JP3932987B2 - Image projection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image projection apparatus.
[0002]
[Prior art]
In a liquid crystal projector as an image projection apparatus, if the projection angle of an image from the liquid crystal projector with respect to a projection surface such as a screen is oblique, an image that should originally be rectangular is distorted into a trapezoid on the screen.
For this reason, a liquid crystal projector having a so-called auto keystone correction function for correcting a trapezoidal distortion of an image on a screen by distorting an image on the liquid crystal panel in reverse is known. For example, a sensor for detecting tilt is built in the liquid crystal projector, and trapezoidal distortion corresponding to the tilt of the liquid crystal projector detected by the sensor is automatically generated in the image on the liquid crystal panel.
[0003]
[Problems to be solved by the invention]
By the way, when the keystone correction as described above is performed, the trapezoidal distortion of the image on the screen is corrected, but the image quality deteriorates in a fixed pixel device such as a liquid crystal panel. In particular, when the keystone correction is performed when the degree of the keystone distortion of the image on the screen is small, the image quality is significantly deteriorated as compared with the case where the keystone correction is not performed. Therefore, in such a case, it is preferable to prevent deterioration in image quality even at the expense of the shape of the image on the screen.
On the other hand, the screen is not always installed correctly in the vertical direction. For this reason, when the auto keystone correction functions, the image on the screen obtained by the auto keystone correction is not always corrected correctly.
[0004]
The present invention has been made in view of the above-described conventional problems. An object of the present invention is to improve an image generated by an automatic keystone correction function in an image projection apparatus having an automatic keystone correction function. It is to provide a projection device.
[0005]
[Means for Solving the Problems]
The image projection apparatus according to the present invention projects an image displayed on the image display unit onto a projection surface arranged along a substantially vertical plane using light, and according to a projection angle of the image with respect to the projection plane. An image projection apparatus capable of correcting the trapezoidal distortion of the image projected on the projection plane, and an inclination detection means for detecting an inclination of the projection direction of the image with respect to the horizontal plane, and a trapezoid corresponding to the set correction value Image conversion means for generating distortion in the image displayed on the image display means; and when the inclination detected by the inclination detection means is within a specific range near zero, trapezoid distortion is applied to the image displayed on the image display means. A first correction value that is not generated is specified, and when the tilt is out of a specific range, a second correction value that generates trapezoidal distortion is specified according to the tilt, and the specified first or second correction value is the image. Set as conversion method A correction value specifying unit that an input means for inputting an adjustment value, each time the said adjustment value is changed, the adjustment value of the changed, the image converting means has been set to the first or second correction Adjusting means for adding to the value and changing the first or second correction value set in the image conversion means with a new correction value generated by the addition .
[0007]
In the present invention, when the inclination of the projection direction of the image with respect to the horizontal plane detected by the inclination detecting means is an inclination of a specific range, the correction value specifying means specifies a correction value that does not cause trapezoidal distortion in the image. The trapezoidal distortion correction of the image displayed on the display means is not performed.
In the present invention, the adjustment value input by the input unit is added to the correction value specified according to the inclination of the projection direction of the image with respect to the horizontal plane detected by the inclination detection unit, and the correction value becomes a new correction value. The correction value given to the specifying means and specified by the correction value specifying means is finely adjusted by the adjustment value input by the input means.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a schematic configuration of a liquid crystal projector as an image projection apparatus to which the present invention is applied.
A liquid crystal projector 1 shown in FIG. 1 includes a light source 2, an integrator optical system 5, reflection mirrors 4, 9, 11, and 12, a condensing lens 10, dichroic mirrors 6 and 7, liquid crystal panels 20R, 20G, and 20B, a polarizing plate 21R, 21G, 21B, 22R, 22G, 22B, dichroic prism 30, projection optical system 25, and the like.
[0009]
The light source 2 is composed of a discharge lamp 2 a and a reflective condenser mirror 2 b, and the light emitted from the discharge lamp 2 a is condensed by the reflective condenser mirror 2 b and emitted to the reflective mirror 4.
[0010]
The reflection mirror 4 reflects the illumination light L from the light source 2 toward the integrator optical system 5.
The integrator optical system 5 converts the illumination light L from the light source 2 as a whole into illumination light with a uniform polarization direction including a large amount of S-polarized light components, and outputs the illumination light.
The condenser lens 10 condenses the illumination light L that has passed through the integrator optical system 5 so as to be superimposed on the liquid crystal panels 22R, 22G, and 22B.
[0011]
The dichroic mirror 6 is inclined 45 degrees with respect to the optical axis of the illumination light L that has passed through the integrator optical system 5, and only the light LR in the red wavelength region of the illumination light L is reflected toward the reflection mirror 12. Transmits light LGB in other wavelength regions.
[0012]
The reflection mirror 11 is inclined 45 degrees with respect to the optical axis of the light LR reflected by the dichroic mirror 6, and reflects the light LR toward the liquid crystal panel 20R.
[0013]
The dichroic mirror 7 is inclined 45 degrees with respect to the optical axis of the light LGB transmitted through the dichroic mirror 6, and only the light LG in the green wavelength region of the light LGB is directed toward the liquid crystal panel 20G. It is inclined 45 degrees with respect to the optical axis of the illumination light L that has passed, and only the light LG in the green wavelength region of the illumination light L is reflected toward the liquid crystal panel 20G, and the light LB in other wavelength regions is transmitted. .
[0014]
The reflection mirrors 9 and 11 reflect the light LB in the blue wavelength range toward the liquid crystal panel 20B.
[0015]
The liquid crystal panels 20R, 20G, and 20B are respectively disposed at predetermined positions with respect to the three side surfaces of the cubic dichroic prism 30.
Polarizing plates 21R, 21G, and 21B as polarizers and polarizing plates 22R, 22G, and 22B as analyzers are arranged in parallel on the incident and exit sides of the liquid crystal panels 20R, 20G, and 20B, respectively.
[0016]
The liquid crystal panels 20R, 20G, and 20B are entirely incident on the respective light beams LR, LG, and LB, and are applied to the liquid crystal panels 20R, 20G, and 20B according to video signals corresponding to the three primary colors red, green, and blue. Modulates the intensity of LR, LG and LB. The color lights LR, LG, and LB having a predetermined polarization direction transmitted through the polarizing plates 21R, 21G, and 21B are subjected to rotation of the polarization plane that rotates the polarization plane based on the video signals applied to the liquid crystal panels 20R, 20G, and 20B. The predetermined polarization component of the transmitted light is transmitted through the polarizing plates 22R, 22G, and 22B and is incident on the dichroic prism 30.
[0017]
The dichroic prism 25 is configured by, for example, bonding a plurality of glass prisms, and interference filters 30a and 30b having predetermined optical characteristics are formed on the bonding surfaces of the glass prisms.
The interference filter 30a reflects the blue light LB and transmits the red light LR and the green light LG. The interference filter 30b reflects the red light LR and transmits the green light LG and the blue light LB.
Accordingly, the color lights LR, LG, LB modulated by the liquid crystal panels 20R, 20G, 20B are combined and enter the projection optical system 28.
[0018]
For example, the projection optical system 25 projects the image light incident from the dichroic prism 30 onto the screen Sc. A color image is displayed on the screen Sc.
[0019]
FIG. 2 is a configuration diagram of a signal processing system of the liquid crystal projector 1 according to an embodiment of the present invention.
The signal processing system of the liquid crystal projector 1 includes a signal processing circuit 40, a frame memory 41 , a scaler 42, a 3D γ circuit 43, a panel drive circuit 44, a processor 50, a ROM (Read Only Memory) 55, and an input unit. 51 and an inclination detection sensor 52. The scaler 42 is an embodiment of the image conversion means of the present invention, the inclination detection sensor 52 is an embodiment of the inclination detection means of the present invention, and the input unit 51 is an embodiment of the input means of the present invention. is there. The processor 50, the ROM 55, and the software and data stored in the ROM 55 constitute the correction value specifying means and adjusting means of the present invention.
[0020]
The signal processing circuit 40 performs predetermined processing on the video signal input from the video signal input unit 40a and the graphic signal input from the graphic signal input unit 40b, and converts them into R, B, and G color signals. Are output to the frame memory 41 as image data.
[0021]
The frame memory 41 receives image data for each frame from the signal processing circuit 40 and stores it.
[0022]
The scaler 42 performs trapezoidal distortion correction on the image data stored in the frame memory 41 based on the correction value M from the processor 50, and outputs the result to the 3Dγ circuit 43.
Here, a trapezoidal distortion correction method in the scaler 42 will be described with reference to FIG.
FIG. 3A shows image data for one frame, and FIG. 3B shows image data for one line.
When attention is paid to the line L along the upper side of the trapezoid in the frame, the image data of the line L0 corresponding to the line L is read from the frame memory 41 storing the original image data to the scaler 42. Image data compressed by performing interpolation processing while ensuring the read pixel linearity is generated. That is, the number of pixels is reduced while making the image look the same. A new line L is generated by displaying black on the left and right areas of the image data generated by this compression.
[0023]
A trapezoidal image is generated by performing such pixel number conversion processing for each line on all the lines while gradually changing the compression rate.
The compression rate in this pixel number conversion process is determined by the correction value M given from the processor 50 to the scaler 42.
[0024]
The 3D γ circuit 43 adjusts the gain of the image data that has been corrected for trapezoidal distortion in the scaler 42, and outputs this to the panel drive circuit 44.
