JP3332437B2 - Image display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image display device in which pixels are arranged in a matrix, and more particularly, to an image display device in which the image quality of a displayed image in the vertical direction is small.

[0002]

2. Description of the Related Art Conventional liquid crystal displays an image using liquid crystal.
The display device is disclosed, for example, in Japanese Patent Publication No. 1-331346.
You. FIG. 6 shows an image displayed by a conventional liquid crystal display device.
It is a conceptual diagram in the case. Conventional liquid crystal display devices
The number of arranged pixels is small. Therefore, Fig. 6 (a) shows
When displaying the original image A, the video signal of one frame of the original image A is displayed.
Issue odd field F₁, F_Three, F_Five, F₇, F₉When,
Even field F_Two, F_Four, F₆, F₈, F _TenVideo signal
Are horizontally and vertically arranged on the liquid crystal panel P shown in FIG.
Feel the same pixels Q, Q, Q ... arranged in a row.
The images are displayed by giving them alternately for each command.

[0003]

When an image is displayed in this manner, an odd field and an even field which should be displayed at a position shifted by one horizontal scanning line in the vertical direction. The display image of the field is alternately displayed by the same pixel. Therefore, the display image fluctuates in the vertical direction at a cycle of about 30 Hz which is the field cycle. Therefore, there is a problem that image quality deterioration more than simply halving the number of scanning lines occurs in the vertical direction of the display image, and a high-quality display image cannot be obtained. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an image display device in which the image quality of a display image in the vertical direction is small.

[0004]

According to the present invention, there is provided an image display apparatus comprising: a video signal of one field of a video signal of one frame which is interlacedly scanned on the same pixel arranged horizontally and vertically in a matrix; In an image display apparatus that alternately supplies a signal and a video signal of the other field to display an image, the image display device includes an interpolation filter that obtains a video signal obtained by interpolating a video signal of an adjacent scanning line in a predetermined field, An interpolated video signal output from the interpolation filter and a video signal of a field not interpolated by the interpolation filter are alternately applied to the same pixel.

[0005]

When a video signal of a predetermined field of a video signal of one frame is supplied to an interpolation filter, the interpolation filter interpolates video signals of adjacent scanning lines in the predetermined field and outputs an interpolated video signal. An image is displayed by alternately applying the video signal of the field in which the video signal is not interpolated and the video signal of the field interpolated by the interpolation filter to the same pixel. As a result, the change in the video signal applied to the same pixel can be reduced, and the image quality is improved.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. FIG. 1 is a block diagram showing a configuration of a main part of a liquid crystal image display device as an image display device according to the present invention. FIG. 1 shows a configuration of a liquid crystal display device for displaying black and white for convenience.
The video signal S is supplied to a vertical interpolation filter 1 and a fixed contact 2a on one side of a switch 2 serving as a switching unit. The vertical interpolation filter 1 is configured to interpolate, for example, video signals of adjacent scanning lines in an even field of a video signal of one frame and output an interpolated video signal.

The video signal output from the vertical interpolation filter 1 is given to the other fixed contact 2b of the changeover switch 2. The video signal selected by the switching contact 2c that performs a switching operation to select the fixed contacts 2a and 2b of the changeover switch 2 is given to the liquid crystal panel P. The changeover switch 2 is configured such that the switching contact 2c switches to the fixed contact 2b side in an even field, and switches to the fixed contact 2a in an odd field.

FIG. 2 is a block diagram showing a main configuration of an image display apparatus using a vertical interpolation filter 1 for performing linear interpolation. The vertical interpolation filter 1 delays one horizontal period 1H
It comprises a 1H delay element 10, an adder 11, and a 倍 -fold amplifier 12. The video signal S is supplied to the 1H delay element 10, the adder 11, and the fixed contact 2a on one side of the changeover switch 2. The video signal output from the 1H delay element 10 is input to the adder 11. The video signal output from the adder 11 is input to the 1/2 amplifier 12, and the video signal output from the 1/2 amplifier 12 is applied to the other fixed contact 2b of the changeover switch 2. The video signal selected by the changeover contact 2c of the changeover switch 2 is supplied to the liquid crystal panel P. Changeover contact of changeover switch 2
2c is configured to switch to the fixed contact 2b side in the case of an even field and to the fixed contact 2a side in the case of an odd field.

Next, the operation of the liquid crystal display device will be described.
The video signal S input to the vertical interpolation filter 1 is such that the switching contact 2c of the changeover switch 2 is a fixed contact 2a in an odd field.
To the liquid crystal panel P via the switch 2. In even field, switching contact 2c is fixed contact
Switching to the 2b side, the adder 11 adds the video signal of the previous scan line and the video signal of the current scan line, which is delayed by one horizontal period 1H by the 1H delay element 10 of the vertical interpolation filter 1, to the adder 11. The video signal is input to the 1/2 times amplifier 12, and the 1/2 times amplifier 12
A video signal obtained by doubling and averaging, that is, a video signal obtained by weighted averaging and interpolating video signals of adjacent scanning lines is supplied to the liquid crystal panel P, and an image is displayed on the liquid crystal panel P.

FIG. 3 shows an image displayed as described above.
FIG. Odd number as explained by FIG.
Field F₁, F_Three, F_Five, F₇, F₉Then, the video signal
Is given to each pixel Q, Q, Q... Of the liquid crystal panel P as it is.
Drive the pixels Q, Q, Q,... Of the liquid crystal panel P.
You. On the other hand, even field F_Two, F_Four, F₆, F₈, F
_TenNow, the vertical interpolation filter 1 is used to scan adjacent scanning lines.
The video signal obtained by linearly interpolating the video signal is
Are applied to the same pixels Q, Q, Q,.
You. In this manner, the same pixels Q, Q, Q.
With this, the video signal of the even field is converted to the odd field.
Of the displayed image
Can be reduced.

On the other hand, the state of driving a pixel using such a linearly interpolated video signal can be expressed as shown in FIG. In FIG. 4, the vertical axis is a video signal, and the horizontal axis is a scanning line. The S-shaped solid line indicates, for example, a video signal in the vertical direction of the original image. And the video signal of the odd field is marked with □, the video signal of the even field is marked with ○,
The interpolated video signal is indicated by a cross. As is apparent from FIG. 4, in the even-numbered field, an interpolated video signal of X is obtained, and the same pixel Q driven by the video signal of □ in the odd-numbered field is driven by the interpolated video signal of X. As a result, the difference between the video signals for driving the same pixel for each field can be reduced.

Thus, it is possible to prevent the image quality from deteriorating beyond the image quality of the display image when the image is displayed at a position shifted by one scanning line in the vertical direction between the odd field and the even field. This makes it possible to reduce the image quality degradation in the vertical direction of the image displayed on the panel.

A similar effect can be obtained by applying a video signal directly to the liquid crystal panel P in an even field and supplying a video signal output from the vertical interpolation filter 1 to the liquid crystal panel P in an odd field. Here, the case where the vertical interpolation filter for performing the linear interpolation is used has been described, but an interpolated video signal closer to the true value may be obtained by using a high-order filter having a large number of taps.

Although the liquid crystal display device for displaying an image in black and white has been described with reference to FIG. 2, deterioration of image quality can be reduced by a similar configuration for a liquid crystal display device for displaying an image in color. In such a case, a vertical interpolation filter may be used for each color signal unit, and a configuration in which the vertical interpolation filter is applied only to the video signal by utilizing the fact that the resolution required for the video signal and the color difference signal is different. You may.

By using the vertical interpolation filter in this way, it is possible to reduce the deterioration of the image quality of a color-displayed image, but the price is increased by the price of the vertical interpolation filter. By the way, in the liquid crystal display device of the color display by the NTSC system,
In order to separate a video signal and a color signal, it is becoming common to use a correlation in a direction orthogonal to the time axis of the video signal. This is a so-called comb filter. In this comb filter, one horizontal period 1H is used in order to take a correlation in a direction orthogonal to the time axis of the video signal.
Are used. Therefore, by using this delay element in common with the above-described 1H delay element of the vertical interpolation filter, it is possible to realize an NTSC liquid crystal display device that can reduce the image quality deterioration without increasing the cost.

FIG. 5 is a block diagram showing a main configuration of an NTSC type liquid crystal display device. Composite video signal by NTSC system
CS is input to the 1H delay element 10, adder 11, adder 14, and adder 17. The output signal of the 1H delay element 10 is input to the adder 11 and the inverting amplifier 13, and the output signal of the inverting amplifier 13 is input to the adder 14. The output signal of the adder 11 is a 1/2 times amplifier
Entered into 12. The output signal of the 1/2 amplifier 12 is applied to a fixed contact 2b of the switch 2. The output signal of the adder 14 is 1 /
The signal is input to the double amplifier 15. A chrominance signal is output from the × amplifier 15. This color signal is input to the inverting amplifier 16. The output signal of the inverting amplifier 16 is input to the adder 17, and the output signal of the adder 17 is given to the fixed contact 2a of the changeover switch 2.

The changeover contact 2c of the changeover switch 2 is a fixed contact 2
The switching operation is performed to the a and 2b sides. In the case of an even field, the switching operation is switched to the fixed contact 2b side, and in the case of the odd field, the switching operation is switched to the fixed contact 2a side.

Next, the operation of the NTSC type liquid crystal display device will be described. This liquid crystal display device utilizes the property that the carrier waves of the chrominance signals have opposite phases in order to separate the video signals and the chrominance signals from the composite video signal CS of the NTSC system. Therefore, the color signal is combined with the composite video signal of the current scanning line,
The composite video signal of the scanning line 1H before one horizontal period delayed by the delay element 10 and inverted and amplified by the inverting amplifier 13 is added by the adder 14, and amplified by 1/2 times by the times amplifier 15. Can be obtained.

On the other hand, the video signal is added by the adder 3 to the composite video signal of the current scanning line and the composite video signal of one horizontal period 1H before. 1 /
It can be obtained by two-fold amplification. Further, it can be obtained by adding a composite video signal of the current scanning line and a signal obtained by inverting and amplifying a color signal separated therefrom by an inverting amplifier 16. The video signal obtained from the half amplifier 12 is the average of the video signals of adjacent scanning lines, whereas the video signal obtained from the adder 17 is the video signal of the current scanning line itself. It has become.

Therefore, by selecting these two video signals by the changeover switch 2 in accordance with the odd field and the even field, as in the case of the liquid crystal display device for displaying black and white described above, one signal is used for the odd field and the even field. It is possible to prevent the image quality from deteriorating beyond the image quality of the display image when the image is displayed at a position shifted in the vertical direction by the image of the scanning line, and to reduce the vertical image quality deterioration of the color image displayed on the liquid crystal panel. Since the delay element used to separate the video signal and the color signal is shared with the 1H delay element of the vertical interpolation filter,
The price increase due to the price of the 1H delay element can be avoided. In addition,
The same configuration can be applied to a video / color separation filter having a large number of taps.

The present embodiment can be applied to a single-panel liquid crystal display device using a single liquid crystal panel, and also to a liquid crystal display device using a plurality of liquid crystal panels to optically combine images. Applicable. Further, the present invention is not limited to a device for driving a liquid crystal panel, and can be applied to an image display device in which a predetermined number of display elements are horizontally and vertically arranged in a matrix like the liquid crystal panel.

Further, the embodiment may be applied as an analog signal, or may be applied after being converted into a digital signal. Note that the changeover switch used in this embodiment is an example, and an analog switch that does not depend on the contact structure may be used.

[0023]

As described in detail above, the present invention includes an interpolation filter for interpolating video signals of adjacent scanning lines, and outputs an interpolated video signal output from the interpolation filter and a non-interpolated video signal. Since the signal and the signal are alternately applied to the same display element for each field, the signal change of the video signal applied to the same display element for each field can be reduced.
It is possible to provide an image display device capable of displaying a high-quality image by reducing deterioration of the image quality in a vertical direction of a display image. In a color display image display device, the delay element used for separating the video signal and the color signal is shared with the delay element of the vertical interpolation filter, so that the vertical interpolation filter can be formed at low cost.
An excellent effect is obtained such that a color display image display device can be provided at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a liquid crystal display device according to the present invention.

FIG. 2 is a block diagram illustrating a main configuration of a liquid crystal display device to which a vertical interpolation filter using linear interpolation is applied.

FIG. 3 is a conceptual diagram when an image is displayed.

FIG. 4 is an explanatory diagram showing a relationship between a video signal of each field and an interpolated video signal.

FIG. 5 is a block diagram showing a main configuration of an NTSC liquid crystal display device.

FIG. 6 is a conceptual diagram when an image is displayed on a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vertical interpolation filter 2 Changeover switch 10 1H delay element 11 Adder 12 1/2 times amplifier P Liquid crystal panel

Claims (2)

(57) [Claims] 1. A video signal of one field and a video signal of the other field of a video signal of one frame interlacedly scanned are alternately arranged on the same pixel arranged in a matrix in a horizontal and vertical manner. In an image display device that is configured to display an image by giving an image signal obtained by interpolating an image signal of an adjacent scanning line in a predetermined field, an interpolated image signal output from the interpolation filter is provided. An image display device, wherein a video signal of a field for which interpolation is not performed by an interpolation filter is alternately applied to the same pixel. 2. A delay unit for delaying a video signal for forming the interpolation filter and a delay unit for separating a luminance signal and a chrominance signal from a composite video signal. The image display device according to claim 1, wherein: