MXPA06007074A - Hdtv crt display having optimized tube geometry, yoke field and gun orientation - Google Patents

Abstract

A cathode ray tube (1) has a faceplate panel (3) with a short axis and a long axis. The faceplate panel has a display screen on the inside of the panel and the panel extends back to a funnel (5) which houses an electron gun system within an integral neck (4). The electron gun system produces co-planar beams arranged in a linear array which is parallel to a short axis of the screen (12). A deflection system (14) is positioned over the neck of the funnel for applying electromagnetic control fields to electron beams emanating from the electron gun system directed toward the screen. The deflection system has a first deflection coil system for generating a substantially barrel shaped magnetic field for deflecting the beams in the direction of the long axis and a second deflection coil system for generating a substantially pincushion magnetic field for deflecting the beams in the direction of the short axis. At least one of the deflection coil systems generates a misconvergence along at least one of the axes parallel to the direction of the co-planar beam. Coils (16) for generating a quadrupolar magnetic field are coupled to the deflection coil systems for correcting misconvergence.

Description

DEPLOYMENT OF CATHODIC RAYS PIPE FOR HIGH DEFINITION TELEVISION THAT HAS A PIPE GEOMETRY, YOUTH FIELD AND OPTIMIZED GUN ORIENTATION FIELD OF THE INVENTION The invention relates to a cathode ray tube (CRT) deployment and more in particular, to a deployment having yoke fields, gun orientation and improved related components for use in a high-ratio deployment. dimensional for a high definition television (HDTV).

BACKGROUND OF THE INVENTION With the continuous advances in television technology, the images of a high definition television (HDTV) are transmitted through selected channels. It is expected that the transmission of HDTV images will continue to improve and the need for deployments with the ability to receive and display HDTV images will follow this trend. Along with this development, flat screens with a high dimensional relationship and improved visual resolution performance characteristics continue to be in demand. Therefore, there is a need to provide a CRT display that has improved visual resolution performance on a high dimensional aspect ratio screen with the ability to display HDTV images.

Improved point performance, such that the size and shape of the point are uniform across the entire screen is desirable for purposes of improving the performance of visual resolution. For this purpose, a dynamic approach is applied. Controlling and optimizing point performance is increasingly difficult with high dimensional aspect screens, such as a 16: 9 aspect ratio display. Attempts have been made to improve the performance of the point by increasing the angle of deflection and reducing the shot, that is to reduce the distance between the gun and the screen. Figure 1 shows the basic geometric relationship between the firing angle and the deflection angle in a typical CRT. Increasing the angle A of deflection is favorable since it reduces the shot and allows the production of a shorter CRT and finally, a thinner television set. As the deflection angle is increased, the shot decreases and the point size decreases favorably in a non-linear relationship. The relationship between the point size and the shot can be determined mathematically by the following equation: Point size = Shot 1 4 where the factor 1.4 is an approximation that takes into account the effects of amplification and space loading over the useful range of the current ray. When considering this relationship, it can be observed that by increasing the deflection angle and thus reducing the central shot, for example, from 413 mm to 313 mm or 24% of the point size, it is reduced to 32% at the center of the screen and it reduces 23% in the corners. Increasing the angle of deflection in these deployments presents problems of obliquity. This problem is especially evident in CRTs that have a standard gun orientation, that is, guns that have been aligned horizontally along the major axis of the screen. The obliquity is the effect of a beam that intercepts the screen at an oblique angle, which causes the point to elongate in the radial direction. As the obliquity is increased, a point that is generally circular in the center of the screen becomes radially more oblong or elongated as it moves toward the edges of the screen. Based on this geometric relationship, in a high dimensional ratio screen, for example, 16x9, the point is more elongated at the edges of the major axis and at the corners. These obliquity effects cause the point to grow radially by a Ssradial factor defined by the following equation: Ssradial = Ssnormal / cos (A) where a is the deflection angle measured from De to De as shown in Figure 1 and Ssnormal It is the point size without the obliquity effects. In addition to the obliquity effects described in Figure 1, the shape of the point is also compromised by the deflection effects of the yoke in CRT of self-convergence that have a horizontal gun orientation. To achieve self-convergence, the horizontal yoke field that has a cushion-shaped field while the vertical yoke field has a barrel-shaped field. These yoke fields cause a horizontal elongation of the point. This elongation adds oblique effects that also increase the distortion of the point in 3/9 and in the corner positions on the screen. Several attempts have been made to solve these problems of distortion and obliquity of the point. For example, U.S. Patent No. 5,170,102 describes a CRT with a vertical orientation of an electron gun, so that the plane in which the non-deflected rays are located is parallel to the short axis of the display screen. This deflection system is connected to a signal generator to scan the display screen in a frame having a plurality of lines oriented along the short access of the display screen. The deflection system has a first group of coils to generate a deflection field essentially in the form of a cushion to deflect the rays in the direction of the short axis of the deployment screen and a second group of coils to generate a deflection field essentially with barrel shape, to deflect the rays in the direction of the long axis of the display screen. The deflection effects of the system yoke usually distort the points by lengthening them vertically. This vertical elongation compensates for the obliquity effects, which reduces the distortion of the point in 3/9 and in the corner positions of the screen. The barrel-shaped field required to achieve auto-convergence at 3/9 screen locations, however, adds resulting obliquity at a vertical elongated point in 3/9 and at corner locations, as shown in Figure 10 of U.S. Patent No. 5,170,102. Although some improvements have been made in guiding the electron guns along the vertical axis or less in a convergence system, point distortion remains problematic in 3/9 and in the corner locations of the screen. Therefore, it is desirable to improve dot shape and visual resolution in these applications, especially along the sides and corners of the screen.

