnel 1, and an electron gun for radiating electron beams toward the front is housed. A panel 7 is fixed to the front of the funnel 1, and has a phosphor screen on which electron rays are incident. An exterior carbon 11 for earthing is formed in the region surrounding the whole circumference of the neck 4 along the outer surface of the funnel 1. The exterior carbon 11 is interposed between the anode button 3 and the neck 4 and electrically separates them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube exterior structure. More specifically, the present invention relates to the shape of antistatic exterior carbon coated on the outer surface of the funnel.

[0002]

2. Description of the Related Art FIG. 5 shows a general structure of a cathode ray tube.
As shown, the cathode ray tube is assembled using a funnel 1. The funnel 1 has an interior carbon 2 as an interior conductive film. An anode voltage is supplied to the interior carbon 2 from the outside via the anode pattern 3. A neck 4 is located at the rear of the funnel 1. The neck 4 houses an electron gun 6 that emits an electron beam 5 toward the front. A panel 7 is attached to the front of the funnel 1, and a fluorescent screen 8 on which the electron beam 5 is incident is provided.

When the heater H of the electron gun 6 is heated, thermoelectrons are emitted from the cathode electrode K. The electron gun 6 includes a control electrode (control grid) G1 and controls thermoelectrons. Further, it includes an acceleration electrode (screen grid) G2 and attracts thermoelectrons in the direction of the fluorescent screen 8. The thermoelectrons that have passed through the acceleration electrode G2 are further focused on the focus electrode G3.
, And is accelerated by the anode electrode G4 to irradiate the phosphor screen 8 as the electron beam 5. For this reason, on the fluorescent screen 8, the portion irradiated with the electron beam 5 becomes a spot and shines brightly. In the figure, F1 indicates a prefocus lens, and F1
Reference numeral 2 denotes a focus lens. In the case of a color cathode ray tube, the electron beam 5 is applied to the phosphor screen 8 via a color selection mask 9 such as an aperture grill or a shadow mask.

As shown in FIG. 6, a cathode ray tube for a television or the like performs so-called raster scanning by deflecting an electron beam in a horizontal direction and a vertical direction in order to illuminate the entire screen of a panel 7. A deflector 10 including a horizontal deflection coil and a vertical deflection coil is attached to the neck 4 of the funnel 1 for performing raster scanning,
A deflection current that changes at a high speed is supplied to this. Then, the electron beam in the vacuum is deflected by the influence of the magnetic field. A 15.75 kHz sawtooth horizontal deflection current is supplied to the horizontal deflection coil. At the same time, a vertical deflection current having a sawtooth waveform of 60 Hz is supplied to the vertical deflection coil. As a result, a change in the electromagnetic field occurs, which affects the electron beam and performs horizontal deflection and vertical deflection.

FIG. 7 schematically shows the structure of a color cathode ray tube. The color selection mask 9 is positioned so that the three electron beams 5 respectively excite the red (R), green (G), and blue (B) phosphors 8a applied to the glass surface of the panel. I have. The phosphors 8a of the respective colors have a stripe pattern arranged periodically. For example, a part of the electron beam 5 for exciting the red phosphor may excite the green phosphor without the color selection mask 9 due to the positional relationship between the electron gun 6 and the phosphor screen. That part of the electron beam 5 will be blocked by placing the color selection mask 9 (aperture grill). That is, the color selection mask 9 is placed at a position where only the red phosphor can be seen from the electron beam 5 for red through a slit formed in the mask 9 for color selection.

[0006]

As shown in FIG. 5, an inner surface of a funnel 1 is coated with an interior carbon 2. An anode voltage of, for example, about 27 kV is supplied to the interior carbon 2 via the anode pattern 3.
In addition, the exterior carbon 1 grounded on the outer surface of the funnel 1
Apply 1. The shape is shown in FIGS. 8 (A) and (B). An electric capacitance is formed between the interior carbon 2 and the exterior carbon 11 to serve as a capacitor, and constitute a circuit for smoothing (stabilizing) the anode voltage. However,
The portion where the outer carbon 11 is not applied is charged. In the conventional structure, the exterior carbon 11 is applied so as to partially surround the neck 4. The exterior carbon 11 is not provided between the neck 4 and the anode pattern 3. In this connection, the neck 4 cannot be completely shielded from the charge generated on the outer surface of the funnel 1. The charge of the funnel 1 is transmitted to the outer surface of the neck 4 as time passes, and the inner wall of the neck 4 also becomes charged. As a result, the trajectory of the electron beam generated from the electron gun fluctuates, and misconvergence occurs. In particular, there is a problem in that the side beam of the electron beam is strongly affected by the charging of the inner wall of the neck, and a color shift occurs due to misconvergence. When a cathode ray tube is used for a display of a personal computer or the like, high resolution is required, and color shift due to charging of the inner wall of the neck is a problem to be solved.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems of the prior art, the following measures have been taken. That is, the cathode ray tube according to the present invention includes a funnel, a neck, and a panel as a basic configuration. The funnel has an interior conductive film disposed on an inner surface thereof, and an anode voltage is supplied from the outside. The neck is located at the rear of the funnel and houses an electron gun that emits an electron beam forward. The panel is located in front of the funnel and has a phosphor screen on which electron beams are incident. As a characteristic feature, a grounding conductor is provided in a region surrounding the entire circumference of the neck along the outer surface of the funnel.
The conductor is made of an outer conductive film applied to the outer surface of the funnel or a conductive tape attached to the outer surface of the funnel. Preferably, the conductor is interposed between the anode pattern and an anode mounted on the outer surface of the funnel to supply an anode voltage, and electrically separates the two.

According to the present invention, the outer carbon is applied along the outer surface of the funnel of the cathode ray tube so as to completely surround the entire circumference of the neck accommodating the electron gun. Thereby, it is possible to shield so that the influence of the charging of the outer surface of the funnel by the interior carbon does not reach the neck side. Further, since the outer carbon is interposed between the anode pattern and the neck, leakage from the anode pattern can be completely blocked from the neck side.

[0009]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1A and 1B show a basic configuration of a cathode ray tube according to the present invention, wherein FIG. 1A is a perspective view seen from the rear, and FIG. 1B is a plan view of the rear. For easy understanding, the external shape of the cathode ray tube is simplified to a quadrangular pyramid, and the neck is located at the apex of the quadrangular pyramid. The cathode ray tube includes a funnel 1, a neck 4, and a panel 7 as basic components. Funnel 1
Has an inner conductive film (interior carbon) on its inner surface, and an anode voltage is supplied from the outside through the anode pattern 3. The neck 4 is located at the rear of the funnel 1 and houses an electron gun that emits an electron beam toward the front. The panel 7 is mounted on the front of the funnel 1 and has a phosphor screen on which an electron beam is incident. As a characteristic feature, an exterior conductive film (exterior carbon) 11 for grounding is provided in a region surrounding the entire circumference of the neck 4 along the outer surface of the funnel 1. This exterior conductive film is made of a carbon coating film, and is referred to as exterior carbon 11 in this specification. The exterior carbon 11 is generally prepared by kneading a carbon powder, an organic resin, and water,
This is applied to the outer surface of the funnel 1 by spraying or roller application. The exterior carbon 11 is interposed between the anode pattern 3 and the neck 4 attached to the outer surface of the funnel 1 to supply an anode voltage. The intervening portion 11a electrically separates the anode pattern 3 and the neck 4 from each other. By completely surrounding the neck 4 with the exterior carbon 11, charges charged on the outer surface of the funnel 1 can be shielded from the neck 4. Further, the leak from the anode pattern 3 can be cut off to the neck 4. In this example, the outer conductive film made of the outer carbon 11 is coated on the outer surface of the funnel 1 as a grounding conductor, but a conductive tape such as copper or aluminum is applied to the outer surface of the funnel 1 instead. May be attached. In some cases, the portion 11a of the exterior carbon 11
Only the conductive tape can be replaced.

FIG. 2 shows the anode botan 3 shown in FIG.
It is the fragmentary sectional view which represented the structure of circumference. As shown in the drawing, the interior carbon 2 is coated on the inner surface of the glass wall 1a constituting the funnel. Also, the glass wall 1a
Is coated with an exterior carbon 11. As described above, an anode voltage of about 27 kV is supplied to the interior carbon 2 via the anode pattern 3, while the exterior carbon 11 is grounded. That is, the exterior carbon 11 constitutes a counter electrode of the interior carbon 2 and the glass wall 1.
The charging of the outer surface of a is prevented. The anode pattern 3 fits into a concave portion 1b provided in the glass wall 1a. An anode voltage is externally applied to the anode pattern 3 through the cord 3a. The anode pattern 3 is covered with an insulating cup 3b made of silicon rubber or the like. Silicon grease is applied between the insulating cup 3b and the outer surface of the glass wall 1a to prevent current leakage. Even if the insulation shield made of silicon grease is incomplete or a leak occurs due to the deterioration of the insulation cup 3b, the presence of the exterior carbon 11 does not adversely affect the neck 4 side.

FIG. 3 schematically shows a temporal change of the spot position of the electron beam corresponding to each of the RGB colors.
This spot position corresponds to the irradiation position of the electron beam on the phosphor screen formed on the panel of the cathode ray tube. When the power is turned on, the spot positions of R and B are separated from each other by the distance D ₀ with the spot position of G as the center. If the outer surface of the funnel is charged with the passage of time and the influence is transmitted to the neck, the trajectory of the electron beam fluctuates, and the spot position changes, causing misconvergence and causing color shift. That is, the distance D between the spot positions R ′ and B ′ increases with time.

FIG. 4 is a graph showing the change over time in the spot position. The elapsed time is plotted on the horizontal axis, and the movement amount (D-D ₀ ) of the spot position is plotted on the vertical axis. As is clear from the graph, in the example of the conventional product shown in FIG. 8, the movement amount of the spot position has reached about 100%. In contrast, FIG.
In the invention shown in (1), the movement amount of the spot position falls within about 30%. In this way, the entire circumference of the neck 4 is covered with the exterior carbon 1
By completely enclosing the spot with 1, the amount of movement of the spot position can be reduced to about 1/3 as compared with the related art.

[0013]

As described above, according to the present invention,
By providing the exterior carbon in a region surrounding the entire circumference of the neck along the outer surface of the funnel, the amount of movement of the spot position after turning on the power is reduced, and color shift can be suppressed. Also, the electric leakage from the anode pattern to the neck is shielded, and the risk of damage to the circuit board and the deflector due to the discharge on the outer surface of the cathode ray tube is reduced.

[Brief description of the drawings]

FIG. 1 is a perspective view and a rear view of a cathode ray tube according to the present invention.

FIG. 2 is a partial sectional view of a cathode ray tube according to the present invention.

FIG. 3 is a schematic diagram showing a relative relationship between spot positions of three colors RGB.

FIG. 4 is a graph showing a change over time in a spot position.

FIG. 5 is a schematic sectional view showing a general configuration of a conventional cathode ray tube.

FIG. 6 is a perspective view showing a configuration of a conventional cathode ray tube.

FIG. 7 is a schematic diagram showing a configuration of a conventional cathode ray tube.

FIG. 8 is a perspective view and a rear view showing the exterior structure of a conventional cathode ray tube.

[Explanation of symbols]

1 ... funnel, 2 ... interior carbon, 3 ...
Anode botan, 4 ... neck, 5 ... electron beam,
6 ... electron gun, 7 ... panel, 8 ... phosphor screen, 9
... Mask for color selection, 10 ... Deflector, 11 ...
Exterior carbon

Claims (3)

[Claims] 1. A funnel having an inner conductive film to which an anode voltage is supplied from the outside on its inner surface, a neck located at a rear portion of the funnel and accommodating an electron gun for emitting an electron beam forward, and a neck of the funnel. A cathode ray tube comprising a panel provided with a phosphor screen on which an electron beam is incident at a front portion, wherein a grounding conductor is provided in an area surrounding the entire circumference of the neck along the outer surface of the funnel. A cathode ray tube characterized by the above. 2. The cathode ray tube according to claim 1, wherein the conductor is an exterior conductive film coated on the outer surface of the funnel or a conductive tape attached to the outer surface of the funnel. 3. The method according to claim 1, wherein the conductor is interposed between an anode pattern attached to an outer surface of the funnel and the neck to supply an anode voltage, and electrically separates the two. The cathode ray tube according to claim 1, wherein