JPH07312182A - Electron gun for cathode ray tube - Google Patents

Abstract

(57) [Summary] [Object] To provide an electron gun for a cathode ray tube capable of suppressing deterioration of spot distortion due to deflection distortion at an edge portion of a screen. [Structure] A fifth electrode G ₅ and a sixth electrode for focusing three electron beams 9R, 9G, 9B emitted from in-line array cathodes KR, KG, KB on the phosphor screen 5, and beams on both sides. Passage openings 17R and 18R, 17B and 18B are arranged non-coaxially. The sixth electrode G ₆ supplies a constant voltage (V _F). The fifth electrode G ₅ is supplied with a dynamic voltage (V _F + Δv _f ) having a downwardly convex waveform which is clamped so that the maximum voltage becomes equal to V _F.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, a color picture tube,
The present invention relates to an electron gun for a cathode ray tube used in a color display device or the like.

[0002]

2. Description of the Related Art In a color cathode ray tube, three electron beams emitted from an electron gun are focused on one point on a screen for scanning. At that time, the electron beams are focused on the central part of the screen. I am trying. However, in this state, the electron beams are excessively concentrated (overconvergence state) at the edge of the screen where the distance from the electron gun is large, and the three electron beams are not aligned. Therefore, in order to adjust the concentration of the electron beams at the edge portion of the screen, conventionally, the deflection magnetic field by the deflection yoke spreads the electron beams in the array direction (x direction) of the cathodes so that the concentration of the three electron beams is adjusted. It is being appreciated.

[0003]

However, in the case of such a conventional method, since a force that diverges the electron beam in the x direction and converges it in the y direction acts, deflection distortion occurs and the beam spot becomes horizontally long. It has the drawback of being shaped. When the beam spot is deteriorated due to such deflection distortion, not only the resolution characteristics of the cathode ray tube are deteriorated, but also it becomes difficult to manufacture a cathode ray tube having a wide deflection angle, and the deflection yoke is also complicated. .

The present invention has been made in view of the above-mentioned problems of the conventional example, and an object of the present invention is to provide an electron gun for a cathode ray tube capable of suppressing deterioration of spot distortion due to deflection distortion at an end portion of a screen. It is in.

[0005]

According to the present invention, first and second focusing electrodes for focusing three electron beams emitted from a cathode ray tube on a fluorescent screen are provided on both sides of the above electron beam. Trajectories of the beams on both sides are formed by arranging openings for passing the beams so as not to partially overlap each other, and by a lens electric field formed according to a dynamic voltage supplied between the first and second focusing electrodes. Is changed to the focusing direction.

In this case, it is also possible to shift the centers of the openings of the same shape, which face each other, of the first and second focusing electrodes.

Further, the diameters of the openings facing each other of the first and second focusing electrodes can be made different.

Further, the first and second focusing electrodes are sequentially arranged from the cathode toward the phosphor screen, and the openings on both sides of the first focusing electrode are arranged outside the openings on both sides of the second focusing electrode. The second focusing electrode is supplied with a predetermined constant voltage, while the first focusing electrode is supplied with the same voltage as the voltage supplied to the second focusing electrode when scanning the edge of the screen and becomes the minimum voltage when scanning the screen center. It can also be configured to supply a dynamic voltage.

Furthermore, the first and second focusing electrodes are sequentially arranged from the cathode toward the phosphor screen, and the openings on both sides of the first focusing electrode are arranged outside the openings on both sides of the second focusing electrode. While supplying a predetermined constant voltage to the second focusing electrode, the voltage applied to the first focusing electrode is higher than the voltage applied to the second focusing electrode when scanning the edge of the screen and is applied to the second focusing electrode when scanning the screen center. It can also be configured to supply a dynamic voltage that is minimized at a voltage lower than the supplied voltage.

In addition, it is also possible to form a quadrupole lens electric field for correcting astigmatism caused by the deflection magnetic field.

