JP2000102027A - Color video receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color video receiver having an excellent magnetic shield effect at a low cost by suppressing the cost of an OMS(outside magnetic shield) for a conventional color video receiver. SOLUTION: On both upper and lower sides of a CRT 110, a pair of plate bodies 162A and 162B and a pair of degaussing coils 150A and 150B for respectively constituting the OMS 160 are attached. The respective plate bodies 162A and 162B are provided with almost rectangular main body parts 164A and 164B for almost covering the degaussing coils 150A and 150B and projected edge parts 166A and 166B projected from the main body parts 164A and 164B to the tube surface direction of the CRT 110. The respective degaussing coils 150A and 150B are arranged in the state of being almost along the peripheral edge part of the respective plate bodies 162A and 162B and wired in the state of being led from the inner side of the main body parts 164A and 164B to the outer side of the projected edge parts 166A and 166B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color video receiver having a cathode ray tube having an internal magnetic shield, a pair of upper and lower demagnetizing coils attached to the cathode ray tube, and an external magnetic shield.

[0002]

2. Description of the Related Art Conventionally, a color cathode ray tube (hereinafter referred to as C) using an aperture grill (AG) or a shadow mask.
In a color television receiver or a color display device equipped with an RT, an electron beam emitted from a cathode under the influence of an external magnetic field such as terrestrial magnetism does not collide with a predetermined phosphor stripe and causes mislanding. In order to prevent color misregistration due to mislanding, an internal magnetic shield (I
MS) and a degaussing coil is arranged outside the CRT. The IMS is formed by assembling a plate made of a ferromagnetic material into a truncated pyramid shape and forming a cylindrical shape through which an electron beam from a cathode passes. Then, by passing an AC decay current through a degaussing coil outside the tube, a magnetic member such as an AG including an IMS in the tube is magnetized, and a demagnetizing field is formed in the tube. As a result, a magnetic field that affects the electron beam Has been made to weaken.

In order to further enhance the effect of reducing the influence of external magnetism, an external magnetic shield (OMS) made of a ferromagnetic material is provided outside the CRT tube, and the magnetic flux generated by the demagnetizing coil is reduced by a magnetic member in the tube. (IMS, AG, etc.), but also a method of flowing to OMS is effective. Various forms of the OMS have been conventionally proposed. For example, Japanese Patent Application Laid-Open No. 2-146890 discloses a housing 10 forming a part of a return path of a degauss coil magnetic flux.
A method is disclosed in which a magnetic circuit made of a ferromagnetic material is attached to the inside to form a magnetic circuit having a low magnetic resistance and obtain a large degauss magnetic flux with a small exciting ampere turn.

Japanese Patent Application Laid-Open No. 8-18989 discloses that
The front part of the chassis (corresponding to the OMS) covers the IMS up to the opening on the electron gun side of the IMS, so that even when a magnetic field such as geomagnetism acts on the cathode ray tube from the outside, the magnetic field component perpendicular to the trajectory of the electron beam increases. In addition, it discloses that mislanding of the electron beam can be prevented, and that the OMS is sufficiently away from the deflection yoke so that it does not affect the magnetic field distribution of the deflection yoke. FIG. 6 is an exploded perspective view showing a configuration example of a color video receiver provided with such a conventional OMS. As shown in the figure, a frame-shaped OMS 20 is provided around the outer periphery of the CRT 10.
A pair of upper and lower degaussing coils 30 are disposed inside the inside 20.

Japanese Patent Laid-Open Publication No. Sho 59-32282 discloses that an OMS is constituted by thin formed steel plates disposed above and below a CRT, and the center of deflection and the equivalent center of the vertical component of terrestrial magnetism are located at substantially the same position. Thus, a method for eliminating mislanding due to the vertical component of terrestrial magnetism is disclosed. FIGS. 7A and 7B are perspective views showing a configuration example of a color video receiver provided with such a conventional OMS.
A pair of plate bodies 40 and 50 constituting the OMS are provided above and below the CRT 10, respectively.

