JPS584871B2 - color television station - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic landing correction device for a color television receiver that automatically corrects mislanding caused by the earth's magnetism in the color television receiver.

In general, color cathode ray tubes in color television receivers use three electron beams (hereinafter referred to as R beams, G beams, and B beams) that stimulate phosphors that emit light in the three primary colors of red, green, and blue in response to signals sent from broadcasting stations. The luminance of the three colors is adjusted by modulating the current value of the three colors, thereby reproducing any color contained within the triangle formed by these three colors on the chromaticity diagram.

However, due to the influence of the earth's magnetic field, the electron beams are bent depending on the installation location of the color television receiver and the orientation of the screen of the color cathode ray tube, causing the electron beams to be slightly away from a predetermined position on the phosphor screen, resulting in mislanding.

That is, FIG. 1 shows the state of mislanding in Tokyo, and as shown in FIG. 1, different mislandings occur depending on the orientation of the screen of the television receiver.

The broken line in FIG. 1 indicates the area where the electron beam hits due to the action of the horizontal force of the earth's magnetism, and the difference between the solid line (when the electron beam hits correctly) and this broken line is the amount of mislanding.

As is clear from Fig. 1, there is a certain regularity to this mislanding due to the earth's magnetic field, and the color cathode ray tube is trapezoidal in the east and west directions, and parallelogram in the south and north directions. Moreover, the positions of the northeast, southeast, northwest, and southwest directions form a composite shape of the shapes of these east and west directions and the south and north directions.

In view of this, the present invention proposes an automatic landing correction device for a color television receiver, which automatically corrects mislanding due to the influence of earth's magnetic field.

Hereinafter, an embodiment of the automatic landing correction device for a color television receiver according to the present invention will be described with reference to FIG.

In FIG. 2, 1 is a first magnetic field detection means for detecting a magnetic field in the tube axis direction of a color cathode ray tube, and 2 is a first magnetic field detection means for detecting a magnetic field in a direction perpendicular to the tube axis direction of this color cathode ray tube in a horizontal plane. This is a second magnetic field detection means for detecting.

These first and second magnetic field detection means 1 and 2 are arranged in association with a color cathode ray tube of a color television receiver.

For example, a sensor as shown in FIG. 3 is used as the first and second magnetic field detection means. In other words, this sensor is made of a magnetic material such as permalloy having a remarkable saturation BH characteristic as shown in FIG. 4A. A drive coil is formed by forming a square-shaped core K as shown in FIG. 3, and winding a detection coil 1c over the two legs 1a and 1b, and further winding each leg 1a and 1b in a predetermined direction. 1d, and when an external magnetic field is applied in the axial direction of the coil 1d, the magnetic flux density Ba and Bb in the legs 1a and 1b around which the drive coil 1d is wound become +BG and -BG, respectively. When a pulse current with a vertical period as shown in FIG. 4B is passed through the drive coil 1d, the magnetic flux density of the legs 1a and 1b increases as the current rises, and both legs 1a and 1b are saturated at the magnetic flux density Bs. Due to the characteristic that it is biased by +BG due to the external magnetic field HG, leg 1
a reaches saturation first (time t1).

Also, since the leg 1b is biased in the opposite direction to the leg 1a by the magnetic flux density BG, it reaches saturation at time t2, which is later than time t1 (see FIG. 4C).

Further, when the current flowing through the drive coil 1d falls, the operation opposite to that described above is performed.

Therefore, the composite magnetic flux (Ba-Bb
) S is 2BG・S when the drive current is not flowing (here, S is the cross-sectional area of each of legs 1a and 1b)
, this combined magnetic flux becomes 0 when both legs 1a and 1b reach saturation (see FIG. 4D).

Therefore, a pulse voltage of dφ/dt (φ is the magnetic flux inside the detection coil 1c) is generated in the detection coil 1c (Fig. 4E).
reference).

The detected pulse shown in Figure 4E is a signature of a pulse with a vertical period, so if you integrate it, you will get a vertical pulse (see Figure 4F), and if you integrate it again, you will get a sawtooth wave with a vertical period. A signal is obtained (see Figure 4G).

In this example, a sensor as shown in FIG. 3 is arranged to detect the magnetic field in the tube axis direction of the color cathode ray tube, and this is used as the first magnetic field detection means, and the other sensors are placed in the horizontal plane. The second magnetic field detection means is arranged so as to detect a magnetic field in a direction perpendicular to the tube axis direction of the color cathode ray tube.

In this example, the respective output signals of the magnetic field detection means 1 and 2 are supplied to vertically periodic sawtooth wave forming circuits 3 and 4, respectively.

Further, the output signals of these vertically periodic sawtooth wave forming circuits 3 and 4 are supplied to amplifiers 5 and 6, respectively.

7 is a horizontal output transformer, and the primary winding 7 of this transformer 7 is
A horizontally periodic negative pulse is supplied between both ends of a.

One end of the secondary winding 7b of this transformer is connected to the base of a switching NPN transistor 8 via a resistor 9, and the other end of this secondary winding 7b is connected to the emitter of this transistor 8.

The collector of this transistor 8 is connected to the cathode of a diode 10, and this collector is also connected to the cathode of a diode 11, and the connection point of the secondary winding 7b of the transformer 7 with the resistor 9 is connected to the anode of the diode 12. and this connection point is connected to the anode of diode 13, the anode of diode 10 is connected to the cathode of diode 12, and the anode of diode 11 is connected to the anode of diode 13.
A capacitor 14 is connected between the connection point of diodes 10 and 12 and the connection point of diodes 11 and 13.

Furthermore, the connection point between diodes 11 and 13 is grounded.

Further, the connection point between the diodes 10 and 12 is grounded through a series circuit including a capacitor 15 for blocking low frequency signals and a landing correction coil 16.

In this case, the landing correction coil 16 is wound around a core and attached to the neck of a color cathode ray tube of a color television receiver.

Figure 5 shows this installed state, where the CRT shows the color cathode ray as a whole, and the landing correction coil 1.
The core DLC wound with 6 is attached to the neck N of this cathode ray tube CRT.

Note that DY is a deflection device. The output side of the amplifier 6 is connected to the connection point of diodes 10 and 12 via a choke coil 17 for blocking horizontal frequency signals, and the output side of the amplifier 5 is connected to a coil 18 and a resistor that constitute a filter for blocking high frequency signals. It is connected to the connection point of the capacitor 15 and the landing correction coil 16 via 19 series circuits.

Since the present invention is configured as described above, for example, when the screen of the television receiver is facing south, the first magnetic field detection means 1 can output a detection output corresponding to this direction, and the sawtooth At the output of the wave forming circuit 3, a sawtooth wave voltage as shown in FIG. Ru.

On the other hand, no detection signal is obtained from the output of the second magnetic field detection means 2 which detects a magnetic field in a direction perpendicular to the tube axis direction in the horizontal plane.

Therefore, the current flowing through the landing correction coil 16 is
The current becomes as shown in Figure A, making it possible to correct mislanding due to the earth's magnetic field when the screen faces south.

In addition, when the screen faces north, a signal corresponding to this direction is obtained as the output of the first magnetic field detection means 1, and a sixth signal with a level and polarity corresponding to this detection signal is obtained on the output side of the sawtooth wave forming circuit 3. Although a sawtooth wave voltage as shown in FIG. It is possible to correct mislanding due to geomagnetic field when the flow is northward.

Next, when the screen is facing east, a detection signal corresponding to this direction is obtained at the output of the second magnetic field detection means 2, and a level corresponding to this detection output is obtained at the output of the sawtooth wave forming circuit 4. A sawtooth wave voltage is obtained as shown in FIG.

The sawtooth wave voltage obtained in the sawtooth wave forming circuit 4 is obtained at the output side of the amplifier 6, and at this time, the horizontal output transformer 7
Therefore, a negative pulse signal with a horizontal period is supplied to the base of transistor 8, transistor 8 is turned on in the latter half of the horizontal scan, and the current flows from diode 10 to transistor 8 to diode 13, as shown by curve ih in Figure 6C. Thus, the current in the landing correction coil 16 increases with time.

