JP2007335299A - Color cathode-ray tube - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To alleviate unevenness of focusing performance while obtaining a superb focusing performance for a whole screen area. <P>SOLUTION: On a face of an emission side of three electron beams of a control electrode G1, three non-circular concave parts are formed having a major axis in an array direction of the three electron beams, and a minor axis in a direction crossing the array direction of the three electron beams. Three electron beam passing holes are formed on each bottom face of the three concave parts and are of non-circular shapes having a major axis in an array direction of the three electron beams and a minor axis in a direction crossing the array direction of the three electron beams. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a color cathode ray tube. In particular, the present invention relates to a color cathode ray tube adapted to obtain good image quality.

  In general, a color cathode ray tube includes an envelope in which a panel 1 and a funnel 2 are integrally joined as shown in FIG. A phosphor screen 4 composed of phosphor layers of three colors emitting red, green and blue is formed on the inner surface of the panel 1, and a shadow in which a large number of electron beam passage holes are formed facing the phosphor screen 4. A mask 3 is attached to the inner wall surface of the panel 1. An electron gun 6 that emits three electron beams 7B, 7G, and 7R is disposed in the neck portion 5 of the funnel 2. A deflection yoke 8 is mounted on the outer peripheral surface of the funnel 2 of the color cathode ray tube to constitute a color cathode ray tube device. The three electron beams 7B, 7G, and 7R emitted from the electron gun 6 are deflected by the magnetic field generated by the deflection yoke 8, pass through the electron beam passage holes of the shadow mask 3, and pass through the phosphor screen 4 in the horizontal and vertical directions. Scanning in the direction, a color image is displayed on the phosphor screen 4.

  Among such color cathode ray tubes, in particular, the electron gun 6 is an in-line type electron gun that emits three electron beams consisting of a center beam arranged in a row on the same horizontal plane and a pair of side beams on both sides, An in-line type color cathode ray tube that self-converges three electron beams on the phosphor screen 4 is generally used by using a horizontal deflection magnetic field generated by the deflection yoke 8 as a non-uniform magnetic field having a pincushion type and a vertical deflection magnetic field as a barrel type.

  There are various types of electron guns that emit three electron beams arranged in a row, but one type is called a BPF (Bi-Potential Focus) type static focus method.

  An example of this electron gun is shown in FIGS. 11 (A) and 11 (B). 11A is a horizontal cross-sectional view, and FIG. 11B is a vertical cross-sectional view. The central axis of the electron gun (that is, the tube axis of the color cathode ray tube) is taken as the Z axis. The direction orthogonal to the Z axis in the horizontal plane is defined as the horizontal direction, and the direction orthogonal to the Z axis in the vertical plane is defined as the vertical direction. An arrow 90 indicates the traveling direction of the electron beam.

  This electron gun has three cathodes K arranged in a row in the horizontal direction, and a control electrode G1, an acceleration electrode G2, a focus electrode G3, and an integral structure electrode S1, which are sequentially arranged on the phosphor screen (not shown) side. It consists of an anode electrode G4 and a shield cup SC attached to the phosphor screen side end of the anode electrode G4.

  In the control electrode G1 and the acceleration electrode G2, three electron beam passage holes corresponding to the three cathodes K arranged in a row are formed.

  The focus electrode G3 has three electron beam passage holes respectively corresponding to the three electron beams on the incident side end surface of the three electron beams, that is, the surface facing the acceleration electrode G2, and the three electron beam emission side end surface, that is, the anode electrode G4. And a cylindrical body 10 in which an elliptical electron beam passage hole 9 common to the three electron beams having a long axis in the arrangement direction (that is, the horizontal direction) of the three electron beams is formed on a surface opposite to the surface. An electric field correction plate 11 having three electron beam passage holes respectively corresponding to the three electron beams is disposed inside the cylindrical body 10.

  In the anode electrode G4, an elliptical electron beam passage hole 12 common to the three electron beams having a major axis in the arrangement direction of the three electron beams is formed on the incident side end face of the three electron beams, that is, the surface facing the focus electrode G3. A cylindrical body 13 is provided. An electric field correction plate 14 having three electron beam passage holes respectively corresponding to the three electron beams is disposed inside the cylinder 13.

  In this electron gun, a voltage on which a video signal of about 20 V to about 170 V is superimposed is applied to the cathode K, the control electrode G1 is grounded, and an acceleration voltage of 400 to 800 V is applied to the acceleration electrode G2. A focus voltage of 6 to 9 kV is applied to the focus electrode G3. An anode voltage of about 30 kV is applied to the anode electrode G4.

  As a result, the cathode K, the control electrode G1, and the acceleration electrode G2 form a tripolar portion that generates a three electron beam and forms an object point with respect to a main lens, which will be described later. A prefocus lens for prefocusing the three electron beams emitted from the unit is formed. Further, the focus electrode G3 and the anode electrode G4 form a BPF type main lens that finally accelerates and focuses the three electron beams on the phosphor screen.

