JP2000122617A - Trapezoidal distortion correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically and surely correct a trapezoidal distortion generated on a projection picture plane without requiring a troublesome correction operation by a user. SOLUTION: A first and a second distance sensors 30, 31 installed plurally on different positions on the front of a liquid crystal projector body 1 detect the distances between the body 1 and a screen 9, respectively. A control microcomputer 32 calculates the angle of inclination of the body 1 relative to the screen 9 based on the result of detection, and controls and image processing circuit 11A capable of thinning adjustment of the pixel data of each line based on the result of calculation, so that the projection image light of a liquid crystal panel 5 will form a trapezoidal distortion shape reverse to the trapezoidal distortion shape of a projection picture plane caused by the angle of inclination of the body 1. Hereby, the trapezoidal distortion generated on the projection picture plane can be automatically corrected without requiring a troublesome operation by a user.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a trapezoidal distortion correction device for correcting a trapezoidal distortion generated in a projected image due to an installation state of a front projection type liquid crystal projector, and does not require a troublesome manual operation by a special user. The present invention relates to a trapezoidal distortion correction device capable of automatically and optimally correcting keystone distortion.

[0002]

2. Description of the Related Art In recent years, a liquid crystal projector using a liquid crystal panel has been actively developed with a demand for a small-sized and lightweight display device having a large screen. Liquid crystal projectors are also expected to be used for high-definition televisions because they can easily be made larger.

[0003] Among them, a front projection type liquid crystal projector is small and lightweight, and can be easily installed and used.
In addition, since it is not so expensive in terms of cost, it is popular with users in recent years and widely used, and demand for the future is sufficiently expected.

[0004] Therefore, in order to satisfy such demands of the user, a front projection type liquid crystal projector not only obtains an excellent projection image without deteriorating the quality of the projection image, but also temporarily obtains the projection image. It is necessary to have a function that can immediately correct even when distortion or the like occurs, and it is desirable that the correction performance be high in accuracy.

FIG. 8 shows an example of a conventional general front projection type liquid crystal projector having such a correction function.

As shown in FIG. 8, the liquid crystal projector is provided with an input terminal 1a for inputting a video signal of a video source to be displayed, and the input video signal supplied through the input terminal 1a It is supplied to a video circuit 11 as a main circuit provided inside.

In order to accurately reproduce an image based on an input image signal, the image circuit 11 amplifies the input image signal to a voltage necessary for driving the liquid crystal panel 5 or extends the life of the liquid crystal. It mainly includes a liquid crystal drive circuit having a function of performing an AC drive for processing, a processing circuit necessary for correcting trapezoidal distortion, and the like. In other words, the video circuit 11 performs signal processing necessary for displaying an image based on the input video signal on the display surface of the liquid crystal panel 5 used in the liquid crystal projector, thereby performing the signal processing according to the input video signal. Liquid crystal panel 5
Give to. As a result, a video screen based on the input video signal is displayed on the display surface of the liquid crystal panel 5.

On the other hand, the visible light 4 emitted from the light source 3 using a reflector or the like passes through the display surface of the liquid crystal panel 5,
The transmitted light 7 of the transmitted liquid crystal panel 5 is narrowed down by the condenser lens 6 and is enlarged and projected by the projection lens 2 to be enlarged and displayed on the screen 9. As a result, a video screen displayed on the liquid crystal panel is formed on the screen 9 as the projection screen 10.

In general, such a front-projection type liquid crystal projector often allows a viewer to view the projection screen from behind the main body 1, so that the field of view of the viewer is controlled by the main body 1.
In some cases, it is installed so that it is not obstructed. That is, the angle of the main body 1 is set so that the projection screen is positioned above the main body 1.
Will be installed. However, in such a case, for example, as shown in FIG. 9, the projection screen 10 having a distortion called trapezoidal distortion (also referred to as keystone distortion) is generated due to a deviation of the projection angle due to the installation state of the liquid crystal projector main body 1. Will be formed.

There are generally two methods for correcting such trapezoidal distortion. One is a correction method for electrically correcting trapezoidal distortion, and the other is an optically correcting trapezoidal distortion. Correction method.

A method for electrically correcting trapezoidal distortion is to display an image screen having a trapezoidal distortion opposite to the projected image on the display surface of the liquid crystal panel 5 by the image circuit 11 and enlarge and project the image screen. This is a method for correcting the trapezoidal distortion.

Another method of optically correcting trapezoidal distortion is to use a condenser lens 6 in the liquid crystal projector body 1.
This is a method for correcting the trapezoidal distortion of the projection screen by adjusting the inclination of.

Alternatively, trapezoidal distortion can be corrected by adopting a structure in which the liquid crystal panel 5 is tilted instead of tilting the condenser lens 6.

However, in the above-described conventional electric and optical trapezoidal distortion correction methods, the correction is performed by a user's operation. And the like, there is a problem that the operation content is complicated and cannot be easily performed.

[0015]

As described above, in the conventional trapezoidal distortion correction method, a trapezoidal distortion opposite to the projection screen is generated in the input video signal itself or in the transmitted light of the liquid crystal panel electrically or optically. Therefore, correction was made to reduce the trapezoidal distortion that occurred on the projection screen.
In each case, the correction is performed by the user's operation. Therefore, in order to surely correct the trapezoidal distortion, delicate level adjustment is required, so that the operation content is complicated and can be easily performed. There was no problem.

Accordingly, the present invention has been made in view of the above problems, and does not require a complicated correction operation by a user, and can automatically and reliably correct a trapezoidal distortion generated on a projection screen. It is intended to provide a distortion correction device.

[0017]

According to a first aspect of the present invention, there is provided a trapezoidal distortion correcting apparatus for projecting an image formed on a liquid crystal panel surface based on an input video signal by irradiation light from a light source and projecting the image. In a liquid crystal display device for enlarging and displaying image light on a screen via an optical system means, a plurality of image lights are provided at different positions on the front surface of the liquid crystal display device main body, and the distance between the liquid crystal display device main body and the screen is detected, A distance detection unit that outputs a detection result; and a processing circuit that performs processing for forming an image based on the input video signal on the liquid crystal panel surface, and a memory that stores pixel data corresponding to the input video signal. By changing the timing of writing and reading pixel data of the memory for each line, it is possible to adjust the thinning of pixel data for each line. A processing circuit that calculates an inclination angle of the liquid crystal display device main body with respect to the screen based on a detection result from the distance detection unit, and, based on the calculation result, a projection screen of the liquid crystal display device main body caused by the inclination angle. Correction control means for automatically controlling the video processing circuit so as to correct trapezoidal distortion.

According to the present invention, the distance between the liquid crystal display device main body and the screen is detected by a plurality of distance detecting means provided at different positions on the front surface of the liquid crystal display device main body. The video processing circuit is a processing circuit that performs processing for forming an image based on the input video signal on the liquid crystal panel surface, and includes a memory that stores pixel data corresponding to the input video signal. By changing the timing of writing and reading data for each line, thinning adjustment of pixel data for each line can be performed. When trapezoidal distortion occurs, the correction control means calculates the tilt angle of the liquid crystal display device body with respect to the screen based on the detection result from the distance detection means, and based on the calculation result, the tilt angle of the liquid crystal display device body. Automatically controls the video processing circuit so as to correct the trapezoidal distortion of the projection screen caused by the image processing. Thereby, since the projected image light of the liquid crystal panel has a trapezoidal distortion shape opposite to the trapezoidal distortion shape of the projection screen, the trapezoidal distortion can be reduced as a result, and the trapezoidal distortion correction is automatically performed. It is possible to do.

According to a second aspect of the present invention, there is provided a trapezoidal distortion correcting apparatus for projecting an image formed on a liquid crystal panel surface based on an input video signal by irradiation light from a light source, and projecting the projected image light into an optical system. In a liquid crystal display device for enlarging and displaying on a screen via a means, a plurality of liquid crystal display devices are provided at different positions on the front surface of the liquid crystal display device main body, and each detects a distance between the liquid crystal display device main body and the screen and outputs a detection result. A lens for condensing projected image light from the liquid crystal panel and irradiating it to a screen via a projection lens, and a driving means for freely changing an inclination angle of the lens itself; A condenser lens, an angle adjusting unit that can control the driving unit of the condenser lens, and a screen for the screen based on a detection result from the distance detecting unit. A correction control for calculating an inclination angle of the liquid crystal display device main body and automatically controlling the angle adjusting means based on the calculation result so as to correct a trapezoidal distortion of a projection screen caused by the inclination angle of the liquid crystal display device main body. Means.

