JP2000013812A - Receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct landing in an excellent way by avoiding the detected magnetic field of geomagnetic sensor from being weakened due to correction of rotation. SOLUTION: The neck part of a cathode ray tube 1 is provided with a rotation correction coil 2. The solid arrows in the figure indicate the geomagnetism and the dotted arrows show the magnetic field generated by the rotation correction coil 2. The solid arrows and the dotted arrows are directed in the same direction on the outside of the area surrounded by the single dashed chain line where the magnetic field is strengthened. Accordingly a geomagnetism sensor 3 that senses the magnitude of geomagnetism is provided, e.g. at a position directly beneath the rotation correction coil 2 shown by an arrow directed in both directions, on the outside of the area surrounded by the single dashed chain line. Furthermore, the direction of the arrow 3 in the figure also indicates the direction of the magnetic field sensed by the geomagnetism sensor 3. Thus, the magnetic field sensed by the earth magnetism sensor 3 is not weakened by the rotation correction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a receiver suitable for use in correcting, for example, image rotation of a cathode ray tube and correcting a landing error due to the influence of terrestrial magnetism. Specifically, the sensor is installed so that the detection of terrestrial magnetism is not impaired by a magnetic field generated by a correction coil that corrects image rotation.

[0002]

2. Description of the Related Art The earth is magnetized in the course of its birth, forming a large magnet. Therefore, on the earth, magnetic flux passes from the southern hemisphere to the northern hemisphere as shown in FIG.
This magnetic flux is called geomagnetism, and its direction and intensity vary depending on longitude and latitude. This geomagnetism is considered to be divided into two, a vertical magnetic field and a horizontal magnetic field, as shown in FIG. As is evident from FIG. 3, the horizontal magnetic field is always northward, and the vertical magnetic field is downward in the northern hemisphere and upward in the southern hemisphere.

Here, the horizontal magnetic field always travels from north to south, but in the following description, as shown in FIG. 4, the north-south direction refers to the direction perpendicular to the cathode ray tube, and the east-west direction refers to the east-west direction. Means a magnetic field in a lateral direction when viewed from the image receiving surface of the cathode ray tube. Note that the vertical magnetic field is downward in the Northern Hemisphere as shown, and is upward in the Southern Hemisphere.

[0004] Incidentally, the cathode ray tube develops a color by irradiating a phosphor with electrons. There is a flow of electrons (current). This current is affected by the geomagnetism from Fleming's law as shown in FIG. 5, for example, and the orbit is bent. This is the mechanism of mislanding due to geomagnetism. FIG. 6 shows a change in the landing pattern depending on the installation direction of the cathode ray tube.

That is, FIG. 6 shows how the landing changes when the cathode ray tube faces in that direction. In FIG. 6, a square frame indicates a display surface of the cathode ray tube, a dotted line indicates a landing pattern when no magnetic field is applied, and a solid line indicates a change in the landing pattern when terrestrial magnetism is applied. In FIG. 6, all green signals are considered. This is because, in general, in the case of an electron gun arranged in a straight line, since the center is green, it is easy to consider a change.

Accordingly, in FIG. 6, when the solid line is on the left side of the dotted line, it indicates that the green beam is shifted to, for example, the red side, and when it is on the right side, the green beam is shifted, for example, to the blue side. To indicate that Also, the steeper the angle, the greater the amount of displacement.

[0007] For example, when the cathode ray tube is facing northwest, the maximum shift occurs at the upper left point on the red side,
At the lower left point, the largest shift occurs on the blue side. This is because the northwest landing pattern is a combination of the north landing pattern and the west landing pattern. In contrast, the landing does not change on the right. This is because when the north landing pattern and the west landing pattern are combined on the right side, the changes cancel each other out and disappear.

[0008]

In view of the influence of geomagnetism on such a landing pattern, the applicant of the present invention has previously installed a correction coil, for example, around the image receiving surface of a cathode ray tube. A means (system) for compensating for the influence of terrestrial magnetism by passing a predetermined DC current through the horn has been proposed (see Japanese Patent Application No. 10-99303).