  In order to improve the image quality of the color cathode ray tube, it is necessary to improve the focusing performance on the phosphor screen, that is, to reduce the electron beam spot on the entire phosphor screen.

  However, in a color cathode ray tube equipped with an in-line electron gun in particular, as shown in FIG. 12, the core 51 of the electron beam spot 50 is distorted into a horizontally long ellipse with the horizontal axis as the major axis, as shown in FIG. However, halos 52 are generated on both sides in the vertical direction, the electron beam spot is enlarged, and the focusing performance is deteriorated.

  The halo 52 generated above and below the core 51 is a non-uniform magnetic field in which the deflection magnetic field generated by the deflection yoke 8 to converge the three electron beams over the entire screen is a non-uniform magnetic field with a horizontal deflection magnetic field as a pincushion type and a vertical deflection magnetic field as a barrel type. The main reason is. That is, when the electron beam is deflected around the screen, the electron beam is strongly focused in the vertical direction by the deflection magnetic field, and the electron beam is overfocused in the vertical direction.

  This phenomenon is called deflection aberration, and becomes more prominent as the diameter of the electron beam passing through the deflection magnetic field increases. Therefore, if the divergence angle in the vertical direction of the electron beam emitted from the triode is reduced, the vertical diameter of the electron beam passing through the deflection magnetic field can be reduced, and the generation of the halo 52 due to the deflection aberration can be reduced. It becomes possible to reduce.

  As a first conventional technique for reducing the influence of deflection aberration, as shown in FIG. 13, three substantially rectangular recesses 15R having a major axis in the horizontal direction on the surface of the accelerating electrode G2 on the emission side of the three electron beams, There is a method in which 15G and 15B are formed, and electron beam passage holes 16R, 16G and 16B are formed on the bottom surfaces thereof. According to this method, it is possible to add astigmatism to the prefocus lens formed by the acceleration electrode G2 and the focus electrode G3, which has a relatively stronger focusing action in the vertical direction than the focusing action in the horizontal direction. Thereby, the electron beam passing through the prefocus lens is strongly focused in the vertical direction, the divergence angle of the electron beam in the vertical direction is reduced, and the deflection aberration is reduced.

  As another method of the first prior art, as shown in FIG. 14, three concave portions 17R, 17G, and 17B having a substantially rectangular shape whose major axis is perpendicular to the end surface on the three-electron beam incident side of the focus electrode G3. And electron beam passage holes 18R, 18G, and 18B are formed on the bottom surface of each of them. Also by this method, astigmatism with stronger focusing effect in the vertical direction than in the horizontal direction is added to the prefocus lens formed by the acceleration electrode G2 and the focus electrode G3, and the divergence angle of the electron beam in the vertical direction is increased. It is possible to reduce the influence of deflection aberration.

  However, if the divergence angle in the vertical direction of the electron beam is reduced by the first prior art method, the horizontal divergence angle of the electron beam is increased because the focusing effect of the prefocus lens in the horizontal direction is weak. The horizontal diameter of the electron beam incident on the main lens is enlarged. Therefore, when there is no allowance for the main lens aperture, there is a problem that the electron beam spot is strongly subjected to the spherical aberration of the main lens in the horizontal direction and the horizontal diameter of the electron beam spot is enlarged. Further, since the reduction of the divergence angle in the vertical direction of the electron beam is accompanied by an increase in the vertical diameter of the object point, there is a problem that the vertical diameter of the electron beam spot is increased. That is, in the first prior art described above, when the upper and lower halos 52 of the electron beam spot generated at the periphery of the screen are to be reduced, the horizontal diameter and the vertical diameter of the electron beam spot are enlarged over the entire screen. Therefore, there is no choice but to compromise, and there is a limit to the reduction of the divergence angle in the vertical direction of the electron beam.

  As a second conventional technique for solving such a problem, in addition to the first conventional technique described above, as shown in FIG. 15, the vertical direction of the electron beam passage holes 19R, 19G, 19B formed in the control electrode G1. There is a method of reducing the direction diameter to form a horizontally long hole. By reducing the vertical diameter of the electron beam passage hole of the control electrode G1, the vertical diameter of the object point is also reduced simultaneously with the reduction of the divergence angle of the electron beam in the vertical direction. It is possible to solve the problem that the vertical diameter of an object point increases.

  However, the second prior art method has a problem that since the opening area of the electron beam passage hole of the control electrode G1 is reduced, the load on the cathode K is increased and the life of the cathode K is shortened. Although the life of the cathode K can be improved by using an impregnated cathode as the cathode K, there is a problem that the cost increases.

  Further, if the vertical diameter of the electron beam passage hole of the control electrode G1 is reduced and the horizontal diameter is enlarged to maintain the opening area of the electron beam passage hole, the life of the cathode K can be shortened by increasing the load of the cathode K. The problem can be avoided. However, there is a problem that the horizontal divergence angle of the electron beam and the horizontal diameter of the object point are enlarged, and the horizontal diameter of the electron beam spot is enlarged.