[0006]

However, since the conventional OMS shown in FIG. 6 described above is formed so as to surround the outer periphery of the panel and the funnel of the CRT, the raw materials are required accordingly, and the processing is also required. Because it is difficult to simplify the process (usually by taking out the outer shape from the plate material with a die, press forming, and then combining or welding several pieces to obtain the desired shape), material cost is difficult In addition, both processing costs were high.

On the other hand, the conventional OMS shown in FIG.
Since the OMS-formed plate material may be provided on the upper and lower portions of the device, the cost can be reduced as compared with the method of surrounding the outer periphery. However, in this OMS, since the OMS extends closer to the neck than the deflection center of the CRT, there is a problem that the OMS is close to the deflection yoke and the magnetic field distribution of the deflection yoke is affected. Further, Japanese Patent Application Laid-Open No.
JP-A-32282 does not mention a degaussing coil for magnetizing the OMS, and depending on the form, the magnetic flux generated by the degaussing coil does not flow effectively to the OMS,
There is a risk of impairing the MS shielding effect.

SUMMARY OF THE INVENTION An object of the present invention is to improve the cost of an OMS in a conventional color video receiver, and to provide a color video receiver having a low cost and an excellent magnetic shielding effect.

[0009]

According to the present invention, there is provided a CRT having an IMS made of a ferromagnetic material.
And a pair of upper and lower degaussing coils attached to the outer peripheral portion of the CRT, and an OMS made of a ferromagnetic material attached to the outer peripheral portion of the CRT, wherein the OMS corresponds to the degaussing coil. Each of the plate members has a main body portion having a shape substantially covering the degaussing coil, and a protruding green portion protruding from the main body portion toward the tube surface of the CRT. It is characterized by.

[0010] In the color video receiver of the present invention, the CR
By disposing a degaussing coil and a plate constituting the OMS in the upper and lower portions of T, and passing an AC decay current to the degaussing coil,
The magnetic member such as IMS inside the tube is magnetized, and O outside the tube is magnetized.
The MS is also magnetized to reduce the influence of an external magnetic field. Therefore, the OMS can be configured only by disposing the plate members on the upper and lower portions of the CRT, and the cost of material and processing can be greatly reduced as compared with the conventional OMS surrounding the outer periphery of the CRT.

The OMS plate according to the present invention has a protruding green portion protruding in the direction of the tube surface of the CRT from the main body having a shape substantially covering the degaussing coil, and is therefore arranged without approaching the deflection yoke. This does not affect the magnetic field distribution of the deflection yoke. In the present invention, the OM
Compared to the case without S (only with degaussing coil), a much better magnetic shielding effect can be obtained,
It is possible to obtain magnetic shielding performance that is not much different from that of the conventional OMS.

Further, if the degaussing coil is arranged in a state where it is guided from the inside of the main body of the plate to the outside of the protruding green portion, the degaussing coil approaches the internal magnetic body such as IMS and the degaussing coil. Since the OMS penetrates through the ring of the coil, a constant demagnetizing current allows more magnetic flux to be generated by the IMS.
It can be supplied to a magnetic material such as MS. Further, the loop of the degaussing coil → OMS → IMS → OMS → frame and AG (or shadow mask) allows a magnetic flux to efficiently flow through the magnetic body in the CRT, thereby reducing the amount of geomagnetic drift. Therefore, the electron beam strikes the phosphor more accurately, and the color purity in the color image receiver is improved. Further, by extending the edge on the neck side of the plate to a position covering the opening on the neck side of the IMS, even if a magnetic field such as geomagnetism acts on the CRT from the outside, the trajectory of the electron beam can be reduced. The vertical magnetic field component does not increase, and mislanding of the electron beam can be prevented.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a color video receiver according to the present invention will be described below. FIG. 1 is a top view showing a configuration example of a color video receiver according to the present invention, and FIG. 2 is an exploded perspective view of the color video receiver shown in FIG. FIG. 3 shows the CR of the color video receiver shown in FIG.
FIG. 4 is an abbreviated top view showing the internal structure of T, and FIG. 4 is an abbreviated side sectional view showing the internal structure of the CRT of the color video receiver shown in FIG.

