JP2002228416A - Projector and method for acquiring dimension calibration correction value of chart image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector in which the projected image of an object can be compared with a chart as a reference without using a sheetlike chart. SOLUTION: The projector is provided with a stage 120, a display element 230, a display controller 210 and a display controller 220 which plot and process a chart image to be displayed on the display element 230 and a projection system 140 by which the projected image and the display image of the display element are projected on a projection plane. The stage 120 moves a specimen in the X- and Y-directions, and it comprises a measuring device 123x and a measuring device 123y which measure the movement amount of the specimen. The display controllers display, on the display element, a reference graphic whose dimensions are known, they receive the input of information indicating the movement amount measured by the measuring devices, and they find a magnification correction value while the pattern dimensions of the reference graphic obtained on the basis of the movement amount and the pattern pixel size, displayed on the display element, of the reference graphic are used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for projecting an image of an object when inspecting, measuring, etc. the object.
The present invention relates to a technique that can be used for performing inspection, measurement, and the like by comparing and contrasting an object image with a reference graphic called a chart.

[0002]

2. Description of the Related Art A projector comprises a screen, a mounting surface on which a target object (object to be measured) is mounted, an illuminating unit for illuminating the object to be mounted mounted on the mounting surface, and an illumination unit. An enlarged projection optical system that projects an enlarged image of the object to be measured illuminated by the unit on a screen.

[0003] As a method of making a pass / fail determination of the dimensions of a device under test using a projector, there is a comparative measurement called a chart measurement. This means that a sheet called a chart is pasted on the screen of the projector, and if the image of the DUT falls within the range of the engraved line indicating the dimensional tolerance of the DUT drawn on the chart, it is judged as pass. Is what you do.

[0004]

When a chart is measured by a projector, an operation of pasting a chart corresponding to an object to be measured on a screen is performed. In general, the chart is different for each device under test, so it is necessary to change the chart each time the device under test changes. In addition, even if the measurement target is the same, if the magnification is increased to ensure accuracy or the like, a corresponding chart must be prepared for each measurement location, that is, for each portion to be enlarged and projected. Of course, every time the magnification is changed or whenever the enlarged portion is changed, it is necessary to change the magnification to the corresponding chart.

[0005] In addition to the trouble of changing the chart, there is a problem of storage management of the chart itself. That is,
A plurality of charts are provided for each portion to be measured, for each magnification, and for each enlarged portion. Therefore, many charts exist. As a result, there is a problem in that it takes time and effort to save and manage the chart as the number of parts to be measured increases.

An object of the present invention is to provide a projector capable of comparing a projected image of an object with a reference chart without using a sheet-like chart.

[0007]

To achieve the above object, the present invention provides a projector for projecting an image of an object to be measured on a projection surface, wherein the object to be measured is placed and moved in a predetermined direction. Stage, a display element that displays a chart image, a display control device that performs drawing processing of a chart image to be displayed on the display element, and a projection image of the device under test and a display image of the display element on the projection surface. Projection means for projecting, and a measuring device for measuring the amount of movement of the stage, wherein the display control device displays a reference figure having a known size on a display element and is measured by the measuring device. A magnification correction value is obtained by using a measured dimension of the reference graphic obtained based on the movement amount and a pixel size when the reference graphic is displayed on a display element.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment of the present invention, an example will be described in which magnification correction can be performed so that the size of the chart image displayed on the screen accurately corresponds to the actual size.

In the following embodiment, an image of a target object (object to be measured) is projected, and an image of a reference figure (chart) is displayed so as to be superimposed on the projected image, thereby measuring and inspecting dimensions of the target object. Will be described as an example.
Of course, the invention is not limited to such measurements and inspections.

FIG. 1 is a diagram showing a configuration of a projector according to an embodiment of the present invention. The projector shown in FIG. 1 includes a part of the original projection device 100 that projects an object to be measured, and an image display device 200 that displays a chart image showing a chart so as to be observable on a projection plane of the projection device.

The projection apparatus 100 includes an illumination system 110 for illuminating an object to be measured, and a stage 12 for mounting the object to be measured 500.
0, and projection systems 140A and 140B that project an object image and function as projection means for projecting a chart image.
A screen 150 for displaying a projected image of the device under test and a chart image.