According to this invention, the correction control means controls the angle adjusting means to change the inclination angle of the condenser lens, so that the projection screen has a trapezoidal distortion shape opposite to the trapezoidal distortion shape. The projection image light of the liquid crystal panel is obtained. Thereby, the same effect as the above-described invention can be obtained.

According to a third aspect of the present invention, there is provided a trapezoidal distortion correction apparatus for projecting an image formed on a liquid crystal panel surface based on an input video signal by irradiation light from a light source, and projecting the projected image light into an optical system. In a liquid crystal display device for enlarging and displaying on a screen via a means, a plurality of liquid crystal display devices are provided at different positions on the front surface of the liquid crystal display device main body, and each detects a distance between the liquid crystal display device main body and the screen and outputs a detection result. A distance detecting unit, a liquid crystal panel including a driving unit that freely changes an inclination angle of the liquid crystal panel itself, an angle adjusting unit that can control the driving unit of the liquid crystal panel,
An inclination angle of the liquid crystal display device main body with respect to the screen is calculated based on a detection result from the distance detection means, and based on the calculation result, a trapezoidal distortion of a projection screen caused by the inclination angle of the liquid crystal display device main body is corrected. Correction control means for automatically controlling the angle adjustment means.

According to the present invention, the correction control means controls the angle adjusting means to change the inclination angle of the liquid crystal panel, so that the projection screen has a trapezoidal distortion shape opposite to the trapezoidal distortion shape. The projection image light of the liquid crystal panel is obtained. Thereby, the same effect as the above-described invention can be obtained.

[0023]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a trapezoidal distortion correction apparatus according to the present invention, and showing a configuration example of a front projection type liquid crystal projector configured by incorporating the apparatus.

In this embodiment, in order to automatically correct the trapezoidal distortion of the projection screen caused by the installation state of the front projection type liquid crystal projector, the liquid crystal projector 1
First and second distance sensors 3 as distance detecting means for respectively detecting the distance to the screen 9 above and below the front side of
0, 31 and the first and second distance sensors 3
Based on the detection results obtained by 0 and 31, the processing in the video circuit used in the prior art is performed to achieve the object.

As a specific overall configuration, a front projection type liquid crystal projector incorporating the trapezoidal distortion correction device of the present embodiment is, as shown in FIG. 1, composed of the first and second distance sensors 30, 31, It is characterized in that the control microcomputer 32 and the like are provided.

That is, as shown in FIG. 1, the liquid crystal projector is provided with an input terminal 1a for inputting a video signal of a video source to be displayed, and an input video signal supplied via the input terminal 1a is: It is supplied to a video circuit 11A as a main circuit provided inside the main body 1.

In order to accurately reproduce an image based on an input video signal, the video circuit 11A normally amplifies the input video signal to a voltage required to drive the liquid crystal panel 5 or extends the life of the liquid crystal. It mainly includes a liquid crystal drive circuit having a function of performing an AC drive for processing, a processing circuit necessary for correcting trapezoidal distortion, and the like. That is, the video circuit 11A performs signal processing necessary for displaying an image based on the input video signal on the display surface of the liquid crystal panel 5 used in the liquid crystal projector, by applying the signal processing to the input video signal. A corresponding panel drive signal is obtained and given to the liquid crystal panel 5. As a result, a video screen based on the input video signal is displayed on the display surface of the liquid crystal panel 5. When trapezoidal distortion occurs in the projection screen 10, the video processing circuit 11 </ b> A performs a process for generating a trapezoidal distortion reverse to that of the projection screen 10 on the input video signal, thereby obtaining the projection screen 10. By applying a panel drive signal to the liquid crystal panel 5 to reduce the trapezoidal distortion, a corrected image on the display surface of the liquid crystal panel 5 on which a process necessary to correct the trapezoidal distortion generated on the projection screen 10 is performed. The screen is displayed.

On the other hand, the visible light 4 emitted from the light source 3 using a reflector or the like passes through the display surface of the liquid crystal panel 5,
The transmitted light 7 of the transmitted liquid crystal panel 5 is narrowed down by the condenser lens 6 and is enlarged and projected by the projection lens 2 to be enlarged and displayed on the screen 9. As a result, a video screen displayed on the liquid crystal panel is formed on the screen 9 as the projection screen 10.

However, as described in the prior art, when the viewer views the projection screen from behind the main body 1, the main body 1 does not block the field of view of the viewer.
Is installed, a trapezoidal distortion is generated on the projection screen due to a shift of the projection angle due to the installation state of the liquid crystal projector main body 1, and the display image becomes difficult to see.

Therefore, in the present embodiment, as means for correcting such trapezoidal distortion, the video circuit 11A
(Substantially the same configuration as the video circuit 11 in FIG. 7),
A correction method is adopted in which trapezoidal distortion opposite to that of the projection screen is generated in the light emitted from the projection lens 2 in accordance with the degree of the trapezoidal distortion, so that the trapezoidal distortion of the projection screen is reduced.

In the correction method using the video circuit 11A, a video screen having a trapezoidal distortion is displayed on the display surface of the liquid crystal panel 5 by the video circuit 11A shown in FIG. 1, and the projected image is enlarged and projected. This is a method for correcting trapezoidal distortion. That is, by adjusting the processing by the video circuit 11A, the trapezoidal distortion of the projection screen is corrected as a result.

Specifically, as shown in FIG. 3, a black signal (no video signal) is displayed at the start and end of horizontal scanning every one or several lines, and as the vertical scanning progresses, the angle of trapezoidal distortion is increased. , The black signal portion is reduced at a fixed rate and displayed. For example, if the liquid crystal panel 5 is composed of M pixels (horizontal) × N pixels (vertical) and scans from the lower right to the left and from the bottom to the top of the drawing, one line at the start of vertical scanning In this example, a black signal portion of q pixels is displayed at the start and end of horizontal scanning, and video data of M-2q pixels obtained by subtracting data of M pixels by 2q pixels is displayed between black signal portions. . In the L line where the vertical scanning has advanced several lines, a non-signal portion of p pixels less than q pixels is displayed. The p pixels in this case can be represented by the relational expression of p = q (NL) / N pixels. The video display portion displays video data of M-2p pixels subtracted by 2p pixels. Then, as shown in the figure, the black signal portion is not displayed on the N-line of the last vertical scanning line. Thus, by displaying a movie screen having a trapezoidal distortion on the display surface of the liquid crystal panel 5, it is possible to correct the trapezoidal distortion of the projection screen.

FIG. 4 shows a specific configuration of the video circuit 11A necessary to control the display operation of the liquid crystal panel 5 as described above. Further, the control operation of the video circuit 11A in FIG. 1 will be described. A timing chart is shown in FIG. 5, and a specific operation will be described below.

In the video circuit 11A, the video signal input through the input terminal 11a as shown in FIG.
It is supplied to the D converter 11b, and the A / D converter 11b performs a sampling process using a sample clock (see FIG. 5A) from the control signal generation circuit 11d, thereby forming M × N pixels. Is converted into digitized video data (also referred to as pixel data). afterwards,
This video data is written to the memory 11c at the timing based on the write control signal at the same timing as the sampling clock (FIG. 5B,
(See (d) and (f)).

In the next field, the pixel data written in each line is read out at a timing different from the write control signal based on a read control signal from the control signal generation circuit 11d, and is read out by the D / A converter 11e. Supplied to That is, the control signal generation circuit 11d can control writing and reading of video data to and from the memory, and can freely thin out video data of each line by changing these timings.

The D / A converter 11e converts the analog signal into an analog signal again at the timing of the sample clock from the control signal generating circuit 11d and returns the analog signal to the liquid crystal drive circuit 11f. The liquid crystal drive circuit 11f amplifies the input video signal to a voltage necessary for driving the liquid crystal panel 5, and then performs a process such as a polarity inversion process for performing AC driving, thereby obtaining a panel corresponding to the video signal. When the drive signal is generated and supplied to the liquid crystal panel 5, an image based on the input image signal is displayed on the display surface of the liquid crystal panel 5.

