JP2001125737A - Projection image display device, presentation system and information storage medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection image display device capable of correcting the distortion of a projected image on a screen by utilizing a function for automatically detecting a pointing device by using a signal transmitted/received to/from a pointing means, that is impossible heretofore. SOLUTION: This projection image display device is provided with a projector 10 for projecting an image on the screen, plural position reference parts 30 provided on the screen for transmitting/receiving ultrasonic signals for pointing to/from a pointing stick 40, a digitizer 50 for detecting the pointing position on the image on the basis of the receiving time difference of the ultrasonic signals received by the plural position reference parts and a processing means for performing prescribed processing on the basis of the detected pointing position. The processing means projects an image for correction including plural reference points on the projecting means and corrects the distortion of the projected image on the basis of pointing position data provided by pointing the respective reference points by using the pointing means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type image display device for correcting distortion of an image projected on a screen, a presentation system, and an information storage medium.

[0002]

2. Description of the Related Art When an image is projected on a screen using a projector, an image is originally projected due to the projection angle of the image from the projector and the relative positional relationship between the projector and the screen. Images projected on a screen are often distorted.

[0003] Various proposals have conventionally been made for performing such distortion correction. However, using a system that automatically transmits and receives ultrasonic waves between a pointing rod as a pointing device and a plurality of ultrasonic microphones provided around the screen and automatically recognizes a pointing position, Conventionally, there is no device that performs distortion correction.

The present invention utilizes a non-conventional function of automatically detecting a pointing position using a signal transmitted / received to / from a pointing means, and can correct a distortion of a projected image on a screen. An image display device, a presentation system, and an information storage medium are provided.

[0005]

(1) In order to achieve the above object, a projection type display device according to the present invention comprises an image projection means for projecting an image on a screen, and different positions of at least one of the screen and its periphery. A plurality of position reference units that perform at least one of transmission and reception operations for transmission and reception of a pointing wireless signal with a pointing unit, a pointing unit, and the plurality of position reference units. Based on the transmission time difference of the transmitted and received wireless signal for pointing, based on the position detection means for detecting the pointing position on the image by the pointing means, and processing means for performing a given process based on the detected pointing position, The processing means causes the projection / projection means to project a calibration image including a plurality of reference points, Based on the pointing position data obtained by pointing with the pointing means a quasi-point, characterized in that it comprises a distortion correction unit which performs distortion correction of the projected image.

The present invention is also an information storage medium storing computer-usable information for controlling a projection type image projection apparatus for projecting an image on a screen, wherein the information storage medium stores at least one of the screen and its surroundings. A plurality of position reference units provided at different positions and a pointing unit for pointing a desired position of the image are transmitted / received for a pointing wireless signal, and between the pointing unit and the plurality of position reference units. Based on the transmission time difference of the pointing wireless signal transmitted and received, means for detecting a pointing position on the image, and a calibration image including a plurality of reference points is projected to the image projection device, and each reference point is Pointing position obtained by pointing using the pointing means And a processing unit for performing a given process based on the detected pointing position, the information including distortion correction means for performing distortion correction of the projection image based on the data, wherein information for realizing the processing is stored. And

Here, it is preferable that the distortion correction means is formed so as to correct the distortion of the projected image so that the reference position of the projected calibration image is in a regular arrangement.

In the projection display apparatus of the present invention, for example, when the presenter points to a desired position of an image projected on the screen using a given pointing means, for example, a rod-shaped pointing means, the pointing means and the screen side The wireless signal for pointing is transmitted and received between the plurality of position reference units arranged at the same time.

Then, based on the transmission time difference between the transmitted and received wireless signals for pointing, the pointing position on the screen is automatically detected by using a technique such as triangulation.

[0010] Then, given processing is performed based on the detected pointing position.

In the present invention, the distortion of the projected image on the screen is corrected by using such a pointing position detecting technique which has not been conventionally available.

That is, at the start-up of the projection type image apparatus or at any time after the start-up, the image projection means projects a calibration image forming a plurality of reference points on the screen.

Then, a reference point included in the projected calibration image is pointed by using the pointing means. Based on the pointing position data of each reference point of the projection image obtained at this time, distortion correction of the projection image is performed so that each reference position included in the calibration image projected on the screen has a regular arrangement. .

By performing such distortion correction,
Then, even when projecting a normal image on the screen,
By applying distortion correction under the same conditions, it is possible to display a good image without distortion on the screen.

The transmitting section of the pointing wireless signal may be provided in one of the pointing means and the position reference section, and the receiving section of the signal may be provided in the other.

[0016] More preferably, the pointing means may be formed so as to have the wireless signal transmitting means in the pointing portion. For example, when a pointing wireless signal transmitting unit is provided in the pointing unit of the pointing unit, the plurality of position reference units may be formed to include the signal receiving unit.

(2) The calibration image includes at least four reference positions as the reference positions, and the at least four reference positions are at least three on the same straight line.
It is preferable that the distortion correction means is arranged in the image so as not to be located more than one, and is formed so as to perform distortion correction of the projected image so that the reference position of the projected calibration image has a regular arrangement. .

That is, at least four reference positions are set in the calibration image, and the reference positions are arranged so that three or more reference positions do not exist on the same straight line.

By doing so, distortion correction of the projected image can be performed more reliably.

(3) The position reference section includes means for performing at least one of transmission and reception operations for transmitting and receiving a wireless signal for distance measurement to and from another position reference section, and a screen and its surroundings. An attachment portion detachably attached to at least one of the plurality of position reference units, wherein the position detection means causes the distance measurement wireless signal to be transmitted and received between the plurality of position reference units, and the position detection unit It is preferable to include a distance measuring means for measuring the distance of the pointing device, and to detect a pointing position on an image by the pointing means based on the measured distance and a transmission time difference of the pointing wireless signal.

The position reference unit includes means for performing at least one of transmission and reception operations for transmitting and receiving a wireless signal for distance measurement to and from another position reference unit, and at least one of a screen and its surroundings. An attachment portion detachably attached to the device, wherein the means for detecting the pointing position transmits and receives a wireless signal for distance measurement between the plurality of position reference portions, and performs position reference based on the transmission / reception time. Preferably, a distance between the units is measured, and a pointing position on an image by the pointing means is detected based on the measured distance and a transmission time difference of the pointing wireless signal.

For example, a configuration is adopted in which the user can arbitrarily attach the above-described position detection units to a screen and desired positions around the screen.

At this time, it is extremely troublesome for the user to measure the distance between the respective position reference portions each time and input the measured value to the device. On the other hand, according to the present invention, the intervals and relative positions of a plurality of position reference units attached at arbitrary positions are automatically determined by mutually transmitting and receiving wireless signals for distance measurement. As a result, there is no need for troublesome distance measurement or input of measurement data, and a projection type image display device and a presentation system using the same which are extremely convenient for the user can be realized. .

(4) The reference position is arranged in the calibration image as a reference position for determining whether or not the position reference unit satisfies an appropriate distance condition with respect to an image display area of a screen. The position detecting means, when each reference point of the calibration image is pointed by using the pointing means, detects a distance between a pointing position and the position reference part, and a measurement distance is given by a given distance condition. Is preferably determined to determine whether or not the above condition is satisfied.

The reference position is arranged in the calibration image as a reference position for determining whether or not the position reference portion satisfies an appropriate distance condition with respect to an image display area of a screen. The means for detecting a pointing position detects a distance between the pointing position and the position reference unit when each reference point of the calibration image is pointed using the pointing means, and the measurement distance is given. It is preferable to determine whether or not the distance condition is satisfied.

According to the present invention, when the mounting position of each position reference portion is, for example, too close or too far from the image display area of the screen, each position detecting portion is automatically determined. Attachment to an appropriate position with respect to the image display area makes it possible to reliably detect the pointing position.

(5) Further, the presentation system of the present invention is preferably formed using the above-mentioned respective projection type image display devices, thereby making it possible to realize an extremely convenient presentation system.

(6) In the present invention, part or all of the information stored in the information storage medium includes program codes, image information, table data, list data, and book codes for performing the processing of the present invention. The information includes at least one of information for instructing a process of the invention, information for performing a process according to the instruction, and the like.

In the information storage medium of the present invention, the information storage medium is preferably formed as a computer readable medium, and may be configured as one information storage medium, or divided into a plurality of hardware. It may be formed as an information storage medium installed. When the information is divided and arranged, each piece of the information is dispersedly stored in each divided information storage medium.

[0030]

Next, a preferred embodiment of a presentation system to which the present invention is applied will be described in detail with reference to the drawings.

(1) Overall Description FIG. 1 shows an example of a presentation system when a front-type image projection device is used as an image display device.

From the projector 10, a screen 20
A predetermined presentation image is projected on the image. At this time, the projection area of the image on the screen 20 becomes the display area 22. The projector gives a presentation to a third party while pointing a desired position of an image displayed on the screen with a pointing rod 40 functioning as pointing means. In the display area 22, image data provided from the personal computer 12 and other image supply devices may be projected by the projector 10 as an image, and predetermined image data stored by the projector 10 itself, for example, various calibrations Image data or message image data may be projected as an image.

In the system of the embodiment, when the presenter 2 points at a desired position on the screen 20 using the pointing bar 40, the pointing position P is automatically recognized by the system, and the cursor is moved so as to point to the pointing position P. 200 is displayed.
The cursor 200 is included in an image projected from the projector 10 and has a pointing position P
This position control is performed so as to indicate.

A third party listening to the presentation can easily recognize the pointing position by displaying the cursor 200.

The presenter 2 uses the cursor 2
00 is performed in combination with operations of a right-click function, a left-click function button, and the like (not shown) provided on the pointing rod 40. This operation signal is transmitted to the projector 10 and the personal computer 12. As a result, data processing similar to that performed when the mouse connected to the computer is right-clicked or left-clicked is performed on at least one of the projector 10 and the personal computer 12.

In the system according to the present embodiment, three position reference portions 30-1, 30-2, and 30-3 are detachably attached to desired positions of the screen 20, in this case, near each corner.

In this state, a wireless signal for pointing is transmitted from a transmitting section provided at the tip of the pointing rod 40, and this signal is transmitted to the position reference sections 30-1 and 30-.
2, 30-3.

The digitizer 50 functions as pointing position detecting means. Then, each position reference unit 30-
1, 30-2, and 30-3 determine the screen 20 based on the time difference of receiving the pointing wireless signal.
The upper pointing position is detected, and the detection signal is supplied to the projector 10.

The projector 10 controls the position of the cursor so that the cursor 200 included in the projection screen indicates the pointing position.

As described above, the presenter 2 points an arbitrary position on the screen 20 using the pointing bar 40, so that the pointing position is reliably recognized by the system and is reflected in predetermined data processing. Will be.

In particular, the presenter right-clicks and left-clicks the pointing position of the cursor 200 as necessary while pointing to a desired position on the screen displayed on the screen 20, so that the presenter is similar to a mouse connected to a computer. Operation can be performed, and an extremely convenient presentation system can be realized.

FIG. 2 shows a specific example of the pointing rod 40. An ultrasonic speaker 42 for transmitting ultrasonic waves as a pointing wireless signal is provided at the tip end of the pointing rod 40. The speaker 42 functions as a transmission source using ultrasonic waves. Various operation buttons 44 are provided on the grip side of the pointing rod 40.

By operating any of these operation buttons, a pointing wireless signal is transmitted from the ultrasonic speaker 42. By operating the other operation buttons 44, various operation signals are supplied to the projector, the personal computer 12, and the like via the digitizer 50. At this time, the pointing rod 40 and the digitizer 50
May be connected by a cable or the like,
In consideration of the operability of, the transmission and reception of signals between the pointing rod 40 and the digitizer 50 are performed using a wireless signal, here, wireless or the like.

In addition to this, the ultrasonic speaker 42 of the pointing rod 40 performs ultrasonic transmission for distance measurement and ultrasonic transmission for other data transmission separately, and transmits the transmitted ultrasonic waves. Received by the position reference unit 30 and digitizer 50
It may be configured to supply to the In this case, on the transmission side, an identification code for distinguishing the ultrasonic data for distance measurement from the ultrasonic data for other data transmission may be added to, for example, the head of each transmission data. Accordingly, the receiving side can distinguish and recognize whether the received ultrasonic wave is an ultrasonic wave for distance measurement or another ultrasonic wave for data transmission, and can perform necessary data processing.

(2) Pointing Position Measuring Principle Next, the pointing position measuring principle of the present embodiment will be described.

As shown in FIG. 3, each of the position reference portions 30
-1, 30-2, 30-3 are microphones 32 functioning as receiving units for receiving ultrasonic waves as wireless signals,
Each position reference unit 30 includes a speaker 34 that functions as a transmission unit that transmits a wireless signal for distance measurement (in this embodiment, an ultrasonic wave) for measuring an interval. The position reference unit 30 including the microphone 32 and the speaker 34 is formed as one unit, and is detachably attached to a desired position on the screen 20 using a clip or the like.

In this embodiment, each position reference unit 30-
1, 30-2 and 30-3 are positioned at desired positions of the screen 20,
In this case, it is preferable to attach the position reference portions 30-1 and 30-2 so that the line connecting the position reference portions 30-1 and 30-2 is parallel to the horizontal side of the screen 20. The line connecting -3 is the screen 20
It is more preferable to attach so as to be in parallel with the vertical side of.

After the mounting is completed, the ultrasonic digitizer 50 functions as a position detecting means, and
The wireless signals for distance measurement are transmitted and received while shifting the timing among 0-1, 30-2, and 30-3. The wireless signal used at this time is an ultrasonic signal. The ultrasonic wave transmitted from the speaker of the position detection unit 30 is received by the microphone 32 of another position detection unit 30. Since the speed of the ultrasonic wave is known, the ultrasonic digitizer 50 determines the position of each of the position detectors 30-1 and 30- based on the transmission time required for transmitting and receiving the ultrasonic wave as shown in FIG.
The respective intervals L ₁₂ , L ₂₃ and L _{13 of 2} , 30-3 are obtained.

The transmission speed of the ultrasonic wave varies slightly depending on the type of temperature, atmospheric pressure and the like. For this reason, the ultrasonic digitizer 50 has a temperature sensor 52 and an atmospheric pressure sensor 54, and the temperature detected by these sensors 52 and 54,
The ultrasonic velocity is corrected based on the atmospheric pressure, and the distances L ₁₂ , L ₂₃ , and L ₁₃ are accurately obtained.

In this manner, the three position reference portions 30-1, 30-2, 30-
When the distances L ₁₂ , L ₂₃ , and L ₁₃ between the three are measured, next, equidistant difference line information based on each of these position reference units 30-1, 30-2, and 30-3, that is, pointing Create a map to identify locations.

FIGS. 5 and 6 show specific examples.

First, on the map, a straight line passing through the two position reference units 30-1 and 30-2 is set as the x-axis, and the positions of the respective points are set as F 'and F. Then, on the map, an axis orthogonal to the center of the line connecting F ′ and F is represented by y
Axis. Here, F', spacing between F is L ₁₂ as described above, therefore, the relation c = L _12/2 is satisfied. Therefore, the coordinates of F 'and F on the screen are:
F ′ (− c, 0) and F (c, 0).

FIG. 3 shows a speaker 42, which is a pointing portion of the pointing rod 40, and position reference portions 30-1, 30-.
The relationship between the distances L1, L2, and L3 between 2, 3 is shown.

The speaker 4 provided at the tip of the pointing rod 40
When an ultrasonic wave is transmitted as a pointing wireless signal from 2, the ultrasonic wave is received by the microphone 32 of each position reference unit 30.

The ultrasonic digitizer 50 functioning as the position detecting means includes the position reference units 30-1, 30-2, 30-.
Transmission time T1, T of the ultrasonic wave received by the microphone 32
2. From T3, the tip of the pointing rod 40 and each position detecting unit 30
Distance between -1,30-2,30-3 L _1, calculates the L _2, L _3.

At this time, the ultrasonic digitizer 50 corrects the fluctuation of the transmission time of the ultrasonic wave based on the temperature and the atmospheric pressure detected by using the sensors 52 and 54, and
The arithmetic processing is performed so as to obtain L2 and L3 accurately.

When the story is returned to the equidistant difference line information shown in FIG. 5, for example, the pointing rod 40 and the position reference units 30-1 and 30-
If the difference between the distances L ₁ and L ₂ between the _two is set as 2a = (L ₁ −L ₂ ), the condition of the distance difference 2a is satisfied on the xy physical coordinate system on the screen 22. The equidistant line is given by: FIG. 5 shows that the difference between the distances is 2a.
3 is an example of an equidistant difference line. (X ² / a ² ) − (x ² / b ² ) = 1 (1) Here, the difference in distance is 2a, and b ² = c ² −a ² .

Thus, the position reference units 30-1 and 30-
The pointing position where the difference in distance from 2 is 2a is
It will be located on one of the equidistant difference lines 300-1 and 300-2 in FIG. Which equidistant line 300-
1, it is determined based on the plus and minus polarities of the distance difference 2a.

The ultrasonic digitizer 50 according to the present embodiment
A large number of such equidistant difference lines are obtained for each different distance difference, and these are stored in the memory. Instead of obtaining such an equidistant line in advance, a wireless signal for pointing is transmitted and received, and every time the distance difference 2a is obtained, the corresponding equidistant line is calculated based on the equation (1). May be configured.

Similarly, the position reference units 30-1 and 30-
The equidistant difference line information centering on 3 is created.

Then, as shown in FIG. 6, the equidistant difference line 300 specified based on the difference between the distances L ₁ and L ₂ and the distance L
_1, equidistant difference line 310 which is specified based on the difference in distance L ₃
The xy coordinates of the intersection with are obtained. The xy coordinates of this intersection are the pointing position of the pointing bar 40.

As described above, in the present embodiment, the pointing rod 4
0 and the position reference units 30-1, 30-2, and 30-3 using the ultrasonic waves transmitted from the speaker
Figure 5 the distance L _1, L _2, L ₃ between the measured, satisfies the difference in these distances, equidistant difference line shown in FIG. 6 300, 310
Ask for. Thus, the pointing position on the screen 20 can be accurately detected wirelessly as the coordinates of the intersection of the equidistant difference lines 300 and 310.

In particular, in the present embodiment, the ultrasonic waves emitted from the ultrasonic speaker 42 are transmitted to the position reference units 30-1 and 30-.
The distance difference 2a described above can be specified based on the time difference until the microphones 2 and 30-3 reach the microphone 32, and the pointing position can be detected using the equidistant difference line described above.
Therefore, there is no need to synchronize the transmitting side and the receiving side at all, and the pointing position can be detected without the digitizer 50 recognizing the transmission timing of the ultrasonic wave from the pointing rod 40. Therefore, if there is no need to simply transmit and receive data between the pointing bar 40 and the ultrasonic digitizer 50, the pointing bar 40 can be used completely free from physical separation from other devices. Thereby, a more convenient presentation system can be realized.

In particular, in the present embodiment, the transmission timing of the speaker 42 of the pointing rod 40 and the ultrasonic digitizer 50
Need not be synchronized, the circuit configuration can be simplified.

In this embodiment, the pointing wireless signal and the distance measuring wireless signal are
The case of using ultrasonic waves will be described as an example, but the present invention is not limited to this, and other wireless signals such as infrared rays may be used as necessary.

(3) Correction of Distortion of Projected Image Next, the correction of the distortion of the image projected from the projector 10 onto the screen 20 will be described.

The aspect ratio of the screen projected on the screen 20 may vary depending on the aspect ratio of the video signal input to the projector 10. Also, projector 1
The display image is not displayed exactly on the liquid crystal display screen of 0, but may be slightly shifted. In addition, even when a high-resolution video signal is input from the personal computer 12 to the projector 10 or when a low-resolution video signal is input, the projector 10 performs image display so as to have the same size as possible. Perform processing. However, in this case, the display size is logically changed on the personal computer 12 side. Further, the display image may be inclined or distorted, and the display image itself is not necessarily a rectangle.

For example, as shown in FIG. 1, the projector 10 often projects an image at a predetermined tilt angle with respect to the screen 20. In this case, as shown in FIG. 7, the projected image is ideally projected in a rectangular shape indicated by a broken line in the figure, but is projected in a trapezoidal shape as indicated by a solid line in the figure, causing distortion.

In the system according to the present embodiment, such distortion of the displayed image can be corrected by using the above-described pointing position detection technique, and a good rectangular image can be projected from the projector 10 onto the screen 20. It is assumed that.

Further, in the system of the present embodiment, it is possible to control the display of the cursor 200 so as to accurately indicate the pointing position of the pointing bar 40.

For this reason, in this embodiment, as shown in FIG. 7, four vertices A ₁ ′ and A
₂ ', A _3', to project the reference image with the A ₄ '. A ₁ ′, A ₂ ′, A ₃ ′, and A ₄ ′ are A ₁ , A ₂ , A ₃ , and A ₃ , when the reference image is ideally projected from the projector.
It is an image formed of a rectangular A _4.

According to the guide message projected on the screen as shown in FIG.
_{1 ', A 2', A} 3 ', A 4' pointing to four points. The pointing position data of the four vertices serves as reference position data for distortion correction, and is also used as data for associating the cursor position with the pointing position. In the present embodiment,
The screen shown in FIG. 9 is used as the reference screen. The details will be described later.

FIG. 8 shows a specific example of the processing in this case.

Here, the physical coordinates are coordinates defined by the positional relationship between the position reference unit 30 and the ultrasonic speaker 42 of the pointing rod 40. Here, the position reference units 30-1, 30-
2 are attached parallel to the horizontal direction of the screen, as will be described later, and the position reference units 30-1 and 30-3 are attached parallel to the vertical direction of the screen. Therefore, physical coordinates are given as two-dimensional coordinates of x and y on the screen. Specifically, the horizontal axis direction of the screen is x
The axis and vertical axis directions are given as the y-axis.

Here, the logical coordinates refer to the coordinate positions in the screen displayed on the screen.

The above-described distortion correction of the display image is performed,
Alternatively, in order to control the position of the cursor included in the display image, the physical coordinates of the screen 20 and the screen 2
It is necessary for the projector 10 or the personal computer 12 to recognize the correspondence between the logical coordinates of the image projected on the projector 10 and the personal computer 12.

For example, when a projector is projected over a projector, a displayed image is distorted into a trapezoidal or inverted trapezoidal shape. In order to prevent the displayed image from being distorted, it is necessary to perform distortion correction in which the projected image is inversely distorted and projected.

In this case, if the extent to which the image is distorted can be grasped, the correction amount can be automatically set. If a rectangular image is displayed on the screen in a trapezoidal shape when a rectangle is created with logical coordinates, the amount of distortion can be detected if the trapezoidal shape of the image in the physical coordinate system can be grasped. Usually, the distortion correction is performed inside the projector 10. When distortion correction of the projected image is performed, it is necessary to correct the logical coordinates on the screen. However, if the amount of distortion correction on the screen can be grasped, it is not necessary to perform a new calibration process. , The logical coordinates corrected by the calculation can be determined.

In order to perform such a process, a process for causing the projector 10 to grasp the correspondence between the physical coordinates of the screen 20 and the logical coordinates of the image projected on the screen as follows.

The position reference portions 30-1 and 30-2 are attached so as to be parallel to the upper side of the screen 20, and the positions 30-1 and 30-3 are parallel to the side of the screen 20. Attached to be. Therefore,
These position reference units 30-1 and 30-2 are parallel to the x-axis of the physical coordinate system, and 30-1 and 30-3 are parallel to the y-axis of the physical coordinate system.

Therefore, the pointing position on the screen 20 is detected as two-dimensional coordinates in the physical coordinate system xy.

In such a situation, the projector 10
For example, a reference image as shown in FIG. 8 is projected on the screen.
Then, the presenter gives each vertex A as described above.
₁´, A_Two´, A_Three´, A_FourPoint to these
Physical coordinates of each vertex (x₁, Y ₁) (X_Two, Y_Two) (X_Three,
y_Three) (X_Four, Y_Four) Is the vertex pointing position
Is detected.

From the data thus obtained, the physical
A displayed distorted on the coordinates xy ₁´, A_Two´, A
_Three´, A_Four'Image is parallel to each axis of physical coordinates x and y,
Distortion correction data for converting to a rectangular image
Create, cursor position and pointing position
Create data for associating with.

Based on the data thus obtained, the projector 10 projects a rectangular image without distortion on the screen 20 and controls the position of the cursor so as to accurately indicate the pointing position. Do.

The processing will be described below.

First, as described above, A ₁ ′, A ₂ ′,
The physical coordinates of each vertex of A ₃ ′ and A ₄ ′ are measured. Next, the following processes are performed.

First, a straight line connecting the midpoint TB1 of the lower line A ₁ ′, A ₂ ′ on the lower side of the logical coordinate area (projected image area) and the midpoint TU ₁ of the upper side A ₃ ′, A ₄ ′ of the logical coordinate area. Pull. It is determined whether the coordinates (x, y) of the target position are on the right or left of this straight line.

Next, TB2 and TU2 are set at the midpoint of the lower side and the upper side of the side where the coordinates (x, y) of the target position exist, with TB1 and TU1 interposed therebetween. A straight line connecting TB2 and TU2 is drawn, and it is determined whether (x, y) is on the right or left of this straight line.

Such an operation is continuously performed. As described above, when the distance between the straight line connecting the lower side and the upper side and the coordinates (x, y) of the target position becomes equal to or smaller than a certain value, the straight line passes through (x, y). The intersection of this straight line and the lower side is defined as TB. This physical coordinate is expressed as (TB
x, TBy).

The lower left (x
₁ , y ₁ ) and the ratio of the distance to the TB are (x, y) logical coordinates in the horizontal direction. That is, the logical coordinate Lx in the horizontal direction is
It is represented by the following equation. Lx = (TBx−x ₁ ) / (x ₂ −X ₁ ) (2)

The logical coordinates in the vertical direction are obtained by the same procedure.

As described above, in this embodiment, the physical coordinates x and y (coordinates on the screen) and the screen
The corresponding relationship with the logical coordinates of the display image above is obtained. For this reason, the data processing devices on the projector 10 and the personal computer 12 side can perceive the pointing position on the screen 10 as the coordinate position of the logical coordinate system in the display image and perform appropriate data processing. For example, make sure that the cursor 2
00 can be displayed.

FIG. 9 shows a series of menu screens for obtaining data for converting physical coordinates x and y into logical coordinates.

First, when the system is started, an image including a dialog box shown in FIG. 9A is displayed on the screen 20 from the projector 10.

In the present embodiment, the screen shown in FIG. 9 is used as the reference screen for distortion correction shown in FIG. Here, the lower left, lower right,
Top left, top right are vertices A1 ', A2', A3 of the reference screen
', A4'. A1 ', A2', A3 ', A4
'Is a rectangular image of A1, A2, A3, and A4 as shown in FIG. 7 when this screen is ideally projected from the projector.

When the presenter points at the start button and clicks it, an image including a dialog box shown in FIG. 9B is displayed next.

According to the instructions in the dial box shown in FIG. 9B, the presenter moves to the upper left corner (A3 ') of the image.
A pointing operation for detecting the physical coordinates x and y of the corner portion A3 'is performed by transmitting and receiving an ultrasonic wave with the tip of the pointing rod 40 positioned at the position. When the detection of the physical coordinates of the upper left corner A3 'is completed, a pointing instruction screen for the lower left corner A1', the lower right corner A2 ', and the upper right corner A4' is displayed in the same manner. In response to the above, the presenter points using the pointing rod 40 to point at the point designated, and performs a pointing operation to transmit the timing of the pointing to the digitizer side (transmit / receive the ultrasonic wave), and to perform the corner portions A1 ', A2', A4 'Physical coordinates x and y are detected.

If the distance between the corner portion and each position reference portion 30 is too short or too long during the pointing operation of the corner portion, it becomes difficult to transmit and receive appropriate ultrasonic waves. Therefore, the pointing rod 40 and each position reference unit 30
If the distance obtained by transmitting and receiving the ultrasonic wave is too short, a message screen as shown in FIG. 9C is displayed, and if it is too far, a message screen notifying the fact is displayed. .

Thus, the presenter can appropriately perform subsequent pointing position detection and data processing based on this by repositioning the position reference unit 30 to an appropriate position.

The above A ₁ ′, A ₂ ′, A ₃ ′, A ₄ ′
When the coordinate input of each point is completed, the screen shown in FIG. 9D is displayed, whereby the presenter can appropriately associate the physical coordinates x, y of the screen with the logical coordinates in the projected image. You can confirm that it has finished.

When the association between the physical coordinates and the logical coordinates is completed in this way, the ultrasonic digitizer 50 functioning as a position detecting unit converts the data of the detected pointing position in the physical coordinate system into the logical coordinate system. And outputs the data to the projector 10.

The projector 10 performs the following operations based on the thus obtained pointing position data of the logical coordinate system.
The position of the cursor 200 is controlled so that the cursor 200 indicates the pointing position.

At the same time, the distortion correcting means provided in the projector 10 corrects the distortion of the image of our company so that the projected image is projected as a regular rectangular image in the physical coordinate system of the screen. Perform processing.
Specifically, the vertices A ₁ ′, A ₂ ′, A ₃ ′, and A ₄ shown in FIG.
′ Are ideal rectangular vertices A ₁ ′, A ₂ indicated by broken lines in the figure.
′, A ₃ ′, and A ₄ ′ are subjected to projection-type distortion correction processing.

(4) Cursor Control Next, cursor control processing based on the detected pointing position will be described.

In the system of the present embodiment, a cursor control section is provided in projector 10.

The cursor control unit performs the cursor display based on the position data in the logical coordinates of the pointing position and the position data in the physical coordinates output from the digitizer 50 functioning as the position detection unit as described above. Is set, and the cursor position is controlled based on the set conditions.

In particular, in the present embodiment, the
Is input to the projector 10 and the projector 10
The position of the cursor 200 included in the display image is controlled using the cursor control unit provided in the inside.

As a result, for example, during the presentation, the presenter 2 is switched and the personal computer 1 to be used is changed.
Even if 2 is changed, the digitizer 50 and the personal computer 12
Since there is no need to change the wiring of the presentation, an extremely convenient presentation system can be realized.

When the processes (1) to (4) are completed,
In the system according to the present embodiment, a menu screen for setting cursor display conditions is displayed from projector 10.

First, a screen for allowing the user to select which side of the pointing position, the right or left side, the cursor is to be displayed is displayed. The user selects one of right and left using the pointing rod 40, operates a predetermined button of the pointing rod 21, and supplies the selection signal to the cursor control unit of the projector 10 via the digitizer 50. .

Further, as shown in FIG. 10, a screen for allowing the user to select the moving speed of the cursor is displayed. Here, the moving speed of the cursor can be selected from three types: low (L), medium (M), and speed (H).
The presenter selects one of these three speeds using the pointing bar 40. This selection signal is similarly supplied to the cursor control unit of the projector 10 via the digitizer 50.

Then, according to the cursor display conditions set in this manner, the cursor control unit sets the presenter 2
The display control of the cursor 200 is performed so that the pointing position P on the screen, which is pointed by using the pointing bar 40, is pointed to the right or to the left.

In particular, when making a presentation while standing on the right side of the screen, displaying the cursor 200 away from the pointing position P as shown in FIG. It is preferable for proper recognition from the display. When the presenter stands and gives a presentation, it is preferable to display the cursor 200 away from the pointing position to the right.

