JP3493402B2 - Electron beam shape measurement device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring a beam shape of an electron beam applied to a display surface of a CRT, and more particularly to a device for forming a display surface of a CRT. The present invention relates to a device in which light emission efficiency (luminance unevenness) of a light body is considered. 2. Description of the Related Art In recent years, CRTs are used for information processing,
It is applied to various devices such as measuring instruments, and its image quality largely depends on the beam shape of the electron beam. For this reason, at the stage of designing or manufacturing a CRT, the shape of an electron beam is observed and inspected. CRT
Is coated with a phosphor on its display surface, and a shadow mask of a predetermined shape is interposed between the electron gun and the phosphor to shield the electron beam, and the electron beam from the gap between the shadow mask is (relatively). Irradiation is performed on the phosphor portion of the CRT display surface (which can be regarded as being arranged), and the portion emits light. [0003] As this type of measuring device, a type in which an electron beam is shaken (moved) is conventionally known. As a type of moving an electron beam, U.S. Pat.
Japanese Patent Application Laid-Open No. 6-1629 discloses a method in which measurement is performed using one phosphor as disclosed in Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent Publication No. 33, there has been proposed an apparatus in which the measurement time is shortened by using a plurality of phosphors. [0004] The measuring devices described in the above two publications each measure the emission luminance of a phosphor obtained through a shadow mask by moving an electron beam and measure the luminance. The beam shape is measured based on the data.However, the phosphor has a variation in luminous efficiency due to the difference in coating thickness and the like, and the brightness differs even when irradiated with an electron beam of equal intensity. In the shape measurement based only on the luminance data of the phosphor as described above, there is a limit in the measurement accuracy. In a test on a commercially available CRT, a result was obtained in which a variation of about 20% was present. The degree of this variation is a suitable beam shape (5% or 50% of the beam intensity).
It is considered that this becomes a large error factor when calculating the beam cross-sectional diameter at the% level. [0005] The present invention has been made in view of the above,
It is an object of the present invention to provide an electron beam shape measuring device capable of correcting uneven brightness of phosphors arranged on a CRT display surface to more accurately measure the shape of an electron beam. According to the present invention, there is provided a CRT for sweeping a display surface by a deflection signal and displaying a required image by irradiating an electron beam during the sweep.
An electron beam shape measuring device arranged on the CRT display surface and measuring the shape of an electron beam based on measurement data of light emission luminance from a phosphor that emits light by irradiation with the electron beam. Optical detection means for detecting the light emission luminance of the phosphor at a number of detection positions, and a phosphor contained within a detection range of a CRT display surface on which the optical detection means is arranged to face the surface. Beam irradiation control means for sweeping and irradiating an electron beam having the same intensity, a movement control means for forming a sweep line by moving the electron beam on the CRT display surface in a direction of arrangement of the phosphors by a predetermined pitch, and detects the light emission brightness of the phosphor in the detection range irradiation control means actuates while moving little by little pitch so as to cover the valley of the beam position vertically above the sweep line And a correction coefficient generating means for obtaining a correction coefficient for correcting the luminance unevenness at the plurality of detection positions of the phosphor from the obtained light emission luminance data, and operating the movement control means and setting the correction coefficient within the detection range for each pitch movement. And a calibration constant generating means for detecting a calibration constant between the beam movement control amount and the beam movement distance from the obtained emission luminance data, and moving the movement control means using the calibration constant. Measuring means for operating to move by a distance and detecting the emission luminance of the phosphor within the detection range for each movement, and correcting the obtained emission luminance data with the correction coefficient to generate the measurement data. It is provided. According to the present invention, the beam irradiation control means is operated while moving the beam position vertically at a small pitch so as to cover the valley of the sweep line, and the electron beam is moved at a predetermined pitch. Each time a sweep line is formed , the emission luminance of the phosphor within the detection range is detected, and a correction coefficient for correcting the luminance unevenness at the above-described many detection positions of the phosphor is obtained from the obtained emission luminance data ( First calibration). Next, the movement control means is operated, and at each pitch movement, the emission luminance of the phosphor within the detection range is detected, and a calibration constant between the beam movement control amount and the beam movement distance is obtained from the obtained emission luminance data. (Second calibration). At the time of measurement, the movement control means is calibrated with the calibration constant, thereby ensuring accurate movement by the beam movement distance, and detecting the emission luminance of the phosphor within the detection range for each movement. . Since the obtained light emission luminance data is subjected to luminance unevenness correction using the correction coefficient, accurate light emission luminance data, that is, measurement data is generated. The obtained measurement data is displayed in a required manner, for example, three-dimensionally. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of an electron beam shape measuring apparatus according to the present invention will be described with reference to FIGS. FIG. 1 is a circuit block diagram of a main body of the apparatus, and FIG. 2 is an overall configuration diagram of the apparatus. In FIG. 2, 1 is a main body, 2 is a personal computer (hereinafter referred to as a personal computer), 3 is a signal generator, 4 is a CCD camera, and 5 is a cathode ray tube (hereinafter referred to as a CRT) to be measured. Each is connected to the main body 1 via a cable 6. The main unit 1 takes in the image pickup signal of the CCD camera 4 and performs various processes required for measuring the electron beam shape. The personal computer 2 controls the operation of the entire measuring apparatus, has a keyboard 21 for operating instructions, and has a display unit 2 for displaying measurement results as necessary.
2 is provided. The signal generator 3 generates a horizontal synchronizing signal and a vertical synchronizing signal as deflection signals to cause the CRT 5 to deflect an electron beam, and also generates a predetermined pattern for measurement. CCD camera 4 is CRT5
A large number of CCs are used to detect the emission brightness when the phosphors arranged on the display surface
The D elements are arranged in a matrix. C
The CD camera 4 has an imaging lens disposed in front of a light receiving surface, and outputs optical magnification data together with emission luminance data. The optical magnification data may be stored in a writable internal memory of the personal computer 2 in advance, and may be read out to the main unit 1 as needed. The CRT 5 as a measuring object used in the present embodiment is an aperture grill type in which the arrangement of phosphors on the display surface is a so-called vertical stripe pattern, but the present invention is not limited to this type. . Also, CRT
Is not particularly limited. In FIG. 1, reference numeral 11 denotes an A / D converter for A / D converting an image signal from the CCD camera 4, and converts an image signal from the CCD camera 4 in a level direction, for example, to a 10-bit digital value. . Reference numeral 12 denotes a measurement data storage unit that takes in the A / D converted image signal. The CCD camera 4 according to the present embodiment has CCD elements of 768 pixels (11.6 μm per pixel) in the horizontal direction and 484 pixels (13.6 μm per pixel) in the vertical direction arranged in a matrix. Therefore, the measurement data storage unit 1
Reference numeral 2 denotes 768 × 484 data, each of which has at least a capacity capable of storing 10-bit data, and is taken in at an address corresponding to the arrangement position of the CCD elements. Reference numeral 13 denotes a microcomputer (hereinafter referred to as a microcomputer) which controls the operation of each circuit in the main body 1 and controls necessary data communication and timing between the personal computer 2, the signal generator 3 and the CCD camera 4. , A microcomputer). Numeral 14 denotes a vertical synchronizing signal detector for detecting a vertical synchronizing signal from the signal generator 3, and numeral 15 intervenes between the signal generator 3 and the vertical synchronizing signal detector 14, and outputs a horizontal synchronizing signal and a vertical synchronizing signal, respectively. This is a synchronization signal delay unit for individually delaying. The delay amount of each synchronization signal is
It is set by the control signal from. The microcomputer 13
Communicates with the signal generator 3 via the communication unit 16 and
Instruct generation of a required pattern on the RT display surface. The main body 1 guides a predetermined pattern signal from the signal generator 3 to the electron gun of the CRT 5 and guides horizontal and vertical synchronizing signals to a deflection coil section (both not shown). The optical magnification detecting section 17 reads the optical magnification data from the CCD camera 4 or the data when the data relating to the optical magnification is stored in the personal computer 2 and guides it to the microcomputer 13. The optical magnification data is used when calculating the distance between phosphors as described later. The shape measurement of the electron beam in the present invention is performed by
This is performed after performing the first calibration and the second calibration. The first calibration is for correcting the variation of the luminous efficiency (luminance unevenness) of the phosphor, and the second calibration is for associating the movement time (phase (movement control amount)) of the synchronization signal with the movement distance of the electron beam. is there. First, a description will be given, with reference to FIGS. Figure 3 shows a CCD
4A shows an electron beam intensity during horizontal sweep, and FIG. 4B shows a captured image of the CCD camera 4 in a state where the CRT 5 is fully lit in a single color. FIG. 5A shows the luminance centroid of the image shown in FIG.
