JP2015185985A - Projector and projector control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projector capable of executing a trapezoidal distortion correction method corresponding to the correction amount of trapezoidal distortion correction.SOLUTION: The projector comprising image projection means and trapezoidal distortion correction means for executing trapezoidal distortion correction corresponding to a correction amount executes first trapezoidal distortion correction(S104), when the correction amount does not exceed a threshold (S103: N); and executes second trapezoidal distortion correction (S107) when the correction amount exceeds the threshold (S103: Y).

Description

  The present invention relates to a projector and a projector control method.

In a projector that projects an image on a projection surface such as a screen, the projected image is distorted when the installation position of the projector is not directly facing the projection surface (projection distortion). For example, when tilt projection is performed with the projector tilted vertically or horizontally with respect to the screen, a phenomenon (trapezoidal distortion) occurs in which an image displayed on the projection surface is distorted in a trapezoidal shape. For this reason, as in Patent Document 1, there is known a projector that corrects a projected image (keystone distortion correction) by forming an image distorted so as to cancel the trapezoidal distortion when forming an image with a light modulation device. ing.

JP-A-9-261568 JP 2008-277753 A

In such a trapezoidal distortion correction, the length of the projected image in the direction orthogonal to the tilt direction (the width of the image when projecting upward in the tilt direction) is reduced toward the tilt direction, and the tilt direction The pixels of the light modulation device are thinned out so that the length of the projected image in the direction parallel to (the height of the image in the case of projecting upward) maintains the aspect ratio of the original image. That is, there is a problem that as the tilt amount is larger and the correction amount for correcting the keystone distortion is larger, the information of the original image is lost and the image quality of the projected image is deteriorated.
Patent Document 2 discloses a projector that suppresses missing pixel data by reducing an image only in one direction at the time of correcting trapezoidal distortion and not maintaining the aspect ratio of the image. However, since the aspect ratio is not maintained, the projection image may be greatly deformed depending on how the user uses it.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

Application Example 1 A projector according to this application example includes a light source, a light modulation device that modulates light emitted from the light source according to input image data, and image light modulated by the light modulation device. A projector having image projection means for projecting as a projected image on a projection surface, wherein the light modulation device reduces or enlarges the image data based on a correction amount for correcting trapezoidal distortion that occurs when tilt projection is performed. A trapezoidal distortion correction means for correcting the trapezoidal distortion, the trapezoidal distortion correction means, the length of the image data in the direction orthogonal to the tilt direction,
In accordance with the correction amount, the first trapezoidal distortion correction is performed such that the image data is reduced in the tilt direction and the length of the image data in the direction parallel to the tilt direction is reduced in accordance with the correction amount. A second trapezoidal distortion correction that reduces the length of the image data to a predetermined length, and reduces the length of the image data in the direction orthogonal to the tilt direction toward the tilt direction according to the correction amount; When the correction amount does not exceed a predetermined threshold, the first trapezoidal distortion correction is executed, and when the correction amount exceeds the predetermined threshold, the second trapezoidal distortion correction is executed. .

According to this application example, the length of the image data in the direction parallel to and perpendicular to the tilt direction is reduced in accordance with the correction amount within a range where the correction amount of the trapezoidal distortion correction in the tilt projection does not exceed the predetermined threshold. When trapezoidal distortion correction is performed and the correction amount exceeds the threshold, the length of the image data in the direction parallel to the tilt direction is reduced to a predetermined length, and the length of the image data in the direction orthogonal to the tilt direction is set as the correction amount. A second trapezoidal distortion correction that is reduced accordingly is performed. That is, when the correction amount of the trapezoidal distortion correction does not exceed the predetermined threshold, the aspect ratio of the image data is retained by the first trapezoidal distortion correction, and when the correction amount exceeds the threshold, the second trapezoidal distortion correction causes the image data of the image data to be corrected. Although the aspect ratio is not maintained, loss of image data due to trapezoidal distortion correction can be suppressed.

Application Example 2 In the projector according to the application example described above, a notification unit is further provided, and the notification unit performs correction performed by the trapezoidal distortion correction unit from the first trapezoidal distortion correction to the second.
When changing to keystone distortion correction, it is preferable to notify.

According to this application example, when the correction amount exceeds a predetermined threshold value, a notification is made when the trapezoidal distortion correction method switches from the first trapezoidal distortion correction to the second trapezoidal distortion correction. It is possible to notify and prompt the user to review the installation position of the projector when it is desired to correct the first trapezoidal distortion.

Application Example 3 In the projector according to the application example, it is preferable that the projector further includes an input operation unit that receives an operation for setting the correction amount.

According to this application example, the user sets the correction amount of the trapezoidal distortion correction by the input operation unit, and the first
It becomes possible to execute trapezoidal distortion correction or second trapezoidal distortion correction.

Application Example 4 In the projector according to the application example described above, the trapezoidal distortion correction unit changes the threshold value when a predetermined operation by the input operation unit is received, the threshold value after the change, and the correction amount Preferably, the first trapezoidal distortion correction or the second trapezoidal distortion correction is executed.

According to this application example, since the threshold value for switching from the first trapezoidal distortion correction to the second trapezoidal distortion correction can be changed, the threshold value is changed after confirming the corrected projected image, and the changed threshold value and According to the correction amount, it becomes possible to execute the trapezoidal distortion correction by switching the correction method.

Application Example 5 In the projector according to the application example described above, it is preferable that the projector further includes an angle detection unit that detects an installation angle of the projector, and the correction amount is set based on the detected installation angle.

According to this application example, it is possible to set the correction amount of the trapezoidal distortion correction according to the installation angle of the projector detected by the angle detection unit, and to execute the first trapezoidal distortion correction or the second trapezoidal distortion correction.

Application Example 6 In the projector according to the application example described above, the trapezoidal distortion correction unit reduces the length of the image data in a direction parallel to the tilt direction to a predetermined length, and in a direction orthogonal to the tilt direction. And a third trapezoidal distortion correction that increases the length of the image data in a direction opposite to the tilt direction according to the correction amount, and the trapezoidal distortion correction means, when the correction amount exceeds the predetermined threshold, It is preferable to execute the third trapezoidal distortion correction instead of the second trapezoidal distortion correction.

According to this application example, when the correction amount of the trapezoidal distortion correction exceeds the threshold value, instead of the second trapezoidal distortion correction, the length of the image data in the direction parallel to the tilt direction is reduced to the predetermined length, and the tilt direction The third trapezoidal distortion correction is executed to enlarge the length of the image data in the direction orthogonal to the direction corresponding to the correction amount. As a result, when the correction amount exceeds the threshold value, there is no missing pixel thereafter, so that it is possible to prevent image quality deterioration of the projected image data.

Application Example 7 A projector control method according to this application example is obtained by modulating a light source, a light modulation device that modulates light emitted from the light source according to input image data, and the light modulation device. A method of controlling a projector having image projection means for projecting image light onto a projection surface as a projection image, a correction amount setting step for setting a correction amount for correcting trapezoidal distortion that occurs when tilt projection is performed, The length of the image data in the direction orthogonal to the direction is reduced according to the correction amount, and the length of the image data in the direction parallel to the tilt direction is reduced according to the correction amount. A trapezoidal distortion correction step, the length of the image data in the direction parallel to the tilt direction is reduced to a predetermined length, and the length of the image data in the direction orthogonal to the tilt direction is adjusted according to the correction amount. A second trapezoidal distortion correction step for reducing the tilt toward the tilt direction, and when the correction amount does not exceed a predetermined threshold, the first trapezoidal distortion correction step is executed, and the correction amount exceeds the predetermined threshold Has a control step for executing the second trapezoidal distortion correction step.

According to this application example, the length of the image data in the direction parallel to and perpendicular to the tilt direction is reduced in accordance with the correction amount within a range where the correction amount of the trapezoidal distortion correction in the tilt projection does not exceed the predetermined threshold. Execute the trapezoidal distortion correction step, and if the correction amount exceeds the threshold, the length of the image data in the direction parallel to the tilt direction is reduced to a predetermined length, and the length of the image data in the direction orthogonal to the tilt direction is corrected A second trapezoidal distortion correction step for reducing the amount according to the amount is executed. That is, when the correction amount of the trapezoidal distortion correction does not exceed the predetermined threshold, the aspect ratio of the image data is retained by the first trapezoidal distortion correction, and when the correction amount exceeds the threshold, the second trapezoidal distortion correction causes the image data of the image data to be corrected. Although the aspect ratio is not maintained, loss of image data due to trapezoidal distortion correction can be suppressed.

1 is a block diagram showing a circuit configuration of a projector according to an embodiment. The front view which shows a liquid crystal light valve. The top view of a remote controller. Explanatory drawing which shows the principle of the installation angle detection of a projector. Explanatory drawing for demonstrating trapezoid distortion. Explanatory drawing for demonstrating trapezoid distortion correction. Explanatory drawing for demonstrating the transition of trapezoid distortion correction. The flowchart which shows operation | movement of a projector.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. However, the following embodiment does not limit the invention according to the scope of claims, and all combinations of features in the embodiment are based on the invention. It is not always essential to the solution.

(Embodiment)
FIG. 1 is a block diagram illustrating a circuit configuration of the projector 1 according to the present embodiment.
As shown in FIG. 1, the projector 1 includes an image input terminal 6, an image projection unit 10, a trapezoidal distortion correction unit 15, an OSD processing unit 16, an image signal processing unit 17, an image signal input unit 18, an angle detection unit 19, and a control. Means 20, storage means 21, light source control means 22, main body operation means 23,
It comprises an operation signal receiving means 24, a remote controller (remote controller) 25, a power supply terminal 30, a power supply unit 31, an informing means 40, etc., and these are housed inside or outside the casing (not shown).

The image projection means 10 includes a light source 11 and three liquid crystal light valves 12R as light modulators.
12G, 12B, a projection lens 13 as a projection optical system, liquid crystal driving means 14 and the like. The image projection means 10 converts the light emitted from the light source 11 into liquid crystal light valves 12R and 12G.
, 12B, and the projected image is projected from the projection lens 13 to display a projected image on a projection surface such as the screen SC.

