JPH08205061A - Display device - Google Patents

Abstract

(57) [Summary] [Object] To realize a projection image in a projection type display device, in which distortion due to oblique projection is eliminated and out-of-focus of the display image is removed. [Structure] The projection display device 1 obliquely projects onto a screen 2. The distortion of the projected image on the screen 2 caused at that time is previously corrected by the distortion correction circuit 3 for the input video signal 11 by image processing. As a result, a video with a correct shape can be displayed. On the other hand, the image display body 4 or the projection lens 5 of the projection display apparatus 1 is tilted by the rotation adjusting unit 6 by an angle corresponding to the tilt angle of the screen 2 with respect to the projection optical axis 10. As a result, the focus shift (image out-of-focus) caused by the oblique projection is removed.

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, and more particularly, when a screen is tilted with respect to a projection optical axis, in other words, when an image is projected obliquely onto the screen. Corrects image distortion caused by oblique projection and eliminates focus shift (image out-of-focus) due to the difference between each position on the screen and the projection device, as if projecting vertically to the screen. The present invention relates to a display device that realizes such a projected image.

[0002]

2. Description of the Related Art Conventionally, in a projection type display device, an image is displayed on an image display such as a cathode ray tube or a liquid crystal panel, and the display is projected as a radial projection light on a screen through a projection lens. At this time, the projection display device
The projected image is projected from the front or the rear of the screen, and a reflective screen or a transmissive diffusion screen is used for the screen depending on the difference between the front and the rear. When observing the display image on the screen, the observation angle changes depending on the observation position, but a screen having a wide viewing angle has been used so that the display image can be viewed as uniformly as possible from any position.

FIG. 6 is a diagram showing a display image when the projection optical axis 10 is projected so as to be perpendicular to the screen 2 using the above conventional display device. As shown in (a) of FIG. 6, the projection optical axis 10 of the projection type display device 1 in which the image display body and the projection lens are combined is set to be substantially perpendicular to the screen 2 and used. The radial projection light at this time spreads radially in a vertically and horizontally symmetrical manner as shown in (b-1) of FIG. 6, or spreads greatly to one side in the vertical direction as shown in (b-2) of FIG. , Projected on the screen.

FIG. 7 is a diagram showing a display image when the projection optical axis 10 is obliquely projected onto the screen 2 using these projection type display devices 1. (A) in FIG.
The projection angle φ with respect to the projection optical axis 10
In other words, when the projection image is projected obliquely to the screen 2, the displayed image has a trapezoidally distorted shape as shown in (b-1) and (b-2) in FIG. In addition, as shown in (a) of FIG. 7, in the left and right portions on the screen 2, the projection distance L _{R from} the projection device 1 is
Since L _L is greatly different, the image forming distance of the display image does not fall within the depth of field of the projection lens, and a focus shift (image defocusing) occurs due to the difference in the projection distance.

[0005]

By the way, in the case of projecting from the front of the screen, a projection type display device is installed in a place where an observer is present, or the projection type display device is between the observer and the screen so as not to obstruct the view. Therefore, the installation location of the projection type display device may be limited with respect to the screen because of such installation. In such a case, if the projection can be performed in an oblique direction, the restriction is relaxed. In addition, when projecting from behind the screen, a wide projection space is required behind the screen, and in order to compensate for this, it is necessary to make an attempt to reduce the space behind by bending the projection optical axis by mirror reflection. It was In this case, if the image can be projected correctly on the screen even from an oblique direction, the restriction on the installation place of the projection display device is eased without installing a mirror.

Further, Japanese Patent Application No. 6-257 filed by the present applicant.
In the display device shown in Japanese Patent No. 234, by using a display screen having a special function, not only one type of front projection image is observed from the same screen, but the difference in the viewing angle with respect to the screen It has been proposed that an image appears to change, in other words, various images can be observed by aligning the observation directions with the projection optical axes of a plurality of projection display devices by changing the observation angle. As a screen having such a special function, it has a microscopically small dispersion angle characteristic with respect to incident light,
Those that have a light-collecting function over the entire screen, for example, microlens diffusion sheets that disperse light incident angles as the center, lenticular lenses that disperse light incident angles as the center, and convex lenses A combined screen is used. When a plurality of projection devices with different projection angles are projected on the same display screen, if the dispersion angle of the display screen is set smaller than the projection angle difference between the projection devices, this setting and Depending on the function, each projected image can be observed with good separability in a plurality of observation areas having different observation directions. A display image that can be observed in an oblique direction on such a display device is an oblique projection display corresponding to the oblique observation angle.

