JPH0566726A - Landing correcting device - Google Patents

Abstract

PURPOSE:To surely evade the influence of an external magnetic field with simple constitution by supplying a current for magnetic field formation to a Helmholtz coil so as to cancel the external magnetic field in first and second directions based on the magnetic field detection result in first and second directions intersected orthogonally with each other. CONSTITUTION:In a display device using a cathode ray tube, the magnetic field detection results S1, S2 in the first and second directions (x), (y) of a magnetic sensor 2 are integrated by the respective operational amplifier circuits 10, 11 and the detection signals SD 1, SD 2 varying the signal level in accordance with the magnitude of a synthetic magnetic field and the direction are obtained. After these detection signals SD 1, SD 2 are subjected to a voltage/ current conversion by operational amplifier circuits 28, 30, the magnetic field is formed to be '0' at the synthetic magnetic field by being outputted to the Helmholtz coils 33, 34, 43, 44 forming the magnetic field so as to cross the cathode ray tube in the first and second direction. Thus even when the display device is mounted on a traffic means, for example, a vessel, etc., and is moved to several places, the display picture can be formed in the state that the external magnetic field is '0'.

Description

Detailed Description of the Invention

[0001]

[Table of Contents] The present invention will be described in the following order. Field of Industrial Application Conventional Technology Problem to be Solved by the Invention Means for Solving the Problem (FIG. 1) Action (FIG. 1) Example (1) Configuration of Example (FIGS. 1 to 6) (2) Operation of Embodiment (3) Effect of Embodiment (4) Other Embodiment (FIG. 7) Effect of Invention

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a landing correction device, and is particularly applicable to a display device using a cathode ray tube.

[0003]

2. Description of the Related Art Conventionally, in a display device using a cathode ray tube, an external magnetic field such as terrestrial magnetism can be blocked or corrected.

That is, in the case of blocking the external magnetic field, shield materials are arranged inside and outside the cathode ray tube.

On the other hand, when correcting the external magnetic field,
Coil for landing correction (LCC)
coil) is arranged at a predetermined position, and a current according to the correction amount is supplied to the landing correction coil. As a result, in this type of display device, mislanding and screen distortion due to the influence of geomagnetism and the like can be effectively avoided.

[0006]

However, when the external magnetic field is cut off, no shielding material can be arranged for the display screen, terminals, etc. of the cathode ray tube, and in this type of display device, the cathode ray tube is completely removed. It cannot be magnetically shielded. Also,
It is necessary to use a material having a high magnetic permeability as the shield material, and there is a drawback that the weight of the entire display device is increased. In the end, the method of blocking the external magnetic field still has a problem in practical use.

On the other hand, when the landing correction coil is used, the external magnetic field can be corrected only locally, and when the external magnetic field is corrected as a whole of the cathode ray tube, a plurality of landing correction coils must be used after all. .. Therefore, the structure of the display device becomes complicated, and the correction range interferes between the landing correction coils, and even if mislanding can be corrected, screen distortion occurs.

The present invention has been made in consideration of the above points, and it is an object of the present invention to propose a landing correction device capable of reliably avoiding the influence of an external magnetic field with a simple structure.

[0009]

In order to solve the above problems, according to the present invention, Helmholtz coils 33, 34 and 43 for forming a magnetic field across a cathode ray tube in first and second orthogonal directions x and y. , 44, and magnetic sensors 2X and 2Y that are arranged so as to be surrounded by Helmholtz coils 33, 34, 43, and 44, and that output magnetic field detection results S1 and S2 in the first and second directions x and y, respectively.
A magnetic field correction circuit that supplies a magnetic field forming current I to the Helmholtz coils 33, 34, 43, 44 so as to cancel the external magnetic field Φ2 in the first and second directions x and y based on the magnetic field detection results S1 and S2. 8 to 47.

[0010]

The magnetic field forming current I is supplied to the Helmholtz coils 33, 34, 43, 44 so as to cancel the external magnetic field Φ2 in the first and second directions x and y based on the magnetic field detection results S1 and S2. If so, it is possible to reliably avoid the influence of the external magnetic field with a simple configuration.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the drawings.

(1) Configuration of the Embodiment In FIG. 1, reference numeral 1 denotes the landing correction device as a whole, and the combined magnetic field of the geomagnetism and the correction magnetic field in the x and y directions is detected by the geomagnetic sensors 2X and 2Y, respectively, and the detection result is shown. A correction magnetic field is generated based on

That is, as shown in FIG. 2, the landing correction device 1 is mounted on a display device 4 having a color cathode ray tube to avoid the influence of the geomagnetism on the cathode ray tube.