In the color video receiver of this embodiment, the CRT
Reference numeral 110 denotes a face panel 114 fixed to the front opening of the funnel 112 by glass welding.
An annular reinforcing bracket 116 is provided at the welded portion. Further, the holder 116 is provided with four holders 118 corresponding to the four corners of the CRT. A neck 120 provided with an electron gun (not shown) is integrally provided at the rear end of the funnel 112.
An anode terminal 122 is provided on the upper surface of the funnel unit 112.

On the inside of the face panel 114,
An AG (or shadow mask) 124 is arranged to face the phosphor screen 114A. The AG 124 is a color selection electrode plate having a number of slits corresponding to the phosphor pattern. Each of the pair of the vertical frame and the horizontal frame forms a substantially rectangular frame 124A, which is fixed to the frame by welding. I have. An IMS 126 is disposed behind the AG 124. This IMS1
Numeral 26 is a plate made of a ferromagnetic material assembled into a truncated pyramid shape and formed into a cylindrical shape that is expanded toward the face panel 114, and allows an electron beam emitted from an electron gun to irradiate the fluorescent screen.

On the upper and lower sides of the CRT 110, a pair of plate members 162A and 16
2B and a pair of degaussing coils 150A and 150B are attached. That is, the OMS 160 of the present example has the plate members 162A and 162B made of a ferromagnetic material arranged on the upper and lower sides of the CRT 110. Each plate 162A, 162
B is a substantially rectangular main body 164A, 164B that substantially covers the degaussing coils 150A, 150B;
A, 166B, and projecting green parts 166A, 166B protruding from the tube surface (front) of the CRT 10 from the front side. Each protruding green portion 166A, 166B is connected to each main body portion 164A, 164.
B has a width slightly smaller than that of the face panel 11.
4 are arranged facing both upper and lower sides.

Each of the degaussing coils 150A, 150B
Are arranged substantially along the periphery of each of the plate bodies 162A and 162B. As shown in FIG. 4, the green parts 166A and 166A protruding from the inside of the main bodies 164A and 164B.
It is wired so as to be guided to the outside of 6B. Therefore, each plate 162A, 162B is connected to each degaussing coil 150
A and 150B are arranged so as to penetrate the loop. The main body 164A of the plate body 162A on the upper surface side
Has a cutout 168 at the edge on the neck side so as to avoid the anode terminal 122. Also, the degaussing coil 150A on the upper surface side is mounted in a loop that avoids the anode terminal 122. In addition, each degaussing coil 150A, 1
The loops on the neck side of 50B are plate bodies 162A, 162
It is arranged in a state that it slightly protrudes from the edge of B.

The plate members 162A and 162B can be fixed by various methods such as a method of fixing the plate members 162A and 162B by fitting them between the holders 118 and a method of fixing the plate members 162A and 162B to the holder 118 by other fasteners (brackets, bolts, etc.). It can be adopted. Each of the degaussing coils 150A and 150B is provided on the plate 162A and 162B side, for example.
A structure (a locking claw or the like) for holding 50B is provided, and the plates 162A, 162B are mounted on the CRT 110 with the degaussing coils 150A, 150B mounted on the plates 162A, 162B in advance.
To the demagnetizing coils 150A, 150B
Can be fixed to the CRT 110.

In the color video receiver of the present embodiment as described above, the plate 162A is provided above and below the CRT 110.
The OMS 160 can be configured only by installing the 162B, and the material cost and the processing cost can be significantly reduced as compared with the conventional OMS that surrounds the outer periphery of the CRT 110. Further, the plate 16 of the OMS 160 in the present invention is used.
2A and 162B are provided on the CRT 11 from the main bodies 164A and 164B having a shape substantially covering the degaussing coils 150A and 150B.
The protruding green portions 166A and 166B protruding in the direction of the tube surface 0
, It is arranged without approaching a deflection yoke (not shown), and does not affect the magnetic field distribution of the deflection yoke.

