JP2004079404A - Cathode-ray tube for projection, and projection display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that coma aberration affects the spot shape of an electron beam and distorts the spot shape when a distortion of an image on a projecting screen is corrected by using a sub deflection yoke. <P>SOLUTION: A cathode-ray tube for projection comprises an electron gun which forms a main lens 22 for beam focusing on a trajectory of an electron beam emitted from a cathode 21; a main deflection yoke 17 which forms a main deflection magnetic field deflecting an electron beam ejected from an electron gun 19; a sub deflection yoke 18 which is located at a place close to the back end of the main deflection yoke 17, and forms a correction magnetic field ϕH1 to correct the image distortion on the projection screen; and a yoke for coma aberration correction 23 which is located at a place closer to the cathode 21 than a formation portion of the main lens 22 and forms a coma aberration correction magnetic field ϕH2 directed in the direction opposite to the correction magnetic field ϕH1 formed by the sub deflection yoke 18. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a projection cathode ray tube having a sub-deflection yoke for correcting image distortion and a projection display device using the same.
[0002]
[Prior art]
Generally, in a projection display device using a projection cathode ray tube (for example, a projection television device), three projection cathode ray tubes for a red image, a green image, and a blue image are separated by a predetermined distance from a projection screen. By arranging them at remote positions and projecting the reproduced images displayed on the face plates of the three projection cathode ray tubes onto a projection screen, the reproduced images displayed on the face plates of the respective projection cathode ray tubes are reduced. It is designed to display the enlarged image on the projection screen.
[0003]
FIGS. 5A and 5B schematically show a configuration example of a projection display device, wherein FIG. 5A is a side view and FIG. 5B is a front view. Inside the projection display device 1, a projection cathode ray tube for red image (hereinafter abbreviated as cathode ray tube for red) 2 and a cathode ray tube for green image (hereinafter abbreviated as green cathode ray tube) 3 are provided. A projection cathode ray tube (hereinafter abbreviated as a blue cathode ray tube) 4 for a blue image is incorporated. In the vicinity of the face plate of the cathode ray tube 2 for red, a projection lens 5 for red image is arranged facing the center plate so as to be aligned therewith. Similarly, a projection lens 6 for a green image is disposed in the vicinity of the face plate of the cathode ray tube 3 for green with the central axis aligned with the projection plate 6 in the opposed state, and in the vicinity of the face plate of the cathode ray tube 4 for blue. The projection lens 7 for a blue image is arranged in a state where the projection lens 7 is opposed to the center axis of the projection lens 7.
[0004]
On the other hand, a projection screen 8 is vertically arranged on the front surface of the projection display device 1. On the back side of the projection display device 1, a reflection plate 9 is arranged obliquely so as to face the projection screen 8. The projection screen 8 is for projecting an image displayed on the face plate of each of the cathode ray tubes 2, 3, and 4. The projection screen 8 has light transmissivity for transmitting an optical image projected on the screen rear side to the screen front side. The reflection plate 9 is arranged between the projection screen 8 and the projection lens 6 for the green image with their central axes aligned.
[0005]
In the projection display device 1 described above, the images (red image, green image, and blue image) displayed on the face plates of the red cathode ray tube 2, the green cathode ray tube 3, and the blue cathode ray tube 4 correspond respectively. The light is condensed and magnified through the projection lenses 5, 6, and 7 which are to be projected. The enlarged image of each color is reflected by the reflector 9 and projected on the projection screen 8. Accordingly, a color image in which three color images of red, green and blue are superimposed is displayed on the projection screen 8.