BRIEF DESCRIPTION OF THE INVENTION The invention provides a cathode ray tube having a clamping plate panel with a short axis and a long axis. The fastening plate panel has a display screen on the inside of the panel and the panel extends rearwardly to a funnel housing an electron gun system, inside an integrated neck. The electron gun system produces co-planar rays arranged in a linear array that is parallel to the short axis of the screen. A deflection system is placed on the neck of the funnel to apply fields of electromagnetic control for the electron beams emanating from the electron gun system directed towards the screen. The deflection system has a first deflection coil system for generating an essentially barrel-shaped magnetic field to deflect the rays in the long axis direction and a second deflection coil system for generating a magnetic field essentially in the form of a cushion to deflect the rays in the direction of the short axis. Therefore one of the deflection coil systems generates a bad convergence along at least one of the axes parallel to the direction of the coplanar beam. The coils to generate a four pole magnetic field are coupled with the coil deflection systems to correct the bad convergence.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described by way of example with reference to the accompanying Figures, in which: Figure 1 is a diagram showing the basic geometric relationship between the firing and deflection angle in a typical CRT. Figure 2 is a cross-sectional, diagrammatic view of a CRT in accordance with the present invention. Figure 3 is a diagram of the CRT screen illustrating a bad convergence pattern of the invention; and Figure 4 is a diagram showing the optimization of the dot shape according to the invention.

