JPH05328412A - Measurement device for position of picture - Google Patents

Abstract

PURPOSE:To measure a position on a display screen within an outer frame at a high speed with high accuracy. CONSTITUTION:A display picture 4 in white raster is displayed on a tube screen of a CRT 3, an object is picked up by a camera 5a so that the picked-up image comes to a left side outer frame 2 and the object is picked up by a camera 5c so that the picked-up image comes to a rightside outer frame 2 and each output picture information is processed to calculate the position of the left side and the right side of the display picture 4. Moreover, a display picture 4 in black raster is displayed on a tube screen of the CRT 3, a strobo light 8a is used to light the object and it is picked up similarly by the camera 5a and a strobo light 8B is used to light the object and it is picked up similarly by the camera 5C and each output picture information is processed to calculate the position of a ridge line of the left side outer frame 2 and the position of a ridge line of the right side outer frame 2. Then the position of the display pattern 4 in the outer frame 2 in the horizontal direction is discriminated based on the interval between the left side position of the display picture 4 and the ridge line position of the left side outer frame 2 and the interval between the right side position of the display picture 4 and the ridge line position of the right side outer frame 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screen position measuring device for automatically measuring the screen position of an underscan character display device at high speed and with high accuracy.

[0002]

2. Description of the Related Art In an underscan character display device using a CRT (cathode ray tube), a rectangular screen is displayed on the CRT in an outer frame in front of the character display device. The screen must be set so that the positions of the four sides above, below, left and right of the raster edge are equidistant from the ridgeline where the CRT and the outer frame contact (hereinafter referred to as the ridgeline of the outer frame). It is required that the distance be zero as much as possible. Therefore, the character display device is provided with a screen position adjusting mechanism, which allows the position of the display screen to be adjusted in the vertical and horizontal directions.

Conventionally, in order to adjust the position of the display screen,
A method of automatically measuring the position of this display screen is known. Examples thereof are JP-A-1-133497 and JP-A-3.
It is disclosed in Japanese Patent Publication No. 99376.

In the former example, two ITs are provided on each of the upper, lower, left and right sides.
A V camera (hereinafter referred to as a camera) is arranged, and the upper and lower cameras are respectively above the projection area of the display screen and a part of the upper part of the outer frame on the tube surface of the CRT, and below the projection area of the display screen. And a part of the lower part of the outer frame is the imaging area, and the left and right cameras are the left part of the display area of the display screen, the upper part of the left part of the outer frame, and the right part of the display area of the display screen, respectively. A part of the right side portion of the outer frame is used as an imaging area, and each imaging area is imaged. Then, for each of these cameras, a raster is displayed on the entire tube surface in the outer frame to emit light, and in this state, the first mode for imaging the respective imaging regions and the display screen is projected on the tube surface. In this state, it is possible to set the second mode in which the respective imaging regions are imaged, the position of the ridge line of the outer frame is detected from the image information obtained by the imaging in the first mode, and the second mode is set. The position of the side of the display screen is detected from the image information obtained by capturing the image, and the position of the display screen within the outer frame is detected from these position information.

Further, in the latter example, a camera having an image pickup area as an area including an outer frame is provided in front of the CRT display device, and one illumination means for illuminating the entire image pickup area of the camera from the front side is provided. It is possible to set a first mode in which the display screen is projected and imaged on the tube surface of the CRT and a second mode in which the display screen is illuminated and illuminated by the illumination means without the display screen, and the first mode is set. The position of the ridgeline of the outer frame is detected from the image information obtained by the image pickup in step S1, and the position of the side of the display screen is detected from the image information obtained by the image pickup in the second mode. The position of the display screen within the frame is detected. As the illuminating means, a method of using a halogen lamp and illuminating with a circle spot has been standard.

[0006]

However, in the former case, even if a raster is displayed on the entire tube surface in the outer frame to emit light, the contrast between the outer frame and the tube surface is changed depending on the brightness and color of the outer frame. In some cases, the ridgeline of the outer frame is not clear, and in such a case, the ridgeline position of the outer frame cannot be accurately detected. Also, the measured C
The RT display device also requires special deflection means for raster-displaying the entire inside of the outer frame.

In the latter case, since the illuminating means illuminates from the front, the contrast between the outer frame and the tube surface may not be sufficient due to the brightness and color of the outer frame, and the ridgeline of the outer frame may be unclear. Further, there is a problem that it takes an irradiation time to turn the halogen lamp on and off, which becomes an obstacle and the measurement time becomes longer than 20 seconds.

