JP2000146753A - Method and apparatus for evaluating uniformity of cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure objectivity and reliability of uniformity evaluation results by performing quantitative and multi-dimensional evaluation. SOLUTION: Display screen of a cathode ray tube to be evaluated is read out optically (S20), a chromaticity data at a specified part on the display screen is obtained from the read out results (S30, S40), an evaluation result values are calculated for a plurality of predetermined evaluation terms based on the chromaticity data (S50), the calculated evaluation result values are expressed in terms of evaluation result rank values according to a preset conversion table (S60), and uniformity evaluation values for the display screen of the cathode ray tube are calculated from the rank values obtained for the plurality of evaluation terms (S70).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube uniformity evaluation method and apparatus for evaluating spatial uniformity of chromaticity and luminance of a screen in a color cathode ray tube, so-called uniformity.

[0002]

2. Description of the Related Art Generally, in a color cathode ray tube, uniformity (hereinafter abbreviated as "UF") is one of important characteristics. In particular, white screen uniformity, so-called white uniformity (hereinafter, “W-UF”)
Is abbreviated).

[0003] Conventionally, W-UF evaluation of a color cathode ray tube is performed by an operator or a judge (evaluator) who performs an evaluation while a white screen is displayed on the color cathode ray tube to be evaluated. By doing so.

[0004]

However, in the above-mentioned conventional W-UF evaluation method, there is, of course, a disadvantage that the portion depending on the evaluator is large and the reliability of the evaluation is reduced. On the other hand, if the evaluation is performed by a plurality of persons, the reliability can be improved, but it is not practically appropriate to manage the evaluation process and the like. Further, the evaluation depending on the sensory of the evaluator is not suitable for grasping the transition of the UF over a long period of time.

In order to alleviate such a problem, it is effective to quantitatively evaluate W-UF. As a quantitative W-UF evaluation method, for example, in a state where a white screen is displayed on a color cathode ray tube to be evaluated, chromaticity is measured at a plurality of positions on the screen, and a color difference between each is measured. It is conceivable to obtain the W-UF evaluation result by obtaining it.

However, in the evaluation of W-UF by the evaluation method based only on the color difference, it is not possible to obtain a necessary and sufficient evaluation result according to the actual situation. This is about UF
Because it is not possible to deny the importance of the sensuality of the viewer of the screen of the cathode ray tube, it is not merely a one-dimensional evaluation based solely on color difference, but, for example, differences in sensitivity of colors displayed on the screen and degree / area of the color. This is because an evaluation based on a multidimensional (multidimensional) index is required.

Accordingly, the present invention has been made in view of these problems, and enables a quantitative and multi-dimensional evaluation, thereby ensuring the objectivity and reliability of the evaluation result. It is an object to provide an evaluation method and an evaluation device.

[0008]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for evaluating a uniformity representing color uniformity on a screen displayed by a cathode ray tube by a method devised to achieve the above object. An evaluation method, wherein a display screen of a cathode ray tube to be evaluated is optically read, chromaticity data at a predetermined location on the display screen is obtained from the read result, and the chromaticity data is defined in advance based on the chromaticity data. The evaluation result values for the plurality of evaluation items are calculated, and the calculated evaluation result values are converted into the rank values of the evaluation results according to a preset conversion table, and the ranks for the plurality of evaluation items obtained by the conversion are calculated. A uniformity evaluation value for the display screen of the cathode ray tube is calculated from the value.

Further, the present invention has been devised to achieve the above object, and is a uniformity evaluation apparatus for a cathode ray tube for evaluating uniformity representing color uniformity on a screen displayed by a cathode ray tube. Reading means for optically reading a display screen of a cathode ray tube to be evaluated; chromaticity data obtaining means for obtaining chromaticity data at a predetermined location on the display screen from a result of reading by the reading means; An evaluation result calculating unit that calculates an evaluation result value for a plurality of evaluation items defined in advance based on the chromaticity data obtained by the data obtaining unit; and an evaluation result value calculated by the evaluation result calculating unit. A rank value conversion means for converting into a rank value of the evaluation result in accordance with the conversion table, and a rank value for the plurality of evaluation items converted by the rank value conversion means. It is obtained by anda uniformity calculating means for calculating the uniformity evaluation value with respect to the display screen of the cathode ray tube.

According to the uniformity evaluation method according to the above-described procedure and the uniformity evaluation device having the above-described configuration, when evaluating the uniformity of the cathode ray tube to be evaluated, the uniformity is obtained from a predetermined position on the display screen of the cathode ray tube. Based on the chromaticity data, calculate the evaluation result values for a plurality of evaluation items, convert the evaluation result values of each item into the rank values of the evaluation results, and calculate the uniformity evaluation value from these rank values. It has become. Therefore, if the uniformity of the cathode ray tube is evaluated using this evaluation method or evaluation apparatus, multidimensional evaluation can be performed through the evaluation result values for a plurality of evaluation items, and the evaluation result values have passed. Since the uniformity evaluation value is calculated later, a quantitative uniformity evaluation result can be obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method and an apparatus for evaluating uniformity of a cathode ray tube according to the present invention will be described below with reference to the drawings. However, here, the case where the present invention is applied to the evaluation of W-UF for a color cathode ray tube will be described as an example.

FIG. 1 is a flowchart showing an example of an evaluation method according to the present invention, and FIG. 2 is a block diagram showing an example of an evaluation device according to the present invention.

[Explanation of Schematic Configuration] First, a system configuration necessary for implementing the evaluation method according to the present invention, that is, a system configuration of the evaluation apparatus according to the present invention will be described with reference to FIG.

This uniformity evaluation device is a CC
It comprises a D (Charge Coupled Device) camera 1 and a computer device 2.

The CCD camera 1 is for optically reading the display screen of the color cathode ray tube 3 to be evaluated. However, the CCD camera 1 can read a color image and can output data as a reading result to the computer device 2.

On the other hand, the computer device 2 comprises, for example, a personal computer and has a function of performing predetermined information processing (arithmetic processing), which will be described in detail later. Specifically, for example, it is conceivable to realize such a function by installing “Excel” which is spreadsheet software of Microsoft Corporation in the United States.

The CCD camera 1 and the computer device 2 are configured so that output data from the CCD camera 1 can be transmitted / received via a communication line connecting them or a storage medium such as a magneto-optical disk. Shall be

Next, the procedure of the W-UF evaluation performed by the evaluation apparatus having the above system configuration, that is, the evaluation method in the present embodiment will be described with reference to FIG.

[Acquisition of Chromaticity Data] As shown in FIG. 1A, when evaluating the W-UF of the color cathode ray tube 3, first, a white screen is displayed on the color cathode ray tube 3 to be evaluated. (Step 10, hereinafter step is abbreviated as S),
The display screen is read by the CCD camera 1 (S20).
Then, the reading result is output from the CCD camera 1 to the computer device 2.

However, at this time, the CCD camera 1 outputs to the computer device 2 only the reading result of a predetermined portion on the display screen. Specifically, as shown in FIG. 3, a read result is output for 441 locations defined as a mesh of 21 locations in the horizontal direction × 21 locations in the vertical direction on the display screen. This secures data necessary for highly accurate evaluation of the entire display screen of the color cathode ray tube 3,
This is to reduce the data transfer load between the CCD camera 1 and the computer device 2.

As a result, the computer device 2 is
As shown in (a), for each of 21 × 21 locations on the display screen, the intensity of the color stimulus is normalized based on the xy chromaticity diagram specified by the CIE (International Commission on Illumination) to obtain xy.
Chromaticity data represented by coordinates (hereinafter, this chromaticity data is referred to as “Y
xy (i, j) "(where i = 1 to 21, j = 1 to 2)
1) is acquired (S30). Note that CC
The acquisition (conversion) of Yxy (i, j) from the reading result of the D camera 1 may be performed by the CCD camera 1 side or the computer apparatus 2 side. In addition, since the conversion process itself uses a well-known technique, a detailed description is omitted here.

Yxy for 21 × 21 locations on the display screen
After obtaining (i, j), the computer device 2
Is to adjust its Y
xy (i, j) is represented by Yu'v '(i, j) which is a chromaticity data value on a chromaticity diagram specified by CIE1976 UCS.
(S40). This conversion is performed according to the so-called Eastwood method (1),
The calculation may be performed using the equation (2).

[0023]

(Equation 1)

[0024]

(Equation 2)

Using the equations (1) and (2), Yu'v '
After obtaining (i, j), the computer device 2 then quantifies the UF parameters, which are a plurality of predefined evaluation items, based on these, that is, calculates the evaluation result value for each UF parameter. Is performed (S50). The UF parameters for which the computer device 2 performs quantification include, for example, color intensity (D), color width (SJ),
Color contrast (P), contrast enhancement (PD), and other items (CV, E). Here, these UF
The quantification of parameters will be described in detail.

[Calculation of Color Intensity (D)] As shown in FIG. 1B, the computer device 2 calculates the color intensity (D) as one of the quantifications of the UF parameter ( S5
1).

The color intensity is an evaluation item for the color spread on the display screen, that is, an evaluation item for the maximum value of the shift amount from the reference white position on the CIE xy chromaticity diagram. Specifically, as shown in FIG.
When each of 21 Yu'v '(i, j) is plotted on the coordinate axis, it corresponds to the size of the diagonal of a rectangle formed by the maximum plot point and the minimum plot point for each axis. .

The computer apparatus 2 quantifies such color strength according to the following procedure. First, a point at the lower left of the 21 × 21 locations on the display screen is taken as a base point. Then, the direction of the x-axis / y-axis is matched with that of the display screen of the cathode ray tube 3. This gives u ′ and v ′
Is, as shown in the following equations (3) and (4), x
And y are plane functions.

[0029]

(Equation 3)

[0030]

(Equation 4)

Further, assuming that the x-direction interval of each of 21 × 21 points on the display screen is m and the y-direction interval is n, Yu′v ′ at the i-th point in the x-direction and the j-th point in the y-direction is obtained. The values u'ij and v'ij are obtained by the following equations (5) and (6).

[0032]

(Equation 5)

[0033]

(Equation 6)

Based on these equations, the computer apparatus 2 calculates the color intensity (D) by the following equation (7).

[0035]

(Equation 7)

In this example, the length of a diagonal line of a square having two vertices at which x and y are independently furthest apart from each other on the display screen is represented by a Jend (Jnd) display by the Eastwood method. Therefore, the value of D increases as the color intensity increases. When the unevenness on the u′v ′ plane is expressed, the height of the unevenness corresponds to the value of D.

[Calculation of Color Size (SJ)] After quantifying the color intensity (D), the computer device 2 then sets the color size (SJ) as shown in FIG. Sa (SJ)
Is calculated (S52).

The color area is an evaluation item for the area of a colored area on the display screen, that is, an evaluation item for how many areas have a large color intensity value. Specifically, each 21 × 21 Yu′v ′ (i, i,
When j) is plotted on a coordinate axis, it corresponds to the sum of the distances between each plot point and a predetermined origin.
However, the origin at this time is not the center of the screen but the average chromaticity point.

The computer apparatus 2 quantifies such a color range in the following procedure. First, 21
For each of the 21 Yu'v '(i, j), the deviation from the origin in Jnd is calculated using the following equation (8).

[0040]

(Equation 8)

Then, taking the area of the degree of color into consideration, the sum (SJ) of the sum of the results of the Jnd display at each location is calculated by the following equation (9). Of the evaluation result.

[0042]

(Equation 9)

Since this is added for each of the 441 points, the value varies depending on the size and area of the Jnd display itself, and as a result, the value takes into account the area of the color intensity (degree).

[Calculation of Color Contrast (P)] Next, the computer 2 calculates a color contrast (P) as one of the quantifications of the UF parameters (S53).

The color contrast is an evaluation item for the amount of color change at each adjacent portion on the display screen, and specifically, is a u ′ (x, y) plane or a v ′ (x, y) plane. Are evaluation items related to the flatness of the color intensity in the above.

In general, the u '(x, y) plane or v'
There are several methods for defining the flatness of the color intensity in the (x, y) plane, but here, for convenience of calculation, FIG.
As shown in the figure, the point (i,
The angle ψ between the normal vector of the tangent plane in j) and the u ′ axis
u′ij, the angle ψu′ij between the v ′ axis and the normal vector of the tangent plane at the point (i, j) in the v ′ (x, y) plane
Is the amount (P) representing the color contrast.

The computer apparatus 2 quantifies such a color comparison according to the following procedure. u '= u'
Since the total derivative of (x, y) is expressed by the following equation (10), the equation of the tangent plane at the point (i, j) on the u ′ (x, y) plane is expressed by the following equation (11). And the equation of the normal vector is given by the following equation (12).

[0048]

(Equation 10)

[0049]

[Equation 11]

[0050]

(Equation 12)

The partial differential coefficients of u 'in the x and y directions are expressed by the following equations (13) and (14) since u' is a discrete function of x and y.

[0052]

(Equation 13)

[0053]

[Equation 14]

Therefore, the angle ψu′ij between the normal vector of the tangent plane at the point (i, j) on the u ′ (x, y) plane and the u ′ axis is expressed by the following equation (15). Become.

[0055]

(Equation 15)

Equation (13) and (1) are added to equation (15).
By substituting the partial derivative according to equation 4), the angle ψu'ij at each location can be obtained. The same applies to the angle ψv'ij in the v '(x, y) plane.

Based on these, the computer device 2
Calculates the color contrast (P) by the following equation (16).

[0058]

(Equation 16)

This is the sum of the angle ψu'ij and the angle ψu'ij at each of 21 × 21 points. Therefore, the value of the color contrast (P) changes depending on the degree of the contrast and the area thereof, and becomes closer to “0” as the flatness is improved without the color contrast.

[Calculation of Contrast Enhancement (PD)] After the quantification of the color contrast (P), the computer device 2 then performs the enhancement of the contrast (P) as shown in FIG.
D) is calculated (S54).

The emphasis of the contrast is obtained by differentiating the amount of color change near the reference white color from the amount of color change near the other colors in the color comparison (P) described above. That is, it is an evaluation item that emphasizes comparison of colors other than around the reference white.

Specifically, the computer device 2 adjusts the chromaticity deviation (（) at the angle of the normal vector of the tangent plane at the point (i, j) in order to emphasize the color contrast (P). Δ
u ′) is multiplied by u ′ and v ′ to obtain a sum of squares. That is, the computer device 2 emphasizes the contrast (P
D) is calculated by the following equation (17).

[0063]

[Equation 17]

As a result, when the contrast in a strong color portion is large, the value of the contrast enhancement (PD) also increases accordingly.

[Calculation of Other Items (CV, E)] Next, the computer device 2 calculates other evaluation items as one of the quantifications of the UF parameters (S5).
5). The other evaluation items here include, for example, a color unevenness rate (CV) and a ΔEa ^* b ^* value (E).

The color unevenness rate (CV) is defined as Yxy (i, j)
Color unevenness rate (%) corresponding to white screen calculated based on
For example, it is measured by a surface unevenness measuring device using a general method. The surface unevenness measuring device is for measuring the brightness, saturation, and hue of a surface (a plurality of points) to comprehensively evaluate the color on the surface.

On the other hand, the ΔEa ^* b ^* value (E) is defined as Yxy
(I, j) is converted to an L ^* a ^* b ^* color system defined by the CIE, and corresponds to a color difference in a color space calculated using a general method based on this. . In addition,
The ΔEa ^* b ^* value (E) is an average value of the color difference between each part on the display screen.

[Conversion to UF Rank] When the quantification of each UF parameter is performed as described above, the computer device 2 then proceeds to the respective UF parameters as shown in FIG.
The evaluation result values for parameter
The value is converted into a value representing the degree of UF evaluation (hereinafter, referred to as “UF rank”) (S60).

At this time, it is assumed that the computer device 2 previously stores, for example, a conversion table as shown in FIG. 6 for conversion into the UF rank. Then, in the computer device 2, according to this conversion table, each UF
The evaluation result values for the parameters 1 to are individually converted into UF ranks.

According to this conversion table, the UF rank is specified according to which range (between the black circles in the figure) the evaluation result value of the UF parameter belongs to. For example, the UF rank for the color intensity (D) is Rk
(D), the evaluation result value of the color intensity (D) is “2.
20 ”, the value of the UF rank Rk (D) is“ 4.0 ”.
0 ". The conversion table is empirically determined based on an experimental result that specifies the correspondence between the evaluation result value for each UF parameter and the result of the sensory evaluation visually observed by the evaluator.

The reason why the evaluation result value of the UF parameter is converted into the UF rank and the conversion is individually performed for each of the UF parameters is as follows. That is, as is clear from the conversion table, the distribution of the UF ranks with respect to the evaluation result values of the UF parameters is as follows.
It differs for each F parameter. For example, the color intensity (D) and other items (CV, E) are close to normal distribution, but the color breadth (SJ), color contrast (P) and contrast enhancement (PD) Has a biased distribution. Therefore, the evaluation result value of the UF parameter is uniformly converted to the UF rank,
After obtaining one value from the evaluation result value of the F parameter, UF
This is because conversion into a rank may impair the reliability, objectivity, and the like in the W-UF evaluation.

[Output of UF Evaluation] When the conversion into the UF rank is performed for each UF parameter, the computer device 2 then proceeds to the UF parameter conversion for each UF parameter as shown in FIG. Calculate the average value of the rank (S7
0). Thereby, the computer device 2 aims to unify the UF parameters.

Specifically, the converted UF rank is represented by Vuf
Then, the computer device 2 has the following (18)
This is calculated by the formula.

[0074]

(Equation 18)

In the equation (18), α to ζ are weighting coefficients for each UF parameter. The weighting coefficients may be all set to “1” equally, or may be individually determined based on empirical values such as experimental results. For UF parameters that do not need to be added to the W-UF evaluation result, the weighting coefficient may be set to “0”.

When the Vuf is calculated in this manner, the computer device 2 positions the calculation result as a W-UF evaluation result, and uses this as a display screen of the computer device 2 or a printer device (but not a (Not shown) or the like (S8).
0). At this time, in addition to the calculation of Vuf, the computer apparatus 2 may output the UF rank for each UF parameter to each UF parameter for reference.

As described above, according to the evaluation method and the evaluation apparatus in the present embodiment, when evaluating the W-UF of the color cathode ray tube 3 to be evaluated, the display on the display screen of the color cathode ray tube 3 Based on the chromaticity data obtained from 21 × 21 locations, quantification is performed on a plurality of UF parameters, and the evaluation result values of each UF parameter are converted into UF ranks. The result Vuf is calculated.

Therefore, if the W-UF of the color cathode ray tube 3 is evaluated using this evaluation method or evaluation apparatus,
Since a quantitative evaluation result can be obtained by calculating uf,
The evaluation can be performed without depending on the evaluator, which is suitable for managing the evaluation process and the like and grasping the transition over a long period of time. That is, by using this evaluation method or the evaluation device, an objective and highly reliable W-UF can be obtained.
Evaluation becomes possible.

Moreover, since the quantitative evaluation results are obtained through the quantification of a plurality of UF parameters, the multidimensional evaluation becomes possible, and the necessary and sufficient evaluation results in accordance with the actual situation become possible. Can be obtained. In other words, by performing evaluations based on multidimensional (multidimensional) indicators, while maintaining the quality of the evaluation at a high level,
It is possible to obtain an evaluation result according to the sensuality of a person who views the color cathode ray tube 3.

In quantifying each UF parameter, the color cathode ray tube 3 to be evaluated is
Is based on the chromaticity data obtained from 21 × 21 places on the display screen, so that it covers almost the entire area of the display screen,
Detailed quantification can be performed, and as a result, evaluation accuracy can be improved.

Further, when outputting Vuf as an evaluation result, if information on each UF parameter is output, more specifically, a UF rank for each UF parameter is also output, analysis of the evaluation result Vuf can be performed extremely. Can be made easier. For example, the output evaluation result V
If there is a problem with uf, which UF parameter has a problem (color strength (D) is bad, color width (SJ)
Is bad, etc.).

In this embodiment, color intensity (D), color breadth (SJ), color contrast (P), contrast enhancement (PD), and other (CV, E) are used as UF parameters. ), The case of quantifying the five items has been described as an example, but the present invention is not limited to this. For example, it is conceivable that a plurality of parameters are arbitrarily selected from these to be used as UF parameters, or UF parameters including items other than those exemplified above are used. Furthermore, it goes without saying that the order in which the UF parameters are quantified can be set arbitrarily.

In the present embodiment, the case where chromaticity data, which is the basis for quantifying each UF parameter, is obtained at 21 × 21 locations on the display screen of the color cathode ray tube 3 has been described. The invention is not limited to this. Regarding the location where the chromaticity data is obtained, the evaluation result Vuf
Accuracy, CCD camera 1 and computer device 2
May be determined in consideration of the data transfer load during the period.

Further, in the present embodiment, the W-UF evaluation, which is regarded as important for the evaluation of the color cathode ray tube, has been described as an example. However, the present invention is based on the UF evaluation for the screen uniformity of other colors. Even if there is, the present invention can be similarly applied. That is, by changing the setting of the reference value or the like at the time of quantifying the UF parameter, it can be applied to the UF evaluation for other colors.

[0085]

As described above, in the method and apparatus for evaluating the uniformity of a cathode ray tube according to the present invention, a plurality of evaluations are performed based on chromaticity data obtained from a display screen of a cathode ray tube to be evaluated. After calculating an evaluation result value for an item and converting it to a rank value, a uniformity evaluation value, which is one evaluation result, is calculated. Therefore, if an evaluation is performed using this evaluation method or evaluation apparatus, a quantitative evaluation result can be obtained by calculating the uniformity evaluation value, so that an objective and highly reliable uniformity evaluation can be performed.
In addition, when obtaining the quantitative evaluation results, since the evaluation result values for a plurality of evaluation items are used, multidimensional evaluation becomes possible, and it is in accordance with the sensuality of a person viewing the screen of the cathode ray tube. Necessary and sufficient evaluation results can be obtained with high accuracy.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of an embodiment of a method for evaluating the uniformity of a cathode ray tube according to the present invention, wherein (a) is a schematic flow and (b) is a flow of UF parameter quantification.

FIG. 2 is an explanatory diagram showing a schematic configuration of an example of an embodiment of a cathode ray tube uniformity evaluation apparatus according to the present invention.

FIG. 3 is an explanatory diagram showing a specific example of a chromaticity data acquisition location on a display screen of a cathode ray tube to be evaluated.

FIG. 4 is a schematic diagram illustrating the concept of color intensity (D).

FIG. 5 is a schematic diagram illustrating the concept of color contrast (P).

FIG. 6 is an explanatory diagram showing a specific example of a conversion table used when converting to a UF rank.

[Description of Signs] 1 ... CCD camera, 2 ... Computer device, 3 ... Color cathode ray tube

Claims (2)

[Claims] 1. A method for evaluating a uniformity of a cathode ray tube for evaluating a uniformity representing a color uniformity on a screen displayed by a cathode ray tube, wherein a display screen of the cathode ray tube to be evaluated is optically read, and Obtain chromaticity data at a predetermined location on the display screen from the read result, calculate evaluation result values for a plurality of evaluation items defined in advance based on the chromaticity data, and preset the calculated evaluation result values Converting the evaluation value into a rank value of the evaluation result according to the converted table, and calculating a uniformity evaluation value for the display screen of the cathode ray tube from the rank value of the plurality of evaluation items obtained by the conversion. Pipe uniformity evaluation method. 2. A cathode ray tube uniformity evaluation device for evaluating uniformity representing color uniformity on a screen displayed by a cathode ray tube, wherein the reading unit optically reads a display screen of the cathode ray tube to be evaluated. Chromaticity data obtaining means for obtaining chromaticity data at a predetermined location on the display screen from a result of reading by the reading means; and a plurality of chromaticity data defined in advance based on the chromaticity data obtained by the chromaticity data obtaining means. An evaluation result calculating means for calculating an evaluation result value for the evaluation item; a rank value converting means for converting the evaluation result value calculated by the evaluation result calculating means into a rank value of the evaluation result according to a preset conversion table; The uniformity evaluation value for the display screen of the cathode ray tube is obtained from the rank values of the plurality of evaluation items converted by the rank value conversion means. Calculated uniformity evaluation apparatus of a cathode ray tube, characterized in that it comprises a uniformity calculating means for.