KR20010021412A - In-line type electron gun and color cathode-ray tube with the same - Google Patents

Abstract

PURPOSE: A color cathode-ray tube and an election gun thereof is provided to make uniform the shape of beam spot of three electron beams from the center of screen to the end parts left and right, without complicating the structure of an electron gun. CONSTITUTION: This color cathode-ray tube is equipped with converging auxiliary lenses formed by dividing a convergence electrode into a plurality of segments, and electrode part(3) constituting the auxiliary lenses includes three electron beam passing holes(21,22,23) laid in horizontal arrangement, where the holes(31,32,33) on the sides have the same diameter, and different from the diameter of the holes(21,22,23) in the center. Accordingly, the shape of beam spot of three electron beams is uniformed without complicating the structure of the electron gun.

Description

IN-LINE TYPE ELECTRON GUN AND COLOR CATHODE-RAY TUBE WITH THE SAME}

FIELD OF THE INVENTION The present invention relates to an inline electron gun and a color cathode ray tube (CRT) having the same, and more particularly to an inline electron gun and a color CRT equipped with the gun to provide a desired high resolution on an entire fluorescent screen.

In order to improve the resolution of the color CRT, it is necessary to reduce each size of the beam spot formed on the fluorescent screen by three electron beams for red (R), green (R), and blue (B) colors. In addition, it is necessary to focus these beam spots at any point on the entire fluorescent screen. If any of these do not match, the image quality of the image on the screen is degraded.

In a conventional color CRT, a so-called "inline and self-convergence system" has been commonly used and emits three electron beams for R, G, and B colors, and is self-converging, arranged on a flat surface Includes mold deflection magnetic field. This self-converged deflection magnetic field is formed by the combination of a horizontal deflection magnetic field 101 having a pincushion type distribution shown in FIG. 1A and a vertical deflection magnetic field 102 having a barrel type distribution shown in FIG. 1B. It is a nonuniform magnetic field. Thus, ideally, the R, G, B color electron beams 110R, 110G, 110B emitted from the electron gun automatically focus on any point on the fluorescent screen. Hereinafter, the three electron beams for the R, G, and B colors may be named simply R, G, and B electron beams, respectively.

The inline and self-convergence system described above is simple and easily adjustable in the construction of an electrical circuit for focusing the R, G, B electron beams 110R, 110G, 110B, and the beams 110R, 110G, 110B have high accuracy. Has the advantage of being able to focus on. However, the beams 110R, 110G, 110B passing through the self-converged deflection magnetic field are affected by the magnetic field distortions present in the horizontal and vertical deflection magnetic fields 101, 102. Thus, some distortion of the electron beam spot tends to occur in the peripheral region of the fluorescent screen.

Specifically, as shown in FIG. 2, when the R, G, B electron beams 110R, 110G, 110B are not deflected, they form a circular beam spot 114 in the center of the fluorescent screen 115. On the other hand, when the beams 110R, 110G, 110B are deflected toward the peripheral area of the screen 115, they are horizontally extended beam cores 111 and halo extending vertically from the cores 111. Form a distorted, non-linear beam spot 113 that includes 112. As a result, the beam spot 113 formed in the peripheral region is larger than the beam spot 114 formed in the center, which causes the resolution of the color CRT in the peripheral region of the screen 115 to be significantly reduced.

Detailed observation of the distortion of the beam spot 113 in the peripheral area of the screen 115 provided the following results.

In detail, the first focus voltage V _fh that minimizes the horizontal size of the spot 113 is different from the second focus voltage V _fv that minimizes the vertical size of the spot 113. First focus voltage difference ΔV V _fh and _f of the second focus voltage V _fv (i.e., ΔV = V _f -V _{fh fv)} is negative. This means that since the electron beams 110R, 110G, 110B are in an over-focus condition in the vertical direction, the halo 112 extends in the vertical direction. This is because the self-converged deflection magnetic field provides horizontal focusing force and horizontal diverging force to the R, G, and B beams 110R, 110G, and 110B.

In order to reduce the aforementioned beam spot distortion in the peripheral region of the fluorescent screen 115 caused by the characteristics of the self-converging deflection magnetic field, various improved techniques have been developed and disclosed.

For example, Japanese Unexamined Patent Publication No. 61-99249, published in May 1986, discloses an improved electron gun and is shown in FIG.

As shown in FIG. 3, the prior art electron beam 220 includes three cathodes for the R, G, and B colors, the control electrode 226, the initial acceleration electrode 227, the first focus electrode 221, and the second. Focus electrode 222 and final acceleration electrode 228.

The cathodes 225R, 225G, 225B are arranged at specific intervals along the horizontal line (ie, the X axis in FIG. 3). The set of cathodes 225R, 225G, 225B, control electrode 226, initial acceleration electrode 227, first focus electrode 221, second focus electrode 222 and final acceleration electrode 228 is a gun ( Along the central axis Z of FIG.

Each of the control electrode 226 and the initial acceleration electrode 227 formed of a solid rectangular plate has three circular through-holes for penetrating the R, G, and B beams shown in FIG. 3.

The first focus electrode 221 formed of a rectangular parallel pipe box of an empty space has three rectangular openings 223 through which R, G, and B electron beams pass. The opening 223 is formed on an end surface of the electrode 221 in contact with the second focus electrode 222. The opening 223 extends in the vertical direction (ie, the Y axis in FIG. 3) and is arranged horizontally along the X axis. In addition, the first focus electrode 221 has three circular openings to allow the R, G, and B beams to penetrate on the end face in contact with the initial acceleration electrode 227.

The second focus electrode 222 formed of a rectangular parallel pipe box of an empty space has a rectangular opening 224 through which the R, G, and B electrode beams pass. The opening 224 is formed on an end surface of the electrode 222 in contact with the first focus electrode 221. Unlike the opening 223, the opening 224 extends in the horizontal direction (ie, the X axis). In addition, the second focus electrode 222 has three circular openings that allow the R, G, and B beams to penetrate the end face in contact with the final acceleration electrode 228.

The final accelerating electrode 228, formed of a rectangular parallel pipe box of empty space, has three circular openings through which the R, G, and B electrode beams pass. An opening is formed on an end surface of the electrode 228 in contact with the second focus electrode 222. The end face of the final acceleration electrode 228 opposite the second focus electrode 232 is fully open.

A fixed focus voltage 232 having a fixed value V _f shown in FIG. 4 is applied to the first focus electrode 221. The dynamic focus voltage 231 that changes according to the waveform shown in FIG. 4 is applied to the second focus electrode 222. The dynamic focus voltage 231 changes to synchronize with the horizontal and vertical deflection signals and is set to be higher than the fixed focus voltage 232. Thus, three electrostatic quadrupole lenses (not shown) are formed in the space between opposing surfaces of the first and second focus electrodes 221, 222 corresponding to the three rectangular openings 223 of the electrode 221. . An example of the electrostatic quadrupole lens thus formed is schematically illustrated in FIG. 5.

In Fig. 5, reference numeral 241 denotes an electrostatic quadrupole lens. In the lens 241, the potential is positive with respect to the center of the lens 241 in the vertical direction and negative with respect to the center of the lens 241 in the horizontal direction. Accordingly, the lens 241 exerts a diverging force 243 in the vertical direction and a focusing force 244 in the horizontal direction on the electron beam 242 passing through the lens 241. Operation of the lens 241 eliminates distortion of the beam 242 caused by the self-converged deflection magnetic field. In addition, since the dynamic focus voltage 231 changes in synchronization with the deflection signal of the beam 242, the operation of the lens 241 changes in the same manner. Thus, the effect of lens 241 to remove distortion of beam 242 is optimized, providing a uniform, small beam spot on the entire fluorescent screen.

As described above, in the electron gun 220 of the prior art shown in FIG. 3, a combination of the first and second focus electrodes 221 and 222 is used, and at the same time, the first focus electrode 221 has a fixed value having a constant value Vf. While the applied focus voltage 232 is applied to the second focus electrode 222, the dynamic focus voltage 231 that is synchronized with the horizontal and vertical deflection signals is applied to the electrostatic quadrupole lens 241. . Therefore, the beam spot distortion due to the self-converged deflection magnetic field can be effectively eliminated.

Recently, the need to provide large screens, large deflection angles and flat screens for color CRTs is increasing. If the prior art electron gun 220 shown in FIG. 3 is used to meet this need, a problem arises that the spots of the R, G and B electron beams have different shapes from each other in the peripheral region of the fluorescent screen. This problem is caused by the following reasons.

In general, when R, G, and B electron beams pass through a self-converged deflection magnetic field, these beams are applied with a vertical focusing force and a horizontal divergence force having a different size than the deflecting residual field. Specifically, for example, if the R, G, and B beams are deflected to the right end of the fluorescent screen, the R beam penetrates an area where magnetic field nonuniformity is stronger than the area through which the G and B beams penetrate. R, G, and B are focused on one point. As a result, the distortion of the spot formed by the R beam is larger than the distortion of the spot formed by the G and B beams.

On the other hand, if the R, G and B beams are deflected toward the left end of the fluorescent screen, in contrast to the case described above, the B beam penetrates an area where magnetic field nonuniformity is stronger than that where the R and G beams penetrate, R, G, and B beams are focused on a point on the screen. As a result, the distortion of the spot formed by the B beam is larger than the distortion of the spot formed by the R and G beams.

Thus, the dynamic focus voltage for compensating astigmatism (ie beam spot distortion) between the R and B beams has different magnitudes in the left and right end regions of the screen.

FIG. 6 schematically shows the beam spot shape in the peripheral region of the fluorescent screen according to the prior art electron gun 220 shown in FIG. 3. 7 schematically shows the change in the optimized dynamic focus voltage as a function of the horizontal position along the gun 220.

Typically, the dynamic focus voltage is determined to optimize the shape of the spot generated by the centrally located G electron beam. However, in this case, as shown in Fig. 7, the voltage difference ΔV _DRG is generated between the optimal dynamic focus voltage V _DG for the G beam and the optimal dynamic focus voltage V _DR for the R beam at the right end of the fluorescent screen. On the other hand, at the left end of the fluorescent screen, the voltage difference ΔV _DBG is generated between the optimal dynamic focus voltage V _DG for the G beam and the optimal dynamic focus voltage V _DB for the B beam. Therefore, compensation of astigmatism between the R and B beams cannot be optimized.

Thus, as shown in FIG. 6, halo 251 is formed in each beam spot 250R generated by the R beam in the right end region 253a of the fluorescent screen 253, and at the same time halo 252 is screened. It is formed in each beam spot 250B generated by the B beam in the left end region 253b of 253. As a result, a problem arises in that the resolution decreases in the left and right regions 253a and 253b.

In particular, in recent color CRTs designed for displays that require higher resolution, larger deflection angles, and flatter screens, optimal dynamic focus voltage for centered G beams and optimal dynamics for R and B beams on each side. The difference between the focus voltages becomes large, further highlighting the above-mentioned problem.

For example, in the current 19 inch color CRT having a large deflection angle and designed for display, the dynamic focus voltage difference ΔV _DRG between the R and G beams and the dynamic focus voltage difference ΔV _DBG between the B and G beams are shown in FIG. 7. Likewise, it has a maximum of about 150V.

Another improved electron gun of this type is disclosed in Japanese Unexamined Patent Publication No. 10-21847 published in January 1998, which solves the above-mentioned problems. This enhanced gun includes a pair of additional dynamic electrostatic quadrupole lenses with opposing tripole lenses in addition to the dynamic electrostatic quadrupole lenses described above.

However, in the improved electron gun disclosed in Publication No. 10-21847, it is necessary to configure the electrode to form a pair of additional dynamic quadrupole lenses. Therefore, a problem arises in that the configuration of the electron gun becomes more complicated.

In addition, since two different dynamic focus voltages must be applied to the gun, additional voltage supply pins need to be provided to the CRT and an additional circuit to generate a dynamic focus voltage for a pair of additional dynamic capacitive quadrupole lenses requires a display. There is another problem that it is required for a driving device, namely a color CRT.

It is therefore an object of the present invention to provide an inline electron gun which makes the spot shape of the R, G, and B electron beams substantially uniform in the middle region of the fluorescent screen as well as in the left and right end regions, and a color CRT equipped with the gun. .

It is another object of the present invention to provide an inline electron gun which achieves the desired high resolution over the entire fluorescent screen.

It is a further object of the present invention to provide an inline electron gun which reduces the spot distortion of R and B electron beams located on each side of the G electron beam without complicated configuration, additional pins or additional circuitry.

The foregoing objects, along with other objects not specifically mentioned, will become apparent from the following description to those skilled in the art.

According to a first aspect of the invention, an inline electron gun comprising a three-pole vacuum tube for generating first, second and third electron beams and a main lens system for focusing the first, second and third electron beams, respectively This is provided.

The three-pole vacuum tube may include first, second and third cathodes arranged at a specific distance on the same line in a first direction, and the first, second and third cathodes at a specific distance in a second direction perpendicular to the first direction. Control electrodes disposed adjacent to each other, and initial acceleration electrodes disposed adjacent to the control electrodes at a specific distance in the second direction. The first and third cathodes are arranged on opposite sides of the second cathode.

The main lens system includes a first focus electrode, a second focus electrode, and a final acceleration electrode arranged in the second direction. The first focus electrode is disposed adjacent to a specific distance with respect to the initial acceleration electrode of the tripolar vacuum tube. The second focus electrode is disposed adjacent a specific distance with respect to the first focus electrode. The final accelerating electrode is disposed adjacent a certain distance with respect to the second focus electrode.

The first focus electrode has electrode members disposed at specific distances or intervals in the second direction. A first member of the electrode members is disposed adjacent to the initial acceleration electrode. The final member of the electrode members is disposed adjacent to the second focus electrode. The final member and the second focus electrode of the electrode members may include a first, second and third 4 for the first, second and third electron beams between the final member and the second focus electrode of the electrode members. It functions to form a bipolar lens.

Each of the electrode members of the first focus electrode has first, second and third through holes to allow the first, second and third electron beams to pass therethrough. The first and third through holes are identical in size to each other, while the second through holes are different in size from the first and third through holes.

A fixed focus voltage is applied to the final member of the electrode members of the first focus electrode while a dynamic focus voltage is applied to the second focus electrode, thereby allowing the final one of the electrode members of the first focus electrode to be applied. The first, second and third quadrupole lenses are formed between the member and the second focus electrode. The first, second and third quadrupole lenses have a lens action that varies with the difference between the fixed and dynamic focus voltages.

The dynamic focus voltage is applied to at least one of the electrode members of the first focus electrode except for the final member, so that the first, second, and third electron beams for the first, second, and third electron beams in the first focus electrode are applied. Second and third focus lenses are formed. The first, second and third focus lenses have a focusing force that varies with the difference between the fixed and dynamic focus voltages.

The focusing force of the first and third focus lenses is changed at a ratio different from that of the second focus lens according to a difference between the fixed and dynamic focus voltages.

In the inline electron gun according to the first aspect of the present invention, the first focus electrode of the main lens system has electrode members arranged at a specific distance or interval in the second direction. Of the electrode members disposed adjacent to the second focus electrode, the final member and the second focus electrode function to form first, second and third quadrupole lenses for the first, second and third electrode beams therebetween. do. The first to third quadrupole lenses are formed by applying a fixed focus voltage to a final member of the electrode members of the first focus electrode and applying a dynamic focus voltage to the second focus electrode.

In addition, each of the electrode members of the first focus electrode has first, second and third through holes through which the first, second and third electron beams pass. Since the first and third cathodes are disposed on the opposite side of the second cathode, the first and third electron beams are disposed on the opposite side of the second electron beam.

Meanwhile, a dynamic focus voltage is applied to at least one of the electrode members of the first focus electrode except for the final member, so that the first, second and third electrode beams for the first, second and third electrode beams are applied to the first focus electrode. Three focus lenses are formed. The first, second and third focus lenses thus formed function as focus sub lenses in the main lens system.

Since the first and third through holes of each of the electrode members of the first focus electrode are identical in size to each other, but the second through hole is different in size from the first and third through holes, the first and third focus holes The focusing forces of the lenses are identical in size to each other, and differ in size from the focusing forces of the second focus lens.

In addition, the focusing force of the first, second and third focus lenses changes according to the difference between the fixed and dynamic focus voltages. The focusing force of the first and second focus lenses changes at a different rate from the focusing force of the second focus lens according to the difference between the fixed and dynamic focus voltages. Thus, the displacement of the image point of the first and third electron beams (ie, side electron beams), which is generated in accordance with the change of the dynamic focus voltage, differs in size from the image point of the second electron beam (ie, the central electron beam). Do. This means that the optimum value of the dynamic focus voltage for the center and side electron beams can be controlled separately. Therefore, the unbalance of the optimum value of the dynamic focus voltage between the center electron beam and the side electron beam can be suppressed.

Therefore, since the distortion of the spots formed by the side (i.e., the first and third) electron beams can be reduced, the spot shape of the three beams generated by the first, second and third electron beams is reduced to the fluorescent screen. In the middle region of, of course, it can be formed substantially uniformly in the left and right end regions. This means that the desired high resolution can be achieved on the entire fluorescent screen.

In addition, unlike the electron gun of the prior art disclosed in Japanese Unexamined Patent Publication No. 10-21847, no complicated configuration, additional pins, or additional circuits are required.

In a preferred embodiment of the electron gun according to the first aspect of the invention, the first and third through holes of each of the electrode members of the first focus electrode are smaller in size than the second through hole. The fixed focus voltage is set to be smaller in magnitude than the dynamic focus voltage.

In another preferred embodiment of the electron gun according to the first aspect of the present invention, the first and third through holes of each of the electrode members of the first focus electrode are larger in size than the second through hole. The fixed focus voltage is set so that the dynamic focus voltage is also smaller in size.

In another preferred embodiment of the electron gun according to the first aspect of the present invention, the number of electrode members of the first focus electrode is three, and the third member of the electrode members functions as the final member. The second member of the electrode members is disposed at a specific distance between the first and third members of the electrode members. A fixed focus voltage is applied to the first and third members of the electrode members, while a dynamic focus voltage is applied to the second member of the electrode members.

In a more preferred embodiment of the electron gun according to the first aspect of the present invention, the number of electrode members of the first focus electrode is two, of which the second member functions as a final member. A fixed focus voltage is applied to the first member of the electrode members while a dynamic focus voltage is applied to the second member of the electrode members.

According to a second aspect of the invention, there is provided a color CRT consisting of an inline electron gun according to the first aspect of the invention.

1A and 1B are schematic cross-sectional views illustrating the distribution of conventional horizontal and vertical deflection magnetic fields formed by conventional self-converged deflection yokes, respectively.

2 is a schematic diagram showing the shape of a spot formed on a fluorescent screen by R, G, and B electron beams deflected by a conventional self-converged deflection yoke.

Fig. 3 is a schematic perspective view showing the construction of the main part of the inline electron gun of the prior art.

FIG. 4 is a waveform diagram illustrating instantaneous changes in a fixed focus voltage and a dynamo focus voltage applied to the tank gun of the prior art shown in FIG.

FIG. 5 is a schematic cross-sectional view showing a state of a force applied to an electron gun from an electrostatic quadrupole lens formed by the electron gun of the prior art shown in FIG.

FIG. 6 is a schematic diagram showing the shape of a spot formed on a fluorescent screen by R, G and B electron beams in the prior art electron gun shown in FIG.

FIG. 7 is a graph showing the relationship between the optimal dynamic focus voltage in the prior art electron gun shown in FIG. 3 and the beam spot position on the fluorescent screen. FIG.

Fig. 8 is a schematic perspective view showing the configuration of main parts of the inline electron gun according to the first embodiment of the present invention.

FIG. 9 is a schematic perspective view illustrating a configuration of a first focus electrode of the electron gun according to the first embodiment of FIG. 8.

FIG. 10 is a schematic diagram illustrating through holes formed in each electrode member of the first focus electrode of the electron gun according to the first embodiment of FIG. 8, through which R, G, and B beams pass, wherein the through holes are formed in a first manner. Used to form the focus sub lens on the focus electrode.

FIG. 11 is a schematic cross-sectional view illustrating a structure in which dynamic and fixed focus voltages are applied to each electrode of the electron gun according to the first embodiment of FIG. 8; FIG.

FIG. 12 is a waveform diagram illustrating instantaneous changes in dynamic and fixed focus voltages applied to the electron gun according to the first embodiment of FIG. 8; FIG.

FIG. 13 is a graph showing the relationship between the optimal dynamic focus voltage in the electron gun and the beam spot position on the fluorescent screen according to the first embodiment of FIG.

FIG. 14 is a schematic diagram showing the shape of a spot formed on a fluorescent screen by R, G and B electron beams of the electron gun according to the first embodiment of FIG. 8; FIG.

Fig. 15 is a schematic perspective view showing the configuration of a first focus electrode used in an inline electron gun according to a second embodiment of the present invention.

FIG. 16 is a schematic diagram illustrating through holes formed in each electrode member of the first focus electrode of the electron gun according to the second embodiment of FIG. 15, through which the R, G, and B beams pass, wherein the through holes are formed in the first embodiment. Used to form the focus sub lens on the focus electrode.

FIG. 17 is a waveform diagram illustrating instantaneous changes in dynamic and fixed focus voltages applied to the electron gun according to the second embodiment of FIG. 15; FIG.

Fig. 18 is a schematic perspective view showing the configuration of main parts of the inline electron gun according to the third embodiment of the present invention.

FIG. 19 is a schematic cross-sectional view illustrating a structure in which dynamic and fixed focus voltages are applied to respective electrodes of the electron gun according to the third embodiment of FIG. 18; FIG.

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

1R, 1G, 1B: Cathodes for R, G, and B Colors

2: control electrode

3: initial acceleration electrode

4: first focus electrode

5: second focus electrode

6: final acceleration electrode

10: electron gun

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

8, 9, 10 and 11 show an inline electron gun 10 according to a first embodiment of the present invention.

As shown in FIG. 8, the electron gun 10 includes three cathodes 1R, 1G, 1B for R, G, and B colors, a control electrode 2, an initial acceleration electrode 3, and a first focus electrode ( 4), the second focus electrode 5 and the final acceleration electrode 6. The set of cathodes 1R, 1G, 1B, control electrode 2, initial acceleration electrode 3, first focus electrode 4, second focus electrode 5, and final acceleration electrode 6 are total It is arranged along the central axis Z of (10).

As shown in FIG. 8, the X axis is defined to be horizontal and perpendicular to the Z axis, and the Y axis is defined to be orthogonal and perpendicular to the Z and X axes.

The three cathodes 1R, 1G and 1B are arranged horizontally at equal intervals along the X-axis line. The cathodes IR, 1G and 1B have emission surfaces from which the R, G and B electron beams are respectively emitted. These emitting surfaces are perpendicular to the Z axis.

The control electrodes 2 formed of solid rectangular plates are arranged at specific intervals in the vicinity of the vicinity of the emission surfaces of the cathodes 1R, 1G and 1B. The control electrode 2 has three circular through holes 21, 22, 23 which allow R, G, and B beams to penetrate. These through holes 21, 22, and 23 are arranged at equal intervals along the X axis so as to be arranged at the centers of the emission surfaces of the cathodes 1R, 1G, and 1B, respectively.

The initial acceleration electrode 3 is formed of a solid rectangular plate and is similar to the control electrode 2. The electrodes 3 are arranged at specific intervals adjacent to the control electrodes 2 on opposite sides of the cathodes 1R, 1G and 1B. The electrode 3 has three circular through holes 31, 32, 33 which allow R, G, and B beams to penetrate. These through holes 31, 32, 33 are arranged at equal intervals along the X axis so as to be arranged at the centers of the through holes 21, 22, 23 of the control electrode 2, respectively.

As can be seen from FIGS. 8 and 9, the first focus electrode 4 has three electrode members 4a, 4b and 4c. Each of the two electrode members 4a, 4b and 4c is formed of a rectangular parallel pipe box of empty space. The electrode member 4b is formed of a solid rectangular plate.

The electrode members 4a are arranged at specific intervals in the vicinity of the initial acceleration electrode 3. The member 4a has three circular devices 4a4, 4a5 and 4a6 on the opposite surface of the initial acceleration electrode 3. The openings 4a4, 4a5 and 4a6 are arranged on the same line along the X axis and are disposed at the centers of the through holes 31, 32, 33 of the initial acceleration electrode 3, respectively. The openings 4a4, 4a5 and 4a6 are equal in size or diameter to each other.

In addition, the electrode member 4a has three circular openings 4a1, 4a2, 4a3 on opposite surfaces of the second electrode member 4b. The openings 4a1, 4a2 and 4a3 are arranged in the same line along the X axis and arranged in the center of the openings 4a4, 4a5 and 4a6, respectively. As shown in Fig. 10, the openings 4a1 and 4a3 arranged on each side have the same diameter of D1. The opening 4a2 arranged in the center has a diameter of D2 larger than the diameter D1 (that is, D2 &gt; D1).

The R, G, and B electron beams enter the interior of the first electrode member 4a by the openings 4a4, 4a5, and 4a6, and then open the member 4a by the openings 4a1, 4a2, 4a3, respectively. Escape It can be said that each of the openings 4a4, 4a5, 4a6 and the corresponding one of the openings 4a1, 4a2, 4a3 form a through hole for penetrating the corresponding ones of the 1B, 1G and 1R beams.

The electrode members 4b of the first focus electrode 4 are arranged at specific intervals in the vicinity of the electrode member 4a. The member 4b has three circular through holes 4b1, 4b2, 4b3 to allow the B, G and R beams to penetrate. The through holes 4b1, 4b2, 4b3 are arranged in the same line along the X axis so as to be arranged at the centers of the openings 4a1, 4a2, 4a3 of the electrode member 4a, respectively. As shown in Fig. 10, the through holes 4b1 and 4b3 disposed on each side have the same diameter of D1. The through hole 4b2 disposed at the center has a diameter of D2.

The electrode members 4c are arranged at specific intervals in the vicinity of the electrode member 4b. The member 4c has three circular openings 4c4, 4c5, 4c6 on the opposite surface of the member 4b. The openings 4c4, 4c5, 4c6 are arranged collinearly along the X axis so as to be arranged at the center of the through holes 4b1, 4b2, 4b3 of the member 4b. As shown in Fig. 10, the openings 4c4 and 4c6 disposed on each side have the same diameter of D1. The centrally located opening 4b2 has a diameter of D2.

In addition, the third electrode member 4c has three rectangular openings 4c1, 4c2, 4c3 on the opposing surface of the second focus electrode 5. These openings 4c1, 4c2 and 4c3 are arranged in the same line along the X axis so as to be arranged in the center of the openings 4c4, 4c5 and 4c6 respectively. The openings 4c1, 4c2, 4c3 extend along the Y axis and have the same length and width.