Next, when a negative pulse in the retrace period is supplied to the base of the transistor 8, the transistor 8 is turned off, and due to resonance between the landing correction coil 16 and the capacitor 14, the landing correction coil 16 is turned off as shown by the curve ir in FIG. 16
The direction of the current flowing through is reversed.

Then, in the latter half of the horizontal scan, the transistor 8 turns on and the current flowing through the landing correction coil 16 flows through the diode 1.
1 → transistor 8 → diode 12, and the negative current flowing through the landing correction coil 16 is shown by the curve ih in Figure 6.
' gradually increases to 0.

From the time when this current ih' becomes 0, the current flowing through the landing correction coil 16 gradually increases again in the second half of the horizontal scan, and the above operation is repeated to create a sawtooth wave current with a horizontal period. be.

In this case, even if the voltage obtained at the connection point between the diodes 10 and 12 is positive or negative, the operation as described above will be exactly the same, just by changing the operating diode.

The horizontal period sawtooth wave current obtained in this way is amplitude modulated by the vertical period sawtooth wave voltage obtained at the output side of the amplifier 6, and as shown in FIG. The desired current waveform is such that the amplitude of the wave current gradually decreases and becomes 0 at the center of the vertical period, and the phase of the sawtooth wave current of the horizontal period is reversed in the latter half of the vertical period, and the amplitude becomes 0 and gradually increases. can get.

By supplying the current obtained in this way as shown in FIG. 6A to the landing correction coil 16, mislanding caused by the earth's magnetic field when the color cathode ray tube screen faces east as shown in FIG. 1 can be corrected. be able to.

When the cathode ray tube is facing west, the second magnetic field detection means 2 outputs a signal corresponding to this direction, and the sawtooth wave forming circuit 4 outputs a signal with a level and polarity corresponding to this detected output. A sawtooth wave voltage as shown in FIG. 6B is obtained, and therefore, the landing correction coil 16 receives a sawtooth waveform as shown in FIG. This can correct mislanding caused by the earth's magnetic field when current flows and the screen of the color cathode ray tube faces west.

As described above, even when the screen of the cathode ray tube is oriented in each of the 360 degree directions, mislanding due to earth's magnetism can be corrected in the same manner as described above.

As described above, according to the present invention, there is an advantage that mislanding due to earth's magnetism can be automatically corrected.

It goes without saying that the magnetic field detection means is not limited to the above-mentioned embodiments, and other magnetic field detection means such as those using Hall elements or SMDs can be used.

Furthermore, it goes without saying that the present invention is not limited to the above-described embodiments, and can take various configurations without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a state in which mislanding occurs due to earth's magnetism, FIG. 2 is a block diagram showing an embodiment of the landing correction device for a color television receiver of the present invention, and FIG. FIG. 4 is a diagram showing an example of the configuration, FIG. 4 is a diagram for explaining FIG. 3, and FIGS. 5 and 6 are diagrams for explaining the present invention. Numerals 1 and 2 are magnetic field detection means, 3 and 4 are sawtooth wave forming circuits, 7 is a horizontal output transformer, 14 and 15 are capacitors, 16 is a landing correction coil, and 17 and 18 are coils, respectively.

Claims (1)

[Claims] 1. A first magnetic field detection means for detecting a magnetic field in the tube axis direction of a color cathode ray tube and a second magnetic field detection means for detecting a magnetic field in a direction orthogonal to the tube axis direction in a horizontal plane, and a first and second sawtooth wave signal having a vertical period and a polarity and a magnitude corresponding to the detection by the second magnetic field detection means, and a sawtooth wave signal having a horizontal period with the second sawtooth wave signal. A color television receiver characterized in that a signal obtained by modulating a wave signal and the first sawtooth wave signal are superimposed and supplied to a dynamic landing correction coil arranged at the neck portion of the color cathode ray tube. The machine's automatic landing correction device.