JPH06223722A - Spot size measuring device of cathode-ray tube - Google Patents

Abstract

PURPOSE:To measure the spot size with high accuracy and in a short time by interpolating the brightness distribution of the whole body from the brightness distributions of the spot before and after a minut change of the raster and the position, so as to infer the brightness distribution of the spot. CONSTITUTION:To the fluorescent screen 2 of a color cathode-ray tube 5 made in the operating condition by a driving device 6, a raster of a desired one color is made appear by the signal of a signal generator 7, and it is photographed by a camera 8 and stored in an image processing device 9. The device 9 obtains the brightness distribution corresponding to the luminous dots from the image signal Then, a spot with the color same as the raster is made appear by the generator 7, it is photographed by the camera 8, and a brightness distribution corresponding to plural emitter dots is obtained. It is corrected to regulate by a brightness distribution found from the raster. The position of the spot is converted minutely by the device 6, so as to obtain a brightness distribution in the same manner, they are slipped, superposed, and interpolated by making the converted distance as the standard, and the brightness distribution of a continuous spot is inferred so as to calculate the spot size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spot size measuring device for a color cathode ray tube having a phosphor screen composed of phosphor dots.

[0002]

2. Description of the Related Art Spot size measurement is one of the means for evaluating the resolution of a color cathode ray tube. As a method for measuring the spot size, Japanese Patent Laid-Open No. 62-243226 discloses a method in which a beam spot is made to appear in a predetermined area on the phosphor screen, and the brightness of the beam spot is measured through a video camera while the deflection current is being measured. Is disclosed, and the spot size is set to a value proportional to the difference between the deflection current when the luminance is maximum and the deflection current when the luminance is a predetermined ratio.

However, this measuring method has the following problems.

Generally, the brightness distribution of the beam spot is two-dimensionally distributed on the phosphor screen, and particularly in the peripheral part of the phosphor screen of the color cathode ray tube, the brightness distribution of the beam spot is asymmetric with respect to the center of the beam spot. Therefore, it is necessary to measure the luminance distribution of the entire beam spot and use the contour of the arbitrary cross section of the resulting two-dimensional luminance distribution as the spot size.

When such a two-dimensional luminance distribution is measured by the method of the above publication, it is necessary to measure the luminance by two-dimensionally and continuously deflecting the beam spot. Therefore, the measurement takes time. Further, if the relative displacement between the fluorescent surface of the color cathode ray tube and the video camera occurs during the luminance measurement, the accuracy of measuring the spot size may be significantly deteriorated, but it is possible to prevent the displacement. Have difficulty. In particular, in the measuring method of the above-mentioned publication, since it takes a long time to perform the measurement, there is a great possibility that a positional deviation will occur, and the measurement accuracy is likely to deteriorate.

[0006]

As described above, as a method of measuring the spot size of a color cathode ray tube, conventionally, a beam spot is made to appear on the phosphor screen and the deflection current is changed while measuring the brightness thereof. There is a method in which the spot size has a value proportional to the difference between the deflection current when the luminance is maximum and the deflection current when the luminance is a predetermined ratio.

However, in this method, the beam spot is set to 2
Since it is necessary to measure the luminance by dimensional and continuous deflection, it takes time to measure. Further, if the relative displacement between the fluorescent screen of the color cathode ray tube and the video camera occurs during the luminance measurement, the spot size measurement accuracy may be significantly deteriorated. For this reason, there is a problem that a positional deviation occurs and the measurement accuracy is likely to deteriorate.

The present invention has been made to solve the above problems, and an object of the present invention is to construct a spot size measuring device capable of measuring the spot size of a color cathode ray tube with high accuracy and in a short time.

[0009]

A driving device for driving a color cathode ray tube having a deflection yoke mounted thereon, and a signal for causing a raster and a spot to appear on a phosphor screen formed of phosphor dots of the color cathode ray tube. A signal generator, an imaging camera arranged to face the phosphor screen, an image processing device for processing an image signal sent from the imaging camera,
In a spot size measuring device of a color cathode ray tube having a driving device, a signal generator and a control device for controlling the image processing device, an image pickup camera for a raster appearing on a phosphor screen due to a signal from the signal generator in the image processing device. Means for processing the image signal sent from to detect the center coordinates of the plurality of phosphor dots in the raster and the brightness at the center coordinates, and to obtain the brightness distribution of the raster;
The image signal sent from the imaging camera is processed for the spot appearing on the phosphor screen by the signal from the signal generator to detect the brightness at each center coordinate of the plurality of light emitting phosphor dots in the spot, Means similar to the means for obtaining the luminance distribution, the means for correcting the luminance distribution of this spot by the luminance distribution of the raster, and the means for finely changing the position of the spot by driving the deflection yoke to obtain the luminance distribution of the spot. Then, the brightness distribution of the spot whose position is slightly changed is obtained, and means for normalizing and correcting this brightness distribution by means similar to the above-mentioned normalization correction and the normalized and corrected brightness distributions are superposed on the basis of the slightly changed distance. And a means for estimating the luminance distribution of the spot by interpolating the entire luminance distribution thus superposed.

