JP2000081593A - Projection type display device and video system using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a projection type display device which is capable of displaying projected images subjected to the correction of distortions according to device information by providing the device with a distortion information output means which outputs the information on the distortion of the images projected onto a surface to be projected. SOLUTION: When display is executed by inclining the projection type display device 1, the projected images are distorted to a trapezoidal shape and, therefore, whether the projection type display device 1 inclines with respect to a screen 2 or not is detected by a relative position detecting means 7 and the result of the detection, i.e., the device information is outputted to an image forming means 3 by a device information output means 9 and the video signal corrected in accordance with the device information is inputted to the projection type display device 1 so as to eliminate the distortions of the images projected onto the screen. The image forming means 3 is, for example, a personal computer or the like having a device information detecting means 10 which receives the device information from the projection type display device 1 and detects the state of the device and a control section 11 which corrects the images in accordance with the device information and outputs the video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection type display device for projecting an image generated on an image display device onto a projection surface by a projection optical system and enlarging and displaying the image, and a video system including the same.

[0002]

2. Description of the Related Art A projection-type display device for enlarging and displaying an image formed on a liquid crystal panel or the like via an optical system on a screen (projected surface) can provide a large screen, so that it can be used for presentations at conferences. It is used in viewing parties and the like.

FIGS. 12 to 15 show examples of use of a projection display device. In FIG. 12, reference numeral P001 denotes a projection display device, which forms an image on a liquid crystal panel or the like based on a video signal input from the outside, enlarges the image with an optical system P001a, and projects the image on a screen P002.

[0004] P003 is a device for sending a video signal to the projection display device, and may be, for example, a computer. In this case, an RGB signal is input to the projection display device P001 as a video signal, and the projection display device P001
Reference numeral 001 denotes an internal circuit (not shown) that performs processing in accordance with an input signal to create an image to be projected on the screen P002.

[0005] When a presentation is made in a conference room or the like using such a projection display device P001, even a person who is away from the screen P002 can use the screen P00.
In order to make it easy to see the image on 2, the projection type display device P001 may be inclined and projected as shown in FIG.

In this case, the screen is distorted because the screen P002 is inclined with respect to the projection optical system P001a. FIG. 14 simply shows the distortion on the screen that occurs at this time. P004 in FIG. 14 shows the shape of the screen on the screen formed when the projection optical system P001a is not tilted, and has a rectangular shape. P005 shows the shape of the screen when the projection optical system P001a is inclined, and the upper part of the screen extends longer and the screen is distorted into a trapezoidal shape. This distortion is hereinafter referred to as trapezoidal distortion.

There is a method of shifting an image display element such as a liquid crystal panel in order to project an image as high as possible and to prevent the projection optical system P001a from being inclined with respect to the screen P002. FIG. 15 is an explanatory diagram of a case where the image display element P007 is not shifted with respect to the optical axis P006 and a case where the image display element P007 is shifted. FIG.
(A) shows a case where the image is not shifted, and the center of the image display element P007 and the optical axis P006 coincide with each other.
A range P00 centered on the optical axis P006 even on the screen
An image is formed on 9a. FIG. 15B shows a case where the image display element P007 is shifted. Since the image display element P007 is shifted below the optical axis P006 as shown in FIG. P006
Is displayed in the upper range P009b. Therefore, an image can be displayed at a relatively high position without tilting the projection optical system P001a.

On the other hand, as a technique for correcting and displaying the trapezoidal distortion described above, Japanese Patent Application Laid-Open Nos.
There are techniques such as 275538 and JP-A-9-304733. In Japanese Patent Application Laid-Open No. 5-37880, a keystone distortion is electrically corrected. When an instruction is given from a correction amount instructing unit, pixels on the image display element are thinned and compressed according to the correction amount. The keystone distortion displayed on the screen is corrected by reading the data into the memory or by thinning out the data from the line memory.

In Japanese Unexamined Patent Publication No. 9-275538, an original image projected on a screen is converted into a horizontal image by a horizontal image converter to generate a horizontal converted image. Next, the horizontally-long converted image is corrected by a keystone distortion (trapezoidal distortion) correction unit to generate a corrected image. Then, the corrected image is displayed on the liquid crystal display panel. Also, Japanese Patent Application Laid-Open No. 9-3047
Reference numeral 33 denotes a projection optical system for projecting an original image on an object plane onto a screen, in which a group of optical systems is rotated to reduce distortion due to inclination of the optical system.

