JPH05122641A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide high quality image display after thinning scanning lines by prevent one scanning line from being frequently and apparently thinned and providing a thinning controller withing a driving circuit. CONSTITUTION:A driving circuit 3 provided with a thinning controller 1 and a panel controller 2, a liquid crystal display element 7 provided with a scanning line driver IC 4, a signal line driver IC 5 and a liquid crystal panel 6, and a changeover switch 8 are provided. When the changeover switch 8 is turned on by an operator, the thinning controller 1 is synchronized with the fall of an externally inputted vertical synchronization signal to thin the scanning lines from an image signal inputted to the panel controller 2. That is, by preventing the scanning lines to be thinned from being biased in bottom face arrangement and preventing the same scanning line from being thinned twice or more within a period of three fields to be biased in time arrangement, the thinning can be prevented from being apparent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having an XY matrix type liquid crystal display element.

[0002]

2. Description of the Related Art Television standard systems currently in use worldwide are roughly divided into N and US
There are TSC system, PAL system in Western Europe, SECAM system in France, USSR and Eastern Europe.

Of these, the number of scanning lines in the NTSC system is 5
In contrast to the 25 lines, the PAL system and SECAM system have 625 scanning lines, and the NTSC system has 100 fewer scanning lines than the other two systems.

Therefore, for example, when displaying a PAL television image signal of Western Europe on an NTSC television receiver of Japan through an artificial satellite relay,
Using a kind of digital scan converter called a TV standard converter at a relay station, PAL scan lines are thinned to about 5/6 from 625 scan lines to 525 NTSC scan lines. Thus, the PAL system image signal is converted to the NTSC system television receiver.

The image signal obtained by thinning out the scanning lines of the image signal as described above is one in which about one out of every six scanning lines of the original image signal is missing.
The image displayed based on this also lacks image information corresponding to the thinned scanning lines.
Further, in this case, if the scanning lines at the same position in each field are thinned out, the displayed image is
There is a problem that flicker, flicker, and stripe-shaped uneven display flow occur.

Therefore, in order to solve such a problem, in the conventional television standard conversion device, one is selected from every six adjacent scanning lines, and the scanning line positions to be thinned out in two consecutive fields are selected. The adjacent scan lines are alternately shifted.

However, even if such a thinning method of scanning lines is adopted, although the problems such as the flicker, the flicker, and the flow of display unevenness in stripes as described above are almost eliminated with respect to a moving image, it is still. As for the image, since there is no motion in the image, the flow of flicker, flicker, and striped display unevenness due to the lack of image information corresponding to the thinned scan lines as described above is visually recognized, making the image difficult to see. was there.

By the way, in recent years, liquid crystal display devices have come to be used as portable televisions. When used as this portable television, it is considered that there are many opportunities to take it out overseas to receive the television image signal of the standard system of the area due to its characteristics suitable for carrying. However, when it is used in an area where the standard system is different as described above, for example, in the case where it is a specification that is basically sold and used in Japan, there is a problem if it is in an area where the NTSC system is adopted. Not PA
Since the number of scanning lines is different in the area where the L system is adopted, it is impossible to receive the television image signal and display the image.

Therefore, for example, in a portable television using a liquid crystal display device adopting such an NTSC system, a device simplified from the above digital scan converter is provided inside, and a PAL system or the like is provided. There is known a method of converting the image signal so as to be compatible with the NTSC system by thinning out the scanning line of the image signal.

However, even in a portable television using such a liquid crystal display device, as in the case of the conversion of the standard system of the conventional general television as described above, the PA is used.
When the scanning lines of the image signal of the L system are thinned out and converted into the image signal of the NTSC system, the flow of flicker, flicker, and striped display unevenness is visually recognized, and the image is difficult to see. .. This becomes even more remarkable in a portable television using a liquid crystal display device which is smaller in size and lower in definition than a conventional general television.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an object of the present invention is to thin out the scanning lines of the PAL system image signal to obtain N lines.
When converting to an image signal such as the TSC system, it is possible to eliminate the flicker, flicker, and striped flow of display unevenness that is not visible on the display image. An object of the present invention is to provide a liquid crystal display device which can display image signals of different standard systems such as signals and which does not deteriorate the quality of the displayed image and which is used for image display applications such as a portable television.