[0011]

In the case of the present invention having such a structure, when the beams on both sides of the three electron beams pass through the non-coaxial openings provided in the first and second focusing electrodes, Two
The orbit is changed in the focusing direction by the lens electric field formed according to the dynamic voltage supplied between the electrodes. Therefore, according to the present invention, the focal length of the electron beam can be changed according to the distance between the electron gun and the fluorescent screen without using the deflection yoke.

In this case, the beams on both sides can be passed very easily by displacing the centers of the openings of the same shape which face each other of the first and second focusing electrodes or by making the diameters of the openings which face each other different. Are arranged so as not to partially overlap with each other, and the above-mentioned trajectory change and focusing of the electron beam are performed.

Further, the first and second focusing electrodes are sequentially arranged from the cathode toward the phosphor screen, and the openings on both sides of the first focusing electrode are arranged outside the openings on both sides of the second focusing electrode. The second focusing electrode is supplied with a predetermined constant voltage, while the first focusing electrode is supplied with the same voltage as the voltage supplied to the second focusing electrode when scanning the edge of the screen and becomes the minimum voltage when scanning the screen center. If the dynamic voltage is supplied, the potential difference between the first and second focusing electrodes is maximized when the screen center is scanned, and the trajectories of the beams on both sides are changed so that the electron beam is relatively moved. On the other hand, the beam is focused at a position closer to the screen, and when scanning the screen edge, the potential difference between the first and second focusing electrodes becomes 0, the trajectory of the beam does not spread, and the beam is focused at a position relatively distant from the electrode.

Furthermore, the first and second focusing electrodes are sequentially arranged from the cathode toward the phosphor screen, and the openings on both sides of the first focusing electrode are arranged outside the openings on both sides of the second focusing electrode. While supplying a predetermined constant voltage to the second focusing electrode, the voltage applied to the first focusing electrode is higher than the voltage applied to the second focusing electrode when scanning the edge of the screen and is applied to the second focusing electrode when scanning the screen center. If the dynamic voltage is supplied at a voltage lower than the supplied voltage, the dynamic voltage is minimized to maximize the potential difference between the first and second focusing electrodes when the screen center is scanned, and the trajectories of the beams on both sides are expanded. Direction is changed so that the electron beam is focused at a point relatively close to the electrodes, while the voltage of the second focusing electrode becomes higher than that of the first focusing electrode when scanning the edge of the screen. The orbit of Is changed to a direction, the electron beam is focused at a distance from the more relatively electrode.

In addition, if the quadrupole lens electric field for correcting the astigmatism caused by the deflection magnetic field is formed, the spot shape of the electron beam on the fluorescent screen is corrected and the spot distortion is reduced. To do.

[0016]

Embodiments of the present invention will be described below with reference to FIGS.

FIG. 5 shows a schematic structure of a cathode ray tube to which the present invention is applied. As shown in the figure, an electron gun 3 to be described later is arranged in the neck portion 2 of the tube body 1 of the cathode ray tube. On the other hand, a fluorescent screen 5 is formed on the inner surface of the panel 4 of the tubular body 1,
A color selection mechanism 6 is attached near the fluorescent screen 5.
Further, a deflection yoke 8 is attached so as to surround the funnel 7 of the tube body 1, and the three electron beams 9 emitted from the electron gun 3 are deflected by the deflection yoke to scan the screen.

FIG. 2 shows an electron gun 3 for a cathode ray tube according to this embodiment.
It shows the configuration of. As shown in the figure, the electron gun 3 in this embodiment by way of type U-UPF, composed of the first electrode to eighth electrode G ₁ ~G ₈ which sequentially arranged coaxially.
Each of the _first to eighth electrodes G _{1 to} G ₈ is provided with an opening for passing the electron beam 9.

In the present embodiment, the red color on the phosphor screen 5,
Three cathodes K for irradiating each green or blue phosphor
R, KG, KB are arranged in-line, for example, integrally arranged,
Electron beam 9 (9R, 9R) from each cathode KR, KG, KB
G, 9B) is emitted.