[0010]

Even in the case of an optical system in which the image display device shown in FIG. 15 is used by shifting it with respect to the optical axis, when the optical axis of the projection display device is inclined with respect to the screen, trapezoidal distortion occurs. Will occur. Further, even when the optical axis of the projection display device is not inclined with respect to the screen, the optical axis is different from the center of the image display element, and since the projection lens is used asymmetrically, distortion remains in the optical system. Image is distorted when it is displayed.

[0011] In the case of the technique disclosed in Japanese Patent Application Laid-Open Nos. 5-37880 and 9-275538, an input unit for performing pixel thinning and image conversion on a video signal input to a projection display device is provided. Since a correction process is performed between circuits for driving the display elements, the circuit becomes complicated.

In Japanese Patent Application Laid-Open No. 9-304733, the circuit and the like do not become complicated, but the optical system becomes complicated such as having a rotating shaft, and it is difficult to reduce the size and weight. In addition, by having an optical system for rotating, distortion generated due to the relative relationship with the screen can be reduced, but residual distortion or the like of the optical system cannot be removed.

It is an object of the present invention to provide a projection display device capable of displaying a projection image in which distortion has been corrected in accordance with device information, and a video system using the same.

[0014]

SUMMARY OF THE INVENTION A projection type display apparatus and an image system using the same according to the present invention have the following features.

[1]: In a projection type display device in which an image generated on an image display element is projected on a projection surface by a projection optical system and enlarged and displayed, distortion of an image projected on the projection surface. And a distortion information output means for outputting information relating to the image.

[2]: In a projection type display device, an image generated on an image display element based on a video signal input from the outside is projected on a projection surface by a projection optical system and enlarged and displayed. A projection type display device comprising: distortion information output means for outputting information relating to distortion of an image projected on a projection surface to the outside.

[3]: The information relating to the image distortion is:
The projection display device according to [1] or [2], wherein the information is information based on a relative position between the projection target surface and the projection optical system, characteristics of the projection optical system, or both.

[4]: The information based on the relative position between the projection surface and the projection optical system is information based on the inclination of the projection optical system with respect to the projection surface. Projection display device.

[5]: The information based on a relative position between the projection surface and the projection optical system is information based on a distance from a plurality of positions on the projection surface to the projection optical system. [3] The projection display device according to [3].

[6]: The information based on the relative position between the projection surface and the projection optical system includes the distance between the projection surface and the projection optical system on the optical axis of the projection optical system and the light. The projection display device according to [3], wherein the information is information based on a distance between the projection surface and the projection optical system on a straight line reaching the projection surface at a predetermined angle with respect to an axis.

[7] The projection display apparatus according to [3], wherein the information based on the characteristics of the projection optical system is information relating to distortion of the projection optical system.

[8] In a video system comprising the projection display device according to any one of [1] to [7] and an image generation device for inputting a video signal to the projection display device, An image generation device having a detection unit that detects information based on distortion of an image from the projection display device, and correcting a video signal input to the projection display device based on the detected information. A video system characterized by the following.

[0023]

[9] The video system according to [8], wherein the image generation device is provided outside the projection display device separately from the projection display device.

[10]: The image signal is corrected by correcting the image signal according to the distortion of the image projected on the projection surface and displaying the image on an image display element, thereby distorting the projected image. Characterized by offsetting

[9]
The described video system.

[11]: The image signal is corrected by converting a portion of the image projected on the surface to be projected, which is extended due to distortion, into a small image and displaying the image on an image display device. Characterized by offsetting the distortion of

The video system according to [9] or [10].

<Operation> Factors causing distortion of the projected image include the positional relationship between the projection display device and the screen (projected surface) and the characteristics of the optical system. If the image is corrected in reverse with these information, the projected image will not be distorted.

These pieces of information are transmitted by the device information output means to an image generating apparatus having an external device information detecting means. By transmitting the video signal, which has been corrected in reverse to the distortion, to the projection display device based on the transmitted information, an undistorted image is formed on the screen.

[0028]

FIG. 1 is a diagram showing a schematic configuration of a first embodiment according to the present invention. In this embodiment, a presentation system is configured as a video system including the projection display device of the present invention.