In this embodiment, a much superior magnetic shielding effect can be obtained as compared with the case where the OMS 160 is not provided (only the demagnetizing coil), and the conventional OMS 160 is used.
It is possible to obtain a magnetic shielding performance that is not much different from that of the magnetic shield 160. The degaussing coils 150A, 1
50B, the main body 164 of the plate bodies 162A, 162B.
A and 164B, the magnets 166A and 166B are guided outside the protruding green portions 166A and 166B.
A and 150B are close to the internal magnetic body such as IMS, and the OMS in the ring of the degaussing coils 150A and 150B.
160 passes through, so with a constant demagnetizing current,
More magnetic flux can be supplied to a magnetic body such as the IMS 126.

Further, as shown in FIG.
The loop of 0A → OMS plate 162A → IMS 126 → OMS plate 162B → Frame 124A and AG 124 allows a magnetic flux to flow efficiently through the magnetic material in the CRT 110, thereby reducing the amount of geomagnetic drift.
Therefore, the electron beam strikes the phosphor more accurately, and the color purity in the color image receiver is improved. Further, by extending the edge of the plate body 162A, 162B on the neck side to a position covering the opening of the IMS 126 on the neck side, even if a magnetic field such as geomagnetism acts on the CRT 110 from the outside, the electron beam The magnetic field component perpendicular to the trajectory does not increase, and mislanding of the electron beam can be prevented.

FIG. 5 is an explanatory diagram showing measured values of the magnetic east density and the amount of geomagnetic drift in the color video receiver of the present embodiment in comparison with a conventional color video receiver. FIG. 5 (A)
When an AC decay current is applied to the degaussing coils 150A and 150B, the IMS 126 and the frame 124 in the CRT 110
This is a measurement of the magnetic east density flowing in A, and is a comparison of the measured value of the present example with the measured value without the OMS and the measured value of the conventional example shown in FIG. Here, the magnetic flux density was measured by a method in which a search coil was wound around the IMS 126 and the frame 124A, and the output voltage was measured with an oscilloscope via an integrator. The numerical values in the figure are relative values for each magnetic member when the measured value of the conventional example shown in FIG. 6 is set to 1.0. As shown in FIG. 5A, the OMS 160 of the present example and the conventional OMS shown in FIG.
It can be seen that the magnetic flux density flowing through the frame 124A is substantially equal. In addition, comparing the OMS 160 of the present example with the case without the OMS, the present example shows that the frame 124A
It can be seen that the density of the magnetic flux flowing through the wire has increased twice or more.

FIG. 5B shows the measured values of the geomagnetic drift amount. The measured values of the present example were compared with the measured values without the OMS and the measured values of the conventional example shown in FIG. Things. Here, the measurement of the amount of geomagnetic drift is performed, for example, as shown in FIG.
And a 360 ° rotation around the Y axis perpendicular to the magnetic field H (actually rotating the magnetic field) to measure the amount of geomagnetic drift. The amount of geomagnetic drift refers to a case where the CRT 110 is installed in a place where geomagnetism exists (in this example, the horizontal component of the geomagnetic field is set to approximately 30 μT) and is oriented in a 360 ° direction including north, south, east and west (demagnetization is performed every time the direction is changed). (Performed) is the maximum amount of movement of the electron beam in the horizontal direction (Peak to Peak value). The smaller this value is, the higher the magnetic shielding effect of the CRT 110 is.

In FIG. 5B, the unit of the geomagnetic drift amount is [μmp-p. ]. Also, the amount of geomagnetic drift at the Y-axis end shown in FIG.
The average drift amount at points 2 and 5 on the axis, and the geomagnetic drift amount at the corner is indicated by points 1 and 5 shown in FIG.
The average drift amount is 3, 4, or 6. As shown in FIG. 5B, in the OMS 160 of the present example and the conventional OMS shown in FIG. 6 surrounding the outer periphery of the CRT 110, the geomagnetic drift amount at the Y-axis end is equal, and the drift amount of the corner is 1 μm. It can be seen that although almost the same, it is possible to obtain almost the same magnetic shield characteristics. Also, from the comparison between the OMS 160 of the present example and the case without the OMS,
According to this example, it is understood that the geomagnetic drift amount is greatly reduced at both the Y-axis end and the corner, and the magnetic shielding performance is greatly improved.

[0025]

As described above, in the color video receiver according to the present invention, the OMS mounted on the outer periphery of the CRT is used.
Is composed of a pair of upper and lower plate members arranged corresponding to the degaussing coil, and each plate member is formed to substantially cover the degaussing coil, and is protruded from the main body portion toward the tube surface of the CRT. It had a shape having a protruding green portion. Therefore, CR
An OMS can be constructed simply by installing a plate at the top and bottom of the T, and the conventional OMS surrounding the outer periphery of the CRT
Compared with the above, it is possible to significantly reduce both material costs and processing costs.

The OMS plate according to the present invention has a protruding green portion protruding in the direction of the tube surface of the CRT from a main body having a shape substantially covering the degaussing coil. In addition, it is possible to obtain a much better magnetic shielding effect without affecting the magnetic field distribution of the deflection yoke and having no OMS (only the demagnetizing coil), and to provide a conventional OMS.
It is possible to obtain the magnetic shielding performance that is not much different from that of the magnetic shield.

[Brief description of the drawings]

FIG. 1 is a top view showing a configuration example of a color video receiver according to the present invention.

FIG. 2 is an exploded perspective view of the color video receiver shown in FIG.

3 is an abbreviated top view showing the internal structure of the CRT of the color video receiver shown in FIG.

FIG. 4 is a side sectional view showing an internal structure of a CRT of the color video receiver shown in FIG. 1;

5 is an explanatory diagram showing measured values of a magnetic east density and a geomagnetic drift amount in the color image receiver shown in FIG. 1 in comparison with a conventional color image receiver.

FIG. 6 is an exploded perspective view showing a configuration example of a conventional color video receiver provided with an OMS.

FIG. 7 is a perspective view showing a configuration example of a color video receiver provided with a conventional OMS different from FIG.

[Explanation of symbols]

110 CRT, 112 Funnel, 114
... face panel, 114A ... phosphor screen, 116 ... reinforcing metal fittings, 118 ... holder, 120 ... neck part, 12
2. Anode terminal, 124 ... AG, 124A ... Frame, 126 ... IMS, 150A, 150B ... Demagnetizing coil, 160 ... OMS, 162A, 162B ...
Plate body, 164A, 164B ... body part, 166A, 16
6B: Projecting green portion, 168: Notch portion.

Claims (5)

[Claims] 1. A cathode ray tube having an internal magnetic shield made of a ferromagnetic material, a pair of upper and lower demagnetizing coils attached to an outer peripheral portion of the cathode ray tube, and a ferromagnetic material attached to an outer peripheral portion of the cathode ray tube. In a color video receiver having an external magnetic shield, the external magnetic shield is composed of a pair of upper and lower plate members arranged corresponding to the degaussing coil, and each of the plate members is
A color video receiver comprising: a main body having a shape substantially covering the degaussing coil; and a protruding green portion protruding from the main body toward the surface of the cathode ray tube. 2. The color video image receiver according to claim 1, wherein the degaussing coil is arranged so as to be guided from inside the main body of the plate to outside the protruding green portion. 3. The apparatus according to claim 1, wherein an edge of said plate body on a neck side of said cathode ray tube extends to a position covering an opening of said internal magnetic shield on a neck side. Color video receiver. 4. The color video receiver according to claim 3, wherein said degaussing coil is disposed so as to protrude from an edge of said plate body on a neck side of said cathode ray tube. 5. The color video image receiver according to claim 3, wherein an edge of said plate body on a side of a neck portion of said cathode ray tube has a cutout for avoiding an anode terminal of said cathode ray tube.