JP3302942B2 - LCD projector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector capable of correcting trapezoidal distortion of a display screen generated when an image is projected on a screen.

[0002]

2. Description of the Related Art FIG. 4 is a diagram for explaining the cause of trapezoidal distortion. The liquid crystal projector 1 is a projector that enlarges and projects a video signal supplied from a video signal source (not shown) such as a computer on a screen 2. As shown in FIG. 4, when the liquid crystal projector 1 is arranged to be inclined with respect to the screen 2, the distance between the liquid crystal projector 1 and the screen 2 is not constant above and below the display screen 3. The display screen 3 has a trapezoidal shape with different horizontal lengths. This is called trapezoidal distortion.

In the conventional liquid crystal projector 1, the following image correction is performed to avoid the trapezoidal distortion as described above. That is, the liquid crystal projector 1 is a projector using the liquid crystal panel 6 (see FIG. 1), and changes a voltage applied to the liquid crystal panel 6 according to a video signal supplied from a video signal source to set a video on the liquid crystal panel 6. Then, by irradiating the LCD panel 6 with the image set with light,
The image is projected by passing and blocking the light with the liquid crystal panel 6.

Here, when trapezoidal distortion of the display screen 3 occurs, the user operates a remote controller or the like to
Adjustment is made so that trapezoidal distortion of the display screen 3 of the screen 2 is eliminated. In the liquid crystal projector 1, upon receiving such a user's instruction to correct the trapezoidal distortion, the trapezoidal distortion correction circuit 7 (see FIG. 1), as shown in FIG. The video signal is corrected to correction data so that the horizontal length is inverted upside down (trapezoidal video), and a trapezoidal video according to the correction data is set on the liquid crystal panel 6.

The liquid crystal projector 1 can display a square or rectangular screen on the screen 2 by backlighting a trapezoidal image set on the liquid crystal panel 6 with the lamp 4 (see FIG. 1).

[0006]

However, in the conventional liquid crystal projector 1, as shown in FIG. 5, a portion other than the trapezoidal image set on the liquid crystal panel 6 (a triangular portion at both left and right ends of the liquid crystal panel 6). ) Is set to black, but the liquid crystal panel 6 cannot completely block light even in a region set to black. Therefore, even when the trapezoidal distortion is corrected as described above, as shown in FIG.
The portion where the trapezoidal distortion occurs (the region set to black) is displayed slightly brighter. In particular, when the display is performed in a completely dark room or the like, this slightly bright portion becomes very conspicuous, giving a sense of discomfort to the viewer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and it is possible to prevent the occurrence of slightly bright portions on both sides of a display screen after correcting a trapezoidal distortion of the display screen. The purpose is to obtain a liquid crystal projector that can be used.

[0008]

According to a first aspect of the present invention, there is provided a liquid crystal projector, comprising: an irradiating means for irradiating light; and a light irradiating from the irradiating means in accordance with an image set by changing a voltage. A liquid crystal panel that passes or blocks and projects an image, and a pair of light shielding plates that are disposed on the front side of the liquid crystal panel and on both sides of the liquid crystal panel and block light emitted from the irradiation unit to the liquid crystal panel, By converting the video signal into correction data according to the amount of operation from the user and outputting the correction data to the liquid crystal panel, the voltage applied to the liquid crystal panel is changed to set a trapezoidal image, and a pair of light shielding plates So that the position of the inner side of is the same as the position of the hypotenuse of the trapezoidal image set on the LCD panel,
Trapezoidal distortion correction means for rotating a pair of light shielding plates.

According to a second aspect of the invention, there is provided a liquid crystal projector in which a pair of light shielding plates are rotatable in both directions.

According to a third aspect of the invention, there is provided a liquid crystal projector in which a pair of light shielding plates are disposed on both sides of the liquid crystal panel.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. FIG. 1 is a schematic configuration diagram showing a liquid crystal projector according to an embodiment of the present invention. In the figure, a liquid crystal projector 1A is a projector that enlarges and projects a video signal supplied from a video signal source (not shown) such as a computer on a screen 2 as described above. In FIG. 1, it is assumed that the liquid crystal projector 1 </ b> A is arranged to be inclined with respect to the screen 2, and a display screen 3 displayed on the screen 2 has a trapezoidal distortion.