The illumination system 110 has an epi-illuminator 111 for epi-illumination and a trans-illuminator 112 for trans-illumination.

The stage 120 has a feed mechanism 122 for each of the X and Y directions. In the present embodiment, an operation mechanism for performing a feed operation in each of the X and Y directions is provided. The feed mechanism 122 can position the measured object on the XY plane. Further, in the present embodiment, there is provided a measuring device for measuring the amount of movement of the feed mechanism in each of the X and Y directions. Specifically, the counters 123x, 123y
Is provided as a measuring device. In addition, stage 12
Although not shown in the figure, Z that moves in the optical axis direction is set to 0.
An axial feed mechanism is provided. Thus, the projection lens system 146 can be focused on the object to be measured. An object to be measured is placed on a test surface 121 of the stage 120.

As projection means, there are a first projection system 140A for generating a projection image of the object to be measured and a second projection system 140B for generating a projection image of a chart image. The first projection system 140A and the second projection system 140B are connected to the screen 1
At the time of projecting onto 50, they are arranged so that the optical axis is common.

The first projection system 140A has a projection lens system 146 for enlarging an image of an object to be measured and projecting the image on a screen 150, and a small mirror 141 and a large mirror 143. The mirrors 141 and 143 change the direction of the optical path, and can be increased or decreased as needed.
The projection lens system 146 includes a half mirror 147 for epi-illumination.

The second projection system 140B enlarges an image displayed on a liquid crystal display element 230, which will be described later, and projects a projection lens system 148 for projecting the image on a screen 150, and a light emitted from the projection lens system 148. It has a half mirror 144 that faces the large mirror 143 and transmits light from the small mirror 141. Here, the small mirror 143 is shared by the first projection system 140A and the second projection system 140B.

The screen 150 includes projection systems 140A and 140B.
Display the projected image and the chart image. In this embodiment, the screen 150 is provided as a single device in a common housing with the other components, that is, the illumination system 110, the stage 120, and the projection systems 140A and 140B. Of course, the screen 150 is
It may be provided separately from the housing in which 0A, B, etc. are stored. The projection image and the chart image are displayed on the projection surface 153 of the screen 150.

As shown in FIG. 1, the image display device 200 includes a liquid crystal display device 230, an information processing device 210 and a display drive circuit 220 which constitute a display control device for displaying a chart image on the liquid crystal display device 230. Having. The liquid crystal display element 230 is composed of, for example, a TFT color liquid crystal panel in which liquid crystal cells are arranged in a matrix. The present embodiment is a backlight-type liquid crystal display element that performs display by transmitted light. For this reason, a backlight 231 is provided. An image is displayed by allowing each liquid crystal cell to transmit or block light according to a display signal voltage applied from the outside. This liquid crystal display element 230
Are arranged at positions where the display image can be enlarged and projected by the projection lens system 148. Therefore, the liquid crystal display element 230
Is displayed on the projection surface 153 of the screen 150 via the second projection system 140B, that is, the projection lens system 148, the half mirror 144, and the large mirror 143.
Is projected and displayed. As a result, the projected image of the device under test and the chart image formed on the liquid crystal display element 230 are displayed on the same projection surface 153 of the screen 150.

The display drive circuit 220 is provided for the information processing device 21.
0 to generate a signal voltage for driving the liquid crystal display element 230 based on the image data from 0.
Drive.

The information processing device 210 is constituted by a general computer. For example, as shown in FIG. 2, an information processing device main body 211, a keyboard 212 and a mouse 2
13 and an external storage device 214 such as a hard disk device for storing programs, data, and the like. The information processing apparatus main body 211 includes a central processing unit (CPU) 211a that performs various processes, and a CPU 211a.
Read only memory (RO)
M) 211b and random access memory (RAM) 2
11c.

The information processing device 210 is connected to the original chart data holding device 300, the display drive circuit 220, and the counters 123x and 123y. In addition,
The counters 123x and 123y each have a count value of 0.
Is provided. Note that the value at the time of reset may be a specific preset value instead of 0.

In the present embodiment, the original chart data holding device 300 stores original chart data, which is graphic data serving as a reference to be compared with an object to be measured. The device 300 is configured by, for example, a CAD system. The original chart data includes, for example, design data of the device under test. A chart image is generated based on the design data. The original chart data is stored in a file for each DUT. In the present embodiment, the original chart data holding device 300 is provided independently, but the information processing device 210 may store the original chart data.

