JP2007019654A - Projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a projector capable of executing optimum Keystone correction by estimating a lens position. <P>SOLUTION: The projector is provided with a Keystone corrector for performing image processing based on Keystone correction for an input video signal, a display element for displaying a video image on the basis of an output signal from the Keystone correction, a projection lens for projecting the displayed video image on a screen by using a light from a light source, a lens driver for moving this projection lens, and a control unit for outputting a parameter to be used for Keystone correction to the Keystone correction section. In the projector, the control unit stores the original position of a lens, stores the movement quantity of the lens of each direction when the lens is moved from the original position to the limit position to which the lens can move from this position in each of a plurality of directions, determines the direction of the lens in the plurality of lens directions by using the parameter of a projection angle to be used in the Keystone correction, and reads the lens movement quantity corresponding to this direction and outputs it to the Keystone correction section. <P>COPYRIGHT: (C)2007,JPO&INPIT

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.

  Further, in Patent Document 1, a configuration in which the lens shift amount is detected by the encoder 35 is adopted, and the detection result is supplied to the microcomputer 21, and the microcomputer 21 creates data on the lens shift amount. The distortion correction circuit 31 is used for distortion correction. By adopting a configuration that detects the lens shift amount in this way, it becomes possible to match the correction of both the optical system and the image processing system, but on the other hand, control such as detection and calculation is performed every time the lens shift is performed. There was a problem that the burden of control will become large.

  The present invention has been made in view of the above problems, and an object thereof is to provide a projector capable of estimating a lens position and performing an optimum keystone correction without providing a mechanism for detecting a lens position. Is.

  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 a control unit that outputs parameters used for keystone correction to the keystone correction unit, The control unit stores the origin position of the lens, and stores the amount of lens movement in each direction when the lens is moved from the origin position to a limit position that can be moved in a plurality of directions. Then, using the projection angle parameter used for keystone correction, determine which direction is a plurality of lens position directions, A projector is characterized in that so as to output to the keystone correction unit reads out the lens movement amount corresponding to the direction of.

  In addition to claim 1, the lens position direction of the present invention is set to the eight directions of the upper, lower, left, right, upper left, upper right, lower left and lower right in addition to the origin position. This is a projector characterized by.

  The third aspect of the present invention, in addition to the first aspect, stores, as the lens movement amount in each direction, movement amounts for a plurality of locations in the middle in addition to the movement amount to the limit position. The projector is characterized in that any one of a plurality of lens movement amounts can be selected.

  According to the first aspect of the present invention, the control unit stores the origin position of the lens, and the amount of lens movement in each direction when the lens is moved from the origin position to a limit position that can be moved in a plurality of directions. Is stored, and the projection angle parameter used in the keystone correction is used to determine which of the plurality of lens position directions, and the lens movement amount corresponding to this direction is read out to the keystone correction unit. Since the output is performed, the optimum keystone correction can be performed by estimating the lens position without providing a mechanism for detecting the lens position.

  According to the second aspect of the invention, the lens position direction is stored in the control unit as the eight directions of the upper, lower, left, right, upper left, upper right, lower left, and lower right in addition to the origin position. Since the lens movement amount corresponding to one of the directions is read and used, the mechanism for grasping the current position of the lens is omitted, thereby reducing the control burden and reducing the cost. Even if the lens position cannot be grasped, the correction is performed by assuming the lens position from the keystone correction parameter, so the mechanism for grasping the current position of the lens is omitted. It is possible to realize equivalent correction.

  According to the third aspect of the present invention, as the lens movement amount in each direction, in addition to the movement amount to the limit position, movement amounts for a plurality of locations in the middle are stored, and the plurality of lens movement amounts are stored. Since either one can be selected, it is not limited to the eight directions moved to the limit position. For example, 16 directions including the intermediate position are memorized, and it is possible to select and select more appropriately. It is possible to estimate the correct lens position.

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 A projection lens that projects the projected image onto the screen using light from the light source, a lens driving unit that moves the projection lens, and a control unit that outputs parameters used for keystone correction to the keystone correction unit When the control unit stores the origin position of the lens and moves the lens from the origin position to the limit position in each of eight directions of up, down, left, right, upper left, upper right, lower left, and lower right. Each lens movement amount is stored separately, and the projection angle, which is a parameter determined with the keystone correction operation, is tilted in the vertical direction. It is determined that the projection direction is one of the eight directions using θ and the horizontal inclination φ, and the lens movement amount corresponding to this direction is read out and output to the keystone correction unit. It is a feature.
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 movement amount instruction signal is input to the control unit 17 from the lens movement amount instruction 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 a lens movement amount instruction signal based on the operation performed by the user is described later. Output to the lens driving unit 18. 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 lens movement amount based on the lens movement amount instruction signal is not used as a parameter relating to lens shift in the calculation of correction processing performed by the keystone correction unit 12, but is used exclusively for lens driving by the lens driving unit 18. In the calculation of the correction process performed by the keystone correction unit 12, parameters relating to lens shift stored in advance by the control unit 17 are used based on conditions described later.

  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. 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.

Next, parameters relating to the lens position, which are parameters stored in the control unit 17, 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. It shall be 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, the lens moves as shown in FIG. By doing so, the center o of the display element 13 is relatively moved. At this time, the movement amount in the x direction of the lens with respect to the reference point (for example, the center o of the display element 13) is L _x, and the movement amount in the y direction is L _y .

As described above, in the present invention, the lens position is indicated by the movement amount of the lens in the x direction and the movement amount in the y direction. However, as described above, in the present invention, the lens position is detected. The lens movement amount is not stored, and the lens moves each time in response to the lens movement amount instruction signal. However, a mechanism for grasping the current position of the lens is not provided. Instead, the lens movement amount with respect to the reference point when the lens movement reaches the limit is stored, and this is read out and used for correction when performing keystone correction. For example, as shown in FIG. 2, the lens movement direction when the lens is at the center is stored as L0, and the lens movement directions when moving from the position of L0 to the limit in eight directions are stored as L1 to L8. These are read out under the conditions described later, assuming that one of them is the current lens movement direction, and used as a keystone correction parameter. The lens movement directions L1 to L8 stored here are stored as a combination of the movement amount in the x direction and the movement amount in the y direction as (L _1x , L _1y ) to (L _8x , L _8y ), respectively. Is done.

The keystone correction unit 12 receives the projection angles θ and φ, which are parameters related to the keystone correction function, and reads out one of the lens movement directions L0 to L8 stored in the control unit 17. Entered. 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 commonly 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, projector arrangement and lens shift operation performed as a pre-stage of keystone correction will be described. First, when the user projects an image on the screen, it is most preferable to project the image from the front of the screen, but it is not always possible to place the image on the front. In such a case, the projector is arranged at a position deviated from the front while maintaining the projection angle perpendicular to the screen, and then the lens shift function is used to translate the image to the center of the screen. Display. If the image cannot be displayed at the target position even if the image is translated using this lens shift function, the selection is made to project the image from the oblique direction for the first time on the screen. If operation is performed in this flow, the lens shift is performed to shift the lens to the limit position, and then the image is projected from the oblique direction to the screen, so when keystone correction must be performed Unless the user performs an operation mistake, the possibility that the lens is shifted to the limit position in the same direction as the projection direction of the obliquely projected projector is extremely high.

  In the present invention, it is assumed that the user is operating according to the flow as described above, so that the amount of lens movement up to the limit position in any one direction is controlled in advance regardless of the current actual lens position. 17 is selected from the L1 to L8 stored in 17 and applied to the calculation in the keystone correction unit 12.

  Here, conditions for selecting any one of the lens movement directions L1 to L8 will be described. As described above, since it is highly likely that the lens is shifted to the limit position in the same direction as the projection direction of the obliquely projected projector, the projection angles θ and φ which are parameters for determining the projection direction are used. Select the lens movement amount. Specifically, of the vertical inclinations shown in FIG. 4A, θ when projecting upward is positive, and θ when projecting downward is negative, and FIG. 4B shows the negative θ. Of the inclinations in the horizontal direction shown, φ when projecting toward the right side is positive, φ when projecting toward the left side is negative, the projection direction of the projector is determined from these combinations, and the lens movement directions L1 to L1 are determined. A corresponding one of L8 is selected.

For example, when projecting upward as shown in FIG. 5B, it is estimated that the lens is shifted to the upper limit position. In this state, the user performs the keystone correction in the vertical direction to determine the projection angle θ. In this case, θ> 0, and correction in the horizontal direction is not necessary, so φ = 0. Therefore, when θ> 0 and φ = 0, it is assumed that the lens movement direction is L1 among the eight directions shown in FIG. 2, and this is output to the keystone correction unit 12. The other directions are also selected under the following conditions.
When θ = 0 and φ = 0, the lens moving direction = L0
When θ> 0 and φ = 0, the lens moving direction = L1
When θ <0 and φ = 0, the lens moving direction = L2.
When θ = 0 and φ> 0, the lens moving direction = L3
When θ = 0 and φ <0, the lens moving direction = L4
When θ> 0 and φ> 0, the lens moving direction = L5
When θ> 0 and φ <0, the lens moving direction = L6
When θ <0 and φ> 0, the lens moving direction = L7
When θ <0 and φ <0, the lens moving direction = L8

A flow of image processing performed in the keystone correction unit 12 based on the parameters input in this way 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.

  In the present invention, since the parameters related to all the correction functions are reflected in the above equation (1), even if both the keystone correction and the correction by the lens shift function are used together, a rectangle having a normal aspect ratio is obtained. Can be corrected. 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.

  Furthermore, in the present invention, the mechanism for grasping the current position of the lens is omitted, so that the control burden is reduced and the cost is reduced. Since the correction is performed by assuming the lens position from the correction parameters, the same correction can be realized even though the mechanism for grasping the current position of the lens is omitted.

  In the above-described embodiment, the sign of θ and φ is used as a condition for selecting one direction from eight directions that are candidates for the lens movement direction, but the present invention is not limited to this. For example, instead of determining with the boundary conditions of θ> 0, θ = 0, 0> θ, a certain constant a is set and the boundary conditions of θ> a, a ≧ θ ≧ −a, −a> θ are set. You may make it judge. In this case, the condition for selecting L1 in FIG. 2 is that if θ> a and a ≧ φ ≧ −a, the lens moving direction = L1. With this condition, even if the user makes a slight correction in the left-right direction during keystone correction, the lens moving direction is not changed as it is within a range smaller than the constant a, and the projection direction The possibility of selecting a different lens movement direction is reduced.

  In the above embodiment, as shown in FIG. 2, eight directions are assumed as the lens movement direction candidates, but the present invention is not limited to this, and more directions may be stored as candidates. Good. For example, one more may be added in the middle of each of the eight directions in FIG. 2 and 16 directions may be stored as candidates. As the setting of the selection condition in this case, for example, in addition to the positive and negative conditions of θ and φ, the absolute values of θ and φ may be compared and selected from the ratio.

1 is a block diagram showing a configuration of a projector 10 according to the present invention. FIG. 7 is a schematic diagram illustrating eight directions as candidates for lens movement directions stored in the control unit 17 of FIG. 1. 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 part, 13 ... Display element, 14 ... Projection lens, 15 ... Screen, 16 ... Lens shift movement amount instruction | indication input terminal, 17 ... Control part, 18 ... Lens drive , 19 ... Keystone adjustment signal input terminal.

Claims (3)

  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 the projection lens on the screen using the light, a lens driving unit that moves the projection lens, and a control unit that outputs parameters used for keystone correction to the keystone correction unit. The lens origin position is stored, and the lens movement amount in each direction when the lens is moved from the origin position to a limit position that can be moved in a plurality of directions is stored, and the projection angle used for keystone correction is stored. Is used to determine which of the multiple lens position directions, and the label corresponding to this direction. Projector, characterized in that so as to output to the keystone correction unit reads out's movement amount.   2. The projector according to claim 1, wherein the lens position direction includes eight directions of upper, lower, left, right, upper left, upper right, lower left, and lower right in addition to the origin position.   As the lens movement amount in each direction, in addition to the movement amount to the limit position, movement amounts for a plurality of locations in the middle are stored, and any one of the plurality of lens movement amounts can be selected. The projector according to claim 1.

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