[0006]
FIG. 6 is a cross-sectional view showing a configuration example of a projection cathode ray tube used for a projection display device. The illustrated projection cathode ray tube 10 is applied to the above-described red cathode ray tube 2, green cathode ray tube 3, and blue cathode ray tube 4, respectively. A glass bulb serving as a main body of the projection cathode ray tube 10 includes a panel portion 11, a funnel portion 12 joined to the panel portion 11, and a neck portion 13 integrally extending from the funnel portion 12. It is configured. The panel unit 11 integrally has a face plate 14 for displaying an image. A phosphor screen 15 is formed on the inner surface of the face plate 14 of the panel section 11. The funnel 12 is formed in a funnel shape. The funnel section 12 is provided with an anode button 16 for applying an anode voltage. A main deflection yoke 17 is mounted on a cone portion extending from the funnel portion 12 to the neck portion 13, and a sub deflection yoke 18 is arranged near a rear end of the main deflection yoke 17. The sub deflection yoke 18 is mounted on the neck 13. The neck portion 13 is formed in a cylindrical shape. An electron gun 19 is incorporated in the neck 13. A stem 20 is attached to an end of the neck 13.
[0007]
In the projection cathode ray tube 10, an electron beam (not shown) emitted from an electron gun 19 is deflected up, down, left and right by a main deflection magnetic field of a main deflection yoke 17. Thus, the electron beam spot is scanned in the horizontal direction and the vertical direction on the phosphor screen 15, and a monochrome image is displayed on the face plate 14 by the scanning of the beam spot. The color of the image displayed at this time corresponds to the color of the phosphor forming the phosphor screen 15.
[0008]
Here, in the projection type display device 1 described above, a cross-pattern figure with square cells is displayed on each face plate of the red cathode ray tube 2, the green cathode ray tube 3, and the blue cathode ray tube 4, and the projection screen 2 is displayed. 7A, cross pattern figures corresponding to the respective image colors are displayed on the projection screen 8 as shown in FIGS. That is, the cross pattern graphic corresponding to the red image is an image distorted into a horizontal trapezoidal shape as shown in FIG. 7A, and the cross pattern graphic corresponding to the green image is a vertical trapezoidal shape as shown in FIG. As shown in FIG. 7C, the cross pattern figure corresponding to the blue image is an image distorted into a horizontal trapezoid in which the distortion shape in the case of the red image is horizontally inverted.
[0009]
Therefore, conventionally, the distortion of the image on the projection screen 8 is corrected by using the sub deflection yoke 18 provided in the projection cathode ray tube 10 shown in FIG. The sub deflection yoke 18 forms a correction magnetic field near the rear end of the main deflection yoke 17 and appropriately deflects the electron beam in the horizontal direction and the vertical direction by the correction magnetic field, thereby forming an image on the projection screen 8. This is to correct the distortion. By correcting the distortion of the image using the sub-deflection yoke 8, it becomes possible to accurately align the images of each color on the projection screen 8 (registration correction).
[0010]
[Problems to be solved by the invention]
However, the conventional technique has the following problems. That is, when the distortion of the image on the projection screen 8 is corrected by using the sub deflection yoke 18, the correction magnetic field formed by the sub deflection yoke 18 extends to the front part of the main lens of the electron gun 19, so that the electron gun 19 The trajectory of the electron beam traveling inside toward the phosphor screen 15 is bent from the front part of the main lens. Then, since the electron beam passes through a position deviated from the center (main axis) of the main lens of the electron gun 19, the spot of the electron beam applied to the phosphor screen 15 is affected by the coma of the main lens and has a halo. , Resulting in an overall distorted shape. As a result, there is a problem that the quality of an image displayed on the face plate 14 of the projection cathode ray tube 10 and, consequently, the quality of an image displayed on the projection screen 8 are reduced.
[0011]
As a countermeasure, an electron gun 19 may be incorporated at a position sufficiently distant from the sub-deflection yoke 18 in order to avoid the influence of the correction magnetic field of the sub-deflection yoke 18. The other problem that the depth dimension of the cathode ray tube becomes longer arises.
[0012]
The present invention has been made in order to solve the above-mentioned problems, and an object of the present invention is to correct a distortion of an image on a projection screen without distorting a spot shape of an electron beam. An object of the present invention is to provide a cathode ray tube and a projection display device using the same.
