JPH0851637A - Cathode-ray tube - Google Patents

Abstract

PURPOSE:To simplify constitution and to lower a cost by supplying correction signals for correcting the landing of an electronic beam at the time of scanning to a coil for degaussing magnetic members inside and outside a tube body. CONSTITUTION:In order to degausse the magnetic members inside and outside the tube body, the changeover switch 21 of a switching device 7 is operated, input terminals 10 and 11 and output terminals 8 and 9 are connected and an AC current is made flow to the coil 5. Thus, a clamping alternating magnetic field is generated from the coil 5 and the magnetic member such as a color selection mechanism or the like for instance is degaussed. On the other hand, in order to correct the landing of the electronic beam, the changeover switch 21 of the switching device 7 is operated, the other input terminals 12 and 13 and the output terminals 8 and 9 are connected and the coil 5 is connected to a signal generator 17. Then, various signals are supplied from the signal generator 17 to the coil 5 corresponding to the state of the mislanding of the electronic beam and a magnetic field for cancelling the mislanding is generated from the coil 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube used in, for example, a color picture tube or a color display device.

[0002]

2. Description of the Related Art Generally, in this type of cathode ray tube, it is necessary to prevent mislanding of an electron beam due to the influence of geomagnetism. Therefore, conventionally, for example, the periphery of the panel of the cathode ray tube and the funnel is surrounded by a magnetic member (magnetic shield), and a degaussing coil (degauss coil) is provided in a part of this magnetic shield to attenuate the degauss coil. By passing an alternating current, the magnetic members inside and outside the cathode ray tube are demagnetized. Further, in order to reduce the weight of the cathode ray tube and improve the demagnetization efficiency, a tube type in which a magnetic shield, that is, an internal magnetic shield is provided inside the tube has been devised.

On the other hand, during operation of the cathode ray tube, it is necessary to minimize mislanding of the electron beam. Therefore, conventionally, a coil for landing correction is provided in the cathode ray tube and various currents are made to flow through this coil.

[0004]

However, in such a conventional cathode ray tube, since the degauss coil and the coil for landing correction are separately provided, the structure of the device becomes complicated and the cost is increased. There was a problem that caused. On the other hand, the above-mentioned degauss coil does not need to be operated after the cathode ray tube is once installed in a predetermined direction, not only during the operation of the cathode ray tube but also until the direction of the cathode ray tube is changed again.

The present invention has been made in view of the above problems of the prior art, and it is an object of the present invention to provide a cathode ray tube capable of simplifying the structure of the portions related to the degaussing coil and the landing correction coil. To aim.

[0006]

In the cathode ray tube according to the present invention, as shown in FIGS. 1 to 6, for example, as shown in FIGS. 1 to 6, a coil 5 for demagnetizing a magnetic member inside and outside the tube is provided with an electron beam for scanning. A correction signal for correcting landing is supplied.

In this case, it is possible to provide a signal generator 17 for generating a correction signal having an arbitrary waveform according to the landing state of the electron beam.

It is also possible to provide a switching means 7 for switching between the degaussing current and the correction signal and supplying them to the coil 5.

Further, it is possible to provide a control means 15 for supplying a current for degaussing to the coil 5 immediately after the power source of the apparatus is turned on and then controlling so as to supply a correction signal to the coil 5.

[0010]

In the cathode ray tube according to the present invention, the coil 5 for demagnetizing the magnetic member inside and outside the tube is configured to supply the correction signal for correcting the landing of the electron beam during scanning. Therefore, the trajectory of the electron beam is corrected by the magnetic field generated from the coil 5, and as a result, it is not necessary to separately provide a coil for landing correction.

In this case, if a signal generator 17 for generating a correction signal having an arbitrary waveform according to the landing state of the electron beam is provided, optimum landing correction can be performed for various mislandings on the screen. You can

Further, if the switching means 7 for switching the degaussing current and the correction signal and supplying the coil 5 is provided, the demagnetization of the magnetic member or the landing correction of the electron beam can be carried out as required.

Further, if a control means 15 is provided for supplying a degaussing current to the coil 5 immediately after the power source of the apparatus is turned on and then supplying a correction signal to the coil 5, the control means 15 can be provided. During use, demagnetization of the magnetic member and landing correction of the electron beam are always performed.

[0014]

Embodiments of the cathode ray tube according to the present invention will be described below with reference to FIGS.

FIG. 2 is an external side view showing a schematic overall structure of the cathode ray tube 1 according to this embodiment. As shown in FIG.
The panel 2 and the funnel 3 constitute a tube body 4 of the cathode ray tube 1, and coils 5 for degaussing and landing correction are attached above and below this tube body. In the case of the cathode ray tube 1 of this embodiment, a part of each coil 5 is placed on the explosion-proof band 6 wound near the joint between the panel 2 and the funnel 3, and the coil 5 faces the funnel 3. Each coil 5 is configured to extend. Then, for example, an internal magnetic shield (not shown) is provided inside the tube body 4, but the others have a known configuration.

FIG. 1 is a circuit diagram showing the configuration of the main part of this embodiment. As shown in FIG. 1, in the present embodiment, the above-mentioned coil 5 is connected to the output terminals 8 and 9 of the switch 7 as the switching means. This switching device 7 has two types of input terminals 1
It has 0, 11 or 12, 13. The switch 7 is
Control circuit 15 as control means connected to timer 14
Connected to. The switch 7 is configured such that the connection between the input terminals 10, 11 or 12, 13 and the output terminals 8, 9 is switched by the changeover switch 21 that operates based on the control signal from the control circuit 15. The coil 5
Is connected in parallel with the capacitor 16.

One of the input terminals 10 and 11 of the switch 7 is
It is connected to the output of the signal generator 17. The signal generator 17 has a function of generating a sawtooth wave, a parabolic wave, or a pulse signal having an arbitrary waveform as well as a direct current.

The other input terminals 12 and 13 of the switch 7 are
It is connected to the AC power supply 20 via the resistor 18 and the switch 19. The resistor 18 is for attenuating the current flowing through the coil 5 due to the increase in the resistance value accompanying the temperature rise.

Next, the operation of the cathode ray tube 1 of this embodiment will be described. First, in order to demagnetize the magnetic member in order to avoid the influence of the earth magnetism, the changeover switch 21 of the changeover device 7 is operated to operate one of the input terminals 10 and 11 and the output terminals 8 and 9.
And are connected so that an alternating current flows through the coil 5. As a result, a damping alternating magnetic field is generated from the coil 5, and the magnetic member such as a color selection mechanism (not shown) is demagnetized. Note that this operation may be performed at the same time when the power switch of the cathode ray tube 1 is turned on.

On the other hand, in order to correct the landing of the electron beam, the changeover switch 21 of the changeover device 7 is operated to connect the other input terminals 12 and 13 and the output terminals 8 and 9, and the coil 5 is signaled. Connect to generator 17. And
As will be described later, various signals are supplied from the signal generator 17 to the coil 5 according to the mislanding state of the electron beam, and a magnetic field for canceling the mislanding is applied to the coil 5.
Generated from. The beam landing correction operation may be performed continuously after the degaussing operation described above is completed.

FIGS. 3 to 6 show the relationship between the mislanding state and the signal supplied from the signal generator 17 to the coil 5. First, as shown in FIG. 3A, for example, when uniform mislanding in the opposite direction (Y direction) occurs in the upper part and the lower part of the screen 22, as shown in FIG. A pulse signal 23 having a sawtooth waveform whose positive and negative polarities are reversed from the upper portion to the lower portion of 22 is supplied to the coil 5 in synchronization with the scanning of the electron beam.

Further, as shown in FIG. 4A, mislanding occurs in the upper part of the screen 22 in the direction from the center to both sides, and in the lower part of the screen 22 in the direction from both sides to the center. 4B, for example, as shown in FIG. 4B, the phases of the upper part and the lower part of the screen 22 are opposite to each other, and the screen 22
AC current 24 that attenuates toward the center of
It is supplied to the coil 5 in synchronization with the scanning of the electron beam.

Further, as shown in FIG. 5A, when mislanding occurs in one direction (Y direction) on the entire surface of the screen 22, as shown in FIG. Supply to.

Furthermore, as shown in FIG. 6A, screen 2
When mislanding in one direction (Y direction) occurs in the upper and lower end portions of No. 2, as shown in FIG. Coil 5 in synchronization with beam scanning
Supply to.

Then, by supplying these currents or signals to the coil 5, the landing correction of the electron beam is performed in the direction of canceling the mislanding on the screen 22.

In the cathode ray tube 1 of the present embodiment having such a configuration, a correction signal for correcting the landing of the electron beam during scanning is supplied to the coil 5 for demagnetizing the magnetic member inside and outside the tube. Since the coil is supplied, it is not necessary to separately provide a coil for landing correction, and the configuration can be simplified and the cost can be reduced.