However, if oblique projection is performed by the conventional projection method from the front side or the back side of the screen, the display image becomes a trapezoidal distorted shape as described with reference to FIG. Since the projection distance between the part near the projection type display device and the part far from the projection type display device differs greatly, the distance at which the display image is formed does not fall within the depth of field of the projection lens, and the focus due to the difference in the distance between the projection type display device and the screen. There is a problem that a shift (out-of-focus image) occurs.

The present invention has been made to solve the above problems, and an object thereof is to provide a display device which eliminates distortion due to oblique projection and removes out-of-focus images of a display image. It is in.

[0009]

In order to achieve the above object, a display device of the present invention is a display device for projecting and displaying a projection image on a screen from a projection type display device installed obliquely in front of or behind the screen. In which the video signal of the projected video is input to the video display of the projection type display device to display the video before it is subjected to distortion correction, and the projection of the video display or the projection type display device. Means for tilting the lens with respect to the projection optical axis by an angle corresponding to the tilt angle of the screen.

According to the present invention, in the above display device, the means for adding distortion correction to a video signal includes a memory for storing video data for video display, and a memory address when the video signal is written as video data in the memory. And a control means for converting the video data according to the distortion correction address and writing the video data and then inputting the video data from the memory as a video signal to the video display of the projection type display device, or a video for displaying the video. A memory for storing data and a video signal is temporarily stored in the memory as video data, and when the video data is read from the memory, a memory address is read according to a distortion correction address as a read video signal on a video display of a projection display device. And input control means.

Further, according to the present invention, in the above display device, the control means has a conversion memory, and the distortion correction address previously stored in the conversion memory is taken out and used, or the conversion calculation means is used. It is characterized in that the distortion correction address obtained at any time by this conversion calculation means is used.

[0012]

In the display device of the present invention, the distortion of the projected image on the screen caused by obliquely projecting from the projection type display device onto the screen is corrected in advance in the reverse direction of the distortion, and the image having the correct shape is obtained. To be able to display. Furthermore, rather than inclining the image display body or the projection lens of the projection display device by an angle corresponding to the inclination angle of the screen with respect to the projection optical axis, defocus (image out-of-focus) caused by oblique projection is removed. To do.

The distortion of the projected image can be obtained by converting the memory address into a distortion correction address when writing the image signal in the memory, writing the same, then reading from the memory and transferring it to the image display body, or by converting the image signal. It is removed by temporarily storing it as video data in the memory, and when reading from this memory, the address of the memory is read from the memory according to the distortion correction address and transferred to the video display.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the display device of the present invention. In this embodiment, the projection display device 1, the screen 2, the distortion correction circuit 3 for the video signal, the video display body 4 and the projection lens 5 in the projection display device 1, and the video display body 4 or The rotation adjusting unit 6 rotates the projection lens 5 with respect to the projection optical axis 10.
The input video signal 11 is subjected to distortion correction processing by image processing in the distortion correction circuit 3 and then input to the projection video device 1 to be displayed on the video display 4 of the projection video device 1 and, through the projection lens 5, the projection optical axis 10. It is projected on the screen 2 which is installed obliquely with respect to.

FIG. 2 is a diagram showing the arrangement of a video display and a projection lens for forming an image uniformly on an oblique screen. As shown in FIG. 2A, when the screen 2 is inclined with respect to the projection optical axis 10 by an inclination angle φ equal to the projection angle, what is the inclination direction of this inclination angle φ with respect to the projection optical axis 10. The image display 4 is tilted in the opposite direction by ω by the rotation adjusting unit 6. Alternatively, as shown in FIG. 2B, the projection lens 5 is tilted by the rotation adjusting unit 6 in the same direction as the tilt angle φ of the screen 2 with respect to the projection optical axis 10. The inclination angle ω of the image display body 4 and the inclination angle of the projection lens 5 can be easily calculated by calculation if the installation position is fixed.
Actually, it is convenient to perform the adjustment. As described above, the image of the image display body 4 can be uniformly formed on the inclined screen 2. F in the figure indicates the focal length of the projection lens 5, and the broken line indicates how the image is focused on the inclined screen 2 by the above adjustment. The above adjustment may be performed by inclining both the image display body 4 and the projection lens 5.

