JPH03292088A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To display a video signal of the PAL system at a prescribed horizontal scanning thinning onto the NTSC system liquid crystal display panel by controlling the polarity of three primary color signals in the horizontal scanning before and after non-display by one horizontal scanning so as to be in the inverting relation. CONSTITUTION:An undisplay control circuit 25 eliminate a vertical start pulse DY from a timing signal generator 18 once per 7 times. Three primary color signals by 7-th horizontal scanning of one field fed from signal lines 6, 7, 8 are not applied to each picture element of a 7th line on a liquid crystal display panel 9 and not displayed, and three primary color signals by 8-th horizontal scanning are fed to each picture element of a 7-th line of the liquid crystal display panel 9. Thus, the polarity of the three primary color signals by 6th and 7th horizontal scanning periods before and after non-display on the liquid crystal display panel 9 is inverted to each other. As a result, the PAL system video signal of one field is displayed on the NTSC liquid crystal display panel 9 in color correctly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display device having a liquid crystal display panel for displaying video signals of the NTSC system, for example.

Conventionally, a liquid crystal display device for displaying, for example, an NTSC video signal has a configuration as shown in FIG. 3, (1)
is an input terminal into which an NTSC video signal is input, (2
) demodulates the three primary color signals of red, green, and blue (hereinafter referred to as rR, G, and BJ) from the video signal input from the input terminal (1) and adjusts them to match the display characteristics of the liquid crystal display panel (described later). For example, the demodulation circuit (3) generates negative polarity three primary color signals by inverting the polarity of the three primary color signals output from the demodulation circuit (2). (4) is an inverting circuit that outputs bipolar three primary color signals;
3) The three primary color signals of positive polarity (see Figure 4 (e)) and negative polarity (see Figure 4 (f)) are output from among the three primary color signals of bipolarity outputted from 3) every horizontal scanning period (IH). The alternating circuit (5) alternately outputs the bipolar three primary color signals from the alternating circuit (4). Second. The combination of R, G, and B for the third signal line (6) (7) (8) is the mosaic arrangement of the color filters of the liquid crystal display panel (
(see Figure 5), that is, R, G in each signal line (6) (7) (8) at 3H period.
, B repeats in the order of signals VIDI, VID2. VI
D3 (see FIGS. 4(r), (h), and i)). -J- (9) is 320 in the horizontal (row) direction! 240 pixels are arranged in a matrix in the vertical (column) direction, and R, G, and B color filters (10) arranged opposite to each pixel are arranged in the row and column direction. This is a TPT (thin film transistor) active matrix liquid crystal display panel with a mosaic arrangement structure arranged in this order. This liquid crystal display panel (9) has a plurality of signal electrodes (11), scanning electrodes (12), and TPT (13) on the first insulating substrate (not shown) side.
) and pixel electrodes (14) are formed in a matrix (see FIG. 6), and a common electrode is formed on the second insulating substrate (not shown), so that the common electrode and each pixel electrode (14) Display by each pixel constituted by a liquid crystal layer interposed between the T P T (13) whose source is the signal electrode (11)
The drain is connected to the pixel electrode (14) side, and the gate is connected to the scan electrode (12) side. For example, when a scan voltage is applied to the Nth row scan electrode (12), the connection is made to the Each of the T P T (13) in the Nth row becomes conductive, and the poles (11) respectively connect each signal to each pixel electrode (14) in the Nth row, and each pixel in the Nth row Signal voltages (in this case, the three primary color signals from each signal line (6), (7), and (8)) are applied respectively. Therefore,
When a scanning voltage is sequentially applied to the scanning electrodes (12) from the 1st row to the 240th row, and a signal voltage is sequentially applied to each pixel from the 1st column to the 320th column for each scanning electrode (12),
A video signal for one field can be displayed in color using 320×240 pixels.

(15) (16) is the vertical (signal electrode) drive circuit and horizontal (scanning electrode) of the liquid crystal display panel (9)! [In the dynamic circuit, the vertical drive circuit (15) applies three primary color signals from each signal line (6) (7) (8) to each signal electrode (11),
The horizontal drive circuit (16) is configured to sequentially apply a scanning voltage to each scanning electrode (12). (17) is horizontal (Fig. 4(a)) from the video signal input from input terminal (1).
)), a synchronization separation circuit for extracting the vertical synchronization signal, (1
8) is a horizontal and vertical system PLA (Programmable
Logic Array) circuit (19) (2G), vertical start pulse DY necessary for driving the liquid crystal display panel (9) (see Figure 4 (b)), vertical transfer lock C
LY, horizontal start pulse DX (see Figure 4(c)),
A timing signal generator that generates horizontal transfer lock CLX (see Fig. 4(d)), etc., and the above-mentioned alternating circuit (4).
is IH same period 1 (, horizontal transfer lock CL repeats L)
The three primary color signals of positive polarity and negative polarity are output alternately at the rising and falling timing of X, and the rotation circuit (5) outputs the IH same period vertical start pulse DY.
The combination of R, G, and B of the three primary color signals output to each signal line (6), (7), and (8) is changed based on this.

FIG. 5 shows the vertical drive circuit (15) and the horizontal drive circuit (15).
A specific configuration example of 6) is shown, and (21) is activated based on the IH same-cycle vertical start pulse DY, and outputs sequentially from left to right at the rising and falling timing of vertical transfer lock CLY. The vertical shift register (22) selects the first . Second. The three primary color signals of the third signal line (6), (7), and (8) are transferred to the first signal line. Second. The sample and hold circuit (23) is activated based on the horizontal start pulse DX with a period of one vertical scanning period (1V) and is transferred horizontally. A horizontal shift register (24
) is its buffer shift register. For example, the signals for the first horizontal scan of one field supplied from each signal line (6) (7) (8) are processed by the alternating circuit (4) and rotation circuit (5) to The signal line (6) is the R signal, the second signal line (7) is the G signal, and the third signal line (8) is the B signal (see Figure 4), which are selected by the horizontal shift register (23). R and G are applied to each pixel in the first row of the liquid crystal display panel (9) from left to right by a vertical shift register (21) and a sample hold circuit (22).

From left to right to correspond to the mosaic arrangement of color filters (10) in the order of B (repeat the order of R, G, B)
will be applied.

(However, in a liquid crystal display device with such a configuration, N
When trying to display PAL video signals instead of TSC video signals, it is necessary to increase the vertical size of the liquid crystal display panel to account for the increased number of horizontal scanning lines.
The size remained the same, but the vertical pixel pitch had to be narrowed. However, in the former case, for example, a camera-integrated VT that requires a smaller LCD panel
This is not preferable for use in an R viewfinder, and in the latter case, the aperture ratio decreases, resulting in a loss of image quality (i1 surface becomes dark and low contrast). In addition, by increasing the processing accuracy of the electrode, the TP
It may be possible to improve the decrease in aperture ratio by implementing higher density mounting of T, color filters, etc., but in the case of small liquid crystal display panels for viewfinders, the pixel pitch is about 6 On and the electrode width is about Lon. It is technically difficult to manufacture.

The present invention has been developed in view of these points, and is
A liquid crystal display in which a liquid crystal display device used for displaying TSC system video signals can be used for displaying PAL system video signals without changing the screen size and pixel pitch of the NTSC system liquid crystal display panel. The purpose is to provide equipment.

In order to achieve the above object, the present invention comprises a plurality of pixels, a plurality of signals, and a scanning electrode arranged in a matrix, and R and CB color filters arranged opposite to each pixel. R
, G, and B, in which three primary color signals of R, G, and B are transmitted to each signal electrode in a combination according to the mosaic arrangement of the color filters. signal control means for outputting the three primary color signals and inverting the polarity of the three primary color signals every horizontal scanning period; The present invention is configured to include non-display control means for controlling the signal control means so that the polarities of the three primary color signals during scanning are inverted to each other.

Tachi-Sato: With such a configuration, for example, a PAL video signal is thinned out and displayed at predetermined horizontal scanning intervals on a liquid crystal display panel for the NTSC system. Furthermore, since the polarities of the horizontal scanning lines before and after the check mark on the liquid crystal display panel are inverted, a display without line flicker can be achieved.

叉”L group An embodiment of the present invention will be described below with reference to the drawings.

It should be noted that the same parts as those in the prior art will be given the same reference numerals and the explanation thereof will be omitted.

