JP3831438B2 - Liquid crystal display - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal display device that displays an image by projecting it onto a screen (hereinafter also referred to as “screen”), and more particularly to a liquid crystal display device that can correct distortion of the projected image.
[0002]
[Prior art]
In a liquid crystal display device (hereinafter also referred to as a “projector”) 14 that displays an image by projecting onto the screen 15, as shown in FIG. Since the projection angle with respect to the screen 15 does not become a right angle, the projection image 16 produces a distortion called a trapezoidal distortion in which the length in the horizontal direction is different above and below. Therefore, as shown in Japanese Patent Application No. 3-92207, the trapezoidal distortion is corrected by correcting the image displayed on the liquid crystal panel into a trapezoid that is upside down with the image projected on the screen 15. It has been resolved. Specifically, if the number of pixels of the liquid crystal panel is 480 horizontal pixels and 240 vertical lines, the effective display period of the video signal is displayed with 480 pixels as shown in FIG. 5A when correction is not performed. When the correction is performed, the effective display period of the video is compressed as shown in FIG. 5B (when m is the correction amount, the short side of the trapezoid becomes (480-2m) pixels. ) Display and blanking is added to the pixels before and after that by the circuit shown in FIG. This circuit switches the switch 17 based on the blanking pulse, and selectively supplies a video signal or a black level signal to the liquid crystal panel. Further, the switching is specifically performed at the timing shown in FIG. That is, when the blanking pulse shown in FIG. 7B is high (H) (effective display period), a video signal is supplied to the liquid crystal panel, and when it is low (L), a black level signal is supplied to the liquid crystal panel.
[0003]
[Problems to be solved by the invention]
When an image for correcting trapezoidal distortion is displayed on a liquid crystal panel having an arrangement shifted by 0.5 pixels for each horizontal scanning line (hereinafter also referred to as “delta arrangement”) according to the above-described conventional technique, the upper direction of the figure is the liquid crystal When it corresponds to the downward direction of the panel, it becomes as shown in FIG. Here, the image displayed on the liquid crystal panel causes a deviation A of 1.5 pixels from the image of the immediately above horizontal scanning line alternately on the left and right in the horizontal scanning line in which the correction amount is increased by one pixel, and between the other horizontal scanning lines. It is larger than the image shift (0.5 pixels). Therefore, there is a problem that the boundary between the image and blanking is uneven as a whole.
[0004]
The present invention has been made to solve the above-described problems, and an object of the present invention is to display a boundary between the image and blanking when displaying an image for correcting trapezoidal distortion on a liquid crystal panel having a delta arrangement. Is to make it smooth as a whole.
[0005]
[Means for Solving the Problems]
A liquid crystal display device according to the present invention is a liquid crystal display device that displays an image by projecting to an external screen, and includes a liquid crystal display means, a correction amount determination means, a blanking creation means, a video signal creation means, And compression display means. Here, the liquid crystal display means has a liquid crystal panel having an arrangement shifted by 0.5 pixels for each horizontal scanning line, and displays an image on the liquid crystal panel. The correction amount determining means determines the correction amount based on an external operation when the image projected on the screen from the liquid crystal panel has a trapezoidal distortion. Further, the blanking generation means, based on the correction amount determined by the correction amount determination means, to create a blanking pulse for displaying the blanking for each horizontal scan line. The video signal creating means adds the blanking pulse created by the blanking creating means to the video signal and supplies it to the liquid crystal display means. The compression display means generates a drive signal for compressing and displaying the video on the liquid crystal panel based on the correction amount determined by the correction amount determination means, and supplies the drive signal to the liquid crystal display means. Further, the blanking creation means includes a correction amount change line determination means and a blanking pulse generation means. The correction amount change line determination unit determines a horizontal scanning line for changing the correction amount based on the correction amount determined by the correction amount determination unit. The blanking pulse generating means creates a blanking pulse in which the pulse width is changed by one pixel on the horizontal scanning line determined by the correction amount changing line determining means.
[0006]
Preferably, the blanking creating means further comprises a line determination means is determined by the correction amount change line determination unit horizontal scan line to determine whether the even line or an odd line. The blanking pulse generating means narrows the pulse width by one pixel after the effective display period in the case of an odd line, and 1 before the effective display period in the case of an even line , based on the result determined by the line determination means. Narrow the pulse width for pixels.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.
[0008]
FIG. 1 is a block diagram showing the overall configuration of a liquid crystal display device according to an embodiment of the present invention. As shown in FIG. 1, the liquid crystal display device includes a liquid crystal panel 13 having an arrangement shifted by 0.5 pixels for each horizontal scanning line, and a sample and hold circuit 11 for holding a video signal supplied to the liquid crystal panel 13 for a certain period. The horizontal shift register 10 that starts the display of the video signal on the liquid crystal panel 13 by the input start pulse and performs the horizontal driving in the video display based on the input drive signal, and the horizontal scan for displaying the video And a vertical shift register 12 for driving the lines in the vertical direction. In addition, the liquid crystal display device includes a line counter 1 that counts the horizontal synchronization signal H while being reset by the vertical synchronization signal V, a correction amount instruction unit 3 that determines a correction amount by an external operation, and a correction amount instruction unit 3. The correction amount change line determination unit 2 that determines a horizontal scanning line (hereinafter also referred to as “correction amount change line”) that changes the correction amount based on the correction amount data signal supplied from the correction amount change line determination unit 2. Based on the signals input from the odd / even line discriminating circuit 7 and the odd / even line discriminating circuit 7 for discriminating whether the horizontal scanning line determined to change the correction amount is an odd line or an even line. A blanking pulse generation circuit 8 for generating a blanking pulse for displaying blanking, and adding the blanking pulse to the video signal to Including blanking circuit 9 supplies to the pull-and-hold circuit 11. Further, this liquid crystal display device is supplied from a pixel number counter 5 that outputs a horizontal position signal indicating a driving position in the horizontal direction by counting the clock signal CLK while being reset by the horizontal synchronization signal H, and the correction amount instruction unit 3. The horizontal position supplied from the pixel number counter 5 by determining whether to increase or decrease the correction amount for each correction amount change line based on the correction amount data signal and the signal supplied from the correction amount change line determination unit 2 A horizontal compression rate determination unit 4 that generates a mask pulse based on the signal, and a clock mask circuit 6 that supplies a drive signal to the horizontal shift register 10 after thinning out the clock signal CLK by the mask pulse.
[0009]
Next, the operation of the liquid crystal display device according to the embodiment of the present invention will be described. First, the projector 14 in FIG. 4 operates the correction amount from the outside so that the image projected on the screen 15 has no trapezoidal distortion. Then, the correction amount is determined by the correction amount instructing unit 3 in FIG. 1 by this operation. The correction amount instruction unit 3 supplies a correction amount data signal corresponding to the determined correction amount to the correction amount change line determination unit 2, and the correction amount change line determination unit 2 receives the correction amount data signal and the drive line from the line counter 1. The horizontal scanning line determines which correction amount is to be changed. Further, the odd / even line discriminating circuit 7 discriminates whether the correction amount change line determined by the correction amount change line determination unit 2 is an odd line or an even line, and a discrimination signal for each correction amount change line. Is output. Here, the blanking pulse generation circuit 8 generates a blanking pulse shown in FIG. 2B based on the clock signal CLK. This blanking pulse becomes high (H) during the effective display period of each horizontal scanning line, and becomes low (L) during other periods. However, when a determination signal indicating that the correction amount change line is an odd line is input from the odd / even line determination circuit 7, the blanking pulse generation circuit 8 performs correction as shown in FIG. A blanking pulse having a high period of one pixel after the effective display period is generated corresponding to the quantity change line. When a determination signal indicating that the correction amount change line is an even number is input, the blanking pulse generation circuit 8 displays an effective display corresponding to the correction amount change line as shown in FIG. A blanking pulse having a high period for one pixel before the period is generated. The blanking pulse generated by the blanking pulse generation circuit 8 in this manner is added to the video signal by the blanking circuit 9, and the video signal to which the blanking pulse has been added is supplied to the sample hold circuit 11. On the other hand, the horizontal compression rate determination unit 4 uses a correction amount data signal supplied from the correction amount instruction unit 3 and a signal indicating a correction amount change line supplied from the correction amount change line determination unit 2 to compress the video. In the correction amount change line, it is determined whether to increase or decrease the correction amount, and a mask pulse is generated based on the horizontal position signal output from the pixel number counter 5. Then, the clock mask circuit 6 thins out the input clock signal CLK with this mask pulse, and supplies a driving signal for compressing the video and displaying it on the liquid crystal panel 13 to the horizontal shift register 10. Here, the horizontal shift register 10 starts the horizontal driving in the display of the video signal by the start pulse input corresponding to each line, and sequentially displays the video on the liquid crystal panel 13 by the driving signal. When the horizontal scanning line correction amount is n, the start pulse is input to the horizontal shift register 10 with the phase advanced by n pixels, whereby n pixels are blocked before the video is displayed on the horizontal scanning line. The ranking will be displayed. According to the above operation, in FIG. 3 (the upper direction in the figure corresponds to the lower direction of the liquid crystal panel), when the correction amount change line is an odd number line, the pixel 31 is changed to the correction amount change line. Is an even line, an image is displayed on each of the pixels 30. As a result, the image shift between adjacent horizontal scanning lines is 0.5 pixels.
[0010]
【The invention's effect】
According to the liquid crystal display device of the present invention, when an image for correcting trapezoidal distortion is displayed on a liquid crystal panel having an arrangement shifted by 0.5 pixels for each horizontal scanning line, the image shift between adjacent horizontal scanning lines. Since the image is displayed on the LCD panel, the boundary line between the left and right blanking of the image displayed on the LCD panel is adjusted as a whole, and as a result, the right and left boundary line can be obtained even in the projected image. Can do.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of a liquid crystal display device according to an embodiment of the present invention.
FIG. 2 is a timing chart showing a blanking pulse generated by the blanking pulse generation circuit of FIG. 1;
3 is a diagram showing an image in which trapezoidal distortion displayed on the liquid crystal panel is corrected by the liquid crystal display device of FIG. 1. FIG.
FIG. 4 is a diagram for explaining trapezoidal distortion of a projected image.
5 is a diagram for explaining the principle of correcting the trapezoidal distortion of FIG. 4; FIG.
FIG. 6 is a circuit diagram showing a circuit for adding blanking in a conventional liquid crystal display device.
7 is a timing chart for explaining the operation of the circuit of FIG. 6;
8 is a diagram showing an image in which trapezoidal distortion displayed on the liquid crystal panel is corrected by the circuit of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Line counter 2 Correction amount change line determination part 3 Correction amount instruction | indication part 4 Horizontal compression rate determination part 5 Pixel number counter 6 Clock mask circuit 7 Odd / even line discrimination circuit 8 Blanking pulse generation circuit 9 Blanking circuit 10 Horizontal shift register 11 Sample hold circuit 12 Vertical shift register 13 Liquid crystal panel 14 Projector 15 Screen 16 Projected image 17 Switch

Claims (3)

A liquid crystal display device that displays an image by projecting to an external screen,
The liquid crystal display device in which a plurality of odd-th horizontal scanning lines and the even-numbered horizontal scanning lines of horizontal scanning lines has a liquid crystal panel comprising a sequence that is shifted 0.5 pixels, to display an image on the liquid crystal panel When,
A correction amount determining means for determining a correction amount based on an operation from the outside when the image projected on the screen from the liquid crystal panel has a trapezoidal distortion;
Blanking creating means for creating a blanking pulse for indicating the effective image display area and the image non-display area on the liquid crystal panel in each of front Symbol horizontal scanning lines,
Video signal creating means for adding the blanking pulse created by the blanking creating means to the liquid crystal display means by adding to the video signal;
Based on the correction amount determined by the correction amount determining means, the video signal generating means compresses the video signal to which the blanking pulse is added , and the liquid crystal display panel for each of the horizontal scanning lines A drive signal for displaying on the liquid crystal panel so that the image effective display area is narrowed by the pixel corresponding to the correction amount determined by the correction amount determination means from each of the left end and the right end of the in the liquid crystal display device that includes a compressed display means for supplying the liquid crystal display unit,
The blanking creation means
Based on the correction amount determined by the correction amount determination means, a correction amount change line determination for determining a correction amount change line for changing the correction amount with respect to the correction amount of the previous line among the plurality of horizontal scanning lines. Means,
For prior SL correction amount change line horizontal scanning line determined by the determining means, characterized in that it comprises a blanking pulse generating means for generating said blanking pulse so that spread one pixel the effective image display area A liquid crystal display device. The blanking creation means further comprises line discriminating means for discriminating whether the correction amount change line is an odd line or an even line.
The blanking pulse generating means, based on the result judged by the line determination means, film image non-display area of the correction amount changes line when arranged on the array by performing compression by said compression display means and deviation of 1.5 pixel occurs in the boundary between the movies image effective display area and boundaries and 1 line Film image non-display area and Film image effective display area of the previous horizontal scanning line is corrected to shift the 0.5 pixel The liquid crystal display device according to claim 1, wherein a portion that widens the effective image display area for one pixel is determined. The arrangement is such that the even-numbered horizontal scanning lines are shifted to the right by 0.5 pixels with respect to the odd-numbered horizontal scanning lines.
The blanking pulse generating means, based on the result judged by the line determination means, when the correction amount change line is an odd-numbered horizontal scanning lines, the position of the right edge of the movies image effective display region 1 performs correction for shifting the pixel to the right, wherein when the correction amount change line is an even-numbered horizontal scanning lines, performs correction for shifting the position of the left edge of the movies image effective display area to the left by one pixel, wherein Item 3. A liquid crystal display device according to Item 2.

Images