TW594825B - Electron gun for cathode ray tubes - Google Patents

Abstract

Electron gun for cathode-ray tubes, comprising at least one cathode based on field-effect microemitters, the microbeams of which converge on a region in such a way that the two points of convergence of the microbeams in the horizontal and vertical directions are two separate points Ox, Oy in this region.

Description

594825 玖 发明, description of the invention (the description of the invention should state: the technical field to which the invention belongs, the prior art, the content, the embodiments and the simple description of the drawings) _ The present invention relates to the electronic grab for cathode ray tubes, which is incorporated based on- Cathode system, one of the cold-emission type micro-emitters, especially regarding the electronic grab structure suitable for this type of cathode ray tube. · A traditional electronic snare uses one or more hot filament hot cathodes, with a continuous electrode behind the cathode to form an electron beam, and then permanently focuses on the screen of the tube, and the displayed image is reproduced thereon. · The meaning of continuous electrode is that the length of the electron grab is quite long, and it is a factor that determines the final path of the tube. Because the reflection angle of the electron beam of the screen of the scanning tube actually remains at 110 degrees, this depth increases rapidly with the size of the diagonal of the screen, and currently consumers tend to choose a screen with a larger but smallest depth. In addition, the electron grab of the cathode ray tube must be able to have the shape of the waypoint with the least distortion on the entire surface of the image screen. This requirement is difficult to achieve when the social network wants to reproduce the color image, because the three beams output by the electronic grabbing must converge on the screen. Leaving the center of the screen, convergence is achieved by a magnetic deflection system, also known as a deflector, whose deflection magnetic field is astigmatism. The astigmatism of the deflector magnetic field causes distortion of the beam passing through the action area, thus distorting the shape of the waypoint of the beam on the image. As pointed out in U.S. Patent No. US 5,430,349, different methods can be used in hot cathode electronic grabbing to correct the beam distortion caused by the astigmatic deflection field, such as a device for dynamically controlling astigmatism. However, these devices need to introduce additional structures in the electronic grabbing and conflict with the shortening of the electronic grabbing. -The purpose of the present invention is to obtain a shorter electronic grab, i.e., along its main axis-594825

(2) The length is small and the special structure of a cathode may provide additional parameters to correct the astigmatism effect of the deflection field on the electron beam; the effect of correcting the astigmatism of the deflection field is to establish a beam in the cathode, the astigmatism The effect can evenly compensate the astigmatism of the deflection field. To this end, the electronic grab of the present invention includes:-a first bias electrode, also known as a cathode conductor,-at least one cold-emitting micro-emitter array, which is placed on the cathode conductor

The micro-emitters are electrically connected to the cathode conductor to emit several electron microbeams by the field effect, an extraction electrode is placed on the cathode conductor, and the extraction electrode includes a pore region located in the Above the micro-emitter array,-a collimating electrode to reduce the emission angle of the micro-beams, and-at least one focusing electrode, characterized in that the electron grabs-means for converging the micro-beam to In the virtual image area behind the cathode on the opposite side, the #convergence point of the #microbeam in the vertical and water directions is two independent points in the virtual image area 0x '〇y.

The better healing and many advantages of the present invention will be obtained in the following description, among which:

Fig. 1 shows a cross-section of an electron beam forming area output by a conventional hot cathode. Fig. 2 is a cross-sectional view of a field-emission micro-tip cathode based on conventional techniques. Fig. 3 illustrates the principle of the present invention in perspective. 4b, 4c, and 4d represent the pole structure of the present invention in cross section; and (4) 594825

The microtip 12 is biased. The cathode conductor is placed on the substrate 2 and is usually made of glass to provide the mechanical strength of the cathode. A resistive layer 7 can be excellently deposited between the microtips and the cathode conductor 5 to improve the emission uniformity from each microtip. A second electrode, also referred to as a capture gate 10, is placed on the cathode conductor 5, which is insulated from it by an electrically insulating layer 8. There is a gap on each microtip of the capture gate. When the voltage is positive relative to the voltage of the cathode conductor

When a voltage of tens to hundreds of volts is applied to the gate, the latter emits an electron microbeam 20 which incorporates the cathode into one of the electrons and the anode accelerates the emitted electrons at a voltage of thousands to tens of thousands of volts. In a standard configuration, the capture gate covers the cathode conductor, except for the pores above the microemitter. In this configuration, the beam 20 is orthogonal to the plane of the acquisition gate at an angle of about 30 degrees.

In order to reduce this emission angle, it is known that a microbeam collimating electrode can be placed in the path of the microbeam, as shown in Fig. 4c, which shows a transmitting element 12 and an extraction electrode 10 and a quasi electrode 21. A deceleration electrode 22 can be placed between the electrodes 10 and 21 in order to decelerate the emitted electrons and to better align the microbeam 20, and the dispersion angle can also be lowered to less than 1 degree, preferably 0.3. degree. In order to fabricate the cathode with a single element 2 3, the electrode can be fabricated on the insulating layer 24 by depositing metal. The principle of the present invention is illustrated in FIG. 3. A micro-emitter cathode, such as cathode 23, radiates a plurality of beams 26. Viewed from the χζ plane of the cathode symmetry, the microbeam constitutes an emission cone, and its imaginary vertices form a practical point-like region 0χ is located above the 2 axis and behind the cathode, its vertex angle is 0X. Viewed in the symmetric γζ plane, the microbeam forms a transmitting cone with a vertex angle y, and its imaginary vertices form a practical point shape -9-

Area 594825 is on the Z axis and behind the cathode. The microbeam emission cone in the plane containing the z-axis appears to diffuse from the imaginary vertices bounded by the region 40 and points 0x and 0y. As illustrated in the example of Fig. 3, point 0x is closer to the cathode than point 0y, which means that Θχ is greater than. Therefore, in a plane perpendicular to the propagation of the microbeam, the total beam output of the cathode 23 appears to be flat longer than a beam parallel to 0χ. In the first embodiment of the present invention, as shown in FIGS. 4a, 4b, 4c and 4d, the beamforming area of the conventional art electronic grabbing is shown in FIG. 1. The cathode 23 has been replaced by 'cathode 23 which contains multiple types of emission described above. body. The cathode 23 constitutes an emission matrix in the shape of a dish. Its axis coincides with the main axis of the electron grabber. Its surface is curved so that the total electron beam 32 output by the cathode is composed of microbeams emitted by micro-emitters distributed on the surface. The apex of the 40 converging microbeam 26 is located behind the cathode, and this area constitutes the virtual crossover of this example. Considering Fig. 4b, the cutting plane containing the Z axis of propagation and the edge of the emission area of the substantially circular cathode 23 are taken. Vertically and more into the propagation axis of the cathode total beam output. As shown in Fig. 4a, the cathode is placed in the electron hole at the entrance of the first electrode G3 of the focusing lens. The wide aperture of the first focusing electrode makes it possible to use a cathode 23 having an emission portion having a diameter close to that of G3. It is known that there is no interaction between the two electrostatic lenses in electronic grabbing, and the distance between the two must be at least 1.5 times larger than the maximum diameter of the two lenses. In the cathode-ray tube electron pick-up ', the maximum diameter of the focal lens is about 5 mm. Therefore, according to the cathode of the present invention, its diameter may be 1 mm. In order to have the same beam conditions as the conventional structure incorporating a hot cathode, that is, when the current is 5 m A, the wave -10- 594825

(6) The beam has a 3 at the entrance of the lens and a propagation axis. And 5. Of diffusion angle ae. To achieve this, the cathode 23 is placed 7-10 mm away from the focusing lens. As a result, the electrons are shortened by about 20-23 mm, and the total length of the electrons is about 80 mm. . . Figure 4d illustrates the method of introducing an astigmatic beam of transmitting cathodes. The astigmatism phenomenon is intended to compensate for the astigmatism caused by the deflection field. For this reason, the emission surface of the cathode 23 is a curve with a radius of curvature in the cutting plane, and the plane includes the propagation axis Z, which is not constant. Therefore, in the embodiment illustrated in Fig. 4d, the vertical radii φ of the emission surface is larger than the horizontal radii of the ratio. Therefore, the beam emitted by the cathode is more divergent in the horizontal direction than in the vertical direction. This embodiment does not constitute a limitation, and may be selected to be larger than Ry, because the astigmatism that must be compensated is introduced by the main focus lens and / or the magnetic deflection site is introduced. In the second embodiment of the present invention, as illustrated in Figs. 5a-5d, the field emission cathode 53 has an emission surface with a substantially upper plane. Each main emission area has an asymmetric structure so that the axis 26 of the emitted microbeam 20 and the propagation axis of the beam 32 output from the cathode 53 form an angle αη; the angle depends on the position of the microemitter 12 on the surface of the cathode. In terms of the maximum value around the cathode 53, it preferably increases linearly with the distance between the micro-emitter and the Z axis. Once the cathode is placed in the aperture of the first focusing electrode G3, the microbeam 20 seems to call itself, the same virtual image area 40 of "virtual cross" diverges, is located behind the cathode, and opposite to the focusing lens formed by the electrodes G3 and G4 electrodes As shown in Figs. 5c and 5d, the asymmetry of the beam direction in a predetermined direction can be achieved by shifting the asymmetry of the captured electric field or the collimated electric field into a space 54 of the transmitting element 12 and the collimating electrode 2 1 in the main emission area. The center of pore 5 5 this offset -11- 594825

⑺ It is preferable to increase linearly with the distance between the micro-emitter and the propagation axis z. It is also feasible to make the acquisition and alignment, coaxial with the aperture of the straight electrode and offset it from the emission point of the emission element 12. The beam astigmatism created by the cathode is generated by the rate of change of the offset 54, which _ varies with the position of the micro-emitter. Therefore, as illustrated in Fig. 5d, the degree of deviation of the micro-emitter 12 and the center of the aperture 55 located at an equal distance from the center of the cathode 53 depends on whether it is located on the vertical axis γ or the horizontal axis X. In the case of Figure 5d, the fact that the micro-emitter is offset by a value of 54x from the center of the cathode, which is smaller in the horizontal direction than the value 54y in the vertical direction, will make the beam more vertical in the horizontal direction than in the horizontal direction. For divergence. — The present invention has another advantage due to the fact that a cold-emitting micro-emitter can produce a cathode that is less sensitive to the emission current value of a hot cathode. This is because under the latter type of cathode, the emission area increases with the emission current, and the size of the beam also modifies the astigmatism of the beam, and the compromise between this astigmatism and the effect caused by the deflection field astigmatism. In the case of a cold-emitting emitter cathode, the emission surface does not change with the emission current, and the implementation of the present invention can avoid the need to use additional devices because it is complex and expensive to control the astigmatism of the beam based on the current. If only the astigmatism of the beam emitted by the micro-emitter is controlled, regardless of the length of the electron and grab, the implementation of the present invention can ensure that the area 40 is real. Therefore, the convergence point of the beam in the vertical and horizontal directions is located at the cathode and the main focus. Between the electrodes. This is equivalent to making the emission surface of the cathode in the case of the first embodiment a curve in a direction opposite to that illustrated in FIG. Similarly, in the case of the second embodiment, the offset 54 of the center of the cathode 54 may cause the microbeam to converge between the cathode and the focusing lens. The invention is not limited to the fabrication of a micro-emitter cathode having the above-mentioned microtip. Anti '-12- 594825

(8) Among other things, it can be used in a similar way and has the advantages of all aspects of field-effect microemitters, especially carbon-based planar microemitters. Whether the cathode of the present invention in all embodiments is applied to a single-beam single-tube electronic grabbing or a subscript color tube electronic grabbing or a three-beam electronic grabbing of a color tube. Description of symbols in the figure G1 First control electrode G2 Capture electrode G3 Focusing electrode G4 Electrode K Cathode D Total length 32 Full beam 2 Substrate 5 Cathode conductor 7 Resistor layer 8 Insulation layer 10 Extraction electrode 12 Microtip 20 Electronic microbeam 23 Circular cathode 26 Microbeam 40 Virtual image area 32 Beam 24 Insulation

-13- 594825 (9) 53 field emission cathode 54 offset 55 aperture 22 deceleration electrode

-14-

Claims (1)

594825 Patent Application No. 091136649 Chinese Application for Patent Scope Replacement (January 1993) Pick up and apply for Patent Scope 1, an electronic grab for a cathode ray tube, including: a first bias electrode, also known as a cathode conductor, At least one cold-emitting micro-emitter array, which is placed on the cathode conductor. The "Hei Secret emitter" is electrically connected to the cathode conductor and is used to emit an electron beam composed of several electron microbeams. Take an electrode, which is placed on the cathode conductor and penetrated by the pores on the micro-emitter, a-collimating electrode 'is used to reduce the emission angle of these micro-beams, the electron gun further comprises at least a focusing electrode, It is characterized in that the electronic grab includes a narrative device for converging the microbeams in the -area '. The way is that the electron beams composed of these microbeams converge in the vertical = horizontal direction. Two independent and substantial Looks like dots on the fields Ox and Oy. 2. For example, the electronic grab of the scope of patent application is characterized by the convergence device ^ The microbeams converge on the opposite side of the virtual image area electrode, which is located above the cathode. μ 3 · 4. 5. In the case of the patent application, the electron grab is achieved by the fact that the emitting part of the cathode is a curved surface and has a respective radius of curvature in the horizontal direction. : The electronic grab of item i in the scope of patent application, its feature = convergence. The convergence device includes a device for establishing a spatial asymmetry in the electric field in the microbeam regions. ° σ If the electronic grab of item 4 of the patent application scope is characterized by The application of the patent for the Fanyuan continuation page to establish the wrong place in the pen field ^,% device is achieved by a Yin i embedded k / or collimation electrode and the ancient seemingly upper electrode and / In the electrode plane of the micro-emitter, the fact that __A 4 1 _ is offset, and the rate of change of the offset value of the direction is another question, regardless of the fact that the change rate of the offset of the same plane σ is different. For example, the center of the electrode in the scope of patent application No. 5 is bismuth, and the characteristic is that the offset changes linearly with the distance from the ψ axis. It is characterized in that the cathode system is characterized in that the electron grabbing device, such as the first item in the patent application scope, is grabbed at the entrance of the first focusing electrode. A cathode ray tube including an electron grab is: a first bias electrode, also called a cathode conductor, at least one cold-emitting micro-emitter array, which is placed on the cathode conductor, and the micro-emitters are electrically connected To the cathode conductor, and used to emit an electron beam composed of several electron microbeams, an extraction electrode is placed on the cathode conductor and passed through a hole in the microemitter to collimate the electrode To reduce the emission angle of the microbeams, the electronic grab further includes at least one focusing electrode, which is characterized in that the electronic grab includes a receiving device for converging the microbeam to an area by means of The electron beam composed of the microbeams converges on two independent and substantially point-like regions 0χ and 0y in this region in the vertical and horizontal directions.