  In order to solve the problem of expanding the horizontal diameter of the electron beam spot due to the expansion of the divergence angle of the electron beam in the horizontal direction and the expansion of the horizontal diameter of the object point, the main lens aperture is expanded to reduce spherical aberration and lens magnification. It is effective to reduce it. However, in order to enlarge the main lens aperture while maintaining the diameter of the neck portion 5, an intermediate electrode is inserted between the anode electrode G4 and the focus electrode G3, and the resistor built in the electron gun is changed to the intermediate electrode. There is a problem that a method for supplying voltage is required, and the cost increases due to an increase in the number of components. Further, if the diameter of the neck portion 5 is increased, the actual dimensions of the electrode can be increased and the main lens aperture can be increased, but the power required for deflecting the electron beam increases, and the monitor set In addition, there is a problem that the cost of the TV set is increased and the power consumption is increased. This problem is particularly serious when the deflection angle is widened in order to reduce the dimension of the cathode ray tube in the tube axis direction.

  As a third conventional technique for solving the above problem, there is a method disclosed in Patent Document 1. In this method, in the control electrode G1 shown in FIG. 15, the ratio G1v / G1h of the opening diameter G1v in the vertical direction to the opening diameter G1h in the horizontal direction of the electron beam passage holes 19R, 19G, 19B is 0.35 or more and 0. The horizontal aperture G2h of the electron beam passage holes 20R, 20G, and 20B formed in the accelerating electrode G2 as shown in FIG. The vertical opening diameter G2v of the electron beam passage holes 20R, 20G, and 20B is made smaller than the horizontal opening diameter G1h of the passage holes 19R, 19G, and 19B, and the vertical opening diameter of the electron beam passage holes 19R, 19G, and 19B is opened. It is made larger than the aperture G1v. According to this method, an electric field having a strong divergence effect in the horizontal direction is formed in the vicinity of the electron beam passage holes 20R, 20G, and 20B of the acceleration electrode G2, so that no crossover is formed in the horizontal direction, and the prefocus lens The horizontal divergence angle of the electron beam incident on is reduced. Therefore, even if strong astigmatism is added to the prefocus lens to reduce the vertical divergence angle of the electron beam, it is possible to suppress the expansion of the horizontal divergence angle of the electron beam. It is said that the focus performance can be improved.

However, in this method, the horizontal opening diameter G1h of the electron beam passage holes 19R, 19G, 19B of the control electrode G1 is larger than the horizontal opening diameter G2h of the electron beam passage holes 20R, 20G, 20B of the acceleration electrode G2. Due to the large size, the position of the control electrode G1 cannot be restricted when the position restricting rod is inserted into the electron beam passage hole of each electrode from the anode electrode G4 side to align the axes of the electrodes in the manufacturing process of the electron gun. Therefore, it is difficult to align the control electrode G1 with the axis of the other electrode with high accuracy, and there is a problem in that quality variations such as focusing performance tend to occur. Further, if the opening areas of the electron beam passage holes 19R, 19G, and 19B of the control electrode G1 are maintained to be equal to the conventional one, the problem that the horizontal diameter of the object point increases and the horizontal diameter of the electron beam spot increases cannot be solved. Further, there is a problem that it is difficult to accurately form the slit-shaped electron beam passage holes 19R, 19G, and 19B in the control electrode G1 having a small ratio G1v / G1h of the vertical opening diameter G1v to the horizontal opening diameter G1h. .
European Patent Application No. 1 495 538

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a color cathode ray tube with little variation in focus performance while obtaining good focus performance over the entire screen.

  The color cathode ray tube of the present invention is formed with three cathodes for generating three electron beams comprising a center electron beam arranged in a row and a pair of side electron beams, and three electron beam passage holes arranged in a row. A control electrode and an accelerating electrode arranged in order along the traveling direction of the three electron beam, and at least the accelerating electrode and the focus for prefocusing the three electron beam emitted from the three pole part. A pre-focus lens formed of a plurality of electrodes including electrodes, and a plurality of electrodes including at least the focus electrode and the anode electrode for finally accelerating and focusing the three electron beams on the phosphor screen. And an electron gun having a main lens.

  Three non-circular pieces having a major axis in the arrangement direction of the three electron beam and a minor axis in a direction perpendicular to the arrangement direction of the three electron beam on the surface of the control electrode on the emission side of the three electron beam Are formed.

  The three electron beam passage holes of the control electrode are respectively formed on the bottom surfaces of the three concave portions, have a long axis in the arrangement direction of the three electron beams, and the arrangement direction of the three electron beams; It is non-circular with a minor axis in the orthogonal direction.

  According to the present invention, it is possible to provide a color cathode ray tube capable of obtaining good focusing performance over the entire screen and having little variation in focusing performance.

  FIG. 3 is a perspective view showing a control electrode G1 of an in-line type electron gun that emits three electron beams arranged in a line in the horizontal direction, which is mounted on the color cathode ray tube of the present invention. The control electrode G1 has a major axis in the arrangement direction of the three electron beams (that is, the horizontal direction) on the surface on the emission side of the three electron beams, and in a direction orthogonal to the arrangement direction of the three electron beams (that is, the vertical direction) Three horizontally long non-circular recesses 21R, 21G, and 21B having a short axis are formed. The bottom surfaces of the three recesses 21R, 21G, and 21B have a major axis in the arrangement direction of three electron beams (that is, a horizontal direction) and a minor axis in a direction orthogonal to the arrangement direction of three electron beams (that is, a vertical direction). Horizontally long non-circular electron beam passage holes 22R, 22G, and 22B having the above are respectively formed. The three electron beam passage holes 22R, 22G, and 22B are arranged in a row in the horizontal direction.

  The horizontally long electron beam passage holes 22R, 22G, and 22B have the effect of reducing the divergence angle of the electron beam in the vertical direction and increasing the divergence angle of the electron beam in the horizontal direction.

  Further, the horizontally long recesses 21R, 21G, and 21B have a first effect of reducing the vertical divergence angle of the electron beam. This is because the recesses 21R, 21G, and 21B have a horizontally long shape, so that the penetration of the potential from the acceleration electrode G2 into the recesses 21R, 21G, and 21B is less in the vertical direction than in the horizontal direction, and the cathode K This is because the electron emission region is narrowed in the vertical direction.

  Further, the horizontally elongated recesses 21R, 21G, and 21B have a second effect of reducing the divergence angle of the electron beam in the horizontal direction. This is because a lens electric field having astigmatism having a weak focusing effect in the horizontal direction than in the vertical direction is formed at a position closer to the cathode K than the position where the electron beam forms a crossover.

  Accordingly, the effect that the horizontally elongated electron beam passage holes 22R, 22G, and 22B increase the divergence angle in the horizontal direction of the electron beam is that the horizontally elongated electron beam passage holes 22R, 22G, and 22B form an astigmatism lens electric field. Is offset by the effect of In addition, the horizontally long electron beam passage holes 22R, 22G, and 22B reduce the divergence angle in the vertical direction of the electron beam, and the horizontally long recesses 21R, 21G, and 21B reduce the divergence angle in the vertical direction of the electron beam. Is added to the effect. As a result, the divergence angle in the vertical direction of the electron beam can be reduced more than before without excessively increasing the divergence angle in the horizontal direction of the electron beam.

  FIG. 4 is a diagram showing the relationship between the opening shape of the electron beam passage holes 22R, 22G, and 22B formed in the control electrode G1 and the performance of the tripolar portion. In FIG. 4, the vertical axis represents the ratio G1v / G1h of the vertical opening diameter G1v to the horizontal opening diameter G1h of the electron beam passage holes 22R, 22G, and 22B. The horizontal axis is a value obtained by converting the product α · dx of the beam divergence angle α and the virtual object point diameter dx with the value when the ratio G1v / G1h = 1 being 1 (hereinafter referred to as “ratio α · dx”). It is. Here, the beam divergence angle α and the virtual object point diameter dx are both average values of the horizontal value and the vertical value. The smaller the ratio α · dx, the higher the performance of the tripolar part.

  FIG. 4 shows that the ratio α · dx is 1 or less in the range where the ratio G1v / G1h is larger than 0.53 and smaller than 1.0, and the effect of the present invention is exhibited well. It has been found from experiments by the present inventors that even better results can be obtained if the ratio α · dx is 0.95 or less. Therefore, it is desirable that the ratio G1v / G1h is larger than 0.6 and smaller than 0.85.

  As described above, since the electron beam passage holes 22R, 22G, and 22B do not need to be extremely horizontally long, the horizontal diameters of the object points can be maintained even if the opening areas of the electron beam passage holes 22R, 22G, and 22B are maintained at the same level as in the past. The enlargement of the horizontal diameter of the electron beam spot due to the enlargement of the electron beam is suppressed to a level that is hardly or hardly observed, and there is no problem in the formation accuracy of the electron beam passage hole.

  FIG. 5 is a perspective view showing an acceleration electrode G2 of an in-line electron gun mounted on the color cathode ray tube of the present invention. The acceleration electrode G2 is formed with three electron beam passage holes 23R, 23G, and 23B arranged in a line in the horizontal direction. A direction orthogonal to the arrangement direction of the three electron beams and the opening diameter G2Bh in the arrangement direction (that is, the horizontal direction) of the three electron beams of the electron beam passage holes 23R, 23G, and 23B on the surface on the incident side of the three electron beams of the acceleration electrode G2. The opening diameter G2Bv in the vertical direction (that is, the vertical direction) and the opening diameter G1h in the major axis direction and the opening diameter G1v in the minor axis direction of the electron beam passage holes 22R, 22G, 22B formed in the control electrode G1 are G2Bh ≧ G1h and It is preferable that G2Bv> G1v is satisfied. As long as this is satisfied, the opening shapes of the electron beam passage holes 23R, 23G, and 23B on the surface on the incident side of the three electron beams of the acceleration electrode G2 may be circular or non-circular.

  If the aperture shape of the electron beam passage holes 23R, 23G, and 23B of the acceleration electrode G2 on the surface on the incident side of the three electron beams satisfies the above, a position closer to the cathode K than a position where the electron beam forms a crossover, That is, a lens electric field having astigmatism with a weaker focusing effect in the vertical direction than in the horizontal direction is formed in the vicinity of the electron beam passage holes 23R, 23G, and 23B of the acceleration electrode G2, so that the divergence angle of the electron beam in the vertical direction is formed. Can be further reduced. Further, since the opening diameters of the electron beam passage holes 23R, 23G, and 23B of the acceleration electrode G2 are equal to or larger than the opening diameters of the electron beam passage holes 22R, 22G, and 22B of the control electrode G1, the electron beam passage of each electrode is performed. It is possible to implement a method of assembling an electron gun by inserting a position restricting rod into the hole and aligning the axes of the respective electrodes, and it is possible to suppress variation in focus performance due to poor assembly accuracy.

  6A and 6B are diagrams showing another acceleration electrode G2, FIG. 6A is a perspective view seen from the electron beam emitting side, and FIG. 6B is seen from the electron beam incident side. FIG. This accelerating electrode G2 has electron beam passage holes 23R, 23G, and 23B on both sides in that the opening size of the electron beam passage hole is different between the surface on which the three electron beams are emitted and the surface on the incident side. Are different from the acceleration electrode G2 of FIG. A direction orthogonal to the arrangement direction of the three electron beams and the opening diameter G2Th in the arrangement direction (that is, the horizontal direction) of the three electron beams of the electron beam passage holes 24R, 24G, and 24B on the surface on the emission side of the three electron beams of the acceleration electrode G2. That is, the opening diameter G2Tv in the vertical direction) and the opening diameters G2Bh and 3 in the arrangement direction (that is, the horizontal direction) of the three electron beams of the electron beam passage holes 25R, 25G, and 25B on the surface on the incident side of the three electron beams of the acceleration electrode G2. It is preferable that the aperture diameter G2Bv in the direction orthogonal to the electron beam arrangement direction (ie, the vertical direction) satisfy G2Th> G2Bh and G2Tv> G2Bv. As long as this is satisfied, the opening shapes of the electron beam passage holes 24R, 24G, and 24B on the surface of the accelerating electrode G2 on the emission side of the three electron beams may be circular or non-circular.

  When the aperture shapes on both surfaces of the electron beam passage hole of the acceleration electrode G2 satisfy the above, the aperture of the prefocus lens formed by the acceleration electrode and the focus electrode is enlarged, and a prefocus lens with less spherical aberration is formed. As a result, the increase of the virtual object point diameter accompanying the reduction of the divergence angle of the electron beam is suppressed, so that the divergence angle of the electron beam can be further reduced.

  Further, the prefocus lens formed by the accelerating electrode and the focus electrode is focused in a direction perpendicular to the arrangement direction of the three electron beams (that is, the vertical direction) rather than a focusing action in the arrangement direction of the three electron beams (that is, the horizontal direction). It is preferable to have astigmatism having a relatively strong action. As a result, the divergence angle in the vertical direction of the electron beam can be further reduced while the divergence angle in the horizontal direction of the electron beam is appropriate.

  As described above, according to the present invention, the vertical divergence angle of the electron beam is reduced more than before, thereby reducing the upper and lower halos generated in the electron beam spot at the periphery of the screen due to the deflection aberration. It is possible to prevent an excessive expansion of the divergence angle of the beam in the horizontal direction and an accompanying increase in the horizontal diameter of the electron beam spot. Further, it is possible to implement an electron gun assembling method in which a position restricting rod is inserted into the electron beam passage hole of each electrode so that the axes of the electrodes coincide with each other. Therefore, it is possible to provide a color cathode ray tube that can obtain good focusing performance over the entire screen and has little variation in focusing performance.

  Hereinafter, the present invention will be described in more detail with reference to specific embodiments.

  The basic configuration of the color cathode ray tube of the present invention is not particularly limited except for the electron gun, and may be the same as that shown in FIG. Therefore, the overlapping description about the same part as the conventional one is omitted.

(Embodiment 1)
1A and 1B are diagrams showing a schematic configuration of an electron gun mounted on a color cathode ray tube according to Embodiment 1 of the present invention, in which FIG. 1A is a horizontal sectional view thereof, and FIG. 1B is a vertical sectional view thereof. FIG. The central axis of the electron gun (that is, the tube axis of the color cathode ray tube) is taken as the Z axis. The direction orthogonal to the Z axis in the horizontal plane is defined as the horizontal direction, and the direction orthogonal to the Z axis in the vertical plane is defined as the vertical direction. An arrow 90 indicates the traveling direction of the electron beam.

  This electron gun is an in-line type electron gun that emits three electron beams consisting of a center beam arranged in a row on the same horizontal plane and a pair of side beams on both sides thereof, and three cathodes K arranged in a row in the horizontal direction. The control electrode G1, the accelerating electrode G2, the focus electrode G3, the anode electrode G4, and the anode electrode G4, which are sequentially arranged on the phosphor screen (not shown) side, are attached to the phosphor screen side end of the anode electrode G4. The shield cup SC.

