JP2737200B2 - Liquid crystal display device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device that displays images by arranging liquid crystal display elements in an XY matrix, for example.

[Summary of the Invention]

The present invention relates to a liquid crystal display device, by dividing a second signal line for selecting a horizontal pixel column into a plurality of parts in the horizontal direction, and independently providing a vertical scanning unit for each division.
It is intended to reduce deterioration of a signal generated on a signal line and display a good image.

[Conventional technology]

For example, it has been proposed to display a television image using a liquid crystal (see Japanese Patent Application Laid-Open No. 59-220793).

That is, in FIG. 3, (1) is an input terminal to which a video signal of the television is supplied, and a signal from this input terminal (1) is a switching element M ₁ , M _2. Are supplied to the lines L ₁ , L ₂ ... Lm in the vertical (Y-axis) direction. Note that m is horizontal (X
This is a number corresponding to the number of pixels in the (axis) direction. Further, an m-stage shift register (2) is provided, and clock signals Φ _1H and Φ _2H of m times the horizontal frequency are supplied to the shift register (2). signal [phi _IH, drive pulses are sequentially scanned by the [phi _2H signals φ _H1, φ _H2 ··· φ _Hm switching element M ₁
To Mm. Note that a low potential (V _SS ) and a high potential (V _DD ) are supplied to the shift register (2).
Driving pulses of these two potentials are formed.

Also, for example, each of the lines L _{1 to} Lm has an N-channel FE, for example.
Switching elements M ₁₁ consisting of _{T, M 21 ··· M n1,} M 12, M
₂₂ ... M _n2 ,... M _1m , M _2m . Note that n is a number corresponding to the number of horizontal scanning lines. The other end the liquid crystal cells each C of the switching element M ₁₁ ~Mnm
₁₁ , C ₂₁ ... Cnm are connected to the target terminal (3).

Further, an n-stage shift register (4) is provided, and horizontal shift clock signals Φ _1V and Φ _2V are supplied to the shift register (4). A clock signal Φ _1V from each output terminal of the shift register (4) is provided. , [phi driving pulse signal phi _V1 sequentially scanned by _2V, φ _V2 ··· φ _Vn is horizontal gate lines G ₁ of (X-axis) direction, G ₂ switching elements through ··· Gn M ₁₁ ~Mnm of X each column in the axial direction _{(M 11} ~M _1m),
(M ₂₁ ~M _2m) are supplied to the control terminal of each ··· (M _n1 ~Mnm). Note that _VSS and _VDD are also supplied to the shift register (4) in the same manner as the shift register (2).

That is, in this circuit, the shift register (2),
(4) includes a clock signal Φ _1H , as shown in FIGS.
Φ _2H , Φ _1V , Φ _2V are supplied. And from the shift register (2) phi for each pixel period, as shown in FIG C _H1
~ Φ _Hm is output from the shift register (4).
As shown in FIG. 7, φ _V1 to φ _Vn are output every one horizontal period. Further, the input terminal (1) is supplied with a signal as shown in FIG.

The phi _V1, when phi _H1 is outputted, the switching element M ₁ and M ₁₁ ~M _{1 m} is turned on, the input terminal (1) → M ₁
Potential difference is supplied _{→ L 1 → M 11 → C} 11 → the target terminal (3) the signal current path is supplied is formed in the input terminal to the liquid crystal cell C ₁₁ (1) of the target terminal (3) . Therefore, a charge corresponding to the potential difference due to the signal of the first pixel is sampled and _{held in} the capacity of the cell C11. The light transmittance of the liquid crystal is changed according to this charge amount. It similar to this is successively performed for the cell C ₁₂ ~Cnm, the following additional fields each cell at the time the signal is supplied C ₁₁
The charge amount of ~ Cnm is rewritten.

In this manner, the light transmittance of the liquid crystal cell C ₁₁ ~Cnm is changed corresponding to each pixel of the video signal, which displays the television image is repeated sequentially.

Further, in the case of performing display using liquid crystal, an AC drive is generally used in order to extend the reliability and the life. For example, in the display of a television image, a signal obtained by inverting a video signal for each field or frame is supplied to the input terminal (1). In a liquid crystal display device, a signal is inverted every horizontal period in order to prevent shooting in a vertical direction of display.
That is, the input terminal (1) is supplied with a signal which is inverted every horizontal period and inverted every field or frame as shown in FIG. 4E.

[Problems to be solved by the invention]

However in the apparatus described above, the wiring for the gate lines G ₁ ~Gn has a distribution constant by the gate capacitance and the wiring capacitance of the selected element M ₁₁ ~Mnm connected. For this reason, the drive pulses φ _{V1 to} φ _Vn supplied to the gate lines G _{1 to} Gn become regular rectangular waves at the shift register (4) end, as shown in FIG. in the end will be the waveform as shown in Figure B is obtuse, selection element M ₁₁ ~Mnm
A delay time τ is generated until the ON level of is reached.

This delay time τ is shorter than a certain one horizontal period in a conventional NTSC video signal, for example, about 63 μsec.
Since the horizontal period is halved to about 30 μsec., The delay time τ
Is longer. Therefore, at the opposite end, the driving pulse does not rise sufficiently, and the rewriting of the charge amount of the liquid crystal cell becomes insufficient, so that there is a possibility that right and left pseudo-images may occur in the displayed image.

That is, in the conventional device, there is a problem that the image quality is extremely deteriorated, such as right and left pseudo-tones occurring due to the delay of the signal on the gate line.

The present application has been made in view of such points.

[Means for solving the problem]

The present invention relates to a plurality of first signal lines L ₁ , L ₂ ... Lm arranged in parallel in the vertical direction, and horizontal scanning means (shift register (2)) for driving the first signal lines. And a plurality of second signal lines G ₁ , G _2, ... Gn arranged in parallel in the horizontal direction.
A plurality of vertical scanning means (shift registers (4a) and (4b)) for dividing the second signal line into a plurality of parts in the horizontal direction and driving the second signal line for each division; And selection elements M ₁₁ , M ₁₂ ,.
A liquid crystal display device having liquid crystal cells C ₁₁ , C _12, ... C nm via M nm, wherein the plurality of vertical scanning means supply in-phase pulses to the divided second signal lines; A liquid crystal display device characterized in that:

[Action]

According to this, by dividing the signal line and providing the scanning means for each division, the load on each scanning means is reduced, the rise of the signal of each part on the signal line is accelerated, and the deterioration of the image quality of the displayed image is prevented. can do.

〔Example〕

FIG. 1 shows the configuration of a single liquid crystal display device similar to the conventional example. In this figure, the above-mentioned gate line in the horizontal (X-axis) direction is divided into left and right sides,
G _a1 , G _a2 ‥‥ G _an and G _b1 , G _b2 ‥‥ G _bn . Then, n-stage shift registers (4a) and (4b) are provided independently for these divided gate lines G _{a1 to} G _an and G _{b1 to} G _bn .

Further, clock signals φ _1V and φ _{2V of} horizontal frequency are supplied to these shift registers (4a) and (4b), respectively.
Accordingly, drive pulses φ _V1 , φ _V2 ‥‥ φ _Vn which are exactly the same are extracted from the shift registers (4a), (4b), and these drive pulses are supplied to the gate lines G _{a1 to} G _an , G _{b1 to} G _bn , respectively. Is done.

The gate lines G _{a1 to} G _an are switching elements, respectively.
M _{11 to} M _1P and M _{21 to} M _2P are connected to the control terminals of M _{n1 to} M _nP , and the gate lines G _{b1 to} G _bn are respectively connected to the switching elements M
_{1P + 1} ~M _1m, is connected to a control terminal of the _{M 2P + 1 ~M 2m ‥‥ M} nP + 1 ~Mnm.

In contrast shift register (2) is provided in common to the switching element M ₁ ~Mm, also other configurations are the same as the devices of the prior art.

Therefore, in this device, the gate lines G _a1 and G _b1 , G _a2 and G
Drive pulses φ _V1 , φ _V2 ‥‥ φ _Vn are supplied to _b2 ‥‥ G _an and G _bn , respectively, so that the switching elements M _{11 to} M _1m , M _{21 to} M _2m ‥‥ M _{n1 to} M nm Control is performed in the same manner as in the related art, and an image is displayed as in the related art.

In this case, by dividing the gate line into two in the above-described device, for example, the length of the gate line is halved, and the load or the distribution constant is also halved. Therefore, the driving pulse of the rectangular wave as shown in FIG. 2A at the end on the shift register (4a) (4b) side is the same at the end on the opposite side (located at the center of the screen) of each gate line. Only as shown in FIG. B, it is possible to cause the signal to rise sufficiently fast.

For this reason, it is possible to sufficiently rewrite the charge amounts of all the liquid crystal cells, and it is possible to prevent deterioration of the image quality due to shading on the left and right sides of the displayed image.

Thus, according to this apparatus, by dividing the signal line and providing the scanning means for each division, the load on each scanning means is reduced, the rise of the signal of each part on the signal line is accelerated, and the image quality of the displayed image is degraded. Can be prevented.

Note that, in the above-described apparatus, the gate line may be divided into three or more, and a shift register may be provided for each.

This device is applied to a single liquid crystal display device having one input terminal (1) and one horizontal shift register (2).

〔The invention's effect〕

According to the present invention, by dividing the signal line and providing the scanning means for each division, the load on each scanning means is reduced, the rise of the signal of each part on the signal line is accelerated, and the image quality of the displayed image is degraded. Can now be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram of an example of the present invention, FIG. 2 is a diagram for explaining the same, and FIGS. 3 to 5 are diagrams for explaining a conventional device. L _{1 to} Lm are vertical signal lines, G _{a1 to} G _an , G _{b1 to} G _bn are gate lines,
M ₁₁ ~Mnm switching element, C ₁₁ ~Cnm liquid crystal cell,
(1) is an input terminal, and (2), (4a) and (4b) are shift registers.

Claims (1)

(57) [Claims] 1. A plurality of first signal lines arranged in parallel in a vertical direction, horizontal scanning means for driving the first signal line, and a plurality of second signal lines arranged in parallel in a horizontal direction. And a plurality of vertical scanning means for dividing the second signal line into a plurality of parts in the horizontal direction and driving the second signal line for each division, and a plurality of signal lines for the first and second signal lines. A liquid crystal display device having a liquid crystal cell at each intersection via a selection element, wherein the plurality of vertical scanning units supply in-phase pulses to the divided second signal lines. Liquid crystal display device.