JPH11298912A - Landing correction device and method for installing earth magnetism sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate for landing in the valiation when directed to east and west. SOLUTION: A detection signal Vt-out and a reference voltage vref from an earth magnetism sensor 1 are fed to a drive circuit 2, and the detection signal Vy-out is fed to an absolute value circuit 21 for generating a looped-back signal based on the reference voltage Vref . Furthermore, a signal from the absolute value circuit 21 is fed to a power modulation section 23 via an amplifier 22. For example, a horizontal drive signal of a picture tube is fed to a switching element 25 via a synchronization phase adjustment circuit 24 to apply on/off control to the switching element 25. Thus, a sawtooth wave is generated between the element 25 and a resonance capacitor 26 and the amplitude of the sawtooth wave is adjusted by a power supply voltage from the power modulation section 23. Then the sawtooth wave signal, whose amplitude is adjusted is fed to a east-west directed compensating coil 3 via a polarity switching device 27.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a landing correction device suitable for use in, for example, a television receiver having a large cathode ray tube and a method of installing a geomagnetic sensor. In detail, the direction in which the cathode ray tube is installed is detected, and a correction current corresponding to the orientation is supplied to a compensation coil provided in a ring shape around the display surface of the cathode ray tube, thereby compensating for landing fluctuation due to the influence of terrestrial magnetism. Things.

[0002]

2. Description of the Related Art Generally, a magnetic field due to the earth's magnetism exists on the earth, and its direction and strength vary depending on the region.
Therefore, when a picture receiver using a picture tube (cathode ray tube) is placed in such a magnetic field, the trajectory of the electron beam is bent by the influence of the magnetic field, and so-called mislanding occurs. Such mislanding causes problems such as a decrease in color purity.

Here, geomagnetism is divided into a vertical geomagnetic component and a horizontal geomagnetic component. Depending on the vertical geomagnetic component among them, a substantially constant lateral beam movement is caused in the entire screen. However, in this case, the displacement due to the perpendicular geomagnetic component does not change regardless of the direction in which the picture tube is oriented, and it is considered that there is no practical problem by correcting the displacement in advance with a purity magnet or the like.

On the other hand, a horizontal geomagnetic component causes a problem in a fixed method such as the above-mentioned purity magnet because the trajectory of the electron beam changes when the direction of the picture tube is changed. Therefore, in a conventional apparatus, an external magnetic field is shielded by providing a magnetic shield outside or inside a funnel portion of a picture tube, for example, so as not to be affected by geomagnetism.

[0005] However, the shielding effect of such a magnetic shield is not perfect, and the effect is only reduced. In general, the influence of such geomagnetism is large in a large picture tube. Therefore, it is difficult to remove the influence as necessary and sufficiently only by the above-described magnetic shield. .

[0006]

Therefore, the applicant of the present application has given the following effect on the influence of geomagnetism on such a large picture tube.
For example, a means for compensating for the influence of terrestrial magnetism by installing a plurality of compensation coils around the display surface of a picture tube or in a funnel portion and applying a predetermined DC current to each of these compensation coils has been proposed (Japanese Patent Application No. 8-108). No. 320315).

That is, when such a picture tube is installed, for example, facing south, the electron beam is rotated clockwise under the influence of geomagnetism as shown on the left side of FIG. As shown in FIG. Therefore, a direct current can be passed through the compensation coil, and the magnetic field generated by this current can rotate the electron beam in a counterclockwise direction (right-hand rule) to restore the landing.

Similarly, when the picture tube is installed facing north, the electron beam is rotated counterclockwise under the influence of geomagnetism as shown on the left side of FIG. Is affected by a constant magnetic field in a certain direction. Therefore, in this case, it is possible to reverse the polarity of the DC current flowing through the above-described compensating coil so that the magnetic field generated by this current rotates the electron beam clockwise to restore the landing.

Further, when the picture tube is installed facing east and west, there is a magnetic field effect in which the polarity is reversed left and right around the center of the tube surface. Therefore, the landing pattern in this case has a horizontal magnetic field of 0 [A / A] as shown in FIG.
m], the direction in which the electron beam moves in the left and right directions is different from that in the case of FIG.