An object of the present invention is to solve the above problem and provide a screen position measuring device capable of performing accurate measurement in a short time.

[0009]

In order to achieve the above object, the present invention provides an image of a display screen which is projected on the surface of a cathode ray tube including the ridge line of an outer frame which is a boundary with the tube surface. At least four image pickup means each having a left side portion, a right side portion, an upper side portion, and a lower side portion of the output area as image pickup areas, a plurality of strobe lights arranged obliquely in front of the tube surface, and each of the image pickup means. A first mode in which the strobe light is turned on to cause the image pickup means to perform an image pickup operation, and a second mode in which a uniform high-intensity raster display screen is displayed on the tube surface to cause the image pickup means to perform an image pickup operation
Of the output means of the image pickup means in the first mode and the output information of the image pickup means in the second mode are processed within the outer frame of the display screen. And processing means for creating the position information of.

[0010]

By the respective image pickup means, the upper and lower sides of the display screen displayed on the tube surface of the cathode ray tube, the four left and right sides and the upper and lower sides of the outer frame,
The position of the display screen is detected from the difference between the position of the side and the position of the ridge in the same direction by measuring the positions of the left and right four ridge lines. Since this image is displayed, the side of this side clearly appears in the output of the image pickup means, and it is possible to accurately detect the side position.When measuring the edge of the outer frame, the edge of the outer frame is illuminated by the strobe light. The ridge line portion clearly appears in the output of the image pickup means, and the accurate ridge line position can be detected. Further, since the strobe light capable of performing sufficient illumination at high speed ON / OFF is used as the illumination means, the image capturing means is sufficient to capture one screen, which enables high-speed measurement.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a screen position measuring device according to the present invention, in which 1 is a CRT display device, 2 is an outer frame,
3 is a CRT, 4 is a display screen, 5a, 5b and 5c are ITVs.
A camera, 6 is an image processing unit, 7 is a monitor, 8a and 8b are strobe lights, 9, 9a, 9b and 9c are imaging areas, and 10
Is a CPU (central processing unit).

In the figure, in the CTR display device 1, a raster display screen 4 is displayed on the front surface of the CRT 3, and the display screen 4 is positioned within the outer frame 2.
Further, in order to image the CRT 1 and the outer frame 2 including the CRT 1 with a relatively high resolution, three CCD ITV cameras (hereinafter, referred to as “the CCD ITV cameras” arranged in the raster direction (horizontal direction) of the display screen 4).
Cameras 5a, 5b, and 5c are provided, and strobe lights 8a and 8b are arranged on both front sides of the CRT display device 1, respectively. As such a camera, for example, an ITV monochrome CCD camera XC-57 equipped with a 25 mm lens B2518 manufactured by Sony Corporation and having 510 × 492 pixels is used. As the strobe lights 8a and 8b, for example, strobes (SM-334H, SH-321 1 Joule) manufactured by Sovic can be used.

Under the control of the CPU 10, the cameras 5a, 5b, 5c arranged laterally in order from left to right in the drawing.
Captures an image of the imaging area 9 including a part of the tube surface of the CRT 2 and the left and right sides of the outer frame 2 including the tube surface as a whole. For example, in the case of the CCD ITV monochrome camera described above, these three cameras 5a, 5b, and 5c provide about 540 m.
An image is taken with a visual field of 150 × 112 mm from a position separated by m.
This field of view is the imaging region 9. And these cameras 5
The images a, 5b, and 5c share images of the image pickup area 9. That is, the left camera 5a is the left imaging region 9a, the center camera 5b is the central imaging region 9b, and the right camera 5c is
Captures the right imaging region 9c, respectively. Here, the image pickup area 9a of the camera 5a and the image pickup area 9b of the camera 5b partially overlap, and the image pickup area 9b of the camera 5b and the image pickup area 9c of the camera 5c also partially overlap. The image output of the cameras 5a, 5b and 5c is performed by the image processing unit 6.
Is supplied to the monitor 7 after being processed by the three cameras 5a,
Images of the imaging area 9 by 5b and 5c are displayed.

The strobe lights 8a and 8b are for illuminating an area including the positions of the upper and lower sides, the left and right sides of the display area 4 by the raster and the positions of the ridge lines of the outer frame 2.