[0013]
[Means for Solving the Problems]
The projection cathode ray tube according to the present invention includes an electron gun that forms a main lens for beam focusing on the trajectory of the electron beam emitted from the cathode, and a main deflection magnetic field that deflects the electron beam emitted from the electron gun. A main deflection yoke to be formed, a sub deflection yoke arranged near the rear end of the main deflection yoke to form a correction magnetic field for correcting image distortion on the projection screen, and a main lens formation portion. Are also arranged near the cathode, and have a coma aberration correcting deflection yoke for forming a coma aberration correcting magnetic field in a direction opposite to the correction magnetic field formed by the sub deflection yoke. Further, a projection type display device according to the present invention uses the projection cathode ray tube having the above configuration.
[0014]
In the projection cathode ray tube having the above configuration and a projection type display device using the same, when a correction magnetic field is formed by a sub deflection yoke in order to correct image distortion on a projection screen, the front stage of the main lens is used. A coma aberration correction magnetic field having a direction opposite to the above correction magnetic field is formed by a coma aberration correction deflection yoke. Thus, the electron beam emitted from the cathode is deflected in one direction by the coma aberration correcting magnetic field of the coma aberration correcting deflection yoke, and then is deflected in the other direction (the direction opposite to the one direction) by the correcting magnetic field of the sub deflection yoke. Be deflected. Therefore, by appropriately adjusting the coma aberration correction magnetic field and the magnetic field strength of the correction magnetic field, it is possible to correct the trajectory of the electron beam so as to pass through the center of the main lens.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, the same parts as those of the above-described related art will be denoted by the same reference numerals and described.
[0016]
FIG. 1 is a side sectional view schematically showing a configuration of a projection cathode ray tube according to an embodiment of the present invention. In FIG. 1, a main deflection yoke 17 forms a main deflection magnetic field (horizontal deflection magnetic field, vertical deflection magnetic field) for deflecting the electron beam emitted from the electron gun 19. It has a coil and a core. The horizontal deflection coil forms a horizontal deflection magnetic field at a position where the electron beam passes as one of the main deflection magnetic fields, and deflects the electron beam in the horizontal direction by the horizontal deflection magnetic field, thereby forming a screen of the cathode ray tube (phosphor). This scans the electron beam spot in the horizontal direction on the screen). The vertical deflection coil forms a vertical deflection magnetic field at a position where the electron beam passes as one of the main deflection magnetic fields, and deflects the electron beam in the vertical direction by the vertical deflection magnetic field, so that the electron beam is projected on the screen of the cathode ray tube. This scans the beam spot in the vertical direction (vertical scanning). The core is made of a magnetic material such as ferrite and has a function of increasing the strength of the horizontal deflection magnetic field generated by the horizontal deflection coil and the strength of the vertical deflection magnetic field generated by the vertical deflection coil.
[0017]
The electron gun 19 includes a cathode 21 serving as an electron emission source, and a plurality of grid electrodes G1 to G5 for controlling an amount, a moving speed, and the like of the electrons emitted from the cathode 21. The central axis of the electron gun 19 is arranged coaxially with the central axis of the cathode ray tube (hereinafter, Z axis). The electrons emitted from the cathode 21 are extracted by the potential difference between the cathode 21 and the first grid electrode G1, and are accelerated by the attraction force of the second grid electrode G2. On the other hand, the third grid electrode G3, the fourth grid electrode G4, and the fifth grid electrode G5 form an electrostatic lens by a potential difference between the respective electrodes. This electrostatic lens is formed as a beam focusing (focusing) main lens 22 for focusing an electron beam. The main lens 22 is formed on the trajectory of the electron beam from the cathode 21 toward the phosphor screen.