FIG. 3 shows a projection type optical device 1 when a projection image is projected by radial projection light which spreads vertically and horizontally.
FIG. 6 is a diagram showing the spread of the projected image light from the projection lens 5 to the non-inclined screen 12 and the inclined screen 13. Display images a and A are projected on a screen 12 (VT surface) installed perpendicularly to the projection optical axis 10, and display images b and B are projected on a screen 13 (SC surface) installed obliquely at an inclination angle φ. Indicates. Images a and A on the VT surface are images used in the front projection which is conventionally used. An image a without distortion at the time of front projection becomes an image b distorted by oblique projection on the screen 13 (SC surface). However, the image required as the projected image on the SC surface is the image B without distortion, and the corresponding image at the time of front projection is the image A which is the opposite of the image b. In other words, the image on the image display may be corrected and projected like the image A.

FIG. 4 shows these relationships. 4A is an image of each part when the image signal is projected as it is without distortion correction, and FIG. 4B is an image of each part when distortion correction is performed. The images 100 and 103 of the image display 4 and the images 101 and 104 on the VT surface have a similar relationship in that they have the same size but the same shape due to projection enlargement. On the other hand, the image on the screen 12 (VT surface) and the screen 1
The image on 3 (SC surface) differs depending on whether the radial projection light is vertically symmetrical with respect to the projection optical axis 10 or not,
For example, there is a trapezoidal distortion relationship when vertically and horizontally symmetrical.
Therefore, in order to make the normal figure 105 on the SC surface of the diagonal screen 13, the image 10 of the figure opposite to the distorted figure 102 is displayed.
It may be transformed into 4. Therefore, for the image displayed on the image display body, the input image 100 may be reversely corrected like the image 103.

The distortion of the image on the diagonal screen has been described above when the radial projection light is vertically and horizontally symmetrical. However, in addition, when the radial projection light spreads only upward in the vertical spread, various radiations can be emitted. Morphology is possible. However, in any form, the image on the VT surface and the image on the SC surface have a one-to-one correspondence, and the projection distance, the oblique projection angle,
It is represented by the following correspondence equation determined by the size of the screen.

That is, the coordinates on the VT plane are (x _v ,
y _v ), (x _v ', y _v '), the coordinates on the SC plane are (x _s , y
_{s), (x s ',} y s' is represented _{by), x v = f x (} x s), y
_v = f _v (y _s ), or x _s '= f ^-1 _x (x _v '),
Since the coordinates of the VT plane and the SC plane can be converted one-to-one like y _s ′ = f ⁻¹ _y (y _v ′), distortion correction may be performed according to these equations.

FIG. 5 shows an embodiment of a distortion correction circuit for performing distortion correction processing on a video signal before inputting to the projection type display device. This distortion correction circuit includes an input processing unit 200, a frame memory 201, a conversion map memory 202, and a control unit 20.
3 and the output processing unit 204. Input processing unit 20
0 indicates that when the input video signal 11 is a composite signal, the input video signal 11 is the video data 210 and the clock signal 21.
It is separated into 1 and 212, and when it is an analog signal, it is converted into digital data. In the control unit 203, the clock signal 212
To generate the memory address 213 and send the correction address 214 in the conversion map memory 202 to the frame memory 201, and also send the memory control signal 215 to write the video data 210 or read the video data 216. Or The output processing unit 204 converts the read video data 216 into an analog signal according to the input specifications of the projection type display device, or the video data 21.
6 and the clock signal 211 are combined to create an output video signal 217.

The input video signal 11 is either a TV signal (an interlaced video signal such as an NTSC signal or an HD signal) or a computer video signal (a non-interlaced video signal used for a workstation, a personal computer (PC) or the like). In the case of signals, the distortion correction circuit has the same configuration. In the case of an analog video signal, A / D conversion is required for the input processing unit 200 and D / A conversion is required for the output processing unit 204, and A / D conversion and D / A conversion are not required for a digital video signal. In the case of a composite signal in which video data and a clock signal are mixed, the input processing unit 200 has a decoder,
An encoder is required for the output processing unit 204. A memory that converts an interlaced video signal into a non-interlaced signal and provides the frame memory 201 with two surfaces, a front memory and a back memory, and when one is writing, the other is read. Make it work. In the case of the interlaced video signal, the resolution is lowered, but as a simple method, the even field memory and the odd field memory may be operated as the front memory and the back memory, respectively.