[0010]

As described above, the image processing apparatus processes the image signal of the raster appearing on the phosphor screen to obtain the center coordinates of the plurality of phosphor dots in the raster and the brightness at the center coordinates. To detect the luminance distribution of the raster, and processing the image signal of the spot appearing on the phosphor screen to detect the luminance at each central coordinate of the plurality of light emitting phosphor dots in this spot, The same as the means for obtaining the luminance distribution of the spot, the means for normalizing and correcting the luminance distribution of the spot by the luminance distribution of the raster, and the means for finely changing the position of the spot by driving the deflection yoke to obtain the luminance distribution of the spot. Means for obtaining the luminance distribution of the spot whose position is slightly changed, and means for normalizing and correcting the luminance distribution by means similar to the means for normalizing and correcting the luminance distribution; If the means for estimating the brightness distribution of the spot by interpolating the overall brightness distribution thus overlapped with each other based on the slightly changed distance and changing the position of the spot In addition, since a plurality of light emitting phosphor dots are included in the spot, the number of changes of the brightness measurement position can be small and the measurement time can be shortened. Further, thereby, it is possible to prevent the measurement accuracy from deteriorating due to the relative displacement between the fluorescent screen and the image pickup camera, and it is possible to perform highly accurate measurement.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 1 shows a spot size measuring apparatus for a color cathode ray tube which is an embodiment of the present invention. This spot size measuring device emits blue, green and red light on the inner surface of panel 1.
A driving device 6 for driving a color cathode ray tube 5 in which a fluorescent screen 2 composed of color fluorescent dots is formed and a deflection yoke 4 is mounted outside the funnel 3, and a raster and spots are made to appear on the fluorescent screen 2. A signal generator 7 for selectively generating a video signal, an image pickup camera 8 arranged outside the panel 1 facing the fluorescent screen 2, and an image signal sent from the image pickup camera 8 is processed. Image processing device
9 and a control device 10 for controlling the drive device 6, the signal generator 7 and the image processing device 9. It should be noted that the image pickup camera 8 picks up an image of a raster or a spot through an optical lens having a magnification that allows each phosphor dot to be emitted to be individually identified when the raster or the spot appears on the phosphor screen 2.

The spot size is measured by the spot size measuring device as shown in FIG.

First, a deflection yoke 4 mounted on the outside of the color cathode ray tube 5 and its funnel 3 by a driving device 6
Fluorescent screen 2 of the color cathode ray tube 5 driven by the
On the top, the video signal generated from the signal generator 7
A color raster is made to appear, and the entire area of this raster is imaged by the imaging camera 8. In this case, any one that constitutes the phosphor screen 2
All the phosphor dots of color emit light, and as shown in FIG.
The brightness distribution on the phosphor screen 2 has a convex portion 12 corresponding to each phosphor dot 11. Note that arrow 13 represents relative brightness. At this time, the image captured by the light receiving portion of the image pickup camera 8 is of a size such that each light emitting phosphor dot 11 can be individually identified by the optical lens. The image signal sent from the imaging camera 8 corresponding to this image is
It is temporarily stored in the image memory of the image processing device 9.

The image processing device 9 fetches the above image signal from the image memory and, as shown in FIG. 4, sets the brightness distribution 14 on the phosphor dots 11 to a predetermined brightness value B0, for example, 1/2 of the maximum brightness. As the threshold value, the contour of the light emitting part in the cross section
Detect 16 Then, the center of gravity 16 of this light emitting portion is obtained, and this is set as the center coordinate 17 of the light emitting phosphor dot 11. Next, the brightness 18 at the center coordinates 17 is detected, and as shown in FIG. 5, a discrete brightness distribution corresponding to each light emitting phosphor dot 11 is obtained.
Get 19

Next, the phosphor screen 2 of the color cathode ray tube 5 is
A video signal generated from the signal generator 7 causes a spot of the same color as that when the raster appears to appear at a predetermined position above, and this spot is imaged by the imaging camera 8.
In this case, in the captured image, as shown in FIG. 6, a plurality of phosphor dots 11 in the spot 21 emit light and a plurality of convex portions 22 corresponding to the plurality of light emitting phosphor dots 11 are formed. The brightness distribution 23 has.