In this terrestrial magnetism correction system, for example, correction is performed using a terrestrial magnetism sensor 10 described later, for example, as shown in FIG. Here, for example, a horizontal magnetic field in the north-south direction is detected (output X-out) from the geomagnetic sensor 10. Also, the stabilized voltage V from this geomagnetic sensor 10
reg. and the reference voltage Vref. are supplied to the control circuit 11 to control the reference voltage Vref.

A mute circuit 12 is provided between the reference voltage Vref. And the detection output X-out. The mute circuit 12 is controlled by, for example, a mute signal from a control microcomputer 13 and wants to stop the generation of a magnetic field, for example, during demagnetization of a cathode ray tube at power-on or during an adjustment process in a production line. Sometimes muting is performed.

The reference voltage Vref. And the detection output X-out from the geomagnetic sensor 10 are supplied to the differential amplifiers 14 and 15 mutually. Therefore, these differential amplifiers 1
A direct current corresponding to the strength of the horizontal magnetic field flows between the outputs 4 and 15. This DC current is supplied to a landing correction coil 16 provided around the image receiving surface of the cathode ray tube, for example, and a magnetic field opposite to the horizontal magnetic field is formed to perform correction.

FIG. 8 shows a specific configuration in a case where the landing correction coil 16 is provided around the image receiving surface of the cathode ray tube. That is, FIG. 8A shows a perspective view of the appearance of the receiver, and FIG. 8B shows a cross-sectional view of the main part. In these figures, a so-called beznet 102 is provided around an image receiving surface 101 of the cathode-ray tube 100. The cathode-ray tube 10 is provided inside the beznet 102, for example, at a position indicated by a circle.
The landing correction coil 16 is provided so as to surround the zero image receiving surface 101.

When a current flows through the landing correction coil 16, the landing correction coil 16 moves in a direction perpendicular to the image receiving surface of the cathode ray tube (north-south direction) as shown in FIG. A magnetic field is formed, and the influence of the terrestrial magnetism is canceled by the magnetic field, and landing correction is performed. In the above-mentioned prior application, the correction in the east-west direction is also performed. However, since it is not directly related to the present application, only the north-south direction is described here.

In the above-mentioned apparatus, the configuration of the geomagnetic sensor 10 is, for example, as shown in FIG. In FIG. 10, an oscillation signal from an oscillator 21 is supplied to a detection coil 22 serving as a sensor body. Then, the signal from the detection coil 22 is supplied to the peak detection circuit 23 and is detected by the oscillation signal from the oscillator 21. The signal from the detection circuit 23 is supplied to the amplifiers 24 and 25, and is taken out as the above-mentioned detection output X-out.

Further, the power supply Vcc is supplied to the stabilizing circuit 26, and the stabilized voltage Vreg. The stabilizing voltage Vreg. Is supplied to the reference voltage Vref. Forming circuit 27, and the formed reference voltage Vref.
The reference voltage Vref. Is supplied to the amplifiers 24 and 25, and the detection output X-out is output based on the reference voltage Vref.

In this circuit, the detection coil 22
, An output voltage [V] that is changed linearly with respect to the magnitude [μT] of the terrestrial magnetism as shown in FIG. Further, when the detection coil 22 is rotated by 360 °, an output voltage [V] that draws, for example, a sine curve as shown in FIG. B in FIG. 11 is a horizontal magnetic field Bh.
= 40 [μT], and the reference voltage Vref. Is a voltage when the horizontal magnetic field in the north-south direction is “0”.

FIG. 12 shows the amplifiers 14 and 15 described above.
FIG. 3 specifically shows a main part of an example of a driving circuit of the landing correction coil 16 including the following. In FIG. 12, a reference voltage Vref. (Indicated by a voltage source 30) is connected to the non-inverting input (+) of each of the amplifiers 14 and 15 via resistors 31 and 32, respectively. Also, the detection output X-out
Is connected to respective inverting inputs (−) of the amplifiers 14 and 15 via resistors 34 and 35, respectively.

Further, resistors 36 and 37 are connected between the inverted input (−) and the output of each of the amplifiers 14 and 15. The outputs of these amplifiers 14 and 15 are passed through resistors 38 and 39, respectively.
Are connected to both ends. Note that the resistor 40 and the capacitor 4
Numeral 1 is provided for preventing oscillation of the landing correction coil 16.

Therefore, in this circuit, the gain of the amplifier 14 is determined by the ratio of the resistance values of the resistors 34 and 36, and the gain of the amplifier 15 is determined by the ratio of the resistance values of the resistors 35 and 37. The output voltages E1,
A correction current flowing through the landing correction coil 16 is formed by the difference of E2.

That is, in this circuit, when the above detection output X-out rises, the output voltage E of the amplifiers 14 and 15 becomes higher.
1 and E2 both rise, but here the amplifier 14,
By setting the gain of 15, the slopes of the output voltages E1 and E2 can be changed, for example, as shown in FIG. As a result, a potential difference is formed between the output voltages E1 and E2, and this potential difference (E1
By -E2), a correction current corresponding to the detection output X-out is passed through the landing correction coil 16.

As a result, the landing correction coil 16
, A correction current flows in either the positive or negative direction according to the detection output X-out. Since the current value of the landing correction coil 16 required for the correction differs depending on the individual device of the receiver, the gain of the amplifiers 14 and 15 is set at, for example, the resistors 34/36 and 35/37 at the final stage of product manufacture. Is determined by adjusting the resistance value or the like. In this manner, the landing error for the cathode ray tube is corrected using the sensor 10 that detects the magnitude of the geomagnetism.

On the other hand, in such an apparatus, when a change occurs in the magnetic field in the tube axis direction with respect to the image receiving surface of the cathode ray tube, a force of a rotational component with respect to the center of the scanning surface is applied to the electron beam. Therefore, rotation of the display image occurs. For such image rotation (rotation),
To correct this, the present applicant has previously proposed the following apparatus (see Japanese Patent Application No. 9-39307).

That is, in FIG. 14, for example, a correction value of the image rotation set by the user is supplied to the control microcomputer 52 through the input means 51. The PWM signal generated by the microcomputer 52 is supplied to the amplifiers 54 and 55 through the low-pass filter 53. The outputs of the amplifiers 54 and 55 are supplied to both ends of the rotation correction coil 56.

The amplifiers 54 and 55 have a difference in gain similarly to the amplifiers 14 and 15 described above. Then, due to the gain difference between the amplifiers 54 and 55, a correction current corresponding to the correction value set in the input means 51 flows through the rotation correction coil 56.

Further, the above-described rotation correction coil 5
Reference numeral 6 is provided at the neck of the cathode ray tube 100, for example, as shown in FIG. When a correction current flows through the rotation correction coil 56, a magnetic field is formed as shown by a solid line in the figure, thereby canceling out the influence of terrestrial magnetism and correcting the image rotation.

However, in these devices, when image rotation correction is performed using, for example, the rotation correction coil 56, a magnetic field in a direction opposite to the terrestrial magnetism is generated at the center of deflection to cancel the terrestrial magnetism. Therefore, depending on the position from the rotation correction coil 56, there is an area where the magnetic field becomes weaker than before the image rotation correction is performed.

If, for example, the geomagnetic sensor 10 is installed in such an area, the geomagnetic sensor 10 will detect a weaker magnetic field when the user performs rotation correction. In that case, for example, there has been a problem that the correction amount of the landing correction becomes weaker accordingly.

As a measure against this problem, for example, the gain of the correction amount detected by the terrestrial magnetism sensor 10 is increased in advance so that the correction amount of the landing correction becomes appropriate when the image rotation correction is performed. There is a means to do this. However, for example, when the rotation correction and the landing correction exist independently as described above, it is unknown whether or not the user is performing the image rotation correction.
Such a measure could not be taken.

The present application has been made in view of such a point, and the problem to be solved is that in the conventional apparatus, for example, when rotation correction and landing correction exist independently, , A geomagnetic sensor detects a magnetic field weakened by, for example, rotation correction,
For example, there is a problem that the correction amount of the landing correction becomes weaker accordingly.