Actually, 9 cameras are used in 3 rows and 3 columns in total, and 4 strobe lights are used in 2 rows and 2 columns in total, but for convenience of explanation, three cameras in the center row are used. And only two strobe lights are shown.

FIG. 2 is a block diagram of the embodiment of FIG. 1 showing the image processing unit more specifically. 11 is a test signal generator, 12 is a power supply driving unit, 13 is a camera selector, and 14 is a video frame. A memory, 15 is a parallel output interface, 16 is a bus, 17 is a RAM (random access memory), and the same symbols are given to the portions corresponding to FIG.

In FIG. 2, only two cameras 5a and 5b are shown here as cameras. The test signal generator 11 is connected to the CPU 10 via a control line of the communication circuit RS232C, and a control signal is supplied from the CPU 10 via this control line to generate a test signal of a white raster signal or a black raster signal. CRT
Supply to 3. As a result, the display surface of the CRT 3 shown in FIG.
As shown in, the raster display screen 4 is displayed.

When the image pickup command is output from the CPU 10 via the bus 16 while the display screen 4 is displayed on the CRT 3 as described above, a trigger pulse is output from the parallel output interface 15 to operate the power supply drive unit 12. The strobe lights 8a and 8b are turned on, and the camera 5
A, 5b, etc. start imaging in the imaging region shown in FIG. One of the image outputs of these cameras is selected by the camera selector 13 controlled by the parallel output interface 15, and one address is selected in the vertical and horizontal 512 × 512 addresses.
It is supplied to the high-definition video frame memory 14 of bytes. In the video frame memory 14, the selected image signal is converted into a digital image signal of 256 gradations and 512 × 512 pixels and stored. The video frame memory 14 is accessed from the CPU 10 via the bus 16 and can be passed or frozen after A / D conversion. Video frame memory 1
The digital image signal read from 4 passes through the bus 16, is D / A converted by the CPU 10, and is supplied to the monitor 7.

FIG. 3 shows the three cameras 5a and 5 shown in FIG.
It is the figure which showed the imaging area of b and 5c in more detail.

In the figure, the imaging area 9a of the left camera 5a has a height Wh and a lateral width W that connect points A, B, D, and C in order.
It is a rectangular area of Lx, and the imaging area 9b of the central camera 5b
Is a rectangular area having a height Wh and a lateral width WCx connecting points E, F, H, and G in order, and the imaging area 9c of the camera 5c on the right side is points I, L,
It is a rectangular area having a height Wh and a horizontal width WRx connecting K and J in order. The image pickup areas 9a and 9b are overlapped with each other in the area connecting the points E, B, D, and G in sequence, and the image pickup area 9a
b and 9c are overlapped in a region where points I, F, H, and J are sequentially connected. Here, the imaging area 9a is at least the CRT3.
Including the ridgeline of the outer frame 2 that forms a boundary with the tube surface of
c also includes at least the ridgeline of the outer frame 2 that forms a boundary with the tube surface of the CRT 3.

Therefore, the camera 5a picks up the image pickup area 9a and outputs image information, and this image information is stored in the video frame memory 14 and used for position measurement of the display screen. Points A, E of 9a,
An area having a height Wh and a lateral width Wlx in which G and C are connected in order is set as an effective image pickup area of the camera 5a, and image information of the effective image pickup area is used for position measurement of the display screen. Here, the straight line connecting the points E and G is the vertical reference line SL1, and the straight line connecting the points I and J is the vertical reference line SL2.
If the ridgeline of the boundary of 3 is FL1 and the ridgeline of the boundary of the right outer frame 2 and the CRT 3 is FL2, the tube surface portion of the CRT 3 in this effective imaging area, that is, the ridgeline FL1 and the reference line SL1.
The width between and is Lex. Similarly, the effective image pickup area of the camera 5c is an area having a height Wh and a lateral width Wrx in which the points F, L, K, and H in the image pickup area 9c are sequentially connected, and the image information of the effective image pickup area is displayed on the display screen. Used for position measurement. Here, the tube surface portion of the CRT 3 in this effective imaging area, that is, the lateral width between the ridgeline FL2 and the reference line SL2 is defined as Rex. On the other hand, the effective image pickup area of the camera 5b coincides with its own image pickup area 9b. The camera 5a,
The image sharing of the image capturing area 9 by 5b and 5c is divided by the reference lines SL1 and SL2.