In FIG. 1, reference numeral 1 denotes a projection display device, 2 denotes a screen on which an image is projected by the projection display device 1, and 3 denotes an image generation device which inputs the image as a video signal to the projection display device 1. It is.

An image display element 13 for displaying an image to be projected and a projection optical system 1a for enlarging and projecting an image formed on the image display element 13 onto a screen 2 are provided inside the projection display apparatus 1. have.

The projection optical system 1a includes, in addition to the projection lens 4, a color combining optical system 12 and an illumination optical system (not shown) for illuminating the image display element 13.

Reference numeral 8 denotes a projection display device control circuit including an image display element driving circuit (not shown) for driving the image display element 13 in accordance with an input video signal.

The projection display device 1 receives a video signal from the image generation device 3 and causes the projection display device control circuit 8 to display an image on the image display element 13 based on the video signal. The image is enlarged and projected on the screen 2 via the color combining optical system 12 and the projection lens 4.

Since the image display element 13 has a rectangular shape, when the optical axis 6 is not inclined with respect to the screen 2, a shape substantially similar to the display element 13 is displayed on the screen. FIG. 3 shows a case where the projection display device 1 is projected while tilted. FIG. 4 shows the shape of an image in this case. 1
Reference numerals 5 and 17 denote images on the image display element 13, and reference numeral 14 denotes a projection image formed on the screen when the optical axis 6 of the optical system 1 a is not inclined with respect to the screen 2. Reference numeral 16 denotes a projection image formed on the screen when the projection display device 1 is tilted as shown in FIG. 3, in which trapezoidal distortion occurs. It should be noted that the projection height of the image 16 and the image 14 is also different due to the inclination of the projection display device 1, but they are overlapped here for explanation.

As described above, when the projection type display device 1 is tilted and displayed, the projected image 16 is distorted in a trapezoidal shape. In this embodiment, it is determined whether the projection type display device 1 is tilted with respect to the screen 2. The position detection unit 7 detects the detection result, that is, the device information is output to the image generation unit 3 by the device information output unit 9, and the video signal corrected based on the device information is input to the projection display device 1. To eliminate the distortion of the image projected on the screen.

The image generating means 3 includes the projection type display device 1
A device information detecting means 10 for receiving the device information from the device and detecting the state of the device, and a control unit 11 for correcting an image based on the device information and outputting a video signal. It is a computer or the like.

In this embodiment, the device information detected by the relative position detecting means 7 is the relative positional relationship between the projection optical system 1a and the screen 2, that is, the elevation angle and the depression angle information of the projection display device. Relative position detecting means 7 and device information output means 9
Is connected via the projection display device control circuit 8, and outputs the relative position to the outside (image generating means 3).

This output is detected by the device information detecting means 10 in the image generating means 3, and the amount of correction of the image is calculated from the amount, and the image is corrected to eliminate the trapezoidal distortion. At this time, the device information output unit 9 only outputs the amounts of elevation and depression, and the calculation of the correction amount and the correction of the image are performed on software operating on a control unit inside the image generation unit 3. . Therefore, the projection display device only displays an image in synchronization with the input signal.

Next, an outline of the relative position detecting means 7 will be described with reference to FIGS. The relative position detecting means 7 includes a distance measuring device 7a, and measures the distance to the screen 2 by the distance measuring means 7a. As shown in FIG. 3, the measurement rejection means 7a includes a distance L1 from an arbitrary point X (for example, the front principal point of the lens 4) of the optical system 1a to the screen 2 on the optical axis, and the arbitrary point X A distance L2 from the arbitrary point X to the screen 2 on a straight line 6 ′ having a certain angle θ with respect to the optical axis 6 is measured.

When the screen 2 is perpendicular to the optical axis 6, the distance L2 to the screen is L2 = L1 / cos θ.

Then, the difference ΔL2 between the actually measured distance L2 and that case is obtained, and ΔL2 = L2-L1 / cos θ The projection display device 1 for the screen 2 is obtained from the difference ΔL2.
Of the image plane 1b is obtained, and correction is performed based on the inclination α.

At this time, the inclination α and the distance L1 become device information (relative position).

As shown in FIG. 4A, the projection type display device 1
Has an elevation angle α, the projected image 16 is distorted into a trapezoid with a long upper base.

