JP2003077405A - Cathode-ray tube and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode-ray tube which can make dynamic convergence correction without bringing forth spot distortion or degradation in the focus. SOLUTION: For the sake of deflecting two electron beams E1, E2 passing a main-focus lens, an electron gun 7 is structured with a convergence electrode 10 equipped with an inside electrode plate 11 with a first voltage impressed and an outside electrode plate 12 opposing the inner electrode plate 11 with a second voltage lower than the first impressed, and a parabolic focus electrode G4 synchronized with horizontal deflection period and amplitude modulated at vertical deflection period with dynamic focus voltage impressed. By combining the focus electrode G4 and the outside electrode plate 12 of the convergence electrode 10 with capacitor C, the second voltage impressed on the outside electrode plate is dynamically changed to make dynamic convergence correction.

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 having an electron gun with a convergence electrode and a display device using the same.

[0002]

2. Description of the Related Art In television receivers and the like, there is a demand for a display device having a larger screen size in order to provide viewers with a large-screen, realistic and powerful image. In the current color cathode ray tube, a large-sized display device having a screen size equivalent to 40 type has been realized. However, since such a large-sized display device weighs over 100 kg, it is difficult to install it in a general home. Therefore, a rear projector device using a cathode ray tube is known as a device that allows a large screen to be enjoyed easily even in a general home.

In the rear type projector device, red,
By using three monochromatic cathode ray tubes corresponding to each color of green and blue, the image projected on each cathode ray tube is enlarged and projected by a lens on a transmissive screen. As a result, a color image in which images corresponding to the respective colors are combined is displayed on the screen, so that the combined image (color image) can be viewed through the transmissive screen.

By the way, in the case of such a rear type projector device, the screen size of the monochromatic cathode ray tube is as small as 7 type to 9 type, and the image projected on this small screen is enlarged and projected on a large screen. However, it is difficult to obtain sufficient brightness. Therefore, as one of the methods of improving the brightness, a method of increasing the number of electron beams in a monochromatic cathode ray tube from one to a plurality of electron beams has been proposed.

However, in order to increase the number of electron beams, when each electron beam is scanned on the screen of the cathode ray tube, it is necessary to concentrate (converge) the electron beams at one point in all areas on the screen. . The reason for this is that if the electron beam is not concentrated on one point on the screen, that is, if there is a so-called convergence shift, the image will appear to be blurred at that portion. So, as a technique to correct the deviation of convergence on the screen,
The dynamic convergence correction technique by the following methods (1) to (3) is known.

(1) A method for performing dynamic convergence correction by distorting the deflection magnetic field of a deflection yoke into a pincushion type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field.

(2) Convergence yoke on the cathode ray tube
(Convergence Yoke) is installed and a dynamic convergence correction is performed by supplying a correction signal to this convergence yoke.

(3) A method of performing dynamic convergence correction by supplying a convergence voltage modulated by an external transformer to a convergence plate of an electron gun through a coaxial cable.

[0009]

However, in the method described in (1) above, the deflection magnetic field is distorted, so that the spot shape of the electron beam is distorted in the peripheral portion of the screen and the focus is deteriorated. was there.

In the method described in (2) above, since the electron beam is deflected by the quadrupole magnetic field formed by the convergence yoke, the quadrupole magnetic field is generated in the peripheral portion of the screen where the correction amount is large. There was a problem that the spot shape of the electron beam was distorted and the focus was deteriorated due to the influence of.

On the other hand, in the method described in (3) above, since the correction voltage is directly applied to the convergence plate of the electron gun, it is necessary to superimpose the convergence correction signal on the DC voltage of about 95% of the anode voltage. Therefore, an external transformer that realizes this becomes extremely expensive because it is necessary to sufficiently perform insulation processing against high voltage.

The present invention has been made to solve the above problems, and its main purpose is to provide a cathode ray tube capable of performing dynamic convergence correction without causing spot distortion and focus deterioration and a cathode ray tube using the same. To provide the display device that has been used.

[0013]

A cathode ray tube according to the present invention deflects two electron beams passing through a main focus lens, and an inner electrode plate to which a first voltage is applied, and this inner electrode. An electron gun provided with a convergence electrode having an outer electrode plate facing the plate and having a second voltage lower than the first voltage applied thereto, and a parabola synchronized with the horizontal deflection period and amplitude-modulated in the vertical deflection period. And a voltage applying means for applying a uniform convergence voltage to the outer electrode plate of the convergence electrode. Further, the display device according to the present invention uses the cathode ray tube having the above configuration.

In the cathode ray tube having the above structure and the display device using the same, when the two electron beams that have passed through the main focus lens are deflected by the convergence electrodes, the amplitude modulation is performed in synchronization with the horizontal deflection period and at the vertical deflection period. By applying the parabolic convergence voltage thus generated to the outer electrode plate of the convergence electrode, the second voltage applied to the outer electrode plate dynamically changes with respect to the first voltage applied to the inner electrode plate. Come to do. Accordingly, the deflection amounts of the two electron beams at the convergence electrode dynamically change according to the waveform of the convergence voltage, so that it becomes possible to perform the dynamic convergence correction using the convergence electrode.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention when applied to a monochromatic cathode ray tube used in, for example, a rear type projector device will be described in detail below with reference to the drawings.

FIG. 1 is a schematic diagram showing the overall structure of a cathode ray tube according to an embodiment of the present invention. In FIG. 1, the main body of the cathode ray tube 1 is composed of a glass bulb including a panel portion 2, a funnel portion 3 and a neck portion 4. A fluorescent screen is formed on the inner surface of the panel unit 2 in a predetermined pattern. In addition, the funnel portion 3 is provided with an anode terminal 5. A high voltage (anode voltage) is applied to the anode terminal 5 from an anode power source 6 which is a high voltage power source.

On the other hand, an electron gun 7 is incorporated in the neck portion 4. This electron gun 7 has two cathodes 8 and 9,
Electrons (beams) emitted from these cathodes 8 and 9
Is provided with a plurality of grid electrodes G1, G2, G3, G4, G5 for controlling the amount, moving speed, trajectory, etc., and a convergence electrode 10.

Each of the cathodes 8 and 9 has a base metal coated or impregnated with an electron emitting substance, a cylindrical holding member for holding the base metal, and a heater inserted in the cylinder of the holding member. Then, by heating the base metal to a predetermined temperature with a heater, electrons (thermoelectrons) are emitted. These cathodes 8 and 9 are arranged side by side in the Y-axis direction which is the vertical axis direction of the screen of the cathode ray tube 1.

The respective grid electrodes G1 to G5 are arranged in series in the central axis direction of the electron gun 7 (the tube axis direction of the cathode ray tube 1), and the first grid electrode G1 is arranged in order from the side closest to the cathodes 8 and 9. The second grid electrode G2, the third grid electrode G3, the fourth grid electrode G4, and the fifth grid electrode G5.

The convergence electrode 10 is arranged at the tip of the electron gun 7 adjacent to the last-stage grid electrode G5. The convergence electrode 10 has one inner electrode plate 11 and a pair of outer electrode plates 12 arranged outside the inner electrode plate 11 so as to face the inner electrode plate 11. Further, the pair of outer electrode plates 12 are arranged so as to face each other with the inner electrode plate 11 sandwiched therebetween.

Here, the third grid electrode G3 and the fourth grid electrode
The grid electrode G4 and the fifth grid electrode G5 are located on the trajectory of the electron beam and are the main focus lens (electron lens).
Is formed. In forming this main focus lens, a dynamic focus voltage is applied to the fourth grid electrode G4 by the focus power supply 13 and the dynamic focus signal generator 14, and an anode is applied to the third grid electrode G3 and the fifth grid electrode G5. A high voltage supplied from the power supply 6 via the anode terminal 5 is applied.

The dynamic focus voltage is obtained by modulating the focus voltage supplied from the focus power supply 13 with the dynamic focus signal generator 14, and its waveform diagram is shown in FIG. As shown, the dynamic focus voltage has a parabolic waveform synchronized with the horizontal deflection period (1H), and its amplitude is modulated with the vertical deflection period (1V). By the way, ΔH in the figure
Represents the potential difference in the horizontal deflection cycle, and ΔV represents the potential difference in the vertical deflection cycle.

On the other hand, in the convergence electrode 10, the third grid electrode G3 is provided with respect to the inner electrode plate 11.
The same high voltage as that of the fifth grid electrode G5 (same potential) is applied, and the high voltage applied to the inner electrode plate 11 (hereinafter referred to as the first voltage) is applied to the pair of outer electrode plates 12.
A voltage slightly lower than that (hereinafter referred to as the second voltage) is applied.

The second voltage applied to the outer electrode plate 12 is divided by the two resistors R1 and R2. The variable resistor VR is connected in series to the resistor R2. The variable resistance VR is for adjusting the voltage applied to the outer electrode plate 12 so that the two electron beams E1 and E2 having the cathodes 8 and 9 as emission sources converge at the center of the screen.

Here, in the cathode ray tube 1 according to this embodiment, the convergence electrode 1 uses the dynamic focus voltage shown in FIG. 2 as the convergence voltage.
It is configured to include voltage applying means for applying to the outer electrode plate 12 of 0. This voltage applying means is configured by coupling the fourth grid electrode G4 and the outer electrode plate 12 with the capacitance C.

As a concrete structure example of the electrostatic coupling, FIG.
As shown in (A) and (B), a conductive (metal or the like) tubular body 1 having an inner diameter larger than the outer diameter of the fourth grid electrode G4.
5 is provided, and the fourth grid electrode G4 is coaxially inserted and arranged in the cylindrical body 15. Then, the cylindrical body 15 and the outer electrode plate 1
2 is electrically connected with a lead or the like. As a result, the fourth
Since a capacitance is provided in the gap between the grid electrode G4 and the cylindrical body 15, a state in which the fourth grid electrode G4 and the outer electrode plate 12 are electrostatically coupled is obtained. Further, a dielectric (insulator) may be interposed between the fourth grid electrode G4 and the cylindrical body 15 so as to have a capacitance.

As another example of the structure of electrostatic coupling, FIG.
As shown in (A) and (B), a conductive film 17 is formed on the outer surface of one of the outer electrode plates 12 via an insulating film 16, and the conductive film 17 and the fourth grid electrode G4 are electrically connected. To do. As a result, the insulating film 16 has a capacitance, so that the fourth grid electrode G4 and the outer electrode plate 12
A state in which and are electrostatically coupled is obtained.

Next, the operation function of the cathode ray tube 1 having the above structure will be described.

First, the two electron beams E1 and E2 having the respective cathodes 8 and 9 as emission sources are supplied to the third grid electrode G.
After converging at the center of the main focus lens formed by the third, fourth grid electrode G4 and the fifth grid electrode G5, the convergence electrode 10 once spreads outward.
Incident on. At this time, the electron beam E1 having the cathode 8 as the emission source passes between the outer electrode plate 12 and the inner electrode plate 11 on one side (the lower side in FIG. 1), and the electron beam E2 having the cathode 9 as the emission source is the other. Outer electrode plate 1 (upper part of FIG. 1)
It passes between 2 and the inner electrode plate 11.

In passing the electron beams E1 and E2 in this manner, the first voltage (high voltage) is applied to the inner electrode plate 11.
And the second voltage is applied to the pair of outer electrode plates 12, the electron beams E1 and E2 are deflected inwardly in accordance with the potential difference between them. The deflection amount of the electron beams E1 and E2 by the convergence electrode 10 increases as the difference (potential difference) between the first voltage and the second voltage increases.

Therefore, by appropriately adjusting the voltage applied to the outer electrode plate 12 with the variable resistor VR, the two electron beams E1 and E2 can be converged at the central portion of the screen. However, when the two electron beams E1 and E2 are deflected in the horizontal and vertical directions by the deflection magnetic field of the deflection yoke (not shown) under the condition that the voltage applied to the outer electrode plate 12 is constant, the cathode ray tube 1 On the screen, a deviation of convergence occurs as shown in FIG. That is, although the two electron beams E1 and E2 concentrate at one point at the intersection of the X axis and the Y axis, which is the center of the screen, the deviation of the convergence increases as the X axis end and the Y axis end are approached. Become. As a result, the peripheral part (corner part) of the screen
Therefore, the deviation of the convergence becomes the maximum.

On the other hand, the fourth electrode which becomes the focus electrode
In the configuration in which the grid electrode G4 and the outer electrode plate 12 of the convergence electrode 10 are electrostatically coupled, a convergence voltage having a waveform similar to the dynamic focus voltage applied to the fourth grid electrode G4 is applied to the outer electrode plate 12. . In such a case, the first voltage applied to the inner electrode plate 11 is set as a fixed voltage, and the second voltage applied to the outer electrode plate 12 dynamically changes according to the waveform diagram shown in FIG. Become.

By the way, in the actual circuit operation, the resistance R
1, in which the dynamic focus voltage is superimposed on the voltage divided by R2 and adjusted by the variable resistor VR,
Convergence voltage is applied to the outer electrode plate 12, but resistances R1 and R
2 and the voltage component due to the variable resistor VR are held constant.

Here, in the waveform diagram shown in FIG. 2, within the horizontal deflection period (1H) in which the electron beams E1 and E2 are scanned along the X-axis direction of the screen, the voltage level changes from the high voltage side to the low voltage side. After that, the voltage changes from the low pressure side to the high pressure side. In this case, the voltage level becomes maximum when the X-axis end of the screen is beam-scanned and becomes minimum when the intersection with the Y-axis is scanned. Thereby, the convergence electrode 10
The deflection amount (inward degree) of the electron beams E1 and E2 due to becomes smaller as the beam scanning position approaches the X-axis end of the screen.

In the vertical deflection period (1V) in which the electron beams E1 and E2 are scanned along the Y-axis direction of the screen, the voltage level changes from the high voltage side to the low voltage side and then from the low voltage side to the high voltage side. fluctuate. In this case, the voltage level becomes maximum when the Y-axis end of the screen is beam-scanned, and is minimum when the intersection with the X-axis is beam-scanned. Thereby, the electron beam E by the convergence electrode 10
The deflection amounts (inward degrees) of 1 and E2 become smaller as the beam scanning position approaches the Y-axis end.

As described above, the convergence electrode 10
The deflection amounts of the two electron beams E1 and E2 in (3) dynamically change according to the waveform of the dynamic focus voltage (convergence voltage). Therefore, the two electron beams E1, which have passed through the convergence electrode 10,
E2 becomes more concentrated as the beam scanning position moves away from the center of the screen (the intersection of the X axis and the T axis). As a result, the dynamic convergence correction is realized, so that the two electron beams E1 and E2 can be concentrated at one point in the entire area of the screen.

Further, when the two electron beams E1 and E2 pass through the convergence electrode 10, the respective electron beams E1 and E2 are deflected without being concentrated by the magnetic field, so that the beams on the screen are deflected. It is possible to reduce spot distortion. As a result, it is possible to simultaneously improve the focus characteristic and correct the dynamic convergence.

Further, since the fourth grid electrode G4 and the outer electrode plate 12 are electrostatically coupled to each other so that a convergence voltage can be applied to the outer electrode plate 12, an external device for dynamic convergence correction is separately provided. No need to provide. Therefore, it is possible to significantly reduce the cost and the power consumption.

In the above embodiment, an electron gun of a type in which one electron beam is extracted from one cathode has been described as an example, but other than this, a plurality of electron beams can be emitted from one cathode. It may be provided with a so-called multi-beam type electron gun.

In the above embodiment, an example of application to a monochromatic cathode ray tube used in a rear type projector device has been described, but the present invention is not limited to this, and a color cathode ray tube used in a television receiver or the like. It is also applicable to.

FIG. 6 is a schematic view showing an example of application to a trinitron type color cathode ray tube. This type of color cathode ray tube has three cathodes 2 corresponding to each color of red, green and blue.
1, 22, 23 and a plurality of grid electrodes G1 to G5,
An in-line type electron gun 25 having a convergence electrode 24 is provided. The three electron beams R, G, and B emitted from the electron gun 25 in an in-line arrangement irradiate the fluorescent screen 27 through a blind-shaped aperture grill 26.