Therefore, such a mislanding cannot be compensated even if a direct current is supplied to a single compensation coil, for example. On the other hand, in the above-mentioned prior application, the compensation of the east-west direction geomagnetic component is performed by installing a plurality of compensation coils in the funnel portion of the picture tube and adding the magnetic field vectors generated by the plurality of compensation coils. This system compensates for mislanding due to geomagnetism.

However, the prior-art apparatus requires a plurality of compensation coils for compensating for the east-west direction geomagnetic component and a plurality of drive circuits for driving these coils. Therefore, the circuit configuration is complicated, the manufacturing cost is increased, and the adjustment is also complicated.

Further, in the above-mentioned conventional configuration, a changeover switch for inverting the polarity of the direct current when the electric power is directed to the north and south is required. Further, switching and adjustment of these switches must be performed by a user.

This application has been made in view of the above points, and the problem to be solved is that a conventional apparatus uses a plurality of compensation coils for compensating for a terrestrial magnetic component when the east and west directions are directed. And a configuration such as its drive circuit are required,
In addition, a changeover switch for reversing the polarity of the direct current is required when the vehicle is directed to the north and south, and the user has to perform switching and adjustment of these circuits and switches.

[0014]

Therefore, in the present invention, the direction in which the cathode ray tube is installed is detected, and a correction current having a direct current and / or a sawtooth waveform corresponding to the orientation is detected around the display surface of the cathode ray tube. In this case, it is possible to satisfactorily compensate for the fluctuation of the landing caused by the influence of terrestrial magnetism when the cathode ray tube is oriented in the north-south and / or east-west directions. it can.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the first embodiment of the present invention, a ring-shaped compensation coil is provided around the display surface of a cathode ray tube, and a geomagnetic sensor for detecting the orientation of the cathode ray tube is provided. And a sawtooth waveform current having a period synchronized with a direct current and / or a horizontal deflection is supplied to a compensation coil according to a detection signal from a geomagnetic sensor.

According to a second embodiment of the present invention, a geomagnetic sensor is installed in a cathode ray tube having a built-in magnetic shield so as to be perpendicular to a vertical magnetic field of geomagnetism deformed by the magnetic shield. It is.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram illustrating a configuration of an example of a landing correction device to which the first embodiment of the present invention has been applied.

In FIG. 1, a geomagnetic sensor 1 for detecting geomagnetism is provided. The geomagnetic sensor 1 is provided integrally with, for example, a picture tube (not shown). When the picture tube is installed, the geomagnetism in the installation direction is separately detected in the X-axis direction and the Y-axis direction. Things.

The detection signal V _{Y-OUT in the Y-} axis direction from the geomagnetic sensor 1 and the reference potential V _ref are supplied to the driving circuit 2.
Is supplied to the compensation coil 3 in the east-west direction. Further, the detection signal V _{X-OUT in the X-} axis direction from the geomagnetic sensor 1 and the reference potential V _ref are supplied to the drive circuit 4 (automatic inversion amplifying circuit 40), and the formed drive signal is supplied to the north-south compensation coil. 5 is supplied.

Here, for example, the detection signal V _Y-OUT from the geomagnetic sensor 1 is taken out with respect to the reference potential V _ref as shown in FIG. 2A, for example. Therefore, this detection signal V
_{The Y-OUT} is supplied to the absolute value circuit 21 in the drive circuit 2 to form a signal folded on the basis of the reference potential _Vref as shown in FIG. 2B. Further, the absolute value circuit 21
Is supplied to the power supply modulation unit 23 through the amplifier 22.

On the other hand, for example, a horizontal drive signal for a picture tube (not shown) is supplied to a synchronous phase adjustment circuit 24 in the drive circuit 2.
Supplied to Then, a signal having a cycle synchronized with the adjusted horizontal deflection is supplied to the switching element 25, and the switching element 25 is turned on / off, thereby forming a saw-tooth waveform with the resonance capacitor 26. Further, the amplitude of the sawtooth waveform is the same as that of the power supply
3 is adjusted by the power supply voltage.

The sawtooth waveform signal whose amplitude has been adjusted is
It is supplied to the east-west compensation coil 3 through the polarity switch 27. The operations of the switching element 25, the resonance capacitor 26, and the compensation coil 3 are the same as those of a general deflection circuit. That is, the sawtooth waveform is formed by regarding the compensation coil 3 as a deflection coil. The capacitor 28 plays the role of an S-shaped correction capacitor.

In this circuit, for example, in FIG.
With respect to the mislanding as shown in FIG. 11B, a driving current having a sawtooth waveform as shown in FIG. by this,
In the portions A, B, and C in the figure, for example, A, B in FIG.
Compensation magnetic fields as shown in B and C are generated, and the above-mentioned mislanding is compensated.

FIG. 5 shows a specific circuit configuration. In FIG. 5, the absolute value circuit 21 is a differential amplifier 1
1, 12 and these differential amplifiers 11, 1
2, the detection signal _VY-OUT is folded back with respect to the reference potential _Vref and extracted. The amplifier 22 is configured by the differential amplifier 13, and a signal from the absolute value circuit 21 is amplified and taken out with respect to the reference potential _Vref .

The signal from the amplifier 22 is supplied to the power supply modulation section 2
3 is supplied. The power supply modulator 23 has a so-called series regulator configuration. And amplifier 2
2 is supplied to the active element 15 through the differential amplifier 14, and the active element 15 is controlled in accordance with the signal, so that a desired power supply voltage is extracted through the choke coil 16.

The synchronizing phase adjusting circuit 24 is constituted by, for example, a one-shot multivibrator IC 17, and the phase of the supplied horizontal drive signal (HD) is adjusted by setting an arbitrary constant. This signal is supplied to the switching element 25, and a deflection circuit is formed by the switching element 25, the resonance capacitor 26, and the compensation coil 3 to form a sawtooth waveform.

Further, the above-described detection signal V _Y-OUT and reference potential V _ref are supplied to a differential amplifier 18 constituting, for example, a hysteresis comparator. Thus, a signal which becomes "1" when the picture tube (not shown) faces the east side is extracted from the differential amplifier 18, for example. This signal is supplied to the solenoid of the relay constituting the polarity switching device 27, and the polarity of the signal supplied to the compensation coil 3 is switched.

FIG. 6 shows another example of a means for generating a sawtooth waveform by the switching element 25 or the like. This figure 6
In this case, a bipolar transistor is used as the switching element 25. In this case, by providing a damper diode 29 in parallel with the bipolar transistor as the switching element 25, a saw-tooth waveform similar to that of the above-described circuit can be generated.

FIG. 7 shows an automatic polarity inverting amplifier circuit 4.
0 shows a specific circuit configuration. 7A, the reference potential V _ref from the geomagnetic sensor 1 is connected to the non-inverting inputs of the differential amplifiers 41 and 42, respectively, and the north-south compensation coil 5 is connected between the outputs of the differential amplifiers 41 and 42. Is connected. Then, the detection signal V _{X-OUT in the X-} axis direction from the geomagnetic sensor 1 is connected to the outputs of the differential amplifiers 41 and 42 through resistors 43, 44 and 45 and 46, respectively, and these resistors 43, 44 and 45, The connection middle point of 46 is connected to the inverting inputs of the differential amplifiers 41 and 42, respectively.

In this circuit, the output potential E ₀₁ of the differential amplifier 41 is E ₀₁ = V _ref + R 2 / R 1 (V _ref −) where R ₁ is the resistance of the resistor 43 and R 2 is the resistance of the resistor 44. V _X-OUT ). Similarly, the output potential E of the differential amplifier 42
_02, the resistance value of the resistor 45 R3, the resistance value of the resistor 46 at the R4, is represented by _{E 02 = V ref + R4 /} R3 (V ref -V X-OUT).

Therefore, these resistance ratios R2 / R1 and R4 /
By selecting R3 to an appropriate value, the compensation coil 5
, The potential difference E _{N / S} = E ₀₁ −E ₀₂ can be arbitrarily changed. That is, when the detection signal V _{X-OUT in the X-} axis direction with respect to the reference potential V _ref is changed, the potential difference E _{N / S} = E ₀₁ -E ₀₂ applied to the compensation coil 5 is automatically inverted to positive and negative polarities and becomes arbitrary. Is changed to

That is, for example, R2 / R1 = 2/3, R4
/ R3 = _2/15 and V _ref = 2.5, V
_X-OUT = than 4V E when _{01 = 2.5 + 2/3 (} 2.5-4) = 1.5 E 02 = 2.5 + 2/15 (2.5-4) = 2.3, E N / _S = E ₀₁ -E ₀₂ = -0.8V, and the case of _{V X-OUT = 1V E 01} = 2.5 + 2/3 (2.5-1) = 3.5 E 02 = 2.5 + 2/15 ( from 2.5-1) = 2.7, becomes _{E N / S = E 01 -E} 02 = 0.8V, the polarity is reversed.

It should be noted that the above-described polarity automatic inversion amplifier circuit 40
For example, it can also be realized with a circuit configuration as shown in FIG. In this circuit configuration, the polarity can be inverted as described above.

FIG. 8 shows a specific configuration when the compensation coils 3 and 5 are provided in a picture tube. That is, FIG.
8A shows a perspective view of the appearance of the image receiver, and FIG. 8B shows a cross-sectional view of a main part. In these figures, a so-called beznet 102 is provided around the display surface 101 of the picture tube 100, and the display surface 101 of the picture tube 100 is provided inside or inside the beznet 102 or at a position b.
Are provided so as to surround.

Therefore, in this apparatus, the orientation in which the cathode ray tube is installed is detected, and a direct current and / or a saw-tooth waveform correction current corresponding to the orientation is detected by a compensation coil provided in a ring shape around the display surface of the cathode ray tube. By flowing, it is possible to satisfactorily compensate for landing fluctuations due to the influence of geomagnetism when the cathode ray tube is oriented in the north-south and / or east-west directions.

Thus, the conventional device requires a plurality of compensating coils and a driving circuit for compensating for the terrestrial magnetism component when traveling east and west. A changeover switch for inversion was required, and further, the user had to perform switching and adjustment of these circuits.
According to the present invention, these problems can be easily solved.

The circuits for generating the east-west and north-south compensation magnetic fields can be used independently only in the east-west direction or only in the north-south direction, for example, depending on the compensation contents required for the picture tube.

FIG. 9 is a diagram for explaining a method of installing a geomagnetic sensor according to a second embodiment of the present invention. In FIG. 9, for example, when mounting a device that only compensates for mislanding due to north-south geomagnetism, a vertical magnetic field is twisted by an inner magnetic shield (IMS) in a picture tube, for example, as shown in FIG. May be detected by the geomagnetic sensor 1 described above.

Therefore, in order to solve such a problem,
For example, as shown in the drawing, the geomagnetic sensor 1 is installed so as to be perpendicular to the vector of the twisted vertical magnetic field, thereby canceling the twisted vertical magnetic field. In this way, the twisted vertical magnetic field can be prevented from being detected. However, in this method, the detection amount of the horizontal magnetic field is slightly reduced, but the same correction as in the case where the sensor is installed horizontally can be performed by changing the amplification factor and the like on the circuit side.

Thus, according to the above-described landing correction device of the present invention, a ring-shaped compensation coil is provided around the display surface of the cathode ray tube, and a geomagnetic sensor for detecting the direction in which the cathode ray tube is installed is provided. By flowing a sawtooth waveform current having a cycle synchronized with DC and / or horizontal deflection in accordance with the detection signal from the compensation coil,
It is possible to satisfactorily compensate for variations in landing caused by the influence of terrestrial magnetism when the cathode ray tube is oriented in north-south and / or east-west directions.

According to the above-described method for installing a geomagnetic sensor according to the present invention, a geomagnetic sensor is provided so that a cathode ray tube having a built-in magnetic shield is perpendicular to a vertical magnetic field of the geomagnetism deformed by the magnetic shield. Is installed, the twisted vertical magnetic field can be prevented from being detected even when the vertical magnetic field is twisted by, for example, an inner magnetic shield (IMS) in the picture tube.

The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0043]

Thus, according to the first aspect of the present invention, the direction in which the cathode ray tube is installed is detected, and the direct current and / or the corresponding direction are detected.
Or, by flowing a correction current having a sawtooth waveform through a compensation coil provided in a ring shape around the display surface of the cathode ray tube, a landing fluctuation due to the influence of geomagnetism when the cathode ray tube is oriented in the north-south and / or east-west directions. Can be satisfactorily compensated for.

As a result, the conventional apparatus requires a plurality of compensating coils and a driving circuit for compensating for the terrestrial magnetic component when traveling east and west. A changeover switch for inversion was required, and further, the user had to perform switching and adjustment of these circuits.
According to the present invention, these problems can be easily solved.

According to the seventh aspect of the present invention, even when the vertical magnetic field is twisted, the inner magnetic shield (IMS) in the picture tube prevents the twisted vertical magnetic field from being detected. You can do it.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an example of a landing correction device to which the present invention is applied.

FIG. 2 is a diagram for explaining the operation.

FIG. 3 is a diagram for explaining this.

FIG. 4 is a diagram for explaining this.

FIG. 5 is a connection diagram of an example of a specific circuit of the present invention.

FIG. 6 is a connection diagram of a main part of another example of the specific circuit of the present invention.

FIG. 7 is a connection diagram of a main part of an example of a specific circuit of the present invention.

FIG. 8 is a diagram for explaining a specific configuration thereof.

FIG. 9 is a diagram for explaining a method of installing a geomagnetic sensor to which the present invention is applied.

FIG. 10 is a diagram for explaining a conventional device.

FIG. 11 is a diagram for explaining a conventional device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Geomagnetic sensor which detects terrestrial magnetism, 2,5 ... Drive circuit, 3 ... East-west direction compensation coil, 5 ... South-north direction compensation coil, 21 ... Absolute value circuit, 22 ... Amplifier, 23 ... Power supply modulation part, 24 ... Synchronous phase adjustment circuit, 25: switching element, 26: resonance capacitor, 27: polarity switcher, 2
8. Capacitor 28, 40 ... Automatic polarity inverting amplifier circuit

Claims (7)

[Claims] 1. A ring-shaped compensation coil is provided around a display surface of a cathode ray tube, and a geomagnetic sensor is provided for detecting an orientation at which the cathode ray tube is installed. /
Alternatively, a landing correction device, wherein a sawtooth waveform current having a cycle synchronized with horizontal deflection is supplied to the compensation coil. 2. The landing correction device according to claim 1, wherein first and second differential amplifiers are provided for the north-south direction component of the detection signal, and the north-south direction component and a reference potential at the midpoint thereof are provided. And the first
And forming a DC current that changes positively and negatively between the outputs of the first and second differential amplifiers by supplying the DC current to the output of the first and second differential amplifiers, and flowing the formed DC current to the compensation coil. Landing correction device. 3. The landing correction device according to claim 1, wherein a DC current that changes in a positive or negative direction with respect to a north-south component of the detection signal is formed, and the formed DC current is supplied to one compensation coil. A landing correction device characterized by flowing. 4. The landing correction device according to claim 1, wherein a saw-tooth waveform current having a cycle synchronized with horizontal deflection whose amplitude and polarity is controlled is formed for the east-west direction component of the detection signal. A landing correction device, wherein the formed sawtooth waveform current flows through the compensation coil. 5. The landing correction device according to claim 1, wherein a saw-tooth waveform current having a cycle synchronized with horizontal deflection whose amplitude and polarity is controlled is formed for the east-west direction component of the detection signal. A landing correction device, wherein the formed saw-tooth waveform current is caused to flow through one compensation coil. 6. The landing correction device according to claim 1, wherein a DC current that changes in a positive or negative direction with respect to a north-south direction component of the detection signal, and an amplitude and a polarity of the DC current that changes with respect to an east-west direction component of the detection signal. A sawtooth waveform current having a cycle synchronized with the controlled horizontal deflection is formed, and the formed direct current and / or a sawtooth waveform current having a cycle synchronized with the horizontal deflection is caused to flow through the compensation coil. A landing correction device for performing correction. 7. An installation of a geomagnetic sensor, wherein a geomagnetic sensor is installed in a cathode ray tube having a built-in magnetic shield so as to be perpendicular to a vertical magnetic field of the geomagnetism deformed by the magnetic shield. Method.