This is because the side P1 of the image 15 displayed on the image display element 13 is the side n1 of the projected image 16 and the side P1 of the image 1
5 is projected as the side n2 of the projection image 16, and the optical axis 6 and the straight line 6 ′ in FIG. 3 pass through the sides P1, n1 and the sides P2, n2, respectively: m = L1 / L1 ′ m ′ = L2 / L2 ′, and the sides p1 and p2 are projected m times and m ′ times, respectively, and n1 = m × p1 n2 = m ′ × p2 m × p1 <m ′ × p2 it can.

Then, the image on the side p2 side is deformed small,
It is displayed as a side p3, and the left and right are non-display areas 17b.
That is, if m × p1 = m ′ × p3 p3 = (m × p1) / m ′, the image 17 on the image display element 13 is projected onto the projected image 1
When projected as 8, a trapezoidal display area 17a and a non-display area 17b in which the upper side p3 of the image 17 is reduced,
Since the image 18 is projected as the display area 18a and the non-display area 18b, and the display area 18a has a rectangular shape, the image 18 is observed as an image having substantially no trapezoidal distortion.

In this example, the projected image 1
The distance to the side n2 of 8 is shown as being the same as the distance L2 obtained by the relative position detection means 7, but if this differs depending on the angle of view, the distance is obtained from the angle of view, the angle α, and the distance L1. Correction is performed in the same manner.

Next, the procedure of the correction is shown in FIG.

In STEP 1, image correction is started.

In STEP 2, the device information of the projection display device 1 is transmitted from the device information output means 9 to the device information detecting means 10.

In STEP 3, an image correction value is calculated in the image generation device based on the device information in STEP 2.

In STEP 4, image conversion is performed in accordance with the correction value.

At STEP 5, the corrected image is output in accordance with the video signal of the projection display device 1. Once the correction value is calculated, it is not necessary to recalculate the correction value until the relative position between the projection display device 1 and the screen 2 changes.
The image-converted output using this correction value is sent to the projection display 1.

As for the instruction to start the correction in STEP 1, a correction start switch (not shown) is provided on the projection type display device 1 side or the image generation device 3 side, and such a function is provided on the image generation device side. It should be done. In that case,
Means for causing the two devices to communicate in both directions is used.

In the present embodiment, correction of trapezoidal distortion has been described, but the present invention is not limited to trapezoidal distortion. FIG.
(A), the image display element 13 is shifted with respect to the optical axis 6 of the optical system 1a,
Is set so that the optical axis 6 of the image display device 1 is perpendicular to the screen 2.
FIG. 6B shows a case where the projected image is distorted due to the residual aberration of the projection optical system 1a. Reference numeral 19a denotes an output of the amount of residual image peculiar to the projection optical system to the image generating apparatus as device information, and a correction amount is calculated and corrected based on the output. As described above, it is possible to correct not only the relative positional relationship between the apparatus 1 and the screen 2 but also distortion inherent in the optical system.

Examples of the device-specific correction include not only distortion but also uneven brightness of a screen generated in an optical system.

As for these correction amounts, data or the like actually measured in advance may be stored in the device information output means in advance, and may be read out from the image generation device side. It should be noted that this device-specific correction is performed by the device 1 described above.
And the correction based on the relative positional relationship between the screen and the screen 2.

In this embodiment, the calculation of the image correction amount and the image conversion are performed by the image generating apparatus.
This processing is desirably performed on software. A general-purpose computer such as a personal computer or the like may be used as the image generation device, and the image generation may be performed using software accompanying the operating system or application software.

For correcting distortion inherent in the projection display device, even if the device information output means has information for calculating the correction amount, only the identification of the type of the projection display device is output to the device information output device. The same effect can be obtained even if the information is output by the means and the information about the correction amount corresponding to the output is given to the image generating apparatus. In that case, the characteristics of the optical system for performing the correction according to the type of the projection display device are stored in the image generation device side.

In the present embodiment, the relative position detecting means calculates the distance in two directions. As a method of measuring the distance, an autofocus device such as a camera or an autofocus device such as a video camera is used. Can be used, and the method is not limited.

<Embodiment 2> FIG. 7 shows a second embodiment according to the present invention.
An embodiment will be described. 7, the same reference numerals as those in FIGS. 1 to 6 indicate the same functions, and the description thereof will be omitted. This embodiment shows a configuration example in a case where a video signal of a television is viewed on a projection display device.

The video signal is input to the image generating device 3,
After being corrected in the image generating device 3, it is output to the projection display device 1. Projection display device 1 and image generation device 3
Are electrically connected to each other, as in the first embodiment, information on the relative positional relationship between the projection display apparatus 1 and the screen 2 or the quantity relating to the characteristics of the optical system of the projection display apparatus 1 or the projection. The identification of the type display device 1 can be communicated.
Based on this information, the image is corrected by the image generation device 3. The image generation device 3 is a general-purpose computer capable of inputting / outputting a video signal, and performs image conversion inside the computer.

FIG. 8 shows the structure of the relative position detecting means 7. Reference numeral 20 denotes an imaging lens which forms a projection image on the screen 2 on an imaging element. An image sensor driving circuit 22 and an image processing device 23 are connected to the image sensor 21.

The detection of the relative position in the present embodiment will be described. An image of a rectangular shape or the like is projected on the screen 2, and the image is formed on the solid-state imaging device 21 by the imaging lens 20. If the projected image is distorted, the image formed on the image sensor 21 is also distorted. Therefore, the relative positional relationship between the screen 2 and the screen 2 of the projection display 1 is determined based on the shape of the image. Can be detected.

In the case of this embodiment, since the amount of distortion of the projected image can be directly calculated, the amount of distortion or correction of the image can be transmitted without transmitting the amount related to the relative position to the image generating means. Correction according to the amount may be performed. Also,
Even when the screen 2 having the curved surface shape is used or when the screen 2 itself is distorted, the amount of distortion of the projected image can be directly calculated, so that the correction can be appropriately performed.

In this embodiment, there is an electrical connection for transmitting a video signal and device information between the projection display device and the image generating device. However, the two connections may be combined into one.

<Embodiment 3> FIG. 9 shows a third embodiment of the present invention. FIG. 9 shows a state in which the observer 33 arranges the projection display device 1 on the left side and displays an image on the screen 2 from above.

Reference numeral 35 denotes a line perpendicular to the screen 2, and the optical axis 6 of the projection display device 1 is inclined with respect to the screen 2 as shown. This is because the observer 33 tried to adjust the image center to the center of his / her line of sight. FIG. 10A shows the shape of the displayed image when no correction is made, and 38 is the image displayed at that time.

As shown in the drawing, trapezoidal distortion occurs in the lateral direction when viewed from the observer 33.

In the present embodiment, the image projected while being inclined in the horizontal direction is corrected. For the correction method and the detection of the relative position, the methods of the first and second embodiments can be used.

FIG. 10B shows an example in which image correction is performed based on the detected relative position information. FIG.
In (b), reference numeral 39 denotes a corrected and projected image area in which trapezoidal distortion has been corrected. Reference numeral 40 denotes a portion where no image is displayed by the correction at this time.

FIG. 11 shows an outline of the projection system at this time. A video signal 41 from a television or the like is input to the image generation device 3. The image generation device 3 and the projection display device 1 are electrically connected in the same manner as in the first and second embodiments. The image is output from the projection display device 1 and can be detected by the image generation device 3. The image generation device 3 corrects the image based on the device information of the projection display device 1 and outputs the resulting image to the projection display device 1 as a video signal.

In this embodiment, the video signal is input to the projection display device. However, the same effect can be obtained as long as the video signal can be sent to the image display device.

In the first to third embodiments, a liquid crystal panel can be used as the image display element. The liquid crystal panel may be a single-panel type in which an image is displayed by one liquid crystal, or a three-panel type in which three or more liquid crystal panels are used.

In the present invention, in order to correct trapezoidal distortion, an area where no image information is displayed is formed in a part of the image display device. For this reason, if the number of pixels of the image display element is sufficient for the amount of information of the input image, the lack of image information can be reduced. Therefore, it is desirable that the number of pixels on the image display element side be larger than the information amount of the input image.

In the present invention, the device information includes a value relating to the characteristics of the optical system of the projection type display device and the like and a relative positional relationship with the screen at the time of projection. This detection method is not particularly limited. In addition, as a matter of course, it is also possible to measure the relative positional relationship between the projection display device 1 and the screen 2 and correct the image by the image generation device 3 based on the measured relationship.

In this case, since the corrected video information is included in the video signal between the projection type image display device 1 and the image generation device 3, a corrected image is obtained.

