JPH11233049A - Image displaying apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of suppressing effect caused by the difference of waveforms of unnecessarily radiated electric field and pulsed voltage with reverse polarity by installing a conductive electrode closely to or adjacently to a cathode-ray tube and providing a supply means for supplying integrated waveform voltage of inversely pulsed voltage with reverse polarity to that of the pulsed voltage supplied to a deflecting yoke. SOLUTION: A conductive electrode 18 is installed closely to or adjacently to the outer face of a large diameter part of a cathode-ray tube (a color television picture tube). At the time of operation, alternating electric fields 23, 23 are radiated from the front face of the color television picture tube synchronously with the saw-teeth like horizontally deflected electric current repeated in horizontal cycles and flowing in a horizontally deflecting coil of a deflecting yoke 2. In this case, the alternating electric field 23 is an unnecessarily radiated electric field and strained into an integrated waveform having attenuating property. On the other hand, the alternating electric field 24 is radiated from the conductive electrode 18 and stained into an integrated waveform having attenuating property and reverse polarity to that of the alternating electric field 23 and cancels the alternating electric field 23. Consequently, the unnecessary radiated electric field is effectively lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display apparatus in which unnecessary radiation electric fields radiated from the front surface of a cathode ray tube having a deflection yoke are reduced.

[0002]

2. Description of the Related Art As an image display device, a cathode ray tube is horizontal.
A deflection yoke having a vertical deflection coil is attached, and an electron beam emitted from the electron gun is deflected by a horizontal and vertical deflection magnetic field generated by the deflection yoke, and provided on an inner surface of a panel constituting a front portion of the cathode ray tube. Some display the image by scanning the phosphor screen horizontally and vertically.

Generally, in this image display device, a high-voltage pulse voltage is applied to a horizontal deflection coil of a deflection yoke to flow a sawtooth-like horizontal deflection current, thereby generating a deflection magnetic field.
A high-frequency alternating electric field is generated from the horizontal deflection coil due to the pulse voltage. Therefore, this alternating electric field
It has adverse effects such as malfunctioning of electronic devices installed near the image display device. In addition, there is a concern that an OA device operated close to the image display device may affect the human body. To suppress this unnecessary radiation electric field, MPR-
2 and TCO have been established. The MPR-2 is 2.5 V / m, and the TCO is 1.0 V / m or less.

[0004] The suppression of the unnecessary radiation electric field can be suppressed by simply arranging metal shields on the upper, lower, left, right and rear portions of the image display device so as to surround the cathode ray tube except for the front portion of the cathode ray tube. . On the other hand, the front part of the cathode ray tube can be suppressed by forming a transparent conductive film on the outer surface of the panel or disposing a shielding plate on which the transparent conductive film is formed.

As another means for suppressing the unnecessary radiation electric field,
A conductive electrode is attached to the cathode ray tube, and a pulse voltage having a polarity opposite to that of the pulse voltage supplied to the horizontal deflection coil is applied to the conductive electrode to generate an alternating electric field, and the alternating electric field generated from the conductive electrode Means for canceling the unnecessary radiation electric field have been proposed.

Japanese Patent Application Laid-Open No. 7-298169 discloses that
Conductive electrode attached to the cathode ray tube as a pulse voltage application means of the opposite polarity that effectively reduces the unnecessary radiation electric field. Are shown.

[0007]

As described above, as means for suppressing unnecessary radiated electric fields radiated from the front surface of the cathode ray tube to which the deflection yoke is attached, (a) a transparent conductive film is formed on the outer surface of the panel; Alternatively, a means for arranging a shielding plate formed with a transparent conductive film is applied. (B) A pulse voltage having a polarity opposite to that of the pulse voltage supplied to the horizontal deflection coil is applied to the conductive electrode attached to the cathode ray tube to generate an alternating electric field. Means for Generating (c) There is a means for applying, to a conductive electrode attached to a cathode ray tube, a reverse-polarity pulse voltage that has been subjected to differential conversion with a polarity opposite to that of a pulse voltage supplied to a horizontal deflection coil.

However, regarding the means (a) for forming a transparent conductive film or disposing a shielding plate on which the transparent conductive film is formed, it is necessary to form a transparent conductive film having a low resistance value in order to enhance the shielding effect. However, there is a problem that the cost increases due to the complexity and addition of the manufacturing process.

The means (b) for generating and canceling the alternating electric field is based on the difference in the geometric position between the conductive electrode and the source of the unnecessary radiated electric field, and the reverse of the unnecessary radiated electric field and the applied electric field to the conductive electrode. There is a problem that the suppression effect is low due to a difference in waveform from the polarity pulse voltage.

(C) The means for applying the differentially converted reverse polarity pulse voltage is suppressed by forming a voltage waveform that matches the waveform of the unnecessary radiation voltage radiated from the cathode ray tube to which the deflection yoke is attached. Although the effect can be enhanced, the unnecessary radiation electric field actually radiated from the cathode ray tube is
Waveforms that can be suppressed only by the differential waveform of the reverse-polarity pulse voltage due to differences in the internal impedance of the cathode ray tube, the relationship with the ground wire provided in the image display device, and the geometric positional relationship between the deflection yoke and the cathode ray tube. However, if the pulse voltage has an integral waveform having an attenuation characteristic, a sufficient suppression effect cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a reduction in suppression effect caused by a difference in waveform between an unnecessary radiated electric field radiated from a cathode ray tube having a deflection yoke and a reverse polarity pulse voltage. The purpose is to solve.

[0012]

In an image display apparatus having a cathode ray tube having a deflection yoke attached thereto, a conductive electrode is disposed in close contact with or near the cathode ray tube,
A supply unit is provided for supplying an integrated waveform voltage of a reverse pulse voltage having a polarity opposite to that of the pulse voltage supplied to the deflection yoke to the conductive electrode.

The supply means includes a resistor and a capacitor, and supplies one end of the resistor with a reverse pulse voltage having a polarity opposite to that of the pulse voltage supplied to the deflection yoke. The capacitor and the conductive electrode were connected, and the capacitor was connected to the ground.

The supply means includes a resistor and a variable capacitor, and supplies one end of the resistor with a reverse pulse voltage having a polarity opposite to that of the pulse voltage supplied to the deflection yoke. The variable capacitor and the conductive electrode were connected, and the variable capacitor was connected to the ground.

Further, the supply means is configured to supply to the conductive electrode a composite voltage of a reverse pulse voltage having a polarity opposite to the pulse voltage supplied to the deflection yoke and an integrated waveform voltage of the reverse pulse voltage.

Further, the supply means is formed so as to individually supply the conductive electrode with a reverse pulse voltage having a polarity opposite to the pulse voltage supplied to the deflection yoke and an integrated waveform voltage of the reverse pulse voltage.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a configuration of an image display device which is one embodiment of the present invention. This image display device includes a cathode ray tube 1, a deflection yoke 2 attached to the cathode ray tube 1, a high-voltage source for supplying a predetermined voltage to the cathode ray tube 1 and the deflection yoke 2.
It comprises a deflection circuit 3 and an integration circuit 4 (supply means) connected to the high voltage / deflection circuit 3.

FIG. 2 shows a color picture tube as an example of the cathode ray tube 1. This color picture tube has a vacuum envelope consisting of a panel 6 and a funnel 7, and the panel 6
A phosphor screen 8 composed of a three-color phosphor layer that emits blue, green, and red light is provided on the inner surface, and a shadow mask 9 is disposed inside and opposed to the phosphor screen 8. A metal reinforcing band 10 for preventing implosion of the vacuum envelope is attached to the outer periphery of the side wall of the panel 6. The metal reinforcing band 10 is electrically grounded. On the other hand, an electron gun 13 for emitting three electron beams is sealed in a neck 12 of the funnel 7. An anode terminal 15 is provided on the large diameter portion 14 of the funnel 7. Further, on the outer surface of the large-diameter portion 14 of the funnel 7, an outer conductive film 16 for adding capacitance to the anode of the color picture tube is provided, avoiding the anode terminal 15. The outer conductive film 16 is electrically grounded.

Further, in this color picture tube, a conductive electrode 18 is provided in close contact with or close to the outer surface of the large-diameter portion 14 of the funnel 7 closer to the phosphor screen 8 than the deflection yoke 2. This conductive electrode 18 is connected to the anode terminal 1.
5. Insulated from the outer conductive film 16, the metal reinforcing band 10, and the like.

The deflection yoke 2 is mounted outside the vicinity of the boundary between the neck 12 of the funnel 7 and the large-diameter portion 14 of the color picture tube. The deflection yoke 2 includes a horizontal deflection coil for generating a horizontal deflection magnetic field for horizontally deflecting the three electron beams emitted from the electron gun 13 and a vertical deflection coil for generating a vertical deflection magnetic field for vertically deflecting the three electron beams.

The high voltage / deflection circuit 3 includes a flyback transformer and horizontal and vertical deflection circuits. A high voltage DC voltage of about several tens of kV to 30 kV is supplied from the flyback transformer to the anode terminal 15 of the color picture tube via the terminal T3. Further, a sawtooth pulse voltage of about several hundreds to 1000 V is applied to the horizontal deflection coil of the deflection yoke 2 from the built-in horizontal and vertical deflection circuits via terminals T1 and T2.
2 are supplied repeatedly in a horizontal cycle. Also, a sawtooth pulse voltage is repeatedly supplied to the vertical deflection coil in a vertical cycle via a terminal (not shown).

The integrating circuit 4 includes a resistor 20 and a capacitor 2
1 is provided. One end of the resistor 20 is connected to the terminal T4 of the high voltage / deflection circuit 3, and the other end is connected to the capacitor 21 and the conductive electrode 18 provided on the outer surface of the large diameter portion 14 of the funnel 7. The capacitor 21
Grounded.

When the image display device is configured as described above,
In operation, alternating electric fields 23 and 24 are radiated from the front surface of the color picture tube in synchronization with a sawtooth-like horizontal deflection current repeated in a horizontal cycle flowing through the horizontal deflection coil of the deflection yoke 2.
The alternating electric field 23 is an unnecessary radiated electric field radiated due to the pulse voltage applied to the deflection yoke, and has a difference in the internal impedance of the color picture tube, a relation with a ground wire provided in the image display device, Due to the geometrical positional relationship between the deflection yoke and the color picture tube, the waveform is distorted into an integral waveform having an attenuation characteristic. On the other hand, the alternating electric field 24 has a polarity 25 opposite to the sawtooth pulse voltage which is supplied from the high voltage / deflection circuit 3 to the horizontal deflection coil and which is repeated in a horizontal cycle.
Is supplied to the integrating circuit 4 via the terminal T3, and the inverted integrated waveform voltage 26 converted by the integrating circuit 4 is supplied to the conductive electrode 18, whereby the electric field radiated from the conductive electrode 18 is there.

As shown in FIG. 3, the alternating electric field 24 radiated from the conductive electrode 18 is distorted into an integrated waveform having an attenuation characteristic of a polarity opposite to that of the alternating electric field 23.
And cancel each other out. Therefore, by configuring the image display device as described above, the unnecessary radiation electric field radiated from the horizontal deflection coil can be effectively reduced.

Next, another embodiment will be described.

In the above embodiment, a fixed-capacitance capacitor is connected to the integration circuit. FIG. 4 shows a configuration in which the capacitor 21 of the integration circuit 4 is a variable capacitor. When the capacitor 21 is constituted by a variable capacitor as described above, the time constant of the integration circuit 4 can be changed, and a time constant suitable for the attenuation characteristic of the waveform of the unnecessary radiated electric field radiated from the horizontal deflection coil can be easily selected. Thus, the unnecessary radiation electric field radiated from the horizontal deflection coil can be reduced more effectively.

In the above-described embodiment, the high-voltage / deflection circuit supplies the integration circuit with a pulse voltage having a polarity opposite to that of the sawtooth-shaped pulse voltage that is supplied to the horizontal deflection coil and that is repeated in a horizontal cycle, and the waveform is converted. From this integration circuit to the conductive electrode,
Although the configuration is such that a voltage of the opposite polarity converted into an integrated waveform is supplied, as shown in FIG. 5, a sawtooth-shaped repetition is performed from the high voltage / deflection circuit 3 to the integration circuit 4 at a horizontal cycle supplied to a horizontal deflection coil. A pulse voltage 25 having a reverse polarity to the pulse voltage is supplied, and a voltage obtained by combining the reverse polarity pulse voltage 25 from the high voltage / deflection circuit 3 and the integrated waveform voltage 26 converted by the integration circuit 4 is applied to the conductive electrode. May be supplied.

With this configuration, the unnecessary radiation electric field radiated from the horizontal deflection coil can be more effectively reduced.

As shown in FIG. 6, a high-voltage / deflection circuit 3 directly supplies a conductive electrode with a pulse voltage 25 having a polarity opposite to that of a sawtooth pulse voltage which is supplied to a horizontal deflection coil and is repeated in a horizontal cycle. And the reverse polarity pulse voltage 2
5 may be supplied to the integration circuit 4, and the integrated waveform voltage 26 obtained by the waveform conversion obtained from the integration circuit 4 may be supplied to the conductive electrode separately from the reverse polarity pulse voltage 25.

Even with this configuration, the unnecessary radiation electric field radiated from the horizontal deflection coil can be more effectively reduced.

Although the embodiment has been described with reference to an image display device including a color picture tube to which a deflection yoke is attached, the present invention is also applicable to an image display device having a cathode ray tube other than the color picture tube. is there.

[0033]

According to the present invention, in an image display apparatus provided with a cathode ray tube having a deflection yoke attached thereto, a conductive electrode is disposed in close contact with or near the cathode ray tube, and has a polarity opposite to the pulse voltage supplied to the deflection yoke. If a supply means for supplying an integrated waveform voltage of the reverse pulse voltage to the conductive electrode is provided, an integrated waveform having an attenuation characteristic radiated from the front surface of the cathode ray tube by applying a pulse voltage to the horizontal deflection coil of the deflection yoke An unnecessary radiation electric field composed of a distorted AC electric field can be efficiently and sufficiently suppressed by an integrated waveform voltage similar to the reverse pulse voltage.

The supply means includes a resistor and a variable capacitor, and supplies one end of the resistor with a reverse pulse voltage having a polarity opposite to that of the pulse voltage supplied to the deflection yoke. By connecting to the variable capacitor and the conductive electrode and connecting this variable capacitor to the ground, it is possible to easily select a time constant that matches the attenuation characteristics of the waveform of the unnecessary radiated electric field radiated from the horizontal deflection coil. An optimal integrated waveform voltage of the reverse pulse voltage can be generated for each image display device, and a high-quality image display device can be configured.

Further, the supply means is configured to supply to the conductive electrode a composite voltage of a reverse pulse voltage having a polarity opposite to the pulse voltage supplied to the deflection yoke and an integrated waveform voltage of the reverse pulse voltage, In addition, by forming a reverse pulse voltage having a polarity opposite to that of the pulse voltage supplied to the deflection yoke and an integrated waveform voltage of the reverse pulse voltage individually to the conductive electrodes, radiation is radiated from the horizontal deflection coil. A high-quality image display device that further effectively reduces unnecessary radiation electric fields can be configured.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an image display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a color picture tube constituting the image display device.

FIG. 3 is a diagram showing a relationship between an unnecessary radiation electric field radiated from a front surface of a color picture tube constituting the image display device and an alternating electric field due to a reverse pulse voltage.

FIG. 4 is a diagram showing a configuration of an integration circuit of an image display device according to another embodiment of the present invention.

FIG. 5 is a diagram illustrating a main configuration of an image display apparatus according to another embodiment of the present invention.

FIG. 6 is a diagram showing a main part configuration of an image display device according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Color picture tube 2 ... Deflection yoke 18 ... Conductive electrode 20 ... Resistor 21 ... Condenser

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // G09G 5/00 550 G09G 5/00 550A

Claims (5)

[Claims] 1. An image display apparatus comprising a cathode ray tube having a deflection yoke attached thereto, wherein a conductive electrode is disposed in close contact with or near the cathode ray tube, and the pulse voltage supplied to the deflection yoke is An image display device comprising: a supply unit that supplies an integrated waveform voltage of a reverse pulse voltage having a reverse polarity to the conductive electrode. 2. A supply means comprising a resistor and a capacitor, wherein one end of the resistor is supplied with a reverse pulse voltage having a polarity opposite to the pulse voltage supplied to the deflection yoke, and the other end of the resistor is connected with the capacitor. And connected to the conductive electrode,
2. The image display device according to claim 1, wherein said capacitor is connected to ground. 3. The supply means includes a resistor and a variable capacitor, and one end of the resistor is supplied with a reverse pulse voltage having a polarity opposite to the pulse voltage supplied to the deflection yoke, and the other end of the resistor has the other end. 2. The image display device according to claim 1, wherein the image display device is connected to a variable capacitor and a conductive electrode, and the variable capacitor is connected to a ground. 4. The supply means is configured to supply to the conductive electrode a composite voltage of a reverse pulse voltage having a polarity opposite to the pulse voltage supplied to the deflection yoke and an integrated waveform voltage of the reverse pulse voltage. The image display device according to claim 1, wherein: 5. The supply means is configured to supply a reverse pulse voltage having a polarity opposite to the pulse voltage supplied to the deflection yoke and an integral waveform voltage of the reverse pulse voltage to the conductive electrode individually. The image display device according to claim 1, wherein: