JPH06253241A - Projection distortion correction method for projection type display device - Google Patents

Abstract

PURPOSE:To measure a deflection angle of a screen and a deflection angle of a projector indirectly automatically by modifying a test pattern so that a projected shape of the screen is a specified shape with respect to a projection distortion correction method of the projection type display device. CONSTITUTION:A linear drawing picture angle calculation section 10 of a projector 2 including a liquid crystal display panel 4 and a projecting lens 3 generates a test pattern for two horizontal lines and vertical lines and its shape is projected onto a screen 1. Then the test pattern is adjusted by a linear drawing picture angle adjustment section 11 so that the test pattern indicates a specified shape when viewing from a viewer. In this case, a deflection angle of the projector 2 and the screen 1 is calculated from a set map transformation coefficient and when the value is set to a distortion correction arithmetic operation circuit 6, the correction processing of the projection distortion is executed and a video image with less distortion in a visual sense is displayed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection distortion correction method for a projection display.

[0002]

2. Description of the Related Art In recent years, displays have become larger, have higher image quality, and have higher functionality. Especially for larger screens,
A projection display device is used in which an optical image is formed on a light valve such as a liquid crystal panel, the optical image is irradiated with light, and an image is enlarged and projected on a screen by a projection lens.

FIG. 6 is an external perspective view showing a configuration example of a conventional projection display device. In the figure, a screen 1 is a screen for displaying an image projected by the projector 2. The projector 2 includes a projection lens 3, a liquid crystal panel 4, a backlight unit 5, a liquid crystal panel drive circuit 6, and the like. The video signal input from the outside is converted into a drive voltage by the liquid crystal panel drive circuit 6 and given to the liquid crystal panel 4. Then, in each pixel of the liquid crystal panel 4, the transmission characteristic changes corresponding to the input video signal. Light emitted from the backlight unit 5 is modulated to a predetermined brightness and color by the liquid crystal panel 4, and an image magnified by the projection lens 3 is displayed on the screen 1.

[0004]

However, in the projection display apparatus having such a configuration, it is necessary to install the projector 2 in front of the screen 1 (the normal vector of the screen surface and the normal line of the liquid crystal panel). Match the vectors). If not, projection distortion occurs in the image on the screen 1. Therefore, in some projection display devices, the distortion correction calculation circuit 7 is provided so that a normal image can be projected even if the projector 2 is installed not only in front of the screen 1.

Conventionally, the projection distortion generated when the projector 2 is installed other than in front of the screen 1 is manually corrected by using an adjustment dial (not shown) of the distortion correction calculation circuit 7 or the like. In this case, the positional relationship between the screen 1 and the projector 2 must be completely grasped in order to adjust the distortion correction. FIG. 7 is a side view showing an installation relationship between the projector 2 and the screen 1 when the projector 2 is installed on the floor surface, and FIG. 8 is a plan view thereof.

Here, the vertical tilt angle θ _A of the projector is as shown in FIG.
Is the angle (first angle) formed by the optical axis X of the projector 2 and the horizontal plane (floor surface). Screen horizontal tilt angle θ
_H is the amount of deviation (second angle) from the right angle of the angle formed by the optical axis X of the projector 2 and the display surface of the screen 1 as shown in FIG. What is the screen vertical tilt angle θ _V ?
Is an angle (third angle) formed between the display surface of the screen 1 and the vertical line.

In order to reduce the projection distortion of the projection display device, such a screen vertical tilt angle θ
_V , screen horizontal tilt angle θ _H , and projector vertical tilt angle θ _A must be measured respectively. However, actual measurement of these tilt angles is a very laborious work, and it may be difficult in some cases. For example, when the screen 1 is installed in a place difficult to approach or in a dangerous place, it is difficult to actually measure the screen vertical tilt angle θ _V and the screen horizontal tilt angle θ _H. In addition, if the measuring device cannot be fixed to the screen 1, accurate measurement cannot be performed, so the screen 1 must be solid. Therefore, there is a problem that the material of the screen 1 and the installation place are also limited.

Further, every time the screen 1 and the projector 2 are installed, the tilt angle θ of the screen 1 and the projector 2 must be read using a goniometer, and the value must be input to the distortion correction calculation circuit 7. At this time, a measurement error and an input error occurred. There is also a problem that skill is required to perform correct measurement. Further, it takes a lot of time to measure the tilt angle θ and it is difficult to measure the tilt angle θ, so that there is a drawback that it is difficult to install the projector 2 substantially outside the front of the screen 1.

The present invention has been made in view of the above-mentioned conventional problems, and there are few restrictions on the material and installation place of the screen of the projection type display device, and even an unskilled person can adjust the projection distortion. It is an object of the present invention to realize a projection distortion correction method for a projection display.

[0010]

SUMMARY OF THE INVENTION The present invention is a projection display device having a distortion correction arithmetic circuit for converting an input image and projecting the input image on a screen by using a projector. A first angle that is an angle formed by the optical axis and a predetermined reference plane, a second angle that indicates an inclination of the screen with respect to the optical axis of the projector, and a third angle that is an angle formed by a line orthogonal to the screen and the reference plane. When calculating, the reference calibration pattern is displayed on the screen, and the mapping conversion coefficient of the distortion correction calculation circuit is calculated so that the reference calibration patterns for the first to third angles calculation have the prescribed shape, and the distortion correction calculation circuit calculates. Using the set mapping conversion coefficient, the first to third angles are calculated, and the input image is mapped and converted using the mapping conversion coefficient corresponding to the first to third angles. The figure distortion of It is an feature.

[0011]

According to the present invention having such a feature, the reference calibrated figure is displayed on the screen in the projection type display device provided with the distortion correction arithmetic circuit for converting the input image. Then, the mapping conversion coefficient of the distortion correction calculation circuit is calculated so that the reference calibration pattern has a prescribed shape on the screen. Then, using the calculated mapping conversion coefficient, the first relationship indicating the positional relationship among the optical axis of the projector, the reference plane, and the screen is displayed.
~ Calculate a third angle value. The mapping conversion coefficient of the distortion correction calculation circuit is fixed using the measured angle value, and the mapping conversion of the input image is performed to correct the visual distortion of the screen. By doing so, even when the screen is installed at a high place, the first to third angles are automatically measured and the image distortion is automatically corrected.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A projection distortion correction method for a projection display according to an embodiment of the present invention will be described with reference to the drawings and mathematical formulas. Here, as a projection display device,
A liquid crystal projection type will be described. FIG. 1 is an overall perspective view showing the configuration of a projection display device according to an embodiment of the present invention. In the figure, the projection display device is composed of a screen 1 and a projector 2, and the projector 2
Also, it includes the projection lens 3, the liquid crystal panel 4, the backlight unit 5, and the liquid crystal panel drive circuit 6, which is the same as the conventional example, and the description thereof will be omitted.

Unlike the conventional example, a straight line drawing angle calculation unit 10 is connected to the projector 2 via a cable. The straight line drawing angle calculation unit 10 includes a straight line drawing angle adjustment unit 11,
For viewing the various test patterns projected on the screen 1, the projection display device user measures the projector vertical tilt angle θ _A , the screen horizontal tilt angle θ _H , and the screen vertical tilt angle θ _V , respectively. Is the operation unit of.

FIG. 2 is a block diagram showing a configuration example of the distortion correction arithmetic circuit 12. In the figure, an A / D converter 13 is a converter for converting an input video signal into a digital signal, and its output is given to the frame memory 14. The frame memory 14 is a circuit for writing and holding a 1-frame video signal input from the input port W. The read signal is output to the D / A converter 15 via the output port R.

The address counter 16 has a clock of the digital video signal, a vertical synchronizing signal Vd and a horizontal synchronizing signal Hd.
To generate an address signal of the mapping RAM 17. The mapping RAM 17 is a circuit that converts the read address of the video data stored in the frame memory 14. That is, the mapping RAM 17 inputs the address of the pixel position associated with the distortion correction via the input port A, converts this address into the address before correction, and outputs it from the output port R, and has the function of a conversion table. is doing.

The mapping RAM writing controller 18 inputs the projector vertical tilt angle θ _A , the screen horizontal tilt angle θ _H , and the screen vertical tilt angle θ _{V, respectively,} and performs mapping R
A circuit for registering address conversion data in AM17,
When registering or updating conversion data, the mapping RAM 1
Input port A of 7 and write port W
Give the translated address to.

A method for correcting the projection distortion of the liquid crystal projection display having the above structure will be described. [Measurement of tilt angle] FIG. 3 is an explanatory diagram showing a state in which a test pattern (reference calibration pattern) for measuring the tilt angle is displayed on the screen 1. FIG. 4 is a flow chart showing the operation procedure of measuring the tilt angle. When the operation is started in FIG. 4, during the angle measurement, as shown in FIG. 3, the straight line drawing angle calculation unit 10 simultaneously outputs the test patterns of two horizontal lines H1 and H2 and one vertical line V1. In step 21, such a linear image is first formed on the liquid crystal panel 4, and the enlarged image is projected on the screen 1 through the projection lens 3. In this case, the screen 1 is adjusted so that the projector vertical tilt angle θ _A , the screen horizontal tilt angle θ _H , and the screen vertical tilt angle θ _V are 0 degrees, respectively.
And if the projector 2 is installed, horizontal lines H1, H
2 is projected in parallel with the horizontal axis y of the screen 1, and the vertical line V1 is also projected in parallel with the vertical axis z of the screen 1. Therefore, even a viewer who is far from the screen 1
I feel that these lines are parallel to the horizontal axis y and the vertical axis z, respectively. In this case, no distortion correction is needed.

Next, it is assumed that the screen 1 and the projector 2 are installed in a state where the projector vertical tilt angle θ _A , the screen horizontal tilt angle θ _H , and the screen vertical tilt angle θ _V are not 0 degrees, respectively. First, it is assumed that the viewer sees the line H1 projected on the screen 1 from the viewer's position and feels that the line H1 is inclined with respect to the y-axis of the screen 1. This line H1
Is displayed in parallel with the y-axis on the liquid crystal panel 4.
Therefore, in step 22, the straight line drawing angle adjusting unit 11 is operated to adjust the inclination of the horizontal line H1 of the screen 1 to a position where it feels horizontal (parallel to the y-axis). Any two points P ₁ and P ₂ on the line H1 of the liquid crystal panel 4 at this time
Read the coordinates of and read the values of (yp ₁ , zp ₁ ), (yp ₂ ,
zp ₂ ).

Next, in step 23, the straight line drawing angle calculation unit 10 outputs the horizontal lines H1 and H2 and the vertical line V1 on the liquid crystal panel 4. Then, in step 24, the line drawing angle adjusting unit 11 is operated to operate the line H on the screen 1.
Adjust the tilt until you feel 2 is horizontal. When it becomes horizontal, the coordinates of any two points P ₃ and P ₄ on the line H2 of the liquid crystal panel 4 are read, and their values are (yp ₃ , z
p ₃ ) and (yp ₄ , zp ₄ ).

In the next step 25, the straight line drawing angle calculation unit 10 outputs horizontal lines H1 and H2 and a vertical line V1 which are straight line images to the liquid crystal panel 4. And step 2
6, the linear drawing angle adjusting unit 11 is operated to adjust the inclination of the vertical line V1 of the screen 1 to a position where the vertical line V1 is felt to be vertical. At this time, the coordinates of arbitrary two points P ₅ and P ₆ on the line V1 of the liquid crystal panel 4 are read, and their values are (y
Let p ₅ , zp ₅ ) and (yp ₆ , zp ₆ ).

When the projection of the test pattern is completed in this way, the process proceeds to step 27, where the straight line drawing angle calculation unit 1
0 calculates the projector vertical tilt angle θ _A and the screen horizontal tilt angle θ _H.

Here, the constants used in the following calculations are set as follows. L: Projection distance m: Magnification ratio w: Panel horizontal 1-view angle length h: Panel vertical 1-view angle length ky: Horizontal axis shift amount [view angle] kz: Vertical axis shift amount [view angle]

Next, the coordinate values of the six points P _{1 to} P ₆ obtained in steps 22, 24 and ₂₆ , P ₁ (yp ₁ , zp ₁ ), P ₂ (yp ₂ , zp ₂ ) P ₃ (yp ₃ , Zp ₃ ), P ₄ (yp ₄ , zp ₄ ) P ₅ (yp ₅ , zp ₅ ), P ₆ (yp ₆ , zp ₆ ) using the following equations (1) to (12) To do.

That is, the first conversion coordinates for the points P _{1 to} P ₆ are (Yp ₁ , Zp ₁ ), (Yp ₂ , Zp ₂ ) (Yp ₃ , Zp ₃ ), (Yp ₄ , Zp ₄ ) (Yp ₅ , Zp ₅ ), (Yp ₆ , Zp ₆ ), the coordinate value for each point is named the first mapping conversion coefficient, and the value is calculated.