Here, the geomagnetic sensors 2X and 2Y are formed by winding a drive winding 2D and a detection winding 2P on a ring-shaped core 2C, and the drive winding 2D is as shown in FIG. The winding is performed so as to form a magnetic flux Φ1 that surrounds the ring-shaped core 2C. On the other hand, the detection winding 2P is wound so as to traverse the entire ring-shaped core 2C in the diametrical direction, and when a current is supplied to the detection winding 2P, the detection winding 2P is wound. A magnetic flux Φ2 that traverses the ring-shaped core 2C is formed in a direction orthogonal to the line 2P.

As a result, the geomagnetic sensors 2X and 2Y are concerned.
In the above, when the magnetic flux Φ1 that circulates around the core 2C is formed by the drive winding 2D, a portion where the magnetic flux Φ1 reinforces the external magnetic field (that is, corresponding to the magnetic flux Φ2) in the direction orthogonal to the detection winding 2P (in this case). In the portion indicated by the symbol A), the ring-shaped core 2C is saturated.

Here, the geomagnetic sensor 2X includes the detection winding 2
The direction orthogonal to P is the front-back direction of the display device 4 (symbol x
(Represented by the symbol), the display device 4 is arranged so as to avoid the cathode ray tube at a substantially central position. On the other hand, in the geomagnetic sensor 2Y, the direction orthogonal to the detection winding 2P is the left-right direction of the display device 4 (denoted by the symbol y).
So that it is arranged close to the geomagnetic sensor 2X.

Further, in the geomagnetic sensors 2X and 2Y, the commercial power source 6 is connected to the drive winding 2D, whereby the magnitudes of the external magnetic fields in the x and y directions are respectively passed through the detection winding 2P. And the detection signals S1 and S2 whose amplitude changes according to the direction.

In the landing correction device 1, the detection signal S1 is applied to the inverting input terminal of the operational amplifier circuit 10 via the resistor 8 and the detection signal S1 is applied to the inverting input terminal of the operational amplifier circuit 11 via the resistor 9. Operational amplifier circuits 10 and 11
Is a resistor 12, a variable resistor 14, and
The offset voltage formed by the resistors 16 and 18, the variable resistor 20, and the resistor 22 is input, and the output signal thereof is fed back to the inverting input terminal by the feedback capacitors 24 and 25.

As a result, the operational amplifier circuits 10 and 11 are
The detection signals S1 and S2 are integrated to detect the detection signals SD1 and SD2 whose DC level changes according to the magnitude and direction of the magnetic field Φ2.

Here, in the geomagnetism, it can be decomposed into a vertical component force and a horizontal component force, and the horizontal component force extends north and south at a predetermined declination angle. Therefore, the geomagnetic sensor 2
When X and 2Y are arranged, an external magnetic field Φ interlinking with the magnetic sensors 2X and 2Y at various places according to the orientation of the display device 4 concerned.
The size of 2 changes.

As a result, as shown in FIG. 4, in the landing correction device 1, the detection signal SD in which the direct current level changes by 90 degrees in phase depending on the direction of the display device 4 changes.
1 and SD2 (that is, the relationship between the sine and the cosine with respect to the azimuth (FIGS. 4A and 4B)) can be obtained.

The landing correction device 1 includes a selection circuit 26.
The detection signals SD1 and SD2 are applied to the operational amplifier circuits 28 and 30, respectively, via the. Here, the operational amplifier circuit 28 receives the detection signal SD1 at its inverting input terminal via the input resistor 31, and feeds back its output signal via the parallel circuit of the Helmholtz coils 33, 34 and the capacitor 35 and the feedback resistor 36. Has been done. On the other hand, the parallel circuit of the Helmholtz coils 33 and 34 and the capacitor 35 is configured to be grounded via the resistor 37, whereby the operational amplifier circuit 28 converts the detection signal SD1 into voltage and current, and the Helmholtz coil 33. , 34 are driven.

On the other hand, the operational amplifier circuit 30 receives the detection signal SD2 at its inverting input end via the input resistor 41, and outputs it via the parallel circuit of the Helmholtz coils 43 and 44 and the capacitor 45 and the feedback resistor 46. It is designed to return signals. On the other hand, the parallel circuit of the Helmholtz coils 43 and 44 and the capacitor 45 includes a resistor 47.
The operational amplifier circuit 30 converts the detection signal SD2 into a voltage and a current to drive the Helmholtz coils 43 and 44.