In this embodiment, for example, if the number of pixels in the vertical direction required by a PAL liquid crystal panel is 280, three primary color signals for one horizontal scan are left undisplayed every seven horizontal scans, as shown in FIG. By providing a non-display control circuit (25) that does not display the three primary color signals for 40 horizontal scans in one field, the NTSC liquid crystal display panel with 240 pixels can be converted into a PAL display panel. It is designed to be used for signal display.

Specifically, the non-display control circuit (25) outputs the vertical start pulse DY from the tie signal generator (18) once every seven times.
(see Fig. 2 (b)), and based on this, the horizontal transfer lock CLX is held at the H level state immediately before non-display while it is not displayed (see Fig. 2 (d))
It looks like this.

Therefore, first, the three primary color signals for the first to sixth horizontal scans of one field supplied from each signal line (6) (7) (8) are vertical as described above.

The horizontal drive circuit (i5) (16) applies the voltage to each pixel from the first row to the sixth row of the liquid crystal display panel (9). However, for the three primary color signals for the seventh horizontal scan that are supplied next, the vertical shift register (21) of the vertical drive circuit (15) is not activated due to the removal of the vertical start pulse DY, and the horizontal drive circuit (16) is not activated. Since the horizontal shift register (23) keeps the horizontal transfer lock CLX at H level and the scanning electrode on the 6th row remains selected, the voltage is applied to each pixel on the 7th row of the liquid crystal display panel (9). The data is not displayed (the seventh horizontal scanning line of one field is thinned out).

Then, the three primary color signals for the 8th horizontal scan supplied from the signal lines (6) (7) (8) are applied to the next vertical start pulse DY and the horizontal transfer lock C based on the next vertical start pulse DY.
As LX falls, the voltage is applied to each pixel in the seventh row of the liquid crystal display panel (9).

During this thinning, the horizontal transfer lock CLX maintains the same H level state as during the sixth horizontal scan and does not fall, keeping the alternating circuit (4) in a state in which it outputs negative polarity. Therefore, the polarities of the three primary color signals for the sixth and seventh horizontal scans before and after non-display on the liquid crystal display panel (9) are inverted with each other. Furthermore, during this thinning, the rotation circuit (5) also maintains the same combination of R, G, and B as in the sixth horizontal scan by removing the vertical start pulse DY (see Figure 2), so the liquid crystal display The combination of R, G, and B of the three primary color signals for the seventh horizontal scan after non-display on the panel (9) is determined by the color filter (lO
) will correspond to the mosaic array. Thereafter, by similarly not displaying the three primary color signals for one horizontal scan every seven horizontal scans, and leaving the three primary color signals for 4o horizontal scans undisplayed as a whole, the liquid crystal display panel (9) for the NTSC system has one
It is possible to correctly display the PAL video signal of the field in color.

As mentioned above, according to the liquid crystal display device of the present invention, the NTSC
The liquid crystal display panel used to display video signals of
P without changing the screen size and pixel pitch
Since the AL system video signal can be correctly displayed as a color sandwich without line flicker, it is suitable for use, for example, in the viewfinder of a camera-integrated VTR, which requires a smaller liquid crystal display panel.

[Brief explanation of drawings]

Fig. 1 is a block circuit diagram of a liquid crystal display device embodying the present invention, Fig. 2 is a signal waveform diagram of each part thereof, Fig. 3 is a block circuit diagram of a conventional liquid crystal display device, and Fig. 4 is a signal waveform diagram of each part thereof. FIG. 5 is a diagram showing a specific configuration of the main part of the waveform diagram, and FIG. 6 is a diagram showing an example of the electrode structure of the liquid crystal display panel. (3)...Inversion circuit, (4)...Alternating circuit. (5)... Rotating tangent circuit. (9)...Liquid crystal display panel, (10)...Color filter (18)...Timing signal generation circuit. (25)...-undisplayed control circuit.

Claims (1)

[Claims] (1) A plurality of pixels, a plurality of signals, and a scanning electrode are arranged in a matrix, and red, green, and
In a liquid crystal display device having a liquid crystal display panel having a mosaic arrangement structure in which blue color filters are arranged in the order of red, green, and blue, red and green are arranged on each signal electrode in a combination according to the mosaic arrangement of the color filters. , a signal control means that outputs the three primary color signals of blue and inverts the polarity of the three primary color signals every horizontal scanning period; A liquid crystal display device comprising a non-display control means for controlling the signal control means so that the polarities of the three primary color signals in horizontal scanning before and after the non-display are inverted.