JP2679399B2 - Beam shape measuring device for color cathode ray tube - Google Patents

Description

The present invention relates to an apparatus for measuring the electron beam shape of a color cathode ray tube, and more particularly to an apparatus for measuring current density distribution.

[Conventional technology]

Conventionally, this type of color cathode ray tube beam shape measuring apparatus has used a raster scan method as means for projecting a beam spot on the color cathode ray tube. Further, in the shadow mask type cathode ray tube, the electron beam is partly blocked by the shadow mask as shown in FIG. 3, so that the measurement data is only measured in the conventional method measurement data of FIG. 28
You can get it like. With this, about half of the data is missing, and the true beam shape cannot be grasped. For this reason, the beam shape has been calculated by assuming that the current density distribution of the beam spot, and thus the luminance distribution, is a Gaussian distribution.

[Problems to be solved by the invention] The above-described conventional beam shape measuring apparatus hits the shadow mask before the electron beam reaches the screen,
As shown in FIG. 4, the entire beam cannot be projected on the screen. As a measure against this, approximate calculation is performed using a Gaussian distribution, but the shape of the beam does not fit on a Gaussian curve. For this reason, there is a drawback that true measurement can be performed only with a cathode ray tube without a shadow mask, such as a monochrome cathode ray tube.

Also, although the beam spot is projected, the beam scans the color CRT with the sawtooth wave deflection current, so the true beam spot cannot be projected, and the beam spot always has a certain width in the horizontal direction. Will end up.
Since the shape of this beam is measured, it cannot be called a true beam spot and causes a measurement error.

[Means for solving the problem]

According to the present invention, a means for projecting a monochromatic beam spot on the screen surface of the color cathode-ray tube to be measured by a DC deflection power source, and means for moving the beam spot at a constant pitch in the vertical and horizontal directions of the screen surface, There is provided a beam shape measuring device for a color cathode ray tube, which is provided with a means for imaging the beam spot, measuring the luminance, storing it in a memory, and outputting the beam shape.

〔Example〕

Next, the present invention will be described with reference to the drawings. First
The figure is a block diagram of one embodiment of the present invention. The color cathode-ray tube 1 to be measured has a deflection yoke 8 when measuring the beam spot.
Further, a DC horizontal power supply 17 and a DC vertical power supply 19 are connected by a deflection power supply switching device 21 and DC is deflected. Further, a voltage is applied to each electrode of the color CRT 1 by the signal generator 7 and the CRT tester 6 so that only one point on the screen surface emits a single color. On the other hand, the CCD camera 2 fixed to the color cathode-ray tube 1 fixes the beam spot projected on the screen through the lens unit 3 and magnifies the beam spot 100 times, for example. The detected data is, for example, 50 columns in the horizontal direction,
It is acquired as a matrix of 20 rows in the vertical direction, and the sum within the data acquisition area in the preset matrix is calculated. This is to reduce noise, so CCD camera 2
The data of a plurality of pixels is referred to instead of the data of only one pixel. However, if the data acquisition area is not sufficiently smaller than 1/10 of the diameter of the beam spot, it will cause an error. For example, the diameter of the beam spot is 0.
At 6 mm, the capture area must be less than 60 μm. In FIG. 4, the data capture area 31 of FIG. 5 is set for the beam spot 29, which is smaller than the emission dot 30.

Next, in FIG. 1, the DC horizontal power supply 17 is increased by a predetermined number of steps, for example, 1 mA, and the measurement is performed again. When the measurement in the horizontal direction is completed a predetermined number of times, for example 50 times, the DC vertical power supply 19 is increased by a predetermined number of steps, for example, 0.1 mA, the measurement is performed again, and the brightness data is stored in the image memory 14. Repeating this, the beam spot is moved and measured, for example, in the horizontal direction 50
The luminance data of 2500 points can be obtained by measuring the number of times and 50 times in the vertical direction.

This is shown in FIG. 2, which is a shadow mask.
The imaging system 24 is installed in a portion not shielded by 23, and the beam spot 22 is sequentially moved at a predetermined pitch like 22a to 22m, so that the brightness increases as the beam spot approaches the imaging system 24, The brightness gradually decreases as it goes away from the center. As a result, this method measurement data 25
Is obtained, and a three-dimensional data curve is obtained by performing this in both horizontal and vertical directions. When the measurement of one cathode, for example, the red cathode is completed, the measurement of the green and blue cathodes is then performed in the same manner.

〔The invention's effect〕

As described above, according to the present invention, since the beam spot is not scanned, the true beam spot can be projected on the screen of the color cathode ray tube and can be measured. In addition to a color CRT without a shadow mask, even when a shadow mask is provided and a part of the beam spot is shielded, the true beam shape that does not include an error due to the approximate curve can be accurately measured.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram illustrating a measuring method according to the present invention, FIG. 3 is a diagram illustrating a conventional measuring method, and FIG. 4 is a phosphor and a beam spot. Fig. 5 is a diagram showing the diameter of Fig. 5, and Fig. 5 is a diagram showing the phosphor and the measurement region. 1 ... Color cathode ray tube to be measured, 2 ... CCD camera, 3
…… Lens section, 4 …… Camera monitor, 5 …… Computer,
6 ... CRT tester, 7 ... signal generator, 8 ... deflection yoke, 9 ... output monitor, 10 ... XY stage, 11 ...
X-axis motor, 12 …… Y-axis motor, 13 …… Pulse motor controller, 14 …… Image memory, 15 …… Communication controller, 16 …… IO controller, 17 …… DC horizontal power supply, 18 …… Horizontal deflection power supply, 19 ... DC vertical power supply, 20 ... vertical deflection power supply, 21 ... deflection power supply switching device, 22 ...
… Beam spot, 23 …… Shadow mask, 24 …… Imaging system, 25 …… Measuring data of this method, 26 …… Beam spot,
27 …… Imaging system, 28 …… Conventional method measurement data, 29 …… Beam spot, 30 …… Emitting dot, 31 …… Data acquisition area, 32 …… Non-emitting dot.

Claims (1)

(57) [Claims] 1. A means for projecting a monochromatic beam spot on a screen surface of a color cathode ray tube to be measured by a direct current deflection power source, and a means for moving the beam spot at a constant pitch in the vertical and horizontal directions of the screen surface. Means for imaging the beam spot, measuring the brightness, storing it in a memory and outputting the beam shape, the means for moving the beam spot changing the DC deflection power supply by a predetermined number of steps, A beam shape measuring device for a color cathode ray tube, wherein the beam spot is sequentially moved at a predetermined pitch by means of.