KR20020062485A - Cathod Ray Tube - Google Patents

Abstract

The anode consists of a large diameter cylindrical portion on the phosphor screen side and a small diameter cylindrical portion on the cathode side, and the focus electrode has a diameter larger than that of the small diameter cylindrical portion of the anode and a small diameter having a smaller diameter than the small diameter cylindrical portion of the anode. The cylindrical part consists of a combined cylindrical part, and the large diameter cylindrical part of a focus electrode is coaxially arranged in the large diameter cylindrical part of an anode, and the cathode electrode tube which the 1st electrode arrange | positioned opposite to the cathode side of a focus electrode is electrically connected in the tube with an anode. In the axial length of the focus electrode LG4 (mm) and the distance from the end surface of the phosphor screen side of the focus electrode to the center of the phosphor screen is LP (mm), the relationship between LG4 and LP is -LP + 184.9 ≥ and a 922.41, LP ≥ 131.7 - LG4 ≥ 0.0004 LP 3 - 0.1571 LP 2 + 21.006 LP.

Description

Cathode Ray Tube {Cathod Ray Tube}

The present invention relates to a cathode ray tube, in particular, in a single electron gun type cathode ray tube such as a cathode ray tube for a projection TV, by optimizing the electron gun, the cathode ray tube made possible to shorten the overall length of the cathode ray tube without impairing its focus characteristics. It is about.

Projection-type TV receivers generally use three cathode ray tubes, each dedicated for red, green, and blue primary color image reproduction, and three primary color images obtained by these three cathode ray tubes (5.5 inches as an example of a phosphor screen diagonal diameter). Is magnified and projected onto a screen (40 inches as an example of a screen diagonal diameter) using an optical lens or a mirror, and three primary color images are polymerized on the screen to form a color image.

As an electron gun of a cathode ray tube for a projection TV, there is an electron gun for cathode ray tubes described in Japanese Patent Publication No. 58-31696. This electron gun will be described with reference to FIG. In Fig. 5, the control lattice electrode 102, the auxiliary focusing electrode 103, the acceleration electrode 104, the first anode 110, and the second anode 111, which insulate and support the cathode 101, are common to these. It is insulated and supported by the insulating rod 112 of these, and these are accommodated in the valve neck part 107. As shown in FIG.

The second anode 111 has a small diameter supporting end 113 at an end edge on the side of the first anode 110 and is supported by an insulating rod 112 adjacent to the small diameter supporting end 113. In addition, the conductive tongue member 114 attached to the distal end of the second anode 111 receives a high voltage applied through the conductive film 115 deposited on the inner surface of the valve neck 107. 111).

The first anode 110 is located within the neck portion 116 penetrating without contacting the support end 113 having a smaller diameter of the second anode 111 and a cylindrical portion having a larger diameter of the second anode 111. The tip portion 117 has a large diameter having an outer diameter larger than the inner diameter of the support end 113 having a small diameter. The main lens is formed between the tip portion 117 having a large diameter and the cylindrical portion having a large diameter of the second anode 111.

According to such an electrode structure, not only can the roundness of the second anode 111 and the coaxiality between the first anode 110 and the second anode 111 be improved, but also the second anode 111 can be made good. The inner diameter can be approximated to the inner diameter of the valve neck portion 107. Therefore, a large-diameter main lens with less spherical aberration is obtained without increasing the valve neck portion diameter, and the beam spot diameter can be made very small.

In Fig. 5, reference numeral 118 denotes a face plate, and 119 denotes a phosphor screen formed on the inner surface of the face plate 118.

Projection-type TV receivers requiring three cathode ray tubes and projection optics have generally suffered from increased external dimensions. Thus, there has been a strong desire for miniaturization of cathode ray tubes, in particular shortening the overall length of cathode ray tubes, without compromising focus characteristics.

However, in the electron gun for cathode ray tubes described in Japanese Patent Application Laid-open No. 58-31696, no shortening of the overall length of the cathode ray tube was taken into consideration.

When the axial length of the electron gun is shortened to shorten the overall length of the cathode ray tube, there is a problem in general that the deterioration of the focus characteristic cannot be avoided.