Here, the Helmholtz coils 33 and 34 are
This is a large rectangular coil together with the Helmholtz coils 43 and 44, and is wound a predetermined number of times and arranged along the inside corner of the cabinet of the display device 4.

At this time, as shown in FIG. 5, the Helmholtz coils 33, 34 are arranged in front of and behind the display device 4, driven by the output signal of the operational amplifier circuit 28, and detected by the geomagnetic sensor 2X. The magnetic field for correction is formed so as to cancel. On the other hand, as shown in FIG. 6, the Helmholtz coils 43 and 44 are arranged on the left and right of the display device 4 and driven by the output signal of the operational amplifier circuit 30 to cancel the external magnetic field detected by the geomagnetic sensor 2Y. A correction magnetic field is formed on the.

As a result, in the landing correction device 1, the Helmholtz coils 33, 3 are arranged so that the magnetic flux Φ2 detected by the geomagnetic sensors 2X and 2Y becomes zero.
4, 43, and 44 are driven.

Therefore, in the cathode ray tube, even when the orientation of the display device 4 is changed or when the display device is mounted on a transportation means such as a ship or an aircraft and moved in various places, the external magnetic field 0 is eliminated. It is possible to form a display image in a state, with a simple configuration, not to mention mislanding,
Screen distortion can be effectively avoided.

Further, by forming a feedback loop loop as a whole to cancel the external magnetic field, it is possible to cancel the external magnetic field other than the earth magnetism, and the effect of the external magnetic field can be effectively avoided.

Further, the adjustment work as in the case of using the landing correction coil can be omitted, and the display device 4 can be used accordingly.
The assembly work of can be simplified.

Further, in the landing correction device 1, by switching the contacts of the selection circuit 26 according to a predetermined switching signal SD, the terminal voltage of the input resistors 31 and 41 is set to 0 [V] during the degaussing operation of the cathode ray tube. It is designed to hold. As a result, in the landing correction device 1, the driving of the Helmholtz coils 33, 34, 43, 44 can be stopped during the degaussing operation of the cathode ray tube, and the cathode ray tube can be surely degaussed.

(2) Operation of the embodiment With the above configuration, the Helmholtz coils 33, 34,
43 and 44 are driven by the operational amplifier circuits 28 and 30 to form a magnetic field determined by the current I and the number of windings n, whereby the Helmholtz coil 3 is provided inside the display device 4.
The combined magnetic field Φ2 of the correction magnetic field and the geomagnetism formed by 3, 34, 43, and 44 is formed. Geomagnetic sensor 2 here
X and 2Y are driven by the commercial power source 6, and the detection signal S1 and the detection signal S1 whose amplitude changes with respect to the combined magnetic field Φ2 in accordance with the sizes and directions of the front-rear direction component and the left-right direction component of the display device 4, respectively. Outputs S2.

The detection signals S1 and S2 are integrated by the operational amplifier circuits 10 and 11, respectively, whereby detection signals SD1 and SD2 whose signal levels change according to the magnitude and direction of the combined magnetic field are obtained. The detection signal SD1
And SD2 are voltage-current converted by the operational amplifier circuits 28 and 30, and then the Helmholtz coils 33, 34, 43, and 4.
A magnetic field is formed by the Helmholtz coils 33, 34, 43, 44 so that the combined magnetic field Φ2 is 0.

(3) Effects of the Embodiments According to the above configuration, the external magnetic field can be maintained in a canceled state by forming a magnetic field so as to cancel the geomagnetism by the Helmholtz coil based on the detection result of the geomagnetic sensor. Thus, with a simple structure, mislanding and screen distortion of the cathode ray tube can be avoided.

(4) Other Embodiments In the above-mentioned embodiments, the case of canceling the earth magnetism by applying it to the display device using the color cathode ray tube has been described. However, the present invention is not limited to the color cathode ray tube and the black and white. It may be applied to a display device using a cathode ray tube for display. By doing so, screen distortion due to an external magnetic field can be effectively avoided.

Further, in the above-mentioned embodiment, the case where the external magnetic field is canceled with respect to the horizontal component force is described, but the present invention is not limited to this, and the vertical component force may be canceled.

That is, when the display device is used only in a predetermined area such as in Japan, the mislanding and the like can be practically sufficiently prevented only by canceling the horizontal component of the earth's magnetism. However, when used in areas with different latitudes, vertical force must be corrected in addition to horizontal force. In this case, as shown in FIG. 7, the geomagnetic sensor 2Z is arranged so as to detect the vertical component force, and the Helmholtz coils 50 and 51 are arranged so as to cancel the component force in the vertical direction.
By arranging, the vertical component force can be corrected.

[0037]

As described above, according to the present invention, a magnetic field forming current is applied to the Helmholtz coil so as to cancel the external magnetic fields in the first and second directions based on the first and second magnetic field detection results. By supplying it, it is possible to obtain a landing correction device that can reliably avoid the influence of the external magnetic field with a simple configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing a landing correction device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing an arrangement of a geomagnetic sensor.

FIG. 3 is a plan view for explaining the operation of the geomagnetic sensor.

FIG. 4 is a signal waveform diagram showing an output signal of the geomagnetic sensor.

FIG. 5 is a schematic diagram for explaining the correction in the x direction.

FIG. 6 is a schematic diagram for explaining the correction in the y direction.

FIG. 7 is a schematic diagram for explaining another embodiment.

[Explanation of symbols]

1 ... Landing correction device, 2X, 2Y, 2Z ... Geomagnetic sensor, 4 ... Display device, 10, 11, 28, 30
... Amplification circuit 33, 34, 43, 44, 50, 5
1 ... Helmholtz coil.

[Procedure amendment]

[Submission date] February 25, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction content]

On the other hand, when correcting the external magnetic field,
Landing correction coil (LCC: landing)
The correc tion coil) disposed in a predetermined position, supplying a current corresponding to the correction amount to the Randeingu correction coil. As a result, in this type of display device, mislanding and screen distortion due to the influence of geomagnetism and the like can be effectively avoided.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0009

[Correction method] Change

[Correction content]

[0009]

In order to solve the above problems, according to the present invention, Helmholtz coils 33, 34 and 43 for forming a magnetic field across a cathode ray tube in first and second orthogonal directions x and y. , 44 and the Helmholtz coils 33, 34, 43, 44, and the magnetic sensor 2 that outputs magnetic field detection results S1 and S2 in the first and second directions x and y, respectively, and the magnetic field detection result. Based on S1 and S2, the magnetic field correction circuits 8 to 47 for supplying the magnetic field forming current I to the Helmholtz coils 33, 34, 43 and 44 so as to cancel the external magnetic field Φ2 in the first and second directions x and y. And prepare for.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

(1) Configuration of the Embodiment In FIG. 1, reference numeral 1 denotes the landing correction device as a whole, and the geomagnetic sensor 2 detects the combined magnetic field of the geomagnetism and the correction magnetic field in the x and y directions, and based on the detection result. Generate a correction magnetic field.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

Here, the geomagnetic sensor 2 includes a driving winding 2D driven by a high frequency power source 6 on a ring-shaped core 2C .
And the detection windings 2X and 2Y in addition to this , the driving winding 2D forms a magnetic flux Φ1 that surrounds the ring-shaped core 2C as shown in FIG. Is wound like. On the other hand, the magnetic flux φ2 due to geomagnetism is
Proceed in the same direction in the ring-shaped core 2C.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction content]

As a result, the magnetic flux φ1 generated by the drive winding and the ground
The sum of the magnetic flux with the magnetic flux φ2 is the detection winding 2X or
Although detected by 2Y, the magnetic flux φ1 is the same at points A and B.
Since it is in the opposite direction, it is canceled out, and only the magnetic flux φ2 due to the geomagnetism
Will be detected.

[Procedure Amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

Here, the geomagnetic sensor 2 includes the detection winding 2 X
The direction orthogonal to is the front-back direction of the display device 4 (represented by the symbol x), and is also orthogonal to the detection winding 2Y.
The display device 4 is arranged so as to be in the left-right direction (represented by the symbol y) at a substantially central position of the display device 4 while avoiding the cathode ray tube.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

Further, the geomagnetic sensor 2 has a detection winding 2X.
And detection outputs e1 and e2 from 2Y are detected by a detection circuit (DE
T) Output to 2M and 2N, where a voltage level sufficient for practical use is obtained.
The detection outputs e1 and e2 are detected so that the bell becomes
The detection outputs S1 and S2 are output.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

In the landing correction device 1, the detection signal S1 is applied to the inverting input terminal of the operational amplifier circuit 10 via the resistor 8 and the detection signal S1 is applied to the inverting input terminal of the operational amplifier circuit 11 via the resistor 9. Operational amplifier circuits 10 and 11
Is a resistor 12, a variable resistor 14, and
The offset voltage formed by the resistors 16 and 18, the variable resistor 20, and the resistor 22 is input, and the output terminal
Connect capacitors 24 and 25 for oscillation prevention to the inverting input terminal
It is designed to continue .

[Procedure Amendment 9]

[Document name to be amended] Statement

[Name of item to be corrected] 0019

[Correction method] Change

[Correction content]

As a result, the operational amplifier circuits 10 and 11 are
The detection signals S1 and S2 are amplified with an almost infinite gain, and the detection signals SD1 and SD2 are output .

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

Here, in the geomagnetism, it can be decomposed into a vertical component force and a horizontal component force, and the horizontal component force extends north and south at a predetermined declination angle. Therefore, the geomagnetic sensor 2
When arranging, the magnitude of the external magnetic field Φ2 interlinking with the geomagnetic sensor 2 changes according to the orientation of the display device 4.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Name of item to be corrected] 0025

[Correction method] Change

[Correction content]

At this time, as shown in FIG. 5, the Helmholtz coils 33 and 34 are arranged in front of and behind the display device 4 and driven by the output signal of the operational amplifier circuit 28 for detection.
The correction magnetic field is formed so as to cancel the external magnetic field detected by the winding 2X. On the other hand, FIG.
The Helmholtz coils 43 and 44 are arranged on the left and right of the display device 4 as shown in FIG. 4 and are driven by the output signal of the operational amplifier circuit 30 to cancel the external magnetic field detected by the detection winding 2Y. Are designed to form.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0026

[Correction method] Change

[Correction content]

As a result, in the landing correction device 1, the Helmholtz coils 33, 34, 43, 4 are arranged so that the magnetic flux Φ2 detected by the geomagnetic sensor 2 becomes zero.
4 is driven.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

(2) Operation of the embodiment With the above configuration, the Helmholtz coils 33, 34,
43 and 44 are driven by the operational amplifier circuits 28 and 30 to form a magnetic field determined by the current I and the number of windings n, whereby the Helmholtz coil 3 is provided inside the display device 4.
The combined magnetic field Φ 3 of the correction magnetic field and the geomagnetism formed by 3, 34, 43, and 44 is formed. Geomagnetic sensor 2 here
Is driven by the high-frequency power source 6 to detect detection signals S1 and S2 whose amplitudes change with respect to the combined magnetic field Φ 3 in accordance with the sizes and directions of the front-rear direction component and the left-right direction component of the display device 4, respectively. Output.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Name of item to be corrected] 0032

[Correction method] Change

[Correction content]

The detection signals S1 and S2 are amplified by the operational amplifier circuits 10 and 11, respectively, with an almost infinite gain , whereby the signal level changes according to the magnitude and direction of the combined magnetic field. Detection signals SD1 and SD2 are obtained. The detection signals SD1 and SD2 are supplied to the operational amplifier circuit 2
After voltage-current conversion in 8 and 30, the Helmholtz coil 3 is output so that it is output to the Helmholtz coils 33, 34, 43, 44, so that the combined magnetic field Φ 3 becomes 0.
A magnetic field is formed at 3, 34, 43 and 44.

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Explanation of symbols] 1 ... Landing correction device, 2 ... Geomagnetic sensor, 4
... Display device, 10, 11, 28, 30 ... Operational amplifier circuit, 33, 34, 43, 44, 50, 51 ... Helmholtz coil.

[Procedure 16]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 17]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 2

[Correction method] Change

[Correction content]

[Fig. 2]

[Procedure 18]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

[Procedure Amendment 19]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

[Procedure amendment 20]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 7

[Correction method] Change

[Correction content]

[Figure 7]

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H04N 9/29 A 9187-5C

Claims (1)

[Claims] 1. A Helmholtz coil for forming a magnetic field across a cathode ray tube in first and second directions which are orthogonal to each other, and a Helmholtz coil arranged so as to be surrounded by the Helmholtz coil, respectively in the first and second directions. A magnetic sensor that outputs a magnetic field detection result and a magnetic field correction circuit that supplies a magnetic field forming current to the Helmholtz coil so as to cancel the external magnetic fields in the first and second directions based on the magnetic field detection result. A landing correction device characterized by being provided.