In this embodiment, a liquid crystal display element 230 is connected as a display device. However, a display device unique to the information processing device 210 may be separately connected. It is possible to display a chart image on the display device. However, a projected image of the device under test is not displayed.

In this embodiment, a program to be executed by the information processing device 210 is installed in the external storage device 214. This program, for example,
It can be obtained by reading from a storage medium such as a CD-ROM or by downloading via a network. For example, it includes a program module that realizes a function as shown in FIG. That is, it has a menu display process 2110, a chart image display correction value acquisition process 2120, and a chart image display process 2130. In the chart image display correction value acquisition processing 2120,
Operation guide display processing 2121 and magnification correction value calculation processing 2
122. The chart image display processing 2130 includes:
For example, processing as shown in FIG. 6 described below is performed.

The screen 1 is displayed by the image display device 200.
What is displayed at 50 differs depending on the data held in the original chart data, but at least a chart image is displayed. In addition, additional display of character data or the like can be performed. In the present embodiment, the additional display data can display the file name of the original chart data, the name of the device under test, the code, the application, and other notes. Character data etc. are attached display unit (not shown)
Can be displayed. Ancillary display,
A configuration in which a window is provided and displayed can be adopted.
In this way, the display position can be determined independently of the chart image. Also, by changing the size of the window, the number of characters that can be displayed can be increased or decreased. Further, it is also possible to divide the accompanying display data into a plurality of hierarchies and, correspondingly, to arrange the windows in a hierarchical structure so that data of different hierarchies can be viewed by selecting a window.

Next, the operation of this embodiment will be described. In particular, the correction processing at the time of displaying a chart image will be further described with reference to FIGS.

Projection device 100 and image display device 200
Start together. Thereafter, the information processing device 210 displays the menu display processing program 2110 on the screen 150.
Is executed, the menu of the projector is displayed. Although not shown, the menu displays options for performing a chart image display correction value acquisition process or displaying a chart image for inspection and measurement, and accepts the selection. Here, it is assumed that the chart image display correction value acquisition processing has been selected. Note that this processing only needs to be performed when the apparatus is used for the first time, or when it is necessary to calibrate the correction value due to aging, changes in display conditions, and the like. Therefore, usually, this process is not selected, and an option for displaying a chart image for inspection and measurement is selected.

First, the operation guide display processing 2121 is executed. That is, as shown in FIG. 4A, the message 2 "Please place the reference work on the stage"
52 and an image of a button 253 for the user to confirm and input that the reference work has been placed. In response to this, the operator places the reference work on the stage 120. Here, examples of the reference work include a mark serving as a reference point for measurement, for example, a test sheet on which a cross line is drawn. The present invention is not limited to this. As the marker, a sheet displaying a lattice can be used instead of the crosshair.
Instead of a sheet, a block having a thickness, such as a crosshair, a grid, or a coordinate axis, which is a marker, may be used. Then, by instructing and clicking the confirmation button 253 displayed on the display screen with the mouse 213, the user inputs that the operation requested by the message has been performed.

[0029] In response, information processing device 210 displays the next screen. That is, as shown in FIG. 4B, an image of the reference figure 251 having a known dimension and a message 254 "Please align the cross to the left end of the reference figure" are displayed. In response to this, the operator moves the stage in the X (-) direction. Then, the cross is set as the specific point of the reference graphic and is aligned with the leftmost line. Then, the confirmation button 253 is clicked by the mouse 213.

In response to this, the information processing device 210 takes in the value of the counter 123x. At this time, the reset switch 123r is reset, and the counter 123 is reset.
The value of x may be set to an initial value, for example, 0.
Then, as shown in FIG. 5 (A), a message 255 "Please align the cross to the right end of the reference figure" is displayed on the projection surface 153 of the screen 153.

The operator moves the stage in the X (+) direction while watching the reference figure and the cross projected on the screen 150. Then, as shown in FIG. 5B, the cross is set as a specific point of the reference graphic and is aligned with the rightmost line. Then, the confirmation button 253 is clicked by the mouse 213. The information processing device captures the count value of the counter 123x at this time.