In the present embodiment, since such a selection can be made by the presenter 2, a presentation system which is extremely convenient for the presenter can be realized.

(5) Functional Block Diagram of Presentation System FIG. 11 schematically shows a functional block diagram of the presentation system of the present embodiment.

The system of the embodiment includes an input source 100 for supplying a projection image to the projector 10, an operation unit 110 for a user to input various operation signals, and a data processing unit 120 for performing various data processing.

The input source 100 includes a computer 12 for supplying image data and other image sources, for example, a video signal reproducing device.

As shown in FIG. 12, the processing section 120 includes a position detecting section 130 for detecting a pointing position.
And a cursor control unit 150 for controlling a cursor based on the detected position, and a data processing unit 170 for performing various data processing.

The position detecting section 130 is provided in the above-described digitizer 50 in the embodiment, and specifically includes a CPU,
This is realized using a ROM that stores various programs and data, a RAM that functions as a work area, and the like.

In the present embodiment, the cursor control section 150 and the data processing section 170 are integrally incorporated in the projector 10, and specifically, a CPU, an information storage medium ROM for storing various programs, data and the like. , Using a RAM or the like functioning as a work area.

Next, the position detecting section 130 will be described.

The position detecting section 130 of the embodiment comprises a position detecting data storage section 132, a sound speed correcting section 134 for correcting the sound speed of the ultrasonic wave based on the temperature, atmospheric pressure and the like detected by the sensors 52 and 54, and a position reference section. A measuring unit 136 for measuring the distance L, a calculating unit 138 for calculating the above-mentioned equidistant distance information, a pointing position calculating unit 140 for calculating a pointing position on the physical coordinate system x, y of the screen, and a pointing for the physical coordinate system. And a coordinate system conversion unit 142 for converting the position into the coordinate position of the logical coordinate system described above.

The sound speed data of the ultrasonic wave corrected by the sound speed correction unit 144 is stored in the storage unit 132.

The measuring unit 136 is used to start the system.
During start-up and periodically after system startup,
A wire for measuring the distance between the sub-sections 30-1, 30-2, and 30-3.
The transmission and reception of wireless signals (ultrasonic waves)
Each distance L shown in FIG. ₁₂, L_{twenty three}, L₁₃Measure
The measurement result is stored in the storage unit 132. put it here
The sound speed used for the distance calculation is determined by the sound speed correction unit 134
The sound speed of the ultrasonic wave calculated by the correction is used.

The equidistant distance information calculating section 138 uses the distances L ₁₂ , L ₂₃ , and L ₁₃ measured as shown in FIG. 4 to obtain the equidistant difference lines shown in FIGS. 5 and 6 as described above. 300, 31
Data of 0 is calculated and stored in the storage unit 132.

The pointing position calculating section 140 converts the ultrasonic wave (pointing wireless signal) transmitted from the speaker 42 of the pointing stick 40 into each of the position reference sections 30-1 and 30-3.
Based on the time difference received by 0-2 and 30-3 and the corrected ultrasonic propagation velocity stored in the storage unit 132,
The difference between the distances of L ₁ , L ₂ , and L ₃ , that is, (L ₁ −L ₂ ),
(L ₁ −L ₃ ) is obtained.

The distance difference obtained in this manner is compared with the equidistant difference line data shown in FIGS. 5 and 6 stored in the storage unit 132, and is compared with the physical coordinate system x, y on the screen 20. The pointing position is detected as the coordinate data in.

[0128] The pointing position thus obtained is determined by the cursor control unit 1 provided in the projector 18.
50 and the data processing unit 170.

Further, as described above, the coordinate conversion unit 142 converts the detected pointing position data of the physical coordinate system shown in FIG. 8 into coordinate data of the logical coordinate system of the projected image.
The pointing position data thus converted is similarly converted into the cursor control unit 150 and the data processing unit 170.
Output with.

Next, the cursor control unit 150 will be described.

The cursor control unit 150 of the embodiment includes a cursor display condition setting unit 152 and a display condition storage unit 154.
And a control processing unit 156.

As described above, the setting section 152 provides the player with an image for allowing the player to select whether to display the cursor 200 on the right or left side with respect to the detected pointing position, and the moving speed of the cursor. An image for selection is displayed on the screen via the projector. Then, the user uses a pointing stick or the like,
When a selection input of each selection item is performed, the selected data is written and stored in the storage unit 154 as a cursor display condition.

The control processing unit 156 includes the position detecting unit 13
0 is the pointing position detected, especially the coordinate system conversion unit 1
Based on the pointing position data converted and output by 42 and the cursor display condition stored in storage unit 154, display control of cursor 200 is performed so that cursor 200 indicates the pointing position on the screen.

In particular, in the present embodiment, the display of the cursor and the position control thereof are performed by the cursor control unit 150 provided in the projector 10.
Therefore, the personal computer 12 connected to the projector 10
Even when the position of the cursor 200 changes, the pointing position can be accurately recognized without being affected by the change, and the position of the cursor 200 can be controlled.

Further, the control processing unit 156 of this embodiment
Controls the cursor 20 to stop moving when the pointing position moves out of the display area of the projection image. Then, when the pointing position returns within the display image again, move the cursor to that position,
The movement of the cursor is controlled so as to indicate the pointing position.

As described above, by forcibly stopping the movement of the cursor when the pointing position moves out of the display image, it is possible to prevent a situation in which the cursor 200 moves without meaning in the display image. , For the user,
Also, it is possible to provide an image that is easy to view for a third person who views the screen.

Next, the data processing section 170 will be described.

The data processing section 170 of the embodiment includes a coordinate data conversion section 180 for converting the above-mentioned physical coordinate system into a logical coordinate system, and various processing sections for performing other processing.

The coordinate data conversion section 180 includes a correction data storage section 182, a conversion processing section 184, and a distortion correction condition data storage section 186.

In the storage unit 182, for example, data for displaying a calibration reference image as indicated by a solid line in FIG. 9 is stored. The correction processing unit 184 reads the data from the storage unit 182 when the system starts up. The image data is read and projected from the projector 10 onto the screen 20.

Then, according to the instruction of the dialog included in the reference image, the presenter operates the four corners A _{1 of the} projection image.
, A ₂ ′, A ₃ ′, and A ₄ ′ are pointed with reference to the reference position, the position data is stored in the storage unit 186 as data for calibrating the distortion correction conditions, and the storage unit 132.