[Equation 1]

[Equation 2]

[Equation 3]

[Equation 4]

[Equation 5]

[Equation 6]

Next, using the first mapping transformation coefficient obtained by the equations (1) to (12), the second mapping transformation coefficient defined by the following equations (13) to (18) is calculated. Ap ₁ , Bp ₁ , Cp ₁ Ap ₂ , Bp ₂ , Cp ₂

[Equation 7]

[Equation 8] Then, using the obtained second mapping conversion coefficient, the calculation of the following expression (19) is performed.

[Equation 9]

Then, using the conversion value W and the projection distance L obtained by the expression (19), the conversion value r of the following expression (20) is calculated.

[Equation 10]

Then, the converted value r obtained by the equation (20),
Using the projection distance L, the conversion value p of the following equation (21) is calculated.

[Equation 11]

Now, the conversion values r, p, obtained by the equation (20),
Using the projection distance L, the projector vertical tilt angle θ _A is calculated from the following equation (22) or equation (23).

[Equation 12]

Next, for the calculation of the screen horizontal tilt angle θ _H , the conversion values r, obtained in (20) and (21)
p, projection distance L, conversion coordinates (Yp ₁ ,
Using Zp ₁ ) and (Yp ₂ , Zp ₂ ), tan θ _H is calculated from the following equation (24).

[Equation 13] Therefore, by solving θ _H satisfying the equation (24), the screen horizontal tilt angle θ _H can be obtained.

Next, in step 28, the screen vertical tilt angle θ _V is calculated. That is, the conversion coordinates (Yp ₅ , Zp ₅ ) of the vertical line V1 obtained by the equations (9) to (12),
(Yp ₆ , Zp ₆ ) and si obtained from equations (22) and (23)
Using n θ _A , cos θ _A , and the projection distance L, the following formulas (25) to (28) are calculated.

[Equation 14]

[Equation 15]

Using the second transformed coordinates (y ₁ , z ₁ ) and (y ₂ , z ₂ ) obtained by the equations (25) to (28), the following equation (29) is calculated.

[Equation 16]

Since the value of tan θ _V can be obtained from the equation (29), the screen vertical tilt angle θ _V is calculated from this value.

Next, in step 29, the projector vertical tilt angle θ _A , the screen horizontal tilt angle θ _H , and the screen vertical tilt angle θ _V obtained above are displayed on the display unit as necessary, and these data are displayed. To the distortion correction calculation circuit 12. In step 30, the distortion correction calculation circuit 12 inputs the projector vertical tilt angle θ _A and the screen horizontal tilt angle θ.
Corrects the projection distortion based on _H and the screen vertical tilt angle θ _V.

[Flow of Video Signal] Referring to FIG. 1, the video signal is input to the distortion correction calculation circuit 12. FIG. 5 is an explanatory diagram showing the operation principle of the distortion correction calculation circuit 12. In the figure, the coordinates A, B, C, D indicate the positions of the four corners in the frame in the original video signal input via the A / D converter 13. The coordinates A ', B', C ', D'
Are the coordinates A, B, stored in the mapping RAM 17,
The read address positions of pixel data in C and D are shown. For example, the address of coordinate A is (1H,
500), and the address of coordinate A'is (100 H, 350). When the distortion correction calculation circuit 12 generates pixel data of one frame after the distortion correction calculation is performed, the address counter 16 sequentially generates addresses of one frame and outputs, for example, the address (100 H, 350). At this time, the mapping RAM 17 outputs the data (1H, 500) as an address to the frame memory 14. Therefore, the frame memory 14 reads the pixel data of the address (1H, 500) and outputs it to the liquid crystal panel 4 via the D / A converter 15.

By the above operation, the coordinates B ',
Even when the pixels of C ′ and D ′ are read out, the frame memory 14
The pixel data of the coordinates B, C, and D stored in is read, and a deformed image is formed on the liquid crystal panel 4 as a difference in light transmittance. The formed image is converted into a light beam of the image by the light beam emitted from the backlight unit 5, and the image is enlarged and projected by the projection lens 3, and the screen 1
The image is displayed on. In this way, even if the normal line of the screen 1 and the optical axis of the projector 2 are not parallel, the viewer can see an image with a natural feeling. The image displayed on the screen 1 looks distorted when viewed from the normal direction of the screen 1. However, when viewed from the adjustment place, in addition to the outer diameter shape of the screen 1, a person psychologically determines this image as a natural shape.