[0077]

As described above, according to the present invention, it is possible to provide a projection type display device capable of displaying a projection image in which distortion has been corrected in accordance with device information, and a video system using the same. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a first embodiment according to the present invention.

FIG. 2 is an explanatory diagram of a relative position detecting unit.

FIG. 3 is an explanatory diagram when the projection display device is tilted.

FIG. 4 is an explanatory diagram of distortion of a projected image and correction of the distortion.

FIG. 5 is a flowchart of image correction.

FIG. 6 is an explanatory diagram of correction relating to distortion based on distortion.

FIG. 7 is a schematic diagram of Embodiment 2.

FIG. 8 is an explanatory diagram of a relative position detecting unit according to the second embodiment.

FIG. 9 is a schematic diagram of Embodiment 3.

FIG. 10 is a diagram illustrating distortion of a projected image and correction of the distortion.

FIG. 11 is a configuration explanatory view of a third embodiment.

FIG. 12 is a schematic diagram of a conventional projection display device.

FIG. 13 is a schematic view of a conventional projection display device.

FIG. 14 is an explanatory diagram of distortion of a projected image in a conventional projection display device.

FIG. 15 is a schematic diagram of a conventional projection display device.

[Explanation of symbols]

 P001 Projection display device P002 Screen P003 Image generation means P004 image P005 Image with trapezoidal distortion P006 Optical axis P007 Image display element P009 Screen 1 Projection display device 2 Screen 3 Image generation means 6 Optical axis 8 Projection display device control circuit 9 Projection information output unit 10 Device information detection unit 11 Control unit 12 Color separation system 13 Image display device 14 Rectangular screen 15 Image on image display device 16 Projection screen (no correction) 17 Image on image display device (correction) 18 Image display Projected image of element 19 Projected image (no correction) 20 Corrected image 21 Image sensor 22 Image sensor driving circuit 23 Image processing circuit 31 Projection display device 32 Screen 33 Observer 35 Screen and vertical line 36 Optical axis of projection display device 37 Untilted image 38 Projected image (no correction) 39 Projected image (correction) 40 Image non-display group 41 Video signal

Claims (11)

[Claims] 1. A projection display apparatus for projecting an image generated on an image display device onto a projection surface by a projection optical system and displaying the enlarged image, the distortion being related to distortion of the image projected on the projection surface. A projection type display device comprising distortion information output means for outputting information. 2. A projection display apparatus for projecting an image generated on an image display element on the basis of a video signal inputted from the outside onto a projection surface by a projection optical system and enlarging and displaying the image. A projection type display device comprising: distortion information output means for outputting information relating to distortion of an image projected on a surface to the outside. 3. The information related to the distortion of the image is information based on a relative position between the projection surface and the projection optical system, characteristics of the projection optical system, or both. 3. The projection display device according to 1 or 2. 4. The projection according to claim 3, wherein the information based on a relative position between the projection surface and the projection optical system is information based on an inclination of the projection optical system with respect to the projection surface. Type display device. 5. The information based on a relative position between the projection surface and the projection optical system is information based on distances from a plurality of positions on the projection surface to the projection optical system. Item 4. The projection display device according to Item 3. 6. The information based on a relative position between the projection surface and the projection optical system includes information on a distance between the projection surface and the projection optical system on the optical axis of the projection optical system, and information on the optical axis. 4. The projection type display device according to claim 3, wherein the information is based on a distance between the projection surface and the projection optical system on a straight line reaching the projection surface at a predetermined angle. 7. The information based on characteristics of the projection optical system,
4. The projection type display device according to claim 3, wherein the information is information on distortion of the projection optical system. 8. A video system comprising: the projection display device according to claim 1; and an image generation device that inputs a video signal to the projection display device. Detecting means for detecting information based on image distortion from the projection display device, and correcting a video signal input to the projection display device based on the detected information. Video system. 9. The video system according to claim 8, wherein the image generation device is provided outside the projection display device separately from the projection display device. 10. The distortion of the projected image is corrected by modifying the image signal and displaying the image on an image display element according to the distortion of the image projected on the projection surface. The video system according to claim 9, wherein 11. The distortion of the projected image by correcting a portion of the image signal projected on the surface to be projected on the projection surface by extending the portion to be reduced and displaying the image signal on an image display element. 11. The image system according to claim 9, wherein the image is canceled.