The image signal picked up by the image pickup camera 8 is sent to the image processing device 9 and, with respect to a plurality of light emitting phosphor dots 11 in the spot 21, at the center coordinates of the light emitting phosphor dots obtained for the raster. Detect the brightness of. Then, as shown in FIG. 7, a discrete luminance distribution 24 corresponding to each light emitting phosphor dot 11 is obtained. Further, the brightness distribution 24 is normalized and corrected by the discrete brightness distribution obtained from the raster.

Next, the deflection yoke 4 is driven by the driving device 6 to slightly change the position of the spot 21 at the predetermined position,
As shown in FIG. 8, the spot 21 with this position slightly changed
For a, as in the case of the spot at the above specified position,
The luminance distribution of a plurality of luminescent phosphor dots in the spot is measured to obtain a discrete luminance distribution 25 corresponding to each luminescent phosphor dot 11, and the luminance distribution 25 is obtained from the raster. To normalize and correct. As shown in FIG. 9, the luminance distribution is measured by slightly changing the position of this spot, and as shown in FIG. 9, at least the area 27 surrounded by four phosphor dots 11b to 11e close to one phosphor dot 11a is surrounded. It is repeated a plurality of times in the region 28 that satisfies 1/2, and the discrete luminance distribution obtained by each measurement is normalized by the discrete luminance distribution obtained from the raster.

Next, the luminance distributions obtained by the above-mentioned multiple measurements and normalized and corrected are overlapped with each other by shifting them with reference to the distance of the minute change to obtain a discrete luminance distribution 30 shown in FIG. Then, by interpolating the discrete brightness distribution 30 using a spline curve or the like, a brightness distribution 31 of the continuous spots 21 is estimated as shown in FIG.

Finally, with respect to the estimated luminance distribution 31, a luminance distribution on an arbitrary cross section, for example, a cross section taken along the line AA 'is obtained, and the spot size is calculated from this luminance distribution.

That is, as shown in FIG. 12, the width W at which the brightness value B2 of a predetermined ratio is calculated with respect to the maximum value B1 of the brightness distribution 32 on the arbitrary section is calculated, and this width W is spotted. Size.

Therefore, if the measurement is performed using the above-mentioned measuring device, it is not necessary to continuously change the position of the spot 21 minutely, and it is sufficient to measure the brightness at a plurality of positions, and the number of times the position of the spot 21 is minutely changed is reduced. Therefore, the measurement can be performed in a short time. Further, since the measurement can be performed in a short time, the possibility that the relative displacement between the phosphor screen 2 and the imaging camera 8 will occur is significantly reduced, and the measurement precision is not deteriorated due to the displacement. It is possible to measure.

Further, in the above measuring method, the brightness distribution at the center coordinates 17 of the light emitting phosphor dots 11 is obtained by making the raster appear, and the brightness distribution when the spot 21 is made to appear thereafter is normalized and corrected. This means that even when a uniform electron beam is incident on the phosphor screen 2, the luminance distribution of the light-emitting phosphor dots 11 varies depending on each phosphor dot 11, and is not constant. Since we are measuring the area including the body dot 11, eliminate the effect,
Highly accurate measurement can be performed.

It should be noted that in the above-mentioned embodiment, an arbitrary 1 is formed on the phosphor screen.
Although the case where the spot size is obtained by causing color rasters and spots to appear has been described, the present invention can also obtain the spot size in the same manner even when phosphor dots of a plurality of colors are emitted at the same time.

[0025]

A spot size measuring device for a color cathode ray tube is provided with a driving device for driving a color cathode ray tube having a deflection yoke mounted thereon, and a raster and spots are made to appear on a phosphor screen composed of phosphor dots of the color cathode ray tube. Generator for generating a signal for the purpose, an imaging camera arranged to face the phosphor screen, an image processing device for processing an image signal sent from the imaging camera, a drive device, a signal generator and image processing The image processing device comprises a control device for controlling the device, and the image processing device processes the image signal sent from the imaging camera for the raster appearing on the phosphor screen by the signal from the signal generator. Each of the center coordinates of the phosphor dots and the brightness at each center coordinate are detected, and the means for obtaining the brightness distribution of this raster and the signal from the signal generator are used. The image signal sent from the imaging camera is processed for the spot appearing at a predetermined position on the phosphor screen, the brightness at each center coordinate of the plurality of light emitting phosphor dots in this spot is detected, and the brightness distribution of this spot is calculated. A means for obtaining, a means for normalizing and correcting the brightness distribution of this spot by the brightness distribution of the raster, a position of the spot is slightly changed by the deflection yoke, and a position similar to the means for obtaining the brightness distribution of the spot is used to make this position small. Obtain the brightness distribution of the changed spots, and use the same means as the above-mentioned normalization correction to normalize and correct the brightness distribution, and the normalization-corrected brightness distributions are superposed on the basis of the distance of the minute change, and this superposition is performed. By providing a means for estimating the brightness distribution of the spot by interpolating the entire brightness distribution obtained, it is necessary to change the position of the spot by continuously deflecting. Since there is no, also includes a plurality of phosphor dots in the spot can be fewer number of changes of the luminance measuring position, to shorten the measurement time. Further, thereby, it is possible to prevent the measurement accuracy from deteriorating due to the relative displacement between the fluorescent screen and the image pickup camera, and it is possible to perform highly accurate measurement.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a spot size measuring apparatus for a color cathode ray tube according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a spot size measuring method by the measuring device.

