KR20020037887A - Beam index type CRT - Google Patents

Abstract

PURPOSE: A beam index type cathode ray tube is provided to obtain a fine beam diameter by reducing the divergence effect of electron beam emitted from the main focus lens toward the phosphor screen. CONSTITUTION: A beam index type CRT comprises a phosphor screen(2) formed on an inner surface of a panel(4), and which has an index stripe(20); a funnel(6) coupled to a rear surface of the panel, and which has a transparent light receiving window(6a); an electron gun(10) mounted at an inner periphery of a neck part(8) extended from the funnel, and which has a cathode and a plurality of electrodes, and emits electron beams toward the phosphor screen; an optical detector(12) attached to the outer surface of the light receiving window, and which detects an index light emitted from the index stripes; an index circuit part(14) for converting the electrical signal detected by the optical detector into an index signal, synchronizing the index signal with a color signal and transmitting the correct color signal to the electron gun; and a unit for permitting the electron beam to have a fine beam diameter by controlling an equipotential line formed in the portion of the main focus lens opposed to the phosphor screen.

Description

Beam index type cathode ray tube {Beam index type CRT}

The present invention relates to a beam index type cathode ray tube, and more particularly, to a beam index type cathode ray tube capable of realizing a fine beam diameter by tilting an anode electrode of an electron gun to reduce the divergence effect of an electron beam.

In general, a beam index type cathode ray tube generates, focuses, and accelerates an electron beam from an electron gun, and scans it onto a fluorescent screen to implement an image, but the basic principle is the same as that of a conventional cathode ray tube. To perform the color selection function.

Since the beam index type cathode ray tube is not provided with a shadow mask, as shown in FIG. 7, a horizontal beam diameter having a limited size such that an electron beam scanned in a specific fluorescent film stripe 1a does not emit light adjacent to the fluorescent film stripe 1b. (D1) must be implemented. For this reason, the electron gun provided in the beam index type cathode ray tube should implement a very small horizontal beam diameter compared to the electron gun provided in the general cathode ray tube, and a finer horizontal beam diameter is required to realize high resolution.

Thus, in order to implement a fine beam diameter, conventionally, a funnel portion having a larger neck diameter than the conventional one is employed, or a method of expanding the main lens diameter of the electron gun using a magnetic focus method. However, when the diameter of the neck portion is increased, the focus characteristic is excellent, but the power required for electron beam deflection is greatly increased to increase the power consumption of the entire cathode ray tube, and both techniques have certain limitations in implementing the fine beam diameter.

Therefore, the present invention was devised to solve the above problems, and an object of the present invention is to incline the anode electrode of the electron gun to reduce the divergence effect of the electron beam passing through the main focus lens, so that a beam index type cathode ray beam can be realized. To provide a coffin.

1 is a cross-sectional view of a beam index type cathode ray tube according to the present invention.

2 is a sectional view of an electron gun.

3 to 4 and 6 are schematic diagrams for explaining the distribution of equipotential lines and the divergence relationship between electron beams.

5 is an enlarged cross-sectional view of the shield cup.

7 is a partially enlarged view of a fluorescent screen.

In order to achieve the above object, the present invention,

A fluorescent screen formed on an inner surface of the panel and having an index stripe;

A funnel portion coupled to the rear of the panel and forming a transparent light receiving window;

An electron gun mounted on an inner circumferential surface of the neck portion extending from the funnel portion, the electron gun having a cathode and a plurality of electrodes to emit an electron beam toward the fluorescent screen;

A photo detector attached to an outer surface of the light receiving window to detect index light emitted from an index stripe;

An index circuit for converting the electrical signal detected by the photo detector into an index signal and synchronizing it with a color signal to apply an accurate color signal to the electron gun;

Provided is a beam index type cathode ray tube including a means for finely curing an electron beam by densely controlling one equipotential line facing a fluorescent film screen in the main focus lens of the electron gun.

The means here consists of an anode electrode, in particular a shield cup, inclined at a predetermined angle towards the cathode from its edge toward the central beam through hole.

Therefore, when the cathode ray tube is operated, it is possible to more precisely control the equipotential lines formed in the direction of the fluorescent film screen from the main focus lens, that is, the equipotential lines that serve to emit the electron beam, thereby reducing the divergence effect of the electron beam passing through the main focus lens. It is possible to effectively reduce the beam diameter of the electron beam, especially the horizontal beam diameter.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a beam index type cathode ray tube according to the present embodiment. As shown in the present embodiment, a panel 4 having a fluorescent film screen 2 formed therein and a rear surface of the panel 4 are coupled to each other. A funnel portion 6 and a neck portion 8, an electron gun 10 mounted on an inner circumferential surface of the neck portion 8 to emit an electron beam toward the fluorescent screen 2, and a light receiving window of the funnel portion 6. (6a) a photo detector 12 attached to an outer surface to detect index light, an index circuit portion 14 electrically connected to the photo detector 12 and the electron gun 10, and means for fine beam curing the electron beam It includes.

In the fluorescent film screen 2, a plurality of R, G, and B fluorescent film stripes 18 are sequentially positioned between the black matrix films 16, and index stripes 20 are formed at predetermined intervals.

The index stripe 20 receives an electron beam and is excited to emit light pulses (index light) in the near ultraviolet region, and the emitted index light is transmitted through the transparent light receiving window 6a of the funnel portion 6 to the photodetector 12. And then converted into an electrical signal.

The index circuit 14 processes the electrical signal converted by the photo detector 12 as an index signal, controls the degree of deflection and the current density, and transmits an accurate color signal to the electron gun 10 to perform accurate color implementation.

As described above, the electron gun 10 that receives the correct color signal through the index circuit unit 14 is a single electron gun that emits a single electron beam. As shown in FIG. 2, the cathode K and the cathode (e.g. A control electrode (G1) and a screen electrode (G2) for controlling and electron beaming the hot electrons emitted from K), a focus electrode (G3) and an anode electrode (G4) for focusing and accelerating the electron beam, and the cathode (K) and It includes a pair of supports 24 for aligning a plurality of electrodes in a row.

For example, the electron gun is a uni-bipotential type, and the focus electrode G3 is composed of the first to third focus electrodes G3-1, G3-2, and G3-3. The anode electrode G4 surrounding the third focus electrode G3-3 includes a shield cup 22 at one end facing the screen.

The hot electrons emitted from the cathode K are electron beamed to form an electric field due to the voltage difference applied to each electrode, and then focused and accelerated toward the fluorescent film screen 2, in particular, the focus electrode G3 is formed of the first and the first electrodes. The same voltage is applied to the three focus electrodes G3-1 and G3-3, and a voltage lower than that of the first focus electrode G3-1 is applied to the second focus electrode G3-2, and between the respective focus electrodes. Form a prefocus lens.

In addition, the anode electrode G4, particularly the shield cup 22, receives a high pressure of about 32 kV from a built-in graphite film (not shown) applied to the inner surface of the neck portion 8, and the third focus electrode G3-3. A main focus lens is formed between the anode electrode G4, in particular the shield cup 22, to finally accelerate the electron beam to the fluorescent screen 2.

At this time, an equipotential line concave with respect to the electron beam incidence direction is formed in the right portion (inside the anode electrode, region A in the drawing) facing the fluorescent film screen 2 in the main focus lens. Since the equipotential lines have a concave lens effect that emits an incident electron beam as indicated by a dotted arrow, as shown in FIG. 4, the more closely the equipotential lines are directed toward the main focus lens center, the less the divergence effect of the electron beam is. The electron beam diameter can be reduced.

Therefore, in order to reduce the divergence effect of the electron beam emitted toward the fluorescent film screen 2, as shown in FIG. 5, the shield cup 22 constituting the right portion of the main focus lens is formed to have a predetermined inclination. In more detail, the shield cup 22 is formed to be inclined at a predetermined angle α toward the cathode K toward its center through the beam passing hole 22a at its edge.

As a result, as shown in FIG. 6, when the cathode ray tube is operated, the equipotential lines formed inside the anode electrode G4 can be densely controlled toward the center of the main focus lens due to the inclination of the shield cup 22. The divergence effect can be reduced.

Next, the actual electron beam diameter change caused by the shape change of the anode electrode G4, in particular, the shield cup 22 will be described in detail.

First, the voltage characteristics provided to the control electrode to the anode electrode in the beam index type cathode ray tube according to the prior art are shown in Table 1 below, wherein the anode electrode forms a beam through hole having a 6 mm inner diameter in the center thereof without inclination. It is formed perpendicular to the electron beam traveling direction.

Applied voltage (V) Cathode voltage (K) 95 Control electrode G1 0 Screen electrode G2 1,000 First focus electrode G3-1 7,280 Second focus electrode G3-2 0 Third focus electrode G3-3 7,280 Anode electrode G4 32,000

Under the above conditions, the equipotential lines formed on the right side of the main focus lens, that is, inside the shield cup, are diffused in a wide distribution with respect to the center of the main focus lens, and pass through the main focus lens having such an equipotential distribution. The horizontal and vertical beam diameters of the final electron beams reached are shown in Table 2 below.