The three electron beams R, G, and B, which use the cathodes 21, 22, and 23 as emission sources, are supplied to the third grid electrode G3, the fourth grid electrode G4, and the fifth grid electrode G.
After passing through the main focus lens formed by 5, the light enters the convergence electrode 24. The convergence electrode 24 has a pair of inner electrode plates 28 arranged to face each other, and a pair of outer electrode plates 29 arranged to face the outside of each inner electrode plate 28.

In the convergence electrode 24 having the above structure, the red electron beam R passes between the inner electrode plate 28 and the outer electrode plate 29 (downward in the figure), and the green electron beam G is The electron beam B for blue passes between the pair of inner electrode plates 28, and passes between the other inner electrode plate 28 (upper part of the drawing) and the outer electrode plate 29. At this time, the fourth grid electrode G4 and the outer electrode plate 29 are coupled by the capacitance C, and the dynamic focus voltage applied to the fourth grid electrode G4 is applied to the outer electrode plate 29 as a convergence voltage. By doing so, it is possible to obtain the same effects as the above-described embodiment.

[0044]

As described above, according to the present invention, the voltage applying means for applying the parabolic convergence voltage synchronized with the horizontal deflection period and amplitude-modulated with the vertical deflection period to the outer electrode plate of the convergence electrode is provided. With the provision, it is possible to dynamically change the second voltage applied to the outer electrode plate and concentrate the two electron beams at one point in each part (center part, peripheral part, etc.) on the screen. This makes it possible to improve focus characteristics and simultaneously achieve dynamic convergence correction.

[Brief description of drawings]

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

FIG. 2 is a waveform diagram of a dynamic focus voltage.

FIG. 3 is a diagram illustrating a specific structural example of electrostatic coupling.

FIG. 4 is a diagram illustrating another structural example of electrostatic coupling.

FIG. 5 is a diagram illustrating a deviation of convergence on a screen.

FIG. 6 is a diagram illustrating another application example of the present invention.

[Explanation of symbols]

1 ... Cathode ray tube, 5 ... Anode terminal, 6 ... Anode power supply,
7 ... Electron gun, 8, 9 ... Cathode, 10 ... Convergence electrode, 11 ... Inner electrode plate, 12 ... Outer electrode plate, 13 ...
Focus power supply, 14 ... Dynamic focus signal generator, 15 ... Cylindrical body, 16 ... Insulating film, 17 ... Conductive film, C ...
Capacitance, G1 to G5 ... Grid electrode

Claims (3)

[Claims] 1. An inner electrode plate for deflecting two electron beams that have passed through a main focus lens, a first voltage is applied to the inner electrode plate, and an inner electrode plate facing the inner electrode plate.
An electron gun having a convergence electrode having a second voltage applied to the second electrode lower than the above voltage, and a parabolic convergence voltage synchronized with the horizontal deflection cycle and amplitude-modulated with the vertical deflection cycle. A cathode ray tube comprising: a voltage applying unit that applies a voltage to the outer electrode plate of the electrode. 2. The electron gun includes a focus electrode which forms the main focus lens and which is applied with a parabolic dynamic focus voltage synchronized with a horizontal deflection cycle and amplitude-modulated in a vertical deflection cycle. 2. The cathode ray tube according to claim 1, wherein the voltage applying unit is configured by electrostatically coupling the focus electrode and the outer electrode plate of the convergence electrode. 3. An inner electrode plate for deflecting two electron beams passing through a main focus lens, a first voltage is applied to the inner electrode plate, and the inner electrode plate facing the inner electrode plate and the first electrode plate.
An electron gun having a convergence electrode having a second voltage applied to the second electrode lower than the above voltage, and a parabolic convergence voltage synchronized with the horizontal deflection cycle and amplitude-modulated with the vertical deflection cycle. A display device using a cathode ray tube comprising a voltage applying unit that applies a voltage to the outer electrode plate of the electrode.