When measuring the position of the display screen 4 projected on the tube surface of the CRT 3 with respect to the outer frame 2, the position of the ridge of the outer frame 2 and the position of the side of the display screen 4 are measured, and the distance between these positions is measured. Let the difference be the position of the display screen 4. When the distance differences are equal on all sides, the position of the display screen 4 is correct, and when they are not equal, position adjustment is performed.

Next, the measurement of the position of the ridgeline of the outer frame 2 and the position of the side of the display screen 4 will be described. First, the measurement of the position of the ridgeline of the outer frame 2 will be described.

In this case, first, as described above,
For example, the strobe light 8a manufactured by Sovic Co., Ltd. is turned on for 40 μsec to illuminate the outer frame 2 and the CRT 3, and a black raster signal is supplied from the test signal generator 11 to the CRT 3 as a test signal to generate a black raster. The display screen 4 is displayed on the CRT 3. This increases the contrast between the outer frame 2 and the CRT 3 when illuminated by the strobe light 8a. Moreover, since the outer frame 2 and the CRT 3 are illuminated obliquely from the front, a shadow is generated on the ridge line that is the boundary between the outer frame 2 and the CRT 3, and the ridge line of the outer frame 2 is clear. In this state, the left camera 5a captures an image of the imaging area 9a. The output image information of the camera 5a is stored in the video frame memory 14 of FIG. 2, then read by the CPU 10 and displayed as an image on the monitor 7, and the image processing described below is performed using the RAM 17. , The edge position of the outer frame 2 is detected. This ridge line position is the reference line S in FIG.
L1 is the reference position, and the distance L from this reference position SL1
detected as ex.

FIG. 4 shows a memory area 14L for storing digital image information for one image from the camera 5a in the video frame memory 14 shown in FIG. 512 pixels are stored. In this memory area 14L, if the horizontal axis is the i-axis and the vertical axis is the j-axis, the addresses in the i and j-axis directions are both 51
There are two.

When measuring the position of the ridgeline of the outer frame 2, the address of the center in the j-axis direction, that is, the pixel data at the address j = 256 may be used, but here, the surface of the outer frame 2 and the CRT 3 are used. In order to eliminate the uneven brightness on the tube surface, as shown in FIG. 4, the pixel data at the address (256 ± 5) on the j-axis are averaged and used. That is, when the value of the pixel data at the position (i, j) in the memory area 14L is M (i, j), the average value M of the values of the pixel data at the positions (i, 251) to (i, 261) is M. (I) is used instead of the pixel data at address j = 256. Here, if the number of pixel data to be averaged is N (i) and j ← (j-250), this average value M (i) is expressed by the following equation 1.

[0027]

[Equation 1]

However, in this case, N (i) = 11 FIG. 5A shows the above average value M (i) for the address in the i-axis direction of the memory area 14L in FIG. , M3 are the average values M (i) on the tube surfaces of the outer frames 2 and CRT3, and MFL1 is the average value M (i) of the ridge lines that are the boundaries of the tube surfaces of the outer frames 2 and CRT3. As described above, the shadow caused by the illumination of the strobe light 8a is lower than that of other portions.

With respect to the average value M (i) thus obtained, the absolute value ΔM (i) of the difference between the average values M (i) between the adjacent addresses i and i + 1 is then determined. Figure 5
As shown in (b), the maximum peak of the absolute value ΔM (i) of this difference occurs at the address iFL1 whose average value M (i) in FIG. 5A is MFL1. Therefore, the reference line SL in FIG.
If the address for ₁ is i ₁ , the ridgeline of the outer frame 2 in FIG.
It is at the position of the number of addresses (hence, the number of pixel data) n obtained by FL1-i ₁ |.

Therefore, assuming that the optical resolution α per pixel is 0.3 mm, the distance Lex [mm] of the ridgeline of the outer frame 2 from the reference line SL1 in FIG. 3 is expressed by the following equation 2. Be done.

[0031]

[Equation 2]

Although the position of the ridgeline of the left outer frame 2 in FIG. 3 has been described above, the position of the ridgeline of the right outer frame 2 can be similarly obtained.