It is an object of the present invention to provide a cathode ray tube which makes it possible to shorten the overall length of a cathode ray tube without compromising its focusing characteristics by optimizing the electron gun.

1 is a side view of a cathode ray tube according to an embodiment of the present invention, a part of which is shown in cross-sectional view;

FIG. 2 shows the 5% beam spot diameter obtained by computer simulation using the distance LP from the phosphor screen side end face of the focus electrode G4 to the center of the phosphor screen and the length LG4 of the focus electrode as parameters. One vote.

FIG. 3 shows the results of a 5% beam spot diameter obtained by computer simulation using the distance LP from the cathode end surface of the focus electrode G4 to the center of the phosphor screen and the length LG4 of the focus electrode as parameters. Plot graph.

Fig. 4 is a diagram showing a permissible range of the relationship between the fluorescent surface distance LP and the focus electrode length LG4 in the present invention.

Fig. 5 is a sectional view of a cathode ray tube actually mounted with a conventional electron gun.

<Explanation of symbols for the main parts of the drawings>

1: neck part

2: funnel

3: Panel part

4: Stem

5: electron gun

7: deflection yoke

11: beam control electrode

14: focus electrode

16: phosphor screen

21: electrode support member

The color cathode ray tube of this invention achieves the said objective by the following typical structures.

That is, according to one embodiment of the present invention, a panel portion, a neck portion, and an opening end having a large diameter are coupled to the panel portion, and a funnel portion having a small diameter opening end coupled to the neck portion and a conductive pin are embedded. A vacuum external device comprising a stem for closing an opening end of the neck portion opposite to the funnel portion, a phosphor screen formed on an inner surface of the panel portion, an electron gun housed in the neck portion, transition of the neck portion and the funnel portion; In a cathode ray tube having a deflection yoke externally mounted near a region, the electron gun is made by arranging the cathode, the beam control electrode, the acceleration electrode, the first electrode, the focus electrode, and the anode in this order over a predetermined interval. The anode comprises a large diameter cylindrical portion on the phosphor screen side and a small diameter cylindrical portion on the cathode side in an axial direction, The focus electrode has a larger diameter cylindrical portion on the phosphor screen side having a larger diameter than the smaller diameter cylindrical portion of the anode, and a smaller diameter than the smaller diameter cylindrical portion of the anode. A cylindrical portion of a small diameter is axially coupled, a large diameter cylindrical portion of the focus electrode is disposed coaxially with this in the large diameter cylindrical portion of the anode, and the anode and the first electrode LG4 is electrically connected in the tube, and the length from the end face of the phosphor screen side of the focus electrode to LG4 (mm) and the distance from the end face of the phosphor screen side of the focus electrode to the center of the phosphor screen are LP (mm). Has a relationship with LP,

-LP + 184.9 ≥ LG4 ≥ 0.0004 LP 3 - 0.1571 LP 2 + 21.006 LP - 922.41,

LP ≥ 131.7

It is a cathode ray tube characterized by the above-mentioned.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail with reference to the Example shown.

The inventors have studied to realize the reduction of the overall length of the cathode ray tube for projection type TV by the cathode ray tube using the electron gun 5 schematically shown in FIG.

1 is a side view of a cathode ray tube according to an embodiment of the present invention, a part of which is shown in cross-sectional view.

A funnel portion 2 is connected to one end of the neck portion 1, and a panel portion 3 is connected to an opening end of the large diameter of the funnel portion 2, and a stem is connected to the other end of the neck portion 1. (4) is connected and forms the vacuum external apparatus.

In the neck portion 1 having an outer diameter of 29.1 mm, a single beam type electron gun 5 is accommodated. The electron gun 5 includes a heat radiation type cathode 10, a beam control electrode G1 11, an acceleration electrode G2 12, a third electrode G3 13, and a focus electrode G4. (14) and anodes (G5) (15) are arranged through a predetermined gap and are fixed by embedding the electrode support member (21) provided on the sidewall of each electrode in a pair of bead glass (22). have.

