JP2005129544A - Cathode-ray tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cathode-ray tube maximizing the action of a VM coil acting in synchronization with the differential signal of a video signal. <P>SOLUTION: In this cathode-ray tube including a cathode 3 to emit an electron beam toward a phosphor screen, an electron gun in which an anode electrode 9 on the screen side and a focus electrode on the cathode side, and the VM 18 coil acting in synchronization with the video signal of a circuit mounted on the neck part of the cathode-ray tube, the focus electrode 8 on which a fixed focus voltage is impressed comprises a set of three or more electrodes continuously disposed, and when the total of the length of the focus electrodes is set as L, and the intervals between the focus electrodes are set as 'g1' and 'g2', 4 mm < L < 30 mm, 0.6 mm < g1 < 1.2 mm, and 0.6 mm < g2 < 1.2 mm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cathode ray tube, and more particularly to a color cathode ray tube in which the structure and shape of an electrode are improved in order to reduce the spot diameter that affects the focus of an electron beam.

FIG. 1 is a schematic configuration diagram of a conventional cathode ray tube.
Referring to FIG. 1, a large number of electrodes are formed on an in-line electron gun for a cathode ray tube. The electrodes are positioned at a certain interval so as to be perpendicular to the passage path of the electron beam 13 so that the electron beam generated at the cathode 3 is controlled with a certain intensity and reaches the screen 17. ing.

  Specifically, three cathodes 3 that are independent from each other, a first electrode 4 that is a common grid of the three cathodes 3 arranged at a certain distance from the cathode, and a certain distance from the first electrode. The second electrode 5, the third electrode 6, the fourth electrode 7, the fifth electrode 8, and the sixth electrode 9 are configured in this order.

  The upper part of the sixth electrode 9 is configured in the order of the shield cup 10 to which B.S.C11 is attached, which serves to fix the electron gun on the neck of the tube while electrically connecting the electron gun and the tube. An in-line type electron gun is shown.

  Explaining the operation of the electron gun, the electron gun emits electrons from the stem pin 1 of the heater 2 built in the cathode 3, the electrons are controlled by the first electrode 4 of the control electrode, and the electron beam 13 is controlled, and the acceleration electrode The electron beam 13 is accelerated by the second electrode 5, and the electron beam is partially focused and converged by the focusing lens at the tip formed between the second electrode 5, the third electrode 6, the fourth electrode 7 and the fifth electrode 8. Accelerated.

  Also, in order to form a quadrupole lens for compensating astigmatism generated by the deflection yoke, a part of the electrode forming the main lens is called a focus electrode, and a variable voltage is synchronized with the deflection signal. The applied sixth electrode 9 and the seventh electrode 10 called the anode electrode cause the electron beam to be mainly focused and accelerated and pass through the shadow mask 15 formed inside the phosphor screen 16. It strikes the phosphor screen 16 and emits light.

  A deflection yoke 12 that deflects the electron beam 13 emitted from the electron gun to the entire surface of the screen 17 is positioned outside the electron gun to implement the screen.

  A VM (Velocity modulation; hereinafter referred to as a coil) 18 that operates in synchronization with the video signal of the circuit is mounted on the neck portion of a conventional cathode ray tube with an electron gun. The coil is applied to reduce the spot diameter, which is the main aspect of the present invention.

  Conventionally, factors affecting the spot diameter on the screen in the design characteristics of the electron gun include lens magnification, space charge repulsion, and spherical aberration characteristics of the main lens.

The operation of the above characteristics will be described in more detail.
The influence of the lens magnification on the spot diameter (D _x ) is such that the basic voltage conditions, focal length, and length of the electron gun are determined. The effect is also very small.

The influence of the space charge repulsive force is a phenomenon of spot diameter expansion due to mutual repulsion and collision between electrons in the electron beam. To reduce the increase of the spot diameter (D _st ) due to space charge repulsive force, It is advantageous to design such that the traveling angle (hereinafter referred to as “divergence angle”; α) is large.

The influence of the spherical aberration characteristic of the main lens is an expansion development of the spot diameter (D _ic ) due to a focal length difference between electrons passing through the paraxial axis and electrons passing through the far axis, and the space charge repulsive force On the contrary, the smaller the divergence angle of the electron beam incident on the main lens, the smaller the spot diameter on the screen.

As described above, the spot diameter (D _t ) on the screen is generally represented by the sum of three types of elements.

  In particular, as a method of reducing spherical aberration while reducing space charge repulsion, it is best to enlarge the main lens diameter.

  By enlarging the main lens diameter, even if an electron beam with a large divergence angle is incident, the expansion of the spot due to spherical aberration can be reduced, and the space charge repulsion after passing through the main lens can also be reduced. Implementation becomes possible.

  FIG. 2 shows a change in the spot diameter depending on the main lens diameter as an experimental result showing the above contents.

  As can be seen from the graph shown in FIG. 2, the spot diameter on the screen can be reduced because the increase in the spot diameter due to the spherical aberration of the main lens decreases as the main lens diameter increases.

  In general, the fifth electrode to which a high voltage is applied and the sixth electrode to which a variable voltage is applied in synchronization with the deflection signal are collectively called a focus electrode, and the length of the focus electrode is the voltage of the electron gun. It is an important factor that determines the ratio (%: focus / high pressure). Inclusion of the sixth electrode may compensate for the astigmatism of the deflection yoke, but the sixth electrode is applied when there is little need to improve the resolution and the sharpness of the screen periphery. Sometimes it doesn't.

  As a method of enlarging the main lens portion, a method of mechanically enlarging the hole diameter of the main lens forming electrode, a method of increasing the depth of the electrostatic field control electrode body that performs the lens correcting action, and the like were presented.

  However, since it is almost impossible to increase the hole diameter of the electrode mechanically because of the limiting element of the neck diameter of φ29.1 mm, there is a difficulty in improving the focus quality.

  Therefore, in order to reduce the spot diameter on the screen and improve the resolution, the circuit that drives the cathode ray tube installed in the chassis is appropriately operated, and the differential signal of the video signal that scans the electron beam on the screen is obtained. It is applied in synchronization with a coil installed at the neck of a cathode ray tube with an electron gun. As a result, the resolution and sharpness on the screen can be improved by modulating the electron beam at a speed at which it is uniformly deflected by the deflection magnetic field of the deflection yoke.

FIG. 3 schematically shows the operating principle of the VM coil.
In order to maximize the circuit resolution improvement method, the total length of the electrodes to which the conventional fixed focus voltage is applied is sufficiently short, and the velocity modulation magnetic field generated by the current applied in synchronization with the video signal of the coil is generated. There is a problem that a sufficient interval has to be formed so as to invade effectively.

  As described above, the structure of the conventional electron gun is inappropriate for maximizing the effect of the coil.

  Normally, the center of the magnetic field generated by the coil is located in the vicinity of the fifth electrode to which a relatively high voltage is applied while being fixed, but the length of the electrode is increased in order to match the voltage ratio necessary for the design. It is common.

  Increasing the length of the electrodes has the advantages of cost savings and simplification of the production process, compared to the case where small parts are continuously installed.

  However, such a simplified structure of the electron gun using long electrodes acts as an element that impedes the improvement in resolution by weakening the speed modulation effect due to the magnetic field of the coil.

  An object of the present invention is to solve the conventional problems, and is composed of two or more electrodes in which focus electrodes to which a fixed focus voltage is applied are continuously arranged, and between the focus electrodes to which the fixed focus voltage is applied. It is an object of the present invention to provide an electron gun that maximizes the action of a VM coil that operates in synchronization with a differential signal of a video signal by maintaining an appropriate interval.