[0030]

Therefore, in the present invention, the magnitude of the terrestrial magnetism is set in an area in which the direction of the magnetic field generated by the correction coil and the direction of the component of the terrestrial magnetism in the direction perpendicular to the image receiving surface of the cathode ray tube are the same. In this configuration, the detection magnetic field is not weakened by the rotation correction, and a good landing correction can always be performed.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a receiver having a cathode ray tube, comprising means for correcting the image rotation of the cathode ray tube using a correction coil, and a cathode ray tube using a sensor for detecting the magnitude of terrestrial magnetism. When the means for correcting the landing error with respect to the tube is provided independently, the area in which the direction of the magnetic field generated by the correction coil and the direction of the vertical component with respect to the image receiving surface of the terrestrial magnetism cathode ray tube are the same. And a sensor for detecting the magnitude of geomagnetism.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a main part of an example of a receiver to which the present invention is applied.

That is, in FIG. 1, a rotation correction coil 2 is provided at the neck of the cathode ray tube 1.
Further, in FIG. 1, solid-line arrows indicate terrestrial magnetism, and dotted-line arrows indicate magnetic fields generated by the rotation correction coil 2. Although the magnetic field indicated by the dotted line is originally shown in FIG.
3 shows only the component perpendicular to the image receiving surface of the cathode ray tube 1 in FIG.

In FIG. 1, in the area surrounded by the dashed line, the solid arrow indicating the terrestrial magnetism and the dotted arrow indicating the magnetic field generated by the rotation correction coil 2 are in opposite directions. In this area, the magnetic fields cancel each other out and the magnetic field is weakened. On the other hand, outside the area surrounded by the dashed line, the solid arrow and the dotted arrow point in the same direction, and the magnetic field is strengthened in this area.

In FIG. 1, a geomagnetic sensor 3 for detecting the magnitude of the above-mentioned geomagnetism is provided outside the area surrounded by the dashed line, for example, at a position indicated by an arrow.
Is provided. The arrows in the figure also indicate the direction of the magnetic field detected by the geomagnetic sensor 3.

That is, in this device, the geomagnetic sensor 3 is provided directly below the rotation correction coil 2. Therefore, the magnetic field detected by the geomagnetic sensor 3 is also affected by the magnetic field generated by the rotation correction coil 2. Here, the magnetic field generated by the rotation correction coil 2 acts in a direction to cancel the geomagnetism inside the area surrounded by the dashed line in the coil.

However, since the magnetic field generated by the rotation correction coil 2 is in the same direction as the terrestrial magnetism outside the area surrounded by the one-dot chain line just below the coil, the magnetic field generated by the rotation correction coil 2 emphasizes the terrestrial magnetism in this case. Will work in the direction that you do. Therefore, by setting the magnetic field detected when the rotation correction coil 2 is operated as the emphasized geomagnetism and setting the maximum correction amount at that time, the geomagnetism sensor 3 can easily detect the geomagnetism. Can be.

Further, the rotation correction coil 2
Is arbitrarily operated by, for example, the input means 51 in FIG. Then, for example, a horizontal magnetic field Bh = 40 [μ
T], the correction value when the direction of the cathode ray tube 1 faces south is, for example, -4, and the correction value when the direction of the cathode ray tube 1 is north is, for example, +4.
And Further, it is set to -2 in the south intermediate direction and +2 in the north intermediate direction.

As described above, in this apparatus, the terrestrial magnetism which is originally hard to be detected is reduced by the rotation correction coil 2.
It can also be said that the detection is made easier by emphasizing the magnetic field generated in step (1). Note that the above-described correction value of −
The numbers of 4, +4, -2, and +2 are rough guidelines and are arbitrarily determined in the design of the device. In this case, for example, in the apparatus used in the experiment, the -4 and +4 correction values emphasize the geomagnetism by about 22%, and the -2 and +2 correction values emphasize the terrestrial magnetism by about 17%.

Therefore, in this apparatus, a sensor for detecting the magnitude of the terrestrial magnetism is installed in an area in which the direction of the magnetic field generated by the correction coil is the same as the direction of the component of the terrestrial magnetism in the direction perpendicular to the image receiving surface of the cathode ray tube. Thus, the magnetic field detected by the terrestrial magnetism sensor is not weakened by the rotation correction, and good landing correction can always be performed.