Predetermined voltage is applied to each electrode via the stem pin 9 embedded in the stem 4. In one typical operating condition, an average of about 190V at the cathode 10, a ground potential at the control electrodes G1, 11, 550-600V at the acceleration electrodes G2 12, and a third electrode G3 13 And a focus voltage (for example, about 7.7 kV) is applied to the anodes G5 and 15 at a maximum voltage of 30 kV and the focus electrodes G4 and 14.

The panel 3 has a lens function by adopting a structure in which the thickness is thickened at the center of the screen and thinned at the periphery. On the inner surface of the panel 3, a phosphor screen 16 having a diagonal diameter of about 5.5 inches (139.7 mm) is formed. The aluminum vapor deposition film 17 is formed on the electron gun side surface of the phosphor screen 16.

A positive electrode button 18 for applying a positive voltage is embedded in the funnel portion 2, and a built-in graphite film 19 and a positive electrode G5 in which the positive voltage applied to the positive electrode button 18 is applied to the inner surface of the funnel portion 2. It is applied to the third electrode (G3) 13 and the anode (G5) 15 via the valve spacer contact 20 fixed to the (). The anode voltage is also applied to the aluminum vapor deposition film 17.

The electron beam (not shown) emitted from the electron gun 5 is deflected by the deflection yoke 7 to scan the phosphor screen 16. In this embodiment, the deflection angle in the screen diagonal direction is 90 degrees. In this embodiment, the speed modulation coil 8 is provided for improving the image contrast.

The inventor knows the optimum value of the axial length LG4 of the focus electrode G4 14 which does not impair the focus characteristic even if the length of the electron gun 5 is shortened in the tube axis direction for the purpose of shortening the overall length of the cathode ray tube. In order to produce it, a computer simulation experiment described below was conducted.

Experimental conditions were set as follows.

Beam aperture of the beam control electrode (G1) 11 = 0.6 mm

Plate thickness of beam aperture of beam control electrode (G1) 11 = 0.08 mm

Beam aperture of accelerating electrode (G2) 12 = 0.6 mm

Plate thickness of beam aperture of acceleration electrode G2 12 = 0.39 mm

Beam aperture side of cathode 10 side of third electrode G3 (13) = 2.2 mm

Opening diameter of the anode G5 and the side of the third electrode G3 13 = 9.9 mm

Axial length LG3 of the third electrode G3 13 = 20.5 mm

Opening diameter DFS of the cathode 10 side of the focus electrode G4 14 = 9.9 mm

Opening diameter DFL of the anode G5 and 15 sides of the focus electrodes G4 and 14 = 15.8 mm

Aperture diameter DA of phosphor screen 16 side of anode G5 15 = 21.95 mm

Spacing between cathode 10 and beam control electrode G1 11 = 0.11 mm

Spacing between beam control electrode G1 11 and acceleration electrode G2 12 = 0.27 mm

Interval S23 between the acceleration electrode G2 12 and the third electrode G3 13 = 1.73 mm

Interval S34 between third electrode G3 13 and focus electrode G4 14 = 2.0 mm

Cathode 10 potential = adjusted to obtain its beam current per simulation condition

Beam control electrode (G1) 11 = ground potential

Acceleration electrode (G2) 12 potential = 600 V

Third electrode (G3) 13 potential = 30 kV

Focus electrode G4 (14) potential = adjusted to obtain optimum focus for each simulation condition

Positive (G5) (15) potential = 30 kV

As a parameter of the simulation,

(1) The distance LP from the end surface of the phosphor screen 16 side of the focus electrode G4 14 to the center of the phosphor screen 16 (hereinafter referred to as the phosphor surface distance LP).

(2) Set two types of axial lengths LG4 of the focus electrodes G4 and 14 (hereinafter referred to as focus electrode lengths LG4), and each combination of these two parameters is set to negative current 0.5 Evaluated with 5% beam spot diameter for mA, 2.0 mA, 6.0 mA. The 5% beam spot diameter refers to the beam spot diameter as the distance between the points of 5% of the peak value in the beam intensity distribution on the phosphor screen.