DETAILED DESCRIPTION OF THE INVENTION Figure 2 shows a cathode ray tube 1 (CRT), for example, a wide screen tube W76 having a glass envelope 2 comprising a rectangular clamping plate panel 3 and a tubular neck 4 funnel 5. The funnel 5 has an internal conductive coating (not shown) extending from the anode button 6 towards the fastening plate panel 3 and towards the neck 4. The fastening plate panel 3 comprises a display holding plate 8 and a flange or peripheral side wall 9, which is sealed with the funnel 5 by a glass covering 7. A three-color phosphor screen 12 is supported by the inner surface of the panel 3 of the clamping plate. Screen 12 is a line screen with the phosphor lines arranged in thirds, each of the thirds includes a phosphor line of each of the three colors. A mask assembly 10 is removably mounted in a predetermined separate relationship with the screen 12. An electron gun 13, shown schematically by the dashed lines of Figure 2, is mounted centrally within the neck 4 to generate and direct three in-line direct electron beams, one central beam and two lateral or external beams, along converging paths through a tension mask structure assembly 10 on the screen 12. The electron gun 13 consists of three pistols oriented vertically, directing a beam of electrons for each of the three colors, red, green and blue. The red, green and blue pistols are arranged in a linear array extended parallel to the minor axis of the screen 12. The phosphor lines of the screen 12 are arranged in equal lengths generally parallel to the major axis of the screen 12. Of the same In this manner, the mask 30 has multiple extended elongate slots generally parallel to the major axis of the screen 12. Those skilled in the art will understand that various types of shadow mask or tension assemblies formed can be used., well known in the art. The CRT 1 is designed to be used with an external magnetic deflection system having a yoke 14 shown near the funnel-to-neck junction. When activated, the yoke 14 subjects three beams to the magnetic fields which cause the rays to be scattered vertically and horizontally in a rectangular frame on the screen 12. The yoke 14 and the effects of the yoke will now be described with more detail The yoke 14 is positioned near the funnel-to-neck junction, as shown in Figure 2 and in this embodiment, it is wound to apply a horizontal deflection yoke field, which has an essentially barrel shape and a yoke field vertical that has an essentially cushion shape. The yoke field in the form of a vertical cushion is generated by a first deflection coil system to be wound on the yoke. The yoke field with horizontal shape is generated by a second deflection coil system also wound on the yoke, which is electrically isolated from the first deflection coil system. The winding of the deflection coil systems is achieved with well-known techniques. Yoke fields affect the convergence of the beam and the shape of the point. In the prior art, these fields, in general, were adjusted to achieve the self-convergence of the rays. Instead of adjusting for self-convergence, in the invention, the shape of the horizontal barrel field is adjusted, for example, is reduced, to offer an optimized point shape on the sides of the screen. The barrel shape of the field is reduced to an almost round dot shape optimized in 3/9 and at the corners of the screen. This adjustment in the shape of the field, which results in an improved form of the point, compromises the auto-convergence, which can cause a bad convergence in certain locations on the screen. Figure 3 shows a full screen diagram illustrating the poor convergence resulting from the reduced barrel shape of the field. For example, when the barrel field is reduced as described above to reach an optimized point in 3/9 and the corner locations, the rays converge on the sides. Over-convergence, as used here, describes a condition where the red and blue rays have crossed over each other before landing on the screen. The amount of over-convergence is a function of beam deflection. Therefore, as shown in Figure 3, the resulting pattern converges to the center while the pattern has an orientation of poor convergence on the sides. Assuming that the orientation of the gun from the top to the bottom is red, green and blue, it can be seen in Figure 3, that over-convergence caused the rays to land in a blue, green, red convergence pattern on the sides of the screen. The resulting convergence on the sides of the screen in this example was measured to be approximately 15 millimeters. Other CRT designs that have different geometries and yoke field distributions may result in greater or lesser convergence, for example, within the range of 5 to 35 millimeters. The correction of the bad convergence or over-convergence that resulted from the yoke effect described above is achieved by the addition of four-pole coils 16. The poor convergence of the yoke effect at locations along the screen 12 is corrected dynamically by the four-pole coils 16 located on the gun side of the yoke 14. The four-pole coils 16 are fixed on the yoke 14 or can be applied, alternatively, on the neck and has four poles oriented at angles of approximately 90 °, one relative to the other as is known in the art. The adjacent poles have an alternating polarity and the orientation of the poles is at 45 ° from the tube axes, so that the resulting magnetic field moves the external rays (red and blue) in a vertical direction to provide correction for the pattern of bad convergence shown in Figure 3. The four-pole coils 16 are located behind the yoke 14, so that they remain approximately or close to the point of dynamic astigmatism of the guns 13. The four-pole coils 16 are dynamically controlled to create a correction field for adjusting the poor convergence at locations on the screen. The four-pole coils 16, in this embodiment, are activated synchronized with the horizontal deflection. The magnitude of the four-pole activation waveform is selected to correct the above-described convergence. In this mode, the waveform has an approximately parabolic shape. The guns 13 in this mode have an electrostatic dynamic focus correction (or astigmatism) in order to achieve optimal focus in the vertical and horizontal directions in each of the three rays. This correction of electrostatic dynamic astigmatism is performed separately in each beam and allows the correction of voltage differences from horizontal to vertical focus without affecting convergence. Although the four-pole coils 16 also affect the focus of the beam, its location near the point of dynamic astigmatism of the gun allows this effect to be corrected by adjusting the electrostatic dynamic astigmatism voltage of the gun without affecting the shape of the resulting point. This results in a favorable effect of having the ability to correct the bad convergence in selected locations on the screen without affecting the shape of the point. This allows to improve the shape of the point by the design of the yoke field and any resulting poor convergence can be corrected by the dynamically activated four-pole coils 16. Figure 4 illustrates the improvement in shape and size of the point achievable with this invention. Figure 4 shows a screen quadrant of a CRT W76 with a dimensional ratio of 16: 9 and a deflection angle of 120 °. The points shown on the dotted lines represent the effects of the shot and obliquity indicated in a round center point. The optimized points obtained with the methods of this invention are shown with solid lines. Major improvements in the size and shape of the point can be seen on the sides and corners of the screen. The experimental results of the system according to the present invention are also shown in Table 1 below, where H represents the horizontal dimension of each point and V represents the vertical dimension of each normalized point at the center point. This table shows the cumulative effect of gun orientation, yoke field effects and four-pole coils dynamically controlled with a dynamic applied astigmatism correction compared to traditional horizontal line gun CRTs. TABLE 1 Column two represents the CRT with standard horizontal orientation of the prior art with self-converging rays, while column three represents the results of a CRT according to the invention, where the rays are dynamically controlled from convergence. Although the point shape looks a bit compromised in the 6/12 locations, it is much improved in 3/9 and in the corner locations. Therefore, the invention advantageously provides a more uniform point shape across the screen, which improves the performance of the visual resolution. The foregoing illustrates some of the possibilities for practicing the invention. Many other modalities are possible within the scope and spirit of the invention. For example, the vertical deflection field can be altered to improve the point shape in other screen locations, for example, in the 6/12 locations that result in poor convergence in these locations. This poor convergence can be corrected with the use of the methods of the invention to activate the four-pole coils with a waveform synchronized with the vertical deflection. Horizontal and vertical combinations can be used. The embodiments may also include various combinations of the following characteristics: the coils for generating a magnetic field to be four-pole magnetic fields, the deflection system comprising a yoke, the coils arranged at approximately 90 degrees one from the other, and they are placed approximately at the dynamic astigmatism correction point of the electron pistol system, the coils are controlled dynamically, the coils are activated at the horizontal deflection speed, the bad convergence is an over-convergence for the external rays of electrons, the over-convergence is in the range of 5-35 millimeters, the bad convergence caused by the deflection system increases with the horizontal deflection, and the bad convergence can be corrected with the four-pole coils activated in sync with the deflection horizontal, and the cathode ray tube has a screen aspect ratio of 16: 9. Therefore, it is intended that the foregoing description be considered as illustrative rather than limiting, and the scope of the invention is determined by the appended claims, along with the wide range of equivalents.

Claims (17)

1. A cathode ray tube having a clamping plate panel with a short axis and a long axis, the clamping plate panel has a display screen on the inside of the panel and the panel extends rearwardly to a funnel housing the electron gun system inside an integrated neck to produce co-planar rays, the electron gun system is arranged in a linear array that is parallel to the short axis of the screen; The cathode ray tube is characterized in that it comprises: a deflection system placed on the neck of the funnel to apply electromagnetic control fields for the electron beams originating from the electron gun system directed towards the screen, the deflection system has : a first deflection coil system for generating a magnetic field essentially barrel shaped to deflect the rays in the long axis direction; a second deflection coil system for generating a cushion magnetic field to deflect the rays in the direction of the short axis; at least one of the deflection coil systems generates a poor convergence along at least one of the axes parallel to the direction of the co-planar beam; and coils to generate a magnetic field, the coils are coupled with the deflection coil systems to generate a correction field to correct the bad convergence. The cathode ray tube according to claim 1, characterized in that the coils are four-pole coils for generating a four-pole magnetic field. 3. The cathode ray tube according to claim 2, characterized in that the deflection system comprises a yoke. 4. The cathode ray tube according to claim 3, characterized in that the coils are arranged at approximately 90 degrees from each other and placed approximately at the dynamic astigmatism correction point of the electron gun system. 5. The cathode ray tube according to claim 4, characterized in that the coils are controlled dynamically. 6. The cathode ray tube according to claim 5, characterized in that the coils are activated at the horizontal deflection speed. 7. The cathode ray tube according to claim 2, characterized in that the bad convergence is an external overconvergence to the electron beams. 8. The cathode ray tube according to claim 7, characterized in that the overconvergence is within the range of 5-35 millimeters. 9. The cathode ray tube according to claim 2, characterized in that the poor convergence caused by the deflection system increases with the horizontal deflection. 10. The cathode ray tube according to claim 9, characterized in that the bad convergence is corrected with four-pole coils activated in synchrony with the horizontal deflection. 11. The cathode ray tube according to claim 10, characterized in that the aspect ratio of the screen is 16: 9. 1

2. A deflection apparatus characterized in that it comprises: a cathode ray tube having a clamping plate panel with a short axis and a long axis, the clamping plate panel having a display screen on the front of the panel and the panel extends back towards a funnel that houses the electron gun system inside an integrated neck to produce co-planar rays, the electron gun system is arranged in a linear array that is parallel to the short axis of the screen; a horizontal deflection coil for generating a horizontal deflection field having a non-uniformity field essentially in the form of a barrel, for scattering the rays in the direction of the long axis and a vertical deflection coil for generating a vertical deflection field having a non-uniformity of field essentially shaped as a cushion to scatter the rays in the direction of the short axis, the field non-uniformity of at least one of the deflection fields is selected to provide the beam-point correction instead of providing another error correction of bad convergence; and a third deflection coil for generating a third deflection field having a field non-uniformity selected to correct at least a portion of the bad convergence error that was left uncorrected by at least one deflection field. The deflection apparatus according to claim 12, characterized in that the third deflection coil generates a four-pole magnetic field. The deflection apparatus according to claim 12, characterized in that it further comprises a fourth deflection coil, wherein the third and fourth deflection coils are arranged at approximately 90 degrees one from the other and placed approximately at the correction point of the deflection. dynamic astigmatism of the electron gun system. The deflection apparatus according to claim 12, characterized in that the third deflection coil is controlled dynamically. The deflection apparatus according to claim 12, characterized in that the third deflection coil is activated at the horizontal deflection speed. 17. The deflection apparatus according to claim 12, characterized in that the bad convergence error is an external overconvergence to the electron beams.