The first electrode G ₁ adjacent to the cathodes KR, KG, KB is a control grid electrode for controlling the electron beams 9R, 9G, 9B emitted from the cathodes KR, KG, KB. Then, a second electrode G ₂ as an acceleration electrode is provided adjacent to the first electrode G _1, and the second electrode G ₂ is connected to a fourth electrode G ₄ as an acceleration electrode by a lead wire 10.

On the other hand, the third, fifth and seventh electrodes G ₃ , G ₅
And G ₇ are first focusing electrodes, which are connected to the dynamic voltage generating circuit 12 and the DC power source 13 via the lead wire 11. Further, a sixth electrode G ₆ as a second focusing electrode is provided between the fifth electrode G ₅ and the seventh electrode G _7, and is connected to the DC power supply 13 via the lead wire 14.

Further, an eighth electrode G ₈ is provided adjacent to the seventh electrode G ₇ . The eighth electrode G ₈ plays a role of a final accelerating electrode, is attached to the insulated cup member 15, and is connected to the anode button 16 for supplying high voltage (HV).

The third, fifth and seventh electrodes which are the first focusing electrodes.
Pole G₃, G_FiveAnd G₇And a sixth electrode which is the second focusing electrode
G₆Is a medium voltage for focus applied later.
Be done. In this case, the third, the fifth and the first focusing electrodes
7 electrodes G₃, G_Five, G₇Is a dynamic voltage (V_F+
Δv_f) Is applied, and the sixth electrode G that is the second focusing electrode ₆
Is a constant voltage (V_F) Is supplied. In this case, V_F
= 5 to 9 kV is preferable.

In the present embodiment, the sixth electrode G ₆ and the seventh electrode G ₆
A known quadrupole lens electric field is formed by the electrode G ₇ . That is, the sixth electrode G ₆ and the seventh electrode G
By changing the shape of the opening of _7, a quadrupole lens electric field having an astigmatism in the opposite direction that cancels the astigmatism due to the deflection magnetic field is formed. For example, in the case of forming a circular opening 18, 20 to the sixth electrode G ₆ as shown in FIGS. 1B and C, as shown in FIG. 3, the openings 22 of oblong shape to the seventh electrode G ₇ ( 22R, 22G, 22B) are formed. Thus, the spot distortion of the electron beam on the phosphor screen 5 can be significantly reduced.

FIG. 1 shows an essential part of this embodiment.
As shown in the figure, in this embodiment, the electron beam 9
The position and shape (diameter) of the openings of the fifth electrode G ₅ and the sixth electrode G ₆ are made different in order to correct the trajectory.

In the embodiment shown in FIG. 1B, the circular openings for passing the red and blue electron beams 9R, 9B are the openings 17R, 17 of the fifth electrode G _5.
The gap between the openings 18R and 18B of the sixth electrode is wider than that of B. In this case, the green electron beam 9G
The openings 17G and 18G for passing through are respectively located on the same axis.

On the other hand, in the embodiment shown in FIG. 1C, the openings 19R and 19B for passing the red and blue electron beams 9R and 9B of the sixth electrode G ₆ are oblong and the inner diameter thereof is The five electrodes G ₅ are formed to be larger than the inner diameters of the openings 20R and 20B. In this case, an opening 17G for passing the green electron beam 9G,
18G is located on the same axis. The openings 19G, 2 for passing the green electron beam 9G
Regarding 0G, each is circular and is arranged coaxially.

A high voltage (20 to 35 kV) is applied to the eighth electrode G _8.
And the seventh electrode G ₇ and the eighth electrode G ₈ form a focusing lens electric field.

The same effects as described below can be obtained by using either of the embodiments shown in FIGS. 1B and 1C. However, in the case of the example shown in FIG. 1B, the inner core jig is difficult to pass because the openings 17R, 18R and 17B, 18B are eccentric, whereas in the case of the example shown in FIG. ，
Since 20 is formed coaxially, there is an advantage that it is easy to assemble using an inner core jig.

Next, the operation and effect of this embodiment will be described.
Explain. FIG. 1D shows the first and second focusing electrodes provided.
It is a wave form diagram which shows the focus voltage. Figure 1D and Figure
As shown in FIG. 2, the third, fifth and
7 electrodes G ₃, G_Five, G₇Via lead wire 11,
Maximum voltage is V_FBelow clamped to equal
Dynamic voltage of convex waveform (V_F+ Δv_f) Supplied
Be done. In this case, as shown in FIG.
Sometimes takes the maximum value, and minimum when scanning the screen center
The waveform is set to take a value. In addition, dynamic electric
Pressure (V_F+ Δv_f) Is, for example, a blanking section
The pulse waveform is superimposed on and synchronized with the horizontal and vertical deflection periods.
A pseudo parabolic waveform (not shown) is used.
However, it is not limited to this and may be modified as necessary.
Yes. On the other hand, the sixth electrode G which is the second focusing electrode₆To Lee
Constant voltage V_FIs supplied.

The potential difference (Δv _f ) between the first and second focusing electrodes is 0 ≦ Δv _f ≦ −300 (V) to 0 ≦ Δv _f ≦ −1500.
(V) It is adjusted to be about V.

In the case of this embodiment having such a configuration, FIG.
As can be seen from D, when scanning the screen center, the potential difference (Δv _f ) between the fifth and sixth electrodes G ₅ and G ₆ having the configuration shown in FIG. 1B or C is maximized. Therefore, as shown in FIG. 1A, the orbits of the red and blue electron beams 9R and 9B spread outside the parallel direction (in the x direction).
Furthermore, the electron beams 9R, 9G, 9B are focused by the convex lens electric field formed between the seventh and eighth electrodes G ₇ , G ₈ , and the three electron beams 9R, 9G, 9B are converted into the eighth beam.
Focus at a point at a predetermined distance from the electrode G ₈ . Then, for example, the convergence is adjusted so that this point coincides with the screen center on the phosphor screen 5.

On the other hand, as can be seen from FIG. 1D, the screen
The fifth and sixth electrodes G when scanning the edges of the_Five, G₆
Potential difference (Δv_f) Becomes 0, the fifth and sixth power
Pole G _Five, G₆There is no potential gradient between them. as a result,
Each electron beam 9R, 9G, 9B has fifth and sixth electrodes
G_Five, G₆In order to go straight between the
The windows 9R and 9B run in the screen center as shown in FIG.
Eighth electrode G inside when checking₈On both sides formed
It passes through the openings 21R and 21B. Therefore, this implementation
According to the example, compared with the case of scanning the screen center,
Electrode G₈Three electron beams 9R,
9G and 9B can be focused, and the fifth and
Sixth electrode G_Five, G₆Potential difference (Δv_f) Can be adjusted
As a result, three electrons are emitted even at the screen edge on the phosphor screen 5.
Beams 9R, 9G and 9B can be focused
It

According to the present embodiment having such a configuration, it is not necessary to perform the convergence by the deflection yoke 8, so that the deterioration of the spot shape due to the deflection distortion can be prevented at the end portion of the screen.

Further, according to this embodiment, since deflection distortion does not occur, it is possible to easily manufacture a cathode ray tube having a wide deflection angle.

Further, since it is not necessary to perform convergence by the deflection yoke 8, there is also an effect that a simple and highly accurate deflection yoke can be manufactured at low cost.

FIG. 6 shows another embodiment of the electron gun for a cathode ray tube according to the present invention. Parts corresponding to those in the above embodiment will be described with the same reference numerals. The electron gun 3 of this embodiment has the same basic configuration as that of the above-mentioned embodiments, and the only difference is the waveform of the voltage supplied to the first and second focusing electrodes.

As shown in FIG. 6B, in the case of this embodiment, the sixth electrode G which is the second focusing electrode, for example, is the same as in the above embodiment.
A constant voltage (V _F) is supplied to _6. On the other hand, the voltage (V _F1 ) higher than the voltage (V _F ) supplied to the second focusing electrode is applied to the third, fifth and seventh electrodes G ₃ , G ₅ and G ₇ which are the first focusing electrodes. The dynamic voltage (V _F1 + Δv _f ) clamped to the maximum voltage is supplied. The waveform and amplitude of this dynamic voltage (V _F1 + Δv _f ) may be the same as those in the above-mentioned embodiments, or may be changed appropriately.