[0018]
Incidentally, FIG. 1 shows a state in which the main lens 22 is formed at the position of the fourth grid electrode G4, but the formation part of the main lens 22 in the Z-axis direction is in the form of the electron gun 19 (unipotential type). , Bipotential type, etc.) or the configuration (arrangement, number, etc.) of grid electrodes for electron beam control, and is not limited to the position of the fourth grid electrode G4. Further, the main lens 22 may be formed by a plurality of electrostatic lenses. For example, when an electrostatic lens is formed between the third grid electrode G3 and the fourth grid electrode G4 and between the fourth grid electrode G4 and the fifth grid electrode G5, the two electrostatic lenses are formed. One main lens is equivalently formed between the lenses (substantially in the middle) by combining the two electrostatic lenses.
[0019]
With respect to the main lens 22 formed by the electron gun 19 in this manner, a position closer to the cathode 21 than the portion where the main lens 22 is formed, more specifically, substantially the same as the first grid electrode G1 and the second grid electrode G2. A coma aberration correcting deflection yoke 23 is arranged at the position. The deflection yoke 23 for correcting coma aberration corrects coma aberration when the electron beam emitted from the cathode 21 passes through the main lens 22, in order to correct coma aberration in a direction opposite to a correction magnetic field formed by the sub deflection yoke 18. The sub-deflection yoke 18 is mounted on a neck portion for forming a correction magnetic field.
[0020]
More specifically, the sub deflection yoke 18 includes a horizontal deflection sub coil 18A for deflecting the electron beam in the horizontal direction and a vertical deflection sub coil 18B for deflecting the electron beam in the vertical direction. As shown in FIG. 2A, the sub-coil 18A is composed of a pair of coils connected (connected) in parallel to each other, and is wound in a toroidal shape on a pair of left and right arc-shaped magnetic cores 24, 24, respectively. ing. On the other hand, as shown in FIG. 2B, the sub-coil 18B is composed of a pair of coils connected (connected) in parallel to each other. It is wound in a shape. 2 (A) and 2 (B) show the case when viewed from the phosphor screen side.
[0021]
In the sub deflection yoke 18, when a correction current I1 is supplied to the pair of left and right subcoils 18A, 18A, the pair of subcoils 18A, 18A are, for example, in accordance with the direction (polarity) of the correction current I1 and the coil winding direction. An upward correction magnetic field is formed as shown in FIG. In this case, the electron beam E is deflected rightward by the upward correction magnetic field. Further, when the direction (polarity) of the correction current I1 flowing through the pair of sub-coils 18A, 18A is reversed from this state, the direction of the correction magnetic field is also reversed accordingly, so that the pair of sub-coils 18A, 18A generate the downward correction magnetic field. Form.
In this case, the electron beam E is deflected leftward by the downward correction magnetic field.
[0022]
When the correction current I2 flows through the pair of upper and lower sub-coils 18B, 18B, the pair of sub-coils 18A, 18A correspond to the direction (polarity) of the correction current I2 and the coil winding direction, for example, as shown in FIG. Thus, a correction magnetic field facing left is formed. In this case, the electron beam E is deflected upward by the leftward correction magnetic field. When the direction (polarity) of the correction current I2 flowing through the pair of sub-coils 18B, 18B is reversed from this state, the direction of the correction magnetic field is also reversed accordingly, so that the pair of sub-coils 18B, 18B Form. In this case, the electron beam E is deflected downward by the rightward correction magnetic field.
[0023]
On the other hand, the coma aberration correcting deflection yoke 23 is configured using a horizontal deflection coma correction coil 23A for deflecting the electron beam in the horizontal direction and a vertical deflection coma correction coil 23B for deflecting the electron beam in the vertical direction. Have been. As shown in FIG. 3A, the coma correction coil 23A is composed of a pair of coils connected (connected) in parallel to each other, and is wound in a toroidal shape on a pair of left and right arc-shaped magnetic cores 26, 26, respectively. Is lined. On the other hand, as shown in FIG. 3B, the top correction coil 23B is composed of a pair of coils connected (connected) in parallel to each other, and includes a pair of upper and lower arc-shaped magnetic cores 27,27. Each is wound in a toroidal shape. FIGS. 3A and 3B show the case when viewed from the phosphor screen side.
[0024]
In the coma aberration correcting deflection yoke 23, when a correction current I3 is supplied to the pair of left and right coma correction coils 23A, 23A, a pair of coma corrections are made in accordance with the direction (polarity) of the correction current I3 and the coil winding direction. The coils 23A, 23A form a downward coma aberration correction magnetic field, for example, as shown in FIG. In this case, the electron beam E is deflected leftward by the downward coma aberration correction magnetic field. When the direction (polarity) of the correction current I3 flowing through the pair of coma correction coils 23A, 23A is reversed from this state, the direction of the coma aberration correction magnetic field is also reversed accordingly, so that the pair of coma correction coils 23A, 23A Forms an upward coma aberration correction magnetic field. In this case, the electron beam E is deflected rightward by the upward coma aberration correction magnetic field.
[0025]
When a correction current I4 is supplied to the pair of upper and lower frame correction coils 23B, 23B, the pair of frame correction coils 23B, 23B correspond to the direction (polarity) of the correction current I4 and the coil winding direction, for example, as shown in FIG. A rightward coma aberration correction magnetic field is formed as shown in FIG. In this case, the electron beam E is deflected downward by the rightward coma aberration correction magnetic field. When the direction (polarity) of the correction current I4 flowing through the pair of coma correction coils 23B, 23B is reversed from this state, the direction of the coma aberration correction magnetic field is also reversed accordingly, so that the pair of coma correction coils 23B, 23B Form a leftward coma aberration correction magnetic field. In this case, the electron beam E is deflected upward by the leftward coma aberration correction magnetic field.
[0026]
In the sub deflection yoke 18 and the coma aberration correcting deflection yoke 23 configured as described above, the winding direction of the sub coil 18A and the winding direction of the coma correction coil 23A are opposite to each other, and the winding of the sub coil 18B is opposite. The direction and the winding direction of the frame correction coil 23B are also opposite to each other. Therefore, when the correction currents I1 and I3 having the same phase waveform are supplied to the sub coil 18A and the coma correction coil 23A, the coma correction coil 23A always generates a magnetic field in the opposite direction to the magnetic field formed by the sub coil 18A. Similarly, when the correction currents I2 and I4 having the same phase waveform are respectively supplied to the sub coil 18B and the coma correction coil 23B, the coma correction coil 23B always forms a magnetic field in the opposite direction to the magnetic field formed by the sub coil 18B. .
[0027]
Further, the intensity of the magnetic field formed by the coma correction coil 23A is weaker than the magnetic field formed by the sub coil 18A, and the intensity of the magnetic field formed by the coma correction coil 23B is weaker than the magnetic field formed by the sub coil 18B. The reason for setting (adjusting) the magnetic field strength under such a condition is that the coma aberration correcting deflection yoke 23 is disposed on the stage (cathode side) of the electron gun 19 before the sub deflection yoke 18 in the Z-axis direction. Since the moving speed of the electron beam on the first stage is lower than the moving speed of the electron beam on the second stage, the coma aberration correcting deflection yoke 23 can deflect the electron beam with higher deflection sensitivity than the sub deflection yoke 18. is there. Incidentally, the intensity of the magnetic field generated by each coil can be arbitrarily adjusted according to the thickness of the wire of the coil, the number of turns, the dimensions of the magnetic core, and the like.
[0028]
In the projection cathode ray tube having the above-described configuration, correction currents I1 and I2 (see FIG. 2) are supplied to the sub-coils 18A and 18B of the sub-deflection yoke 18, respectively, and supplied to the coma correction coils 23A and 23B of the deflection yoke 23 for coma aberration correction. When the correction currents I3 and I4 (see FIG. 3) are supplied, as shown in FIG. 4, the sub-deflection yoke 18 forms a correction magnetic field φH1, and the coma aberration correction deflection yoke 23 generates a coma in the opposite direction to the correction magnetic field φH1. An aberration correction magnetic field φH2 is formed.
