JPS5812976B2 - Denshibi Munohizumi Hosesouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam distortion correction device suitable for application to a cathode ray tube used in, for example, a color television receiver, and particularly to an electron beam distortion correction device that can reach a phosphor screen with a relatively simple configuration. This makes it possible to effectively correct the shape distortion of the electron beam.

In a cathode ray tube used in color television receivers, etc., the electron beam emitted from the cathode of the electron gun passes through a deflection magnetic field and finally reaches a desired point on the phosphor screen. Deflection is applied by the above-mentioned magnetic field to reach the target.

In this case, when observing the shape of the electron beam that has reached one point on the phosphor screen, the shape is distorted as shown in FIG. The amount of distortion tends to increase.

This tendency becomes more pronounced as the deflection angle of the electron beam becomes larger, that is, as the angle becomes wider.

As is well known, the cause of the distortion of the shape of the electron beam that reaches the periphery of the phosphor screen 1a is the magnetic field and convergence associated with dynamic focusing to correct the difference in focus between the center and periphery of the phosphor screen. This occurs due to an increase in the amount of deflection, as well as magnetic field distortion of the deflection yoke.

In order to correct such distortion of the electron beam, especially the distortion caused by the magnetic field distortion of the deflection yoke, a correction magnetic field based on a correction signal So as shown in Fig. 2 is applied to the electron beam before it is deflected. , deliberately distorting the shape of the electron beam.

That is, by creating a parabolic wave-like correction signal synchronized with the horizontal scanning period and supplying it to a correction coil placed on the cathode ray tube, the shape of the electron beam B, which has a regular shape (solid shape), is obtained as shown in Fig. 1B. In other words, it provides a correction magnetic field that extends in the vertical direction at its periphery as shown in FIG.

In this way, the shape of the electron beam when it finally reaches the phosphor screen 1a is corrected to a substantially normal shape due to the action of this correction magnetic field and the above-mentioned deflection magnetic field (see Figure 1C). , the intended purpose can be fully achieved.

By the way, in such a conventional device, a parapolar correction signal S having one horizontal scanning period as shown in FIG.
o, the necessary correction current cannot be easily obtained,
This has the disadvantage that the circuit configuration becomes complicated and the power consumption increases.

That is, in the conventional device, in order to obtain a parabolic wave-like correction signal So, a horizontal pulse is supplied to an integrating circuit (not particularly shown) and the waveform of this horizontal pulse is converted into a parabolic waveform. The peak value of (current) usually requires a current value of about IAp-p.

However, in order to obtain this current value, the conversion efficiency of the integrating circuit is poor, so the peak value of the horizontal pulse becomes considerably high, making it impossible to obtain the required current value easily, which requires a complicated circuit. I don't get it.

Furthermore, in order to adjust the phase of the obtained correction signal SO,
The integrating circuit is provided with a variable resistor for phase adjustment.

Therefore, the intervention of this variable resistor consumes a lot of power, and in particular, if the peak value of the horizontal pulse is set high in order to obtain the desired peak value, there is a fatal drawback that the power consumption increases even further.

The present invention eliminates the drawbacks of such conventional devices with a simple structure.

That is, in the present invention, a sinusoidal signal is skillfully used to obtain a correction signal having a waveform almost the same as the parabolic wave shown in FIG. 2, and the distortion of the electron beam can be corrected using this signal. The electron beam distortion correcting device according to the present invention will be described below with reference to the drawings, but in the example described below, a color cathode ray tube of one electron gun three beam system is used as the cathode ray tube.

Before explaining the apparatus of the present invention, an outline of the structure of this cathode ray tube will be explained.

FIG. 3 shows an electron gun installed in this cathode ray tube. In a plane parallel to the horizontal scanning direction, there are cathodes KR-KB that emit three electron beams BR, ~BB, and a plurality of cathodes KR-KB in this example.
The electron gun 3 is constituted by the grid electrodes G1 to G5 from G1 to G5 and a deflection plate 2 made up of four plates 2a to 2d.

Note that 4 is a phosphor formed on the phosphor screen, and 5 is an aperture grill.

Of the above-mentioned grid electrode group, a desired high voltage is applied to the third and fifth electrodes G3 and G5, the phosphor 4, and the aperture grille 5.

In the present invention, the distortion of the electron beam B (BR, -BB) emitted from the electron gun 3 having such a configuration is corrected, but this correction may be performed by either a magnetic field or an electric field. In this example, a case will be explained in which a correction magnetic field is obtained from a correction signal and distortion in the beam shape is corrected using this field.

In the present invention, as shown in FIG. 4, first and second magnetic field generating means 20A and 20B are provided, and these magnetic field generating means 20A and 20B are attached to the neck portion 6A of the cathode ray tube 6 (see FIG. 3). Fixed.

The mounting position is on the beam path before the electron beam B is deflected, and specifically, the mounting position is on the beam path before the electron beam B is deflected.
It is arranged at the neck portion 6A facing the electrode G4.

Here, since the fourth electrode G4 is an electrode constituting the main electron lens L, exactly three electron beams E3R-BB intersect, so a correction means is arranged on the fourth electrode G4, and the correction means is By supplying a correction current having a predetermined waveform, the beam shapes of the three electron beams BR-BB can be uniformly distorted into a desired shape.

Based on this reason, in the case of the electron gun 3 shown in FIG. 3, the first and second magnetic field generating means 20A and 20B are arranged on the neck portion 6A facing the fourth electrode G4. .

Therefore, when applying it to a black and white cathode ray tube, or when using a three-electron-gun, three-beam type cathode ray tube in which each electron beam BR to BB is emitted from a separate electron gun, there is a problem in applying it before deflection. These correction means may be placed anywhere in the section.

By the way, since the first and second magnetic field generating means 20A and 20B constituting the correction means have the same configuration, for example, only the first means 20A will be explained, and the second means 20B will be explained.
The subscript "b" is attached to the corresponding part, and the explanation thereof will be omitted.

As shown in FIG. 4, the first magnetic field generating means 20A has a pair of cores 11a and 12a each having a substantially U-shaped cross section, and these cores are arranged on the left and right through the neck portion 6A.

In this case, the arrangement relationship is selected such that the tube axis of the cathode ray tube 6 (in the illustrated example, the direction perpendicular to the plane of the paper) is located on the extension line of the central portions of the cores 11a and 12a.

A coil La is wound around these cores 11a and 12a with a predetermined number of turns, and when the electron beam B is deflected to both the left and right ends of the screen on the phosphor screen 1a, the cathode The first correction signal Sa is supplied to the coil La so that a magnetic field HV is generated which is directed downward on the left side of the electron beam B and upward on the right side when viewed from the side.

The second magnetic field generating means 20B is disposed perpendicular to the first magnetic field generating means 20A, and has a magnetic field H directed to the right above the electron beam B and to the left below the electron beam B.
The second correction signal Sb is supplied to the coil Lb so that H is generated.

Note that l3a and 13b indicate coil terminals.

In the present invention, the first
Both of the second correction signals Sa and Sb are sinusoidal signals.

Let us further explain these relationships with reference to FIG.

First, the first correction signal Sa is a horizontal pulse Sp (Fig. 5A
), that is, a horizontal frequency sine wave signal is used (B in the same figure).

Next, as the second correction signal Sb, even harmonics of the sine wave signal used as the first correction signal Sa are used.

In this example, the second harmonic is used (B in the same figure).
.

These first and second correction signals Sa and Sb are supplied to the respective coils La and Lb at appropriate levels, but in that case, the magnetic fields HV and HV generated based on the first and second correction signals Sa and Sb are The first and second correction signals Sa and Sb are adjusted so that the combined magnetic field H of HH is equal to the magnetic field based on the parabolic wave-like correction signal So shown in FIG.
The relative level of

Therefore, the first correction signal Sa and the second correction signal Sb
The respective signal levels are selected so that the hypothetical composite signal So with and is approximately equal to the correction signal So shown in FIG.

Note that each level is finally determined while observing the beam shape so that the shape of the electron beam reaching the phosphor 5 is not distorted even at the outermost portion of the phosphor screen.

By doing this, the shape of the electron beam B is deformed as shown by the dotted line in FIG. By using correction signals Sa and Sb (not shown), the shape distortion of the beam can be effectively corrected.

That is, as shown in FIG. 5B', the electron beam B in the electron gun 3 is vertically elongated at both the left and right ends of the screen, and becomes a perfect circle at the center of the screen. , it is possible to prevent deterioration of the beam shape at the periphery of the screen, and there is no unnecessary deterioration of the beam shape at the center of the screen.

Note that the above-mentioned first and second correction signals Sa and Sb can be obtained as follows.

The example shown in FIG. 6 is a case where a resonant circuit including quadrupole coils La and Lb is constructed and the resonant output thereof is utilized, 30A is the first resonant circuit, 30B is the second resonant circuit. Shows the circuit.

The first resonant circuit 30A is configured as a parallel resonant circuit including a coil La and a capacitor 31.