Further, the correction processing unit 184 sets distortion correction conditions so that the calibration image is displayed in an ideal rectangular shape on the screen, and stores the distortion correction conditions in the storage unit 186.

At the time of normal image projection, an image supplied from an input source such as the computer 12 is corrected in accordance with the distortion correction conditions, and the image is projected from the projector 10 onto the screen 20 as a rectangular image without distortion.

Next, the operation of the presentation system according to the present embodiment will be described with reference to the flowcharts shown in FIGS.

FIG. 13 shows the basic operation of the system according to the embodiment.

First, when the system is started, various initial settings are made in step S10.
At 2, a normal presentation is made.

FIG. 14 is a detailed flowchart of the initial setting operation shown in step S10.

First, in step S20, each position detecting unit 3
Distance between _{0-1,30-2,30-3 L 12, L 23, L} 13
Is measured as described above.

Next, in step S22, the equidistant difference line data shown in FIGS. 5 and 6 is created using the above measured distance as described above.

Next, in step S24, the reference image shown in FIG. 9 is projected on the screen 20 from the projector 10, and the presenter uses the pointing rod 40 to select each vertex A ₁ ′, A ₂ ′, A _{2 of the} display image. ₃ ', a _4' by pointing to,
The user inputs the pointing position data.

This makes it possible to convert the pointing position from the physical coordinate system to the logical coordinate system.

In addition, the distortion of the image projected on the screen 20 from the projector 10 can be corrected.

At this time, the pointing positions at the corners of the projected image and the position reference units 30-1 and 30-
If the distance from 2, 30-3 is too short or too far, the user is notified of the fact. That is, a message indicating that the mounting position of the position reference unit 30 should be changed is projected from the projector 10 onto the screen 20 (step S26).

Thus, the position reference portions 30-1, 30-2, and 30-3 can be attached to appropriate positions on the screen 20.

Next, in step S28, the above-described cursor display conditions are set. Specifically, a selection screen for various cursor display conditions is displayed on the screen 20 from the projector 10, and the user inputs display conditions according to the selection screen. For example, a condition such as which one of the right side and the left side of the cursor is displayed with respect to the pointing position and a condition such as a level at which the maximum moving speed of the cursor is set are set as display conditions.

FIG. 15 shows the processing in step S12 shown in FIG.
2 shows an example of the detailed processing in.

First, in step S40, distortion correction is performed so that the projected image is projected on the screen as a rectangular image without distortion. This distortion correction is performed based on the distortion correction data obtained in the process of step S24.

Next, as shown in step S42, the position
Distance L between detectors 30₁₂, L_{twenty three}, L ₁₃Ultra for measuring
A transmission / reception operation of a sound wave is performed, and the obtained L₁₂,
L_{twenty three}, L₁₃The equidistant difference line information is re-created based on.

Next, in step S46, it is determined whether or not ultrasonic waves for pointing position detection have been transmitted / received from the pointing rod 40.

When it is determined that transmission / reception has been performed, that is, when a pointing wireless signal reception signal is detected from the microphones of the position reference units 30-1, 30-2, and 30-3, the next step is performed. In S48, the pointing position P on the screen is detected based on the detection time difference and the above-mentioned equidistant difference line information.

As described above, the position P is detected as position data on physical coordinates, and is also detected as coordinate data of logical coordinates constituting a projection image.

Next, in step S50, cursor position control is performed based on the detected pointing position data and the cursor display conditions set in step S28.

At this time, in step S52, it is determined whether the pointing position is inside or outside the screen. If it is outside, the movement of the cursor is forcibly stopped, and the meaningless cursor is stopped. To prevent the visibility of the screen from lowering due to the movement of the screen.

[0164] Such a series of operations is performed in step S56.
Repeat until the presentation is over.

(6) Hardware Configuration of the Processing Unit 120 In the above embodiment, a part of the processing unit 120 is arranged in the digitizer 50 and the rest of the processing unit 120 is
Although the case of dispersing and disposing them at 0 has been described as an example, the present invention is not limited to this, and the processing unit 120 may be integrally formed in, for example, the projector 10.

FIG. 16 shows the processing unit as the projector 1
An example of a hardware configuration when integrally formed in the area 0 is shown.

In the apparatus shown in FIG.
OM 1002, RAM 1004, information storage medium 100
6. Image generation IC 1010, I / O port 1020-
Are connected to each other via a system bus 1016 so that data can be transmitted and received. And I / O
Are connected to, for example, an operator operation unit, the computer 12, and other devices via the ports 1020-1, 1020-2,....

The information storage medium 1006 stores programs,
Image data and other data are stored.

The CPU 1000 controls the entire apparatus and performs various data processing according to a program stored in the information storage medium 1006, a program stored in the ROM 1002, and the like. The RAM 1004 is storage means used as a work area of the CPU 1000. Given contents of information storage medium 1006 or ROM 1002 or CP
The calculation result of U1000 and the like are stored. Further, a data structure having a logical configuration for implementing the present embodiment is constructed on the RAM or the information storage medium.

The various processes described with reference to FIGS. 1 to 5 are, specifically, an information storage medium 1 storing a program for performing the processes shown in the flowcharts of FIGS.
006 and the CPU 10 operating according to other programs
00, and is realized by the image generation IC 1010 and the like. The processing performed by the image generation IC 1010 and the like is executed by the CPU 1
000 or a general-purpose DSP or the like.

Note that a hardware configuration other than the above may be employed. For example, the image data may be sent to the projector 10 by the PC and written into the image-dedicated memory, read out again at a speed at which the liquid crystal display can display, and the image may be reproduced. In this case, these processes are
It is also possible to occupy a unique bus by hardware without using the U bus.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention.

For example, in the present embodiment, an ultrasonic wave is used as the wireless signal, but an infrared ray and other wireless signals may be used instead.

In the above-described embodiment, the case where two-dimensional pointing coordinates on the screen are detected has been described as an example. However, if necessary, the pointing position coordinates in the three-dimensional space may be detected using the same algorithm. It may be detected.

The case where the pointing means is provided with a transmission source of a wireless signal for pointing has been described as an example. However, if necessary, a transmission source may be provided on the position reference unit side.
The receiving means may be provided on the pointing means side.

In this case, it is necessary to output the signal received from the pointing means to the outside, and it is necessary to provide a means for outputting the information of the received signal to the pointing means. Inconveniences such as being unable to do so and shortening the battery life due to newly transmitting data from the pointing means occur.

The pointing means to be used may be of any shape other than the pointing rod.

Transmission and reception of ultrasonic waves from the pointing rod may be performed each time the operator operates a predetermined button, or may be automatically performed at a predetermined time, for example, at intervals of about 20 ms.

Further, as the image display means, other than the projector type, other image display means, for example, a direct-view CRT, a direct-view liquid crystal display panel, a PDP (plasma display panel) or the like may be used.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory diagram of a presentation system to which the present invention is applied.

FIG. 2 is an explanatory diagram of a pointing stick as pointing means used in the system shown in FIG. 1;

FIG. 3 is an explanatory diagram showing a relationship between a pointing rod and a position reference unit mounted on a screen.

FIG. 4 is an explanatory diagram of a distance between respective position reference portions mounted on a screen.

FIG. 5 is an explanatory diagram of an equidistant difference line used for detecting a pointing position.

FIG. 6 is an explanatory diagram of a case where a pointing position is detected using a plurality of equidistant difference lines.

FIG. 7 is an explanatory diagram showing a relationship between a distortion image projected on a screen and an ideal projected image.

FIG. 8 is an explanatory diagram of a correspondence relationship between logical coordinates of a projected image and physical coordinates on a screen.

FIG. 9 is an explanatory diagram of a screen projected on a screen when setting and inputting a correspondence between a physical coordinate system and a logical coordinate system;

FIG. 10 is an explanatory diagram of a screen for performing setting input of a moving speed of a cursor.

FIG. 11 is a functional block diagram of the system according to the present embodiment.

FIG. 12 is a detailed functional block diagram of a processing unit shown in FIG. 11;

FIG. 13 is an operation flowchart of the system according to the embodiment.

FIG. 14 is a flowchart showing a detailed process of step S10 in the flowchart shown in FIG. 13;

FIG. 15 is a flowchart showing a detailed operation of step S12 shown in FIG.

FIG. 16 is a schematic explanatory diagram of a hardware configuration of a processing unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Projector 20 Screen 22 Display area 30 Position reference part 32 Microphone 34 Speaker 40 Pointing rod as pointing means 42 Speaker as transmission source 44 Operation button 50 Digitizer 52 Temperature sensor 54 Barometric pressure sensor 120 Processing part 130 Position detection part 150 Cursor control part 170 Data processing unit 200 Cursor 300 Equidistant difference line

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B087 AA02 AD02 AD07 AE03 CC09 CC12 CC26 CC47 DD03 DE07 DG02 5C058 BA23 BA27 EA02 EA31

Claims (9)

[Claims] An image projection means for projecting an image on a screen, provided at at least one of different positions around the screen and its surroundings, for transmitting and receiving for transmitting and receiving a pointing wireless signal to and from the pointing means. A plurality of position reference units performing at least one operation, pointing means, and a pointing position on an image by the pointing means based on a transmission time difference of a pointing wireless signal transmitted and received between the plurality of position reference units. Position detecting means for detecting, and processing means for performing given processing based on the detected pointing position, the processing means, the projection means for projecting a calibration image including a plurality of reference points, Each reference point is obtained by pointing using the pointing means. And a distortion correction unit for correcting distortion of the projected image based on the pointing position data. 2. The image according to claim 1, wherein the calibration image includes at least four reference positions as the reference positions, and the at least four reference positions are not located on the same straight line in three or more positions. Wherein the distortion correction means corrects the distortion of the projected image so that the reference position of the projected calibration image is in a regular arrangement. 3. The position reference unit according to claim 1, wherein the position reference unit performs at least one of transmission and reception operations for transmitting / receiving a wireless signal for distance measurement with another position reference unit. Means, and an attachment portion detachably attached to at least one of the screen and the periphery thereof, wherein the position detection means causes transmission / reception of the wireless signal for distance measurement between the plurality of position reference portions, and transmission / reception thereof Including distance measuring means for measuring the distance between the position reference units based on time, based on the measured distance and the transmission time difference of the pointing wireless signal, to detect a pointing position on an image by the pointing means. Characteristic projection type image display device. 4. The calibration image according to claim 3, wherein the reference position is a reference position for determining whether the position reference unit satisfies an appropriate distance condition with respect to an image display area of a screen. The position detecting means, when each reference point of the calibration image is pointed using the pointing means, detects the distance between the pointing position and the position reference unit, the measured distance is given A projection-type image display device, which determines whether or not a distance condition is satisfied. 5. A presentation system using the projection type image display device according to claim 1. 6. An information storage medium storing computer-usable information for controlling a projection-type image projection apparatus for projecting an image on a screen, wherein the information storage medium is provided at at least one of different positions around the screen and its periphery. And transmitting and receiving a pointing wireless signal between the plurality of position reference units and a pointing unit for pointing a desired position of the image,
Pointing means, means for detecting a pointing position on the image based on a transmission time difference of a pointing wireless signal transmitted and received between the plurality of position reference units, and a calibration image including a plurality of reference points. Is projected on the image projecting apparatus, and based on pointing position data obtained by pointing each reference point using the pointing means, a distortion correcting means for correcting distortion of the projected image is included. A computer-readable information storage medium storing processing means for performing a given process based on: and information for realizing: 7. The calibration image according to claim 6, wherein the calibration image includes at least four reference positions as the reference positions, and the at least four reference positions are not located on the same straight line in three or more images. The information storage medium, wherein the distortion correction unit performs distortion correction of the projected image so that the reference position of the projected calibration image is in a regular arrangement. 8. The position reference unit according to claim 6, wherein the position reference unit performs at least one of transmission and reception operations for transmitting / receiving a wireless signal for distance measurement with another position reference unit. Means, and an attachment portion detachably attached to at least one of the screen and the periphery thereof, wherein the means for detecting the pointing position transmits and receives a wireless signal for distance measurement between the plurality of position reference portions. To measure the distance between the position reference units based on the transmission / reception time, and based on the measured distance and the transmission time difference of the pointing wireless signal, to detect a pointing position on an image by the pointing means. An information storage medium containing information. 9. The calibration image according to claim 8, wherein the reference position is a reference position for determining whether the position reference unit satisfies an appropriate distance condition with respect to an image display area of a screen. The means for detecting the pointing position, when each reference point of the calibration image is pointed using the pointing means, detects the distance between the pointing position and the position reference unit, the measurement distance An information storage medium for determining whether or not satisfies a given distance condition.