(B) shows the emission luminance of the phosphor in the horizontal direction. FIG. 6 is a flowchart showing the first calibration operation. First, the CRT 5 is turned on in a single color (#)
2). Monochromatic full lighting refers to irradiating a beam of a constant level from the electron tube over the entire area of the CRT display surface, but may be limited to a required area (detection range) specially prepared for measurement. Good. In this state, or when the CRT 5 is turned on in a single color, the CCD camera 4 is set in advance so that the CCD camera 4 faces the area in which the single color is turned on.
It is held in contact with the display surface of T5. The contact holding may be performed by a measurer, or a holding jig may be used. And
When the CCD camera 4 is operated, light from the emitting phosphor is received by the CCD elements on the imaging surface 41, and the received light data from each CCD element is subjected to A / D conversion. Captured (# 4). In the first measurement, since the immediately preceding value has been reset to 0, the first received light data is taken in (as a maximum value) (# 6). The received light data will be described with reference to FIG. In the drawing, seven aperture grill type phosphors 51 are vertically separated from each other by a predetermined width and a predetermined distance in the imaging surface 41 of the CCD camera 4. In the figure, the black part indicates the position of the horizontal sweep line (four lines are visible), the diagonal part indicates the valley of the sweep line, and the white part indicates the area that does not emit light because a phosphor of another color is applied. Is shown. As shown in FIG. 4A, the electron beam during the horizontal sweep has a high intensity at the center of the beam, and it can be seen that the above-mentioned valley is generated between the adjacent horizontal line beams. Therefore, the brightness is high in the black portion, and the brightness is low in the valleys of the sweep lines, which are the hatched portions.
As described above, when the electron beam intensity differs depending on the position on the surface of the phosphor 51, the uneven brightness of the phosphor 51 itself cannot be known. Then, the electron beam is vertically moved (# 8). The vertical movement of the electron beam is performed by sequentially delaying the vertical synchronizing signal by the synchronizing signal delay unit 14 at a pitch that can be regarded as equal in intensity, for example, 2 μsec.
This delay operation is repeated, for example, only 15 times so as to cover the above-mentioned valley, that is, the horizontal sweep line. Until the vertical movement of the electron beam is repeated a predetermined number of times (NO in # 10), the measurement for each vertical minute movement and the maximum value hold processing of the measurement data are executed (# 4 to # 4).
# 10 loop). The microcomputer 13 compares the magnitude of the immediately preceding measurement data, that is, the measurement data stored in the measurement data storage unit 12, with the light reception data received this time by the CCD element at the corresponding position. The data is updated and taken into the measurement data storage unit 12. This maximum value hold processing is performed on the received light data of all the CCD elements for each minute vertical movement. As a result, when the vertical movement of the electron beam is completed, the phosphor surface is irradiated with the electron beam at the same intensity level.
The variation in the maximum light receiving data in the CD element can be grasped as a difference (luminance unevenness) in the luminous efficiency of the phosphor 51 itself. When the vertical movement of the electron beam is completed (# 1)
Then, the center of gravity of the luminance is calculated using the received light data taken into the measurement data storage unit 12 (# 1).
2). The luminance centroid is calculated as coordinates (X, Y). To calculate the luminance centroid coordinates, a preset threshold value or, for example, 30% of the peak value in the acquired measurement data is used.
The above measured data is used to exclude data with a level difference that is more than necessary. Now, each storage address of the measurement data storage unit 12 (corresponding to each CCD element)
Assuming that x is x and the measured data at this address is L (x), the X coordinate of the luminance centroid = Σx · L (x) / ΣL (x). On the other hand, the Y coordinate of the luminance centroid has a constant pitch Δy,
For example, it is set to 40 μm. Therefore, as shown in FIG. 5A, the coordinates of the luminance center of gravity (X, Y) are at positions indicated by + signs in the figure, and there are 49, for example. Next, in this embodiment, in order to improve the value of each luminance barycentric coordinate (X, Y) itself or accuracy, in this embodiment, a total of 25 pixels for 5 × 5 pixels centered at each luminance centroid coordinate (X, Y). number of measurement summation of data _{sum 1 (1) ~Sum 1 (} 49) is calculated (# 14). And each sum Sum ₁ (1)
The correction coefficient is calculated so that ~ Sum ₁ (49) has the same value. For example, with reference to the sum Sum ₁ (1), the uneven brightness correction coefficient for each sum Sum ₁ (N) is obtained as Kei (N) = Sum ₁ (1) / Sum ₁ (N). Here, N is an integer of 1 to 49. Next, the correspondence between the movement time (phase (movement control amount)) of the synchronization signal and the movement distance of the electron beam, which is the second calibration operation, will be described with reference to FIGS. 7A shows an image captured by the CCD camera 4 in a state where the dots D1 and D2 are displayed on the CRT 5, and FIG. 7B shows the light emission luminance of the phosphor in the horizontal direction. FIG.
FIG. 4 is a diagram for explaining the relationship between the horizontal movement distance and the movement time of a dot, together with the emission luminance. FIG. 9 is a flowchart showing the second calibration operation. Since the CRT 5 used in this embodiment is of the aperture grill type, it is sufficient to consider only the horizontal moving time, which is the direction in which the phosphors are arranged, and the moving distance of the electron beam. In the type of CRT, using the same method as in the horizontal direction,
It is necessary to calibrate the moving time and the moving distance of the electron beam also in the vertical direction. The calibration constant α between the moving time and the moving distance is represented by α = L / T. Here, L is the distance between the phosphors obtained as described later, and T is the horizontal movement time (time between dots D1 and D2) corresponding to the distance L. First, the dots D1 and D2 are displayed on the CRT 5 by the signal generator 3 (# 20). Note that CC
It is assumed that the D camera 4 is kept observable at the same location on the CRT 5 following the first calibration work. The display of the dots D1 and D2 may be controllable so that they can be displayed on the left and right in accordance with the detection range of the CCD camera 4, or the dot display position is specified in advance, and the CCD camera is adjusted in accordance with the position. 4 may be arranged from the time of the first calibration work. In this state, the CCD camera 4 is operated,
Light from the phosphor portion that emits light by being irradiated with the electron beam is received by the CCD element on the imaging surface 41. The light receiving data from each CCD element is A / D converted and then taken into the measurement data storage unit 12 (# 22). Next, using the measurement data corresponding to the left half of the imaging surface 41, the dot D1
Find out. That is, the total sum ₂₁ of the measurement data of 5 × 5 pixels centered on each luminance center coordinate (X, Y) obtained in the first calibration work, and the total sum ₂₁ belonging to the left half is obtained. The phosphor 51 having the largest total value from among them
(Shown by an O mark in FIG. 7A) is specified (# 2
4). That is, the shape of the electron beam intensity on the left side is shown in FIG.
As shown in FIG. 2B, the phosphor has a mountain shape, and the light emission luminance of the phosphor near the top is maximized. Then, the sum Sum ₂₁ included in the phosphors 51 indicated by the O mark is summed up, and among the luminance centroids, a luminance threshold having a predetermined threshold value or a total value of 50% or more of the peak total value in consideration of accuracy. The X-coordinate is totaled, and the average value is further divided by the number of luminance centroids to calculate the average centroid coordinate Ave1 (# 26). Similarly, the dot D2 is examined by using the measurement data corresponding to the right half of the imaging surface 41. That is, the first
Of the measurement data for 5 × 5 pixels centered on each luminance center coordinate (X, Y) obtained by the calibration operation of the above, and each sum Sum ₂₂ belonging to the right half part is obtained. (Indicated by Δ in FIG. 7A)
Is specified (# 28). That is, the shape of the electron beam intensity on the right side has a mountain shape as shown in FIG. 7B, and the light emission luminance of the phosphor closer to the top is maximized. Then, the sum Sum ₂₂ included in the phosphors 51 indicated by the Δ mark is summed, and among the luminance centroids, a luminance threshold having a predetermined threshold value or a total value of 50% or more of the peak total value in consideration of accuracy. The X coordinate is totaled, and the total value is further divided by the number of luminance centroids to calculate the average luminance centroid Ave2 (# 30). Subsequently, in step # 32, the electron beam is horizontally moved. The horizontal movement of the electron beam is performed by synchronizing the horizontal synchronizing signal with a fine pitch,
This is performed by sequentially delaying (transfer amount control) by nsec (nanosecond). The number of times of this delay operation will be described later. Until the horizontal movement of the electron beam is repeated a predetermined number of times (NO in # 40), the measurement for each horizontal minute movement and the sum of the luminance centroids Sum ₂₁ and Sum on each of the left and right sides are performed.
₂₂ are executed (loop of # 32 to # 40). In other words, in steps # 36 and # 38, each sum Sum ₂₁ included in the O-marked phosphor is obtained every horizontal minute movement.
Is calculated, and the sum of the respective sums Sum ₂₂ included in the phosphors indicated by Δ is calculated. Next, it is determined whether or not the horizontal movement of the predetermined electron beam has been completed (# 40). If not completed, the process returns to step # 32, and if completed, the process proceeds to step # 42. In step # 42, the above-mentioned distance L (μm) between the phosphors is obtained as L = 11.6 × (Ave2−Ave1) / optical magnification using the average luminance centroids Ave1 and Ave2. Subsequently, the moving time T corresponding to the distance L
Is calculated (# 44). Here, the calculation of the movement time T will be described with reference to FIG. B1 and B2 indicated by solid lines indicate left and right electron beams before horizontal movement, and B1 'and B2' indicated by broken lines indicate left and right electron beams at the end of horizontal movement. For the dot D1 on the left side, the sum of the respective sums Sum ₂₁ included in the phosphor indicated by the O mark before the horizontal movement is equal to the sum of the respective sums Sum ₂₁ included in the phosphor each time the phosphor is sequentially horizontally moved. Is determined, and it is determined whether or not the calculated total value has decreased to a preset electron beam movement end level, and the time when the level has decreased to this level is defined as T1. [0037] With respect to the right of the dot D2, the total of the sum Sum ₂₂ contained in the phosphor of the Δ mark before the horizontal movement, the sum of the sum Sum ₂₂ contained in the phosphor for each sequentially moved horizontally Is determined, and it is determined whether or not the obtained total value has decreased to the electron beam movement end level, and the time when the total value has decreased to this level is defined as T2. Accordingly, the step # 40 ends when the horizontal movement of the electron beam is confirmed that both of the above-mentioned respective sums have fallen to the preset electron beam movement end level. The electron beam movement end level is set to a fixed value, for example, about 50% of the total value that can be obtained before the horizontal movement. The time TT indicates the time between the two dots D1 and D2 displayed by the signal generator 3, and