The B, G, and R electron beams enter the inside of the electrode member 4c by the openings 4c4, 4c5, and 4c6, and then exit the member 4c through the openings 4c1, 4c2, 4c3, respectively. It can be said that each of the openings 4c4, 4c5, 4c6 and the corresponding one of the openings 4c1, 4c2, 4c3 form a through hole for penetrating the corresponding ones of the 1B, 1G and 1R beams.

The second focus electrodes 5 formed of the rectangular parallel pipe boxes of the empty spaces are arranged at specific intervals in the vicinity of the electrode member 4c of the first focus electrode 4. As shown in FIG. 8, the second focus electrode 5 has three rectangular openings 51, 52, 53 on the opposite surface of the electrode member 4c of the first focus electrode 4. Unlike the openings 4c1, 4c2, 4c3 of the third electrode member 4c, the openings 1, 52, 53 extending along the X axis have the same length and width. The openings 51, 52, 53 are arranged in the same line so as to be arranged in the center of the openings 4c1, 4c2, 4c3, respectively.

The second focus electrode 5 also has three circular openings 54, 55, 56 on opposite surfaces of the final acceleration electrode 6. The openings 54, 55, 56 are arranged in the same line so as to be arranged at the center of the openings 51, 52, 53, respectively. The openings 54, 55, 56 are the same in diameter.

The B, G, and R electron beams enter the interior of the second focus electrode 5 by openings 51, 52, 53 and then exit the electrode 5 through the openings 54, 55, 56, respectively. . It can be said that each of the openings 51, 52, 53 and the corresponding one of the openings 54, 55, 56 forms a through hole for penetrating the corresponding ones of the 1B, 1G and 1R beams.

The final acceleration electrodes 6 formed of the rectangular parallel pipe boxes of the empty spaces are arranged at specific intervals in the vicinity of the second focus electrodes 5. As shown in FIG. 8, the final acceleration electrode 6 has three circular openings 61, 62, 63 on the opposite surface of the second focus electrode 5. These openings 61, 62, 63 are arranged collinearly along the X axis. The opening 62 disposed at the center is arranged at the center of the opening 55 of the second focus electrode 5. The openings 61, 63 arranged at each side are shifted outward along the X axis with respect to the center of the openings 54, 56 of the electrode 5.

The side of the final acceleration electrode 6 opposite the second focus electrode 5 is fully open. Therefore, the R, G and B beams entering the inside of the electrode 6 can freely exit the electrode 6.

The three cathodes 1R, 1G and 1B, the control electrode 2, and the initial acceleration electrode 3 are "triodes" (in other words, electrons) that generate R, G and B electron beams and emit the same outwards. Beam forming region "). The first and second focus electrodes 4, 5 and the final acceleration electrode 6 constitute a “main lens system” for focusing the R, G, B beams emitted from the tripolar vacuum tube on a fluorescent screen.

In the electron gun 10 according to the first embodiment of the present invention, as shown in FIG. 11, the fixed focus voltage E _C3S is commonly applied to the electrode members 4a and 4c of the first focus electrode 4. . The dynamic focus voltage E _C3D which changes in synchronization with the deflection signal is commonly applied to the electrode member 4b of the first focus electrode 4 and the second focus electrode 5. Furthermore, the anode voltage E _b is applied to the final accelerating electrode 6.

The magnitudes of the fixed and dynamic focus voltages E _C3S and E _C3D are determined to satisfy the following equation (1).

Specifically, the fixed and dynamic focus voltages E _C3S and E _C3D have waveforms as shown in FIG. 12. The fixed focus voltage E _C3S has a fixed magnitude. The dynamic focus voltage E _C3D has a parabolic waveform that will be minimal when the electron beam is not deflected (in other words, when the deflection angle of the beams is set to "0"), and the voltage value increases with increasing deflection angle.

The electron gun 10 having the above-described configuration operates in the following manner.

As shown in FIG. 11, three rotationally symmetrical focus sub lenses SL1, SL2 and SL3 are formed between the electrode members 4a and 4c of the first focus electrode 4. The focus sub lens SL1 is formed at a position corresponding to the openings 4a3 and 4a6 of the electrode members 4a and 4c and the through hole 4b3 of the electrode member 4b. The focus sub lens SL2 is formed at a position corresponding to the openings 4a2 and 4a5 of the electrode members 4a and 4c and the through hole 4b2 of the electrode member 4b. The focus sub lens SL3 is formed at a position corresponding to the openings 4a1 and 4a4 of the electrode members 4a and 4c and the through hole 4b1 of the electrode member 4b.

In addition, three electrostatic quadrupole lenses QL1, QL2, and QL3 are formed between the first focus electrode 4 and the second focus electrode 5. The quadrupole lens QL1 is formed at a position corresponding to the openings 4c3 and 53 of the electrode member 4c and the second focus electrode 5. The quadrupole lens QL2 is formed at a position corresponding to the openings 4c2 and 52 of the electrode member 4c and the second focus electrode 5. The quadrupole lens QL3 is formed at a position corresponding to the openings 4c1 and 51 of the electrode member 4c and the second focus electrode 5.

In addition, three rotationally symmetrical focus main lenses ML1, ML2, ML3 are formed between the second focus lens 5 and the final acceleration electrode 6. The focus main lens ML1 is formed at a position corresponding to the openings 56, 63 of the second focus electrode 5 and the final acceleration electrode 6. The focus main lens ML2 is formed at a position corresponding to the openings 55, 62 of the second focus electrode 5 and the final acceleration electrode 6. The focus main lens ML3 is formed at a position corresponding to the openings 54, 61 of the second focus electrode 5 and the final acceleration electrode 6.

In Fig. 11, reference numerals EB1, EB2, EB3 refer to R, G, B electron beams, respectively. The electron beams EB1, EB2, EB3 emitted and formed from the cathodes 1R, 1G, 1B of the tripolar vacuum tube are focused by the focus sublenses SL1, SL2, SL3, respectively, and then enter the quadrupole lenses QL1, QL2, QL3, respectively. When the beams EB1, EB2, EB3 pass through the quadrupole lenses QL1, QL2, QL3, a quadrupole lens operation is applied which compares the astigmatism of the beams EB1, EB2, EB3 induced by the self-converged deflection magnetic field. The beams EB1, EB2, EB3 are then finally focused by the focus main lenses ML1, ML2, ML3, which are then emitted from the electron gun 10 toward the fluorescent screen.

The R, G, B electron beams EB1, EB2, EB3 emitted from the gun 10 are deflected by a self-converged deflection magnetic field generated by a deflection yoke (not shown). Next, by beams EB1, EB2, EB3 hitting a specific position of a fluorescent screen (not shown), an image is displayed on the screen.

As shown in FIG. 12, the difference between the fixed and dynamic focus voltages E _C3S and E _C3D has a maximum magnitude when the dynamic focus voltage E _C3D is minimum, and the difference has a minimum magnitude when the E _C3D voltage is maximum. In other words, the fixed and dynamic focus voltages E _C3S and E _C3D have their maximum magnitude when the deflection angle is "0" and decrease as the deflection angle increases.

The focusing force applied to the electron beams EB1, EB2, EB3 by the focus sub-lenses SL1, SL2, SL3 respectively varies with the difference between the fixed and dynamic focus voltages E _C3S and E _C3D . Therefore, the focusing forces by the sub lenses SL1, SL2, SL3 become maximum at the deflection angle of "0" and they decrease as the deflection angle increases. This means that the image points formed by the main lens system are shifted from the gun 10 along the Z axis, ie they are under-focused.

As described above, in the electrode members 4a, 4b, 4c of the first focus electrode 4, the openings 4a2, 4a5 and the through hole 4b2 arranged in the center have the same diameter D2. On the other hand, the openings 4a1, 4a3, 4c4, 4c6 and the through holes 4b1, 4b3 arranged on each side of the openings 4a2, 4c5 and the through holes 4b2, respectively, have the same diameter D1 smaller than D2. . Therefore, the focusing force (ie, lens operation) of the sub lenses SL1 and SL3 is larger than that of the sub lens SL2.

Since the main lens system comprises the focusing sub-lenses SL1, SL2, SL3 described above, the R and B beams EB1, EB3 (i.e., side beam) due to the change in the difference between the fixed and dynamic focus voltages E _C3S and E _C3D The image point shift amount is larger than the G beam EB2 (ie, center or intermediate beam). In other words, the side beams EB1, EB3 are _underfocused more strongly than the center beam EB2 as the dynamic focus voltage E _C3D increases (ie, the deflection angle increases). Thus, the value of the dynamic focus voltage E _C3D requiring the side beams EB1 and EB3 (ie, the optimal dynamic focus voltage) can be lower than that requiring the center beam EB2.

FIG. 13 shows the relationship between the beam spot position on the fluorescent screen and the optimum dynamic focus voltage in the electron gun 10 according to the first embodiment of FIG. 8.

As can be clearly seen from the comparison between Fig. 7 and Fig. 13, in the electron gun 10 according to the first embodiment, the optimum dynamic focus voltage V _DG for the G beam EB2 from the right etch of the fluorescent screen is optimized for the R beam EB1. The difference ΔV _DRG (ie, ΔV _DRG = V _DR −V _DG ) of the dynamic focus voltage V _DR is reduced compared to the conventional electron gun 220 shown in FIG. 3. Also, at the left edge of the fluorescent screen, the difference ΔV _DBG (ie, ΔV _DBG = V _DB -V _DG ) between the optimal dynamic focus voltage V _DG for G beam EB2 and the optimal dynamic focus voltage V _DB for B beam EB3 is known. Compared with the electron gun 220. Thus, the imbalance among the optimal dynamic focus voltages V _DR , V _DG , V _DB for the R, G, B beams EB1, EB2, EB3 can be suppressed.

Fig. 14 shows the shape of the spot formed on the fluorescent screen by the R, G, B electron beams EB1, EB2, EB3 in the electron gun 10 according to the first embodiment.

As can be clearly seen from FIGS. 14 and 16, in the electron gun 10 according to the first embodiment, each halo 91 of the spot 90R generated by the R beam EB1 is the right side of the fluorescent screen 93. The tip region 93a is smaller in size than the conventional gun 220. In addition, each halo 92 of the spot 90B generated by the B beam EB3 is smaller in size than the conventional gun 220 in the left end region 93b of the screen 93. Thus, the resolution in the left and right end regions 90a and 90b of the screen 90 can be improved.

As described in detail, in the in-line electron gun 10 according to the first embodiment of the present invention, the main lens system includes first and second focus electrodes 4 and 5 and a final acceleration electrode 6, The first focus electrode 4 has three electrode members 4a, 4b and 4c. The fixed focus voltage E _C3S is applied to the two electrode members 4a and 4c, and at the same time, the dynamic focus voltage E _C3D is applied to the electrode member 4b and the second focus electrode 4. Thus, three focus sub-lenses SL1, SL2 and SL3 are formed between the electrode members 4a and 4c, and the three electrostatic quadrupole lenses QL1, QL2 and QL3 are the electrode member 4c and the second focus electrode. It is formed between (5) and three focus main lenses ML1, ML2 and ML3 are formed between the second focus electrode 5 and the final acceleration electrode 6.

The electrode members 4a and 4c of the first focus electrode 4 have openings 4a2 and 4a5 arranged in the center and the electrode member 4b has a through hole 4b2 in the center. The openings 4a2 and 4c5 and the through hole 4b2 have the same diameter of D1. In addition, the electrode members 4a and 4c have openings 4a1, 4a3, 4c4 and 4c6 arranged at each side and the electrode member 4b has through holes 4b1 and 4b3 at each side. The openings 4a1, 4a3, 4c4, 4c6 and the through holes 4b1, 4b3 have a diameter of the same D2 smaller than D1.

Accordingly, the focusing force of the focus sub-lenses SL1 and SL3 corresponding to the openings 4a1, 4a3, 4c4 and 4c6 and the through holes 4b1 and 4b3 corresponds to the openings 4a2 and 4c5 and the through hole 4b2. It is stronger than the focus sub lens SL2. The image point shift amount of the R and B beams EB1 and EB3 (side beams) due to the change in the difference between the fixed and dynamic focus voltages E _C3S and E _C3D is larger than the G beam EB2 (ie, the center beam). As a result, the unbalance of the optimum dynamic focus voltage generated between the center beam EB2 and the side beams EB1, EB3 can be suppressed.

Therefore, the distortion of the spot formed on the fluorescent screen 93 by the side beams EB1, EB3 can be reduced. Thus, the spot shape of the R, G, B beams EB1, EB2 and EB3 can be formed substantially uniformly in the middle region of the screen 93 as well as the left and right end regions 93a and 93b. This allows to implement the desired high resolution on the entire screen 93.

Moreover, unlike the conventional electron gun disclosed in Japanese Unexamined Patent Publication No. Hei 10-21847, no complicated configuration, no additional pins, or additional circuits are required.

Second embodiment

15 and 16 show a first focus electrode 4 ′ used in an inline electron gun according to a second embodiment of the present invention.

Although not shown, the electron gun according to the second embodiment of the present invention has the exception that the diameters of the openings and through holes for forming the focus sub-lenses SL1, Sl2, SL3 are changed in the first focus electrode 4 '. The configuration is the same as that of the electron gun 10 according to the first embodiment of the eighth embodiment. Therefore, the description of the same configuration is omitted by adding the same reference numerals to the same components in FIG. 15 for the sake of simplicity.

As shown in FIG. 15, the first focus electrode 4 ′ has three electrode members 4a ′, 4b ′, and 4c ′. Like the first focus electrode 4 in the first embodiment, each of the two members 4a 'and 4c' is formed of an empty rectangular parallel pipe box, while the member 4b 'is made of solid. It is formed by a square plate.