That is, in FIG. 3, the strobe light 8b is used.
Is lit for a period of, for example, 40 μsec and the outer frame 2 and the CRT are
And the imaging area 9c with the camera 8c on the right side.
Is imaged and the average value M (i) shown in FIG. 6A is obtained in the same manner as above. Then, from this average value M (i),
As described above, the absolute value ΔM of the difference shown in FIG.
Find (i). Maximum peak right indicates the ridge line of the outer frame 2, out of these reference line SL2 from the address i ₂ Metropolitan right for this address iFL2 the reference line SL2 in FIG. 3 of absolute value .DELTA.M (i) of this difference The pixel data number m up to the ridgeline of the frame 2 is obtained. Therefore, since the optical resolution α per pixel is set to 0.3 mm, the distance Rex [mm] of the ridgeline of the right outer frame 2 from the reference line SL2 in FIG.
It is represented by.

[0034]

[Equation 3]

As described above, the reference lines SL1 and SL2
The positions of the left and right outer frames 2 with respect to are obtained as the distances Lex and Rex. Such distance data is temporarily stored in the RAM 17 of FIG.

Next, the case of obtaining the position of the side of the “display screen on the CRT 3” will be described. In this case, in FIG. 2, the test signal generator 1 is controlled by the CPU 10.
1 generates a white raster signal as a test signal, and C
Supply to RT3. As a result, a white raster display screen is displayed on the tube surface of the CRT 3. At this time, none of the strobe lights 8a and 8b are turned on. Therefore, the brightness of the display screen 4 is much higher than that of other parts (the part other than the display screen 4 on the tube surface of the CRT 3, the outer frame 2, etc.).

FIG. 7 shows such a display state in the CRT device 1. 4L and 4R are the left side and the right side of the display screen 4, respectively, and the same reference numerals are given to the portions corresponding to the above drawings. .. Further, the circles in the display screen 4 indicate pixels.

In the display state shown in FIG. 7, the display screen 4
When detecting the position of the left side 4L of the left side of the camera, the left camera 5a is detected as in the case of measuring the ridgeline position of the left outer frame 2.
(FIG. 1) images the imaging area 9a, and the output image information is taken in by the CPU 10 via the video frame memory 14 of FIG. The CPU 10 uses the same method as that described with reference to FIGS.

[0039]

[Equation 4]

However, M (i, j) 'is the value of the pixel data at the position (i, j) similar to the case of the above-mentioned expression 1. Also, N
(I) = 11, the average value M (i) 'of the pixel data values as shown in FIG. 8 is obtained, and as shown in FIG. 8, the difference between the adjacent addresses of the average value M (i)' is obtained. Absolute value of Δ
Find M (i) '.

Since the display screen 4 is formed by the white raster, the average value M (i) 'greatly changes at the position of the left side 4L of the display screen 4, as shown in FIG. The largest peak occurs at the value ΔM (i) ′. Therefore,
Assuming that the number of addresses between the address of the position of the reference line SL1 and the address of the position of the maximum peak, that is, the number of pixel data is n ', the above optical resolution α per pixel is 0.3 mm. , The distance Lex 'from the reference line SL1 in FIG. 7 to the display screen 4L is obtained by the following equation 5.

[0042]

[Equation 5]

Similarly, the display screen 4 consisting of a white raster is displayed on the CRT 3, and the image pickup area 9c is picked up by the camera on the right side to obtain image information, whereby the average value M (i) is obtained as shown in FIG. 'And the absolute value ΔM (i)' are obtained, the pixel data number m'from the reference line SL2 in FIG. 7 to the right side 4R of the display screen 4 is obtained, and by using this, the following equation 6 is calculated. From these reference lines SL2 to the right side 4 of the display screen 4
A distance Rex 'to R is obtained.

[0044]

[Equation 6]

The distances Lex ', R obtained as described above
The data of ex 'is temporarily stored in the RAM 17. Then, the distance Lex from the reference line SL1 to the ridgeline of the left outer frame 2
And the distance Lex ′ to the left side of the display screen 4, the distance ΔL between the ridgeline of the left outer frame 2 and the left side of the display screen 4 is obtained from the following equation 7.

[0046]

[Equation 7]

Similarly, from the reference line SL2 to the right outer frame 2
Rex to the ridgeline and the distance R to the right side of the display screen 4
From ex ′, the distance ΔR between the ridgeline of the right outer frame 2 and the right side of the display screen 4 is obtained from the following equation 8.

[0048]

[Equation 8]

Then, the obtained intervals ΔL and ΔR are compared, and when ΔL = ΔR, it is determined that the position of the display screen 4 in the left-right direction with respect to the outer frame 2 is symmetrical. When ΔL ≠ ΔR, the horizontal position of the display screen 4 may be adjusted by a means such as a conventional screen position adjusting mechanism.