Then, the difference from the counter value taken in at the left end is obtained, and the width of the reference figure is measured. At this time, the actual length of each counter value is known, and the actual length of the reference graphic can be obtained from the difference between the counter values.

The information processing device 210 is a liquid crystal display device 230
The number of pixels corresponding to the unit size when displaying a graphic is known, and the number of pixels corresponding to the size of the graphic is determined.
As a result, a graphic having a predetermined size can be displayed on the liquid crystal display device 230.
Can be drawn.

If the size of the reference figure is, for example, 10 mm, and if the number of pixels corresponding to 1 mm is 100, the size of 10 mm is displayed on the liquid crystal display element 230 as a length of 1000 pixels. Is done.

In the liquid crystal display element 230, pixels (liquid crystal cells) are arranged in a matrix in the horizontal direction (X-axis direction) and the vertical direction (Y-axis direction). Are assumed to be equal. That is, the lengths corresponding to the same number of pixels in the horizontal direction and the vertical direction are equal.

Next, the information processing device 210 performs a magnification correction value calculation process 2122. This is achieved by obtaining the magnification correction value α by the following equation using the number of pixels (pattern pixel size) corresponding to the length of the reference graphic and the measured value of the width of the reference graphic (pattern size). Do.

Magnification Correction Value α = Pattern Pixel Size / Pattern Dimension (1) This magnification correction value α represents the number of corresponding pixels per unit size.

As described above, the number of pixels corresponding to the unit size is known, but here, the figure is displayed with the number of pixels corresponding to the length of the reference figure, and the known number is determined based on the actually measured size. That is, a correction value for the value is obtained.

The obtained magnification correction value α is stored in the external storage device 2
14 is stored. And at the time of inspection and measurement described later,
It is used as a correction value when a chart image is drawn and displayed. Note that this magnification correction value α is, in the case of a fixed magnification,
One type may be calculated. On the other hand, when changing the magnification, the processing described above is performed for each magnification, and a correction value is obtained for each magnification. That is, the information processing apparatus 210 performs a process of obtaining the magnification correction value α for each magnification of the projection system, and stores the obtained magnification correction value corresponding to the magnification.

Next, in the menu described above,
The case where the display of the chart image for measurement is selected will be described. Here, when the chart image is drawn on the display element, a size correction process is performed on the graphic element of the chart image using the magnification correction value. If the magnification correction value has not been obtained, no correction processing is performed.

First, an object to be measured in the projector is placed on the surface 121 to be measured of the stage 120, and the projection lens system 146 is focused to prepare for measurement. In this state, the object to be measured is illuminated by, for example, epi-illumination from the epi-illuminator 111, and the reflected light from the object to be measured is enlarged by the projection lens system 146 and projected onto the projection surface 153 of the screen 150. In this state, a projected image of the device under test can be seen.

Next, the measurement processing by the information processing device 210 is started. As shown in FIG.
0, first, a chart drawing data input process is performed (S2
131). For this purpose, an original chart list is displayed. Here, the original chart list is stored in the information processing device 2
10 stores it in the external storage device 214 in advance and displays it. Of course, the original chart data holding device 30
It may be read from 0 and displayed. The display of the original chart list is performed, for example, as shown in FIG. The data for generating the original chart list display screen is sent to the liquid crystal display element 230, and the original chart selection window 280 is displayed on the projection surface 153 of the screen 150. In the original chart selection window 280, for example, a message 281 "Please select an original chart" and a selection frame 282
Within the icon, an icon 284 indicating a plurality of files each storing the original chart data is displayed. In this state, it waits for selection by clicking the mouse 213. Here, when any of the original charts is selected, the data of the target chart is read from the file of the selected original chart.

Next, the information processing device 210 acquires information on the projection lens (S2132). This can accept input from the keyboard 212, for example. Note that information on the projection lens may be acquired in advance and stored in the storage device 214.

Next, the information processing device 210 acquires the above-described magnification correction value α (S2133). However, since this value has already been obtained, it is read from the external storage device 214. Further, the information processing device 210 acquires the center coordinates P0 of the liquid crystal display element 230 (S213).
4).

The information processing apparatus 210 acquires graphic information from drawing data, that is, original chart data (S21).
35). Then, the graphic elements are sequentially extracted from the graphic data, and the type of the element is determined (S
2136).