The electrode member 4a 'has three circular openings 4a1', 4a2 ', 4a3' on the opposite surface of the electrode member 4b '. The openings 4a1 ', 4a2', 4a3 'are arranged collinearly along the X axis so as to be arranged in the center of the openings 4a4, 4a5, 4a6 of the same member 4a', respectively. As shown in Fig. 16, the openings 4a1 'and 4a3' arranged at each side have the same diameter of D1 ', while the opening 4a2' arranged at the center has a diameter D2 'smaller than D1'. (Ie, D1 '> D2').

After the R, G, and B electron beams EB1, EB2, EB3 enter the interior of the electrode member 4a 'through the openings 4a4, 4a5, 4a6, the openings 4a1', 4a2 ', 4a3', respectively. Through the member 4a '.

The electrode member 4b 'is disposed at a specific distance in the vicinity of the electrode member 4a'. The electrode member 4b 'has three circular through holes 4b1', 4b2 ', 4b3' through which the R, G, and B beams EB1, EB2, EB3 pass. These through holes 4b1 ', 4b2', and 4b3 'are arranged in the same line along the X axis so as to be arranged at the centers of the openings 4a1', 4a2 ', and 4a3' of the electrode member 4a ', respectively. As shown in Fig. 16, the through holes 4b1 'and 4b2' arranged at each side have the same diameter of D1 ', while the through holes 4b2' arranged at the center have a diameter of D2 '.

The electrode member 4c 'is disposed at a specific distance in the vicinity of the electrode member 4b'. The electrode member 4c 'has three circular openings 4c4', 4c5 'and 4c6' on the opposite surface of the electrode member 4b '. The openings 4c4 ', 4c5' and 4c6 'are arranged collinearly along the X axis so as to be arranged along the centers of the through holes 4b1', 4b2 'and 4b3' of the electrode member 4b ', respectively. As shown in Fig. 16, the openings 4c4 'and 4c6' arranged at each side have the same diameter of D1 ', while the opening 4b2' arranged at the center has a diameter of D2 '.

Further, the electrode member 4c 'has three rectangular openings 4c1, 4c2, 4c3 on the opposite surface of the second focus electrode 5', which is the same as the electron gun 10 according to the first embodiment.

The R, G, B electron beams EB1, EB2, EB3 enter the inside of the electrode member 4c 'through the openings 4c4', 4c5 ', 4c6', and then the openings 4c1, 4c2, 4c3, respectively. Through the member 4c '.

In the inline type electron gun according to the second embodiment of FIG. 15, unlike the electron gun 10 according to the first embodiment, the fixed focus voltage E _C3S is applied to the electrode members 4a ′, of the first focus electrode 4 ′. 4c '). The dynamic focus voltage E _C3D which changes in synchronization with the deflection signal is applied to the electrode member 4b '.

However, unlike the electron gun 10 according to the first embodiment, the fixed and dynamic focus voltages E _C3S and E _C3D are determined to satisfy the following equation (2).

Specifically, the fixed and dynamic focus voltages E _C3S and E _C3D have waveforms as shown in FIG. 17. The fixed focus voltage E _C3S has a fixed magnitude. The dynamic focus voltage E _C3D has a parabolic waveform that is minimal when the electron beam is not deflected (in other words, when the deflection angle of the beams is set to "0"), and the voltage value increases with increasing deflection angle.

In this case, as shown in FIG. 17, the difference between the fixed and dynamic focus voltages E _C3S and E _C3D has a minimum magnitude when the dynamic focus voltage E _C3D is minimum, and the difference has a maximum magnitude when the E _C3D voltage is maximum. In other words, the difference has a maximum magnitude when the deflection angle is "0" and decreases as the deflection angle increases.

Therefore, in the electron gun according to the second embodiment of the present invention, the focusing force applied to the electron beams EB1, Eb2, and EB3 by the focus sublenses SL1, SL2, SL3, respectively, is the difference between the fixed and dynamic focus voltages E _C3S and E _C3D . Will change accordingly. Therefore, focusing forces by the sub lenses EB1, EB2, EB3 are minimized at the deflection angle of " 0 " and they increase with increasing deflection angle. This means that the image points formed by the main lens system are shifted towards the gun 10, ie over-focused.

On the other hand, as the dynamic focus voltage E _C3D increases, the difference between the anode voltage Eb and the dynamic focus voltage E _C3D decreases, and as a result, the focusing power of the focus main lenses ML1, ML2, and ML3 is weakened. This means that the image points formed by the main lens system are shifted towards the gun, i.e. under-focused.

As described above, the increase in the dynamic focus voltage E _C3D represents an adverse effect on the setting of the focus sub lenses SL1, SL2, SL3 and the set of focus main lenses ML1, ML2, ML3, respectively. However, since the action on the main lenses ML1, ML2, ML3 is stronger than the action of the sub lenses SL1, SL2, SL3, the image points of the main lens system are shifted outward from the gun as the dynamic focus voltage E _C3D increases. That is, under-focused. The sub lenses SL1, SL2, SL3 weaken the under focusing operation of the main lens system, i.e. suppress the shift of the image point in the main lens system.

As described above, in the three electrode members 4a ', 4b', 4c 'of the first focus electrode 4', the centrally arranged openings 4a2 ', 4c5' and the through hole 4b2 ' ) Have the same diameter D2 '. On the other hand, the openings 4a1 ', 4a3', 4c4 ', 4c6' and the through holes 4b1 '. 4b3' respectively arranged at each side of the openings 4a2 ', 4c5' and the through holes 4b2 '. Has the same diameter of D1 'greater than D2'. Therefore, the focusing force (ie, lens action) of the sub lenses SL1 and SL3 is smaller than that of the sub lens SL2. Therefore, the operation for suppressing the image point shift by the sub lens SL2 in the main lens system is stronger than the operation by the sub lenses SL1 and SL3.

Since the main lens system includes the aforementioned focus sub-lenses SL1, SL2, SL3, the image of the R and B beams EB1, EB3 (i.e., side beams) due to the change of the difference between the fixed and dynamic focus voltages E _C3S and E _C3D . The point shift amount is larger than the G beam EB2 (ie, center or intermediate beam). In other words, the side beams EB1, EB3 are under-focused more strongly than the center beam EB2 with an increase in the dynamic focus voltage E _C3D (ie, an increase in the deflection angle). Thus, the value of the dynamic focus voltage E _C3D requiring the side beams EB1, EB3 (ie, the optimal dynamic focus voltage) can be lower than that requiring the center beam EB2. As a result, the unbalance of the optimum dynamic focus voltage generated between the center beam EB2 and the side beams EB1, EB3 can be suppressed.

Thus, like the electron gun 10 according to the first embodiment, since the distortion of the spot formed on the fluorescent screen by the side beams EB1, EB3 can be reduced, the R, G, B electron beams of EB1, EB2, EB3 The spot shape is substantially uniform in the middle region as well as the left and right end regions of the fluorescent screen 93. This makes it possible to implement the desired high resolution on the entire screen 93.