Thus, in the conventional apparatus, for example, when the rotation correction and the landing correction exist independently, the geomagnetic sensor detects the magnetic field weakened by, for example, the rotation correction, and the correction amount of the landing correction is reduced. According to the present invention, these problems can be easily solved, although there have been problems such as weakening accordingly.

In the above-described apparatus, the position where the geomagnetic sensor is attached is not limited to the position directly below the rotation correction coil 2 but may be outside the area enclosed by the dashed line. May be inside the lower end corner of the cabinet of the receiver as shown by arrow a.

Thus, according to the above-mentioned receiver of the present invention,
A means having a cathode ray tube, wherein means for correcting the image rotation of the cathode ray tube using a correction coil and means for correcting a landing error with respect to the cathode ray tube using a sensor for detecting the magnitude of terrestrial magnetism are independently provided. If provided, install a sensor that detects the magnitude of terrestrial magnetism in an area where the direction of the magnetic field generated by the correction coil is the same as the direction of the component of the terrestrial magnetism perpendicular to the image receiving surface of the cathode ray tube. Thus, the detection magnetic field of the geomagnetic sensor is not weakened by the rotation correction, and a good landing correction can always be performed.

It should be noted that 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.

[0045]

According to the first aspect of the present invention, the magnitude of the terrestrial magnetism is set in an area where the direction of the magnetic field generated by the correction coil is the same as the direction of the component of the terrestrial magnetism in the direction perpendicular to the image receiving surface of the cathode ray tube. By installing a sensor for detecting the magnetic field, the detected magnetic field of the geomagnetic sensor is not weakened by the rotation correction, and a good landing correction can always be performed.

Thus, in the conventional apparatus, for example, when the rotation correction and the landing correction exist independently, the geomagnetic sensor detects the magnetic field weakened by, for example, the rotation correction, and the correction amount of the landing correction, for example, is reduced. According to the present invention, these problems can be easily solved, although there have been problems such as weakening accordingly.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a main part of an example of a receiver to which the present invention is applied.

FIG. 2 is a diagram showing installation positions of sensors of another example of the image receiver to which the present invention is applied.

FIG. 3 is a diagram for explaining geomagnetism.

FIG. 4 is a diagram for explaining a relationship between a receiver and terrestrial magnetism.

FIG. 5 is a diagram for explaining Fleming's law.

FIG. 6 is a diagram showing a change in landing.

FIG. 7 is a configuration diagram of a geomagnetic correction system.

FIG. 8 is a diagram for explaining installation of a landing correction coil.

FIG. 9 is a diagram for explaining a magnetic field generated by a landing correction coil.

FIG. 10 is a configuration diagram of a geomagnetic sensor.

FIG. 11 is a characteristic diagram of the detection signal.

FIG. 12 is a configuration diagram of a driving circuit of a landing correction coil.

FIG. 13 is a characteristic diagram of the output signal (voltage).

FIG. 14 is a configuration diagram of an image rotation (rotation) correction device.

FIG. 15 is a configuration diagram showing an arrangement of a rotation correction coil and a magnetic field generated by the coil.

[Explanation of symbols]

1 ... cathode ray tube, 2 ... rotation correction coil, 3 ... geomagnetic sensor

Claims (2)

[Claims] 1. A receiver having a cathode ray tube, comprising: means for correcting image rotation of the cathode ray tube using a correction coil; and a landing error with respect to the cathode ray tube using a sensor for detecting the magnitude of terrestrial magnetism. In the case where the means for performing the correction is provided independently, the direction of the magnetic field generated by the correction coil and the direction of the vertical component of the terrestrial magnetism with respect to the image receiving surface of the cathode ray tube have the same direction, A receiver characterized by installing a sensor for detecting the magnitude of geomagnetism. 2. The receiver according to claim 1, wherein a landing error caused by the influence of the terrestrial magnetism on the cathode ray tube is determined based on a time when image rotation of the cathode ray tube is corrected using the correction coil. A receiver, wherein each of the means is set to a characteristic in which correction is optimal.