Horizontal beam diameter (mm) Vertical beam diameter (mm) 0.3871 1.6400

On the other hand, in the beam index type cathode ray tube according to the present embodiment, the shield cup 22 of the anode electrode G4 moves the cathode K toward the center beam through hole 22a at its edge as shown in FIG. 5. Form an inclination angle (α), for example the inclination angle may be made of 12 °.

At this time, the shield cup 22 forms a beam through hole having the same diameter as the shield cup according to the prior art, and the voltage characteristics provided to the control electrodes G1 to the anode electrode G4 are the same as those in Table 1 above. Do.

Under the above conditions, the equipotential lines formed on the right side of the main focus lens, that is, inside the shield cup 22 are more densely distributed toward the center of the main focus lens, thereby reducing the divergence effect of the electron beam. The horizontal and vertical beam diameters of the final electron beams passing through the main focus lens and reaching the fluorescent screen are shown in Table 3 below.

Horizontal beam diameter (mm) Vertical beam diameter (mm) 0.3518 1.4393

As a result, when comparing Table 2 and Table 3 above, the present embodiment having the inclined shield cup 22 realizes a finer electron beam diameter compared to a general electron gun having a shield cup perpendicular to the electron beam traveling direction. It can be seen that the horizontal beam diameter of the electron beam is more effectively reduced.

Table 4 below shows measurement values of the horizontal beam diameter and the vertical beam diameter of the electron beam according to the change of the inclination angle α of the anode electrode G4. In the table, the horizontal beam diameter reduction rate and the vertical beam diameter reduction rate are shown in Table 2 above. Comparison with the horizontal beam diameter and the vertical beam diameter.

Here, the voltage characteristics applied to each electrode in the electron gun 10 are the same as in Table 1, and in addition to the change in the inclination angle of the anode electrode G4, the shapes of each electrode including the anode electrode G4 are all the same as above.

Tilt angle α (°) Horizontal beam diameter (mm) Vertical beam diameter (mm) Horizontal beam reduction rate (%) Vertical beam reduction rate (%) Test 1 6 0.3614 1.4543 6.64 11.32 Test 2 12 0.3518 1.4393 9.12 12.24

As described above, the present embodiment can easily implement a fine beam diameter by forming an inclination in the shield cup 22 of the electron gun, thereby effectively preventing the electron beam from emitting adjacent other color fluorescent film stripe and reducing color purity, which is more advantageous for high resolution. Has an advantage.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications and changes can be made within the scope of the claims and the detailed description of the invention and the accompanying drawings. Naturally, it belongs to the scope of the invention.

As described above, the beam index type cathode ray tube according to the present invention can implement a fine beam diameter by reducing the diverging effect of the electron beam emitted from the main focus lens toward the fluorescent screen by giving a fine inclination to the anode electrode of the electron gun, particularly the shield cup. Accordingly, it is possible to implement the fine beam diameter by modifying only the shape of the anode electrode without adding a separate device for implementing the fine beam diameter, and it is possible to effectively prevent the degradation of color purity by emitting adjacent other fluorescent film stripe.

Claims (3)

A fluorescent film screen formed on an inner surface of the panel and having an index stripe; A funnel portion coupled to a rear surface of the panel to form a transparent light receiving window; An electron gun mounted to an inner circumferential surface of the neck portion extending from the funnel portion, the electron gun having a cathode and a plurality of electrodes to emit an electron beam toward the fluorescent screen; A photo detector attached to an outer surface of the light receiving window to detect index light emitted from an index stripe; An index circuit for converting the electrical signal detected by the photo detector into an index signal and synchronizing it with a color signal to apply an accurate color signal to the electron gun; And a means for finely curing the electron beam by finely controlling one of the equipotential lines facing the fluorescent film screen in the main focus lens of the electron gun. The method of claim 1, And a cathode that the electron gun emits hot electrons, and a control electrode, a screen electrode, a focus electrode, and an anode electrode that are disposed to face the cathode at a predetermined interval and receive a corresponding voltage to control the electrons. The method of claim 1, And the means is provided on the anode electrode, the beam index type cathode ray tube consisting of a shield cup inclined at a predetermined angle toward the cathode toward the center beam through hole at the edge thereof.