Further, the cathode current value is an evaluation condition in consideration of the multipurpose correspondence from the low current region for display monitor use to the high current region for TV use.

In Fig. 2, three cases of 142.4 mm, 137.4 mm, and 132.4 mm as the fluorescence plane distance LP were adopted, and three cases of 48.7 mm, 38.7 mm, and 28.7 mm were adopted as the focus electrode length LG4. Show the results. A plot of the simulation results of FIG. 2 is shown in FIG.

3 also plots the 5% beam spot diameter allowable upper limits of 0.193 mm, 0.182 mm and 0.343 mm for the cathode currents 0.5 mA, 2.0 mA and 6.0 mA, respectively, required for the cathode ray tube for the projection TV from the projection TV receiver side. .

In addition, these 5% beam spot diameter upper limit allow the same focusing performance as that of the large-diameter lens electron gun for the projection-type cathode ray tube (Projection CRT) mounted on a large projection TV with a screen having a diagonal size of 50 inches or more. It is a value to hold | maintain also in a receiver.

The total length of the projection cathode ray tube actually mounted with the large-diameter lens electron gun used in the large projection TV receiver is increased to 270 mm, so that the screen has a diagonal size of 40 inches (37 to 49 inches) for compact compact projection TV receivers. It is difficult to employ the large-diameter lens electron gun in the projection type cathode ray tube of.

The present invention reduces the overall length of the projection cathode ray tube while maintaining the focusing performance of the projection projection cathode ray tube corresponding to the large projection TV receiver, thereby providing a direct-view TV receiver having a maximum screen size of 36 inches and a large screen having a minimum screen size of 50 inches. The screen size as a product that compensates for the projection TV receiver is related to the cathode ray tube used in the 40-inch small projection TV receiver.

The specifications and focus characteristics of the projection type cathode ray tube corresponding to the large projection TV receiver are shown in Figs. 2 and 3 with a forming surface distance LP of 142.4 mm and a focus electrode length LG4 of 48.7 mm.

2 and 3, the beam spot diameters for the cathode currents of 0.5 mA, 2.0 mA and 6.0 mA in the electron gun with the fluorescent surface distance LP = 142.4 mm and the focus electrode length LG4 = 48.7 mm are 0.168. Mm, 0.158 mm, 0.298 mm.

The 5% beam spot diameter allowable upper limit of the cathode ray tube for a small projection TV receiver according to the present invention is increased by 15% of the 5% beam spot diameter allowable upper limit of the projection type cathode ray tube for a large projection TV receiver to 0.193 mm, 0.182 mm, 0.343 mm. did.

The reason for this 15% increase is that the focus characteristic on the screen of the projection-type TV receiver is substantially maintained even if the focus performance on the phosphor screen of the projection-type cathode ray tube varies by ± 15%. That is, if the variation in the beam spot diameter on the phosphor screen of the projection cathode ray tube is in the range of ± 15%, it does not affect the vividness of the image on the projection TV receiver screen as much. This is because a projection lens, a reflecting mirror, and a projection TV receiver screen lens are interposed between the projection cathode ray tube phosphor screen and the screen of the projection TV receiver.

In Fig. 3, the fluorescent surface distance LP is set to 142.4 mm, 137.4 mm, and 132.4 mm for the cathode currents of 0.5 mA, 2.0 mA, and 6.0 mA in order to satisfy the 5% beam spot diameter upper limit. In this case, it can be seen that the focus electrode length LG4 may be set to satisfy the following table.

Fluorescent surface distance LP (mm) Focus electrode length LG4 (mm)

132.4 33.2 or later

137.4 35.5 or more

142.4 38.2 or later

In other words, it can be seen that in order to set the 5% beam spot diameter to an upper limit or lower, the lower limit of the focus electrode length LG4 in the above table may be set for each of the fluorescent surface distances LP.

On the other hand, when the entire length of the projection cathode ray tube is fixed and the focus electrode length LG4 is increased, the anode G5 forming the main lens together with the opening of the phosphor screen 16 side of the focus electrode G4 14 is formed. (15) also needs to extend to the phosphor screen 16 side. However, as apparent from Fig. 1, when the tip of the anode G5 15 is excessively close to the deflection yoke 7, the deflection magnetic field from the deflection yoke 7 causes the polarization of the anode G5 15 to fail. Excessive overcurrent occurs in the electrode, causing a problem of heat generation.

In particular, recently, the projection type TV receiver has been operated at two or three times the horizontal deflection frequency of the conventional horizontal deflection frequency of 15.75 Hz. Therefore, this problem cannot be ignored.

In addition, if the entire length of the projection type cathode ray tube is fixed and the focus electrode length LG4 is excessively increased, the fluorescent surface distance LP becomes quite small. Then, the center of the main lens is too close to the deflection yoke 7, the main lens magnetic field is distorted by the deflection magnetic field, which may deteriorate the focus characteristic.

Therefore, the present inventors have obtained the lower limit of the fluorescent surface distance LP, which can avoid excessive heat generation or deterioration of focus characteristics due to overcurrent, and the lower limit of the focus electrode length LG4 summarized in the above table. The allowable ranges of the fluorescence surface distance LP and the focus electrode length LG4 are shown by the diagonal region in FIG.

Line a represents the lower limit of the focus electrode length LG4 (mm), and is represented by the following inequality approximation in the embodiment of the present invention.

[Equation 1]

^{LG4 ≥ 0.0004 LP 3 - 0.1571 LP} 2 + 21.006 LP - 922.41

By satisfying this expression (1), the 5% beam spot diameter becomes less than or equal to the lower limit, and the focus characteristic is improved.

Line b represents the lower limit of the fluorescent surface distance LP (mm), and is represented by the following inequality in the examples according to the present invention.

[Equation 2]

LP ≥ 131.7

By satisfying this expression (2), the influence of the deflection magnetic field can be reduced.

Line c represents an upper limit of the focus electrode length LG4 (mm), and is represented by the following inequality in the embodiment according to the present invention.

[Equation 3]

LG4 ≤ -LP + 184.9

By satisfying this expression (3), it is possible to realize a projection type TV receiver for a table top with a shorter overall length than a projection type cathode ray tube for a large projection TV receiver.

The line d represents a suitable upper limit of the focus electrode length LG4 (mm), and is represented by the following inequality in another embodiment according to the present invention.

[Equation 4]

LG4 ≤ -LP + 176.1

By satisfying this expression (4), the overall length of the projection cathode ray tube can be shortened to 255 mm or less, and it can correspond to a more compact small projection TV receiver.

If the relationship between the fluorescent surface distance LP and the focus electrode length LG4 is in the diagonal region surrounded by the lines a, b and c of Fig. 4, the focus characteristic required for the cathode ray tube for the projection TV from the projection TV receiver side is obtained. In addition, even in double speed (2 x 15.75 kHz) or triple speed (3 x 15.75 kHz) scanning operations, the problem of heat generation due to overcurrent can be avoided, and the miniaturization of the projection-type TV receiver can be realized.

Further, if the relationship between the fluorescent surface distance LP and the focus electrode length LG4 is in the oblique region surrounded by lines a, b, and d in Fig. 4, from the outer surface of the panel portion of the cathode ray tube for projection TV to the outer surface of the stem It is possible to make the distance of 255 mm or less.

In addition to the simulation and examination results described above, the inventors conducted various simulations and experimental zone test production to confirm the following points.

The present invention has a remarkable effect in preventing deterioration of focus characteristics when the total length of the electron gun is shortened when the outer diameter of the neck portion of the projection-type VT cathode ray tube is 29.1 mm or less.

When the effective diagonal diameter of the phosphor screen is about 139.7 mm, the present invention brings a remarkable effect on securing focus characteristics, and makes a great contribution to the miniaturization of the projection-type TV receiver.

In the present invention, when the inner diameter of the large diameter cylindrical portion of the anode is about 22 mm, the inner diameter of the large diameter cylindrical portion of the focus electrode is about 15.8 mm, and the inner diameter of the small diameter cylindrical portion of the focus electrode is about 9.9 mm, the outer diameter of the neck portion is 29.1 mm. It is possible to achieve the following, which enables the realization of a small projection TV receiver with low power consumption.