At this time, the control signal generation circuit 11d
In the line, control is performed so that a black signal is displayed without reading 1 to q sample clocks (pixels) from the start of scanning. Then, the first pixel data 1 is read out on the (q + 1) -th pixel, and data of M−2q pixels obtained by thinning out 2q pixels until the last pixel data M is read on the (M−q) -th pixel is read out. After that, control is performed so that a black signal is displayed without reading q pixels again (see FIG. 5C).

In the L line where the vertical scanning has progressed, similarly, control is performed so that a black signal is displayed without reading out 1 to p sample clocks (pixels) from the start of scanning (FIG. 5C).
reference). Then, control is performed such that the first pixel data is read out at the (p + 1) -th pixel, and data of M-2p pixels obtained by thinning out 2p pixels until the last pixel data M is read out at the (M−p) -th sample clock is read. At the subsequent timing, the control signal generation circuit 11d controls so as to display a black signal without reading p pixels again (FIG. 5).
(E)).

In the last N lines of the vertical scanning, the no-signal portion is not displayed, and the M pieces of written data are read as they are and supplied to the liquid crystal panel 5, so that an image based on the read video data is displayed on the liquid crystal panel 5. Display on the display surface.

With the above-described control operation, the reverse trapezoidal distortion necessary for correcting the trapezoidal distortion generated on the projection screen is generated on the display surface of the liquid crystal panel.

However, automatic correction cannot be performed by the above-described correction processing of only the video circuit 11A.

Therefore, in the present embodiment, the first and second distance sensors 30 and 31 necessary for automatically performing the trapezoidal distortion correction processing by the video circuit 11A, and the second distance sensor 30 , 31, the inclination angle of the projection screen 10 of the screen 9 is calculated, and based on the calculation result, the display image of the liquid crystal panel having the trapezoidal distortion opposite to the trapezoidal distortion of the projection screen 10 is formed with high accuracy. For this purpose, a control microcomputer 32 for controlling the processing by the video circuit 11A is provided.

The operation of the trapezoidal distortion correction under the control of the control microcomputer 32 will be described with reference to FIG.

The first and second distance sensors 30, 3
Numerals 1 are provided on the front side of the projector body 1, that is, in the vertical direction on the side of the projection lens 2, respectively. These first and second distance sensors 30, 31 are:
For example, by emitting light and receiving the reflected light, the distances D1 and D2 between the front surface of the main body 1 and the screen 9 are measured, and the measurement results are provided to the control microcomputer 32 as electric signals. Note that the first and second distance sensors 30 and 31 are not limited to those using light, as long as they can obtain the respective distances.
You may comprise using another sensor.

The control microcomputer 32 is, for example, a control microcomputer for controlling the entire system of the liquid crystal projector.
When the measurement results from the first and second distance sensors 30 and 31 are supplied, processing by the video circuit 11A based on the supplied measurement results is performed to correct trapezoidal distortion generated on the projection screen 10. To control the adjustment.

For example, the control microcomputer 32 calculates the inclination angle θ between the main body 1 and the screen 9 from the measurement results from the first and second distance sensors 30 and 31, and based on the calculation result, the trapezoidal distortion. After calculating the shape, the processing by the video circuit 11A is controlled based on the result of the calculation so as to obtain a panel drive signal having a trapezoidal distortion opposite to the trapezoidal distortion of the projection screen 10. At this time, the control microcomputer 32 calculates the tilt angle, for example, as shown in FIG. 2, where the tilt angle between the main body 1 and the screen 9 is θ, and the vertical width of the normal projection screen 10 is d (each of the sensors 30, 3).
When the light of No. 1 is converted into the parallel light of the sensor, the parallel light of each sensor D1,
(Corresponding to the distance between D2), tan θ = d / (D1−D2) (Equation 1).