[0029]
That is, when the sub-coil 18A forms an upward magnetic field, the top correction coil 23A forms a downward magnetic field, and when the sub-coil 18A forms a downward magnetic field, the top correction coil 23B generates an upward magnetic field. When the subcoil 18B forms a leftward magnetic field, the coma correction coil 23B forms a rightward magnetic field, and when the subcoil 18B forms a rightward magnetic field, the coma correction coil 23B forms a leftward magnetic field. Accordingly, the correction magnetic field φH1 formed by the sub deflection yoke 18 and the coma aberration correction magnetic field φH2 formed by the coma aberration correcting deflection yoke 23 have respective distribution shapes as shown in FIG.
[0030]
As a result, the direction of deflection of the electron beam by the sub deflection yoke 18 and the direction of deflection of the electron beam by the deflection yoke 23 for coma aberration correction are opposite to each other. The emitted electron beam is once deflected away from the Z-axis by the coma aberration correction magnetic field φH2, and then deflected toward the Z-axis by the correction magnetic field φH1. Therefore, at the portion where the main lens 22 is formed, the trajectory of the electron beam can be corrected so as to pass through the center of the main lens 22.
[0031]
As a result, when the electron beam is deflected by the correction magnetic field φH1 of the sub-deflection yoke 18 as in the related art, the beam trajectory K1 is shifted from the center of the main lens 22 and is affected by coma. When the electron beam is deflected by the correction magnetic field φH1 of the sub deflection yoke 18 and the coma aberration correction magnetic field φH2 of the coma aberration correcting deflection yoke 23 as in the embodiment, the beam trajectory K2 is made to coincide with the center of the main lens 22, The influence of aberration can be suppressed. Therefore, when the spot shape of the electron beam on the phosphor screen is compared, the spot of the electron beam E1 moved along the beam trajectory K1 becomes distorted by halo, but moves along the beam trajectory K2. The spot of the electron beam E2 becomes a circular shape (almost a perfect circle) without distortion.
[0032]
Accordingly, in the configuration including the deflection yoke 23 for coma aberration correction, when the distortion of the image on the projection screen is corrected by the correction magnetic field φH1 of the sub deflection yoke 18, when the electron beam is deflected by the correction magnetic field φH1. A coma aberration correcting magnetic field φH2 is formed on the front stage side of the main lens 22 so that the electron beam passes through the center of the main lens 22, and the intensity of the coma aberration correcting magnetic field φH2 is appropriately adjusted. It is possible to correct the distortion of the image on the projection screen without distorting the spot shape.
[0033]
The correction currents I3, I4 supplied to the coma correction coils 23A, 23B of the deflection yoke 23 for coma aberration correction have the same phase waveform as the correction currents I1, I2 supplied to the sub-coils 18A, 18B of the sub-deflection yoke 18. Therefore, the sub-deflection yoke 18 and the coma aberration correcting deflection yoke 23 can be used in common as the correction circuit for supplying the correction current. Thus, in order to eliminate the distortion of the spot shape in the current projection cathode ray tube, it is possible to substantially cope with it only by adding the coma aberration correcting deflection yoke 23, so that it is possible to introduce it at low cost.
[0034]
In the above embodiment, the winding directions of the sub-coil 18A and the coma correction coil 23A are set to be opposite to each other, and the correction currents I1 and I3 having the same phase waveform are supplied to the respective coils 18A and 23A. The magnetic field formed by the sub-coil 18A and the magnetic field formed by the coma correction coil 23A are opposite to each other, but the present invention is not limited to this, and the winding direction of the sub-coil 18A and the winding By supplying the correction currents I1 and I3 having waveforms of opposite phases to the coils 18A and 23A in the same direction, the magnetic field formed by the sub-coil 18A and the magnetic field formed by the coma correction coil 23A are similar to the above. May be opposite to each other. The winding directions of the sub-coil 18B and the coma correction coil 23B are set to the same direction, and correction currents I2 and I4 having waveforms opposite to each other are supplied to the coils 18B and 23B. And the magnetic field formed by the coma correction coil 23B may be opposite to each other. In this case, the phases of the correction currents I1 and I3 flowing through the coils 18A and 23A are inverted by simply changing the connection relationship (connection) between the terminals of the correction circuit supplying the correction current and the terminals connected to the coils, and the coils 18B , And 23B, the phases of the correction currents I2 and I4 can be inverted, so that the correction circuit can be shared in the same manner as described above.
[0035]
Further, as a configuration of the sub deflection yoke 18, a circular ring-shaped magnetic core is adopted, and a sub coil 18A is wound in a toroidal shape on each of the left and right sides of the magnetic core. The sub-coil 18B may be wound in a toroidal shape. Similarly, as the configuration of the coma aberration correcting deflection yoke 23, a circular ring-shaped magnetic core is adopted, and a coma correction coil 23A is wound on each of the left and right sides of the magnetic core in a toroidal shape. A frame correction coil 23B may be wound in a toroidal shape above and below the body core. Further, the sub-coils 18A and 18B and the coma correction coils 23A and 23B are not limited to toroidal windings, but may be saddle-shaped windings.
[0036]
【The invention's effect】
As described above, according to the present invention, the trajectory of the electron beam is corrected so as to pass through the center of the main lens by forming the coma aberration correction magnetic field by the deflection yoke for coma aberration correction on the front side of the main lens. Since the influence of the core aberration can be suppressed, the distortion of the image on the projection screen can be appropriately corrected without distorting the spot shape of the electron beam. As a result, it is possible to improve the quality of the display image projected on the projection screen.
[Brief description of the drawings]
FIG. 1 is a side sectional view showing a configuration of a projection cathode ray tube according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of a sub deflection yoke.
FIG. 3 is a diagram illustrating a configuration of a deflection yoke for coma aberration correction.
FIG. 4 is a diagram showing an operation state of the projection cathode ray tube according to the embodiment of the present invention.
FIG. 5 is a diagram illustrating a configuration example of a projection display device.
FIG. 6 is a cross-sectional view showing a configuration example of a projection cathode ray tube.
FIG. 7 is a diagram showing a distortion shape of an image on a projection screen.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Projection display apparatus, 10 ... Projection cathode ray tube, 17 ... Main deflection yoke, 18 ... Sub deflection yoke, 18A, 18B ... Sub coil, 19 ... Electron gun, 21 ... Cathode, 22 ... Main lens, 23 ... Coma aberration Correction deflection yoke, 23A, 23B ... frame correction coil

Claims (2)

An electron gun that forms a main lens for beam focusing on the trajectory of the electron beam emitted from the cathode,
A main deflection yoke for forming a main deflection magnetic field for deflecting the electron beam emitted from the electron gun,
A sub-deflection yoke arranged near the rear end of the main deflection yoke and forming a correction magnetic field for correcting image distortion on the projection screen;
A coma aberration correcting deflection yoke which is arranged closer to the cathode than the main lens forming portion and forms a coma aberration correcting magnetic field in a direction opposite to the correction magnetic field formed by the sub deflection yoke. Projection cathode ray tube. An electron gun that forms a main lens for beam focusing on the trajectory of the electron beam emitted from the cathode,
A main deflection yoke for forming a main deflection magnetic field for deflecting the electron beam emitted from the electron gun,
A sub-deflection yoke arranged near the rear end of the main deflection yoke and forming a correction magnetic field for correcting image distortion on the projection screen;
A projection cathode ray tube including a coma aberration correcting deflection yoke that is arranged closer to the cathode than the main lens forming portion and forms a coma aberration correcting magnetic field in a direction opposite to the correction magnetic field formed by the sub deflection yoke. A projection display device characterized by using:

Images