[0012]

A liquid crystal display device according to the present invention has an XY matrix type liquid crystal display element, and has a predetermined number of scanning lines selected at regular intervals from an input image signal. In a liquid crystal display device having a drive circuit for thinning out each field and displaying an image on the liquid crystal display element, the predetermined number of scanning lines to be thinned out in one field are arranged so that at least two scanning lines are arranged. In addition, it is characterized by comprising a drive circuit for selecting and thinning out the same scanning line at a time interval of at least two fields.

[0013]

When a plurality of adjacent scanning lines are thinned out at once in one field, or when the same scanning line is continuously thinned out over a plurality of fields, the image information corresponding to the thinned scanning lines is lost. As a result, the flow of flicker, flicker, and striped display unevenness becomes noticeable in the displayed image.

Therefore, the thinning scan lines are arranged in one field with a space between at least two adjacent scan lines, that is, at least two scan lines are arranged between thinning scan lines. To make the thinned scan lines inconspicuous in the planar arrangement of the screen, and select the same scan line at a time interval of at least two fields, that is, at least thin lines. 3
Make sure that the same scanline is not decimated more than once within the time of the field, so that one scanline is frequently culled and is not conspicuous.

As described above, by arranging the scanning lines to be thinned out on the screen so as not to be biased in terms of both plane and time, it is possible to suppress the flicker of the display image and the manifestation of the flow of flicker or striped display unevenness. Then, high-quality image display after thinning the scanning lines is realized.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid crystal display device of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration of a liquid crystal display device of the present invention, and FIG. 2 is a circuit diagram showing a configuration of a main part of a thinning controller thereof.

As shown in FIG. 1, the liquid crystal display device of the present invention has a drive circuit 3 having a thinning controller 1 and a panel controller 2, a scanning line driver IC 4, a signal line driver IC 5 and a liquid crystal display panel 6. The liquid crystal display element 7 and the changeover switch 8 are provided.

The drive circuit 3 is a drive circuit for a liquid crystal display device having a thinning controller 1 and a panel controller 2, and adopts an NTSC system as a standard system.

When the changeover switch 8 is turned ON by the user, the thinning controller 1 operates in synchronization with the falling edge of the vertical synchronizing signal input from the outside, and operates from the image signal input to the panel controller 2 Scanning lines are thinned out.

As shown in FIG. 2, this thinning-out controller 1 has an LFSR (LSR using three flip-flops.
inner Feed Back Shift Res
4), each Q output of the flip-flops Fa, Fb, and Fc is driven by D, as shown in the timing chart of FIG.
If 0, D1 and D2 are set, these are output as 3-bit binary data and sent to the panel controller 2.

The panel controller 2 receives a vertical synchronizing signal, a horizontal scanning signal and an image signal inputted from the outside, and the timing of applying the liquid crystal driving voltage to the scanning line driver IC 4 and the signal line driver IC 5 of the liquid crystal display element 7 and its timing. Control the pulse voltage.

An image signal having a large number of scanning lines, such as the PAL system, input from the outside is generated by the panel controller 2.
Output D from the thinning controller 1 at
The scanning lines are thinned by being controlled by 0, D1, and D2, and are sent to the liquid crystal display element 7.

The liquid crystal display element 7 is a scanning line driver IC 4
A simple matrix type liquid crystal display device having a signal line driver IC 5 and a liquid crystal display panel 6. The structure and the circuit configuration of the driver IC are the same as those generally used.

In the liquid crystal display element 7, the scanning line driver IC 4 and the signal line driver I are based on the image signals or the like sent by thinning the scanning lines from the panel controller 2.
C5 applies a liquid crystal drive voltage to the liquid crystal display panel 6. Then, the liquid crystal display panel 6 displays an image.

Next, the operation of the liquid crystal display device of the present invention will be described.

FIG. 4 is a diagram showing the arrangement of thinned scanning lines in each field. In FIG. 4, scanning lines thinned out in each field are indicated by circles.

In the thinning controller 1 and the panel controller 2 in the drive circuit 3, a set of 3 bits of 6-state binary data (0,
0,0), (1,0,0), (1,1,0), (1,0,1), etc. are the positions of the scanning lines thinned out for each field shown in FIG. Corresponding to 301, 302, 304, 306 ..., Based on such 3-bit binary data, the panel controller 2 thins out the scanning lines for each field at the timing and arrangement shown in FIG.

As is apparent from FIG. 4, the thinning method of such scanning lines is performed by sequentially scanning the scanning lines 301, 302, 3 in sequence.
04, 306, 303, 305 ... In this order, the thinning order is such that one skip is woven in such a manner that one line is thinned out for each field, and the thinning scanning line for each field is arranged in, for example, n fields. The scanning lines 301, 307, 313, ... Are arranged every six scanning lines at intervals of five scanning lines.

That is, if the vertical axis represents the vertical position of the scanning line as Y and the horizontal axis represents the first to sixth fields as n, the relationship between the position Y and the field n is The first and second fields are represented by Y = n, followed by Y = 2n−2 from the second field to the fourth field, and Y = −3n + 18 from the fourth field to the fifth field, and the fifth field. The field and the sixth field can be expressed as Y = 2n−7,
In this way, the rules that determine the order of selecting scan line positions to be thinned out for each field within all six fields are changed three times. In this embodiment, as described above, the scanning lines are thinned out by changing the position of the scanning lines to be thinned out according to a rule rather than randomly. Flickering is not noticeable because it is not thinned more than once. Further, the flow of the striped pattern of the display unevenness due to the movement of the thinning position in one direction, such as the case of simply thinning the lines in sequence, is hardly noticeable. It is also possible to prevent accidental deviation of the positions of the thinning-out scanning lines caused by randomly moving the thinning-out positions.

The vertical arrangement of the thinning scanning lines in one field is such that five thin scanning lines are spaced between the thinning scanning lines as shown in FIG.
This is repeated evenly in the vertical direction over the entire 50 lines / field of the thinned scan lines, and is arranged at intervals of 5 lines with a ratio of 1 to 6 lines, so that the thinned scan lines are arranged in a plane of the screen. Arranged evenly in the array,
It has become inconspicuous.

As described above, in the liquid crystal display device of the present invention, the thinned scan lines are not biased in the planar arrangement of the screen, and the same scan line is frequently twice or more within the time of at least 3 fields. The scanning lines are thinned out so that there is no bias in the temporal arrangement so that the thinning out of the scanning lines is inconspicuous.

In this embodiment, the case where the PAL system image signal is converted to the NTSC system is shown, but the present invention is not limited to this.

For example, in the standard system, in addition to the PAL system, SE
Even in the case of the CAM method, the conversion can be performed by the same action.

The present invention can be applied not only to a television image signal, but also to other image signals having a different number of scanning lines, such as a display device of a personal computer or a computer graphics display. it can.

However, in these cases, it goes without saying that the number of scanning lines to be thinned out must be appropriately changed in accordance with the total number of scanning lines of the image signal before conversion.

[0036]

As described above in detail, in the liquid crystal display device of the present invention, when the scanning lines of the PAL system image signal are thinned out and converted into the NTSC system image signal, the scanning lines to be thinned out are selected. By arranging the image on the screen without any deviation in terms of plane and time, it is possible to suppress the flicker of the displayed image, the occurrence of flicker and stripe-like uneven display flow, and the high-quality image after thinning the scanning lines. It is possible to realize the display.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a liquid crystal display device of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a main part of a thinning controller included in the liquid crystal display device of the present invention.

FIG. 3 is an operation timing chart of main parts of a thinning controller included in the liquid crystal display device of the present invention.

FIG. 4 is a diagram showing an arrangement of thinned scanning lines in each field in the liquid crystal display device of the present invention.

[Explanation of symbols]

 1 ... Thinning controller 2 ... Panel controller 3 ... Drive circuit 4 ... Scan line driver IC 5 ... Signal line driver IC 6 ... Liquid crystal display panel 7 ... Liquid crystal display element 8 ... Changeover switch

Claims (1)

[Claims] 1. An XY matrix type liquid crystal display device, wherein a predetermined number of scanning lines selected at regular intervals from an input image signal are thinned out for each field to display an image on the liquid crystal display device. In a liquid crystal display device having a driving circuit for displaying, the predetermined number of scanning lines to be thinned out in one field are arranged so that at least two scanning lines are spaced apart from each other,
A liquid crystal display device comprising a driving circuit for selecting and thinning out the same scanning line at a time interval of at least two fields.