The panel drive circuit 44 converts the image data input from the 3D γ circuit 43 into drive signals for driving the liquid crystal panels 20R, 20G, and 20B, and outputs the drive signals to the liquid crystal panels 20R, 20G, and 20B.
[0025]
The processor 50 is connected to the ROM 55 via the bus B. In addition, an input unit 51 and an inclination detection sensor 52 are connected to the processor 50. The processor 50 controls various operations and various circuits in accordance with software stored in the ROM 55. The processor 50 specifies the correction value M to be given to the scaler 42 according to the signal 52 s detected by the inclination detection sensor 52.
[0026]
The input unit 51 is a human interface for inputting various data to the liquid crystal projector 1 from the outside. The input unit 51 is used, for example, to input a signal 51 s for selecting a desired adjustment from various image adjustments performed in the liquid crystal projector 1. Further, the signal 51s includes a correction value given to the scaler 42 in the manual mode described later and an adjustment value in the provisional manual mode.
[0027]
The tilt detection sensor 52 is built in the liquid crystal projector 1 and detects the tilt of the projection direction of the image with respect to the horizontal plane of the liquid crystal projector 1.
Specifically, as shown in FIG. 4A, assuming that the projection direction is the lower end Le of the image light L projected from the liquid crystal projector 1, when the liquid crystal projector 1 is placed on the horizontal plane HP, the vertical direction The image light L is projected perpendicularly to the screen SC placed at, and the inclination is zero. On the other hand, as shown in FIG. 4B , when the liquid crystal projector 1 is tilted by the adjuster ad protruding from the bottom surface of the liquid crystal projector 1, the tilt detection is performed when the tilt of the lower end Le of the image light L with respect to the horizontal plane HP is θ. The sensor 52 detects this inclination θ. As the tilt detection sensor 52, for example, an acceleration sensor or the like is used.
[0028]
Next, a method for specifying the correction value M given to the scaler 42 will be described.
FIG. 5 is a diagram showing an image on the screen Sc and an image on the liquid crystal panel 20 after the keystone correction. (A) shows a case where the inclination θ is relatively large, and (b) shows a case where the inclination θ is small. Note that the case where the inclination θ is small is, for example, within about ± 2 °.
As shown in FIG. 5, when the image IM on the liquid crystal panel 20 is corrected to a trapezoidal shape, a rectangularly corrected image IMs and a trapezoidal light region are formed on the outer periphery of the image IMs. .
Incidentally, as can be seen from FIG. 5, when the inclination θ is relatively large, the number of pixels of the image IM on the liquid crystal panel 20 is reduced in the entire left and right regions in the vertical direction, but when the inclination θ is small, the image IM is vertical. The number of pixels is reduced on the left and right sides in the direction, but the number of pixels is not reduced in the lower part. For this reason, when the inclination θ is small, when the trapezoidal correction is performed, the image quality on the upper side in the vertical direction of the screen IMs on the screen Sc is significantly lowered as compared with the lower side.
[0029]
FIG. 6 is a graph showing an example of the relationship between the correction value M given to the scaler 42 from the processor 50 and the inclination θ in the present embodiment.
As shown in FIG. 6, in the present embodiment, the correction value M is zero in a specific range R in which the slope θ is near zero, and the correction value M increases or decreases according to the slope θ in other regions. To do.
The specific range R is, for example, a range of −2 ° to 2 °.
When the slope θ is in a specific range R, the scaler 42 is always given a zero correction value M, and thus the keystone distortion correction is not performed in the scaler 42.
[0030]
The relationship between the correction value M and the inclination θ is stored as a table in the ROM 55, for example. When the processor 50 detects the inclination θ from the inclination detection sensor 52, the processor 50 reads the correction value M corresponding to the inclination θ and gives this to the scaler 42.
Thereby, trapezoidal distortion correction is automatically performed.
[0031]
Next, an example of a processing procedure for correcting the trapezoidal distortion of the liquid crystal projector 1 having the above configuration will be described.
First, the processor 50 determines whether the input state of the input unit 51 is set to the auto mode or the manual mode (step S1).
Here, the auto mode is a mode in which the correction value M corresponding to the inclination θ is automatically specified from the inclination θ detected by the inclination detection sensor 52 and applied to the scaler 42. The manual mode is a mode in which the user arbitrarily corrects the trapezoidal distortion by inputting the correction value M from the input unit 51.
[0032]
In the auto mode, the processor 50 acquires the inclination θ from the inclination detection sensor 52 (step S2), specifies the correction value M from the inclination θ (step S3), and sets the correction value M in the scaler 42. (Step S4).
[0033]
Next, the processor 50 determines whether it is the auto mode or the provisional manual mode (step S5).
