JP2006074593A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector, having structure to reflect correction by lens shift on keystone correction, and to preferentially use lens shift function. <P>SOLUTION: The projector is equipped with a keystone correction part which applies the keystone correction to an inputted video signal, a display element for displaying a video, on the basis of the output signal of the keystone correction part, a projection lens which projects the video displayed on the display element to a screen, a lens drive part 18 which moves the projection lens and outputs its positional information, and a control part 17 which outputs the positional information of a parameter and a lens to be used for the keystone correction to the keystone correction part 12. In the control part 17, whether the amount of movement of the lens has reached a limit value is decided; only when it has reached the limit value, will the input of a signal for keystone adjustment of contents for changing the parameter used for the keystone correction be accepted and outputted to the keystone correction part 12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a projection type projector that arranges a projector in front of a screen, projects an image on the screen, and views the image projected from the screen. When projecting an image using the projection type projector, the present invention relates to a projection type projector. This relates to the image quality correction to be performed.

  2. Description of the Related Art Conventionally, as a type of projector, there is a projection type projector that places a projector in front of a screen, projects an image on the screen, and views the image projected from the screen. In this case, the projector is installed so that the projection direction and the screen surface are perpendicular to each other, and the center of the projected image from the projector and the center of the screen are on the same horizontal line and are displayed on the screen from the projected image center of the projector. It is desirable to arrange so that the projection angles to the top and bottom and left and right edges of the image to be equalized. However, since it is not always possible to install a projector in front of the screen, functions corresponding to this include a keystone correction function that is a correction means by image processing and a lens shift function that is a correction means by an optical system.

  The keystone correction function is a function for correcting distortion generated when an image is projected from an oblique direction on the screen. For example, if the image area displayed on the screen when the image is projected from the front on the screen is in a rectangular state as shown in FIG. When projected, the difference in distance to the screen results in a trapezoidal state in which the upper side extends with respect to the lower side as shown by the solid line in FIG. Is a trapezoidal state in which the lower side extends with respect to the upper side as shown in FIG. Similarly, when projected on the screen diagonally from the right side, it is displayed as a trapezoid in FIG. 5D, and when projected on the screen diagonally from the left side, it is displayed as a trapezoid in FIG. 5E. End up. In addition, when images are projected on the screen from the lower right, upper right, lower left, and upper left directions, the images shown in FIGS. 5 (f), (g), (h), (i ) Will be displayed as a deformed rectangle.

  A function for correcting such image distortion is keystone correction, and the horizontal and / or vertical scaling factor is changed on a display element such as a liquid crystal display so that the distortion on the screen and the display element are corrected. By adjusting so that the distortion of the video area is offset and projecting the distorted video, it can be displayed on the screen as a rectangular video display area having a normal aspect ratio. In the keystone correction, if the angle is within a certain range, a distorted quadrangle can be corrected to the original rectangle and output, however, the image quality is slightly deteriorated.

  On the other hand, the lens shift function is a function of translating the image display area displayed on the screen by adjusting the position of the lens provided at the rear stage of the light source and the display element. As shown in FIG. 6, the position of the image on the screen is shifted by adjusting the position of the lens. For example, the image area on the screen when the lens position is the origin is shown in FIG. ), The position of the lens is adjusted to adjust the display area by parallel movement while maintaining the size of the rectangle at the origin as shown in FIGS. Can be changed. Of course, it goes without saying that adjustment is possible in all directions including the vertical and horizontal directions not shown. The correction by this lens shift function has an advantage that the image moving area on the screen is limited because the operating range of the lens is small, but the image quality is hardly deteriorated.

  As described above, there are a keystone correction function that is a correction means by image processing and a lens shift function that is a correction means by an optical system as correction means when using a projection type projector, and these correction means are appropriately selected. Can be used to correct a rectangle with a normal aspect ratio.

  However, for example, as shown in FIG. 6D, after the image display area is translated in the diagonally upper right direction by the lens shift function, as shown in FIG. If the image is projected in an oblique direction, the image display area on the screen in this case will be distorted differently from the case where the lens is at the origin position. There was a possibility that it could not be corrected to the rectangle of the ratio. In other words, since the keystone correction function and the lens shift function are independent correction means, if one correction is not reflected in the other correction and cannot be corrected using the lens shift function, the lens is temporarily removed. If the keystone correction is not performed by returning to the origin and projecting in an oblique direction with respect to the screen, it is inconvenient that the rectangle cannot be corrected to a normal aspect ratio.

  In addition, when both are used together, it is impossible to use both of the correction limits, and the rectangle cannot be corrected to a normal aspect ratio unless it is used in a range narrower than the respective correctable range. In other words, the correctable range (angle) by the lens shift function and the correctable range (angle) by the keystone correction function are set, but even if both are used, the correctable range is not the sum of the angles. Actually, unless it is used in a narrower range, there is a problem that the normal aspect ratio rectangle cannot be corrected by the keystone correction.

Because of these problems, a projector that matches the keystone correction function, which is a correction means by image processing, with the lens shift function, which is a correction means by an optical system, and reflects the correction by lens shift in the keystone correction is desired. Patent Document 1 has already been proposed to provide this.
JP 2003-195416 A

この変換式はレンズシフトによる補正がキーストン補正に反映されたものであるが、補正後の画面上の点（ｘ´，ｙ´）はあおり角が大きくなるにつれて２次曲線の特性となってしまい、きれいに補正できなくなるという問題があった。 In this patent document 1, horizontal tilt angle Kx, vertical tilt angle Ky, horizontal projection angle Tx that changes with lens shift, and vertical that changes with lens shift are used as parameters for keystone correction (distortion correction). The projection angle Ty is used, and the point (x, y) on the screen before correction is converted to the point (x ′, y ′) on the screen after correction by the following equation.

In this conversion formula, correction by lens shift is reflected in keystone correction, but the point (x ′, y ′) on the screen after correction becomes a characteristic of a quadratic curve as the tilt angle increases. There was a problem that it could not be corrected properly.

  By the way, the correction by the lens shift function has an advantage that the moving area of the image on the screen is limited because the operating range of the lens is small, but there is an advantage that the image quality is hardly deteriorated. When correction is possible by shift, it is desirable to use the lens shift function in preference to the keystone correction function. Therefore, only when the lens shift function needs to be moved beyond the range that can be moved, the image is projected obliquely from the screen, and then the keystone correction function is used to display the normal aspect ratio. By correcting the ratio to a rectangle, it is possible to minimize image quality degradation. However, the above-mentioned Patent Document 1 does not mention how to use the correction by the lens shift function and the keystone correction, and since it does not have a configuration that determines these use conditions, it can be corrected by the lens shift function. Even within this range, there is a problem that the user performs keystone correction without noticing.

  The present invention has been made in view of the above problems, and a rectangle having a normal aspect ratio can be obtained by using both a keystone correction function as a correction means by image processing and a lens shift function as a correction means by an optical system. It is an object of the present invention to provide a projector that includes a calculating means that can be corrected, and has a configuration for preferentially using correction by a lens shift function.

  According to a first aspect of the present invention, a keystone correction unit that performs image processing by keystone correction on an input video signal, a display element that displays video based on an output signal from the keystone correction unit, and the display element A projection lens that projects the image displayed on the screen using light from the light source, a lens driving unit that moves the projection lens and outputs lens position information, parameters used for keystone correction, and the lens A control unit that outputs lens position information input from the drive unit to the keystone correction unit, and in the control unit, whether the lens movement amount has reached a limit value from the lens position information input A key list that changes the parameters used for keystone correction only when the lens movement amount has reached the limit value. A projector is characterized in that so as to output the keystone correction unit accepts the input of the adjustment signal.

  According to a second aspect of the present invention, in addition to the first aspect, the control unit determines whether or not the movement amount of the lens has reached a limit value from the input lens position information. In the projector, the output from the keystone correction unit is selected, and the input video signal is selected when the limit value is not reached.

  According to a third aspect of the present invention, in addition to the first or second aspect, the control unit includes means for determining whether or not the movement amount of the lens has reached a limit value from the input positional information of the lens. When the keystone adjustment signal for changing the parameter used for keystone correction is input in a state where the lens movement amount has not reached the limit value, the lens movement amount has not reached the limit value. A projector comprising means for outputting a notification signal.

According to a fourth aspect of the present invention, a keystone correction unit that performs image processing by keystone correction on an input video signal, a display element that displays video based on an output signal from the keystone correction unit, and the display element A projection lens that projects the image displayed on the screen using light from the light source, a lens driving unit that moves the projection lens and outputs lens position information, parameters used for keystone correction, and the lens A controller that outputs lens position information input from the drive unit to the keystone correction unit, and parameters used for the keystone correction are the vertical inclination θ of the projection angle and the horizontal inclination of the projection angle. It is assumed that φ is a distance l between the light source and the display element and a distance L between the light source and the screen. It is assumed that the position information of the lens is a horizontal movement amount L _x and a vertical movement amount L _y of the lens. In the keystone correction unit, the pixel position (x, y) on the display element and the display on the screen are displayed. A projector that performs image processing by keystone correction using a relationship between the position (X, Y) and the following expression (1).

According to a fifth aspect of the present invention, in addition to the first to third aspects, the parameters used for the keystone correction include the vertical inclination θ of the projection angle, the horizontal inclination φ of the projection angle, and the distance between the light source and the display element. The distance l and the distance L between the light source and the screen are assumed, and the lens position information output from the lens driving unit is assumed to be the horizontal movement amount L _x and the vertical movement amount L _y of the lens. In the keystone correction unit, image processing by keystone correction is performed using the fact that the pixel position (x, y) on the display element and the display position (X, Y) on the screen have the relationship of the following expression (1). 4. The projector according to claim 1, wherein the projector is performed.

  According to the first aspect of the present invention, the control unit includes means for determining whether or not the lens movement amount has reached the limit value from the input lens position information, and the lens movement amount is the limit value. Because the keystone adjustment signal input that changes the parameter used for keystone correction is received only when it has reached, and is output to the keystone correction unit, correction by lens shift can be used preferentially, Since the keystone correction can be performed for the first time when the moving amount of the lens reaches the limit, it is possible to perform the correction with little deterioration in image quality.

  According to the second aspect of the present invention, the control unit determines whether or not the lens movement amount has reached a limit value from the input lens position information, and if it has reached the limit value, the keystone Since the output from the correction unit is selected and the input video signal is selected when the limit value has not been reached, correction by lens shift can be used preferentially, and the lens movement amount reaches the limit. In this case, the keystone correction can be performed for the first time, so that it is possible to perform the correction with little deterioration in image quality.

  According to the third aspect of the present invention, the control unit includes means for determining whether or not the lens movement amount has reached the limit value from the input lens position information, and the lens movement amount is the limit value. Means for outputting a signal notifying that the moving amount of the lens has not reached the limit value when a keystone adjustment signal for changing a parameter used for keystone correction is input. Since it is provided, it is possible to notify the user that correction by lens shift is still possible.

  According to the fourth aspect of the present invention, the keystone correction unit uses the fact that the pixel position (x, y) on the display element and the display position (X, Y) on the screen have the relationship of Expression (1). Since image processing by keystone correction can be performed, the problem of the prior art is solved, and after correcting the rectangle to the normal aspect ratio by performing keystone correction, the image can be translated by the lens shift function, Parallel movement can be performed while maintaining a normal aspect ratio, and appropriate keystone correction can be performed even when the projection angle increases.

  According to the fifth aspect of the present invention, the keystone correction unit uses the fact that the pixel position (x, y) on the display element and the display position (X, Y) on the screen have the relationship of Expression (1). Since image processing by keystone correction can be performed, the problem of the prior art is solved, and after correcting the rectangle to the normal aspect ratio by performing keystone correction, the image can be translated by the lens shift function, Parallel movement can be performed while maintaining a normal aspect ratio, and appropriate keystone correction can be performed even when the projection angle increases.

以下、図面を用いて詳細に説明する。 A projector according to the present invention includes a keystone correction unit that performs image processing by keystone correction on an input video signal, a display element that displays an image based on an output signal from the keystone correction unit, and a display on the display element Lens that projects the projected image onto the screen using light from the light source, a lens drive unit that moves the projection lens and outputs lens position information, parameters used for keystone correction, and the lens drive unit And a control unit that outputs to the keystone correction unit, the parameters used for keystone correction are the vertical tilt θ of the projection angle, the horizontal tilt φ of the projection angle, and the light source. And a distance L between the light source and the screen, and is output from the lens driving unit. The lens position information includes the horizontal movement amount L _x and the vertical movement amount L _y of the lens. In the keystone correction unit, the pixel position (x, y) on the display element and the display on the screen are displayed. Image processing by keystone correction is performed using the relationship between the position (X, Y) and the following expression (1), and the control unit moves the lens from the input lens position information. Means for determining whether or not the amount has reached a limit value, and a keystone adjustment signal for changing a parameter used for keystone correction is input in a state where the amount of lens movement has not reached the limit value In this case, the projector includes a means for outputting a signal notifying that the moving amount of the lens has not reached the limit value.

Hereinafter, it explains in detail using a drawing.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a projector 10 according to the present invention. In FIG. 1, the video signal input from the video signal input terminal 11 is input to the keystone correction unit 12 and is output to the subsequent display element 13 after performing necessary image processing. The display portion instructed by the image processing of the keystone correction unit 12 is turned on, and the image displayed on the display element 13 is projected onto the screen 15 by a light source (not shown) and the projection lens 14 to display the image.

  The projector 10 according to the present invention includes a keystone correction function, a lens shift function, and a zoom function. When these corrections are performed, correction is performed by a separate user operation. A lens shift adjustment signal is input to the control unit 17 from the lens shift adjustment signal input terminal 16 in accordance with a user operation for performing keystone adjustment, and a keystone adjustment signal input terminal in accordance with a user operation for performing keystone correction. A keystone adjustment signal is input from 19 to the control unit 17. The control unit 17 performs control to reflect the parameter changed by the operation performed by the user to perform the keystone correction on the keystone correction unit 12, and drives the lens by the operation performed by the user to perform the lens shift. An instruction is output to a lens driving unit 18 to be described later, and actual lens position information from the lens driving unit 18 is reflected on the keystone correction unit 12 as one of parameters. The lens driving unit 18 drives and changes the position of the projection lens 14 in accordance with a lens driving instruction from the control unit 17. The changed lens position is immediately input to the control unit 17.

Of the parameters controlled by the control unit 17, parameters of lens position information input from the lens driving unit 18 when the lens shift function is used will be described in detail. In FIG. 3, the axis on which light from the light source is projected perpendicularly to the plane on which the screen is provided is taken as the z axis, the plane with the display element 13 is taken as the xy plane, and the plane with the screen is taken as XY. A plane. When the projection lens 14 is at the origin position, it is assumed that the center o of the display element 13 is overlapped with the center of the xy coordinates. When the lens shift function is used, as shown in FIG. The center o of will move. The amount of movement of the center o in the x direction at this time is L _x, and the amount of movement in the y direction is L _y . L _x and L _y are parameters relating to the lens shift function, and a lens shift adjustment signal is input to the control unit 17 from the lens shift adjustment signal input terminal 16 in accordance with a user operation for performing the lens shift. Then, the control unit 17 issues a lens driving instruction to the lens driving unit 18, and when the lens driving unit 18 changes the lens position in accordance with the lens driving instruction, the L _x and L _y are immediately used as lens position information. Input to the controller 17.

  Next, of the parameters controlled by the control unit 17, parameters input to the control unit 17 as a keystone adjustment signal from the keystone adjustment signal input terminal 19 in accordance with a user operation for performing keystone correction will be described in detail. To do. Here, the necessity of performing the keystone correction means that an image is projected from any oblique direction with respect to the screen. If the projection angle with respect to the screen becomes clear, the keystone correction is accurately performed. be able to. As shown in FIG. 4A, with reference to the case where the projector 10 is arranged in front of the screen, the projection angle (tilt in the vertical direction) that occurs when the image is projected onto the screen with the projector moved in the vertical direction. ) Is θ. Further, as shown in FIG. 4B, with reference to the case where the projector 10 is arranged in front of the screen, a projection angle (left-right direction) generated when an image is projected on the screen with the projector moved in the horizontal direction. ) Is φ. The θ and φ are input to the control unit 17 as parameters relating to keystone correction. However, the projection angles θ and φ are determined from the adjustment amount when the user determines that the correct aspect ratio is obtained by performing adjustment while viewing the distorted video.

Wherein the keystone correction unit 12, and the projection angle θ and φ is a parameter related to keystone correction function described above, the lens movement amount L _x and L _y is a parameter related to lens shift function is inputted. As shown in FIG. 3, the distance from the light source to the xy plane including the display element 13 is l, and the distance from the light source to the XY plane including the screen 15 is L. The value is also input to the keystone correction unit 12 as a parameter. The value of L may be automatically measured by providing a distance sensor, may be arbitrarily set, or may be a constant assuming a generally used distance. The value of l is a parameter that changes with zooming, and is obtained from the following equation (2) using the size of the display element, the size of the image on the screen, and the value of the distance L to the screen. be able to.

Next, the flow of image processing in the keystone correction unit 12 will be described. If the coordinates (x, y) of an arbitrary pixel on the display element 13 in the xy plane of FIG. 3 are projected to the (X, Y) point on the screen 15 in the XY plane, these ( The relationship between (x, y) and (X, Y) can be expressed as follows using the previously input parameters θ, φ, L _x , L _y , l and L.

  According to the above equation (1), it is possible to calculate where on the screen 15 an arbitrary pixel (x, y) on the display element 13 is projected. Therefore, using this equation (1), first, the coordinates when the four vertices of the display element 13 in the xy plane are projected on the screen 15 are calculated. When projected obliquely to the screen 15, the four vertices of the display element 13 form a quadrangle on the screen 15 in the XY plane. As shown by the broken lines in FIGS. 5B to 5I, a rectangular area having a normal aspect ratio can be selected from the rectangle, and the selected rectangle having the normal aspect ratio can be selected. This time, the coordinates of the four vertices of the rectangle on the display element 13 are obtained by calculating backward from the above equation (1). The four points on the display element 13 obtained in this way form a quadrangle. By deforming the input video signal so as to be within the distorted quadrangle, the distorted quadrangle is projected on the contrary. The video can be displayed on the screen 15 as a rectangle having a normal aspect ratio.

As described above, in the video signal input from the video signal input terminal 11, which pixel on the display element 13 is lit is determined based on the relationship expressed by the above formula (1) in the keystone correction unit 12. The In Expression (1), parameters θ and φ related to keystone correction that is correction by image processing, parameters L _x and L _y related to lens shift function that are correction by an optical system, and parameters l and L related to zoom function are all reflected. When any of these corrections is performed, the parameters relating to the correction are immediately reflected in the expression (1) of the keystone correction unit 12 via the control unit 17.

  As described above, in the present invention, since the parameters related to all the correction functions are reflected in the above formula (1), even if both the keystone correction and the correction by the lens shift function are used in combination, the normal aspect ratio and Can be corrected to a rectangle. In addition, unlike the calculation formula in Patent Document 1, since it does not have the characteristics of a quadratic curve, appropriate correction can always be performed regardless of the projection angle.

  Even if the correctable range (angle) by the lens shift function and the correctable range (angle) by the keystone correction function are set, if these functions are independent of each other, both are used. However, the correctable range is not the sum of the angles and can only be used in a narrower range. However, in the present invention, the parameters related to all the correction functions are reflected in equation (1) to match the correction functions. As a result, the correctable range can be corrected up to an angle substantially coincident with the sum of the angles.

  By configuring the projector 10 as in the first embodiment, the keystone correction, which is a correction unit using image processing, can be matched with the lens shift, which is a correction unit using an optical system. As described above, the keystone correction is accompanied by a certain degree of image quality deterioration, whereas the lens shift correction has little image quality deterioration, and it is preferable to use the lens shift correction as much as possible. Therefore, in the second embodiment, the projector 20 is configured as shown in FIG. 2, and the keystone correction can be performed only after the correction by the lens shift is performed to the limit. In FIG. 2, the same components as those in FIG.

  In FIG. 2, the video signal from the video signal input terminal 11 and an output signal obtained by performing image processing in the keystone correction unit 12 on the video signal from the video signal input terminal 11 are input to the selection unit 21. A signal for selecting one of the two signals input from the control unit 22 is input. The control unit 22 determines whether or not the lens movement amount has reached a limit value from the input lens position information, and if it has reached the limit value, selects the output from the keystone correction unit, When the limit value has not been reached, a signal for selecting the input video signal is output to the selection unit, and the selection unit 21 receives a selection signal when the lens movement amount is equal to or less than the limit value. Then, the video signal itself is output to the display element 13 at the subsequent stage, and when the selection signal when the lens movement amount reaches the limit value is input, the output of the keystone correction unit 12 is output to the display element 13 at the subsequent stage. Output.

With such a configuration, keystone correction cannot be performed unless correction by lens shift reaches a limit value, or even if it is performed, this cannot be reflected in the video display on the screen 15. Thus, the user can preferentially use correction by lens shift, which is a correction method with little deterioration in image quality. In the second embodiment, has been to select the output by providing a selector 21, without providing the selector 21, the control unit 17 in the configuration of FIG. 1, a lens movement amount L _x and L It is determined whether or not _y is a limit value, and only when the limit value is reached, an input of a keystone adjustment signal from the keystone adjustment signal input terminal 19 to the control unit 22 is received, and this received keystone correction is related. The same effect can be obtained by outputting θ and φ as parameters to the keystone correction unit 12.

In the second embodiment, the correction effect by the keystone correction cannot be reflected on the video unless the correction by the lens shift reaches the limit value. However, the present invention is not limited to this. For example, when the keystone correction is performed in a state where the correction by the lens shift has not reached the limit value, the user may be alerted. In this case, the control unit 17 (22) determines whether or not the lens movement amounts L _x and L _y are limit values. If the keystone correction is to be performed without the limit values, the control unit 17 By displaying on the liquid crystal display portion for operation in accordance with the command from (22), it is possible to adopt a method such as calling attention to the user.

1 is a block diagram showing a configuration of a projector 10 according to the present invention. It is the block diagram which showed the structure of the projector 20 by the other Example of this invention. It is the schematic diagram explaining the various parameters regarding the correction | amendment by the optical system of this invention. (A) is the schematic diagram explaining the projection angle (theta) which is a parameter regarding keystone correction | amendment, (b) is the schematic diagram explaining the projection angle (phi) which is a parameter regarding keystone correction | amendment. It is the schematic diagram explaining the distortion of the image at the time of projecting an image | video from the diagonal direction with respect to a screen. It is the schematic diagram demonstrated about the case where an image | video is translated using a lens shift function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Projector, 11 ... Video signal input terminal, 12 ... Keystone correction | amendment part, 13 ... Display element, 14 ... Projection lens, 15 ... Screen, 16 ... Signal input terminal for lens shift adjustment, 17 ... Control part, 18 ... Lens drive , 19 ... Keystone adjustment signal input terminal, 20 ... Projector, 21 ... Selection unit, 22 ... Control unit.

Claims (5)

  A keystone correction unit that performs image processing by keystone correction on an input video signal, a display element that displays an image based on an output signal from the keystone correction unit, and an image displayed on the display element from a light source A projection lens that projects light onto the screen using the light of the lens, a lens driving unit that moves the projection lens and outputs lens position information, parameters used for keystone correction, and a lens input from the lens driving unit And a control unit that outputs position information to the keystone correction unit. The control unit determines whether or not the lens movement amount has reached a limit value from the input lens position information. Only when the movement amount has reached the limit value, input the keystone adjustment signal that changes the parameter used for keystone correction. Projector, characterized in that so as to output the keystone correction unit put.   In the control unit, it is determined whether or not the lens movement amount has reached a limit value from the input lens position information, and if the limit value has been reached, the output from the keystone correction unit is selected, 2. The projector according to claim 1, wherein an input video signal is selected when the limit value is not reached.   The control unit includes means for determining whether or not the lens movement amount has reached a limit value from the input lens position information, and when the lens movement amount has not reached the limit value, the keystone correction is performed. And a means for outputting a signal notifying that the lens movement amount has not reached the limit value when a keystone adjustment signal changing the parameter used for the lens is input. The projector according to claim 1 or 2. A keystone correction unit that performs image processing by keystone correction on an input video signal, a display element that displays an image based on an output signal from the keystone correction unit, and an image displayed on the display element from a light source A projection lens that projects light onto the screen using the light of the lens, a lens driving unit that moves the projection lens and outputs lens position information, parameters used for keystone correction, and a lens input from the lens driving unit And a control unit that outputs position information to the keystone correction unit, and parameters used for the keystone correction include vertical tilt θ of the projection angle, horizontal tilt φ of the projection angle, and between the light source and the display element. 1 and the distance L between the light source and the screen, and the lens position information output from the lens driving unit In the keystone correction unit, the pixel position (x, y) on the display element and the display position (X, Y) on the screen are assumed to be the horizontal movement amount L _x and the vertical movement amount L _y. And a projector having the relationship of the following formula (1) to perform image processing by keystone correction.

The parameters used for the keystone correction are the vertical tilt θ of the projection angle, the horizontal tilt φ of the projection angle, the distance l between the light source and the display element, and the distance L between the light source and the screen. The lens position information output from the driving unit is assumed to be a horizontal movement amount L _x and a vertical movement amount L _y of the lens. In the keystone correction unit, the pixel position (x, y on the display element) is assumed. And the display position (X, Y) on the screen have the relationship of the following expression (1), image processing by keystone correction is performed.

Images