If the graphic element is a straight line, the drawing positions of its start point P1 and end point P2 are calculated (S2).
1371, S21372). That is, assuming that the coordinates of the center P0 are (P0x, P0y), the coordinates of the start point P1 obtained from the original chart data are (P1x, P1y), and the coordinates of the end point P2 (P2x, P2y), the start point of the drawing position to be obtained p1, the coordinates of the end point p2 (p1x, p1y), (p
2x, p2y) is obtained by the following calculation: p1x = (P1x-P0x) * α p1y = (P1y-P0y) * α p2x = (P2x-P0x) * α p2y = (P2y-P0y) * α. Then, the coordinates of p1 and p2 are obtained.

Here, assuming that the correction value for both the XY coordinates is α, the start and end points of the straight line are obtained using the xy coordinates of each point. Then, a straight line is drawn based thereon (S23373).

Next, it is checked whether or not all the figures have been drawn.
If not, the process returns to step 21345 to fetch the next graphic element and, depending on the type of graphic,
Performs processing for drawing. Here, if the figure is a circle, calculation is performed to determine the drawing position of the center point o of the chart and the size of the radius r (S21374, S2137).
5). That is, if the coordinates of the center point of the circle obtained from the original chart data are (Ox, Oy) and the radius is R, the coordinates (ox, oy) of the center point of the drawing position and the radius r
Is calculated by the following formula: ox = (Ox−P0x) * α oy = (Oy−P0y) * α r = R * α Then, the coordinates of o and the value of r are obtained. As a result, the circle specified by o and r is drawn on the liquid crystal display element 230 (S2137)
6).

Next, it is checked whether or not all the figures have been drawn.
If not, the process returns to step 21345 to fetch the next graphic element and, depending on the type of graphic,
Performs processing for drawing. Here, when the figure is an arc, calculations are performed to determine the drawing position of the center point o of the chart and the size of the radius r (S21377, S2137).
8). That is, if the coordinates of the center point of the circle obtained from the original chart data are (Ox, Oy) and the radius is R, the coordinates (ox, oy) of the center point of the drawing position and the radius r
Is calculated by the following formula: ox = (Ox−P0x) * α oy = (Oy−P0y) * α r = R * α Then, the coordinates of o and the value of r are obtained. As a result, an arc specified by o and r and the angle range is drawn on the liquid crystal display element 230 (S21379).

The above procedure is repeated to draw all the graphic data on which the chart image to be drawn is based, and then the process ends (S2138).

As described above, the correction value for calibrating the dimensions of the chart image in the present embodiment is obtained by projecting the image of the reference mark on the projection plane and also extracting the image of the reference figure having the known dimensions on the projection plane. To obtain information indicating a moving amount obtained by moving the projected sign from a specific point of the reference graphic to another specific point, and a pattern of the reference graphic obtained based on the moving amount. It can be obtained using the dimensions and the pattern pixel size at which the reference graphic is displayed on the display element.

In this way, a highly accurate chart image subjected to magnification correction is drawn on the liquid crystal display element 230, and is enlarged and displayed on the screen 150 by the projection system 140, so that the chart image and the object to be measured can be displayed. This can be used for comparison.

As described above, according to the present embodiment, the dimensions of the standard figure drawn on the liquid crystal display element 230 are actually measured, and the correction values are obtained. Even if there is a difference, the chart image can be drawn after correction. That is, since the size of the chart can be matched with the measured object, the inspection and measurement can be performed with high accuracy.

The half mirror 144 and the projection lens system 148 of the second projection system 140B
By changing the optical path length to 0, the magnification can be changed.

According to the present invention, since the chart is generated by the liquid crystal display device, there is no need for the physical work of pasting and replacing the conventional chart. Moreover, since the chart data can be converted into an electronic file by a computer or the like, instantaneous replacement and search of the data are easy. The chart data can be set to one for one measured object. For example, the chart data can be enlarged in calculation even when the use magnification is increased for the reason that measurement is performed with partially increased accuracy. As a result, the number of files can be minimized, which is advantageous in data management.