The control microcomputer 32 controls the video processing circuit 11A by transmitting a control signal for generating a reverse trapezoidal distortion based on the calculation processing result to a control signal generation circuit 11d in the video circuit 11A (see FIG. 4). ), The control signal generation circuit 11d responds to the control to change the timing of the read control signal for each line. Thus, by adjusting the pixel data for each line using the memory 11c (see FIG. 4) described with reference to FIGS. 3 to 5, the trapezoidal distortion shape generated on the projection screen 10 is reversed. It is possible to obtain a panel display screen having a trapezoidal distortion. As a result, the trapezoidal distortion of the projection screen 10 caused by the inclination angle between the main body 1 and the screen 9 can be automatically and reliably determined according to the generated shape. It becomes possible to correct.

Therefore, in the present embodiment, it is possible to automatically and reliably correct the trapezoidal distortion generated on the projection screen without performing a complicated operation by the user, and to achieve high quality with reduced trapezoidal distortion. It is possible to provide a high-performance front-projection liquid crystal projector capable of obtaining a liquid crystal projection image.

Next, another embodiment of the trapezoidal distortion correcting apparatus of the present invention will be described in detail with reference to FIG.

FIG. 6 is a block diagram showing a configuration example of a liquid crystal projector incorporating a trapezoidal distortion correction device according to another embodiment of the present invention.

In this embodiment, the trapezoidal distortion correction is performed automatically by applying the present invention to the correction method for optically correcting the trapezoidal distortion instead of the electrical trapezoidal distortion correction method in the above embodiment. The configuration is different from the above embodiment.

As a specific configuration, the first and second distance sensors 30 and 31 which are the features of the present invention, and the screen 9 based on the detection results obtained by these second distance sensors 30 and 31 are used. The inclination angle of the projection screen 10 is calculated,
Based on the calculation result, the transmitted light of the liquid crystal panel is
And a control microcomputer 32A for controlling the inclination angle of the condenser lens 6 so as to obtain a trapezoidal distortion opposite to the above trapezoidal distortion.

An angle adjusting device 2 serving as a main circuit shown in FIG.
0 controls the driving means (not shown) provided in the condenser lens 6 so that the condenser lens 6
It adjusts its own inclination. That is, the inclination of the condenser lens 6 is tilted, for example, as shown by a dashed line 21 in the drawing, so that a trapezoidal distortion opposite to the projection screen is generated in the transmitted light of the liquid crystal panel 5, and as a result, the projection screen To correct keystone distortion.

In the present embodiment, the first and second distance sensors 30 and 31 emit light in the same manner as in the above embodiment, in order to automatically perform the optical trapezoidal distortion correction. By receiving the reflected light, the distances D1 and D2 between the front surface of the main body 1 and the screen 9 are measured, and the measurement results are provided to the control microcomputer 32A as electric signals.

The control microcomputer 32A includes the first and second
The inclination angle between the main body 1 and the screen 9 is calculated from the measurement results from the distance sensors 30 and 31, and the shape of the trapezoidal distortion is calculated based on the calculation result. Is supplied to the angle adjustment device 20 such that the visible light of the projection screen 10 becomes trapezoidal distortion opposite to the trapezoidal distortion of the projection screen 10, and in response to this, the angle adjustment device 20 changes the inclination of the condenser lens 6 to, for example, a wavy line. 2
As shown in FIG. 1, the angle is adjusted and controlled.

As a result, the inclination of the condenser lens 6 is adjusted in accordance with the shape of the trapezoidal distortion, so that the transmitted light of the liquid crystal panel has a trapezoidal distortion opposite to the trapezoidal distortion generated on the projection screen 10. And as a result body 1
Trapezoidal distortion of the projection screen 10 resulting from the inclination angle θ between the screen and the screen 9 can be automatically and reliably corrected according to the shape of the generated projection screen.

The present invention can also be applied to other optical trapezoidal distortion correction methods. Such an embodiment will be described in detail with reference to FIG.

FIG. 7 is a block diagram showing a configuration example of a liquid crystal projector incorporating a trapezoidal distortion correction device according to another embodiment of the present invention.

This embodiment is almost the same as the optical trapezoidal distortion correction method described in the above embodiment.
Rather than controlling the inclination of the condenser lens to the optimum angle, the liquid crystal panel 5 itself is configured to perform the trapezoidal distortion correction automatically by adjusting and controlling the liquid crystal panel 5 to the optimum angle necessary for correcting the trapezoidal distortion. This is a point different from the above embodiment.