If a self-luminous device such as a CRT projection tube, an EL panel or a plasma display panel is used instead of the liquid crystal panel 4, the backlight unit 5 is not necessary. Also, when an optical display device (light valve) other than the liquid crystal panel 4 is used, the distortion can be similarly corrected. Furthermore, the shape of the screen, the shape of the figure projected on the screen, the method of forming the original figure, and the angle to be obtained are not limited to the examples described above.

[0037]

As described above, according to the present invention, the reference calibration pattern of the screen is operated on the input image forming surface so as to have a prescribed shape, and the first angle of the projector and the screen are indirectly adjusted. The second and third angles of can be measured. This eliminates the need to measure the tilt angle of the screen and projector using a goniometer, and can easily handle the case where the tilt angle is difficult to measure, such as when the screen is installed at a high place. The amount is small and safe measurement work can be performed. In addition, the reading error and the input error of the scale of the goniometer are eliminated, and the image distortion is automatically corrected.

[Brief description of drawings]

FIG. 1 is an external perspective view of a projection display device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a distortion correction calculation circuit used in the projection display apparatus of this embodiment.

FIG. 3 is an example of a test pattern used in the projection distortion correction method for a projection display according to the present invention.

FIG. 4 is a flowchart showing a procedure of a projection distortion correction method in this embodiment.

FIG. 5 is an explanatory diagram showing an operation principle of the distortion correction arithmetic circuit of the present embodiment.

FIG. 6 is an external perspective view of a conventional liquid crystal projection display.

FIG. 7 is a side view showing a positional relationship between a projector and a screen in a projection display device.

FIG. 8 is a plan view showing a positional relationship between a projector and a screen in a projection display device.

[Explanation of symbols]

 1 Screen 2 Projector 3 Projection Lens 4 Liquid Crystal Panel 5 Backlight Unit 6 Liquid Crystal Panel Drive Circuit 10 Straight Line Drawing Angle Calculation Section 11 Straight Line Drawing Angle Adjustment Section 12 Distortion Correction Calculation Circuit 13 A / D Converter 14 Frame Memory 15 D / A Converter 16 Address counter 17 Mapping RAM 18 Mapping RAM write controller

Claims (11)

[Claims] 1. A projection display apparatus having a distortion correction arithmetic circuit for mapping an input image and projecting the input image on a screen using a projector, comprising: an optical axis of the projector and a predetermined reference plane. When determining a first angle that is an angle formed, a second angle that indicates the inclination of the screen with respect to the optical axis of the projector, and a third angle that is an angle formed by the screen and a line orthogonal to the reference plane, A reference calibration figure is displayed on the top, and the mapping conversion coefficient of the distortion correction computation circuit is calculated so that the first to third reference calibration figures for angle calculation have a prescribed shape, and the mapping correction coefficient is set by the distortion correction computation circuit. The first to third angles are calculated by using the mapping conversion coefficient, and the input image is mapped and converted using the mapping conversion coefficient corresponding to the first to third angles, and the visual sense on the screen is obtained. upper Projection distortion correction method of a projection type display and corrects the Katachiibitsu. 2. The reference calibration pattern includes a plurality of horizontal lines parallel to each other on the screen,
2. The projection distortion correction method for a projection display according to claim 1, wherein the horizontal line and the vertical line are orthogonal to each other. 3. The projection distortion correction method for a projection display according to claim 1, wherein the predetermined reference plane is the ground. 4. The projection distortion correction method for a projection display according to claim 1, wherein the predetermined reference plane is a ceiling surface. 5. The projection distortion correction method for a projection display according to claim 1, wherein the projector forms an input image with a light valve. 6. The projection distortion correction method for a projection display according to claim 1, wherein the projector forms an input image with a liquid crystal panel. 7. The projection distortion correction method for a projection display according to claim 1, wherein the projector forms an input image by a self-luminous device. 8. The projection distortion correction method for a projection display according to claim 1, wherein the projector forms an input image by a CRT. 9. The projection distortion correction method for a projection display according to claim 1, wherein a surface of the projector on which a figure is formed is a flat surface. 10. The projection distortion correction method for a projection display according to claim 1, wherein the screen is a flat surface. 11. The projection distortion correction method for a projection display according to claim 1, wherein the screen has a polarization characteristic.