Obtained by calculation. That is, CRT5 is VGA
It is displayed in (video graphic array) mode (dot clock = 25.175 MHz). If the interval is 8 dots, TT = 8 / 25.175 (μsec). Therefore, the above-mentioned movement time T is obtained as T = TT + T1-T2. As a result, the aforementioned calibration constant α (= L
/ T) is calculated. Next, FIGS. 10 to 12 are for explaining the profile measurement of the electron beam, and the profile measurement of the electron beam is performed following the first and second calibration operations. FIG. 10 shows received light data by the CCD camera 4 at the time of electron beam profile measurement. FIG. 11 is a flowchart showing the operation of electron beam profile measurement. FIG. It is a three-dimensional view showing an example of a beam profile display. First, one dot D0 is displayed on the CRT 5 by the signal generator 3 (# 60). Note that CC
After the first and second calibration work, the D camera 4
Are kept observable. The dot D0 is controlled so as to be displayed preferably at substantially the center of the detection range of the CCD camera 4, or at least at a position where no chip is generated even by a horizontal movement described later. In this state, the CCD camera 4 is operated,
Light from the phosphor portion that is illuminated with the electron beam and emitted is received by the CCD elements on the imaging surface 41. The received light data from each CCD element is A / D converted and then stored in the measurement data storage unit 12. Captured (# 62). Next, the dot D0 is checked from the measurement data. That is, 5 × 5 around each luminance center coordinate (X, Y) obtained in the first calibration work.
The sum Sum ₃ of the measurement data for the pixels is calculated (# 6)
4) Further, each total value is corrected by multiplying by a luminance unevenness correction coefficient obtained in the first calibration work (#)
66). After the correction of the uneven brightness, the horizontal synchronizing signal is sequentially delayed by the synchronizing signal delay section 15, and the electron beam is moved in the horizontal direction by a predetermined minute pitch (# 68). At each horizontal minute movement, the delay amount of the horizontal synchronizing signal, that is, the moving distance corresponding to the moving time is calibrated using the calibration constant α obtained in the second calibration work, whereby the accurate moving distance of the electron beam is obtained. Is calculated (# 70). Next, it is determined whether or not the electron beam has been moved by the distance L between the phosphors using the calibrated data of the moving distance (# 72). If it has not been moved, the processing of steps # 62 to # 72 is repeated, and if it has been moved, the electron beam profile calculation is started (# 74). The calculation of the profile of the electron beam is performed by using the total value obtained for each movement of the electron beam at a fine horizontal pitch, so that the electron beam can be accurately moved by the distance L between the phosphors. Accordingly, the entire area of the dot D0 of the electron beam can be secured by any one of the phosphors, and can be secured as a total value without being overlapped with other phosphors. In addition, the magnification is surely equal in the horizontal and vertical directions, and the display of the electron beam profile is not distorted. Then, by using the moving position of the electron beam, the position of 5 × 5 pixels centered on each luminance center coordinate (X, Y) obtained at each moving position, and the total value of the positions, The beam shape of the beam is calculated as the irradiation intensity. The calculation result is led to the personal computer 2, where it is subjected to required three-dimensional graphic processing and displayed on the display unit 22. FIG.