Note that 32 is an input terminal for the horizontal pulse Sp, 33 is an integrating circuit, Q is a drive transistor, 34 is a damper diode, and 35 is a capacitor for S-shaped correction.

On the other hand, the second resonant circuit 30B is composed of a coil Lb and a pair of capacitors 36a and 36b.

37 is an input terminal for the horizontal pulse Sp, and 38 is an integrating circuit.

Further, 39 indicates a DC weight circuit. If you do this,
Target correction signals Sa and Sb can be applied to the respective coils La and Lb.

In addition, when using a sine wave oscillator whose oscillation frequency is selected to be a horizontal frequency, this output may be used for the first correction signal, and therefore, by doubling this oscillation output,
The second correction signal Sb can be easily obtained.

In this oscillator, the oscillation output with the desired current value can be determined by making the constants of the oscillator itself variable or by installing an amplifier in the subsequent stage, so it can be obtained relatively easily from a circuit perspective. Therefore, as mentioned above, IAp
Correction signal S necessary to obtain a composite signal So of about −p
a, Sb are easily obtained.

As explained above, in the present invention, the first and second magnetic field generating means 20A and 20B are provided, sinusoidal correction signals Sa and Sb are supplied to these, and the shape of the electron beam is distorted by combining the resulting magnetic fields. It is designed to correct.

Therefore, in the present invention, first of all, since sinusoidal signals are used as the correction signals Sa and Sb, only a resonant circuit or an oscillator is required for generating the correction signals, and the circuit configuration is extremely simple. Since the sine wave signal itself is used as the correction signal, the correction signals Sa and Sb are used to obtain the necessary composite signal So with a current value of about IAp-p.
The current value has the characteristic that it can be obtained relatively easily.

Moreover, since there is no power-consuming resistor or the like interposed in the resonant circuit or oscillator for obtaining this correction signal, the present invention also has the practical effect of reducing power consumption.

Therefore, the device of the present invention is very convenient for practical use.

In addition, the magnetic field correction means can also be configured as a quadrupole, and furthermore, there is no need to strictly arrange the magnetic field correction means in the neck portion 6A, so that the structure is simple.

Further, according to the present invention, the power consumption in the circuit for generating the correction signal can be suppressed to a low level, and in addition to the effect of reducing the power consumption compared to the conventional device mentioned at the beginning, the first and second By changing the levels of the correction signals Sa and Sb,
Since any beam shape can be obtained within the correction magnetic field, the correction of the electron beam becomes more accurate.

It goes without saying that this electron beam distortion correction device is not limited to cathode ray tubes used in television receivers, but can also be applied to cathode ray tubes used in other equipment.

[Brief Description of the Drawings] Figure 1 is a diagram showing the shape of an electron beam on a fluorescent screen to provide an explanation for correcting electron beam shape distortion, and Figure 2 is a waveform diagram of a correction signal used for this beam correction. , FIG. 3 is a configuration diagram showing an example of an electron gun, FIG. 4 is a configuration diagram of the device of the present invention, FIG. 5 is a waveform diagram for explaining the same, and FIG. 6 is a connection diagram showing another example of the present invention. It is. B (BR, -BB) is an electron beam, So (Sa,
Sb) is a correction signal, HH, HV are these correction signals Sa,
Magnetic field generated by Sb, 3 is an electron gun, 4 is a phosphor, 6
is a cathode ray tube, 20A is the first magnetic field generating means, 20B is the second magnetic field generating means, 11.12 is the core, La and Lb are the coils, 30A
is the first resonant circuit, and 30B is the second resonant circuit.

Claims (1)

[Claims] 1 arranged opposite to each other with the electron beam in between on the path before entering the deflection magnetic field of the electron beam,
and a first correction magnetic field generating means having a pair of cores each having a coil attached thereto so as to generate magnetic fields in opposite directions, and the first correction magnetic field facing each other with the electron beam in between. a second correcting magnetic field generating means having a pair of cores arranged perpendicularly to the correcting magnetic field generating means and each having a coil wound thereon so as to generate magnetic fields in mutually opposite directions; A substantially sinusoidal current having a horizontal frequency is supplied to the correction magnetic field generating means of the second correction magnetic field generating means, and a substantially sinusoidal current having a horizontal frequency at least twice that of both the first and second correction magnetic field generating means is supplied to the second correction magnetic field generating means. An electron beam distortion correction device, wherein the direction of the magnetic field generated by the second correction magnetic field generating means is selected in such a direction that the electron beam extends in the vertical direction when the electron beam is deflected to the periphery.