In addition, unlike the conventional electron gun disclosed in Japanese Unexamined Patent Publication No. 10-21847, no complicated configuration, additional pins, or additional circuits are required.

Third embodiment

18 and 19 show an inline electron gun 10A according to a third embodiment of the present invention.

The electron gun 10A shown in FIG. 18 has a configuration obtained by removing the intermediate electrode member 4b of the first focus electrode 4 from the electron gun 10 according to the first embodiment of FIG. That is, as shown in FIG. 18, the electron gun 10A is composed of the first focus electrode 4A having two electrode members 4a and 4c. Therefore, the description of the same configuration is omitted in this specification by adding the same reference numeral as the reference numeral of the electron gun 10 of the first embodiment to the same component of FIG.

In the electron gun 10A according to the third embodiment, as shown in FIG. 19, the fixed focus voltage E _C3S is applied to the electrode member 4c, while the dynamic focus voltage E _C3D is applied to the electrode member 4a and the first. Commonly applied to the two focus electrodes 5. The anode voltage Eb is applied to the final accelerating electrode 6.

The magnitudes of the fixed and dynamic focus voltages E _C3S and E _C3D are determined to satisfy the above equation (1). Specifically, the fixed and dynamic focus voltages E _C3S and E _C3D having the waveform shown in FIG. 12 are applied to the electron gun 10A.

In the electron gun 10A according to the third embodiment, as shown in FIG. 19, three rotationally symmetrical focus sub-lenses SL1, SL2, SL3 are disposed between the electrode members 4a, 4c of the first focus electrode 4A. Is formed. The focus sub lens SL1 is formed at a position corresponding to the openings 4a3 and 4c6 of the members 4a and 4c. The focus sub lens SL2 is formed at a position corresponding to the openings 4a2 and 4c5 of the members 4a and 4c. The focus sub lens SL3 is formed at a position corresponding to the openings 4a1 and 4c4 of the members 4a and 4c.

It is apparent that in the electron gun 10A according to the third embodiment of FIG. 18, it can give substantially the same advantages as that of the electron gun 10 according to the first embodiment of FIG. 8.

transform

In the inline electron gun according to the first, second and third embodiments of the present invention described above, the first focus electrode has two or three electrode members. However, the present invention is not limited to these. It goes without saying that the first focus electrode can have four or more electrode members.

Further, in the electron guns according to the first to third embodiments, each electrode member of the first focus electrode has a circular opening or through hole. However, the openings or through holes may have any other shape, such as polygonal or elliptical. The openings or through holes are sufficient to be able to form the focusing force of the R and B electron beams (ie, the side electron beams) that are different from the focusing force of the G electron beams (ie, the central electron beams).

In addition, portions other than the first focus electrode and the three cathodes may have a configuration different from that described in the above-described embodiment within the spirit of the present invention.

While the preferred form of the invention has been described, those skilled in the art will appreciate that modifications can be made without departing from the spirit of the invention. Accordingly, the scope of the invention will only be determined by the appended claims.

The present invention has the advantage of providing an inline electron gun which substantially uniformizes the spot shape of R, G, and B electron beams in the middle region of the fluorescent screen as well as the left and right end regions, and a color CRT equipped with the gun. .

Claims (7)

In the inline electron gun, (a) a tripolar vacuum tube for generating first, second and third electron beams and a main lens system for focusing the first, second and third electron beams respectively; (b) The three-pole vacuum tube may include the first, second and third cathodes arranged at a specific distance on the same line in a first direction, and the first, second and third at a specific distance in a second direction perpendicular to the first direction. 3 a control electrode disposed adjacent to the cathode, and an initial acceleration electrode disposed adjacent to the control electrode at a specific distance in the second direction; The first and third cathodes are arranged on opposite sides of the second cathode; (c) the main lens system comprises a first focus electrode, a second focus electrode, and a final acceleration electrode arranged in the second direction; The first focus electrode is disposed adjacent a specific distance to the initial acceleration electrode of the tripolar vacuum tube; The second focus electrode is disposed adjacent a specific distance with respect to the first focus electrode; The final accelerating electrode is disposed adjacent a specific distance with respect to the second focus electrode; (d) the first focus electrode has electrode members arranged at a particular distance or interval in the second direction; A first member of the electrode members is disposed adjacent to the initial acceleration electrode; The last member of the electrode members is disposed adjacent to the second focus electrode; The final member and the second focus electrode of the electrode members may include a first, second and third 4 for the first, second and third electron beams between the final member and the second focus electrode of the electrode members. Function to form a bipolar lens; Each of the electrode members of the first focus electrode has first, second and third through holes to allow the first, second and third electron beams to pass therethrough; The first and third through holes are identical in size to each other while the second through hole is different in size from the first and third through holes; (e) A fixed focus voltage is applied to the final member of the electrode members of the first focus electrode while a dynamic focus voltage is applied to the second focus electrode, thereby providing the electrode members of the first focus electrode. The first, second and third quadrupole lenses are formed between the final member and the second focus electrode; The first, second and third quadrupole lenses have a lens action that varies with the difference between the fixed and dynamic focus voltages; The dynamic focus voltage is applied to at least one of the electrode members of the first focus electrode except for the final member, so that the first, second, and third electron beams for the first, second, and third electron beams in the first focus electrode are applied. Second and third focus lenses are formed; The first, second and third focus lenses have a focusing force that varies with the difference between the fixed and dynamic focus voltages; The focusing force of the first and third focus lenses is changed at a ratio different from that of the second focus lens according to a difference between the fixed and dynamic focus voltages. Inline electron gun, characterized in that. The semiconductor device of claim 1, wherein the first and third through holes of each of the electrode members of the first focus electrode are smaller in size than the second through hole; And said fixed focus voltage is set to be greater in magnitude than said dynamic focus voltage. The semiconductor device of claim 1, wherein the first and third through holes of each of the electrode members of the first focus electrode are larger in size than the second through hole; And said fixed focus voltage is set to be smaller in magnitude than said dynamic focus voltage. The method of claim 1, wherein the number of the electrode members of the first focus electrode is three, and a third one of the electrode members functions as a final member; A second member of the electrode members is disposed at a specific distance between the first member and the third member of the electrode members; The fixed focus voltage is applied to the first and third members of the electrode members, while the dynamic focus voltage is applied to the second member of the electrode members. The method of claim 1, wherein the number of the electrode members of the first focus electrode is two, and a second one of the electrode members functions as a final member; The fixed focus voltage is applied to a first member of the electrode members while the dynamic focus voltage is applied to a second member of the electrode members. The method of claim 1, wherein the first, second and third through holes of each of the first and second members of the electrode members have a circular inlet and a circular outlet, respectively; Wherein said first, second and third through holes of said final member of said electrode members each have an inlet and a square outlet. The color CRT comprising the inline electron gun according to claim 1.