Either of the detection of the side position of the display screen and the detection of the ridge line position of the outer frame 2 may be performed first.

Further, the position measurement of the display screen 4 in the horizontal direction has been described above, but the position measurement in the vertical direction can be similarly performed by using the camera arranged in the vertical direction.

As described above, according to this embodiment, a strobe light which can be turned on and off in an extremely short time and can be sufficiently illuminated in a short irradiation time is used as the illumination means, and the display screen 4 In order to measure the position of each side and the position of each ridgeline of the outer frame 2, at least one screen of each image needs to be captured, so that the screen position can be measured at high speed. It is possible to improve the speed by 40 times or more as compared with the conventional technology. In addition, for each side of the display screen 4, by making the display screen 4 have high brightness of the white raster,
It becomes very clear, and the ridgeline of the outer frame 2 becomes a shadow and becomes very clear by illuminating the ridgeline from the front with a strobe light. The position of the ridge can be detected with high accuracy, and the position of the display screen 4 can be measured with high accuracy.

The numerical values shown in the above description of the embodiments are merely examples, and the present invention is not limited to these numerical values.

Further, in FIG. 4, among the pixel data stored in the video frame memory 14, what is actually used is the pixel data processed by the above equations 1 and 4, so that the video frame memory 14 is Need only have a capacity to store such pixel data. The pixel data of such an area can be easily identified from the scanning position of the camera.

[0055]

As described above, according to the present invention,
The positional relationship of the display screen displayed on the CRT screen with respect to the outer frame can be measured at high speed and with high accuracy.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a screen position measuring device according to the present invention.

FIG. 2 is a diagram showing a more specific configuration of the embodiment shown in FIG.

FIG. 3 is a diagram for explaining details of an image pickup area of each camera in FIG. 1 and an algorithm for detecting a position of a ridgeline of an outer frame.

4 is a diagram showing an area of pixel data used for detecting a ridgeline position of a left outer frame of image information obtained by imaging the left imaging area in FIG. 3;

5 is a diagram showing information data for detecting a ridge line position of a left outer frame, which is obtained by processing pixel data from the area shown in FIG.

FIG. 6 is a diagram showing information data for detecting a ridgeline position of a right outer frame.

FIG. 7 is a diagram for explaining an edge position detection algorithm of a display screen in the embodiment shown in FIG.

FIG. 8 is a diagram showing information data for detecting the position of the left side of the display screen.

FIG. 9 is a diagram showing information data for detecting the position of the right side of the display screen.

[Explanation of symbols]

 1 CRT display device 2 outer frame 3 CRT 4 display screen 5a, 5b, 5c camera 6 image processing unit 7 monitor 8a, 8b strobe light 9, 9a, 9b, 9c imaging area 10 CPU 11 test signal generator 12 power supply drive device 13 Camera selector 14 Video frame memory

Front page continuation (72) Inventor Hiroshi Maki 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Hitachi Ltd. Yokohama factory

Claims (4)

[Claims] 1. A screen position measuring device of a cathode ray tube display device for measuring a position of a display screen imaged on a tube surface of a cathode ray tube in a case frame, wherein each case frame is a boundary with the tube surface. Including the ridgeline of
At least four image pickup means each having a left side portion, a right side portion, an upper side portion, and a lower side portion of a display area of the display screen as image pickup areas; and a plurality of strobe lights arranged obliquely in front of the tube surface, A first mode in which a predetermined strobe light is turned on for each image pickup means to perform an image pickup operation of the image pickup means, and a display screen of a uniform high-intensity raster is projected on the tube surface to display the image pickup means. Control means for selectively setting a second mode for performing an imaging operation, information processing of output information of the imaging means in the first mode and output information of the imaging means in the second mode, and display A screen position measuring device comprising: a processing unit that creates position information of a screen within a case frame. 2. The control unit according to claim 1, wherein the control unit selectively lights the strobe light so that a shadow is formed on a ridge line of the case frame in an image pickup area of the image pickup unit that performs the image pickup operation. Screen position measuring device. 3. The screen position measuring device according to claim 1, wherein, in the first mode, the display screen is composed of a black raster. 4. The screen according to claim 1, wherein the image pickup unit is a CCD camera of 510 × 492 pixels, and the processing unit includes a high precision video frame memory of 512 × 512 pixels. Position measuring device.