  An electron gun for a color cathode ray tube according to the present invention includes a cathode that emits an electron beam toward a phosphor screen, an anode electrode on the screen side, and a focus electrode on the cathode side, and the position of the focus electrode is a magnetic field. The focus electrode to which a fixed focus voltage is applied is continuously arranged in a cathode ray tube including a VM coil which is mounted on the neck portion of the cathode ray tube at the center of the tube and operates in synchronization with the video signal of the circuit. When the total length of the focus electrodes is “L” and the total distance between the electrodes is “g”, it is (g × 100) / L = 5-30. (%) Is satisfied.

  According to the present invention, it is possible to improve the screen resolution by reducing the size of the screen spot diameter in the horizontal direction by 15 to 30%.

  As a result of producing and evaluating the sample under the above conditions, the spot size on the screen has a reduction effect of about 15 to 30% in the horizontal direction corresponding to the conventional electron gun.

  By applying the structure of the electron gun according to the present invention, in order to reduce the spot diameter that greatly affects the focus, two or more pieces of the focus electrode to which the fixed focus voltage is applied are maintained as they are. By dividing the electrodes into the same voltage and forming an interval between the electrodes of 0.6 to 1.2 mm, the size of the screen spot diameter in the horizontal direction can be reduced by 15 to 30%.

  Moreover, since it can be applied in a short period of time with a low cost, the quality of focus can be improved early.

Hereinafter, an electron gun for a color cathode ray tube according to the present invention will be described in detail with reference to the accompanying drawings.
First, in order to maximize the circuit resolution improvement method of the VM coil, the length of the focus electrode to which the fixed focus voltage where the center of the magnetic field generated by the VM coil is located is increased in order to match the high voltage ratio. There is a need to. Further, a sufficient electrode interval should be formed so that a velocity modulation magnetic field due to a current applied in synchronization with the video signal of the VM coil can effectively enter.

  Therefore, the electron gun main lens structure of the present invention includes an electrode having an opening common to three electron beams and three electron beam passage holes similar to the conventional electron gun structure as shown in FIG. The plate-like electrostatic field control electrode body and the gap-like electrode are laminated, and the electrodes are electrically connected through a welding process or the like, so that the variable voltage synchronized with the high voltage and the deflection signal Is applied.

  Of the main electrodes conventionally composed of an anode electrode on the screen side and a focus electrode on the cathode side, the focus electrode is classified into an electrode for applying a variable focus voltage and an electrode for applying a fixed focus electrode.

  Among them, the fixed focus electrodes for applying the fixed focus voltage are arranged in two or more.

  4A and 4B are structural diagrams of a conventional electron gun, and FIG. 4C is a structural diagram of an electron gun according to the present invention, in which a focus electrode 28 to which a fixed focus voltage is applied is continuous. It is an arranged electron gun structure.

  4D is a structural diagram of the electron gun according to the present invention, in which a focus electrode 31 to which a variable focus voltage is applied and a focus electrode 28 to which a fixed focus voltage is applied are continuously arranged. The structure of the electron gun is shown.

  FIG. 4 (c) shows a cathode 23 to which a video signal is applied, a second electrode 25 that attracts electrons emitted from the cathode to gather and travel in the screen direction, and a certain level that an electron beam is applied to the cathode. A first electrode 24 that stops emission of electrons when a voltage corresponding to the video signal is not applied is disposed, a third electrode 26 that applies a relatively high voltage, and a first electrode that applies a relatively low voltage. There are four electrodes 27 and focus electrodes 28a, 28b, 28c for applying a relatively high fixed voltage.

  Then, the main lens is formed so as to scan the electron beam on the screen by the ninth electrode 29 to which a high voltage is applied, thereby forming the screen of the cathode ray tube.

  4D has the same structure as that of FIG. 4C, and a focus voltage that is varied in synchronization with the deflection signal of the deflection yoke is applied to compensate for the astigmatism difference generated by the deflection yoke magnetic field. Thus, an eighth electrode 31 forming a quadrupole lens is further arranged.

  The eighth lens 31 and the ninth electrode 29 to which a high voltage is applied form a main lens so as to scan the screen with an electron beam, thereby forming a screen of a cathode ray tube.

  FIG. 6 shows the structure of an electron gun having a focus electrode for applying a fixed focus voltage according to the present invention.

  The main electrode includes an anode electrode 29 and a focus electrode 28, and the focus electrode 28 includes an electrode 31 that applies a variable focus voltage and an electrode 28 that applies a fixed focus voltage.

  Among them, two or more focus electrodes 28 for applying a fixed focus voltage are continuously arranged together with the focus electrodes 28a, 28b and 28c of FIGS. 4c and 4d, and the total length L of the continuously arranged focus electrodes 28 is 4 mm or more and 30 mm. Has the following values:

  At this time, assuming that the total of the gaps g1 and g2 between the focus electrodes 28 arranged continuously is g, the following formula (g × 100) / L = 5 to 30 (%) is satisfied.

  The experimental results for the focus electrode 28 to which a fixed focus voltage satisfying the above equation is applied are shown in the graph of FIG.

  FIG. 5 shows changes in the spot diameter of the screen due to the focus electrode to which a fixed focus voltage is applied and a coil that operates in synchronization with the differential signal of the video signal.

  FIG. 5A shows the number of intervals of the focus electrodes to which the fixed focus voltage located at the center of the working magnetic field of the electron gun electrode, in particular the coil, is applied, that is, the fifth electrode 28a, the sixth electrode 28b and the fifth electrode in FIG. It is a graph showing numbers for forming intervals like the seven electrodes 28c and the reduction amount of the screen spot by the velocity modulation magnetic field of the coil, and it can be seen that the effect increases as the number of the intervals increases.

  FIG. 5B shows the distance between the focus electrodes 28 and the reduction amount of the screen spot due to the velocity modulation magnetic field of the coil. The effect of the coil when the distance is about 0.6 to 1.2 mm. It can be seen that is maximized.

  FIG. 5C is a graph showing the relationship between the total length of the electron gun and the velocity modulation magnetic field of the coil. It can be seen that there is a section proportional to the electron gun inserted into the cathode ray tube.

  Therefore, if the data of FIG. 5 is analyzed, the number of intervals between the focus electrodes 28 should be one or more, and the width of the interval between the focus electrodes 28 is 0.6 to 1. The 2 mm level is the most effective, and the longer the total length of the electron gun, the more advantageous, but the effect is not great if it exceeds a certain level.

It is the schematic of a common cathode ray tube. It is a graph which shows the change of the spot diameter by the main lens diameter. It is a figure which shows the operating principle of VM coil. It is a figure which compares and demonstrates the structure of the conventional electron gun, and the structure of the electron gun by this invention. It is a figure explaining the change of the spot diameter of a screen by the coil which acts synchronizing with the focus electrode to which a fixed focus voltage is applied, and the differential signal of a video signal. It is a figure which shows the structure of the electron gun by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stem pin 2 Heater 3, 23 Cathode 4, 24 1st electrode 5, 25 2nd electrode 6, 26 3rd electrode 7, 27 4th electrode 8
8 5th electrode 9, 29 6th electrode 10 Shield cup 11 B.S.C
12 Deflection yoke 13 Electron beam 15 Shadow mask 16 Phosphor screen 17 Screen 28 Focus electrode

Claims (1)

A cathode that emits an electron beam toward the phosphor screen, an electron gun that includes an anode electrode on the screen side and a focus electrode on the cathode side, and the neck of the cathode ray tube with the position of the focus electrode being the center of the magnetic field In a cathode ray tube equipped with a VM (Velocity Modulation) coil that is attached to the circuit and operates in synchronization with the video signal of the circuit;
The electron gun includes three focus electrodes to which a fixed focus voltage is applied,
When the total length of the focus electrodes to which the fixed focus voltage is applied is “L” and the distance between the focus electrodes to which the fixed focus voltage is applied is “g1” and “g2”, 4 mm <L < A cathode ray tube with 30 mm, 0.6 mm <g1 <1.2 mm, and 0.6 mm <g2 <1.2 mm.

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