  As shown in FIG. 3, the surface on the emission side of the three electron beams of the control electrode G1 has three substantially rectangular shapes with a horizontal dimension G1Sh of about 2 mm and a vertical dimension G1Sv of 0.4 mm to 0.7 mm. The recesses 21R, 21G, and 21B are formed on a straight line in the horizontal direction corresponding to the three cathodes K arranged in a row. On the bottom surfaces of the three recesses 21R, 21G, and 21B, three substantially rectangular electrons having a horizontal opening diameter G1h of 0.6 mm to 0.9 mm and a vertical opening diameter G1v of 0.4 to 0.6 mm are provided. Beam passage holes 22R, 22G, and 22B are formed, respectively. The plate thickness (Z-axis direction dimension) of the control electrode G1 is selected in the range of 0.1 mm to 0.3 mm. The vertical dimension G1Sv of the recesses 21R, 21G, and 21B is desirably about 0 to 0.15 mm larger than the vertical opening diameter G1v of the electron beam passage holes 22R, 22G, and 22B. The depth of the recesses 21R, 21G, and 21B is desirably in the range of 20 to 80% of the plate thickness of the control electrode G1.

  As shown in FIG. 5, in the acceleration electrode G2, three electron beam passage holes 23R, 23G, and 23B are formed on a straight line in the horizontal direction corresponding to the three cathodes K arranged in a row. On the surface on the incident side of the three electron beams of the acceleration electrode G2, the horizontal aperture diameter G2Bh of the electron beam passage holes 23R, 23G, and 23B is 0.6 to 0.9 mm, and the vertical aperture diameter G2Bv is 0.6 to 1. It is 5 mm, and its opening shape is circular or non-circular. Furthermore, the dimensions are selected so that G2Bh ≧ G1h and G2Bv> G1v are satisfied with respect to the horizontal direction opening diameter G1h and the vertical direction opening diameter G1v of the electron beam passage holes 22R, 22G, 22B of the control electrode G1. The plate thickness (Z-axis direction dimension) of the acceleration electrode G2 is selected in the range of 0.2 mm to 0.8 mm.

  As shown in FIG. 7, the focus electrode G3 has three vertically long apertures having a horizontal aperture diameter of 0.9 to 2.0 mm and a vertical aperture diameter of 1.3 to 4.0 mm on the incident surface of the three electron beams. Electron beam passage holes 26R, 26G, and 26B are formed, and a generally elliptical electron beam passage hole that is common to three electron beams having a major axis in the horizontal direction and a minor axis in the vertical direction on the emission side end face of the three electron beams. 27 is provided with a cylindrical body 28 on which 27 is formed. An electric field correction plate 29 in which three electron beam passage holes corresponding to the three electron beams are formed is disposed inside the cylinder 28.

  The anode electrode G4 has a cylindrical body 31 in which an approximately elliptical electron beam passage hole 30 common to the three electron beams having a major axis in the horizontal direction and a minor axis in the vertical direction is formed on the end surface of the incident side of the three electron beams. Is provided. An electric field correction plate 32 having three electron beam passage holes respectively corresponding to the three electron beams is disposed inside the cylindrical body 31.

  In this electron gun, a voltage on which a video signal of about 20 V to about 170 V is superimposed is applied to the cathode K, the control electrode G1 is grounded, and an acceleration voltage of 400 to 800 V is applied to the acceleration electrode G2. A focus voltage of 6 to 9 kV is applied to the focus electrode G3. An anode voltage of about 30 kV is applied to the anode electrode G4.

  By providing the electron gun as described above, it is possible to effectively reduce the vertical divergence angle of the electron beam while optimizing the horizontal divergence angle of the electron beam, and to improve the focusing performance at the periphery of the screen. Can be improved.

(Embodiment 2)
2A and 2B are diagrams showing a schematic configuration of an electron gun mounted on a color cathode ray tube according to Embodiment 2 of the present invention, where FIG. 2A is a horizontal sectional view thereof, and FIG. 2B is a vertical sectional view thereof. FIG. The central axis of the electron gun (that is, the tube axis of the color cathode ray tube) is taken as the Z axis. The direction orthogonal to the Z axis in the horizontal plane is defined as the horizontal direction, and the direction orthogonal to the Z axis in the vertical plane is defined as the vertical direction. An arrow 90 indicates the traveling direction of the electron beam.

  The second embodiment is different from the first embodiment only in the acceleration electrode G2. The description of the same parts as those in Embodiment 1 is omitted.

  6 (A) and 6 (B) are diagrams showing the acceleration electrode G2 of the second embodiment, FIG. 6 (A) is a perspective view seen from the electron beam emitting side, and FIG. 6 (B) is an electron. It is the perspective view seen from the beam incident side.

  On the surface of the accelerating electrode G2 on the incident side of the three electron beams, the electron beam passage holes 25R, 25G, 25B have a horizontal opening diameter G2Bh of 0.6 to 0.9 mm and a vertical opening diameter G2Bv of 0.6 to 1. It is 5 mm, and its opening shape is circular or non-circular. Furthermore, the dimensions are selected so that G2Bh ≧ G1h and G2Bv> G1v are satisfied with respect to the horizontal direction opening diameter G1h and the vertical direction opening diameter G1v of the electron beam passage holes 22R, 22G, 22B of the control electrode G1.

  On the surface of the accelerating electrode G2 on the emission side of the three electron beams, the horizontal aperture diameter G2Th of the electron beam passage holes 24R, 24G, 24B is 0.9 to 2.0 mm, and the vertical aperture diameter G2Tv is 1.0 to 3. 0 mm, and the opening shape is circular or non-circular. Further, the respective dimensions are selected so as to satisfy G2Th> G2Bh and G2Tv> G2Bv.

  The plate thickness (Z-axis direction dimension) of the acceleration electrode G2 is selected in the range of 0.5 mm to 2.5 mm.

  The second embodiment is slightly disadvantageous compared to the first embodiment in that the cost of the acceleration electrode G2 is increased, but it is possible to obtain the effects of the first embodiment or more.

  The present invention is not limited to the first and second embodiments, and various modifications can be made.

  In the acceleration electrode G2 shown in FIG. 2 and FIG. 6 shown in the second embodiment, three electron beam passage holes 24R, 24G formed from the surface on the side from which the three electron beams are emitted with respect to a single plate material. 24B and the three electron beam passage holes 25R, 25G, and 25B formed from the surface on which the three electron beams are incident were continuous with each other in the plate material. However, the acceleration electrode G2 is not limited to this. For example, as in the acceleration electrode G2 shown in FIGS. 8A and 8B, a plate material on the side from which three electron beams are emitted, in which three electron beam passage holes 24R, 24G, and 24B are formed, and 3 The plate materials on the side on which the three electron beams on which the electron beam passage holes 25R, 25G, and 25B are formed may be joined to each other. Regardless of the internal structure of the acceleration electrode G2, the opening diameters G2Th and G2Tv on the emission side surface of the three electron beams and the opening diameters G2Bh and G2Bv on the incident side surface of the three electron beam passage holes formed in the acceleration electrode G2 are as follows. If the above relationship is satisfied, the above effect of the present invention can be obtained.

  In the first and second embodiments, the three electron beam passage holes provided on the three electron beam incident side end face of the focus electrode G3 have a vertically long shape as shown in FIG. 7, but the shape is not limited thereto. . In the present invention, the prefocus lens formed by the accelerating electrode G2 and the focus electrode G3 only needs to have astigmatism with a stronger focusing effect in the vertical direction than a focusing effect in the horizontal direction. Therefore, for example, as shown in FIG. 9, three vertically long non-circular recesses 33B, 33G, and 33R are formed on the end surface of the focus electrode G3 on the incident side of the three electron beams, and the electron beam passage holes 34B, 34G, and Even if 34R is formed, the above-described effects of the present invention can be obtained. In addition, the three electron beam passage holes formed on the end surface of the focus electron G3 on the incident side of the three electron beam are circular, and the opening shape of the electron beam passage hole on the surface of the acceleration electrode G2 on the emission side of the three electron beam is horizontally long. It may be non-circular.

  In the first and second embodiments, the example in which the present invention is applied to the BPF type static focus type electron gun has been described. However, the type of the electron gun is not limited to this. For example, the present invention is applied to a dynamic focus type electron gun in which a focus electrode is composed of a plurality of electrodes and a dynamic focus voltage that changes in synchronization with the deflection amount of an electron beam is applied to at least one of the electrodes. You can also. Further, the present invention can be applied to a multistage focusing type electron gun including a prefocusing lens between a prefocus lens and a main lens.

  In the first and second embodiments, the main lens is a general electric field superposition type lens formed by an electron beam passage hole common to the three electron beams, but the three electron beams are finally put on the phosphor screen. If it can accelerate and focus, it will not be limited to this. For example, it may be a main lens formed by three electron beam passage holes through which three electron beams pass.

  The application field of the present invention is not particularly limited, and can be widely used for various applications as a color cathode ray tube capable of obtaining good and stable image quality.