FIG. 3 is a diagram showing a luminance distribution of a phosphor screen due to light emission of phosphor dots when a raster appears on the phosphor screen.

FIG. 4 is a diagram for explaining a center coordinate of a light emitting phosphor dot and a method of detecting luminance at the center coordinate.

FIG. 5 is a diagram showing a discrete brightness distribution of a phosphor screen obtained from detection of brightness at the center coordinates.

FIG. 6 is a diagram showing a luminance distribution due to luminescent phosphor dots in a spot when a spot appears on the phosphor screen.

FIG. 7 is a diagram showing a discrete luminance distribution at the central coordinates of the luminescent phosphor dots in the spot.

FIG. 8 is a diagram showing a discrete brightness distribution in the central coordinates of the light emitting phosphor dots when the position of the spot is slightly changed.

FIG. 9 is a diagram for explaining a measurement region when the spot position is slightly changed.

FIG. 10 is a diagram showing a discrete luminance distribution in the case where the discrete luminance distributions at the central coordinates of the light emitting phosphor dots when the position of the spot is slightly changed are normalized and overlapped.

FIG. 11 is a diagram showing a continuous spot brightness distribution obtained by interpolating the superimposed discrete brightness distributions.

FIG. 12 is a diagram for explaining a method of estimating a spot size from the continuous brightness distribution of spots.

[Explanation of symbols]

 2 ... Phosphor screen 4 ... Deflection yoke 5 ... Color cathode ray tube 6 ... Driving device 7 ... Signal generator 8 ... Imaging camera 9 ... Image processing device 10 ... Control device 11 ... Phosphor dots 14 ... Luminance distribution of phosphor dots 17 ... Center coordinates of phosphor dots 18 ... Luminance at center coordinates 19 ... Raster discrete brightness distribution 21 ... Spots 21a ... Spots with slightly changed position 23 ... Spot brightness distribution 24 ... Spot discrete brightness distribution 25 ... Position Discrete brightness distribution of spots with slight changes 30 ... Discrete brightness distribution of superposed spots 31 ... Continuous spot brightness distribution 32 ... Brightness distribution on arbitrary cross section

Claims (1)

[Claims] 1. A driving device for driving a color cathode ray tube having a deflection yoke mounted thereon, and a signal generator for generating a signal for causing a raster and a spot to appear on a phosphor screen formed of phosphor dots of the color cathode ray tube. An image pickup camera arranged to face the fluorescent screen, an image processing device for processing an image signal sent from the image pickup camera, and a control device for controlling the drive device, the signal generator and the image processing device. In the spot size measuring device for a color cathode ray tube having, the image processing device processes an image signal sent from the imaging camera for a raster appearing on the phosphor screen by a signal from the signal generator, A means for detecting the center coordinates of a plurality of phosphor dots in the raster and the brightness at the center coordinates, and obtaining the brightness distribution of the raster. An image signal sent from the imaging camera is processed for a spot appearing on the phosphor screen by a signal from the signal generator to detect the brightness at each center coordinate of a plurality of light emitting phosphor dots in the spot. , Means for obtaining the brightness distribution of this spot, means for normalizing and correcting the brightness distribution of this spot by the brightness distribution of the raster, and the position of the spot is minutely changed by driving the deflection yoke to obtain the brightness distribution of the spot. The luminance distribution of the spot whose position is slightly changed is obtained by a means similar to the means for obtaining, and the means for normalizing and correcting this luminance distribution by means similar to the above-mentioned normalizing correction, and the respective normalized and corrected luminance distributions. Means for estimating the luminance distribution of the spot by interpolating the entire luminance distribution thus superposed based on the distance of the minute change A spot size measuring device for a color cathode ray tube, comprising: