JP2001128197A - Measuring instrument measuring device for crt focusing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten the correlation between the results of a focusing measuring instrument and visually evaluated results. SOLUTION: The focusing measuring instrument photographs a prescribed test pattern displayed on a CRT 6 by means of a CCD camera 3 and calculates the energy intensity distribution of the electron beam of the CRT 6 by using the photographed picture. Then the instrument discriminates whether the energy intensity distribution has a crest-like shape (appropriate), a trumpet-like shape having a widened foot (haloing trend), or bell-like shape having a trapezoid top (blooming trend) and evaluates the focusing of the CRT 6 based on the discriminated results. Since the instrument classifies the shape of the energy intensity distribution into shapes having high correlation with visual evaluation and evaluates the focusing of the CRT 6 based on the shapes, the correlation between the measured results of the instrument and visually evaluated results is heightened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CRT (Cathode
Ray Tube) displays a predetermined test pattern, and uses the image obtained by imaging the test pattern to display the CR.
The present invention relates to an apparatus for evaluating the focus performance of T.

[0002]

2. Description of the Related Art The focus performance of a CRT uses visual evaluation as a standard because the display content is recognized by human eyes.

In a CRT, predetermined information such as images and characters is displayed by emitting a predetermined phosphor out of a large number of phosphors discretely applied on the tube surface. For example, a predetermined character such as "E" is displayed, and the number of light-emitting phosphors included in the line width direction of the character and a luminance change at a line edge are visually evaluated. If the number of luminescent phosphors in the line width direction is small and the luminance change at the line edge is large and clear, the specified character is displayed sharply with a thin line. Be evaluated. On the other hand, if the line edge is clear but the number of luminescent phosphors in the line width direction is large, the predetermined character is displayed as a bold line, so that the focus state is evaluated as “overfocus” and the line width is evaluated. If the number of light-emitting phosphors in the direction is small, but the line edge is not clear, the character is displayed as if an umbrella was hung thereon, and the focus state is evaluated as "under-focus".

Conventionally, an apparatus for measuring the focus performance of a CRT has been commercialized for the purpose of speeding up and automating the evaluation of the focus performance of the CRT, reducing the evaluation variation by visual observation, and the like.

The focus performance measuring device of this CRT is C
A predetermined test pattern such as a line or a dot is displayed on the RT, the test pattern is imaged by an imaging device, and the energy intensity distribution of the electron beam of the CRT is calculated using the data of the imaged image. At a predetermined intensity level (e.g., 2
% Intensity level), and the focus performance of the CRT is evaluated based on this beam diameter.

According to the evaluation method of the focus performance measuring apparatus, the number of light-emitting phosphors in the line width direction differs between the just-focus state and the under-focus and over-focus states. Since it depends on the diameter, the focus performance of the CRT is evaluated based on the beam diameter of the electron beam.

[0007]

By the way, when a focus performance measuring device is introduced into the focus adjustment of a CRT, the quality of a display image on the CRT is judged by human eyes. It is not preferable that the evaluation is different from the visual focus performance evaluation.

However, the accuracy of the evaluation by the above-mentioned conventional focus performance measuring device is not sufficient, and may differ from the visual evaluation. In particular, when the focus performance is evaluated in a situation where electron beams having different energy intensity distribution shapes are mixed, the difference between the evaluation result and the visual evaluation tends to increase. This is because despite the fact that the energy intensity distribution of the electron beam has a three-dimensional distribution, the number of phosphors emitted and the amount of light emitted by each phosphor differ depending on the distribution, which greatly affects the focusing performance. It is considered that the conventional focus performance measuring apparatus evaluates the focus performance of the CRT only with the beam diameter at a specific relative intensity level of the electron beam.

Therefore, the conventional focus performance measuring apparatus has a certain limit in the accuracy of the focus performance evaluation, and it is difficult to obtain an evaluation having a higher correlation with the visual evaluation.

The present invention has been made in view of the above problems, and has as its object to provide a CRT focus performance measuring apparatus having high correlation with visual evaluation.

[0011]

According to a first aspect of the present invention, there is provided a pattern display means for displaying a predetermined test pattern on a CRT for focus performance evaluation, and a pattern display means arranged opposite to a display surface of the CRT to display the test pattern. Imaging means for imaging, intensity distribution calculating means for calculating the energy intensity distribution of the electron beam of the CRT using the image of the test pattern imaged by the imaging means, and CRT based on the shape of the energy intensity distribution And a determination means for determining the focus performance of the camera.

According to the above configuration, the predetermined test pattern displayed on the CRT is imaged by the imaging means, and the energy intensity distribution of the electron beam of the CRT is calculated using the data of the captured image.

Then, the focus performance of the CRT is determined based on the shape of the energy intensity distribution. That is, since the energy intensity distribution of the electron beam generally has a mountain-like shape like a Gaussian distribution, the calculated energy intensity distribution has a sharper peak at the peak and a wider flank than the standard mountain-like shape. It is determined whether the CRT has a shape like a bell or a bell-shaped shape in which a foot portion is narrowed and a mountaintop portion spreads like a trapezoid, and the focus performance of the CRT is determined based on the result of the identification.

For example, when a white line is displayed on a black background, when the energy intensity distribution is a standard chevron shape, the number of phosphors in the line width direction which emits light by irradiation with an electron beam is appropriate, and Since the brightness change is also good,
A line having a predetermined line width is sharply displayed, and the focus performance is determined to be good.

On the other hand, when the energy intensity distribution is trumpet-shaped, the number of phosphors in the line width direction is relatively appropriate, but the luminance change at the edge becomes unclear, and the line with the predetermined line width is blurred. Is displayed in a state where
Such a display tendency is called a halo tendency. The focus performance is determined according to the degree of the halo tendency.
When the energy intensity distribution has a bell-shaped shape, the luminance change at the edge portion is relatively good, but the number of phosphors in the line width direction increases, and the phosphor is displayed as a line wider than the predetermined line width. (Hereinafter, such a display tendency is referred to as a blooming tendency.) The focus performance is determined according to the degree of the blooming tendency.

The invention according to claim 2 is the invention according to claim 1,
In the focus performance measuring apparatus of the RT, the determination means includes a first beam diameter at a predetermined first intensity level of the energy intensity distribution and a predetermined second intensity higher than the first intensity level. Beam diameter ratio calculating means for calculating a ratio with the second beam diameter at the level;
CRT based on the shape of the energy intensity distribution determined by the beam diameter ratio calculated by the beam diameter ratio calculating means
Is to determine the focus performance of the camera.

According to the above configuration, the first beam diameter BSh at the first intensity level of the energy intensity distribution (that is, the beam diameter at the foot portion) and the predetermined second intensity higher than the first intensity level. A beam diameter ratio R = BSb / BSh with respect to the second beam diameter BSb at the level (that is, the beam diameter at the peak) is calculated, and the shape of the energy intensity distribution of the electron beam is determined based on the calculation result. .

That is, when the beam diameter ratio R when the energy intensity distribution is a standard chevron shape is TP, R is TP
As the size becomes larger, the shape is determined to have a strong blooming tendency, and as R becomes smaller than TP, the shape is determined to have a strong halo tendency. The focus performance is determined based on the shape of the energy intensity distribution determined by the shape determination.

The third aspect of the present invention provides the first aspect of the present invention, wherein
In the RT focus performance measuring device, the discriminating means includes a center of gravity calculating means for calculating a vertical center of gravity of the energy intensity distribution, and the shape of the energy intensity distribution determined by the center of gravity calculated by the center of gravity calculating means Is used to determine the focus performance of the CRT.

According to the above configuration, the vertical center of gravity of the energy intensity distribution is calculated, and the shape of the energy intensity distribution is determined based on the calculation result. The vertical center of gravity of the energy distribution is defined by the coordinate value in the energy intensity direction of a fulcrum where the cross-sectional shape is the same as the energy distribution when the same object is lifted, and the object lays right next to it, as shown in FIG. Energy intensity distribution peak value 100
When normalized such that

[0021]

(Equation 2)

If the shape of the energy intensity distribution is bell-shaped, the center of gravity G will be large, and if the shape of the energy intensity distribution is trumpet-shaped, the center of gravity G will be small. Assuming that the center of gravity is TP, as the center of gravity G becomes larger than TP, the shape is determined to have a stronger tendency to bloom, and as the center of gravity G is smaller than TP, the shape is determined to be more likely to have a halo tendency. The focus performance is determined based on the shape of the energy intensity distribution determined by the shape determination.

The invention according to claim 4 is the invention according to claim 1,
In the RT focus performance measuring device, the shape of the energy intensity distribution is approximated by a function expressed by the following equation (1), and the focus performance of the CRT is determined based on the shape of the energy intensity distribution determined by the approximate function. Is what you do.

[0024]

(Equation 3)

According to the above configuration, the function f shown in the equation (1)
An approximate function indicating the shape of the energy intensity distribution is calculated using (r). Specifically, assuming that the order of the standard chevron shape is Nr, the function f (r) becomes a shape having a strong blooming tendency according to the order N when the order N becomes larger than Nr, and the order N becomes Nr. When the size is smaller, the shape becomes a shape having a strong halo tendency according to the order N. Therefore, by determining the order N, an approximate function indicating the shape of the energy intensity distribution can be obtained. Then, the focus performance is determined based on the shape of the energy intensity distribution determined by the approximate shape.

According to a fifth aspect of the present invention, in the apparatus for measuring the focus performance of a CRT according to any one of the first to fourth aspects, the discriminating means determines whether or not the energy intensity distribution has a peak position or a position near the peak position. The focus performance of the CRT is determined on the basis of at least one of the shapes.

According to the above configuration, the shape of at least one of the left and right sides of the peak position or the vicinity of the peak position of the energy intensity distribution is determined, and the focus performance of the CRT is determined based on the shape of one side. .

According to a sixth aspect of the present invention, in the CRT focus performance measuring apparatus according to any one of the first to fifth aspects, the discriminating means includes a predetermined first intensity of the energy intensity distribution. Beam diameter calculating means for calculating a first beam diameter at the first level and a second beam diameter at a predetermined second intensity level higher than the first intensity level, wherein the shape of the energy intensity distribution and the second The focus performance of the CRT is determined based on the first and second beam diameters.

According to the above configuration, the beam diameters BSh, BSb for the first and second intensity levels of the energy intensity distribution.
Is calculated, and the focus performance of the CRT is determined based on these calculation results and the shape of the energy intensity distribution.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A CRT focus performance measuring apparatus according to the present invention will be described with reference to the drawings.

The CRT focus performance measuring apparatus according to the present invention is obtained by displaying a predetermined test pattern such as a dot pattern, a line pattern, and a cross hatch pattern on a CRT to be evaluated, and imaging the test pattern with an imaging device. A cross-sectional shape (hereinafter, referred to as a beam profile) of the energy intensity distribution of the electron beam of the CRT is calculated using the image data, and further, it is determined to which of a plurality of pre-classified shapes the beam profile belongs. The focus performance is evaluated based on the determination result.

That is, although the beam profile is generally mountain-shaped (see FIG. 2), visual evaluation of the focus performance of the CRT uses only the beam diameter of the cross section of the beam profile (hereinafter, the beam diameter is referred to as the beam size). In addition, since the influence of the shape of the beam profile itself is great, the focus performance measuring device of the CRT according to the present invention changes the shape of the beam profile to a standard that is visually evaluated as having good focus performance as shown in FIG. Based on the shape of the chevron, the peaks are standard, but the skirts tend to spread, and the skirts are standard, but the peaks tend to spread in a trapezoidal shape and classified into multiple stages, Visual evaluation in each class is associated, and visual evaluation is performed according to which class the shape of the actually measured beam profile belongs to. It is intended to evaluate the high correlation focusing performance.

As shown in FIG. 2, as the beam profile becomes a trumpet shape in which the foot portion is widened, the thickness of the display dot does not change much at the center, but the brightness change at the edge portion becomes slow, and Is displayed (blurred display). Such a tendency is called a halo tendency, and the focus adjustment determines that the state is “under-focus” with respect to an appropriate focus state.

On the other hand, as the beam profile becomes more bell-shaped with the peak at the top, the brightness of the display dot does not change much at the edge, but the thickness at the center becomes larger and the display dot becomes wider than necessary. Become. Such a tendency is called a blooming tendency, and the focus adjustment determines that the state is “over-focus” with respect to an appropriate focus state.

FIG. 3 is a block diagram of a measuring system of the focus performance measuring device of the CRT.

The focus performance measuring device 1 comprises a data acquisition control unit 2, a CCD camera 3, a signal generator 4 and a measurement control unit 5, and the CCD camera 3, signal generator 4 and measurement control unit 5 are not shown. Is connected to the data acquisition control unit 2 by a cable of Note that the data capture control unit 2
Is communicably connected to the measurement control unit 5. The focus performance evaluation measurement system is a color CRT 6 to be measured.
Are connected to the data acquisition control unit 2 by a cable (not shown).

The CCD camera 3 is for detecting the luminance of light emitted when the phosphor arranged on the display surface of the color CRT 6 emits light by the irradiation of the electron beam. CC
As shown in FIG. 5, the D camera 3 includes, for example, a photographing lens 7,
Half mirror 8, two CCD line sensors 9A, 9B
And an optical system composed of two cylindrical lenses 10A and 10B.

In the optical system shown in FIG. 2, a CCD line sensor 9A for evaluating focus performance when a vertical line test pattern is displayed on the display surface of the color CRT 6, and a horizontal line test pattern on the same display surface. A CCD line sensor 9B for evaluating focus performance when displaying is provided. It should be noted that not only the CCD solid-state imaging device but also the imaging device of the CCD camera 3 is used.
A MOS type solid-state imaging device may be used.

The CCD line sensor 9A is arranged so that its axial direction is parallel to the horizontal direction with respect to the display surface of the color CRT 6, and the CCD line sensor 9B is arranged so that its axial direction is vertical with respect to the display surface of the color CRT 6. It is arranged so that it may become parallel. The CCD camera 3 can perform exposure control according to an arbitrary shutter speed by controlling the charge accumulation time of the CCD line sensors 9A and 9B.

It should be noted that a CCD area sensor can be used instead of the CCD line sensors 9A and 9B as the image pickup device. The use of a CCD area sensor has the advantages of simplifying the configuration of the imaging device and reducing the number of times of imaging.

In FIG. 5, the photographing lens 7 has a color CR.
The image G of the test pattern displayed on the display surface of T6 is C
The image is formed on the imaging surface of the CD line sensors 9A and 9B. This imaging lens 7 may be constituted by a zoom lens whose optical magnification can be detected. If the zoom ratio can be changed, there is an advantage that the range of the measurable phosphor pitch is widened. The half mirror 8 separates the light image transmitted through the photographing lens 7 into two, and transmits one to the CCD line sensor 9A side and reflects the other to the CCD line sensor 9B side. The half mirror 8 is disposed at an appropriate position on the optical axis of the photographing lens 7, a CCD line sensor 9 A is disposed at an appropriate position behind the half mirror 8, and a CCD line sensor 9 B is disposed at an appropriate position below the half mirror 8. .

Each of the cylindrical lenses 10A and 10B apparently enlarges an imaging range in a direction perpendicular to the line direction of the CCD line sensors 9A and 9B (hereinafter, this direction is referred to as a sensor width direction). That is, as shown in FIG. 6, the CCD line sensor 9A,
The imaging range A on the display surface of the 9C color CRT 6 is L
Assuming that (longitudinal direction) × W (width direction), the imaging range A of the CCD line sensors 9A and 9B is apparently W ′ (> W).
Is enlarged to an imaging range A ′ having the following dimensions.

As described above, the CCD line sensors 9A and 9B
Is apparently optically enlarged in the sensor width direction because, when a vertical line is displayed on the display surface of a CRT, the line width of the vertical line is uneven due to a vertical raster pitch. However, the line width of the vertical line varies depending on the imaging position of the CCD line sensor 9A, and the measured value of the beam profile may differ. Therefore, by expanding the apparent imaging range A in the sensor width direction, the profile measurement value This is to reduce measurement errors.

In a CRT manufacturing process, focus adjustment is generally performed while visually observing a predetermined test pattern displayed on the CRT. The human eye observes the test pattern by averaging those irregularities even if the line width of the test pattern has irregularities.
Is evaluated based on a display image of a test pattern having an average line width.

When a focus performance measuring device is introduced into the focus adjustment of the CRT, if the measurement result of the beam profile is different from the conventional evaluation state of the test pattern visually, the result of the focus performance evaluation based on the beam profile is different from the visual evaluation. It will be different and not preferable.

Therefore, in the present embodiment, the light receiving range W of each pixel of the CCD line sensors 9A and 9B is set to be at least equal to or longer than the vertical raster interval Pv of the electron beam Bm or the vertical direction of the phosphor included in the vertical line. The light receiving range W 'is optically enlarged to the light receiving range W' which is equal to or longer than the arrangement pitch interval, and the light emission amount of the plurality of phosphors included in the light receiving range W 'is integrated and received at each pixel.

Therefore, since the imaging range A of the CCD line sensors 9A and 9B is apparently expanded in the sensor width direction, the CCD line sensors 9A and 9B for the vertical line pattern
Even if the imaging positions of A and 9B are set to arbitrary positions on the CRT display surface, the beam profiles calculated at the respective imaging positions are substantially the same, and focus performance evaluation with little repetition error and high correlation with visual evaluation is achieved. You can get it.

The aperture grill type color C
In RT, in the beam profile measurement for the horizontal line pattern, the line direction of the CCD line sensor 9A matches the width direction of the horizontal line, and
Since the continuous profile of the horizontal line can be calculated directly from the output signal from A, the influence of the unevenness of the line width is smaller than the profile measurement for the vertical line pattern, and the cylindrical lens 10B can be omitted. It is.

However, in the present embodiment, the CCD line sensor 9B is supported in consideration of profile measurement for a horizontal line pattern in a round or slot type shadow mask type CRT and focus performance evaluation based on the measurement result. In addition, a cylindrical lens 10B is provided. Also, in the profile measurement for the horizontal line pattern in the aperture grill type CRT, the light receiving range in the sensor width direction of each pixel of the CCD line sensor 9B is optically enlarged by providing the cylindrical lens 10B, and the output signal from each pixel is output. There is an advantage that the S / N ratio of can be improved. Therefore, C
By optically increasing the pixel density in the line width direction of the CD line sensors 9A and 9B, high-resolution and high-accuracy profile measurement is possible, and suitable focus performance evaluation is possible.

Returning to FIG. 3, the color CRT 6 to be evaluated is an electromagnetic deflection color CRT, a color cathode ray tube 61 for displaying an image, a first drive control circuit 62 for controlling the driving of the color cathode ray tube 61 with respect to the displayed image, and a color cathode ray tube. A second drive control circuit 63 is provided to control the drive related to the display range (raster size) 61.

As shown in FIG. 7, the color cathode ray tube 61 has striped R (red), G (green), and B (blue) phosphors Fr, regularly arranged in the horizontal direction on the back surface of the face plate. The fluorescent surface 611 is formed by baking Fg and Fb. A blind grid type aperture grill 61 is provided at a predetermined interval in front of the fluorescent screen 611 in the cathode ray tube.
2 are provided. In the electron gun mount 613, three electron guns 614 are provided corresponding to the respective colors of R, G, and B, and a deflection yoke 615 is provided outside the tip of the electron gun mount 613.

The first drive control circuit 62 generates an electron beam Bm corresponding to each of the colors R, G, and B emitted from the electron gun 614.
(The shape of the beam cross section and the electron energy intensity distribution in the cross section). First
The drive control circuit 62 controls the drive of the electron gun 614 based on the beam control signal (video signal) input from the data capture control unit 2.

The second drive control circuit 63 controls raster scanning of the fluorescent surface 611 of the electron beam Bm and its scanning range (irradiation range). Second drive control circuit 63
Controls the display position of the electron beam Bm emitted from the electron gun 614 based on a raster size control signal (deflection control signal) input from the data acquisition control unit 2.

The data acquisition control unit 2 controls acquisition of data necessary for measuring the profile of the beam profile, calculates a beam profile using the acquired image data, and further evaluates the focus performance based on the profile. Things.

In the focus performance measuring apparatus 1 according to the present embodiment, profile measurement is performed by the same method as described in, for example, JP-A-11-234708. That is, when a dot pattern is used, for example, first, as shown in FIG. 8, a dot pattern composed of a plurality of dots D1, D2,... Is formed on the display screen of the color CRT 6 by adjusting the raster size of the color CRT 6. The phosphors F (j) (j = j) in the dots Di (i = 1, 2,...)
(1, 2,...) Are displayed in different sizes, and the dot pattern is imaged by the CCD camera 3. Then, the light emission position of the phosphor F (i, j) and the brightness level C (i, j) within the dot are calculated from the captured image for each dot Di (see FIG. 8B). The luminance level C (i, j) of the light emitting phosphor is rearranged based on the light emitting position to calculate the line profile P '(FIG. 8).
(C)).

Therefore, the data capture control unit 2 sets the color CR
The test pattern displayed on the T6 is captured by the CCD camera 3, and the raster size control signal is output to the color CRT 6 while confirming the display size of the test pattern using the captured image, and the test pattern displayed on the color CRT 6 is displayed. Change the display size of. Then, when the display size of the test pattern becomes a desired size, the output of the raster size control signal is stopped to adjust the display size of the test pattern. Thereafter, the data acquisition control unit 2
Captures a test pattern for profile measurement, and performs a beam profile calculation process using the captured image.

FIG. 4 is a block diagram of the data acquisition control unit 2 of the focus performance measuring device 1.

The data acquisition control unit 2 includes an A / D converter 21
VRAM (Video Random Access Memory) 22, RAM
(Random Access Memory) 23, ROM (Read Only Me)
mory) 24, control unit 2 consisting of a microcomputer
5, synchronization signal delay unit 26, horizontal / vertical synchronization signal detection unit 2
7 and a communication unit 28. The A / D converter 2
1 may be provided in the CCD camera 3.

The A / D converter 21 converts an image signal (luminance signal captured by each pixel of the CCD line sensors 9A and 9B) sent from the CCD camera 3 into a digital signal of, for example, 12-bit data. is there. VRAM2
Reference numeral 2 denotes a memory for storing a pixel signal (hereinafter, referred to as pixel data) that has been A / D converted into a digital signal by the A / D converter 21. The VRAM 22 is a CCD line sensor 9A,
It has a storage capacity capable of storing the line image captured in 9B.

The ROM 24 is a memory storing a control program for performing profile measurement and focus performance evaluation based on the profile. RAM2
3 indicates that the control unit 25 controls the VRAM 22 according to the control program.
Provides a storage area (work area) for performing a series of arithmetic processing using the pixel data stored in the.

The control section 25 centrally controls the operation of each section in the data acquisition control section 2. The control section 25 controls the display of the test pattern on the color CRT 6, the imaging of the test pattern by the CCD camera 3, and the imaging of the test pattern. The beam profile is calculated using the image, and the focus performance is evaluated based on the shape of the beam profile.
Further, the control unit 25 performs data communication with the measurement control unit 5 via the communication unit 28, and outputs the calculation result of the beam profile and the evaluation result of the focus performance to the measurement control unit 5.
In the measurement control unit 5, the calculation result of the beam profile and the focus performance evaluation result are displayed on the display unit 52 by a predetermined display program.

The control unit 25 internally includes a profile calculation unit 251, a center-of-gravity calculation unit 252, a shape determination unit 253, a size determination unit 254, and a focus performance evaluation unit 255 in order to evaluate the focus performance using the captured image of the test pattern. Of each processing block. These processing blocks 251 to 255 illustrate main processing functions processed by executing a processing program described later as processing blocks.

The profile calculation unit 251 calculates a beam profile using the captured image of the test pattern. The calculation method of the beam profile will be described later.

The center of gravity calculating section 252 is the profile calculating section 2
The vertical gravity center G of the beam profile calculated in 51 is calculated. As described above, the vertical center of gravity G of the beam profile is defined by the above equation (2), but in the actual center of gravity calculation, the following equation (3) is obtained by replacing the integration processing with the integration processing. Therefore, the center-of-gravity calculating unit 252 calculates the vertical center of gravity G of the beam profile using the relative luminance level (corresponding to the energy intensity) of each light-emitting position constituting the beam profile by the following equation (3). Needless to say, the smaller the integrated pitch of the energy intensity k, the higher the calculation accuracy of the center of gravity G.

[0065]

(Equation 4)

The profile data calculated by the profile calculation unit 251 is constituted by data of the relative luminance level of the light emitting phosphor sampled at a predetermined pitch, and the energy intensity k cannot be obtained at a desired integrated pitch. Since there is no, when trying to apply the above formula (3),
It is necessary to calculate the energy intensity k of a term that is insufficient as an integrated value and the beam diameter BS (k) at the energy intensity k, which lowers the calculation efficiency. Therefore, the center of gravity G is directly calculated using the energy intensity actually measured by the following equation (4).
May be calculated.

[0067]

(Equation 5)

The shape judging section 253 judges the shape of the beam profile based on the vertical center G calculated by the center calculating section 252. That is, it is determined whether the beam profile has a trumpet-like shape (halo-like shape) or a bell-like shape (blooming-like shape). FIG. 9 shows the relationship between the focus performance evaluation by visual observation and the vertical center of gravity G of the beam profile. As shown in FIG. As the strength becomes stronger, the vertical center of gravity G becomes smaller, and as the blooming tendency becomes stronger, the vertical center of gravity G becomes larger. This is because if the beam profile is trumpet
Since the low-level energy intensity is distributed over a wide range of the skirt portion, the vertical center of gravity G decreases according to the spread of the skirt portion. If the beam profile is bell-shaped, the high-level energy intensity at the summit portion increases. This is because, because of the wide distribution, the center of gravity G in the vertical direction increases in accordance with the spread of the flat portion of the peak.

Accordingly, the shape determining section 253 is provided with the center-of-gravity calculating section 2
The vertical center of gravity G calculated in 52 is set to a predetermined threshold T.
Compared with P (the center of gravity in the vertical direction when judged as good by visual focus performance evaluation), if G <TP, the profile is judged to be a trumpet-shaped (halo-shaped) and G> TP If there is, the profile is determined to be a bell-shaped shape (a shape having a tendency to blooming). Furthermore, as shown in Table 1 below, when the profile has a halo tendency, the shape determination unit 253 compares the degree of the halo tendency with five threshold values TGh1 to TGh4 set in advance in a range smaller than the threshold value TP. When the profile is classified into ranks A to E and the profile has a blooming tendency, four thresholds T set in advance are set.
The degree of blooming tendency is 5 compared to Gb1 to TGb4.
Are classified into three ranks A to E.

[0070]

[Table 1]

The size judging section 254 judges the size of the profile based on the beam diameter (that is, the beam size) at a predetermined relative luminance level of the profile calculated by the profile calculating section 251 (how much the halo tendency and the blooming tendency are). (Determination as to whether or not they have the size). The shape determination unit 253 classifies the profile shape based on the vertical center of gravity G based on the halo tendency or the blooming tendency. However, the size determination unit 254 determines the profile of a predetermined luminance level set in advance according to the shape determination result. The beam diameter BSh or the beam diameter BSb (> BSh) is calculated, and the beam diameter BSh is calculated.
(Or BSb) to classify the shape of the beam profile. In other words, if it is a halo tendency, how much the base of the profile is widened,
If it is a blooming tendency, the degree of flatness of the peak portion is classified in multiple stages, and the shape of the beam profile is finely classified based on the beam size.

In the present embodiment, as shown in FIG. 10, when the profile shape has a halo tendency, the beam diameter BSh at a relative luminance level of 2% with respect to the peak value is calculated. As shown, the beam diameter BSh is compared with four preset threshold values TSh1 to TSh4, and the degree of halo tendency is classified into five ranks A to E. When the profile shape has a blooming tendency, the peak value is obtained. A beam diameter BSb at a relative luminance level of 50% is calculated, and the beam diameter BSb is compared with four preset thresholds TSb1 to TSb4 as shown in Table 2 (b) below to determine the degree of blooming tendency. Are classified into five ranks A to E. In Table 2, the threshold values TSh1 to TSh1
TSh4, BSb1 to BSb4 are TSh4>TSh3>TSh2> T
Sh1, BSb4>BSb3>BSb2> BSb1.

[0073]

[Table 2]

FIG. 10 is a diagram showing an example of the ranking of the beam profiles shown in Tables 1 and 2 by the vertical center of gravity G and the beam diameter BS.

In the figure, the horizontal axis indicates the vertical center of gravity G,
The vertical axis indicates the beam diameter BS. The upper left area A shows the ranking area of the beam profile having a halo tendency, and the lower right area B shows the ranking area of the beam profile having a blooming tendency. Vertical lines dividing the regions A and B are threshold values TGh1 to TGh4, TG of the vertical center of gravity G.
b1 to TGb4, and the horizontal line represents the threshold value TSh1 to
TSh4, TSb1 to TSb4. The curve is a typical beam diameter BSh at a relative luminance level of 2%, and the curve is a typical beam diameter BSh at a relative luminance level of 50%.
It is.

When the beam profile has a halo tendency,
The beam diameter BSh of the relative brightness level of 2% of the beam profile is distributed around the curve, and in the case of blooming, the beam diameter BSb of the relative brightness level of 50% of the beam profile is distributed around the curve.
The setting of the rank values RG and RS according to Tables 1 and 2 corresponds to determining in which small area in the areas A and B the vertical center of gravity G and the beam size BS are distributed.

In the visual evaluation, the focus performance is
For example, since the evaluation is performed in 13 steps in which ± is added to the five-step evaluation of A to E, each of the small areas in the areas A and B is associated with the visual evaluation so that the shape of the beam profile has a high correlation with the visual evaluation. Evaluation values are obtained. In the present embodiment, as described later, final focus performance evaluations are arranged and output into two types of “good (adjustment not required)” and “bad (adjustment required)” based on the necessity of focus adjustment. I have to.

In the conventional focus performance measuring apparatus, the beam diameter BSh at a relative luminance level of 2% of the beam profile is used.
Alternatively, since the focus performance evaluation was performed only with the beam diameter BSh of the relative luminance level of 50%, for example, 2%
When the evaluation is made with the beam diameter BSh of the relative luminance level, it is difficult to distinguish between the halo system and the blooming system depending on the beam diameter BS, as is apparent from the curve in FIG. However, in this embodiment, the shape of the beam profile is more finely classified based on the vertical center of gravity and the beam diameter at a predetermined relative luminance level, and is associated with the visual evaluation. The evaluation can be performed with higher accuracy than the performance evaluation.

The beam profile calculated by the profile calculator 251 is obtained by arranging the relative levels of a plurality of light emitting phosphors at a predetermined sampling pitch as shown in FIG. Alternatively, a sampling position for a relative luminance level of 50% does not always exist. That is, as for the sampling position for a relative luminance level of 2%, for example, in FIG. 11, the luminance data of the luminescent material constituting the beam profile P does not always include the luminance data of the sampling positions ra and rb. It is not always possible to directly calculate the beam diameter BSh (= rb−ra) at a relative luminance level of 2% from the profile data. This is the same for the beam diameter BSh at the relative luminance level of 50%.

Therefore, in the present embodiment, FIG.
The relative brightness to the right of the peak value
Sampling position r corresponding to level C_RIs the relative
Two relative luminance levels C sandwiching the luminance level C_R1, C_R2To
Corresponding sampling position r _R1, R_R2Calculate using
Along with the relative brightness to the left of the peak value.
Sampling position r corresponding to degree level C_LThe relevant phase
Two relative luminance levels C sandwiching the luminance level C_L1, C_L2
Sampling position r corresponding to_L1, R_L2Calculated using
And BS = p · (r_R-R_L(5) Beam diameter at relative luminance level C to be obtained by equation (5)
The BS is calculated. The expression (5)
Where p is the sampling pitch and is several tens of μm in size.
You.

As for the sampling position r _R, the profile change between the sampling position r _R1 and the sampling position r _R2 is regarded as a straight line, and the straight line (the relative luminance level C _R1 and the relative luminance A straight line connecting the level C _R2 ) is calculated as a position corresponding to a point C _R that intersects the relative luminance level C.

[0082]

(Equation 6)

Similarly, regarding the sampling position r _L , the profile change between the sampling position r _L1 and the sampling position r _L2 is regarded as a straight line, and as shown in the following equation (7),
The straight line (a straight line connecting the relative luminance level C _L1 and the relative luminance level C _L2) is calculated as the position corresponding to the C _L point which intersects the relative luminance level C.

[0084]

(Equation 7)

Therefore, by substituting the above equations (6) and (7) into the above equation (5), the beam diameter BS at the desired relative luminance level C is calculated by the following equation (8).

[0086]

(Equation 8)

The focus performance evaluation unit 255 evaluates the focus performance based on the profile shape, that is, the shape determination result (rank value RG) by the shape determination unit 253 and the size determination result (rank value RS) by the size determination unit 254. It is what you do. Focus performance evaluation unit 2
Reference numeral 55 denotes a focus performance evaluation table using the rank values RG and RS shown in Table 3 below as parameters. The focus performance is evaluated based on the profile shape using the evaluation table.

[0088]

[Table 3]

Returning to FIG. 4, the synchronizing signal delay unit 26 delays the horizontal synchronizing signal and the vertical synchronizing signal of the pattern signal output from the signal generator 4 by a predetermined time specified by the control unit 25, and rasterizes the color CRT 6. The size is changed, and thereby the size of the test pattern displayed on the color CRT 6 is changed.

The horizontal / vertical synchronization signal detector 27 detects the horizontal synchronization signal and the vertical synchronization signal output from the signal generator 4. This detection signal is output from the CRT on the CRT display surface.
It is used for shutter control of the CCD camera 3 in order to capture the light emission of the phosphor at the timing at which the phosphor at the imaging position of the CD camera 3 emits light.

The communication unit 28 includes the CCD camera 3 and the color C
It controls transmission of a drive control signal to the RT 6 and data communication with the measurement control unit 5. Also, the signal generator 4
Is for generating a pattern signal (video signal) for generating a predetermined test pattern on the color CRT 6. The signal generator 4 outputs a video signal, a vertical synchronizing signal, and a horizontal synchronizing signal indicating the contents of the pattern, and displays a predetermined test pattern on the color CRT 6. The signal generator 4 changes the display timing and the display pattern according to an instruction from the control unit 25.

Returning to FIG. 3, the measurement control unit 5 includes a control unit 51 comprising a personal computer and a display 52 such as a CRT.
And a keyboard 53 for controlling the operation of the focus performance measuring device 1 and displaying the beam profile and the focus performance evaluation calculated by the data acquisition control unit 2 on the display 52. The measurement control unit 5 has a dedicated focus performance evaluation processing program, and causes the focus performance measurement device 1 to perform profile measurement and focus performance evaluation based on the shape of the beam profile according to the processing program. Is displayed on the display unit 52 in a predetermined display format.

Next, the focus performance evaluation processing by the focus performance measuring device 1 will be described with reference to the flowcharts of FIGS. FIG. 13 is a flowchart showing a procedure for evaluating the focus performance.
4 is a flowchart showing a procedure of profile measurement.

First, data of the relative luminance level constituting the beam profile is created (# 1). This profile data is created by measuring the beam profile of the electron beam according to the flowchart shown in FIG. The beam profile measuring method according to the present embodiment is the same as the method described in JP-A-11-1340708. Therefore, the beam profile measurement will be briefly described here.

First, a test pattern composed of a plurality of dots is displayed on the color CRT 6 in a predetermined size such that the light emitting positions of the light emitting phosphors in each dot are different from each other as shown in FIG. (# 21). Note that FIG.
In (a), the vertical band is the phosphor F (k) (k = 0,
1,...), And circles indicate dots D (i) (i = 1, 2,...) Displayed by electron beam irradiation.

The display size of the test pattern is, for example, a stripe pattern caused by the phosphor emission contained in the dot D (1) and a stripe pattern caused by the phosphor emission contained in the dot D (10) in FIG. This is done by changing the horizontal raster size of the color CRT 6 so that

Subsequently, when the test pattern is displayed in a predetermined size, the test pattern is imaged by the CCD camera 3 (# 23), and 10 images are taken from the image as shown in FIG. For the display dots D (1) to D (10), the relative luminance levels C (i, j) (i = 1, 2,... 10, j = 1, 1) of the light-emitting phosphor F (k) in each dot. 2, 3) are calculated (# 25). The luminance level C (i, j) is the j-th phosphor F (k) from the left among the plurality of phosphors F (k) included in the i-th dot D (i). Is the relative luminance level.

Subsequently, the calculated relative luminance level C (i,
By rearranging j) based on the light emission position in each dot, a beam profile is calculated as shown in FIG. 16 (# 27).

When the data of the relative luminance level C (i, j) constituting the beam profile is created, subsequently, using the relative luminance level C (i, j), the above equation (3) or (4) is used. ), The vertical center of gravity G of the beam profile is calculated (# 3), and the vertical center of gravity G and the thresholds TP,
In comparison with TGh1 to TGh4 and TGb1 to TGb4,
RG (A to A)
E) is determined, and it is determined whether the beam profile has a halo type or a blooming type (# 5, # 7).

If the beam profile has a halo type shape as determined by the shape determination (YES in # 9), the beam diameter BS at a relative luminance level of 2% of the beam profile is further obtained.
h is calculated (# 11), and the beam diameter BSh and the threshold value TS are calculated.
By comparing h1 to TSh4, the rank values RS (A to E) of the beam size in the halo tendency are determined according to Table 2 (a) (# 13). On the other hand, if the beam profile has a blooming type shape by the shape determination (# 9)
NO), the beam diameter BSb at a relative luminance level of 50% of the beam profile is calculated (# 15), and the beam diameter BSb is compared with the threshold values TSb1 to TSb4 to obtain the values in Table 2 above.
According to (b), the rank values RS (A to E) of the beam size in the blooming tendency are determined.

The evaluation value of the focus performance is determined from the evaluation table of Table 3 using the rank value RG of the shape and the rank value RS of the beam size (# 19).
That is, when the rank value RG of the shape and the rank value RS of the beam size are a combination of the D rank and the E rank, the focus performance is evaluated as “NG (poor)”,
In cases other than the combination of the rank and the E rank, the focus performance is evaluated as “OK (good)”.

Incidentally, it is possible to evaluate in 25 steps by a combination of the rank value RG of the shape and the rank value RS of the beam size. In Table 3, the quality is evaluated based on whether the focus adjustment is finally required or not. Since the evaluation is performed, in Table 3, when the rank value RG of the shape and the rank value RS of the beam size are a combination of the D rank and the E rank, the focus performance is determined to be uniformly poor and the combination of the D rank and the E rank is determined. In other cases, the focusing performance is uniformly good.

As described above, in the visual evaluation, the focus performance evaluation is, for example, 1 in which ± is added to five levels of A to E.
Since the evaluation is performed in three stages, in the focus performance measuring device 1 according to the present embodiment, the evaluation based on the combination of the rank value RG of the shape and the rank value RS of the beam size corresponds to the visual evaluation in a plurality of stages. The result may be output. In such a case, in Table 3, 13 columns of ranks in which ± are assigned to A to E of the visual evaluation are assigned to each column of the matrix, so that the focus performance evaluation is a rank value in which ± is assigned to A to E ( For example, A, A
⁺ , A ^- etc.).

As described above, in the focus performance measuring apparatus 1 according to the present embodiment, a predetermined test pattern is displayed on the color CRT 6, and the test pattern is picked up by the CCD camera 3 to obtain an electron beam. Calculate the beam profile, which is the energy intensity distribution, and classify the shape of the beam profile into a halo system and a blooming system based on the vertical center of gravity G, and determine the degree of each system by the beam diameter BS at a predetermined relative luminance level. Since the focus performance is shown based on the rank value and the focus performance is evaluated based on the rank value, the focus performance evaluation having a high correlation with the visual evaluation can be performed by associating the rank value with the visual evaluation value.

FIG. 17 and FIG. 18 are diagrams showing an example of examining the correlation between the evaluation of the measuring instrument and the visual evaluation. FIG. 17 is for a green display screen, and FIG. 18 is for a red display screen. In both figures, (a) shows the correlation with the visual evaluation when only the beam size for the relative luminance level of 2% is evaluated, and (b) shows the correlation only with the beam size for the relative luminance level of 50%. FIG. 7C is a diagram showing a correlation with a visual evaluation in the case of evaluation, and FIG. 7C shows a correlation with a visual evaluation in a case where the shape of a beam profile is ranked and evaluated based on the vertical luminance G and the beam size BS according to the present embodiment. FIG.

As shown in FIGS. 17 and 18, in both the green display screen and the red display screen, in the conventional method of performing the focusing performance only with the beam size, there are many cases in which the evaluation is out of the line of the coincidence, and the visual evaluation is performed. Although the correlation with the evaluation is not high, in the method according to the present invention, almost everything is gathered on the straight line where the evaluation is consistent, and it can be seen that the correlation with the visual evaluation is high.

FIGS. 19 and 20 are diagrams showing an example in which the evaluation by the focus performance measuring device is different from the visual evaluation. Figure 19 is estimation error 1/3 within rank (e.g. Evaluation A ^- Evaluation B ⁺ for) shows the percentage of FIG. 20 Evaluation error within one rank (for example, evaluation of the evaluation A B)
Shows the ratio of In both figures, (a) is 2
%, When evaluated only with the beam size for the relative luminance level of 50%, (b) when evaluated only with the beam size for the relative luminance level of 50%, and (c), the vertical luminance G and the beam size BS according to the present embodiment. It is a case where the shape of the beam profile is ranked and evaluated by
The hatched bar graphs are on a green display screen, the stippled bar graphs are on a red display screen, and the white bar graphs are those obtained by integrating them.

As is apparent from both figures, according to the method of ranking and evaluating the shape of the beam profile based on the vertical luminance G and the beam size BS according to the present embodiment, only the beam size of the conventional beam profile is used. It can be seen that the evaluation error can be significantly reduced as compared with the focus performance evaluation. In particular, in order to evaluate the focus performance with high accuracy within an evaluation error of 1/3 rank, it is extremely effective to finely rank the shape of the beam profile of the present application with the vertical luminance G and the beam size BS.

In the above-described embodiment, the shape of the beam profile is classified into a halo system and a blooming system based on the vertical center of gravity G, and each system calculates the rank value RG in five stages. In the vertical center of gravity G, it is determined only whether the shape of the beam profile is a halo type or a blooming type, and the rank value RS of each system is calculated by the beam size BS according to the determination result, and only the rank value RS is used. Focus performance evaluation may be performed. This method has a lower accuracy of the focus performance evaluation than the above-described method, but has an advantage that the calculation of the evaluation value can be reduced because the calculation of the rank value RG based on the vertical gravity center G is not required.

In the above embodiment, the vertical center of gravity G
Is used to determine whether the shape of the beam profile is a halo type or a blooming type. However, as shown in FIG. 2, the shape of the halo type beam profile and the shape of the blooming type beam profile are different from each other at the peak. The ratio R (= R1 / R1) between the beam diameter R1 and the beam diameter R2 of the foot portion.
R2, hereinafter, this ratio is called a beam size ratio. ) Is obviously different, the beam size ratio may be used to determine whether the profile shape is a halo type or a blooming type.

FIG. 22 shows the relationship between the focus performance evaluation by visual observation and the beam size ratio R of the beam profile. As shown in FIG. As the halo tendency increases, the beam size ratio R decreases relatively linearly. As the blooming tendency increases, the beam size ratio R decreases.
Is relatively linearly larger.

Therefore, the beam size ratio R is also shown in Table 1.
In the same manner as in the above, the light beam is classified into a halo system and a blooming system according to the range of the beam size R.
The rank values of the stages can be set, and the shape of the beam profile can be classified into the halo system and the blooming system using the rank values, and the rank values of a plurality of stages can be set in each system.

When the profile shape is classified into a halo system and a blooming system using the beam size ratio R, and a rank value is set in each system, the processing of steps # 3 to # 7 in the flowchart shown in FIG. Is replaced with the determination of the shape of the beam profile and the determination of the rank value using the beam size ratio R, the same focus performance evaluation can be obtained by the above-described procedure. In this method, since it is only necessary to calculate the beam sizes BSh, BSb and the beam size ratio R (= BSb / BSh) of the beam profile, the calculation is simplified as compared with the above-described embodiment method, and the evaluation calculation is reduced. can do.

In the above-described embodiment, the beam size BS of the beam profile is 2% relative luminance level and 50% relative luminance level.
Beam diameter B using the relative luminance level shown in FIG. 2 as a parameter
An appropriate relative luminance level is set based on a diagram showing the relationship between S and the focus performance evaluation by visual observation, and the present invention is not limited to these relative luminance levels.
That is, as shown in FIG. 22, when the shape of the beam profile is a halo tendency, the change in the beam diameter BS is large at a relative luminance level of 5% or less, and when the shape of the beam profile is a blooming tendency, the relative change is 10% or more. Since the change in the beam diameter BS increases with the luminance level, a beam diameter BS having an appropriate luminance level of 5% or less can be used in determining the rank value based on the beam diameter BS in the halo system, and the beam diameter BS in the blooming system. In the determination of the rank value, a beam diameter BS having an appropriate luminance level of 10% or more can be used.

The above embodiment takes advantage of the fact that the beam profile at a specific relative luminance level is significantly different from the vertical center of gravity depending on whether the beam profile has a halo tendency or a blooming tendency. Although the ranking is performed in a plurality of stages, the shape of the beam profile may be ranked in a plurality of stages by approximating the shape of the beam profile itself with a predetermined function.

FIG. 23 is a diagram showing a curve obtained when the order N of the function f (r) shown in the following equation (1) is changed.

In FIG. 23, the curve shown by the three-dot chain line from the curve shown by the solid line is obtained by sequentially increasing N.
In the equation (1), if r = 1, f (r) = e ^-1 =
0.368, and the level of 36.8% is constant regardless of the order N. That is, the width ro at the relative level of 38.6% is constant regardless of the order N.

[0118]

(Equation 9)

On the other hand, five beam profiles actually measured in each state from the halo tendency to the blooming tendency are expressed as follows:
When the processing is performed so that the beam size at 38.6% becomes the same, the curve shown in FIG. 24 is obtained. Note that FIG.
Indicates a curved portion on one of the left and right sides with respect to the peak position. In the figure, the curve shown by a solid line is a beam profile having a strong halo tendency, and the curve shown by a three-dot chain line is a beam profile having a strong blooming tendency.

When comparing the curve shown in FIG. 23 with the curve shown in FIG. 24, the two curves are very similar in characteristics, and the shape of one of the right and left sides with respect to the peak position of the actually measured beam profile is indicated by ( It can be approximated by equation (1). That is, the relative luminance level constituting the actually measured beam profile is processed so that the relative luminance level of 36.8% becomes 1, and the relative luminance level after the processing is changed by changing the order N of Expression (1). It is possible to calculate a curve f (r) that approximates a curve on one of the left and right sides with respect to the peak position of the beam profile composed of.

The approximate curve f increases as the halo tendency increases.
Since the order N of (r) decreases and the order N of the approximate curve f (r) increases as the blooming tendency increases, the shape of the beam profile can be classified according to the order N of the approximate curve f (r). By preparing an evaluation table in which visual evaluation is associated with the order N of the approximate curve f (r), the order N of the approximate curve f (r) is calculated, and the calculation result and the evaluation table are used. Focus performance evaluation having high correlation with visual evaluation can be obtained.

FIG. 25 shows the order N of the approximate curve f (r) calculated for the beam profiles at the respective visual evaluation levels A to D having the halo tendency to the blooming tendency. As shown in FIG. It can be seen from the order N of r) that it is possible to determine which evaluation value the shape of the beam profile has in the halo tendency or the blooming tendency. In FIG. 25, the degree of change in the order N in the halo tendency is gradual and it is difficult to identify the evaluation value as compared to the case of the blooming tendency. As described above, if the characteristics are close to a straight line having a relatively large inclination in the entire region, it is possible to determine the shape of the beam profile based on the order N of the approximate curve f (r) without any problem.

The method using the approximation curve f (r) has the advantage that the shape of the beam profile itself is directly identified, so that the shape can be accurately determined.

In the above embodiment, focus performance evaluation is performed by determining the overall shape of the beam profile. However, the right and left shapes of the beam profile at or near the peak position are separately determined. And the focus performance may be evaluated. In this way, even when the shape of the beam profile is not bilaterally symmetric, it is possible to perform focus performance evaluation having high correlation with visual evaluation.

In the above embodiment, the data acquisition control unit 2 of the focus performance measuring apparatus 1 calculates the beam profile and determines the shape of the beam profile based on the calculation result to evaluate the focus performance. However, the data capture control unit 2 may capture only the image data of the test pattern, and the control unit 51 of the measurement control unit 5 may calculate the beam profile and evaluate the focus performance.

[0126]

As described above, according to the present invention,
In a focus performance measuring device that captures a predetermined test pattern displayed on a CRT by an imaging unit and evaluates a focus performance of the CRT using the captured image, an energy intensity distribution of an electron beam of the CRT is calculated.
Since the shape of the energy intensity distribution is identified and the focus performance of the CRT is determined based on the identification result, the correlation between the measurement result of the focus performance and the visual evaluation is improved, and the focus performance with high measurement accuracy is improved. A measuring device can be realized.

In particular, since an approximation function indicating the shape of the energy intensity distribution is calculated and the focus performance is determined based on the shape determined by the approximation function, the shape can be accurately identified, and the measurement result and visual evaluation Can be further improved.

Also, the beam diameter at two intensity levels having different energy intensity distribution levels is calculated, and the focus performance is determined based on the calculation result and the shape of the energy intensity distribution. The shape of the distribution can be finely identified, and the correlation between the measurement result and the visual evaluation can be further improved.

Further, since the shape on the right side and the shape on the left side with respect to the peak position or near the peak position of the energy intensity distribution are distinguished to determine the focus performance, the shape of the energy intensity distribution is symmetrical. If not, it is possible to obtain a measurement result of the focus performance having a high correlation with the visual evaluation.