The provisional manual mode is a mode in which the correction value M obtained in the auto mode can be adjusted by the adjustment value K from the input unit 51. In other words, when trapezoidal distortion correction is performed with the correction value M obtained in the auto mode, this correction value M is adjusted to enable fine adjustment of the image.
[0034]
In the provisional manual mode, the processor 50 acquires the current correction value M specified in the auto mode (step S6).
Next, the processor 50 acquires the adjustment value K input from the input unit 51 (step S7).
[0035]
The processor 50 adds the adjustment value K to the current correction value M to obtain a new correction value (step S8), and sets this in the scaler 42 (step S9).
As a result, fine adjustment of the image corrected for trapezoidal distortion in the auto mode is performed.
[0036]
Next, it is determined whether or not the provisional manual mode has been completed (step S10). If the provisional manual mode has been completed, the process returns to step S1 again.
[0037]
As described above, according to the present embodiment, when the trapezoidal distortion correction is performed in the auto mode, if the inclination θ is small and the trapezoidal distortion of the image on the screen Sc is small enough not to be conscious, it is positively performed. Does not perform keystone correction. As a result, it is possible to prevent the deterioration of the image quality on the screen that occurs when the trapezoidal distortion correction is performed at such a small inclination θ.
Further, according to the present embodiment, the provisional manual mode for adjusting the correction value M obtained in the auto mode that automatically performs the trapezoidal distortion correction is provided, thereby greatly simplifying the image adjustment work. Can do. For example, when the trapezoidal distortion correction is performed in the manual mode, the correction value M must be set from scratch, which takes time and effort. However, when adjusting the correction value M obtained in the auto mode, Quick adjustment is possible.
In addition, according to the present embodiment, when the tilt θ is small in the auto mode and the trapezoidal distortion correction is not automatically performed, if it is desired to correct the trapezoidal distortion, the adjustment can be quickly performed by using the provisional manual mode. Adjustment is possible.
[0038]
In addition, this invention is not limited to embodiment mentioned above. In the above-described embodiment, the correction value M is specified by preparing a table of the inclination θ and the correction value M in the ROM 55 in advance. However, the correction value M can also be specified by calculation using a predetermined calculation formula.
[0039]
【The invention's effect】
According to the present invention, it is possible to prevent deterioration in image quality due to unnecessary keystone correction.
Further, according to the present invention, fine adjustment of an image by auto keystone correction can be easily performed.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of a liquid crystal projector as an image projection apparatus to which the present invention is applied.
FIG. 2 is a configuration diagram of a signal processing system of the liquid crystal projector 1 according to an embodiment of the present invention.
FIG. 3 is a diagram for explaining a trapezoidal distortion correction method in the scaler 42;
4 is a diagram for explaining an inclination θ of the liquid crystal projector 1. FIG.
FIG. 5 is a diagram illustrating an image on the screen SC and an image on the liquid crystal panel 20 after trapezoid correction.
FIG. 6 is a graph showing an example of a relationship between a slope θ and a correction value M.
FIG. 7 is a flowchart for explaining an example of a trapezoidal distortion correction processing procedure of the liquid crystal projector.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Liquid crystal projector, 2 ... Light source, 4 ... Reflection mirror, 5 ... Integrator optical system, 6, 7 ... Dichroic mirror, 20R, 20G, 20B ... Liquid crystal panel, 30 ... Dichroic prism, 25 ... Projection optical system, 40 ... Signal Processing circuit 41 ... Frame memory 42 ... Scaler 43 ... 3Dγ circuit 44 ... Panel drive circuit 50 ... Processor 51 ... Input section 52 ... Tilt detection sensor 55 ... ROM Sc ... Screen

Claims (1)

The image displayed on the image display means is projected onto a projection plane arranged along a substantially vertical plane using light, and is projected on the projection plane generated according to the projection angle of the image with respect to the projection plane. An image projection device capable of correcting trapezoidal distortion of an image,
Inclination detecting means for detecting the inclination of the projection direction of the image with respect to the horizontal plane;
Image conversion means for generating a trapezoidal distortion corresponding to the set correction value in the image displayed on the image display means;
A first correction value that does not cause trapezoidal distortion in the image displayed on the image display means is specified when the inclination detected by the inclination detection means is within a specific range near zero, and when the inclination is outside the specific range. Correction value specifying means for specifying a second correction value for generating a trapezoidal distortion according to the inclination, and setting the specified first or second correction value in the image conversion means ;
An input means for inputting an adjustment value;
Each time the adjustment value is changed, the changed adjustment value is added to the first or second correction value set in the image conversion means, and a new correction value generated by the addition is added. And adjusting means for changing the first or second correction value set in the image converting means,
An image projection apparatus.

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