As a specific configuration, the first and second distance sensors 30 and 31, which are features of the present invention, and the screen 9 based on the detection results obtained by these second distance sensors 30 and 31. The inclination angle of the projection screen 10 is calculated,
Based on the calculation result, the transmitted light of the liquid crystal panel is
The liquid crystal panel 5 has a trapezoidal distortion opposite to the trapezoidal distortion of
And a control microcomputer 32B for controlling the inclination angle of the respective components.

An angle adjusting device 2 serving as a main circuit shown in FIG.
2 is a driving means (not shown) provided on the liquid crystal panel 5
Is controlled, the inclination of the liquid crystal panel 5 itself is adjusted. In other words, the inclination of the liquid crystal panel 5 is tilted, for example, as shown by a dashed line 23 in the figure, so that the transmission light of the liquid crystal panel 5 causes a trapezoidal distortion opposite to that of the projection screen. To correct keystone distortion.

In the present embodiment, the first and second distance sensors 3 are used to automatically perform the optical trapezoidal distortion correction.
In the same manner as in the above-described embodiment, the light-emitting devices 0 and 31 emit light and receive reflected light of the light.
The distances D1 and D2 between the front part of the screen and the screen 9 are measured,
The measurement result is given to the control microcomputer 32B as an electric signal.

The control microcomputer 32B is provided with the first and second
The inclination angle between the main body 1 and the screen 9 is calculated from the measurement results from the distance sensors 30 and 31, and the shape of the trapezoidal distortion is calculated based on the calculation result. Is supplied to the angle adjustment device 22 so that the visible light of the projection screen 10 has a trapezoidal distortion opposite to the trapezoidal distortion of the projection screen 10. As shown by a dashed line 23, the angle is adjusted and controlled.

As a result, the inclination of the liquid crystal panel 5 is adjusted in accordance with the shape of the trapezoidal distortion, so that the transmitted light of the liquid crystal panel has a trapezoidal distortion opposite to the trapezoidal distortion generated on the projection screen 10. As a result, the projection screen 10 resulting from the inclination angle θ between the main body 1 and the screen 9 is obtained.
Can be automatically and reliably corrected in accordance with the generated shape.

Therefore, according to the present embodiment, the same effects as those of the above embodiment can be obtained.

In each embodiment according to the present invention, the control microcomputers 32, 32A, and 32B control the first
Based on the calculation results from the second and third distance sensors 30 and 31, a calculation process is performed so that a trapezoidal distortion shape reverse to the trapezoidal distortion shape generated on the projection screen is obtained. It has been described that the trapezoidal distortion correction processing is performed by controlling the angle adjusting devices 20 and 22. For example, a table in which the shape data of the trapezoidal distortion corresponding to the inclination angle of the screen with respect to the main body is previously stored in each control microcomputer. When a memory or the like is provided and keystone distortion is corrected, the first memory is referred to by referring to the table memory.
And trapezoidal distortion shape data corresponding to the calculation results from the second distance sensors 30 and 31 are obtained, and a video circuit or an angle adjusting device is controlled based on the obtained trapezoidal distortion shape,
It may be configured to perform trapezoidal distortion correction.

[0067]

As described above, according to the present invention, it is possible to automatically and reliably correct the trapezoidal distortion generated on the projection screen without requiring a complicated correction operation by the user. As a result, it is possible to provide a high-performance front-projection liquid crystal projector capable of obtaining high-quality liquid crystal projection images with suppressed trapezoidal distortion.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an embodiment of a trapezoidal distortion correction apparatus according to the present invention, and illustrating an overall configuration of a liquid crystal projector in which the apparatus is incorporated.

FIG. 2 is an explanatory diagram for explaining a method of calculating an angle between a main body and a screen by a control microcomputer in FIG. 1;

FIG. 3 is an explanatory diagram for describing a correction method for electrically correcting keystone distortion.

FIG. 4 is a block diagram showing a configuration example of a video circuit for performing electric trapezoidal distortion correction.

5 is a timing chart for explaining control of writing and reading of video data to and from a memory by the video circuit shown in FIG. 4;

FIG. 6 is a block diagram showing a trapezoidal distortion correction apparatus according to another embodiment of the present invention, and showing a configuration of a liquid crystal projector when the apparatus is applied to an optical correction method.

FIG. 7 is a block diagram showing a trapezoidal distortion correction apparatus according to another embodiment of the present invention, and showing a configuration of a liquid crystal projector when the apparatus is applied to an optical correction method.

FIG. 8 is a block diagram showing a configuration of a general front projection type liquid crystal projector.

FIG. 9 is an explanatory diagram for explaining a state of occurrence of trapezoidal distortion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal projector main body, 2 ... Projection lens, 3 ... Light source, 4 ... Visible light, 5 ... Liquid crystal panel, 6 ... Condenser lens, 7 ... Panel transmitted light, 8 ... Optical axis, 9 ... Screen, 10 ... Projection screen, 11A: video circuit, 20, 22: angle adjusting device, 30: first distance sensor (distance detecting means), 31: second distance sensor (distance detecting means), 32, 32A, 32B: control microcomputer (control means) ).

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) JJ06 KK52

Claims (4)

[Claims] 1. A liquid crystal display for projecting an image formed on a liquid crystal panel surface formed based on an input video signal by irradiation light from a light source and enlarging and displaying the projected image light on a screen via an optical system means. In the apparatus, a plurality of distance detection means are provided at different positions on the front surface of the liquid crystal display device main body, each detect a distance between the liquid crystal display device main body and the screen, and output a detection result, and an image based on the input video signal. Is a processing circuit that performs processing for forming on the liquid crystal panel surface, comprising a memory that stores pixel data corresponding to an input video signal,
An image processing circuit capable of adjusting the thinning of pixel data for each line by changing the timing of writing and reading pixel data of the memory for each line, and the image processing circuit for the screen based on a detection result from the distance detecting means. Correction control means for calculating an inclination angle of the liquid crystal display device main body and automatically controlling the video processing circuit so as to correct trapezoidal distortion of a projection screen caused by the inclination angle of the liquid crystal display device main body based on the calculation result. A trapezoidal distortion correction device, comprising: 2. A liquid crystal display in which an image formed on a liquid crystal panel surface formed based on an input video signal is projected by light emitted from a light source, and the projected image light is enlarged and displayed on a screen via an optical system. In the device, a plurality of distance detection means are provided at different positions on the front surface of the liquid crystal display device main body, each detect a distance between the liquid crystal display device main body and the screen, and output a detection result, and a projection image from the liquid crystal panel A condenser lens for condensing light and irradiating it to a screen via a projection lens, the condenser lens including a driving unit for freely changing an inclination angle of the lens itself, and the driving unit for the condenser lens Angle adjusting means that can control the angle of inclination of the liquid crystal display device with respect to the screen based on the detection result from the distance detecting means. Correction control means for automatically controlling the angle adjustment means so as to correct trapezoidal distortion of the projection screen caused by the inclination angle of the liquid crystal display device body based on the calculation result. Distortion correction device. 3. A liquid crystal display in which an image formed on a liquid crystal panel surface formed based on an input video signal is projected by irradiation light from a light source, and the projected image light is enlarged and displayed on a screen via an optical system. In the apparatus, a plurality of distance detection means are provided at different positions on the front surface of the liquid crystal display device main body, each detect a distance between the liquid crystal display device main body and the screen, and output a detection result, and an inclination angle of the liquid crystal panel itself. A liquid crystal panel having driving means for freely changing the angle of the liquid crystal panel; an angle adjusting means capable of controlling the driving means of the liquid crystal panel; and a tilt of the liquid crystal display device body with respect to the screen based on a detection result from the distance detecting means. An angle is calculated, and based on the calculation result, the angle adjustment is performed so as to correct the trapezoidal distortion of the projection screen caused by the inclination angle of the liquid crystal display device main body. Keystone distortion correction apparatus characterized by comprising a correction control means for automatically controlling the means. 4. The correction control unit is configured to obtain, based on the calculation result, projection image light having a trapezoidal distortion shape opposite to a trapezoidal distortion shape of a projection screen caused by an inclination angle of the liquid crystal display device main body. 4. The trapezoidal distortion correction device according to claim 1, wherein the image processing circuit means or the angle adjustment means is controlled.