[Brief description of the drawings]

FIG. 1 is a diagram showing a definition of a vertical center of gravity of a profile.

FIG. 2 is a diagram showing a relationship between a profile shape of an electron beam and a focus state. .

FIG. 3 is a block diagram of a measurement system of the focus performance measuring device.

FIG. 4 is a block diagram of a data acquisition control unit of the focus performance measuring device.

FIG. 5 is a perspective view of an embodiment showing a basic configuration of an optical system of a CCD camera using a CCD line sensor.

FIG. 6 is a diagram for explaining an apparently enlarged imaging range of a CCD line sensor.

FIG. 7 is an essential part perspective view showing the structure of a face plate of an aperture grill type CRT.

FIG. 8 is a diagram for explaining a profile measurement method.

FIG. 9 is a diagram showing a relationship between a focus performance evaluation and a vertical center of gravity of a profile.

FIG. 10 is a diagram showing an example of ranking of the beam profiles in Tables 1 and 2 according to the vertical center of gravity and the beam diameter.

FIG. 11 is a diagram showing beam diameters at relative luminance levels of 2% and 50% of a profile.

FIG. 12 is a diagram for explaining a method of calculating a beam diameter at a desired relative luminance level from profile data.

FIG. 13 is a flowchart showing a procedure for evaluating focus performance.

FIG. 14 is a flowchart illustrating a processing procedure of profile measurement.

15A and 15B are diagrams for explaining an electron beam profile measurement process, and FIG. 15A is a diagram illustrating a state in which a test pattern is displayed discretely at a predetermined interval of a plurality of electron beams;
(B) is a diagram showing the relative luminance level of the light-emitting phosphor detected for each beam.

FIG. 16 is a diagram illustrating an example of a measurement result of a beam profile.

17A and 17B are diagrams showing an example of examining the correlation between the measurement device evaluation and the visual evaluation on the red display screen. FIG. 17A is a diagram in the case where evaluation is performed only with the beam size for a relative luminance level of 2%, and FIG. ) Is a diagram when only the beam size for the relative luminance level of 50% is evaluated, and (c) is a diagram when the shapes are ranked and evaluated based on the vertical gravity center G and the beam size BS according to the present embodiment. .

18A and 18B are diagrams showing an example of examining the correlation between the measurement device evaluation and the visual evaluation on the green display screen, and FIG. 18A is a diagram in the case where evaluation is performed only with the beam size for a relative luminance level of 2%, and FIG. ) Is a diagram when only the beam size for the relative luminance level of 50% is evaluated, and (c) is a diagram when the shapes are ranked and evaluated based on the vertical gravity center G and the beam size BS according to the present embodiment. .

FIG. 19 is a diagram showing an example in which a rate at which the evaluation by the focus performance measuring device is different from a visual evaluation within an evaluation error of 1/3 rank is shown.

FIG. 20 is a diagram illustrating an example in which a rate at which the evaluation by the focus performance measuring device differs from the visual evaluation within one rank of the evaluation error is examined.

FIG. 21 is a diagram showing a relationship between focus performance evaluation and a beam size ratio of a profile.

FIG. 22 is a diagram illustrating a relationship between a beam diameter using a relative luminance level as a parameter and focus performance evaluation by visual observation.

FIG. 23 is a diagram showing a curve obtained when the order N of the function f (r) shown in the equation (1) is changed.

FIG. 24 shows the measured 5 beam profiles in each state from the halo tendency to the blooming tendency as 38.6.
It is a figure which shows the curve obtained by processing so that the beam size in% may become the same.

FIG. 25 is an approximate curve f (r) for a beam profile at each visual evaluation level from a halo tendency to a blooming tendency.
FIG.

FIG. 26 is a diagram illustrating characteristics of an order N obtained by performing logarithmic processing twice on the order N of the approximate curve f (r) illustrated in FIG. 25;

[Explanation of symbols]

REFERENCE SIGNS LIST 1 focus performance measuring device 2 data acquisition control unit (pattern display unit) 21 A / D converter 22 VRAM 23 ROM 24 RAM 25 control unit (approximate expression calculation unit) 251 profile calculation unit (intensity distribution calculation unit) 252 center of gravity calculation Unit 253 shape determination unit 254 size determination unit (beam diameter calculation unit, beam diameter ratio calculation unit) 255 focus performance evaluation unit (determination unit) 26 synchronization signal delay unit 27 horizontal / vertical synchronization signal detection unit 28 communication unit 3 CCD camera ( 4) Signal generator 5 Measurement control unit 51 Control unit 52 Display unit 53 Keyboard 6 Color CRT 61 Color cathode ray tube 62 First drive control circuit 63 Second drive control circuit 7 Photographing lens 8 Half mirror 9A, 9B, CCD line sensor 10A, 10B cylindrical lens

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Sadazo Takase 10 Sanjo Kotatsumi, Onishi-shi, Aichi Prefecture Soharegonal 202 F-term (reference) 5C061 BB03 CC05 EE13

Claims (6)

[Claims] 1. A pattern display means for displaying a predetermined test pattern on a CRT for focus performance measurement, an image pickup means arranged to face a display surface of the CRT and picking up the test pattern, and an image picked up by the image pickup means. An intensity distribution calculator for calculating the energy intensity distribution of the electron beam of the CRT using the image of the test pattern, and a determiner for determining the focus performance of the CRT based on the shape of the energy intensity distribution. A focus performance measuring device for a CRT. 2. The method according to claim 1, wherein the determining means includes a first beam diameter at a predetermined first intensity level of the energy intensity distribution and a predetermined second intensity higher than the first intensity level.
Beam diameter ratio calculating means for calculating a ratio with the second beam diameter at the intensity level of the CRT based on the shape of the energy intensity distribution determined by the beam diameter ratio calculated by the beam diameter ratio calculating means. 2. The focus performance measuring device for a CRT according to claim 1, wherein the focus performance is determined. 3. The method according to claim 1, wherein the determining unit includes a center of gravity calculating unit that calculates a center of gravity of the energy intensity distribution in a vertical direction, based on a shape of the energy intensity distribution determined by the center of gravity calculated by the center of gravity calculating unit. 2. The CRT according to claim 1, wherein the focus performance of the CRT is determined.
Focus performance measuring device. 4. The focus performance of the CRT based on the shape of the energy intensity distribution determined by the approximation function, wherein the determination means approximates the shape of the energy intensity distribution by a function represented by the following equation (1). 2. The focus performance measuring device for a CRT according to claim 1, wherein: (Equation 1) 5. The CRT according to claim 1, wherein the determination unit determines the focus performance of the CRT based on a shape on at least one of a left side and a right side of a peak position or a vicinity of the peak position of the energy intensity distribution. Items 1-4
The focus performance measuring device for a CRT according to any one of the above. 6. A method according to claim 1, wherein said determining means includes a first beam diameter at a predetermined first intensity level of said energy intensity distribution and a second predetermined beam intensity higher than said first intensity level.
Further comprising a beam diameter calculating means for calculating a second beam diameter at an intensity level of the CRT based on the shape of the energy intensity distribution and the first and second beam diameters.
2. The focus performance of the camera is determined.
6. The focus performance measuring device for a CRT according to any one of claims 1 to 5.