JPS603698A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a liquid crystal display device for, for example, television reception.

Background Art and Problems There have been proposals to display television images using, for example, a liquid crystal.

In FIG. 1, (1) is an input terminal to which a television video signal is supplied, and the signal from this input terminal (1) is transmitted to each switching element M1. M2...Line L1 in the vertical (Y-axis) direction through Mm. L2...supplied to Lm. Note that m is a number corresponding to the number of pixels in the horizontal (X-axis) direction. Furthermore, an m-stage shift register (2) is provided, and this shift register (2) receives clock signals φ, H, which have m times the horizontal frequency.
+ Φ2H is supplied, and drive pulse signals φH1+ φH2 are sequentially scanned by clock signals ΦiH1Φ2H from each output terminal of this shift register (2).
The φ song is supplied to each control terminal of switching elements M1 to Mm. Note that the shift register (2) has a low potential (Vss
) and a high potential (V oo ) are supplied, and drive pulses of these two potentials are formed.

Further, each line L1 to Lm is provided with a switching element M s'x consisting of, for example, an N-channel F E 'I'.
+M21...Mn11M12IM22...Mn2.
...M 1. , M2. ...One end of Mnm is connected. Note that n is a number corresponding to the number of horizontal scanning lines.

The other ends of the switching elements M1'1 to Mnm are respectively connected to the liquid crystal cells C1'1. C21... are connected to the target terminal'(3) through Cnm.

Furthermore, an n-stage shift register (4) is provided, and this shift register (4) receives a horizontal frequency clock signal ΦIV.
+ Φ2v is supplied, and the drive pulse signal φV1+ ψv2 is sequentially scanned by the clock signal ΦiVr Φ2v from each output terminal of this shift register (4).
・φvn is X of switching element M1'1~Mnm
Each column in the axial direction (It/hl-Mun), (M2t~M
211) ...(Mn1 to Mnm) are respectively supplied to the control terminals of the terminals. Incidentally, Vss and ■DD are also supplied to the shift register (4) in the same way as the shift register (2).

That is, in this circuit, the shift register (2).

(4) The lock signal Φ1 is as shown in Fig. 2A and B.
)1+φ2H1φ, V, φ2v are supplied. Then, the shift register (2) outputs φH1 to φ1 (Ill) for each pixel period as shown in FIG. 2C, and the shift register (4) outputs φヮ, ~φvn is output.Furthermore, the input terminal (
1) is supplied with a signal as shown in FIG. 2E.

When φVt+ φ□□ is output, switching elements M1 and M11 to M1m are turned on, and input terminal (1) = M 1- L 1- M□1- C1'
A current path from 1 to the target terminal (3) is formed, and the potential difference between the signal supplied to the input terminal (11) and the target terminal (3) is supplied to the liquid crystal cell C1'1. A charge corresponding to the potential difference caused by the signal of the first pixel is sampled and held in the capacitance of .The light transmittance of the liquid crystal is changed according to the amount of charge.The same thing is true for cells C12 to Cnm. are performed sequentially for each cell C, and when the next field signal is supplied
The charge amount of 14 to Cnm is rewritten.

In this way, the light transmittance of the liquid crystal cells C1'x to Cnm is changed corresponding to each pixel of the video signal, and this is sequentially repeated to display a television image.

When displaying on a liquid crystal display, alternating current driving is generally used to improve reliability and longevity. For example, in the display of television images, 1 frame 1 yield or 1
The input terminal (
1). That is, the input terminal (11) is supplied with a signal that is inverted for each field or frame as shown in FIG.

By the way, in the above-mentioned device, for example, one transmission type liquid crystal cell C is constructed as follows. In Figure 3,
A shows a plan view, and B shows a sectional view taken along line 8-A. In the figure, (20) is a glass substrate, and this glass substrate &(2
0) A gate line (21) made of a transparent electrode is provided on the
A 5ISSL film (22) is provided on the gate line (21) and on the entire surface of the glass substrate IM (20). In addition, 5tCh1 time (
An amorphous silicon layer (23) is provided on both sides of the amorphous silicon layer (22), and a vertical signal line (24) made of metal such as aluminum is provided on the left side of this silicon layer (23) in the drawing, corresponding to the above-mentioned lines L5 to Ln. It will be done. Also, the silicon layer 12
A pixel electrode (26) made of a 'ζ transparent electrode is provided on the right side of the drawing in 3) with a metal layer (25) interposed therebetween. A Si32 layer (27
) is provided. A liquid crystal (28) is provided on this 5i02 layer (27), and a target electrode (29) made of a transparent electrode and a protective glass (3o) are provided thereon.

Therefore, in this device, when a signal is supplied to the signal line (24) and the gate line (21) has a surface potential, the signal line (24)
4) is supplied to the metal M (25) through the silicon layer (23) and is stored in the capacitive component formed between the metal layer (25) and the signal line (24). This stored signal is then supplied to the pixel electrode (26), and the liquid crystal (2) is adjusted according to the potential difference with the target electrode (29).
8) The light transmittance is changed.

However, in this case, the signal line (24) and the metal layer (25)
A coupling capacitance is formed between -h, and through this coupling capacitance,
cYY axis direction signal crosstalk occurs. In other words, when there is a figure A in FIG. 4, when a signal is supplied to the corresponding line Ls-LL in the Y-axis direction, it is connected to other liquid crystal cells (C1s"Cn5) in the Y-axis direction through the coupling capacitance.
A signal is also supplied to ~(C1t"Cnt), and crosstalk occurs on both sides of the Y axis.Furthermore, the amount of crosstalk is
If the memory capacity of the cell is CM and the coupling capacitance is c's, then it corresponds to the value S CM + CS, and if the pixel area is made smaller, the memory capacity CM becomes smaller, while the coupling capacitance Cs is almost constant. Therefore, crosstalk becomes large.

Furthermore, when AC driving is performed as described above, a signal of opposite polarity is supplied for each field or frame, so this signal of opposite polarity jumps into each liquid crystal cell through the coupling capacitance CS mentioned above. In particular, shading occurs in which the entire image becomes darker on one side of both surfaces where the time required for the signal to change is long. Similar to the above-mentioned black color image, this shading problem becomes more noticeable when the pixel area is reduced.

Further, crosstalk and shading are also caused by leakage from the switching elements M11 to Mnm.

Therefore, the inventor of the present application previously proposed the following method for preventing such losstalk and shading.

In the apparatus of FIG. 1, a signal as shown in FIG. 5 is supplied to input terminal +11. That is, for example, in an odd field, a signal that is inverted every horizontal period as shown in FIG. 5A is supplied, and in an even field', a signal shown in FIG.
As shown in FIG. 2, a signal is supplied which is inverted every horizontal period and has an opposite phase to the odd field.

As a result, the signal that entered the non-selected pixel in the previous horizontal period is canceled by the signal that has the opposite polarity that enters the next horizontal period. For example, when figure A as shown in Fig. 4 is displayed, the amount of crosstalk during this l field period is given by
0sec), the time of one horizontal period is TH, ΣTHvs (-1)" Cs -1 Tv CM +C8 However, VS is the potential of the background video signal and VB is the potential of the figure, VS -V+, +VB n is the number of horizontal scanning lines in the graphic part, and if n is an even number and VS is constant, the above-mentioned crosstalk will be 0. Even if n is an odd number, the value will be THvs Cs 'rv CM +CS, In the conventional example, it becomes 1 compared to the case of nTlHVs Cs .

Furthermore, since each field has an opposite phase, each pixel is driven by alternating current driving.

In the same way, shading and the effects of leakage from switching elements are also removed.

Crosstalk and shading can thus be prevented in this device.

However, in this case, if we pay attention to the two liquid crystal cells arranged in the vertical direction, we can see that each pixel electrode (26a).

(26b) because mutually opposite phase potentials are accumulated, 2
The electric field formed by the two electrodes has equipotential lines as shown in FIG. For this reason, the liquid crystal between pixels in the vertical direction is no longer modulated due to potential cancellation between the upper and lower pixels, resulting in a smaller display area and lower image quality.

OBJECTS OF THE INVENTION In view of these points, the present invention prevents crosstalk and shading, and removes non-modulated portions between pixels in the vertical direction.

Summary of the Invention The present invention provides a method in which display liquid crystal cells are provided in a matrix,
A plurality of signal lines are provided in parallel between each column of the liquid crystal cells, and every other signal line is connected to serve as a first and second connection point, and wires of opposite polarity are connected to these connection points. While the display signal is supplied, the liquid crystal cells are connected to one side or the other side of the signal lines on both sides for each row via selection elements. 2. A liquid crystal display device, which is connected to the display device, and inverts the display signal supplied to the connection point each time each row is selected, which prevents cross-talk and shading, and The unchanging portion 1ia between pixels in the vertical direction can be removed.

Embodiment In FIG. 7, a signal from an input terminal (1) is supplied to a signal inversion circuit (5) and inverted, and this inverted signal is applied to one fixed contact of a switch [6] and a switch (7).
) is supplied to the other fixed contact of the input terminal fl
) is supplied to the other fixed contact of the switch (6) and one fixed contact of the switch (7). This switch (6), f7), for example, outputs the clock signal φ
It is switched every horizontal period in relation to 2v.

The signals from the switches +6) and (7) are transmitted to every other switching element M1. M3...and M2
゜M4..., every other vertical signal line L
1. L3...and L2. L4... is supplied.

Furthermore, switch notching elements (M l'l , M 12 . . . ), (M 31
．． M32...)... and (M21. M2R...
), (M41°M42...)... are the left vertical signal lines LL, L2... and the right vertical signal line L2. Connected to L3...

Therefore, in this device, the line Ll in the horizontal period of -
, L3 . . . and the lines L2 . L
4. A negative signal is supplied to . Both of the signals supplied to the liquid crystal cell C21 become positive in-phase signals.

As a result, the liquid crystal J)-□ between the above-mentioned vertical pixels
91% okay. Oh, oh. 1 and each vertical signal line L1. Since signals inverted every -horizontal period are supplied to L2..., crosstalk and shading will not occur.

Further, the signal supplied to the input terminal (1) is inverted every vertical period to perform AC driving in each liquid crystal cell.

Note that in the above-mentioned device, the signal of the liquid crystal cell is inverted between pixels in the horizontal direction, and a sinus modulation part is generated between the pixels in the horizontal direction, but this part was originally connected to the vertical signal lines Ls, L2, etc.
・It is impossible to display due to the effects of This is the part that is not transparent.

In addition, in the above-mentioned apparatus, odd numbered horizontal scanning lines and m! The signal is shifted by one pixel ζ from the horizontal scanning line numbered. Therefore, as shown in FIG. 8, the horizontal drive pulse φH1+ψ1(2...
・The timing of the occurrence of is advanced by one clock. Alternatively, as shown in FIG. 9, a delay circuit (8) for one pixel period may be provided, and a switch (9) may be used to delay the signal by one pixel period for each horizontal period.

Note that this device can be applied to a liquid crystal display device using an active matrix using TPT such as amorphous silicon, polysilicon, and silicon on sapphire.

Effects of the Invention According to the present invention, it was possible to prevent crosstalk and shading, and to remove the non-variable i)8 portion between pixels in the vertical direction.

[Brief explanation of the drawings] Figures 1-6 are diagrams for explaining the liquid crystal display device;
FIG. 7 is a configuration diagram of an example of the present invention, and FIGS. 8 and 9 are diagrams for explaining the same. (1) is an input terminal, (2) is a shift register, (5) is a signal inversion circuit, M is a switching element, C is a liquid crystal cell,
(L) is a vertical signal line. Figure 3' Figure 4-4-x-axis Figure 5 Figure 6

Claims (1)

[Claims] Display liquid crystal cells are provided in a matrix, and a plurality of signal lines are provided in parallel between each column of the liquid crystal cells, and every other signal line is connected to the first and second connection points. Display signals of opposite polarity are supplied to these connection points, and the liquid crystal cells are alternately connected to one side or the other side of the signal lines on both sides for each row via selection elements, respectively. A liquid crystal display device, wherein the display signal supplied to the connection point is inverted each time each row is selected.