JP2006013944A - Device for correcting trapezoid of projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display a rectangular image having no omission of an image and less distortion on a screen even when the installation elevation angle of a projector to the screen is large. <P>SOLUTION: The device for correcting a trapezoid of a projector is provided with correction keys 4 composed of a (-) key which instructs the trapezoid correction in the direction of reducing an image to the image on the screen, and a (+) key which executes the trapezoid correction in the direction of magnifying the image. When the operation of the (+) key after the continuous operation of the (-) key is executed, it is regarded that the trapezoid correction is in an over-correction state of exceeding the predetermined upper limit correction. Then, vertical reduction correction for reducing the image vertically is executed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a keystone correction apparatus for a projector that uses a light modulation element of a liquid crystal projector or a DMD (digital micromirror device).

When changing the installation angle of the projector with respect to the screen, generally, the trapezoidal distortion on the screen increases as the elevation angle of the projector with respect to the screen increases. Therefore, conventionally, a trapezoidal correction unit as shown in Patent Document 1 or Patent Document 2 is provided to correct the trapezoidal image on the screen to be rectangular. The keystone correction may be automatically performed by detecting the installation angle of the projector as disclosed in Patent Document 2 or by key operation on the operation panel.
JP 2001-249401 A JP 2003-5278 A

  However, in the projectors shown in Patent Document 1 and Patent Document 2, since a predetermined upper limit that allows trapezoid correction is usually set, when the projector is installed at a very large elevation angle with respect to the screen, Since trapezoidal correction is not sufficiently performed, trapezoidal distortion, particularly vertical distortion, may not be eliminated.

  This state is shown in FIG.

  5A shows a screen display state that does not require keystone correction. The state shown in FIG. 5A is realized when the projector is installed at a small elevation angle with respect to the screen. FIG. 5B shows a case where the projector is installed at a slightly shallow elevation angle with respect to the screen. In this case, if trapezoid correction is not performed, an image on the trapezoid indicated by X is displayed on the screen. However, by performing the trapezoid correction, the image is reduced in the direction of the arrow in FIG. It is corrected to the image.

  FIG. 5C shows a case where the projector is installed at a very large elevation angle with respect to the screen. In this case, since the trapezoidal correction reaches the upper limit, the image near the upper end of the image Y with the maximum correction is missing.

  As described above, when the projector is installed at a large elevation angle with respect to the screen, the conventional trapezoidal correction device cannot perform sufficient trapezoidal correction, and as a result, there is a disadvantage that the upper end portion of the image on the screen is missing. there were.

  An object of the present invention is to provide a rectangular image with no image defect and little distortion by forcibly reducing image data by a certain length or a certain ratio in the vertical direction when the keystone correction exceeds a predetermined upper limit. Is to provide a keystone correction device for a projector.

  The present invention provides a projector that projects image data on a screen, a trapezoid correction unit that performs keystone correction on the image data, a correction instruction unit that issues a correction instruction to the keystone correction unit, and the correction instruction unit A vertical reduction correction unit that corrects the image data in the vertical direction when the keystone correction by the trapezoid correction unit based on the instruction is in a correction over state exceeding a predetermined upper limit correction. Features.

  According to the present invention, the keystone correction on the operation panel enables the keystone correction by manual input, and the user operates the correction instruction unit while viewing the actual image on the screen. The trapezoidal correction is performed by an arbitrary amount so that a rectangular image that is easy for the user to see can be obtained. However, when the projector is installed at a large elevation with respect to the screen, the upper limit value is reached even if the keystone correction is performed as shown in FIG. Therefore, in this case, correction is performed to reduce the image data by a fixed length or a fixed rate in the vertical direction. As a result, the image displayed on the screen is a rectangular image with no missing image and no distortion.

  The correction instruction means can be composed of a first correction instruction key for correcting image data in the reduction direction and a second correction instruction key for correction in the enlargement direction. Then, if the second correction instruction key is operated after the first correction instruction key is operated continuously, the reduction correction is performed assuming that the correction is over. Therefore, the user reduces the image step by step with the first correction instruction key, and when the user knows that the upper limit at which the image is not further reduced is reached, the user operates the second correction instruction key at that time. To do. At this time, the user has determined the upper limit of the keystone correction and has operated the second correction instruction key. Therefore, at this time, the projector detects that the correction is in an overcorrection state, and performs reduction correction in the vertical direction.

  In addition, an image sensor is provided for recognizing the shape of the image on the screen. Based on the sensor output, it is determined whether or not the upper limit of the trapezoidal correction has been reached, and when the upper limit is reached, vertical reduction correction is performed. May be.

  According to the present invention, even when the projector is installed in a narrow room where the distance between the screen and the projector cannot be taken much, such as when the elevation angle of the projector with respect to the screen has to be large, the screen has no problem for the user. It is possible to display a rectangular image that is very easy to see.

  FIG. 1 is a configuration diagram of a main part of a projector to which an image display apparatus according to an embodiment of the present invention is applied.

  A video signal composed of a composite signal or the like is separated into a synchronization signal and an image signal by the signal separation unit 1. Among the synchronization signals, VSYNC is input to the control unit 2, and R (red), G (green), and B (blue) image signals are input to the image control unit 3. A signal from a correction key 4 for trapezoidal correction for an image on the screen is input to the control unit 2. The + key of the correction key 4 is a key for enlarging an image, and the-key is a key for reducing an image.

  A control signal from the control unit 2 is input to the lamp driving unit 5, the rotation driving unit 6, and the image control unit 3.

  The lamp driving unit 5 drives a white light source 10 composed of a halogen lamp or the like, and the light is collected by an elliptical mirror 11 and passes through a color wheel 12 and enters a rod lens 13. In the rod lens 13, the illuminance distribution is converted to a uniform state, and is guided to a light modulation element 17 such as a DMD (digital micromirror device) via the relay lenses 14 and 15 and the concave reflecting mirror 16. The light that is light-modulated with the image signals of red, green, and blue by the light modulation element 17 is guided to a screen (not shown) via the projection lens 18.

  The color wheel 12 has R, G, and B color filters, and is rotated by a motor 19 at a constant rotation frequency. The motor 19 is driven by the rotation drive unit 6. A reference mark 21 is provided on the rotating portion 20 provided coaxially with the rotating shaft of the motor 19. A reference mark detection sensor (reference timing detection sensor) 22 is provided to detect the reference mark 21, and a detection signal from the reference mark detection sensor 22 is input to the control unit 2.

  With the above configuration, the control unit 2 performs light modulation based on image data in the light modulation element 17 on the light color-separated by the color wheel 12 and projects the light on the screen. Since the rotation position of the color wheel 12 is accurately detected by the reference mark detection sensor 22, the light modulation for the color-separated light is always performed correctly.

  The control unit 2 includes a frame memory for storing image data, and performs keystone correction on the frame memory based on the operation of the correction key 4. The trapezoidal correction is correction that eliminates the trapezoidal distortion of the image displayed on the screen, and is performed by thinning-out processing (reduction) or interpolation processing (enlargement) of pixel data.

  FIG. 2 is a flowchart showing the operation of the keystone correction process of the projector.

  When the correction key 4 is operated (ST1), a reduced trapezoid correction process (ST2) and an enlarged trapezoid correction process (ST3) are performed on the frame memory according to the type of the + key and the-key. Since the result appears on the screen, the user repeats these key operations as necessary while watching the correction state.

  Subsequently, it is determined whether or not the + key has been operated after the continuous operation with the-key (ST4). In the present embodiment, if the + key is operated after the continuous operation by the − key, it is considered that the trapezoidal correction is in an over-correction state exceeding a predetermined upper limit correction. At this time, the image data is forcibly reduced and corrected by a fixed rate in the vertical direction (ST5). This reduction correction is performed by thinning out the pixel data in the vertical direction. The thinning rate is increased toward the upper side.

  The over-correction state is a state in which keystone correction cannot be performed even if the − key is operated, and this upper limit value is predetermined by the apparatus. In the present embodiment, the control unit 2 knows that the correction over state has been detected by detecting that the user has performed a + key operation after a continuous operation of the-key. Therefore, at this time, the reduction correction in the vertical direction is performed.

  Thereby, even if the image is as shown in FIG. 5C, it is possible to prevent the image on the screen from becoming difficult to see due to the reduction operation in the vertical direction. In ST5, since the trapezoidal correction including the vertical and horizontal reduction corrections is not performed, it is possible to prevent the image shape from becoming too small.

  FIG. 3 shows another embodiment of the present invention.

  The difference between this embodiment and the embodiment shown in FIG. 2 is that the correction key 4 is composed of a −key, a + key, and a vertical key (not shown), and in the step ST4 ′, the −key or + key is changed. When the vertical key is operated after the operation, the vertical reduction correction is performed in ST5. The vertical key becomes effective after the keystone correction is performed by operating the-key or the + key. Therefore, after operating the − key or the + key to correct the keystone, the user operates the vertical key when he / she thinks that the keystone correction has exceeded the predetermined upper limit correction. Then, in ST5, reduction correction in the vertical direction is performed.

  4 and 5 show still another embodiment of the present invention.

  As shown in FIG. 5, in this embodiment, an image sensor 32 that recognizes the shape of an image shown on the screen 31 is provided in the projection unit of the projector main body 30. The output of the image sensor 32 is input to the control unit 2, and the image on the screen 31 recognized by the image sensor 32 in the control unit 2 is in an overcorrected state in which the keystone correction is not performed even if the correction key 4 is operated. Judge whether.

  That is, as shown in FIG. 4, as a result of the correction operation performed in ST2 or ST3, it is determined in ST4 ′ whether or not the keystone correction has been performed based on the image detected by the image sensor 32, and the keystone correction has not been performed. In this case, it is assumed that the trapezoidal correction is in the overcorrection state exceeding the predetermined upper limit correction, and the vertical reduction correction is performed in ST5.

  When the trapezoidal correction exceeds the predetermined upper limit correction by the above control, the vertical reduction correction is forcibly performed. For example, the projector is operated at a large elevation angle with respect to the screen. Even when installed, the image on the screen is a rectangular image that is easy to see.

Schematic configuration diagram of a projector according to an embodiment of the present invention Flow chart showing the operation of keystone correction processing The flowchart which shows the operation | movement of the trapezoid correction process in other embodiment. A flowchart showing the operation of trapezoidal correction processing in still another embodiment. Diagram showing the arrangement of image sensors Diagram for explaining keystone correction

Claims (5)

In a projector that projects image data on a screen,
A keystone correction unit that performs keystone correction on the image data;
Correction instruction means for issuing a correction instruction to the trapezoid correction unit;
A vertical reduction correction unit that corrects the image data in the vertical direction when the keystone correction by the trapezoid correction unit based on an instruction from the correction instruction unit exceeds a predetermined upper limit correction. Prepared,
The correction instruction means includes a first correction instruction key for correcting the image data in the reduction direction and a second correction instruction key for correcting in the enlargement direction.
The vertical reduction correction unit performs the reduction correction on the assumption that the correction is over when the second correction instruction key is operated after the first correction instruction key is continuously operated. An image correction apparatus for a projector. In a projector that projects image data on a screen,
A keystone correction unit that performs keystone correction on the image data;
Correction instruction means for issuing a correction instruction to the trapezoid correction unit;
A vertical reduction correction unit that corrects the image data in the vertical direction when the keystone correction by the trapezoid correction unit based on an instruction from the correction instruction unit exceeds a predetermined upper limit correction. An image correction apparatus for a projector, comprising: The correction instruction means includes a first correction instruction key for correcting the image data in the reduction direction and a second correction instruction key for correcting in the enlargement direction.
The vertical reduction correction unit performs the reduction correction on the assumption that the correction is over when the second correction instruction key is operated after the first correction instruction key is continuously operated. The image correction apparatus for a projector according to claim 2. The correction instruction means includes a first correction instruction key for correcting the image data in the reduction direction, a second correction instruction key for correcting in the enlargement direction, and a third correction instruction for instructing the reduction correction in the vertical direction. Key and
The vertical reduction correction unit performs the reduction correction on the assumption that the correction is over when the third correction instruction key is operated after the first correction instruction key is operated continuously. The image correction apparatus for a projector according to claim 2. It has an image sensor that recognizes the shape of the image on the screen,
The vertical reduction correction unit includes means for determining whether the trapezoidal correction of the image on the screen recognized by the image sensor is in the overcorrection state based on a correction instruction from the correction instruction means, 3. The image correction apparatus for a projector according to claim 2, wherein the reduction correction is performed when it is determined that the image is in a state.

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