In any case, the distortion caused by oblique projection can be eliminated by performing the following distortion correction processing on the input video signal 11.

First, from the input video signal 11 to the control unit 203
The dot clock is counted with and the count value t _x
To the horizontal address x _s , counting the number of scanning lines,
When the count value t _{y is associated} with the vertical address y _s ,
The video signal at time (t _x + _ty ) corresponds to the coordinates (x _s , y _s ) of the video before correction.

Therefore, the frame memory 2 is stored in (t _x + t _y ).
When writing the video data 210 to 01, the address (x
Instead of writing to _s , y _s ), it is written to the address (x _v , y _v ) of the coordinates indicating the figure corrected by the inverse distortion. This address is the above-mentioned x _v = f _x (x _s ), y _v = f _y
These are the coordinates on the VT plane represented by (y _s ), and the coordinates before correction (the corrected image is projected on the diagonal screen SC plane to be a normal figure, so even on the SC plane coordinates (Corresponding to (x _s , y _s )) is written in the conversion map memory 202 in advance. Time (t _x + _ty )
, The frame memory 2 indicated by the correction address (x _v , y _v ) at the address (x _s , y _s ) of the conversion map memory 202.
The video data 210 is written to the address 01. After all the writing is completed by such an operation, the frames are sequentially read from the frame memory 201 and output to the projection display device.

In the above description, the conversion map memory 202 is used when writing to the frame memory 201. Conversely, on the contrary, the input video data 210 is faithfully stored in the frame memory, and when it is read out, the figure is corrected. As described above, the correction can be performed by reading the data from the frame memory based on the frame address in the conversion map memory created in advance. A frame memory address to be written in the conversion map memory this time, the conversion map x _s was inversely converts the contents of the memory _{^{202 '= f -1 x (x}} v'), y s' = f -1 y (y v ')
And is a time (t _x + t _y) on the converted map memory address _{(x v ', y v'} ) is in the _{(x s ', y s'} ).

In the embodiment of the present invention, when the correction address is written in the frame memory or read from the frame memory, the correction address is previously written in the conversion map memory and read from the conversion map memory for use. However, without using such a conversion map memory, the conversion formula x _v directly indicating the correction address is obtained.
= F _x (x _s ), y _v = f _v (y _s ), or x _s ' = f ^-1
_The correction address may be calculated according to _x (x _v '), y _s ' = f ^-1 _y (y _v '), and the calculation result may be used to write or read to the frame memory. In this case, the conversion map memory 202 shown in FIG. 7 may be replaced with a conversion calculation unit.

When the conversion calculation unit is used, it is easy to change the projection angle and the projection distance, which are the conditions of the calculation, and the installation position of the projection type display device is corrected,
It can easily respond to changes or changes. Although the conversion map memory is slightly smaller than the frame memory, it is large in terms of hardware,
The use of the conversion calculator has the advantage of reducing the hardware scale. However, since the correction address must be calculated in real time according to the input video signal, it is necessary to use a high speed element. In this respect,
The use of the conversion map memory has the advantage that it can be processed at high speed.

In the embodiment of the present invention, the video data is written in the address of the corresponding frame memory by the correction address and the video data is read from the frame memory. However, not only video data at the address indicated by such a correction address but also video data at addresses around the correction address may be included in the video data to be written or read after the weighted average processing is performed. Depending on the situation, the process of smoothing the image may be performed. However, when performing weighted averaging by a method of performing correction when writing to the frame memory, it is necessary to store previously input video data before weighted averaging and writing and use it for calculation.

[0030]

As described above, according to the display device of the present invention, the distortion of the projected image on the screen caused by obliquely projecting on the screen is corrected in advance by the image processing to the opposite of the distortion. Therefore, the image with the correct shape can be displayed despite the oblique projection. Further, since the image display body or the projection lens of the projection type display device is tilted by an angle corresponding to the tilt angle of the screen with respect to the projection optical axis, a focus shift (image defocusing) caused by oblique projection occurs. Does not occur. Therefore, it is possible to realize a projected image without distortion and out of focus by oblique projection.