As shown in FIG. 6B, in this embodiment, when scanning the screen center, the fifth electrode G ₅
Since the electrode G ₆ has a higher potential, the red and blue electron beams 9R and 9B spread outward as in the above-described embodiment, and as a result, the three electron beams 9 on the phosphor screen 5 are formed.
R, 9G, 9B can be focused.

On the other hand, when scanning the edge portion of the screen, the voltage of the sixth electrode G ₆ becomes lower than that of the fifth electrode G _5, so as shown in FIG. 6A, the electron beams 9R for red and blue are emitted. ，
9B comes closer to the inside. As a result, the convex lens electric field formed between the seventh and eighth electrodes G ₇ and G ₈ weakens the convergence effect and lengthens the focal length of the electron lens system.
The three electron beams 9R, 9G, and 9B can be focused on the above, and the same effect as the above-mentioned embodiment can be achieved. Other configurations and operations are the same as those of the above-described embodiment, and detailed description thereof will be omitted.

The present invention is not limited to the above-mentioned embodiment, and various modifications can be made.

For example, in the above-described embodiment, the case where there are eight electrodes has been described as an example, but the present invention is not limited to this and can be applied to an electron gun having various numbers of electrodes. In that case, it may be either a unipotential type or a bipotential type.

Although the quadrupole lens electric field is formed in the above embodiment, it is not always necessary to use the quadrupole lens. However, if a quadrupole lens is used, the deterioration of the spot distortion of the electron beam can be further prevented.
It should be noted that it is also possible to adopt a configuration in which the lens for changing the trajectories of the electron beams on both sides and the quadrupole lens are shared, and as a result, the configuration is further simplified.

Further, the shapes of the openings of the first and second focusing electrodes and the final accelerating electrode are not limited to those in the above-mentioned embodiment, and various shapes can be adopted.

Furthermore, it is possible to use both the electron beam concentration by the conventional deflection yoke and the electron beam concentration by the above-mentioned embodiment. Even in this case, it is possible to reduce the spot distortion due to the deflection yoke.

[0046]

As described above, according to the present invention, the openings for passing the beams on both sides of the three electron beams are arranged in the first and second focusing electrodes so as not to partially overlap each other. Since the beam electric field on both sides is changed to the focusing direction by the lens electric field formed according to the dynamic voltage supplied between the first and second focusing electrodes, the deflection yoke is not used for the screen The electron beam can be concentrated at each portion, and as a result, the deterioration of the spot shape due to the deflection distortion at the screen edge can be reduced.

By displacing the openings of the same shape for passing the beams on both sides through the first and second focusing electrodes, or by making the diameters of the openings facing each other different,
The openings for passing the beams on both sides can be easily arranged so as not to partially overlap with each other, and the deterioration of the spot shape due to the deflection distortion can be reduced.

Further, the first and second focusing electrodes are sequentially arranged from the cathode toward the phosphor screen, and the opening portions on both sides of the first focusing electrode are arranged outside the opening portions on both sides of the second focusing electrode. The second focusing electrode is supplied with a predetermined constant voltage, while the first focusing electrode is supplied with the same voltage as the voltage supplied to the second focusing electrode when scanning the edge of the screen and becomes the minimum voltage when scanning the screen center. By configuring so as to supply the dynamic voltage, it is possible to greatly reduce the deterioration of the spot shape due to the deflection distortion at the screen edge portion.

Furthermore, the first and second focusing electrodes are sequentially arranged from the cathode toward the phosphor screen, and the openings on both sides of the first focusing electrode are arranged outside the openings on both sides of the second focusing electrode. While supplying a predetermined constant voltage to the second focusing electrode, the voltage applied to the first focusing electrode is higher than the voltage applied to the second focusing electrode when scanning the edge of the screen and is applied to the second focusing electrode when scanning the screen center. By providing a dynamic voltage that is the lowest at a voltage lower than the supplied voltage, it is possible to completely prevent the deterioration of the spot shape due to the deflection distortion at the screen edge.

In addition, if the quadrupole lens electric field for correcting the astigmatism caused by the deflection magnetic field is formed, the spot distortion of the electron beam can be further reduced and the resolution can be improved. .

Moreover, according to the present invention, since a deflection distortion does not occur, a cathode ray tube having a wide deflection angle can be easily manufactured, and further, since it is not necessary to perform convergence by a deflection yoke, it is simple and high. There is also an effect that an accurate deflection yoke can be manufactured at low cost.

[Brief description of drawings]

FIG. 1A is a main part configuration diagram of an embodiment of an electron gun for a cathode ray tube according to the present invention. B is an explanatory diagram showing an example of openings of fifth and sixth electrodes of the same Example. FIG. C is an explanatory view showing another example of the openings of the fifth and sixth electrodes of the same Example. FIG. D is a waveform diagram of the voltage supplied to the first and second focusing electrodes.

FIG. 2 is a schematic configuration diagram of the embodiment.

FIG. 3 is a front view showing an opening shape of a seventh electrode of the example.

FIG. 4 is an explanatory diagram showing changes in the orbit of the electron beam in the same example.

FIG. 5 is a schematic cross-sectional configuration diagram of a cathode ray tube to which the present invention is applied.

6A is a main part configuration diagram of another embodiment of the electron gun for a cathode ray tube according to the present invention. FIG. B is a waveform diagram of the voltage supplied to the first and second focusing electrodes of the same Example.

[Explanation of symbols]

3 Electron Gun 5 Fluorescent Screen 17, 18, 19, 20 Opening G ₁ First Electrode G ₂ Second Electrode G ₃ Third Electrode G ₄ Fourth Electrode G ₅ Fifth Electrode G ₆ Sixth Electrode G ₇ Seventh Electrode G ₈ Eighth electrode KR, KG, KB Cathode

Claims (6)

[Claims] 1. The first and second focusing electrodes for focusing the three electron beams emitted from the cathode on the phosphor screen are provided with openings for passing beams on both sides of the electron beam. Firstly, the first
And an electron gun for a cathode ray tube, wherein the orbits of the beams on both sides are changed in a focusing direction by a lens electric field formed according to a dynamic voltage supplied between the second focusing electrodes. 2. The electron gun for a cathode ray tube according to claim 1, wherein the centers of the openings of the same shape, which face each other, of the first and second focusing electrodes are offset from each other. 3. The electron gun for a cathode ray tube according to claim 1, wherein the diameters of the openings facing each other of the first and second focusing electrodes are made different. 4. The first and second focusing electrodes are sequentially arranged from the cathode toward the phosphor screen, and the openings on both sides of the first focusing electrode are arranged outside the openings on both sides of the second focusing electrode. The second focusing electrode is supplied with a predetermined constant voltage, while the first focusing electrode is supplied with the same voltage as the voltage supplied to the second focusing electrode when scanning the edge of the screen and becomes the minimum voltage when scanning the screen center. The electron gun for a cathode ray tube according to claim 2, wherein a dynamic voltage is supplied. 5. The first and second focusing electrodes are sequentially arranged from the cathode toward the phosphor screen, and the openings on both sides of the first focusing electrode are arranged outside the openings on both sides of the second focusing electrode. The second focusing electrode is supplied with a predetermined constant voltage, while the first focusing electrode is supplied with a voltage higher than the voltage supplied to the second focusing electrode when scanning the edge of the screen and is supplied to the second focusing electrode when scanning the screen center. The electron gun for a cathode ray tube according to claim 2 or 3, wherein a dynamic voltage that is minimized at a voltage lower than a predetermined voltage is supplied. 6. The electron gun for a cathode ray tube according to claim 1, wherein a quadrupole lens electric field for correcting astigmatism caused by the deflection magnetic field is formed.