Further, in the present embodiment, the signal generator 1
Since the correction signals of various waveforms are generated from 7 according to the state of landing of the electron beam, and the signals are supplied to the coil 5, the optimum landing correction for various mislandings on the screen is performed. It can be done so that an image without mislanding can always be obtained.

Further, since the degaussing current and the correction signal are switched by the switch 7 to be supplied to the coil 5, the demagnetization of the magnetic member or the landing correction of the electron beam can be performed as necessary. Demagnetization of the magnetic member and landing correction of the electron beam can be performed under optimum conditions.

In this case, a signal from the control circuit 15 connected to the timer 14 supplies a degaussing current to the coil 5 immediately after the power source of the apparatus is turned on, and then a correction signal is supplied to the coil 5. If it is controlled like this, the cathode ray tube 1
Since the demagnetization of the magnetic member and the landing correction of the electron beam are always performed during use, it is possible to maintain a high-quality image for a long period of time.

The present invention is not limited to the above-described embodiment, but various modifications can be made. For example, the signal supplied from the signal generator 17 to the coil 5 is not limited to the one described above, and various waveform signals can be supplied depending on the mislanding state.

Further, the timing for supplying the degaussing current to the coil 5 and the timing for operating the switch 7 are not limited to those in the above-described embodiment, but may be arbitrary. However, in order to maintain a high-quality image for a long period of time, it is most effective to control as in the above-mentioned embodiment.

Further, the present invention can be applied regardless of the shape (stripe or dot) of the beam transmission hole of the color selection mechanism, and can be applied regardless of the size and tube type of the cathode ray tube.

[0033]

As described above, according to the cathode ray tube of the present invention, the correction signal for correcting the landing of the electron beam during scanning is applied to the coil for demagnetizing the magnetic member inside and outside the tube. From the fact that
It is not necessary to separately provide a coil for landing correction, and as a result, the configuration can be simplified and the cost can be reduced.

In this case, if a signal generator for generating a correction signal having an arbitrary waveform according to the landing state of the electron beam is provided, optimum landing correction can be performed for various mislandings on the screen. Therefore, an image without mislanding can always be obtained.

Further, if a switching means for switching the degaussing current and the correction signal to the coil is provided, the demagnetization of the magnetic member or the landing correction of the electron beam can be carried out as necessary, which is optimum. Demagnetization of the magnetic member and landing correction of the electron beam can be performed under the conditions.

Further, if a control means is provided for supplying a degaussing current to the coil immediately after the power source of the apparatus is turned on, and then supplying a correction signal to the coil, a control means is provided to use the cathode ray tube. Since the demagnetization of the magnetic member and the landing correction of the electron beam are always performed, it becomes possible to maintain a high-quality image for a long time.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a main configuration of an embodiment of a cathode ray tube according to the present invention.

FIG. 2 is an external side view showing the schematic overall configuration of the embodiment.

FIG. 3 is an explanatory diagram (part 1) showing the relationship between the mislanding state and the signal supplied from the signal generator to the coil in the embodiment.

FIG. 4 is an explanatory diagram (part 2) showing the relationship between the mislanding state and the signal supplied from the signal generator to the coil in the embodiment.

FIG. 5 is an explanatory diagram (part 3) showing the relationship between the mislanding state and the signal supplied from the signal generator to the coil in the embodiment.

FIG. 6 is an explanatory diagram (part 4) showing the relationship between the mislanding state and the signal supplied from the signal generator to the coil in the embodiment.

[Explanation of symbols]

 1 Cathode ray tube 5 Coil 7 Switching device (switching means) 8,9 Output terminal 10, 11, 12, 13 Input terminal 14 Timer 15 Control circuit (controlling means) 17 Signal generator 20 AC power supply 22 Screen

Claims (4)

[Claims] 1. A cathode ray tube characterized in that a correction signal for correcting the landing of an electron beam during scanning is supplied to a coil for demagnetizing a magnetic member inside and outside the tube. 2. A cathode ray tube according to claim 1, further comprising a signal generator for generating a correction signal having an arbitrary waveform according to a landing state of the electron beam. 3. A cathode ray tube according to claim 1, further comprising switching means for switching between the degaussing current and the correction signal and supplying them to the coil. 4. A control means is provided which supplies a degaussing current to the coil immediately after the power source of the apparatus is turned on, and then controls so as to supply a correction signal to the coil. 2. The cathode ray tube according to any one of 2 and 3.