1A and 1B are diagrams showing a schematic configuration of an electron gun mounted on a color cathode ray tube according to Embodiment 1 of the present invention, in which FIG. 1A is a horizontal sectional view thereof, and FIG. 1B is a vertical sectional view thereof. FIG. 2A and 2B are diagrams showing a schematic configuration of an electron gun mounted on a color cathode ray tube according to Embodiment 2 of the present invention, where FIG. 2A is a horizontal sectional view thereof, and FIG. 2B is a vertical sectional view thereof. FIG. FIG. 3 is a perspective view showing the control electrode of the electron gun mounted on the color cathode ray tube of the present invention. FIG. 4 is a diagram showing a change in performance of the triode portion with respect to the aspect ratio of the electron beam passage hole formed in the control electrode of the electron gun mounted on the color cathode ray tube of the present invention. FIG. 5 is a perspective view showing an acceleration electrode of an electron gun mounted on the color cathode ray tube of the present invention. 6A and 6B are diagrams showing another acceleration electrode of the electron gun mounted on the color cathode ray tube of the present invention. FIG. 6A is a perspective view seen from the electron beam emitting side, and FIG. FIG. FIG. 7 is a perspective view of an example of the electron beam incident side end face of the focus electrode of the electron gun mounted on the color cathode ray tube of the present invention. 8A and 8B are views showing still another acceleration electrode of the electron gun mounted on the color cathode ray tube of the present invention. FIG. 8A is a perspective view seen from the electron beam emitting side, and FIG. 8B is an electron beam incident side. It is the perspective view seen from. FIG. 9 is a perspective view of another example of the electron beam incident side end face of the focus electrode of the electron gun mounted on the color cathode ray tube of the present invention. FIG. 10 is a cross-sectional view showing a schematic configuration of an example of a color cathode ray tube. 11A and 11B are diagrams showing a schematic configuration of a conventional electron gun. FIG. 11A is a horizontal sectional view thereof, and FIG. 11B is a vertical sectional view thereof. FIG. 12 is a diagram showing the shape of an electron beam spot on the screen of a conventional color cathode ray tube. FIG. 13 is a perspective view showing an acceleration electrode to which the first prior art is applied. FIG. 14 is a perspective view showing an electron beam incident side surface of a focus electrode to which the first prior art is applied. FIG. 15 is a perspective view showing a control electrode to which the second prior art is applied. FIG. 16 is a perspective view showing an acceleration electrode to which the third prior art is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Panel 2 Funnel 3 Shadow mask 4 Phosphor screen 5 Neck part 6 Electron gun 7B, 7G, 7R Electron beam 8 Deflection yoke K Cathode G1 Control electrode G2 Acceleration electrode G3 Focus electrode G4 Anode electrode SC Shield cup

Claims (6)

Three cathodes for generating three electron beams composed of a center electron beam arranged in a row and a pair of side electron beams, and a control electrode and an acceleration electrode each having three electron beam passage holes arranged in a row are formed. A tripolar portion sequentially disposed along the traveling direction of the three electron beams;
A prefocus lens formed by a plurality of electrodes including at least the acceleration electrode and the focus electrode, which prefocuses the three electron beams emitted from the tripolar portion;
A color cathode ray tube comprising an electron gun comprising: a main lens formed of a plurality of electrodes including at least the focus electrode and the anode electrode, which finally accelerates and focuses the three electron beams on a phosphor screen. And
Three non-circular pieces having a major axis in the arrangement direction of the three electron beam and a minor axis in a direction perpendicular to the arrangement direction of the three electron beam on the surface of the control electrode on the emission side of the three electron beam Are formed,
The three electron beam passage holes of the control electrode are respectively formed on the bottom surfaces of the three concave portions, have a long axis in the arrangement direction of the three electron beams, and the arrangement direction of the three electron beams; A color cathode ray tube characterized by being non-circular having a minor axis in an orthogonal direction.   2. The color according to claim 1, wherein an opening diameter G1h in a major axis direction and an opening diameter G1v in a minor axis direction of the electron beam passage hole formed in the control electrode satisfy 0.53 <G1v / G1h <1.0. Cathode ray tube.   2. The color according to claim 1, wherein an opening diameter G1h in a major axis direction and an opening diameter G1v in a minor axis direction of the electron beam passage hole formed in the control electrode satisfy 0.6 <G1v / G1h <0.85. Cathode ray tube.   The surface of the accelerating electrode on the incident side of the three electron beam is orthogonal to the opening diameter G2Bh of the electron beam passage hole formed in the accelerating electrode in the arrangement direction of the three electron beam and the arrangement direction of the three electron beam. The opening diameter G2Bv in the direction and the opening diameter G1h in the major axis direction and the opening diameter G1v in the minor axis direction of the electron beam passage hole formed in the control electrode satisfy G2Bh ≧ G1h and G2Bv> G1v. The color cathode ray tube in any one of -3.   The surface of the accelerating electrode on the emission side of the three electron beam is orthogonal to the opening diameter G2Th of the electron beam passage hole formed in the acceleration electrode in the arrangement direction of the three electron beam and the arrangement direction of the three electron beam. Direction aperture diameter G2Tv, the aperture diameter G2Bh in the arrangement direction of the three electron beams of the electron beam passage hole formed in the acceleration electrode on the surface of the acceleration electrode on the incident side of the three electron beams, and the three electrons The color cathode ray tube according to any one of claims 1 to 4, wherein an aperture diameter G2Bv in a direction orthogonal to the beam arrangement direction satisfies G2Th> G2Bh and G2Tv> G2Bv.   2. The prefocus lens has astigmatism in which a focusing action in a direction orthogonal to the arrangement direction of the three electron beams is relatively stronger than a focusing action in the arrangement direction of the three electron beams. The color cathode ray tube according to any one of 5.

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