Conventionally, the projection position is constrained to be perpendicular to the screen, so that the installation position of the projection device is restricted. However, since the display device of the present invention is capable of oblique projection, the restriction of the installation position is alleviated. It

Furthermore, by changing the observation angle with respect to the same screen having a microscopically small dispersion characteristic and a light condensing function over the entire surface, the observation directions can be set to the projection optical axes of a plurality of projection type display devices. In the display device shown in Japanese Patent Application No. 6-257234 which allows various images to be observed together, when a display image that can be observed from an oblique direction is obliquely projected and displayed corresponding to this oblique observation angle, By applying the display device of the present invention, it is possible to display without distortion and out of focus, and thus display with high display quality and high reality can be realized.

In the present invention, the image processing of writing and reading the video data to and from the corresponding memory address according to the correction address is used, so that the distortion of oblique projection can be easily corrected. At this time, when a conversion memory in which the correction address is stored in advance is used as a means for obtaining the correction address, there is an advantage that the processing can be performed at high speed. Further, when the conversion calculation means is used as the same means, it is possible to easily cope with the variation of the installation position of the projection type display device and to reduce the scale of hardware.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an exemplary embodiment of the present invention.

2 (a) and 2 (b) are views showing the arrangement of an image display body and a projection lens for uniformly forming an image on an oblique screen in the present invention.

FIG. 3 is a diagram illustrating an image displayed on each of the tilted and non-tilted screens when radial projection light is projected from the projection display device.

4 (a) and 4 (b) are diagrams for explaining an image on an image display body and an image on a tilted screen and a non-tilted screen when a video signal is not corrected and when it is added.

FIG. 5 is a diagram showing the configuration of an embodiment of a distortion correction circuit that performs distortion correction processing on an input video signal according to the present invention.

FIG. 6 is a diagram showing a display image when a conventional display device is used to project a projection optical axis so as to be perpendicular to a screen.

FIG. 7 is a diagram showing a display image when a projection optical axis is obliquely projected on a screen using a conventional display device.

[Explanation of Codes] 1 ... Projection display device 2 ... Screen 3 ... Distortion correction circuit 4 ... Image display body 5 ... Projection lens 6 ... Rotation adjusting unit 10 ... Projection optical axis 11 ... Input video signal 12 ... Vertical to projection optical axis Screen (VT surface) 13 ... Screen oblique to the projection optical axis (SC surface) 100, 103 ... Display image on image display body 101, 104 ... Display image on VT surface 102, 105 ... Display image on SC surface Reference numeral 200 ... Input processing unit 201 ... Frame memory 202 ... Conversion map memory 203 ... Control unit 204 ... Output processing unit 210 ... Video data 211, 212 ... Clock signal 213 ... Memory address 214 ... Correction address 215 ... Memory control signal 216 ... Read data 217 ... Output video signal

Claims (5)

[Claims] 1. A display device for projecting and displaying a projected image on a screen from a projection type display device installed diagonally in front of or behind the screen, wherein a video signal of the projected image is input to a video display of the projection type display device. Means for applying distortion correction to the image signal in advance before displaying the image, and an angle corresponding to the inclination angle of the screen with respect to the projection optical axis of the projection lens of the image display body or the projection display device. A display device comprising: a means for inclining. 2. The display device according to claim 1, wherein the means for adding distortion correction to the video signal is a memory for storing video data for video display, and a memory for writing the video signal as video data in the memory. A control unit for converting an address according to a distortion correction address and writing the data, and thereafter, reading the video data from the memory and inputting the video data as a video signal to a video display body of a projection type display device. 3. The display device according to claim 1, wherein the means for adding distortion correction to the video signal includes a memory for storing video data for displaying the video, and a video signal once stored in the memory as the video data.
Control means for inputting a memory address as a read video signal to a video display of the projection display device in accordance with a distortion correction address when reading the video data from the memory. 4. The display device according to claim 2, wherein the control unit has a conversion memory, and the distortion correction address stored in advance in the conversion memory is taken out and used. Display device. 5. The display device according to claim 2 or 3, wherein the control means has a conversion operation means, and the distortion correction address obtained at any time by the conversion operation means is used. .