In addition, linking with CAD is easy, and CAD
It is possible to generate a chart image immediately from the data. This significantly reduces the cost and time of charting. Since color display of the chart, various band line displays, and the like are possible, it can be customized according to the preference of the operator, and improvement in the efficiency of the determination operation can be expected. Further, since the chart is generated inside the apparatus, there is no conventional chart sheet on the screen, so that the image of the measured object can be clearly observed.

In the above-described embodiment, the example having the screen for displaying the projection image has been described. The present invention is not limited to this. For example, a device without a screen can be used. That is, a configuration in which the projection image and the chart image are superimposed and displayed outside the apparatus may be adopted.
Further, when an inspection is performed on a large object that is not placed on the stage, the present invention is also applicable to projecting a chart image onto the object via a projection optical system and inspecting the object. In this case, the objective lens system and the illumination system can be omitted.

In the above-described embodiment, the movement amount of the XY stage is obtained by the counter, and the value of the counter is taken in by the information processing apparatus and used as calculation data. The present invention is not limited to this. For example, a configuration may be adopted in which the counter position is captured by manual input via a keyboard.

Further, in the above-described embodiment, the device under test is directly projected on the screen by the projection lens system. The present invention is not limited to this. For example, a configuration in which an objective lens system is used and a projection lens system is arranged on the image forming plane may be adopted.

[0060]

According to the present invention, a projected image of an object can be compared with a reference chart without using a sheet-like chart. Moreover, it can be easily performed.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of a projector according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating an outline of a hardware system configuration of an information processing apparatus used in the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a functional configuration realized by the information processing device;

FIGS. 4A and 4B are explanatory views showing an example of projection on a screen displaying a procedure in a preparation stage when dimensions of a reference graphic are actually measured.

FIGS. 5A and 5B are explanatory diagrams showing an example of projection on a screen displaying a procedure for actually measuring dimensions of a reference graphic.

FIG. 6 is a flowchart illustrating a processing procedure for performing drawing by performing correction based on a correction value when displaying a chart image.

FIG. 7 is an explanatory diagram showing an example of a screen for selecting an original chart for displaying a chart image.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 projection device 110 illumination system 111 transmission illumination 112 epi-illumination 120 stage 121 subject surface 122 feeding mechanism 123x, 123y counter 140 projection system 140A first projection system 140B second projection system 141 ... Small mirror 143 ... Large mirror 144 ... Half mirror 146, 148 ... Projection lens system, 150 ... Screen 153 ... Projection surface 200 ... Image display device 210 ... Information processing device 220 ... Display drive circuit 230 ... Liquid crystal display element 300 ... Original chart Data holding device

Claims (5)

[Claims] 1. A projector for projecting an image of an object to be measured on a projection surface, a stage on which the object to be measured is mounted and which can be moved in a predetermined direction, a display element for displaying a chart image, A display control device for drawing a chart image to be displayed on the display element; a projection unit for projecting a projected image of the device under test and a display image of the display element onto the projection surface; and a measurement for measuring a movement amount of the stage And a display control device that displays a reference figure having a known dimension on a display element, and a measurement dimension of the reference figure obtained based on the movement amount measured by the measurement device. A magnification correction value obtained by using a pixel size when the reference graphic is displayed on a display element. 2. The projector according to claim 1, wherein the projection unit is configured to project a projection image of the device under test onto the projection plane, and to display an image displayed on the display element. A second projecting means for projecting onto a projection plane. 3. The projector according to claim 1, wherein the display control device performs a process of obtaining the magnification correction value for each magnification of the projection system, and obtains the calculated magnification correction value. Which is stored in correspondence with a magnification. 4. The projector according to claim 1, wherein the display control device, when drawing a chart image on the display element, performs the following for a graphic element of the chart image. A projector that performs a size correction process using a magnification correction value. 5. A method for obtaining a correction value for calibrating a dimension of a chart image in a projector having a function of projecting the chart image on a projection surface, the method comprising: projecting an image of a reference mark on a projection surface; Projecting an image of a reference pattern having a known shape onto a projection surface, and acquiring information indicating a movement amount obtained by moving the projected sign from a specific point of the reference pattern to another specific point; Using a pattern size of a reference graphic obtained based on a movement amount and a pattern pixel size in which the reference graphic is displayed on a display element, a magnification correction value is obtained, and the dimensions of the chart image are calibrated. How to get the correction value.