The light source 11 includes a discharge-type light source lamp 11a made of an ultra-high pressure mercury lamp, a metal halide lamp, or the like, and a reflector 11b that reflects light emitted from the light source lamp 11a toward the liquid crystal light valves 12R, 12G, and 12B. ing.
Light emitted from the light source 11 is converted into light having a substantially uniform luminance distribution by an integrator optical system (not shown), and red (R), which is the three primary colors of light, by a color separation optical system (not shown),
After being separated into green (G) and blue (B) color light components, the liquid crystal light valve 12R respectively.
, 12G, 12B.

FIG. 2 is a front view showing the liquid crystal light valves 12R, 12G, and 12B. The liquid crystal light valves 12R, 12G, and 12B are configured by a liquid crystal panel in which liquid crystal is sealed between a pair of transparent substrates. As shown in FIG. 2, on the inner surface of each transparent substrate, a transparent electrode (pixel electrode) capable of applying a driving voltage to the liquid crystal for each minute region (pixel 12p) is a rectangular region (pixel region 1).
2a) is formed in a matrix.

When the liquid crystal driving unit 14 applies a driving voltage corresponding to the input image data to each pixel 12p, each pixel 12p is set to a light transmittance corresponding to the image data. For this reason, the light source 11
The light emitted from the light is modulated by transmitting through the liquid crystal light valves 12R, 12G, and 12B, and image light corresponding to the image data is formed for each color light.
The formed image light of each color is synthesized for each pixel by a color synthesis optical system (not shown) to become color image light, and then enlarged and projected onto the screen SC or the like by the projection lens 13 to become a projection image.

In the present embodiment, the projector 1 that projects using the light source lamp 11a as the light source is exemplified. However, the present invention is also applicable to a projector that projects using a light emitting diode (LED) light source or a laser light source as the light source. Can do.

In the present embodiment, the image projection unit 10 includes three liquid crystal light valves 12R and 12G.
, 12B is used as an example, but a light modulation device of another display system such as a reflective liquid crystal display system or a micromirror device system (light switch display system) may be employed. .

Returning to FIG. 1, the control means 20 includes a CPU (Central Processing Unit) (not shown), a RAM (Random Access Memory) used for temporary storage of various data, and the like, and a control program stored in the storage means 21 ( The overall operation of the projector 1 is controlled by operating according to (not shown). That is, the control unit 20 functions as a computer together with the storage unit 21.

The storage means 21 is composed of a rewritable nonvolatile memory such as a flash memory or FeRAM (Ferroelectric RAM). The storage unit 21 stores a control program for controlling the operation of the projector 1, various setting data for defining operation conditions of the projector 1, and the like. In the present embodiment, the storage unit 21 stores trapezoidal distortion correction information 21a. The trapezoidal distortion correction information 21a includes trapezoidal distortion correction direction (vertical direction, horizontal direction), trapezoidal distortion correction amount S, trapezoidal distortion correction method (first trapezoidal distortion correction, second trapezoidal distortion correction, third Trapezoidal distortion correction), and a threshold value L of the correction amount S for switching the correction method. The trapezoidal distortion correction unit 15 performs trapezoidal distortion correction on the projected image based on the trapezoidal distortion correction information 21a. The correction amount S is set based on the operation by the main body operating means 23 and the remote controller 25 or the detection result detected by the angle detecting means 19. The threshold L is set by operating the main body operating means 23 or the remote controller 25.

The main body operation means 23 is provided in a housing (not shown) of the projector 1 and includes a plurality of operation keys for giving various instructions to the projector 1. The main body operating means 23 has operation keys equivalent to the operation keys provided in the remote controller 25 described later. When the user operates various operation keys of the main body operation means 23, the main body operation means 23 outputs an operation signal corresponding to the operation content of the user to the control means 20.

The remote controller 25 includes operation keys equivalent to the main body operating means 23 and gives various instructions to the projector 1.
FIG. 3 is a plan view of the remote controller 25. As shown in FIG. 3, the remote controller 25 has a power key 25a for switching on / off alternately, an input switching key 25b for switching a plurality of image input terminals 6, and menu settings for performing various settings. A menu key 25c for displaying an image or the like, a cursor key 25d (four operation keys corresponding to up, down, left, and right) used for selecting a setting item in a menu setting image or the like, and a determination key for confirming the selected setting item 25e, an escape key 25f for canceling the operation, etc., a trapezoidal distortion correction key 25g for setting a correction amount S for trapezoidal distortion correction, and the like. The threshold value L of the correction amount S is set by operating the menu key 25c, the cursor key 25d, or the like.
When the user operates various operation keys of the remote controller 25, the remote controller 25 generates an operation signal such as an infrared ray corresponding to the operation content of the user, and the operation signal receiving unit 24 receives this and transmits it to the control unit 20.

Returning to FIG. 1, the operation signal receiving unit 24 is configured to include an infrared receiving unit and the like, and the remote controller 2.
The operation signal issued from 5 is received and transmitted to the control means 20 as control information. The main body operating means 23, the remote controller 25, and the operation signal receiving means 24 correspond to input operating means.

The angle detection unit 19 includes an acceleration sensor 19a (see FIG. 4) and the like, and detects the installation angle of the projector 1 based on an instruction from the control unit 20. Then, the detected installation angle is notified to the control means 20.

Here, a method for detecting the installation angle of the projector 1 will be described. FIG. 4 is an explanatory diagram showing the principle of installation angle detection of the projector 1. This figure is a diagram showing the projector 1, its installation surface H, and the screen SC from the side. The installation surface H is assumed to be horizontal. In the present embodiment, the acceleration sensor 19a is used to detect the installation angle of the projector 1.
Is used. The acceleration sensor 19a is mounted inside the projector 1, and detects the gravitational acceleration acting along the axis 1a extending in the front-rear direction of the projector 1, as shown in FIG.

When the projector 1 is installed horizontally with respect to the installation surface H, the gravitational acceleration to the acceleration sensor 19a acts in the vertically downward direction. For this reason, since gravitational acceleration does not occur in the direction along the axis 1a (the front-rear direction of the projector 1), the output of the acceleration sensor 19a becomes zero.
On the other hand, as shown in FIG. 4, when the projector 1 is installed with an installation angle θ with respect to the installation surface H, the gravitational acceleration component in the direction along the axis 1 a is g as shown in the figure.・ Si
nθ. The acceleration sensor 19a outputs a voltage corresponding to the gravitational acceleration component. Thereby, the angle detection means 19 can detect the installation angle of the projector 1 based on the voltage value output from the acceleration sensor 19a.
In the present embodiment, the angle detection unit 19 is configured using the acceleration sensor 19a. However, the mechanism is not limited to the acceleration sensor 19a as long as the mechanism can detect the installation angle of the projector 1.

Returning to FIG. 1, the light source control unit 22 controls the supply and stop of power to the light source 11 based on an instruction from the control unit 20, and switches on and off the light source 11.

The image signal input means 18 receives image data from a plurality of image input terminals 6 from an external image output device such as a video reproduction device or a personal computer via a cable (not shown) or a communication device. The input image data is based on an instruction from the control unit 20.
It is output to the image signal processing means 17. Note that the image signal input unit 18 may include a receiving unit for wireless communication, optical communication, or the like, and input an image signal wirelessly from an external device.

The image signal processing unit 17 converts the image data input from the image signal input unit 18 into image data representing the gradation of each pixel of the liquid crystal light valves 12R, 12G, and 12B based on an instruction from the control unit 20. Here, the converted image data is red (R), green (G), blue (B
) And is composed of a plurality of pixel values corresponding to all pixels of the liquid crystal light valves 12R, 12G, and 12B. The pixel value defines the light transmittance of the corresponding pixel, and the intensity (gradation) of light transmitted through each pixel and emitted is defined by this pixel value.

The OSD processing unit 16 performs processing for superimposing and displaying an OSD (on-screen display) image such as a menu image or a message image on the projection image based on an instruction from the control unit 20. The OSD processing means 16 includes an OSD memory (not shown)
OSD image data representing graphics, fonts, and the like for forming a D image is stored.

When the control means 20 instructs to superimpose the OSD image, the OSD processing means 16 reads the necessary OSD image data from the OSD memory, and outputs an image signal so that the OSD image is superimposed at a predetermined position on the projected image. The OSD image data is synthesized with the image data input from the processing means 17. The image data combined with the OSD image data is output to the trapezoidal distortion correction means 15.
If there is no instruction to superimpose the OSD image from the control unit 20, the OSD processing unit 16 outputs the image data input from the image signal processing unit 17 to the trapezoidal distortion correction unit 15 as it is.

The trapezoidal distortion correcting unit 15 suppresses distortion (trapezoidal distortion) that causes the projected image to expand in the tilt direction (tilt direction) when an image is projected with the projector 1 tilted with respect to the screen SC. The input image data is corrected (keystone distortion correction). Main body operating means 23
Alternatively, based on the information on the trapezoidal distortion correction instruction input from the remote controller 25 and the information on the installation angle of the projector 1 detected by the angle detection unit 19, the control unit 20 performs the trapezoidal distortion correction unit 1.
5 is instructed to perform the trapezoidal distortion correction, and the trapezoidal distortion correction means 15 performs the trapezoidal distortion correction. As will be described in detail later, the trapezoidal distortion correction means 15 performs three types of trapezoidal distortion correction, namely, a first trapezoidal distortion correction, a second trapezoidal distortion correction, and a third trapezoidal distortion correction.

Trapezoidal distortion correction is to thin out or add pixel values from image data and reduce the projected image toward the tilt direction, or enlarge the projected image toward the opposite direction of the tilt direction. The trapezoidal distortion correcting unit 15 outputs the corrected image data to the liquid crystal driving unit 14.
Note that when the keystone distortion correction is not performed, the image data output from the OSD processing unit 16 is output to the liquid crystal driving unit 14 as it is.

The liquid crystal driving means 14 receives the image data input from the OSD processing means 16, that is, the pixel 12p.
When the liquid crystal light valves 12R, 12G, and 12B are driven according to each pixel value, an image corresponding to the image data is projected from the projection lens 13, and a projected image is displayed on the projection surface of the screen SC.

The power supply unit 31 is supplied with electric power such as AC 100V from the outside via the power supply terminal 30.
The power supply unit 31 converts input power (AC power) into predetermined DC power and supplies the power to each unit of the projector 1. In addition, the power supply unit 31 stops supplying power (operating power) necessary for image projection to each unit (power-on state) and operating power supply based on an instruction from the control unit 20. It is possible to switch between a state (standby state) of waiting for an operation for turning on.

The notification unit 40 is configured by an LED, a buzzer, or the like, and notifies when the correction performed by the trapezoidal distortion correction unit 15 is switched from the first trapezoidal distortion correction to the second trapezoidal distortion correction.

Next, the trapezoidal distortion correction by the trapezoidal distortion correcting unit 15 will be described with reference to FIGS. 5, 6, and 7. FIG.
FIG. 5 is an explanatory diagram for explaining trapezoidal distortion, and is a diagram for explaining a case where keystone distortion correction is not performed on image data. Here, FIG. 6A shows the liquid crystal light valve 12.
A front view of R, 12G, and 12B as viewed from the light incident surface side, FIG. 5B is a side view showing how the projector 1 performs horizontal projection, and FIG. It is a front view which shows the projection image displayed. FIG. 4D is a side view showing a state in which the projector 1 is projected in a tilted state, and FIG. 4E is a front view showing a projected image displayed on the screen SC at that time. is there.

In FIG. 5, in the left-right direction toward the liquid crystal light valves 12R, 12G, 12B (
The horizontal direction (left and right) is the ± x direction, the vertical direction (vertical vertical) is the ± y direction, and the horizontal direction (horizontal horizontal) toward the screen SC is the ± X direction and vertical direction (vertical vertical). Is the ± Y direction. Here, the X direction and the Y direction of the screen SC correspond to the x direction and the y direction of the liquid crystal light valve 12, respectively. For example, the pixels on the upper right (+ x, + y side) of the pixel region 12a are transmitted. The light is projected on the upper right (+ X, + Y side) of the screen SC.

In FIG. 5, the lattice pattern shown in the pixel area 12a and the projected image Ga is auxiliary to show the correspondence between the image formed in the pixel area 12a and the projected image Ga projected on the screen SC. It is a line added automatically, and does not mean that such a pattern is actually displayed.

As shown in FIG. 5A, when the keystone distortion correction is not performed, the liquid crystal light valve 12R,
12G and 12B form an image (input image) based on the image data input from the trapezoidal distortion correcting means 15 over the entire pixel region 12a. That is, in this case, the area for forming the input image (image forming area 12i) coincides with the pixel area 12a. Here, FIG.
, (C), when the projector 1 is installed horizontally and performs projection with no inclination on the screen SC, the display image Gi (projected image Ga) displayed on the screen SC is displayed.
) Has the same rectangular shape as the pixel region 12a.

On the other hand, as shown in FIGS. 5D and 5E, when the projector 1 is installed tilted with respect to the screen SC and projected upward (in the + Y direction), it is displayed on the screen SC. The display image Gi (projected image Ga) is enlarged in the ± X direction and the + Y direction and distorted into a trapezoidal shape as it goes in the tilt direction (+ Y direction).

As described above, trapezoidal distortion correction will be described by taking as an example a case where tilt projection (tilt projection) in the + Y direction (vertical direction) is performed.
FIG. 6 is an explanatory diagram for explaining the trapezoidal distortion correction. FIG. 6A shows the first trapezoidal distortion correction,
FIG. 6B is a front view of the liquid crystal light valves 12R, 12G, and 12B by the second trapezoidal distortion correction as viewed from the light incident surface side. FIG. 5B shows the first and second trapezoidal distortion corrections after A front view showing a display image Gi displayed on the screen SC when tilting projection is performed, and FIG.
The front view of the liquid crystal light valves 12R, 12G, and 12B by the third trapezoidal distortion correction as seen from the light incident surface side, FIG. 6D shows the screen SC when performing the tilt projection after the third trapezoidal distortion correction.
It is a front view which shows the display image Gi displayed on. In FIG. 6, the lattice pattern shown in the pixel region 12 a and the projected image Ga is a supplementary line as in FIG. 5.

The trapezoidal distortion correcting unit 15 performs pixel value decimation or pixel value insertion from the image data input from the OSD processing unit 16, and the projected image Ga is inclined in the tilt direction (+ Y direction) as compared with the case where correction is not performed. Correction is performed such that the smaller the head is, the smaller the head is, or the larger the head is in the direction opposite to the tilt direction.

First, FIG. 6A and FIG. 6B regarding the first trapezoidal distortion correction and the second trapezoidal distortion correction.
).
In the first trapezoidal distortion correction and the second trapezoidal distortion correction, as shown in FIG. 6A, in the pixel regions 12a of the liquid crystal light valves 12R, 12G, and 12B, trapezoidal shapes in opposite directions that can cancel the trapezoidal distortion. That is, the image forming region 12i having a shape in which the length of the image orthogonal to the tilt direction (hereinafter referred to as the lateral width) is reduced toward the tilt direction (+ y direction) is set. Further, the input image is formed in the image forming area 12i by reducing the image length (hereinafter referred to as “image height”) in the direction parallel to the tilt direction (± y direction).
The trapezoidal distortion correcting unit 15 corrects the image data so that the light transmittance of each pixel 12p included in the region 12n outside the image forming region 12i is minimized.

At this time, if the correction amount S does not exceed the threshold L, the image height is reduced as the correction amount S increases. This correction is the first trapezoidal distortion correction. When the correction amount S further increases and exceeds the threshold value L, the image height is fixed at a predetermined position, that is, the height at the time when the correction amount S is the threshold value L, and thereafter, the image forming area is changed according to the correction amount S. Only the width of 12i is reduced. This is the second trapezoidal distortion correction. That is, the first trapezoidal distortion correction is performed in a range where the correction amount S does not exceed the threshold L, and the second trapezoidal distortion correction is performed when the correction amount S exceeds the threshold L. The image height in the first trapezoidal distortion correction is not smaller than the height when the correction amount S is the threshold value L (hereinafter referred to as “threshold height h1”). Then, the image height in the second trapezoidal distortion correction is maintained at the threshold height h1. Note that “perpendicular to the inclination direction” is not limited to the crossing angle of only 90 °, and includes a case where the inclination angle is substantially orthogonal to the inclination direction.

As a result, as shown in FIG. 6B, the display image G shown in FIG.
Since the distortion of i is corrected and the region Gn in the projection image Ga corresponding to the region 12n is hardly irradiated with light, the display image Gi is projected in a regular shape (rectangular shape).
In the case of the first trapezoidal distortion correction, it is displayed on the screen SC while maintaining the aspect ratio of the original image data. In the case of the second trapezoidal distortion correction, with respect to the aspect ratio of the original image data, Although the ratio of the vertical direction to the horizontal direction is increased, the image is displayed on the screen SC as an image with little pixel value thinning. In order to compensate for the lack of gradation information associated with thinning out pixel values, it is desirable to correct the pixel values of the pixels adjacent to the thinning target pixel according to the thinned pixel values.

Next, the third trapezoidal distortion correction will be described with reference to FIGS. 6 (c) and 6 (d).
In the third trapezoidal distortion correction, as shown in FIG. 6C, the image forming area 12i cancels the trapezoidal distortion in the pixel areas 12a of the liquid crystal light valves 12R, 12G, and 12B, as in the first trapezoidal distortion correction. Possible substantially trapezoidal shape in the opposite direction, that is, the horizontal width is set so as to decrease toward the tilt direction (+ y direction), but the image height is fixed to the threshold height h1, and the horizontal width at the upper end is a correction amount. S is fixed to the width w1 when the threshold value is L. Then, the image forming area 12i is enlarged as the lateral width goes downward as the correction amount S becomes larger than the threshold value L. When the width of the enlarged image becomes larger than the width of the original image data, supplementary data is inserted.
Further, as shown in FIG. 6C, since supplementary data cannot be inserted outside the left and right corners of the pixel area 12a, the image forming area 12i is part of the long side of the trapezoid (FIG. c)
The regions c1 and c2) shown in FIG.

As a result, as shown in FIG. 6D, as in the first trapezoidal distortion correction and the second trapezoidal distortion correction, the distortion of the display image Gi shown in FIG. Region c in FIG.
The areas d1 and d2 corresponding to 1 and c2 are not projected but are cut from the display image Gi.
As described above, in the third trapezoidal distortion correction, as the image is enlarged, part of the image (regions d1 and d2) corresponding to the regions c1 and c2 is cut, but the original image data has margins in the regions d1 and d2. In the case of having a region, the observer who observes the image does not feel uncomfortable. Further, since the pixel value is not thinned out in an uncut region, it is possible to prevent deterioration in image quality.

Next, transition between the first trapezoidal distortion correction and the second trapezoidal distortion correction will be described with reference to FIG. FIG. 7 is a diagram showing a transition of trapezoidal distortion correction according to the correction amount S. The correction amount S is in the order of (a) to (e).
Becomes larger. In each of FIGS. 7A to 7E, the left diagram shows the image forming area 12i of the liquid crystal light valves 12R, 12G, and 12B, and the right diagram corresponds to the left diagram. It is a figure which shows the display image Gi displayed on the screen SC. FIGS. 7A to 7C are diagrams illustrating a state in which the first trapezoidal distortion correction is performed, and FIGS. 7D and 7E are diagrams illustrating a state in which the second trapezoidal distortion correction is performed.

As shown in FIGS. 7A to 7C, in the first trapezoidal distortion correction, the image height is reduced as the correction amount S increases. As a result, the display image Gi displayed on the screen SC.
Is an image in which the aspect ratio is maintained without changing the height h2.
Next, when the correction amount S increases and exceeds the threshold value L, as shown in FIGS.
The image height is fixed to the threshold height h1, and thereafter only the image width is reduced. As a result, the display image Gi is an image in which the aspect ratio is not maintained and the height is higher than the height h2.

When the threshold value L is changed, the height h1 in FIGS. 6 and 7 is also changed. For example, when the threshold value L is decreased, the second trapezoidal distortion correction is executed from when the correction amount S is small, that is, when the tilt amount of the tilt projection is small, and conversely, when the threshold value L is increased,
After the correction amount S becomes larger, that is, the second trapezoidal distortion correction is executed from a larger tilt amount.
Note that setting information indicating whether to execute the second trapezoidal distortion correction or the third trapezoidal distortion correction when the correction amount S exceeds the threshold value L is stored in the trapezoidal distortion correction information 21a.

Next, the operation of the projector 1 of the present embodiment will be described using the flowchart of FIG. FIG. 8 is a flowchart showing the operation when the projector 1 detects the change operation of the correction amount S and the operation when the change operation of the threshold value L is detected.

[Operation when a change of correction amount is detected]
As shown in FIG. 8, while the projector 1 is operating, the projector 1 detected by the operation of the main body operation means 23, the keystone distortion correction key 25g of the remote controller 25, or the angle detection means 19.
When an operation for changing the correction amount S due to a change in the installation angle is accepted (step S101), the process proceeds to step S102.

In step S102, the control unit 20 changes the correction amount S received in step S101, that is, the operation of the main body operation unit 23, the keystone distortion correction key 25g of the remote controller 25, or the projector 1 detected by the angle detection unit 19. A correction amount S of keystone distortion correction based on the installation angle is acquired, and the process proceeds to step S103. Step S102 corresponds to a correction amount setting step.

In step S103, the control means 20 checks whether or not the correction amount S acquired in step S102 exceeds a threshold value L. When the correction amount S exceeds the threshold value L (step S10
3: Y), the process proceeds to step S105. When the correction amount S does not exceed the threshold L (step S103: N), the process proceeds to step S104.

In step S104, the control unit 20 causes the trapezoidal distortion correcting unit 15 to execute the first trapezoidal distortion correction, and the process proceeds to step S108. Step S104 corresponds to a first trapezoidal distortion correction step.

In step S105, the control means 20 checks whether or not the trapezoid distortion correction executed immediately before by the trapezoid distortion correction means 15 is the first trapezoid distortion correction. When the trapezoidal distortion correction performed immediately before is the first trapezoidal distortion correction (step S105: Y), the process proceeds to step S106. When the trapezoidal distortion correction performed immediately before is not the first trapezoidal distortion correction (step S105: N), step S107 is performed.
Transition to.

In step S106, the control unit 20 notifies the notification unit 40 that the trapezoidal distortion correction is switched from the first trapezoidal distortion correction to the second or third trapezoidal distortion correction, and step S107.
Transition to. In this case, a confirmation message indicating that the correction method is changed may be projected by the image projection unit 10 instead of the notification by the notification unit 40. In this case, the image projection unit 10 corresponds to the notification unit.

In step S107, the control unit 20 causes the trapezoidal distortion correcting unit 15 to execute the second trapezoidal distortion correction or the third trapezoidal distortion correction, and the process proceeds to step S108. Step S107 is the second
This corresponds to the trapezoidal distortion correction step. Steps S102 to S107 correspond to control steps.

  In step S108, the operation flow is terminated and the original operation is returned.

[Operation when threshold change operation is detected]
As shown in FIG. 8, when an operation for changing the threshold value L by a predetermined operation of the main body operation unit 23 or the remote controller 25 is received (step S111), the control unit 20 changes the threshold value L based on the received operation (step S112). ), And the process proceeds to step S103. In addition, since operation | movement after step S103 was mentioned above, description is abbreviate | omitted.

According to the embodiment described above, the following effects can be obtained.
According to the projector 1 of the present embodiment, the length of the image data in the direction parallel to and perpendicular to the tilt direction is reduced in accordance with the correction amount as long as the correction amount S for correcting the trapezoidal distortion in tilt projection does not exceed the threshold L. When the correction amount S exceeds the threshold value L, the length of the image data in the direction parallel to the tilt direction is reduced to a predetermined length, and the length of the image data in the direction orthogonal to the tilt direction Second trapezoidal distortion correction is performed to reduce the height according to the correction amount S. That is, when the correction amount S of the trapezoidal distortion correction does not exceed the threshold L, the aspect ratio of the image data is maintained by the first trapezoidal distortion correction, and when the correction amount S exceeds the threshold L, the image is corrected by the second trapezoidal distortion correction. Although the aspect ratio of the data is not maintained, it is possible to suppress the loss of image data due to the trapezoidal distortion correction.

Further, when the correction amount S exceeds the threshold L, the notification is made when the trapezoidal distortion correction method is switched from the first trapezoidal distortion correction to the second trapezoidal distortion correction, so that the user is notified that the correction method is changed, and the first When it is desired to correct the keystone distortion, it is possible to prompt the user to review the installation position of the projector.

In addition, the user can set the correction amount S of the trapezoidal distortion correction by operating the trapezoidal distortion correction key 25g of the main body operating means 23 or the remote controller 25 to execute the first trapezoidal distortion correction or the second trapezoidal distortion correction. Become.

Further, it becomes possible to set the trapezoidal distortion correction amount S according to the installation angle of the projector 1 detected by the angle detection means 19 and execute the first trapezoidal distortion correction or the second trapezoidal distortion correction.

Further, since the threshold value L for switching from the first trapezoidal distortion correction to the second trapezoidal distortion correction can be changed, the threshold L is changed after confirming the corrected projected image, and the changed threshold L and the correction amount are changed. In accordance with S, it is possible to execute the trapezoidal distortion correction by switching the correction method.

When the trapezoidal distortion correction amount S exceeds the threshold value L, the length of the image data in the direction parallel to the tilt direction is reduced to a predetermined length instead of the second trapezoidal distortion correction, and is orthogonal to the tilt direction. A third trapezoidal distortion correction is executed to enlarge the length of the image data in the direction according to the correction amount S. This
When the correction amount S exceeds the threshold value L, pixel loss is eliminated thereafter, so that it is possible to prevent image quality deterioration of the projected image data.

Moreover, you may change the said embodiment as follows.
(Modification 1)
In the embodiment described above, the main body operating means 23 and the remote controller 25 are provided with the trapezoidal distortion correction key 25g for correcting the trapezoidal distortion in each direction, but the trapezoidal distortion correction key 25g instructs the start and end of the trapezoidal distortion correction. Keys may be used to perform keystone distortion correction in each direction by operating the cursor key 25d after operating the keystone distortion correction key 25g. That is, since only one operation key for keystone distortion correction is required, it becomes possible to perform keystone distortion correction without increasing the operation keys of the main body operating means 23 and the remote controller 25.

(Modification 2)
In the above-described embodiment, the trapezoidal distortion correction in the vertical tilt projection has been described.
It can also be applied to horizontal keystone distortion correction.

DESCRIPTION OF SYMBOLS 1 ... Projector, 6 ... Image input terminal, 10 ... Image projection means, 11 ... Light source, 12R,
12G, 12B ... Liquid crystal light valve, 13 ... Projection lens, 14 ... Liquid crystal drive means, 15 ... Trapezoid distortion correction means, 16 ... OSD processing means, 17 ... Image signal processing means, 18 ... Image signal input means, 19 ... Angle detection Means, 19a ... acceleration sensor, 20 ... control means, 21 ... storage means,
21a ... trapezoidal distortion correction information, 22 ... light source control means, 23 ... main body operation means, 24 ... operation signal receiving means, 25 ... remote controller, 30 ... power supply terminal, 31 ... power supply section, 40 ... notification means, SC ... screen, L: Threshold value, S: Correction amount.

Claims (7)

A light source, a light modulation device that modulates light emitted from the light source according to input image data, an image projection unit that projects image light modulated by the light modulation device as a projection image on a projection surface, A projector having
Based on a correction amount for correcting trapezoidal distortion that occurs when tilt projection is performed, the optical modulator includes a trapezoidal distortion correction unit that corrects the trapezoidal distortion by reducing or enlarging the image data,
The trapezoidal distortion correcting means is
The length of the image data in the direction orthogonal to the tilt direction is reduced according to the correction amount, and the length of the image data in the direction parallel to the tilt direction is reduced according to the correction amount. The first trapezoidal distortion correction;
A second method for reducing the length of the image data in a direction parallel to the tilt direction to a predetermined length and reducing the length of the image data in a direction orthogonal to the tilt direction toward the tilt direction according to the correction amount. With keystone distortion correction,
When the correction amount does not exceed a predetermined threshold, the first trapezoidal distortion correction is executed, and when the correction amount exceeds the predetermined threshold, the second trapezoidal distortion correction is executed. projector. The projector according to claim 1,
Further comprising a notification means,
The projector is configured to notify when the correction performed by the trapezoidal distortion correcting unit changes from the first trapezoidal distortion correction to the second trapezoidal distortion correction. The projector according to claim 1 or 2,
A projector further comprising input operation means for receiving an operation for setting the correction amount. The projector according to claim 3,
The trapezoidal distortion correction unit changes the threshold when a predetermined operation by the input operation unit is received, and the first trapezoidal distortion correction or the second trapezoid based on the threshold after the change and the correction amount. A projector that performs distortion correction. The projector according to any one of claims 1 to 4,
An angle detection means for detecting the installation angle of the projector;
The correction amount is set based on the detected installation angle. A projector according to any one of claims 1 to 5,
The trapezoidal distortion correction means reduces the length of the image data in a direction parallel to the tilt direction to a predetermined length, and sets the length of the image data in the direction orthogonal to the tilt direction according to the correction amount. With third trapezoidal distortion correction that expands toward the opposite direction,
The trapezoidal distortion correcting unit, when the correction amount exceeds the predetermined threshold, executes the third trapezoidal distortion correction instead of the second trapezoidal distortion correction. A light source, a light modulation device that modulates light emitted from the light source according to input image data, an image projection unit that projects image light modulated by the light modulation device as a projection image on a projection surface, A projector control method comprising:
A correction amount setting step for setting a correction amount for correcting trapezoidal distortion that occurs when tilt projection is performed;
The length of the image data in the direction orthogonal to the tilt direction is reduced according to the correction amount, and the length of the image data in the direction parallel to the tilt direction is reduced according to the correction amount. A first trapezoidal distortion correction step;
A second method for reducing the length of the image data in a direction parallel to the tilt direction to a predetermined length and reducing the length of the image data in a direction orthogonal to the tilt direction toward the tilt direction according to the correction amount. Trapezoidal distortion correction step;
If the correction amount does not exceed a predetermined threshold, the first trapezoidal distortion correction step is executed,
When the correction amount exceeds the predetermined threshold, a control step for executing the second trapezoidal distortion correction step;
A projector control method characterized by comprising:

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