In the liquid crystal projector 1A, a lamp (irradiating means) 4 irradiates light, and a lens (irradiating means) 5 condenses the light radiated from the lamp 4 and irradiates the liquid crystal panel 6 ( Backlight). The liquid crystal panel 6 sets an image by changing a voltage in accordance with the correction data D output from the trapezoidal distortion correction circuit 7, and projects an image by passing or blocking light according to the set image. Note that this liquid crystal panel 6
(Red), G (Green), and B (Blue).

Trapezoidal distortion correction circuit (trapezoidal distortion correction means) 7
Converts a video signal supplied from a video signal source into correction data D and outputs the correction data D to the liquid crystal panel 6 in accordance with a correction amount M which is a user's operation amount of a remote controller (not shown) or the like. Thus, the voltage applied to the liquid crystal panel 6 is changed to set a trapezoidal image as shown in FIG. Further, the trapezoidal distortion correction circuit 7 sets the positions of the inner sides of the pair of light shielding plates 8 to be the same as the positions of the oblique sides of the trapezoidal image set on the liquid crystal panel 6 according to the correction amount M (that is, the trapezoidal distortion correction circuit 7). An actuator (not shown) is operated so that a triangular black region set at both left and right ends of the liquid crystal panel 6 is completely covered with the pair of light shielding plates 8).

A pair of light-shielding plates 8 block light emitted from the lamp 4 to the liquid crystal panel 6 through the lens 5, and are disposed on the front side of the liquid crystal panel 6 (on the side irradiated with light from the lamp 4). It is arranged on both sides of the liquid crystal panel 6. As described above, the pair of light shielding plates 8 are configured to be rotatable so as to cover a black region set in the liquid crystal panel 6 under the control of the trapezoidal distortion correction circuit 7. FIG.
Here, the positions of the pair of light shielding plates 8 and the position of the display screen 3 of the screen 2 are shown upside down and left and right for easy viewing.

Next, the operation will be described. First, an operation of displaying an image on the screen 2 by the liquid crystal projector 1A will be described. When receiving the video signal from the video signal source, the liquid crystal projector 1A sends the video signal to the trapezoidal distortion correction circuit 7. The trapezoidal distortion correction circuit 7 converts the video signal into correction data D,
Is set on the LCD panel 6 according to. At this time, the liquid crystal panel 7 displays R (red), G (green) and B (blue).
And a trapezoidal distortion correction circuit 7
Is a voltage applied to the liquid crystal panel 6 so that all the three panels transmit light when the liquid crystal panel 6 is set to white and all the three panels are blocked when the liquid crystal panel 6 is set to black. To change.

With the image set on the liquid crystal panel 6,
When the light emitted from the lamp 4 is applied to the liquid crystal panel 6 via the lens 5 (backlight), the light is
The video is projected and projected on the screen 2. On the screen 2, an image is displayed as a display screen 3.

Next, the operation for correcting the trapezoidal distortion of the display screen 3 will be described. When the user recognizes that the trapezoidal distortion of the display screen 3 has occurred when the video is displayed on the screen 2 as described above, the user operates a remote controller or the like to adjust so as to correct the trapezoidal distortion. . The instruction to correct the trapezoidal distortion is sent to the trapezoidal distortion correction circuit 7 as a correction amount M.

According to the correction amount M, the trapezoidal distortion correction circuit 7 generates a trapezoidal image reverse to the trapezoidal distortion (that is, a trapezoidal image whose horizontal length is upside down) as shown in FIG. Thus, the video signal is converted into correction data D, and an image corresponding to the correction data D is set on the liquid crystal panel 6. At this time, as shown in FIG. 5, portions other than the trapezoidal image (triangular portions at both left and right ends of the liquid crystal panel 6) are set to black.

The trapezoidal distortion correction circuit 7 includes a liquid crystal panel 6
Is set to a trapezoidal image, and according to the correction amount M,
By controlling an actuator (not shown), as shown in FIG. 2, the positions of the inner sides of the pair of light shielding plates 8 are the same as the positions of the oblique sides of the trapezoidal image set on the liquid crystal panel 6. Rotate as follows.

In a state where an image is set on the liquid crystal panel 6 and the pair of light shielding plates 8 are rotated to positions covering the black area, light emitted from the lamp 4 passes through the lens 5 to the liquid crystal panel 6. When the backlight 6 is illuminated (backlit), light is transmitted and blocked in a trapezoidal image portion set on the liquid crystal panel 6, and the pair of light shielding plates 8 completely block light.

When the light is completely blocked by the pair of light shielding plates 8, the light does not reach the black region of the liquid crystal panel 6, and as a result, the display screen 3 displayed on the screen 2 is displayed.
As shown in FIG. 3, slightly bright portions do not occur on both sides of the display screen 3 and the outline of the display screen 3 is clearly displayed.

As described above, according to this embodiment,
Since a portion other than the trapezoidal image set on the liquid crystal panel 6 is configured to be covered by the pair of light shielding plates 8, light is not irradiated to the black region of the liquid crystal panel 6, It is possible to prevent a bright portion from being generated.

In the above-described embodiment, a case has been described in which trapezoidal distortion having a long upper side and a short lower side is corrected. However, the present invention is not limited to this, and trapezoidal distortion having a shorter upper side and a longer lower side can be corrected. be able to. in this case,
This can be realized by configuring the pair of light shielding plates 8 to be rotatable in both directions.

Further, not only trapezoidal distortion in which the lengths of the upper and lower sides of the display screen 3 are different, but also trapezoidal distortion in which the lengths of the left and right sides are different can be corrected. In this case, it can be realized by disposing the pair of light shielding plates 8 not only on both left and right sides of the liquid crystal panel 6 but also on both upper and lower sides.

[0025]

As described above, according to the first aspect of the present invention, the irradiating means for irradiating light and the light irradiating from the irradiating means are passed according to the image set by changing the voltage. A liquid crystal panel for projecting an image by blocking the liquid crystal panel, a pair of light shielding plates disposed on the front side of the liquid crystal panel and on both sides of the liquid crystal panel, and blocking light emitted from the irradiating means to the liquid crystal panel; By converting the video signal to correction data according to the operation amount from the, and outputting the correction data to the liquid crystal panel, the voltage applied to the liquid crystal panel is changed to set a trapezoidal image, and a pair of light shielding plates A trapezoidal distortion correcting means for rotating a pair of light shielding plates so that the position of the inner side is the same as the position of the oblique side of the trapezoidal image set on the liquid crystal panel, Trapezoid The light irradiated to the portion other than the video can be completely shut off, an effect that little bright portion on both sides of the screen display of the can be prevented from occurring.

According to the second aspect of the present invention, since the pair of light shielding plates are configured to be rotatable in both directions, there is an effect that upside down trapezoidal distortion can be corrected.

According to the third aspect of the present invention, the pair of light-shielding plates are disposed on the left and right sides and the upper and lower sides of the liquid crystal panel. There is an effect that trapezoidal distortion having different side lengths can be corrected.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a liquid crystal projector according to an embodiment of the present invention.

FIG. 2 is a view showing a rotation position of a pair of light shielding plates.

FIG. 3 is a diagram showing a display screen displayed by the liquid crystal projector according to the embodiment of the present invention.

FIG. 4 is a diagram for explaining a cause of trapezoidal distortion.

FIG. 5 is a diagram illustrating an image corrected to a trapezoid set on a liquid crystal panel.

FIG. 6 is a diagram showing a display screen displayed by a conventional liquid crystal projector.

[Explanation of symbols]

 Reference Signs List 1A liquid crystal projector 2 screen 4 lamp (irradiation means) 5 lens (irradiation means) 6 liquid crystal panel 7 trapezoidal distortion correction circuit (trapezoidal distortion correction means) 8 light shielding plate

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03B 21/132 H04N 5/74

Claims (3)

(57) [Claims] An irradiating means for irradiating light; a liquid crystal panel for projecting an image by passing or blocking light emitted from said irradiating means in accordance with an image set by changing a voltage; A pair of light-shielding plates disposed on the front side of the panel and on both sides of the liquid crystal panel to block light emitted from the irradiating means to the liquid crystal panel; and correcting a video signal according to a user's operation amount. By converting the correction data into data and outputting the correction data to the liquid crystal panel, the voltage applied to the liquid crystal panel is changed to set a trapezoidal image, and the position of the inner side of the pair of light shielding plates is set to the liquid crystal panel. A trapezoidal distortion correcting means for rotating the pair of light shielding plates so as to be at the same position as the position of the oblique side of the trapezoidal image set in the liquid crystal projector. 2. The liquid crystal projector according to claim 1, wherein the pair of light shielding plates are rotatable in both directions. 3. The liquid crystal projector according to claim 1, wherein a pair of light shielding plates are arranged on both sides of the liquid crystal panel.