In the present invention, by setting the voltage applied to the focus electrode within the range of 25% to 28% of the voltage applied to the anode, deterioration of the focus characteristic can be sufficiently avoided even if the total length of the electron gun is shortened.

In addition, in the present invention, by setting the voltage applied to the anode to about 30 kV, deterioration of the focus characteristic can be sufficiently avoided even if the total length of the electron gun is shortened.

In addition, according to the present invention, the length in the tube axis direction of the “first electrode” disposed opposite to the cathode side of the focus electrode and to which the anode voltage is applied can be 20.5 mm or less, which also contributes greatly to shortening the overall length of the cathode ray tube. do.

As described above, in the typical configuration of the present invention, in order to shorten the overall length of the cathode ray tube, deterioration of the focus characteristic can be avoided when the fluorescent surface distance is shortened, and excessive heat due to overcurrent during high-speed scanning operation By optimizing the length of the focus electrode which can avoid the occurrence, the projection TV receiver using the cathode ray tube of the present invention enables miniaturization and high quality image display.

Claims (9)

A panel portion, a neck portion, and a large diameter opening end coupled to the panel portion, a funnel portion having a small diameter opening end coupled to the neck portion, and a conductive pin embedded therein, and closing the opening end portion of the neck portion opposite to the funnel portion. A vacuum casing consisting of a stem, A phosphor screen formed on the inner surface of the panel portion; An electron gun accommodated in the neck portion; In the cathode ray tube having a deflection yoke, which is externally disposed near the transition region of the neck portion and the funnel portion, The electron gun is made by arranging the cathode, the beam control electrode, the acceleration electrode, the first electrode, the focus electrode, and the anode in this order over a predetermined interval, The anode consists of a large diameter cylindrical portion on the phosphor screen side and a small diameter cylindrical portion on the cathode side are combined in a tube axis direction. The focus electrode includes a large diameter cylindrical portion on the side of the phosphor screen having a larger diameter than the small diameter cylindrical portion of the anode, and a small diameter cylindrical portion on the cathode side having a diameter smaller than that of the small diameter cylindrical portion of the anode in a tubular direction. The large diameter cylindrical portion of the focus electrode is disposed coaxially with the large diameter cylindrical portion of the anode, The anode and the first electrode are electrically connected in a tube; When the tube axis length of the focus electrode is LG4 (mm) and the distance from the end surface of the phosphor screen side of the focus electrode to the center of the phosphor screen is LP (mm), the relationship between LG4 and LP is -LP + 184.9 ≥ LG4 ≥ 0.0004 LP 3 - 0.1571 LP 2 + 21.006 LP - 922.41, LP ≥ 131.7 Cathode ray tube characterized in that. The cathode ray tube according to claim 1, wherein the LG4 and the LP satisfy -LP + 176.1? LG4. The cathode ray tube according to claim 1 or 2, wherein an outer diameter of the neck portion is 29.1 mm or less. The cathode ray tube according to any one of claims 1 to 3, wherein a distance from an outer surface of said panel portion to an outer surface of said stem is 255 mm or less. The cathode ray tube according to any one of claims 1 to 4, wherein the effective diagonal diameter of the phosphor screen is about 139.7 mm. The inner diameter of the large diameter cylindrical portion of the anode is about 22 mm, the inner diameter of the large diameter cylindrical portion of the focus electrode is about 15.8 mm, and the inner diameter of the small diameter cylindrical portion of the focus electrode. The cathode ray tube, which is about 9.9 mm. The cathode ray tube according to any one of claims 1 to 6, wherein the voltage applied to the focus electrode is in a range of 25% to 28% of the voltage applied to the anode. The cathode ray tube according to any one of claims 1 to 7, wherein the voltage applied to the anode is about 30 kV. The cathode ray tube according to any one of claims 1 to 8, wherein a length in the tube axis direction of the first electrode is 20.5 mm or less.