Patent Grant
7315112
1. Field of the Invention
The present invention relates to a color cathode-ray tube apparatus.
2. Description of Related Art
A color cathode-ray tube apparatus includes a color cathode-ray tube in which an electron gun is housed in an envelope composed of a panel and a funnel connected to each other, and a deflection yoke provided on an outer circumferential surface of the funnel. Three electron beams emitted from the electron gun are deflected in horizontal and vertical directions by the deflection yoke and scan the phosphor screen formed on an inner surface of the panel.
The deflection yoke includes a horizontal deflection coil generating a horizontal deflection magnetic field and a vertical deflection coil generating a vertical deflection magnetic field, and an insulating frame provided between the horizontal deflection coil and the vertical deflection coil. The insulating frame maintains an electrically insulated state between the horizontal deflection coil and the vertical deflection coil, and supports both the deflection coils. On an outer circumferential surface of a substantially cylindrical portion of an end on the electron gun side of the insulating frame, a substantially Ω-shaped metal band is mounted, and both ends of the metal band are fastened with a metal screw, whereby the deflection yoke is fixed to the funnel.
In such a color cathode-ray tube apparatus, in order to enhance an edge of an image to realize high image quality, a velocity modulation coil is used. The velocity modulation coil is composed of a pair of loop-shaped coils attached to positions of the funnel on the electron gun side from the deflection yoke so as to be opposed to each other in a vertical direction. The velocity modulation coil is allowed to generate a magnetic field in the vertical direction to modulate a horizontal scanning velocity of the electron beams, whereby an edge of an image is enhanced (for example, see JP 57(1982)-45650 Y, JP 6(1994)-283113 A).
Furthermore, in a tube axis direction, a convergence and purity unit (CPU) is placed at a position overlapping the velocity modulation coil. The CPU is composed of dipole, quadrupole, and hexapole magnet rings, and a cylindrical holder provided externally on a neck of the funnel and holding these magnet rings. Each of the dipole, quadrupole, and hexapole magnet rings has a configuration in which two annular magnets are stacked. By adjusting the rotation angle around a tube axis of each magnet ring, the static convergence and purity of the electron beams are optimized.
A conductive film is applied to an inner wall surface of the funnel at a place where the deflection yoke is positioned, and is supplied with a high voltage by anode contact. Thus, when a power source of the color cathode-ray tube apparatus is turned ON/OFF, the above-mentioned substantially Ω-shaped metal band and metal screw, which fix the deflection yoke, are charged from the conductive film supplied with the above-mentioned high voltage, with the funnel and the insulating frame of the deflection yoke being dielectrics, and a discharge (spark) may occur toward the velocity modulation coil placed in the vicinity of the metal band and the metal screw. Such a discharge damages an electric circuit that drives the velocity modulation coil.
In order to prevent the occurrence of the discharge, for example, a method for grounding the above-mentioned substantially Ω-shaped metal band that fixes the deflection yoke through a lead to dissipate a charge is considered. However, according to this method, it is necessary to connect a lead, which increases the number of components and man-hours, resulting in an increase in a cost.
Furthermore, enlarging a distance in the tube axis direction between the metal band that fixes the deflection yoke and the velocity modulation coil so as to reduce the possibility of the occurrence of a discharge is considered. However, according to this method, the size of the color cathode-ray tube apparatus in the tube axis direction increases. Furthermore, generally, in terms of the enhancement of an image quality, it is considered to be advantageous that the position in the tube axis direction of an end on the phosphor screen side of the velocity modulation coil is as close as possible to the phosphor screen, and hence, the above-mentioned method contradicts this.
Japanese Utility Model Registration No. 3097458 describes that a removable disk-shaped barrier is provided at a holder of the CPU between the metal band and the velocity modulation coil. Japanese Utility Model Registration No. 3097458 describes the following: this barrier inhibits the formation of a discharge path from the metal band to the velocity modulation coil, so that a discharge can be prevented from occurring. Furthermore, Japanese Utility Model Registration No. 3097458 describes the following: by setting the barrier to be a member separate from the holder of the CPU, the barrier can be formed of a conductive resin with a low insulation resistance or metal; consequently, a discharge can be reduced further.
However, the barrier shown in Japanese Utility Model Registration No. 3097458 cannot prevent the occurrence of a discharge sufficiently. This will be described with reference to
In the above configuration, when a charge amount accumulated in the deflection yoke 130 exceeds a certain value, a discharge path is formed, which extends from the metal band 137 to the velocity modulation coil 150 in the groove 148a, successively passing through an outer circumferential surface of the neck 120, a portion between the neck 120 and an inner circumferential surface of the barrier 170, and a portion between the barrier 170 and the holder 145. Thus, even if the barrier 170 is provided between the metal band 137 and the velocity modulation coil 150, a discharge path with a relatively short creepage distance is formed between the metal band 137 and the velocity modulation coil 150, so that the occurrence of a discharge cannot be prevented completely.
Furthermore, an operation of adjusting the rotation position around the tube axis of the magnet rings 140 of the CPU is performed while an image displayed actually on a screen is being watched. Thus, in the case of placing the barrier 170 for preventing the occurrence of a discharge between the metal band 137 and the velocity modulation coil 150, care should be taken so that the operability of the rotation adjustment of the magnet rings 140 of the CPU placed on an opposite side of the phosphor screen with respect to the barrier 170 is not impaired.
Therefore, with the foregoing in mind, it is an object of the present invention to provide a color cathode-ray tube apparatus capable of preventing a discharge from occurring between a metal band and a metal screw that fix a deflection yoke, and a velocity modulation coil without decreasing the operability of the rotation adjustment of magnet rings of a CPU.
A color cathode-ray tube apparatus of the present invention includes: a cathode-ray tube including a panel in which a phosphor screen is formed on an inner surface, a funnel connected to the panel, and an electron gun housed in a neck of the funnel; a deflection yoke provided on an outer circumferential surface of the funnel, which deflects an electron beam emitted from the electron gun in a horizontal direction and a vertical direction to allow the electron beam to scan the phosphor screen; a CPU including a substantially cylindrical holder provided externally on the funnel, and a plurality of pairs of annular magnet rings provided on an outer circumferential surface of the holder, at a position on the electron gun side from the deflection yoke in a tube axis direction; and a velocity modulation coil held on the holder.
The deflection yoke includes a horizontal deflection coil deflecting the electron beam in the horizontal direction, a vertical deflection coil deflecting the electron beam in the vertical direction, an insulating frame ensuring insulation between the horizontal deflection coil and the vertical deflection coil, a metal band fixing a cylinder portion provided at an end on the holder side of the insulating frame to the funnel, and a metal screw fastening both ends of the metal band.
The holder includes a partition orthogonal to a tube axis at a position on the deflection yoke side from the velocity modulation coil. The partition is formed so as to be integrated with the holder, and the metal screw is placed on a first axis orthogonal to the tube axis.
The partition includes a first partition provided on the first axis so as to hide the metal screw when the deflection yoke is seen from the holder side along the tube axis, and a second partition provided on a second axis orthogonal to the first axis and the tube axis, and assuming that a height from the tube axis of the first partition is H1, a height from the tube axis of the second partition is H2, a minimum height from the tube axis of the partition is Hmin, a height from the tube axis of a pull for performing a rotation operation around the tube axis, of a pair of first magnet rings placed on a side closest to the deflection yoke among the plurality of pairs of magnet rings is HM, and a distance from the tube axis to an outer circumferential edge of a portion of the pair of first magnet rings excluding the pull is RM, relationships: H1>H2, HM−H2>10 mm, Hmin>RM are satisfied.
According to the present invention, a color cathode-ray tube apparatus can be provided, in which a discharge is unlikely to occur between a metal band and a metal screw that fix a deflection yoke, and a velocity modulation coil, without impairing the operability of the rotation adjustment of magnet rings of a CPU.
As shown in
The color cathode-ray tube 10 includes a glass bulb (envelope) composed of a face panel 11 and a funnel 12 connected to each other, a shadow mask 15 attached to an inner side of the face panel 11, and an in-line type electron gun (hereinafter, merely referred to as an “electron gun”) 16 housed in a neck 13 of the funnel 12.
On an inner surface of the face panel 11, a phosphor screen 14 is formed in which respective phosphor dots (or phosphor stripes) of red, green, and blue are arranged periodically. The shadow mask 15 is provided at a substantially constant spacing from the phosphor screen 14. A number of electron beam passage apertures are provided in the shadow mask 15. Three electron beams 18 (three electron beams are arranged in a line parallel to the X-axis, so that only one electron beam on the front side is shown in
The deflection yoke 30 is provided on an outer circumferential surface of the funnel 12. The deflection yoke 30 includes a saddle-type horizontal deflection coil 31 and a toroidal vertical deflection coil 32, and the vertical deflection coil 32 is wound around a ferrite core 33. The three electron beams 18 emitted from the electron gun 16 are deflected in horizontal and vertical directions by a horizontal deflection magnetic field generated by the horizontal deflection coil 31 and a vertical deflection magnetic field generated by the vertical deflection coil 32, and scan the phosphor screen 14 by a raster scan system. An insulating frame 35 is provided between the horizontal deflection coil 31 and the vertical deflection coil 32. The insulating frame 35 maintains an electrically insulated state between the horizontal deflection coil 31 and the vertical deflection coil 32, and supports both the deflection coils 31, 32.
As shown in
As shown in
The partition 46 is formed of an insulating material such as resin so as to be integrated with the holder 45. In the conventional configuration shown in
As shown in
The function of the partition 46 whose height is not constant will be described with reference to
According to the present invention, the partition 46 and the holder 45 are formed integrally, so that a discharge passing through a portion between the partition 46 and the holder 45 does not occur, unlike the conventional configuration shown in
As shown in
Furthermore, as shown in
Furthermore, assuming that a minimum value of the height of the partition 46 is Hmin (Hmin=H2 in the present embodiment), and a distance (radius of an outer circumferential edge) from the Z-axis to an outer circumferential edge of a portion excluding the pulls 41a1, 41b1 of the magnet rings 41a, 41b constituting the first magnet 41 closest to the partition 46 is RM, a relationship: Hmin>RM is satisfied. Thus, by defining the minimum value Hmin of the height of the partition 46, the occurrence of a discharge along a second discharge path 62 (see
In the present invention, it is preferable that the pulls 41a1, 41b1 of the magnet rings 41a, 41b constituting the first magnet 41 closest to the partition 46 overlap the second partition 46b in terms of the position around the Z-axis, as shown in
Furthermore, according to the present invention, it is preferable that a distance in the Z-axis direction between the metal band 37 and the velocity modulation coil 50 is 10 mm or less. Thus, the velocity modulation coil 50 is close to the deflection yoke 30, whereby the velocity modulation sensitivity of the velocity modulation coil 50 is enhanced, and a clearer image with an edge enhanced can be displayed.
Furthermore, it is preferable that a distance in the Z-axis direction between the metal band 37 and the magnet rings 41a, 41b constituting the first magnet 41 is 10 mm or less. Thus, the CPU 40 is close to the deflection yoke 30, whereby the degradation of a focus of an electron beam spot generated by adjusting the rotation of each magnet ring of the CPU 40 can be reduced.
In the above embodiment, as shown in
Furthermore, in the above embodiment, as shown in
In the above embodiment, although the outer circumferential edge of the first partition 46a is set to be an arc with a radius H1, and the outer circumferential edge of the second partition 46b is set to be an arc with a radius H2, the present invention is not limited thereto. For example, the outer circumferential edge of the first partition 46a and/or the second partition 46b may be a curve, a straight line, or a combination thereof other than an arc. In this case, it is assumed that the height of the first partition 46a is defined by the height along a first axis passing through the tube axis and being substantially orthogonal to a longitudinal direction of the metal screw 38, and the height of the second partition 46b is defined by the height along a second axis orthogonal to the tube axis and the first axis.
An example will be described in which the present invention was applied to a color cathode-ray tube apparatus with a diagonal size of 29 inches and a deflection angle of 104°.
As the velocity modulation coil 50, loop-shaped coils 50a, 50b were used, which were obtained by winding a copper wire coated with polyurethane having a wire diameter of 0.4 mm by four turns in a substantially rectangular shape. As shown in
In
As shown in
In
A distance in the Z-axis direction between the metal band 37 and the velocity modulation coil 50 was 4.0 mm. Furthermore, a distance in the Z-axis direction between the metal band 37 and the magnet ring 41a placed on the metal band 37 side of the first magnet 41 was 8.5 mm.
The following two points were evaluated under the condition of variously changing the height H1 of the first partition 46a and a height H2 of the second partition 46b.
1. Occurrence of Discharge:
When a power source of a color cathode-ray tube apparatus was turned ON/OFF, whether or not a discharge occurred between the metal band 37 or the metal screw 38 and the velocity modulation coil 50 was checked. In the case where a discharge occurred, a discharge path thereof further was inspected. As shown in
2. Operability of Rotation Adjustment of Magnet Rings 41a, 41b:
When the rotation positions of the magnet rings 41a, 41b constituting the first magnet 41 closest to the partition 46 were adjusted optimally while a displayed image was being observed, whether or not the partition 46 became an obstacle was evaluated. The case where the partition 46 did not become an obstacle was defined as “Satisfactory”, and the case where the partition 46 became an obstacle was defined as “Unsatisfactory”. After the rotation positions were adjusted optimally, when seen along the Z-axis, the pulls 41a1, 41b1of the magnet rings 41a, 41b overlapped the second partition 46b in terms of the position around the Z-axis.
(Experiment A)
The height H2(=Hmin) of the second partition 46b was changed variously with the height H1 of the first partition 46a being constant (26.5 mm). In Experiment A, a relationship: H1<RB was satisfied. Therefore, when the deflection yoke 30 was seen from the holder 45 side along the Z-axis, a part of the head of the metal screw 38 was exposed outside from the outer circumferential edge of the first partition 46a.
Table 1 summarizes experimental conditions and evaluation results.
In the sample No. A-1, a part of the metal screw 38 was exposed outside from the outer circumferential edge of the first partition 46a, and a relationship: Hmin>RM was not satisfied. In the sample Nos. A-2 to A-7, a part of the metal screw 38 was exposed outside from the outer circumferential edge of the first partition 46a. Thus, a discharge occurred in any of these samples.
Furthermore, in any of the sample Nos. A-1 to A-7, a relationship: HM−H2>10 mm was satisfied, so that the operability of the rotation adjustment of the magnet rings 41a, 41b was satisfactory.
(Experiment B)
The height H2(=Hmin) of the second partition 46b was changed variously with the height H1 of the first partition 46a being constant (27.5 mm). In Experiment B, H1 was equal to RB, so that the head of the metal screw 38 was just hidden by the first partition 46a when the deflection yoke 30 was seen from the holder 45 side along the Z-axis.
Table 2 summarizes experimental conditions and evaluation results.
In the sample No. B-1, a relationship: Hmin>RM was not satisfied, so that a discharge occurred. On the other hand, in the sample Nos. B-2 to B-8, a discharge did not occur.
Furthermore, in the sample Nos. B-1 to B-6 satisfying a relationship: HM−H2>10 mm, the operability of the rotation adjustment of the magnet rings 41a, 41b was satisfactory.
(Experiment C)
The height H2(=Hmin) of the second partition 46b was changed variously with the height H1 of the first partition 46a being constant (28.5 mm). In Experiment C, relationships: H1>RB and WP1>LB were satisfied, so that the metal screw 38 was hidden completely by the first partition 46a when the deflection yoke 30 was seen from the holder 45 side along the Z-axis.
Table 3 summarizes experimental conditions and evaluation results.
In the sample No. C-1, a relationship: Hmin>RM was not satisfied, so that a discharge occurred. On the other hand, in the sample Nos. C-2 to C-9, a discharge did not occur.
Furthermore, in the sample Nos. C-1 to C-6 satisfying a relationship: HM−H2>10 mm, the operability of the rotation adjustment of the magnet rings 41a, 41b was satisfactory.
The applicable field of the present invention is not particularly limited, and the present invention can be used in a wide range such as a TV receiver and a computer display.
The embodiment as described above is illustrated merely for the purpose of clarifying the technical contents of the present invention. The present invention should not be interpreted only based on such a specific example, can be carried out by being varied within the spirit of the invention and scope of the claims, and should be interpreted in a broad sense.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3097458 | Iwasaki | Jul 1963 | A |
| 6404117 | Soneda et al. | Jun 2002 | B1 |
| 7126292 | Morimoto et al. | Oct 2006 | B2 |
| Number | Date | Country |
|---|---|---|
| 57-45650 | Oct 1982 | JP |
| 6-283113 | Oct 1994 | JP |
| 3097458 | Jan 2004 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20060028116 A1 | Feb 2006 | US |
