JPH09259766A - Measuring device and measuring method of electron beam - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the beam spot size on a phosphor screen of an in-line three-beam system cathode-ray tube. SOLUTION: An electron beam 2 generated by an electron gun reaches a phosphor screen 4 by passing through an aperture grille 3, and emits the light from a phosphor. In measurement of a beam spot of the electron beam 2 reaching a surface of this phosphor screen 4, it is taken in by an image pickup device 5 such as a CCD camera, and picture processing is performed by a computer 6, and a spot shape is evaluated, and an electric current flowing to electromagnetic coils 7a and 7b is found on the basis of its evaluation, and the electric current is flowed by controlling a DC power source (g). A magnetic field B is generated according to this flowed electric current, and force F acts on the electron beam by the action of this and electric charge of a flying electron beam, and a flying orbit of the electron beam is changed. The direction of the magnetic field B and the force F is reversed by the direction of the electric current, and the flying orbit of the electron beam can be controlled even in either direction in a horizontal plane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam measuring apparatus and measuring method, and more particularly to measuring by moving a beam spot on a phosphor screen of an in-line three-beam type color cathode ray tube to a position suitable for measurement. The present invention relates to an electron beam measuring apparatus and measuring method.

[0002]

2. Description of the Related Art The measurement of the beam spot size of a conventional in-line three-beam type color cathode ray tube (hereinafter simply referred to as "cathode ray tube") will be described with reference to FIGS. FIG. 4 is a cross-sectional view showing the structure of the cathode ray tube as seen from above, and FIG. 5 is a schematic configuration diagram of a beam spot size measuring system of this cathode ray tube. 6 to 8 are diagrams showing the beam spot position and the luminance distribution on the phosphor screen.

FIG. 4 shows an in-line three-beam type color cathode ray tube in which R, G, and B are arranged in-line with red, green, and blue electron beams, respectively, and a plane including the three electron beams is a horizontal plane ( Match the page). Red, green, and blue phosphor stripes (reference numeral 20 in FIG. 6) are repeatedly formed on the phosphor screen 4 on the inner surface of the panel 13, and the array direction is the horizontal direction and the extending direction is the vertical direction ( The direction perpendicular to the paper surface). Further, reference numeral 3 is an aperture grill arranged so as to face the phosphor screen 4, and is composed of a number of metal wires stretched in parallel on the frame 14, and the arrangement direction is horizontal and The present direction is the vertical direction. An electron gun 1 provided with three cathodes, five grid electrodes and a focusing electrode is provided inside the neck 10, and R, G emitted from the electron gun 1 are provided.
The beam of B is deflected by the deflection coil 11, passes through the aperture grill 3 and reaches the phosphor screen 4.

Conventionally, as shown in FIG. 5, the measurement of the beam spot of the electron beam 2 arriving on the phosphor screen 4 is captured by an image pickup device 5 such as a CCD camera, image-processed by a computer 6, and spotted. The shape has been evaluated, and the electron gun 1 and the like have been adjusted based on the evaluation.

The position and brightness distribution of the beam spot 15 of the electron beam 2 that has reached the phosphor screen 4 and the evaluation of the beam spot shape based on this will be described with reference to FIGS. The green (G) beam is described here, and the red (R) and blue (B) phosphor stripes 20 do not emit light.
Further, it is natural that the red (R) and blue (B) beams are described in the same manner as the green (G) beam.

First, as shown in FIG. 6A, when the green beam spot 15 hits the green phosphor stripe 20 on the phosphor screen 4, light is emitted, and red (R) and blue ( The place where it hits the phosphor stripe 20 and the carbon stripe 21 in B) remains dark. Therefore, the end portion in the horizontal direction (X axis) does not emit light and is hidden and invisible. Such a beam spot 15
When the image pickup device 5 takes in, the data of the luminance distribution is as shown in FIG. In this case, since there is no data at the end in the horizontal direction, the shape of the beam spot 15 is estimated from the approximated curve, and there is a problem that the accuracy of the value becomes low.

Further, FIG. 7 shows a case where only the right end portion of the beam spot 15 and FIG. 8 shows a case where only the left end portion of the beam spot 15 hits the phosphor stripe 20 and emits light correctly. Therefore, in this case, a highly accurate approximate curve of the brightness distribution in the vicinity thereof can be obtained. However, the position where the beam spot 15 reaches the phosphor screen 4 is not constant, and in many cases, both ends in the horizontal direction are hidden as shown in FIG. This is because the assembly accuracy of the electron gun 1 and the mounting accuracy of the electron gun 1 to the neck 10 have variations.

[0008]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to displace the beam trajectory of an in-line three-beam type color cathode ray tube in the horizontal direction by a simple device which can be controlled by a computer, and to make a beam spot on a phosphor screen. It is an object of the present invention to provide an apparatus and a method capable of correcting the position of the spot and accurately measuring the spot size.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is a main part of an electron gun in a measuring apparatus for measuring a beam spot on a phosphor screen of an in-line three-beam type color cathode ray tube. Take a picture of the beam spot on the phosphor screen, a pair of electromagnetic coils up and down across the neck of the color cathode ray tube at a predetermined position in the direction of the phosphor screen from the center of the lens, a power supply that applies current to the electromagnetic coils. And an image pickup apparatus for analyzing the image captured by the image pickup apparatus, and a control means for controlling the power supply according to the result of the image pickup apparatus.

The electron beam measuring device is used to change the polarity from the power source to the electromagnetic coil to pass a current, and the trajectory of the beam spot is controlled by the magnetic field generated by the current, so that the beam on the phosphor screen is controlled. The above problem is solved by using an electron beam measuring method in which the position of the spot is moved to a position most suitable for the measurement and the measurement is performed.

Therefore, by using the electron beam measuring apparatus and measuring method according to the present invention, the voltage of the electromagnetic coil arranged at the neck of the cathode ray tube is controlled by the computer to move the beam spot on the phosphor screen to the optimum position. By doing so, a more accurate spot size can be measured.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electron beam measuring apparatus and measuring method according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a beam spot size measuring system for a cathode ray tube according to the present invention, FIG. 2 is a diagram showing a positional relationship between an electron gun and an electromagnetic coil in this measuring system, and FIG. 3 is a diagram showing an electromagnetic coil. It is a figure for demonstrating the interaction of a magnetic field and an electron beam.

First, as shown in FIG. 1, the electron beam 2 measuring apparatus according to the present invention supplies a DC power source 8 controlled by a computer 6 to the conventional measuring apparatus shown in FIG. 5, and a current is supplied from this DC power source 8. The electromagnetic coils 7a and 7b are added. The electromagnetic coils 7a, 7b generate a force F on the electron beam 2 flying by the magnetic field B generated by the electromagnetic coils 7a, 7b.
It is provided to control the flight trajectory of the aircraft.

An electron beam 2 generated by an electron gun (not shown) passes through an aperture grill 3 and reaches a phosphor screen 4 to cause the phosphor to emit light. The measurement of the beam spot of the electron beam 2 that has reached the phosphor screen 4 is captured by an image pickup device 5 such as a CCD camera, image processed by a computer 6, the spot shape is evaluated, and the electromagnetic coil is based on the evaluation. Find the currents that flow in 7a and 7b,
The direct current power supply 8 is controlled to flow a current. A magnetic field B is generated in accordance with the flowed current, and a force F acts on the electron beam due to the action of the magnetic field B and the charges of the flying electron beam to change the flight trajectory of the electron beam. The directions of the magnetic field B and the force F are reversed depending on the direction of the electric current, so that the flight trajectory of the electron beam can be controlled in any direction in the horizontal plane.

Next, the setting positions of the above-mentioned electromagnetic coils 7a and 7b will be described with reference to FIG. FIG. 2 is an enlarged view of the neck portion 10 of the cathode ray tube shown in FIG. The electron gun 1 includes a red cathode KR, a green cathode KG, a blue cathode KB, and grit electrodes G1, G2, G3, G4, G.
5 and the focusing electrode CP, and the electromagnetic coils 7a, 7
b is a predetermined position in the direction of the phosphor screen 4 from the center of the main lens composed of the grit electrodes G3, G4, G5, and is set up and down with the neck 10 near the center of the grit electrode G5 (broken line part) sandwiched. It

Trajectory control of the electron beam 2 by the measuring apparatus of the present invention will be described in detail with reference to FIG.

First, FIG. 3A shows a pair of electromagnetic coils 7.
This is a case where a current is applied so that the upper side of a and 7b becomes the N pole and the lower side becomes the S pole, and the magnetic field B directed from the upper side to the lower side is given to the electron beam 2. In this case, a force F is applied to the electron beam 2 in the leftward horizontal direction due to the interaction with the magnetic field B, and the electron beam 2 is displaced leftward. As a result, the beam spot 15 on the phosphor screen 4 can be moved from the state in which the horizontal end shown in FIG. 6A cannot be seen to the state in which the right end can be seen as shown in FIG. 7A. Therefore, the position of the right end of the beam spot 15 can be accurately imaged by the imaging device 5. This beam spot 15
6B. In this case, since the approximation accuracy on the right side is high in this case, the size of the right half of the beam spot 15 is from the position of the peak of the brightness distribution to the distance at the right end.

Next, FIG. 3B shows a pair of electromagnetic coils 7
This is a case where a current is applied so that the upper side of a and 7b becomes the S pole and the lower side becomes the N pole, and the magnetic field B directed from the bottom to the top is given to the electron beam 2. In this case, a force F is applied to the electron beam 2 in the rightward horizontal direction due to the interaction with the magnetic field B, and the electron beam 2 is displaced rightward. As a result, the beam spot 15 on the phosphor screen 4 can be moved from the state in which the horizontal end shown in FIG. 6A cannot be seen to the state in which the left end can be seen as shown in FIG. 8A. Therefore, the position of the left end of the beam spot 15 can be accurately photographed by the imaging device 5. This beam spot 15
7B. In this case, since the approximation accuracy on the left side is high in this case, the size of the left half of the beam spot 15 is set from the position of the peak of the brightness distribution to the distance to the left end.

As described above, the size of the horizontal beam spot 15 can be accurately measured by adding the two measurement results. Green here (G)
Although the description has been made by focusing on the electron beam of No. 2, it is natural that the same applies to the red (R) or blue (B) beam.

[0020]

According to the measuring device and the measuring method of the present invention, the horizontal size of the beam spot on the phosphor screen can be measured with higher accuracy in the inline three-beam type color cathode ray tube. , In addition,
Horizontal static convergence can also be measured with high accuracy.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a beam spot size measuring system of an in-line three-beam type color cathode ray tube according to the present invention.

FIG. 2 is a diagram showing a positional relationship between an electron gun and an electromagnetic coil in the measurement system of the present invention.

FIG. 3 is a diagram for explaining the interaction between a magnetic field and an electron beam by an electromagnetic coil.

FIG. 4 is a cross-sectional view showing the structure of an in-line three-beam type color cathode ray tube.

FIG. 5 is a schematic configuration diagram of a beam spot size measuring system of a conventional in-line three-beam type color cathode ray tube.

FIG. 6 is a diagram showing a beam spot position and a luminance distribution on a phosphor screen.

FIG. 7 is a diagram showing a beam spot position and a luminance distribution on a phosphor screen.

FIG. 8 is a diagram showing a beam spot position and a luminance distribution on a phosphor screen.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron gun, 2 ... Electron beam, 3 ... Aperture grill, 4 ... Phosphor screen 5 ... Imaging device, 6 ... Computer, 7a, 7b ... Electromagnetic coil, 8 ... DC power supply 10 ... Neck, 11 ... Deflection coil, 12 … Funnel,
13 ... Panel 14 ... Frame, 15 ... Beam spot, 20 ... Phosphor stripe 21 ... Carbon stripe

Claims (2)

[Claims] 1. A measuring device for measuring a beam spot on a phosphor screen of an in-line three-beam type color cathode ray tube, wherein the color cathode ray tube is placed at a predetermined position in the phosphor screen direction from the center of the main lens of the electron gun. A pair of electromagnetic coils above and below the neck, a power supply for applying a current to the electromagnetic coils, an imaging device for imaging the beam spot on the phosphor screen, and an image captured by the imaging device. And a control means for controlling the power source. 2. The polarity of the power source is switched to the electromagnetic coil to flow an electric current, and the trajectory of the beam spot is controlled by a magnetic field generated by the electric current, so that the position of the beam spot on the phosphor screen is optimal for measurement. The electron beam measurement method using the electron beam measurement apparatus according to claim 1, wherein the measurement is performed by moving to another position.