In 2, the bottom plane consists of horizontal and vertical sweep line directions,
The irradiation luminance is a vertical component. In this embodiment,
The measurement time from the first calibration to the display could be suppressed to about 2 seconds. Although the present embodiment has been described with reference to the aperture grill type CRT, the present invention is not limited to this CRT type, but is applicable to dot matrix type and stripe type CRTs. According to the present invention, a correction coefficient for correcting the luminance unevenness of the phosphor is obtained in advance, and at the time of measurement, the emission luminance of the phosphor is corrected using the correction coefficient, and the correction is performed. Since the subsequent data is configured to be treated as measurement data, the shape of the electron beam can be measured more accurately than a conventional measurement device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit block diagram of a main body of an electron beam shape measuring apparatus according to the present invention. FIG. 2 shows an overall configuration diagram of an electron beam shape measuring apparatus according to the present invention. FIG. 3 is a diagram illustrating an imaging surface of a CCD camera. 4A and 4B are diagrams for explaining brightness unevenness correction as a first calibration operation, wherein FIG. 4A shows an electron beam intensity during horizontal sweep,
(B) shows a captured image of the CCD camera in a state where the CRT is fully lit in a single color. 5A and 5B are diagrams for explaining luminance unevenness correction which is a first calibration operation. FIG. 5A illustrates a luminance centroid of the image shown in FIG.
(B) shows the emission luminance of the phosphor in the horizontal direction. FIG. 6 is a flowchart showing a first calibration operation. FIGS. 7A and 7B are diagrams for explaining the association between the movement time (phase (movement control amount)) of the synchronization signal and the movement distance of the electron beam, which is the second calibration operation, and FIG.
(B) shows the light emission luminance of the phosphor in the horizontal direction when the image captured by the CCD camera is displayed in a state in which and are displayed. FIG. 8 is a diagram for explaining a relationship between a horizontal movement distance and a movement time of a dot together with light emission luminance in a second calibration operation. FIG. 9 is a flowchart showing a second calibration operation. FIG. 10 shows C at the time of electron beam profile measurement.
It is a figure which shows the light reception data by a CD camera. FIG. 11 is a flowchart showing an operation of electron beam profile measurement. FIG. 12 is a three-dimensional view showing an example of a profile display of an electron beam. [Description of Signs] 1 Main body 2 Personal computer 3 Signal generator 4 CCD camera 5 CRT 6 Cable 11 A / D converter 12 Measurement data storage 13 Microcomputer 14 Vertical synchronization signal detector 15 Synchronization signal delay unit 16 Communication unit 17 Optical Magnification detecting unit 22 Display unit 41 Imaging surface 51 of CCD camera Phosphor D0 to D1 Dot B1, B2 Electron beam

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-223722 (JP, A) JP-A-6-162933 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01J 9/42-9/44 H04N 17/04

Claims (1)

(1) A CRT for sweeping a display surface by a deflection signal and displaying a required image by irradiating an electron beam during the sweep. An electron beam shape measuring device arranged on a display surface and measuring the shape of an electron beam based on measurement data of emission luminance from a phosphor that emits light by irradiation with the electron beam,
An optical detecting means for detecting the light emission luminance of the fluorescent substance at a number of detection positions, the optical detecting means being located opposite to the display surface of the RT; Beam irradiation control means for sweeping and irradiating the phosphor with an electron beam of the same intensity;
Movement control means for forming a sweep line by moving a predetermined pitch in the arrangement direction of the phosphors on the T display surface, and covering the beam irradiation control means so as to cover the valley of the sweep line vertically with respect to the beam position.
A correction coefficient for operating while moving by a small pitch at a time, detecting the emission luminance of the phosphor within the detection range, and correcting the luminance unevenness at the plurality of detection positions of the phosphor from the obtained emission luminance data. Operating the movement control means and detecting the light emission luminance of the phosphor within the detection range for each pitch movement, and obtaining a beam movement control amount and a beam movement distance from the obtained light emission luminance data. The calibration constant generation means for determining the calibration constant, and the movement control means are operated to move by the beam movement distance using the calibration constant, and the emission luminance of the phosphor within the detection range is detected for each movement. Measuring means for generating the measurement data by correcting the obtained emission luminance data with the correction coefficient. .